,illustration3 ,,hipparchus ,,in ,,the ,,observatory ,,of ,,alexandria4 ,,the ,,story ,,of ,,the ,,sun1 ,,moon1 ,,and ,,stars ,,by ,,agnes ,,giberne ,,author ,,of 8,,the ,,starry ,,skies10 8,,the ,,world',s ,,foundations10 8,,radiant ,,suns10 ,,etc4 ,illustration ,,with ,,copious ,,additions ,fully ,illustrated ,,cincinnati ,,national ,,book ,,company ,,copyright1 #ahih1 ,,by ,j4 ,t4 ,,jones4 ,,introduction4 ,,by ,,charles ,,pritchard1 ,m4 ,a41 ,f4 ,r4 ,s41 ,,professor ,,of ,,astronomy ,,in ,,the ,,university ,,of ,,oxford4 ,the pages of this volume on a great subject were submitted to my criticism while passing through the press1 with a request from a friend that ,i would make any suggestions which might occur to me for its improvement4 ,naturally1 such a request was entertained1 in the first instance1 with hesitation and misgiving4 ,but after a rapid perusal of the first sheet1 ,i found my interest awakened1 and then gradually secured2 for the book seemed to me to possess certain features of no ordinary character1 and1 in my judgment1 held out the promise of supplying an undoubted want1 thus enabling me to answer a question which ,i have been often asked1 and which had as often puzzled me1 to the effect1 8,can you tell me of any book on astronomy suited to beginners80 ,i think just such a book is here presented to the reader2 for the tale of the stellar universe is therein told with great simplicity1 and perhaps with sufficient completeness1 in an earnest and pleasant style1 equally free1 ,i think1 from inaccuracy or unpardonable exaggeration4 ,we have here the outlines of elementary astronomy1 not merely detailed without mathematics1 but to a very great extent expressed in untechnical language4 ,success in such an attempt ,i regard as a considerable feat1 and one of much practical utility4 ,for the science of astronomy is essentially a science of great magnitude and great difficulty4 ,from the time of ,hipparchus1 some century and a half before the ,christian era1 down to the present day1 the cultivation of astronomy has severely taxed the minds of a succession of men endowed with the rarest genius4 ,the facts and the truths of the science thus secured have been of very slow accretion2 but like all other truths1 when once secured and thoroughly understood1 they are found to admit of very simple verbal expression1 and to lie well within the general comprehension1 and1 ,i may safely add1 within the sympathies of all educated men and women4 ,thus the great astronomers1 the original discoverers of the last twenty centuries1 have labored1 each in his separate field of the vast universe of nature1 and other men1 endowed with other gifts1 have entered on their labors1 and by systematizing1 correlating1 and simplifying the expression of their results1 have brought the whole within the grasp of cultivated men engaged in other branches of the varied pursuits of our complicated life4 ,it is in this sort of order that the amelioration and civilization of mankind have proceeded1 and at the present moment are1 ,i hope and believe1 rapidly proceeding4 ,it was1 ,i suspect1 under this point of view1 though half unconsciously so1 that my attention was arrested by the book now presented to the reader2 for we have here many of the chief results of the laborious researches of such men as ,ptolemy1 ,kepler1 ,newton1 ,herschel1 ,fraunhofer1 ,janssen1 ,lockyer1 ,schiaparelli1 and others--no matter where accumulated or by whom recorded--filtered through the mind of a thoughtful and cultured lady1 and here presented to other minds in the very forms wherein they have been assimilated and pictured in her own4 ,and these forms and pictures are true4 ,it is in this way that the intellectual 8protoplasm0 of the human mind is fostered and practically disseminated4 ,and1 then1 there is still another point of view from which this general dissemination of great truths in a simple style assumes an aspect of practical importance4 ,i allude to the influences of this process on the imaginative or poetic side of our complex nature4 ,wordsworth1 in one of his prefaces1 has stated so clearly the truth on this subject that ,i can not do better than give his words4 8,if the time should ever come10 he says1 8when what is now science becomes familiarized to men1 then the remotest discoveries of the chemist1 the botanist1 the mineralogist1 will be as proper objects of the poet's art as any upon which it can be employed4 ,he will be ready to follow the steps of the man of science2 he will be at his side1 carrying sensation into the midst of the objects of science itself4 ,the poet will lend his divine spirit to aid the transfiguration1 and will welcome the being thus produced as a dear and genuine inmate of the household of man40 ,it is for reasons such as here stated that ,i heartily commend this book to the attention of those who take an interest in the advancement of the intellectual progress and culture of society4 ,the story of the ,kosmos is told by the authoress in her own language and after her own method4 ,i believe1 as ,i have said1 the story is correct4 ,,oxford ,,university4 ,,contents4 ,,chapter4 ,,page4 ,i4 ,,the ,,earth ,,one ,,of ,a ,,family1 #ac ,,ii4 ,,the ,,head ,,of ,,our ,,family1 #bd ,,iii4 ,,what ,,binds ,,the ,,family ,,together1 #cd ,,iv4 ,,the ,,leading ,,members ,,of ,,our ,,family4--,,first ,,group1 #df ,v4 ,,the ,,leading ,,members ,,of ,,our ,,family4--,,second ,,group1 #ee ,,vi4 ,,the ,,moon1 #fb ,,vii4 ,,visitors1 #gc ,,viii4 ,,little ,,servants1 #hc ,,ix4 ,,neighboring ,,families1 #ie ,x4 ,,our ,,neighbors' ,,movements1 #ajf ,,xi4 ,,more ,,about ,,the ,,solar ,,system1 #abb ,,xii4 ,,more ,,about ,,the ,,sun1 #acc ,,xiii4 ,,yet ,,more ,,about ,,the ,,sun1 #adh ,,xiv4 ,,more ,,about ,,the ,,moon1 #aeg ,,xv4 ,,yet ,,more ,,about ,,the ,,moon1 #afd ,,xvi4 ,,mercury1 ,,venus1 ,,and ,,mars1 #ahj ,,xvii4 ,,jupiter1 #aii ,,xviii4 ,,saturn1 #bad ,,xix4 ,,uranus ,,and ,,neptune1 #bbe ,,xx4 ,,comets ,,and ,,meteorites1 #bdj ,,xxi4 ,,more ,,about ,,comets ,,and ,,meteorites1 #bdf ,,xxii4 ,,many ,,suns1 #bfg ,,xxiii4 ,,some ,,particular ,,suns1 #bgh ,,xxiv4 ,,different ,,kinds ,,of ,,suns1 #bia ,,xxv4 ,,groups ,,and ,,clusters ,,of ,,suns1 #cjd ,,xxvi4 ,,the ,,problem ,,of ,,sun ,,and ,,star ,,distances1 #caj ,,xxvii4 ,,measurement ,,of ,,star ,,distances1 #cbj ,,xxviii4 ,,the ,,milky ,,way1 #cbi ,,xxix4 ,a ,,whirling ,,universe1 #ccg ,,xxx4 ,,reading ,,the ,,light1 #cdd ,,xxxi4 ,,stellar ,,photography1 #cee ,,xxxii4 ,,the ,,dawn ,,of ,,astronomy1 #cfc ,,xxxiii4 ,,modern ,,astronomy1 #cge ,,xxxiv4 ,,sir ,,isaac ,,newton1 #chb ,,xxxv4 ,,later ,,astronomy1 #cic ,,list ,,of ,,illustrations4 ,,page4 ,hipparchus in the ,observatory at ,alexandria ,frontispiece4 ,the ,solar ,system #ae ,the ,pleiades #ai ,sun-spots #bi ,phases of ,mercury before ,inferior ,conjunction--,evening ,star #ej ,appearance of the ,full ,moon #fc ,one ,form of ,lunar ,crater #fi ,the ,earth as ,seen from the ,moon #ga ,passage of the ,earth and the ,moon through the ,tail of a ,comet #gf ,passage of the ,comet of #ahdc ,close to the ,sun #gi ,meteor ,emerging from ,behind a ,cloud #hd ,the ,great ,shower of ,shooting-stars1 ,november #bg1 #ahgb #ij ,constellation of the ,great ,bear #ajh ,the ,great ,bear #ej1jjj ,years ,ago #aji ,the ,great ,bear #ej1jjj ,years ,hence #aji ,constellation of ,orion as it ,appears ,now #aaj ,constellation of ,orion #ej1jjj ,years ,hence #aaa ,position of ,planets ,inferior to ,jupiter--,showing the ,zone of the ,asteroids #abc ,comparative ,size of the ,planetary ,worlds #acj ,a ,typical ,sun-spot #ace ,a ,solar ,eruption #ach ,sun-flames1 ,may #c1 #ahib #adc ,solar ,corona and ,prominence #aeb ,comparative ,size of the ,earth and ,sun #aee ,the ,moon--an ,expired ,planet #aei ,the ,lunar ,crater ,copernicus #agj ,lunar ,eruption--,brisk ,action #agb ,lunar ,eruption--,feeble ,action #agc ,nicolaus ,copernicus #agf ,phases of ,venus #ahf ,mars and the ,path of its ,satellites #aia ,general ,aspect of ,jupiter--,satellite and its ,shadow #bjj ,satellites of ,jupiter ,compared with the ,earth and ,moon #bjf ,the ,system of ,jupiter #bjh ,orbits of ,nine ,comets ,captured by ,jupiter #bac ,saturn and the ,earth--,comparative ,size #bae ,ideal ,view of ,saturn's ,rings and ,satellites from the ,planet #bbb ,great ,astronomers of ,earlier ,times #bbg ,the ,great ,comet of #ahaa #bdg ,donati's ,comet1 #aheh #bdi ,great ,comet of #agdd #bed ,the ,first ,comet of #ahhh--;,june #d #bee ,great ,comet of #afhj #bfj ,great ,comet of #agfi #bfa ,baron ,alexander ,von ,humboldt #bfd ,a ,telescopic ,field in the ,milky ,way #bgj ,cygnus1 ,constellation of #bgi ,stars whose ,distances are ,best ,known #bha ,lyra1 ,constellation of #big ,constellations in the ,northern ,hemisphere #cjj ,a ,cluster of ,stars in ,centaurus #cje ,the ,great ,nebula in ,andromeda1 ,compared with ,size of the ,solar ,system #cjg ,a ,cluster of ,stars in ,perseus #ccb ,hercules1 ,constellation of #cch ,the ,great ,bear1 ,constellation of #cda ,the ,prism and ,spectrum #cdd ,the ,spectroscope #cde ,spectra1 ,showing the ,dark ,lines #cdg ,great ,astronomers of ,later ,times #cgg ,sir ,isaac ,newton #chf ,eye-piece of ,lick ,telescope #djg ,lick ,observatory #dji ,professor ,e4 ,e4 ,barnard #daj ,,the ,,story ,,of ,,the ,,sun1 ,,moon1 ,,and ,,stars4 ,,chapter ,i4 ,,the ,,earth ,,one ,,of ,a ,,family4 ,what is this earth of ours8 ,something very great--and yet something very little4 ,something very great1 compared with the things upon the earth2 something very little1 compared with the things outside the earth4 ,and as our journeyings together are for a while to be away from earth1 we shall find ourselves obliged to count her as something quite small in the great universe1 where so many larger and mightier things are to be found1--if indeed they are mightier4 ,not that we have to say good-bye altogether to our old home4 ,we must linger about her for a while before starting1 and afterwards it will be often needful to come back1 with speed swifter than the flight of light1 that we may compare notes on the sizes and conditions of other places visited by us4 ,but first of all3 what is this earth of ours8 ,it was rather a pleasant notion which men held in olden days1 that we--that great and important 8,we0 which loves to perch itself upon a height--stood firm and fixed at the very center of everything4 ,the earth was supposed to be a vast flat plain1 reaching nobody could tell how far4 ,the sun rose and set for us alone2 and the thousands of stars twinkled in the sky at night for nobody's good except ours2 and the blue sky overhead was a crystal covering for the men of our earth1 and nothing more4 ,in fact1 people seem to have counted themselves not merely to have had a kind of kingship over the lower animals of our earth1 but to have been kings over the whole universe4 ,sun1 stars1 and sky1 as well as earth1 were made for man1 and for man only4 ,this was the common belief1 though even in those olden days there were some who knew better4 ,but the world in general knows better now4 ,earth the center of the universe6 ,why1 she is not that of even the particular family in the heavens to which she belongs4 ,for we do not stand alone4 ,the earth is one of a family of worlds1 and that family is called ,,the ,,solar ,,system4 ,and so far is our earth from being the head of the family1 that she is not even one of the more important members4 ,she is merely one of the little sisters1 as it were4 ,men not only believed the earth1 in past days1 to be at the center of the universe2 but also they believed her to remain there without change4 ,sun1 moon1 stars1 planets1 sky1 might move2 but never the earth4 ,the solid ground beneath their feet1 that at least was firm4 ,every day the sun rose and set1 and every night the stars1 in like manner1 rose and set4 ,but this was easily explained4 ,we on our great earth stood firm and still1 while sun1 moon1 stars1 went circling round us once in every twenty-four hours1 just for our sole and particular convenience4 ,what an important personage man must have felt himself then in ,god's great universe6 ,once again1 we know better now6 ,illustration3 ,,the ,,solar ,,system4 ,for it is the earth that moves1 and not the sun2 it is the earth that moves1 and not the stars4 ,the daily movements of sun and stars1 rising in the east1 traveling over the sky1 and setting in the west1 are no more real movements on their part than1 when we travel in a rail way-train1 the seeming rush of hedges1 telegraph posts1 houses1 and fields is real4 ,they are fixed and we are moving2 yet the movement appears to us to be not ours but theirs4 ,still more strongly would this appear to be the case if there were no noise1 no shaking1 no jarring and trembling1 to make us feel that we are not at rest4 ,sometimes when a train begins to move gently out of a station1 from among other trains1 it is at the first moment quite impossible to say whether the movement belongs to the train in which we are seated or to a neighboring train4 ,and in the motions of our earth there is no noise1 no shaking1 no jarring--all are rapid1 silent1 and even4 ,if you were rising through the air in a balloon1 you would at first only know your own movement by seeing the earth seem to drop away from beneath you4 ,and just so we can only know the earth's movements by seeing how worlds around us seem to move in consequence4 ,when ,i speak of the ,universe1 ,i mean the whole of ,god's mighty creation as far as the stars reach4 ,sometimes the word is used in this sense1 and sometimes it is used only for a particular part of creation nearer to us than other parts4 ,at present1 however1 we will put aside all thought of the second narrower meaning4 ,the wisest astronomer living can not tell us how far the stars reach4 ,we know now that there is no firm crystal covering over our heads1 dotted with bright points here and there2 but only the wide open sky or heaven1 containing millions of stars1 some nearer1 some farther1 some bright enough to be seen by us all1 some only visible through a telescope4 ,people talk often of the stars being 8set in space20 and the meaning of 8space0 is simply 8room40 ,where you are must be space1 or you could not be there4 ,but it is when we get away from earth1 and travel in thought through the wide fields of space1 where ,god has placed his stars1 that we begin to feel how vast it is1 and what specks we are ourselves--nay1 what a speck our very earth is1 in this great and boundless creation4 ,for there is no getting to the borders of space4 ,as one telescope after another is made1 each one stronger in power and able to reach farther than the last1 still more and more stars are seen1 and yet more and more behind and beyond1 in countless millions4 ,it is the same all round the earth4 ,the old notion about our world being a flat plain has been long since given up4 ,we know her now to be a round globe1 not fixed1 but floating like the stars in space4 ,when you look up into the sky1 you are looking exactly in the opposite direction from where you would be looking up if you were in ,australia4 ,for ,australia's 8up0 is our 8down10 and our 8down0 is ,australia's 8up40 ,or1 to put it more truly1 8up0 is always in the direction straight away from this earth1 on whatever part of it you may be standing2 and 8down0 is always towards the center of the earth4 ,all round the globe1 in north1 south1 east1 west1 whether you are in ,europe1 ,asia1 ,africa1 or ,america1 though you will see different stars in certain different quarters of the earth1 still overhead you will find shining countless points of light4 ,and now1 what are these stars8 ,this is a matter on which people are often confused1 and on which it is well to be quite clear before going one step farther4 ,some of the stars you have most likely often noticed4 ,the seven chief stars of the ,great ,bear are known to a large number of people2 and there are few who have not admired the splendid constellation of ,orion4 ,perhaps you also know the ,w-shape of ,cassiopeia1 and the brilliant shining of ,sirius1 and the soft glimmer of the ,pleiades4 ,the different constellations or groups of principal stars have been watched by men for long ages past4 ,they are called the fixed stars1 for they do not change4 ,how many thousands of years ago they were first arranged by men into these groups1 and who first gave them their names1 we can not tell4 ,true1 night by night1 through century after century1 they rise1 and cross the sky1 and set4 ,but those are only seeming movements4 ,precisely as the turning round of the earth upon her axis1 once in every twenty-four hours1 makes the sun appear to rise and cross the sky and set1 in the day-time2 so also the same turning of the earth makes the stars appear to do the same in the night-time4 ,there is another seeming movement among the stars1 which is only in seeming4 ,some come into view in summer which can not be seen in winter2 and some come into view in winter which can not be seen in summer4 ,for the sun1 moving on his pathway through the sky1 hides those stars which shine with him in the day-time4 ,the zodiac is an imaginary belt in the heavens1 sixteen or eighteen degrees wide1 containing the twelve constellations through which the sun passes4 ,and as he passes from point to point of his pathway1 he constantly conceals from us fresh groups of stars by day1 and allows fresh groups to appear by night4 ,speaking generally1 however1 the stars remain the same year after year1 century after century4 ,the groups may still be seen as of old1 fixed and unchanging4 ,illustration3 ,,the ,,pleiades4 ,what are these stars8 ,stars and planets have both been spoken about4 ,there is a great difference between the two4 ,perhaps if you were asked whether the sun is most like to a star or a planet1 you would be rather at a loss2 and many who have admired the brilliant evening star1 ,venus1 often to be seen after sunset1 would be surprised to learn that the evening star is in reality no star at all4 ,a star is a sun4 ,our sun is nothing more nor less than a star4 ,each one of the so-called 8fixed stars10 that you see shining at night in the sky1 is a sun like our sun2 only some of the stars are larger suns and some are smaller suns than ours4 ,the main reason why our sun looks so much larger and brighter than the stars is1 that he is so very much nearer to us4 ,the stars are one and all at enormous distances from the earth4 ,by and by we will go more closely into the matter of their distance1 compared with the distance of the sun4 ,at present it is enough to say that if many of the stars were placed just as near to us as our sun is placed1 they would look just as large and bright2 while there are some that would look a great deal larger and brighter4 ,and if our sun were to travel away from us1 to the distance of the very nearest of the little twinkling stars1 he would dwindle down and down in size and brilliancy1 till at last we should not be able to tell him apart from the rest of the stars4 ,i have told you that the stars are called 8fixed0 because they keep their places1 and do not change from age to age4 ,though the movement of the earth makes them seem all to sweep past every night in company1 yet they do not travel in and out among one another1 or backwards and forwards1 or from side to side4 ,at all events1 if there be such changes1 they are so slow and so small as to be exceedingly difficult to find out4 ,each group of stars keeps its own old shape1 as for hundreds of years back4 ,but among these fixed stars there are certain stars which do go to and fro1 and backwards and forwards4 ,now they are to be seen in the middle of one constellation1 and now in the middle of another4 ,these restless stars were long a great perplexity4 ,men named them ,planets or ,wanderers4 ,we know now that the planets are in reality not stars at all1 and also that they are not nearly so far away from us as the fixed stars4 ,in fact1 they are simply members of our own family--the ,solar ,system4 ,they are worlds1 more or less like the world we live in2 and they travel round and round the sun as we do1 each more or less near to him2 and they depend upon him for heat and light1 in more or less the same manner as ourselves4 ,therefore1 just as our sun is a star1 and stars are suns1 so our earth or world is a planet1 and planets are worlds4 ,,earth is the name we give to that particular world or planet on which we live4 ,planets may generally be known from stars by the fact that they do not twinkle4 ,but the great difference between the two lies in the fact that a star shines by its own radiant1 burning light1 whereas a planet shines merely by light reflected or borrowed from the sun4 ,but how were the earth and the other worlds made8 ,let us imagine an immense gaseous mass placed in space4 ,attraction is a force inherent in every atom of matter4 ,the denser portion of this mass will insensibly attract towards it the other parts1 and in the slow fall of the more distant molecules towards this more attractive region1 a general motion is produced1 incompletely directed towards this center1 and soon involving the whole mass in the same motion of rotation4 ,the simplest form of all1 even in virtue of this law of attraction1 is the spherical form4 ,it is that which a drop of water takes1 and a drop of mercury if left to itself4 ,the laws of mechanics show that1 as this gaseous mass condenses and shrinks1 the motion of rotation of the nebula is accelerated4 ,in turning1 it becomes flattened at the poles1 and gradually takes the form of an immense lens-shaped mass of gas4 ,it has begun to turn so quickly as to develop at its exterior circumference a centrifugal force superior to the general attraction of the mass1 as when we whirl a sling4 ,the inevitable consequence of this excess is a rupture of the equilibrium1 which detaches an external ring4 ,this gaseous ring will continue to rotate in the same time and with the same velocity2 but the nebulous mother will be henceforth detached1 and will continue to undergo progressive condensation and acceleration of motion4 ,the same feat will be reproduced as often as the velocity of rotation surpasses that by which the centrifugal force remains inferior to the attraction4 ,it may have happened also that secondary centers of condensation would be formed even in the interior of the nebula4 ,in our system the rings of ,saturn still subsist4 ,the successive formation of the planets1 their situation near the plane of the solar equator1 and their motions of translation round the same center1 are explained by the theory which we are discussing4 ,the most distant known planet1 ,neptune1 would be detached from the nebula at the epoch when this nebula extended as far as the planet1 out to nearly three thousand millions of miles1 and would turn in a slow revolution requiring a period of #afe years for its accomplishment4 ,the original ring could not remain in the state of a ring unless it was perfectly homogeneous and regular2 but such a condition is1 so to say1 unrealizable1 and it did not delay in condensing itself into a sphere4 ,successively1 ,uranus1 ,saturn1 ,jupiter1 the army of small planets1 ,mars1 would thus be detached or formed in the interior of this same nebula4 ,afterwards came the earth1 of which the birth goes back to the epoch when the sun had arrived at the earth's present position4 ,venus and ,mercury would be born later4 ,will the sun give birth to a new world8 ,this is not probable4 ,,chapter ,,ii ,,the ,,head ,,of ,,our ,,family4 ,people began very early in the history of the world to pay close attention to the sun4 ,and no wonder4 ,we owe so much to his heat and light that the marvel would be if men had not thought much about him4 ,was the sun really any larger than he looked1 and if so1 how much larger was he8 ,and what was his distance from the earth8 ,these were two of the questions which puzzled our ancestors the longest4 ,if once they could have settled exactly how far off the sun really was1 they could easily have calculated his exact size2 but this was just what they could not do4 ,so one man supposed that the sun must be quite near1 and very little larger than he looked4 ,another thought he might be seventy-five miles in diameter4 ,a third ventured to believe that he was larger than the country of ,greece4 ,a fourth was so bold as to imagine that he might even outweigh the earth herself4 ,after a while many attempts were made to measure the distance of the sun2 and a great many different answers to this difficult question were given by different men1 most of them very wide of the mark4 ,it is only of late years that the matter has been clearly settled4 ,and1 indeed1 it was found quite lately that a mistake of no less than three millions of miles had been made1 notwithstanding all the care and all the attention given4 ,but though three millions of miles sounds a great deal1 yet it is really very little--only a tiny portion of the whole4 ,for the distance of the sun from the earth is no less than about ,,ninety-,,three ,,millions ,,of ,,miles4 ,ninety-three millions of miles6 ,can you picture that to yourself8 ,try to think what is meant by a thousand miles4 ,our earth is eight thousand miles in diameter4 ,in other words1 if you were to thrust a gigantic knitting-needle through her body1 from the ,north ,pole to the ,south ,pole1 it would have to be about eight thousand miles long4 ,to reach the thought of one million1 you must picture one thousand times one thousand4 ,our earth is about twenty-five thousand miles round4 ,if you were to start from the mouth of the ,river ,amazon1 in ,south ,america1 and journey straight round the whole earth on the equator1 till you came back to the same point1 you would have traveled about twenty-five thousand miles4 ,but that would be a long way off from a million miles4 ,you would have gone only once round the earth4 ,now a cord one million miles in length could be wrapped1 not once only1 but forty times1 round and round the earth4 ,and when you have managed to reach up to the thought of one million miles1 you have then to remember that the sun's distance is ninety-three times as much again4 ,so1 to picture clearly to ourselves the actual meaning of 8ninety-three millions of miles0 is not so easy4 ,suppose it were possible to lay a railroad from here to the sun4 ,if you could journey thither in a perfectly straight line1 at the rate of thirty miles an hour1 never pausing for one single minute1 night or day1 you would reach the sun in about three hundred and forty-six years4 ,thirty miles an hour is a slow train4 ,suppose we double the speed1 and make it an express train1 rushing along at the pace of sixty miles an hour4 ,then you might hope to reach the end of your journey in one hundred and seventy-three years4 ,if you had quitted this earth early in the eighteenth century1 never stopping on your way1 you would be1 just about now1 near the end of the nineteenth1 arriving at the sun4 ,so much for the sun's distance from us4 ,now as to his size4 ,i have already mentioned that our earth's diameter--that is1 her through measure1 as1 for instance1 the line drawn straight from ,england through her center to ,new ,zealand--is about eight thousand miles4 ,this sounds a good deal4 ,but what do you think of the diameter of the sun being no less than eight hundred and fifty-eight thousand miles8 ,the one is eight thousand miles1 the other over eight hundred thousand6 ,suppose you had a long slender pole which would pass through the middle of the earth1 one end just showing at the ,north ,pole and the other at the ,south ,pole4 ,you would need more than a hundred and eight of such poles1 all joined together1 to show the diameter of the sun4 ,the sun seems not to be made of nearly such heavy materials as the earth4 ,he is what astronomers call less 8dense10 less close and compact in his make1 just as wood is less dense and heavy than iron4 ,still1 his size is so enormous1 that if you could have a pair of gigantic scales1 and put the sun into one scale and the earth with every one of her brother and sister planets into the other1 the sun's side would go down like lightning4 ,he would be found to weigh seven hundred and fifty times as much as all the rest put together4 ,and1 it would take more than twelve hundred thousand little earths like ours1 rolled into one huge ball1 to make a globe as large as the sun4 ,in the beginning of the seventeenth century a man named ,fabricius was startled by the sight of a certain black spot upon the face of the sun4 ,he watched till too dazzled to look any longer1 supposing it to be a small cloud1 yet anxious to learn more4 ,next day the spot was there still1 but it seemed to have moved on a little way4 ,morning after morning this movement was found to continue1 and soon a second spot1 and then a third spot1 were observed creeping in like manner across the sun4 ,after a while they vanished1 one at a time1 round his edge1 as it were2 but after some days of patient waiting on the part of the lookers-on1 they appeared again at the opposite edge1 and once more began their journey across4 ,fabricius seems to have been the first1 but he was not the last1 to watch sun-spots4 ,many astronomers have given close attention to them4 ,modern telescopes1 and the modern plan of looking at the sun through darkened glass1 have made this possible in a way that was not possible two or three hundred years ago4 ,the first important discovery made through the spots on the sun1 was that the sun turns round upon his axis1 just in the same manner that the earth turns round upon hers4 ,instead of doing so once in the course of each twenty-four hours1 like the earth1 he turns once in the course of about twenty-five days4 ,it must not be supposed that the spots seen now upon the sun are the same spots that ,fabricius saw so long ago4 ,there is perpetual change going on2 new spots forming1 old spots vanishing2 one spot breaking into two1 two spots joining into one1 and so on4 ,even in a single hour great alterations are sometimes seen to take place4 ,still1 many of the spots do remain long enough and keep their shapes closely enough to be watched from day to day1 and to be known again as old friends when they reappear1 after being about twelve days hidden on the other side of the sun4 ,so that the turning of the sun upon his axis has become1 after long and careful examination1 a certain known fact4 ,for more than thirty years one astronomer kept close watch over the spots on every day that it was possible to see the sun4 ,much has been learned from his resolute perseverance4 ,now what are these spots8 ,one thing seems pretty sure1 and that is that they are caused by some kind of tremendous storms or cyclones taking place on the surface of that huge ball of fire4 ,illustration3 ,,sun ,,spots4 ,the first attentive observer of the sun1 ,scheiner1 at first regarded the spots as satellites--an indefensible opinion1 which1 however1 some have attempted to revive4 ,galileo attributed them to clouds or vapors floating in the solar atmosphere2 this was the best conclusion which could be drawn from the observations of that epoch4 ,this opinion met for a long time with general approval2 it has even been renewed in our day4 ,some astronomers1 and among them ,lalande1 believed1 on the contrary1 that they were mountains1 of which the flanks1 more or less steep1 might produce the aspect of the penumbra--an opinion irreconcilable with the proper motion which the spots sometimes possess in a very marked manner4 ,it is not usual1 in fact1 to see mountains traveling4 ,derham attributed them to the smoke issuing from the volcanic craters of the sun1 an opinion revived and maintained in recent times by ,chacornac4 ,several savants1 regarding the sun as a liquid and incandescent mass1 have also explained the spots by immense cinders floating on this ocean of fire4 ,but a century had scarcely elapsed after the epoch when the spots were observed for the first time1 when an ,english astronomer1 ,wilson1 showed with certainty that the spots are hollow4 ,we do not know with any certainty whether the sun is through and through one mass of glowing molten heat1 or whether he may have a solid and even cool body within the blazing covering4 ,some have thought the one1 and some the other4 ,we only know that he is a mighty furnace of heat and flame1 beyond anything that we can possibly imagine on our quiet little earth4 ,it seems very sure that no such thing as 8quietness0 is to be found on the surface of the sun4 ,the wildest and fiercest turmoil of rushing wind and roaring flame there prevails4 ,the cyclones or hurricanes which take place are sometimes so rapid and so tremendous in extent1 tearing open the blazing envelope of the sun1 and showing glimpses of fiery though darker depths below1 that we1 on our far-distant earth1 can actually watch their progress4 ,astronomers speak of the 8quivering fringe of fire0 all around the edge of the sun1 visible through telescopes4 ,but the sun is perpetually turning on his axis1 so that each hour fresh portions of his surface thus pass the edge1 showing the same appearance4 ,what conclusion can we come to but that the whole enormous surface of the sun is one restless1 billowy sea of fire and flame8 ,it sounds to us both grand and startling to hear of the mighty outbreaks from ,mount ,vesuvius1 or to read of glowing lava from a volcano in ,hawaii pouring in one unbroken stream for miles4 ,but what shall be thought of rosy flames mounting to a height of fifty or a hundred thousand miles above the edge of the sun8 ,what shall be thought of a tongue of fire long enough to fold three or four times round our solid earth8 ,what shall be thought of the awful rush of burning gases1 sometimes seen1 borne along at the rate of one or two or even three hundred miles in a single second across the sun's surface8 ,what shall be thought of the huge dark rents in this raging fiery ocean1 rents commonly from fifty to one hundred thousand miles across1 and not seldom more8 ,fifty thousand miles6 ,a mere speck1 scarcely visible without a telescope2 yet large enough to hold seven earths like ours flung in together4 ,the largest spot measured was so enormous that eighteen earths might have been arranged in a row across the breadth of it1 like huge boulders of rock in a mountain cavern2 and to have filled up the entire hole about one hundred earths would have been needed4 ,it is well to grow familiar with certain names given by astronomers to certain parts of the sun4 ,the round shining disk or flat surface1 seen by all of us1 is called the photosphere1 or 8light-sphere40 ,it has a tolerably well-defined edge or 8limb10 and dazzles the eye with its intense brightness4 ,across the photosphere the spots move1 sometimes many1 sometimes few1 in number4 ,besides the dark spots1 there are spots of extreme brilliancy1 standing out on even that dazzling surface1 which causes a piece of white-hot iron to look black and cold by contrast4 ,these extra-radiant spots which come and go1 and at times change with great rapidity1 are named facul--a ,latin word meaning 8torches40 ,at the edge of the photosphere astronomers see what has been already mentioned1 that which is sometimes called the chromotosphere1 which one has named 8the sierra10 and which another has described as 8a quivering fringe of fire40 ,the waves of the sea1 on a stormy day1 seen in the distance rising and breaking the horizon-line1 may serve as an illustration2 only in the sun the waves are of fire1 not water4 ,what must their height be1 to be thus visible at a distance of ninety-three millions of miles8 ,outside the sierra are seen1 at certain seasons1 bright1 8rose-colored prominences0 or flames of enormous height4 ,during an eclipse1 when the dark body of the moon comes between the sun and us1 exactly covering the photosphere1 these red tips stand out distinctly beyond the edge of sun and moon4 ,their changes have been watched1 and their height repeatedly measured4 ,some are so lofty that ten little earths such as ours might be heaped up1 one upon another1 without reaching to their top4 ,whether they are in character at all like the outbursts from our own volcanoes it is hard to say4 ,to compare the two would be rather like comparing a small kitchen fire with a mighty iron-smelting furnace4 ,the facul1 the sierra1 and the prominences are visible only through a telescope4 ,outside these red flames or 8prominences0 is the corona1 commonly divided into the inner and outer coronas4 ,many different explanations have been offered of this beautiful crown of light round the sun1 plainly visible to the naked eye during an eclipse4 ,but here again we know little1 and must be content to watch and wait4 ,,chapter ,,iii4 ,,what ,,binds ,,the ,,family ,,together8 ,what is it which binds together all the members of the ,solar ,system8 ,ah1 what8 ,why should not the sun at any moment rush away in one direction1 the earth in a second1 the planets in half a dozen others8 ,what is there to hinder such a catastrophe8 ,nothing--except that they are all held together by a certain close family tie2 or1 more correctly1 by the powerful influence of the head of the family4 ,this mysterious power which the sun has1 and which all the planets have also in their smaller degrees1 is called ,attraction4 ,sometimes it is named ,gravitation or ,gravity4 ,when we speak1 as we often do1 of the law of attraction or gravitation1 we mean simply this--that throughout the universe1 in things little and great1 is found a certain wonderful something1 in constant action1 which we call a 8law40 ,what the 8something0 may be1 man can not tell2 for he knows it only by its effects4 ,but these effects are seen everywhere1 on all sides1 in the earth and in the universe4 ,it is well named in being called a 8law20 for we are compelled to obey it4 ,none but the ,divine ,lawgiver who made this law can for a single moment suspend its working4 ,what causes an apple to fall to the ground when it drops from the branch8 ,why should it not1 instead1 rise upwards8 ,because1 of course1 it is heavy1 or has weight4 ,but what is weight8 ,simply this--that the earth draws or drags everything downwards towards herself by the power of attraction4 ,every substance1 great or small1 light or heavy1 is made up of tiny atoms4 ,each one of these atoms attracts or draws all the other atoms towards itself2 and the closer they are together1 the more strongly they pull one another4 ,the atoms in a piece of iron are much closer than the atoms in a piece of wood2 therefore the iron is called the 8more dense0 of the two1 and its weight or 8mass0 is greater4 ,the more closely the atoms are pressed together1 the greater the number of them in a small space1 and the more strong the drawing towards the earth2 for the earth draws each one of these atoms equally4 ,that is only another way of saying that a thing is 8heavier40 ,if you drop a stone from the top of a cliff1 will it rise upwards or float in the air8 ,no1 indeed4 ,the pull of the earth's attraction1 dragging and still dragging downward1 makes it rush through the air1 with speed quickening each instant1 till it strikes the ground4 ,every single atom in every single body pulls every other atom1 whether far or near4 ,the nearer it is1 the stronger always the pulling4 ,we do not always feel this1 because the very much greater attraction of the earth hides--or smothers1 as we may say--the lesser attraction of each small thing for another4 ,but though you and ,i might stand side by side upon earth1 and feel no mutual attraction1 yet if we could mount up a few thousands of miles1 far away from earth1 and float in distant space1 there we should find ourselves drawn together1 and unable to remain apart4 ,now precisely as an apple falling from a tree and a stone dropping from a cliff are dragged downward to the earth1 just so our earth and all the planets are dragged downwards towards the sun and towards each other4 ,the law of the earth's attraction of all objects on its surface to itself was indistinctly suspected a very long time ago2 but it was the great ,newton who first discovered that this same law was to be found working among the members of the whole ,solar ,system4 ,the sun attracts the earth1 and the earth attracts the sun4 ,but the enormous size of the sun compared with our earth--like a great nine-foot globe beside a tiny one-inch ball--makes our power of attraction to be quite lost sight of in his1 which is so much greater4 ,the principle of gravitation is of far wider scope than we have yet indicated4 ,we have spoken merely of the attraction of the earth1 and we have stated that its attraction extends throughout space4 ,but the law of gravitation is not so limited4 ,not only does the earth attract every other body1 and every other body attract the earth1 but each of these bodies attracts each other2 so that1 in its more complete shape1 the law of gravitation announces that 8every body in the universe attracts every other body with a force which varies inversely as the square of the distance40 ,it is impossible for us to overestimate the importance of this law4 ,it supplies the clue by which we can unravel the complicated movements of the planets4 ,it has led to marvelous discoveries1 in which the law of gravitation has enabled us to anticipate the telescope1 and1 indeed1 actually to feel the existence of bodies before those bodies have even been seen4 ,we come now to another question4 ,if the sun is pulling with such power at the earth and all her sister planets1 why do they not fall down upon him8 ,what is to prevent their rolling some day into one of those deep rents in his fiery envelope8 ,did you ever tie a ball to a string1 and swing it rapidly round and round your head8 ,if you did1 you must have noticed the steady outward pull of the ball4 ,the heavier the ball1 and the more rapid its whirl1 the stronger the pull will be4 ,let the string slip1 and the rush of the ball through the air to the side of the room will make this yet more plain4 ,did you ever carry a glass of water quickly along1 and then1 on suddenly turning a corner1 find that the water has not turned with you8 ,it has gone on in its former direction1 leaving the glass1 and spilling itself on the floor4 ,the cause in both cases is the same4 ,here is another 8law of nature10 so-called4 ,though we can neither explain nor understand why and how it is so1 we see it to be one of the fixed rules of ,god's working in every-day life throughout his universe4 ,the law1 as we see it1 seems to be this3 ,everything which is at rest must remain at rest1 until set moving by some cause outside of1 or independent of itself2 and everything which is once set moving1 must continue moving in a straight line until checked4 ,according to this a cannon-ball lying on the ground ought to remain there until it is set in motion2 and1 once set in motion by being fired from a cannon1 it ought to go on forever4 ,exactly so--if nothing stops it4 ,but the earth's attraction draws the cannon-ball downward1 and every time it strikes the ground it is partly checked4 ,also each particle of air that touches it helps to bring it to rest4 ,if there were no earth and no air in the question1 the cannon-ball might rush on in space for thousands of years4 ,why did the water get spilled8 ,because it necessarily continued moving in a straight line4 ,your sudden change of direction compelled the solid glass to make the same change1 but the liquid water was free to go straight on in its former course2 so it obeyed this law1 and did go on4 ,why did the ball pull hard at the string as you swung it round8 ,because at each instant it was striving to obey this same law1 and to rush onward in a straight line4 ,the pull of the string was every moment fighting against that inclination1 and forcing the ball to move in a circle4 ,just such is the earth's movement in her yearly journey round the sun4 ,the string holding in the ball pictures the sun's attraction holding in the earth4 ,the pulling of the ball outward in order to continue its course in a straight line1 pictures the pulling of our earth each moment to break loose from the sun's attraction and to flee away into distant space4 ,for the earth is not at rest4 ,each tick of the clock she has sped onward over more than eighteen miles of her pathway through the sky4 ,every instant the sun is dragging1 with the tremendous force of his attraction1 to make her fall nearer to him4 ,every instant the earth is dragging with the tremendous force of her rapid rush1 to get away from him4 ,these two pullings so far balance each other1 or1 more strictly1 so far combine together1 that between the two she journeys steadily round and round in her nearly circular orbit4 ,if the sun pulled a little harder she would need to travel a little faster1 or she would gradually go nearer to him4 ,if the earth went faster1 and the sun's attraction remained the same as it is now1 she would gradually widen her distance4 ,indeed1 it would only be needful for the earth to quicken her pace to about five-and-twenty miles a second1 the sun's power to draw her being unchanged1 and she would then wander away from him for ever4 ,day by day we on our earth should travel farther and farther away1 leaving behind us all light1 all heat1 all life1 and finding ourselves slowly lost in darkness1 cold1 and death4 ,for what should we do without the sun8 ,all our light1 all our warmth1 come from him4 ,without the sun1 life could not exist on the earth4 ,plants1 herbage1 trees1 would wither2 the waters of rivers1 lakes1 oceans1 would turn to masses of ice2 animals and men would die4 ,our earth would soon be one vast1 cold1 forsaken tomb of darkness and desolation4 ,we may not think so1 but everything which moves1 circulates1 and lives on our planet is the child of the sun4 ,the most nutritious foods come from the sun4 ,the wood which warms us in winter is1 again1 the sun in fragments4 ,every cubic inch1 every pound of wood1 is formed by the power of the sun4 ,the mill which turns under the impulse of wind or water1 revolves only by the sun4 ,and in the black night1 under the rain or snow1 the blind and noisy train1 which darts like a flying serpent through the fields1 rushes along above the valleys1 is swallowed up under the mountains1 goes hissing past the stations1 of which the pale eyes strike silently through the mist1--in the midst of night and cold1 this modern animal1 produced by human industry1 is still a child of the sun4 ,the coal from the earth which feeds its stomach is solar work1 stored up during millions of years in the geological strata of the globe4 ,as it is certain that the force which sets the watch in motion is derived from the hand which has wound it1 so it is certain that all terrestrial power proceeds from the sun4 ,it is its heat which maintains the three states of bodies--solid1 liquid1 and gaseous4 ,the last two would vanish1 there would be nothing but solids2 water and air itself would be in massive blocks1--if the solar heat did not maintain them in the fluid state4 ,it is the sun which blows in the air1 which flows in the water1 which moans in the tempest1 which sings in the unwearied throat of the nightingale4 ,it attaches to the sides of the mountains the sources of the rivers and glaciers1 and consequently the cataracts and the avalanches are precipitated with an energy which they draw directly from him4 ,thunder and lightning are in their turn a manifestation of his power4 ,every fire which burns and every flame which shines has received its life from the sun4 ,and when two armies are hurled together with a crash1 each charge of cavalry1 each shock between two army corps1 is nothing else but the misuse of mechanical force from the same star4 ,the sun comes to us in the form of heat1 he leaves us in the form of heat2 but between his arrival and his departure1 he has given birth to the varied powers of our globe4 ,i have spoken before about the old-world notion that our earth was a fixed plain1 with the sun circling round her4 ,when the truth dawned slowly upon some great minds1 anxious only to know what really was the truth1 others made a hard struggle for the older and pleasanter mode of thinking4 ,it went with many sorely against the grain to give up all idea of the earth being the chief place in the universe4 ,also there was something bewildering and dizzying in the notion that our solid world is never for one moment still4 ,but truth won the victory at last4 ,men consented slowly to give up the past dream1 and to learn the new lesson put before them4 ,we still talk of the sun rising and setting1 and of the stars doing the same4 ,this is1 however1 merely a common form of speech1 which means just the opposite4 ,for instead of the sun and stars moving1 it is the earth which moves4 ,the earth has two distinct movements4 ,indeed1 ,i ought to say that she has three2 but we will leave all thought of the third for the present4 ,first1 she turns round upon her axis once in every twenty-four hours4 ,secondly1 she travels round the sun once in about every three hundred and sixty-five days and a quarter4 ,no wonder our ancestors were startled to learn that the world1 which they had counted so immovable1 was perpetually spinning like a humming-top1 and rushing through space like an arrow4 ,you may gain some clear notions as to the daily rising and setting of our sun1 with the help of an orange4 ,pass a slender knitting-needle through the orange1 from end to end1 and hold it about a yard distant from a single candle in a room otherwise darkened4 ,let the needle or axis slant somewhat1 and turn the orange slowly upon it4 ,the candle does not move2 but as the orange turns1 the candle-light falls in succession upon each portion of the yellow rind4 ,half of the orange is always in shade1 and half is always in light2 while at either side1 if a small fly were standing there1 he would be passing round out of shade into candle-light1 or out of candle-light into shade4 ,each spot on our earth moves round in turn into half-light1 full-light1 half-light1 and darkness2 or1 in other words1 has morning-dawn1 midday-light1 evening twilight1 and night4 ,each spot on our earth would undergo regularly these changes every twenty-four hours throughout the year1 were it not for another arrangement which so far affects this that the ,north and ,south ,poles are1 by turns1 cut off from the light during many months together4 ,thus the sun is in the center of the ,solar ,system1 turning slowly on his axis2 and the earth and the planets travel round him1 each spinning like a teetotum1 so as to make the most of his bright warm rays4 ,but for this spinning movement of the earth1 our day and night1 instead of being each a few hours long1 would each last six months4 ,you may notice that1 as you turn the orange steadily round1 the outside surface of the skin has to move much more slowly in those parts close to the knitting-needle1 than in those parts which bulge out farthest from it4 ,near the ,north and ,south ,poles the surface of our earth travels slowly round a very small circle in the course of twenty-four hours4 ,but at the equator every piece of ground has to travel about twenty-five thousand miles in the same time2 so that it rushes along at the rate of more than one thousand miles an hour4 ,a man standing on the earth at the equator is being carried along at this great speed1 not through the air1 for the whole atmosphere partakes of the same rapid motion1 but with the air1 round and round the earth's axis4 ,now about the other movement of the earth--her yearly journey round the sun4 ,while she moves1 the sun1 as seen from the earth1 seems to change his place4 ,first he is observed against a background of one group of stars1 then against a second1 then against a third4 ,not that the stars are visible in the daytime when the sun is shining1 but their places are well known in the heavens2 and also they can be noted very soon after he sets1 or before he rises1 so that the constellations nearest to him may each day be easily found out4 ,of course1 in old times the sun was thought to be really taking this journey among the stars1 and men talked of 8the sun's path0 in the heavens4 ,this path was named 8the ,ecliptic10 and we use the word still1 though we know well that the movements are not really his1 but ours4 ,as the earth's daily movement causes day and night1 so the earth's yearly movement causes spring1 summer1 autumn1 and winter4 ,a few pages back ,i mentioned1 in passing1 one slight yet important fact which lies at the root of this matter about the seasons4 ,the earth1 journeying round the sun1 travels with her axis slanting4 ,put your candle in the middle of the table1 and stand at one end1 holding your orange4 ,now let the knitting-needle1 with the orange upon it1 so slant that one end shall point straight over the candle1 towards the upper part of the wall at the farther end of the room4 ,call the upper end so pointing the ,north ,pole of your orange4 ,you will see that the candle-light falls chiefly upon the upper half of the orange2 and as you turn it slowly1 to picture day and night1 you will find that the ,north ,pole has no night1 and the ,south ,pole has no day4 ,that is summer in the northern hemisphere1 and winter in the southern4 ,walk round next to one side of the table1 towards the right hand1 taking care to let the knitting-needle point steadily still in exactly the same direction1 not towards the same spot1 for that would alter its direction as you move1 but towards the same wall4 ,stop1 and you will find the candle lighting up one-half of your orange1 from the ,north to the ,south ,poles4 ,turn it slowly1 never altering the slope of the axis1 and you will see that every part of the orange comes by turns under the light4 ,this is the ,autumnal ,equinox1 when days and nights all over the world are equal in length4 ,walk on to the other end of the table1 still letting the needle slope and point steadily as before4 ,now the candle-light will shine upon the lower or ,south ,pole1 and the ,north ,pole will be entirely in the shade4 ,this is summer in the southern hemisphere1 and winter in the northern4 ,pass on to the fourth side of the table1 and once more you will find it1 as at the second side1 equal light from ,north ,pole to ,south ,pole4 ,this will be the ,spring ,equinox4 ,it is an illustration that may be easily practiced4 ,but everything depends upon keeping the slant of the needle or axis unchanged throughout4 ,if it be allowed to point first to right1 and then to left1 first towards the ceiling1 and then towards the wall1 the attempt will prove a failure4 ,,chapter ,,iv4 ,,the ,,leading ,,members ,,of ,,our ,,family--,,first ,,group4 ,the chief distinction between stars and planets is1 as before said1 that the stars shine entirely by their own light1 while the planets shine chiefly1 if not entirely1 by reflected light4 ,the stars are suns2 mighty globes of glowing flame4 ,the planets simply receive the light of the sun1 and shine with a brightness not their own4 ,a lamp shines by its own light2 but a looking-glass1 set in the sun's rays and flashing beams in all directions1 shines by reflected light4 ,in a dark room it would be dark4 ,if there were no sun to shine upon ,mars or ,venus1 we should see no brightness in them4 ,the moon is like the planets in this4 ,she has only borrowed light to give1 and none of her own4 ,any one of the planets removed to the distance of the nearest fixed star1 would be invisible to us4 ,reflected light will not shine nearly so far as the direct light of a burning body4 ,there may be thousands or millions of planets circling round the stars--those great and distant suns--just as our brother-planets circle round our sun4 ,but it is impossible for us to see them4 ,the planets which we can see are close neighbors1 compared with the stars4 ,i do not mean that they are near in the sense in which we speak of nearness upon earth4 ,they are only near in comparison with what is so very much farther away4 ,for a while we must now leave alone all thought of the distant stars1 and try to gain a clear idea of the chief members of our own ,family ,circle--that family circle of which the sun is the head1 the center1 the source of life and warmth and light4 ,there are two ways in which astronomers group the planets of the ,solar ,system4 ,one way is to divide them into the ,inferior ,planets1 and the ,superior ,planets4 ,as the earth travels in her pathway round the sun1 two planets travel on their pathways round the sun nearer to him than ourselves4 ,if the pathway or orbit of our earth were pictured by a hoop laid upon the table1 with a ball in the center for the sun2 then those two planets would have two smaller hoops of different sizes within ours2 and the rest would have larger hoops of different sizes outside ours4 ,the two within are called inferior planets1 and the rest outside are called superior planets4 ,a round hoop would not make a good picture of an orbit4 ,for the yearly pathway of our earth is not in shape perfectly round1 but slightly oval2 and the sun is not exactly in the center1 but a little to one side of the center4 ,this is more or less the case with the orbits of all the planets4 ,but the laying of the hoops upon the table would give no bad idea of the way in which the orbits really lie in the heavens4 ,the orbits of all the chief planets do not slope and slant round the sun in all manner of directions4 ,they are placed almost in the same plane as it is called--or1 as we might say1 in the same flat4 ,in these orbits the planets all travel round in the same direction4 ,one may overtake a second on a neighboring orbit1 and get ahead of him1 but one planet never goes back to meet another4 ,in speaking of the orbits1 ,i do not mean that the planets have visible marked pathways through the heavens1 any more than a swallow has a visible pathway through the sky1 or a ship a marked pathway through the sea4 ,yet each planet has his own orbit1 and each planet so distinctly keeps to his own1 that astronomers can tell us precisely whereabouts in the heavens any particular planet will be1 at any particular time1 long years beforehand4 ,there is also another mode of grouping the planets1 besides dividing them into superior and inferior planets4 ,by this other mode we find two principal groups or quartets of planets1 separated by a zone or belt of a great many very small planets4 ,mercury4 ,first ,group ,venus4 ,earth4 ,mars4 ,the ,asteroids or ,planetoids4 ,jupiter4 ,second ,group ,saturn4 ,uranus4 ,neptune4 ,the first four are small compared with the last four1 though much larger than any in the belt of tiny ,asteroids4 ,it was believed at one time that a planet had been discovered nearer to the sun than ,mercury1 and the name ,vulcan was given to it4 ,but no more has been seen of ,vulcan1 and his existence is so doubtful that we must not count him as a member of the family without further information4 ,mercury is very much smaller than our ,earth4 ,the diameter of the earth is eight thousand miles1 but the diameter of ,mercury is only about three thousand miles--not even half that of the earth4 ,being so much nearer to the sun than ourselves1 the pulling of his attraction is much greater1 and this has to be balanced by greater speed1 or ,mercury would soon fall down upon the sun4 ,our distance from the sun is ninety-three millions of miles4 ,mercury's distance is only about one-third of ours2 and instead of traveling1 like the earth1 at the rate of eighteen miles each second1 ,mercury dashes headlong through space at the mad pace of twenty-nine miles each second4 ,it is a good thing the earth does not follow his example1 or she would soon break loose from the sun's control altogether4 ,the earth takes more than three hundred and sixty-five days1 or twelve months1 to journey round the sun in her orbit4 ,that is what we call 8the length of our year40 ,but ,mercury's year is only eighty-eight days1 or not quite three of our months4 ,no wonder6--when his pathway is so much shorter1 and his speed so much greater than ours4 ,so ,mercury has four years to one year on earth2 and a person who had lived on ,mercury as long as five earthly years1 would then be twenty years old4 ,the increased number of birthdays would scarcely be welcome in large families1 supposing we could pay a long visit there4 ,the sun1 as seen from ,mercury1 looks about four and a half times as large as from here2 the heat and glare being increased in proportion4 ,no moon has ever been found1 belonging to ,mercury4 ,the planet ,mercury is1 like the earth and the moon1 a globe of dark matter which only shines and is visible by the illumination of the solar light4 ,its motion round the central star1 which brings it sometimes between the sun and us1 sometimes in an oblique direction1 sometimes at right angles1 and shows us a part incessantly variable1 of its illuminated hemisphere1 produces in its aspect1 as seen in a telescope1 a succession of phases similar to those which the moon presents to us4 ,the cut represent the apparent variations of size and the succession of phases1 visible in the evening after sunset2 when the planet attains its most slender crescent1 it is in the region of its orbit nearest to the earth1 and passes between the sun and us2 then1 some weeks afterwards1 it emerges from the solar rays and passes again through the same series of phases in inverse order1 as we see them by reversing the figure4 ,illustration3 ,,phases ,,of ,,mercury ,,before ,,inferior ,,conjunction--,,evening ,,star4 ,venus1 the second inferior planet1 is nearly the same size as our earth4 ,seen from the earth1 she is one of the most brilliant and beautiful of all the planets4 ,her speed is three miles a second faster than ours1 and her distance from the sun is about two-thirds that of our own2 so that the orbit of ,venus lies half-way between the orbit of ,mercury and the orbit of the earth4 ,the day of ,venus is about half an hour shorter than ours4 ,her year is nearly two hundred and twenty-five days1 or seven and a half of our months4 ,one or two astronomers have fancied that they caught glimpses of a moon near ,venus2 but this is still quite doubtful1 and indeed it is believed to have been a mistake4 ,venus and ,mercury are only visible as morning and evening planets4 ,venus1 being farther from the sun1 does not go before and follow after him quite so closely as ,mercury1 and she is therefore the longer within sight4 ,when ,venus1 traveling on her orbit1 comes just between the sun and us1 her dark side is turned towards the earth1 and we can catch no glimpse of her4 ,when she reaches that part of her orbit which is farthest from us1 quite on the other side of the sun1 her great distance from us makes her light seem less4 ,but about half-way round on either side1 she shows exceeding brilliancy1 and that is the best view we can get of her4 ,seen through a telescope1 ,venus undergoes phases like those of ,mercury1 or of our moon4 ,that is to say1 we really have 8new ,venus10 8quarter ,venus10 8half ,venus10 8full ,venus10 and so on4 ,of all the luminaries in the heavens1 the sun and moon excepted1 the planet ,venus is the most conspicuous and splendid4 ,she appears like a brilliant lamp amid the lesser orbs of night1 and alternately anticipates the morning dawn1 and ushers in the evening twilight4 ,when she is to the westward of the sun1 in winter1 she cheers our mornings with her vivid light1 and is a prelude to the near approach of the break of day and the rising sun4 ,when she is eastward of that luminary1 her light bursts upon us after sunset1 before any of the other radiant orbs of heaven make their appearance2 and she discharges1 in some measure1 the functions of the absent moon4 ,the brilliancy of this planet has been noticed in all ages1 and has been frequently the subject of description and admiration both by shepherds and by poets4 ,the ,greek poets distinguished it by the name of ,phosphor1 8light-bringer10 when it rose before the sun1 and ,hesperus1 8the west10 when it appeared in the evening after the sun retired4 ,it is now generally distinguished by the name of the ,morning and ,evening ,star4 ,next to the orbit of ,venus comes the orbit of our own ,earth1 the third planet of the first group4 ,mars1 the fourth of the inner quartet1 but the first of the superior planets1 is a good deal smaller than ,venus or the earth4 ,the name ,mars1 from the heathen god of war1 was given on account of his fiery reddish color4 ,mars is better placed than ,venus for being observed from earth4 ,when he is at the nearest point of his orbit to us1 we see him full in the blaze of sunlight2 whereas ,venus1 at her nearest point1 turns her bright face away4 ,the length of the day of ,mars--or1 in other words1 the time he takes to turn upon his axis--is only forty minutes longer than that of earth4 ,mars' journey round the sun is completed in the course of six hundred and eighty-seven days1 not much less than two of our years4 ,his distance from the sun is about one hundred and forty millions of miles1 and his speed is fourteen miles a second4 ,we shall find1 with the increasing distance of each planet1 that the slower pace balances the lessened amount of the sun's attraction4 ,passing on from ,mars1 the last of the first group of planets1 we reach the belt of ,asteroids1 sometimes called ,planetoids1 ,minor ,planets1 or ,telescopic ,planets4 ,they are so tiny that ,mercury is a giant compared with the largest among them4 ,the zone of space containing all these little planets is more than a hundred millions of miles broad4 ,their orbits do not lie flat in almost the same plane1 but slant about variously in a very entangled fashion4 ,if a neat model were made of this zone1 with a slender piece of wire to represent each orbit1 it would be found impossible to lift up one wire without pulling up all the rest with it4 ,those asteroids lying nearest to the sun take about three of our years to travel round him1 and those lying farthest take about six of our years4 ,new members of the group are very often found4 ,the number of asteroids now known amounts to about three hundred and twenty4 ,ceres is estimated by ,professor ,barnard1 of the ,yerkes ,observatory1 ,chicago ,university1 to be six hundred miles in diameter4 ,vesta is about two hundred and fifty miles in diameter4 ,meta1 on the other hand1 is less than seventy-five miles4 ,there are some smaller ones that do not measure twenty miles in diameter1 and it is probable that there are many which are so small as to be absolutely invisible to the best telescopes1 and which measure only a few hundred rods in diameter4 ,twenty thousand ,vestas would be needed to make one globe equal to our earth in size4 ,are they worlds8 ,why not8 ,is not a drop of water1 shown in the microscope1 peopled with a multitude of various beings8 ,does not a stone in a meadow hide a world of swarming insects8 ,is not the leaf of a plant a world for the species which inhabit and prey upon it8 ,doubtless among the multitude of small planets there are those which must remain desert and sterile1 because the conditions of life 7of any kind7 are not found united4 ,but we can not doubt that on the majority the ever-active forces of nature have produced1 as in our world1 creations appropriate to these minute planets4 ,let us repeat1 moreover1 that for nature there is neither great nor little4 ,and there is no necessity to flatter ourselves with a supreme disdain for these little worlds2 for in reality the inhabitants of ,jupiter would have more right to despise us than we have to despise ,vesta1 ,ceres1 ,pallas1 or ,juno4 ,the disparity is greater between ,jupiter and the earth than between the earth and these planets4 ,a world of two1 three1 or four hundred miles in diameter is still a continent worthy to satisfy the ambition of a ,xerxes or a ,tamerlane4 ,,chapter ,v4 ,,the ,,leading ,,members ,,of ,,our ,,family--,,second ,,group4 ,leaving behind us the busy zone of planetoids1 hurrying round and round the sun in company1 we cross a wide gap1 and come upon a very different sight4 ,the distance from the sun which we have now reached is little less than four hundred and fifty millions of miles1 or about five times as much as the earth's distance2 and the sun in the heavens shows a diameter only one-fifth of that which we are accustomed to see4 ,slowly--yet not slowly--floating onwards through space1 in his far-off orbit1 we find the magnificent planet ,jupiter4 ,is eight miles each second slow progress8 ,compared with the wild whirl of little ,mercury1 or even compared with the rate of our own earth's advance1 we may count it so2 but certainly not1 compared with our notions of speed upon earth4 ,eight miles each second is five hundred times as fast as the swiftest express-train ever made by man4 ,no mean pace that for so enormous a body4 ,for ,jupiter is the very largest of all the members of the ,solar ,system except the sun himself--quite the eldest brother of the family4 ,his diameter is about eighty-five thousand miles1 his axis being nearly eleven times as long as that of earth4 ,though in proportion to his great bulk not nearly so heavy as our earth1 yet his bulk is so vast that more than twelve hundred earths would be needed to make one ,jupiter4 ,it must not1 however1 be forgotten that there is a certain amount of uncertainty about these measurements of ,jupiter4 ,he seems to be so covered with a dense atmosphere and heavy clouds that it is quite impossible for us to learn the exact size of the solid body within4 ,jupiter does not travel alone4 ,borne onwards with him1 and circling steadily around him1 are five moons2 the smallest with a probable diameter of about one hundred miles2 one about the same size as our own moon1 and the others all larger4 ,the nearest of the five1 though distant from the center of the planet over one hundred and twelve thousand miles1 revolves about him in twelve hours2 the second1 though farther from ,jupiter than our moon from the earth1 speeds round him in less than two of our days4 ,the most distant1 though over a million miles away1 takes scarcely seventeen days to accomplish its long journey4 ,jupiter and his moons make a little system by themselves--a family circle within a family circle4 ,like the smaller planets1 ,jupiter spins upon his axis2 and he does this so rapidly that1 notwithstanding his great size1 his day lasts only ten hours1 instead of twenty-four hours like ours4 ,but if ,jupiter's day is short1 his year is not4 ,nearly twelve of our years pass by before ,jupiter has traveled once completely round the sun4 ,so a native of earth who had just reached his thirty-seventh year1 would1 on ,jupiter1 be only three years old4 ,passing onward from ,jupiter1 ever farther and farther from the sun1 we leave behind us another vast and empty space--empty as we count emptiness1 though it may be that there is in reality no such thing as emptiness throughout the length and breadth of the universe4 ,the width of the gap which divides the pathway of ,jupiter from the pathway of his giant brother-planet ,saturn is nearly five times as much as the width of the gap separating the earth from the sun4 ,the distance of ,saturn from the sun is not much less than double the distance of ,jupiter4 ,with this great space in our rear1 we come upon another large and radiant planet1 the center1 like ,jupiter1 of another little system2 though it can only be called 8little0 in comparison with the much greater ,solar ,system of which it forms a part4 ,saturn's diameter is less than that of ,jupiter1 but the two come near enough to be naturally ranked together4 ,nearly seven hundred earths would be needed to make one globe as large as ,saturn4 ,but here again the dense and cloudy envelope makes us very uncertain about the planet's actual size4 ,saturn is like ,jupiter in being made of lighter materials than our earth2 and also in his rapid whirl upon his axis1 the length of his 8day0 being only ten and a half of our hours4 ,from ,jupiter's speed of eight miles each second1 we come down in the case of ,saturn to only five miles each second4 ,and ,jupiter's long annual journey looks almost short1 seen beside ,saturn's long journey of thirty earthly years4 ,a man aged sixty1 according to our fashion of reckoning time1 would on ,saturn have just kept his second birthday4 ,the system or family of ,saturn is yet more wonderful than that of ,jupiter4 ,not five only but eight moons travel ceaselessly round ,saturn1 each in its own orbit2 and in addition to the eight moons1 he has revolving round him three magnificent rings4 ,these rings1 as well as the moons1 shine1 not by their own brilliancy1 for they have none1 but by borrowed sunlight4 ,the farthest of the moons wanders in his lonely pathway about two millions of miles away from ,saturn4 ,the largest of them is believed to be about the same size as the planet ,mars4 ,of the three rings circling round ,saturn1 almost exactly over his equator1 the inside one is dusky1 purplish1 and transparent2 the one outside or over that is very brilliant2 and the third1 outside the second1 is rather grayish in hue4 ,another vast gap--more enormous than the last4 ,it is a wearisome journey4 ,from the orbit of ,jupiter to the orbit of ,saturn at their nearest points1 was five times as much as from the sun to the earth4 ,but from the orbit of ,saturn to the orbit of ,uranus1 the next member of the sun's family1 we have double even that great space to cross4 ,still1 obedient to the pulling of the sun's attractive power1 ,uranus wanders onward in his wide pathway round the sun1 at the rate of four miles a second4 ,eighty-four of our years make one year of ,uranus4 ,this planet has four moons1 and thus forms a third smaller system within the ,solar ,system2 but he may have other satellites also1 as yet undiscovered4 ,in size he is seventy-four times as large as our earth4 ,one more mighty chasm of nine hundred millions of miles1 for the same distance which separates the pathway of ,saturn from the pathway of ,uranus1 separates also the pathway of ,uranus from the pathway of ,neptune4 ,cold1 and dark1 and dreary indeed seems to us the orbit on which this banished member of our family circle creeps round the sun1 in the course of one hundred and sixty-five years1 at the sluggish rate of three miles a second4 ,on the planet ,saturn1 the quantity of light and heat received from the sun is not much more than a hundredth part of that which we are accustomed to receive on earth4 ,but by the time we reach ,neptune1 the great sun has faded and shrunk in the distance until to our eyes he looks only like an exceedingly brilliant and dazzling star4 ,we know little of this far-off brother1 ,neptune1 except that he is rather larger than ,uranus1 being one hundred and five times as big as the earth2 that he has at least one moon2 and also that1 like ,uranus1 he is made of materials lighter than those of earth1 but heavier than those of ,jupiter or ,saturn4 ,after all1 it is no easy matter to gain clear ideas as to sizes and distances from mere statements of 8so many miles in diameter10 and 8so many millions of miles away40 ,a 8million miles0 carries to the mind a very dim notion of the actual reality4 ,now if we can in imagination bring down all the members of the ,solar ,system to a small size1 keeping always the same proportions1 we may find it a help4 8,keeping the same proportions0 means that all must be lessened alike1 all must be altered in the same degree4 ,whatever the supposed size of the earth may be1 ,venus must be still about the same size as the earth1 ,saturn seven hundred times as large1 and so on4 ,also1 whatever the distance of the earth from the sun1 in miles1 or yards1 or inches1 ,mercury must still be one-third as far1 ,jupiter still five times as far1 and thus with the rest4 ,first1 as to size alone4 ,suppose the earth is represented by a small globe1 exactly three inches in diameter4 ,it will be a very small globe4 ,not only men and houses1 but mountains1 valleys1 seas1 will all have to be reduced to so minute a size1 as to be quite invisible to the naked eye4 ,fairly to picture the other members of the ,solar ,system1 in due proportion1 you will have them as follows3 ,mercury and ,mars will be balls smaller than the earth1 and ,venus nearly the same size of the earth4 ,uranus and ,neptune will be each somewhere about a foot in diameter4 ,saturn will be twenty-eight inches and ,jupiter thirty-two inches in diameter4 ,the sun will be a huge dazzling globe1 twenty-six feet in diameter4 ,no wonder he weighs seven hundred and fifty times as much as all his planets put together4 ,next let us picture the system more exactly on another and smaller scale4 ,first1 think of the sun as a brilliant globe1 about nine feet1 or three yards1 in diameter1 floating in space4 ,about one hundred yards from the sun travels a tiny ball1 not half an inch in diameter1 passing slowly round the sun--slowly1 because as sizes and distances are lessened1 speed must in due proportion be lessened also4 ,this is ,mercury4 ,about two hundred yards from the sun travels another tiny ball1 one inch in diameter4 ,this is ,venus4 ,nearly a quarter of a mile from the sun travels a third tiny ball1 one inch again in diameter2 and at a distance of two feet and a half from it a still smaller ball1 one quarter of an inch in diameter1 journeys round it and with it4 ,these are the earth and the moon4 ,about half as far again as the last-named ball1 travels another1 over half an inch in diameter4 ,this is ,mars4 ,then comes a wide blank space1 followed by a large number of minute objects1 no bigger than grains of powder1 floating round the sun in company4 ,these are the ,asteroids4 ,another wide blank space succeeds the outermost of them4 ,about one mile distant from the sun journeys a globe1 ten inches in diameter4 ,round him1 as he journeys1 there travel five smaller balls1 the largest of which is about the third of an inch in diameter4 ,their distances from the bigger globe vary from one and a third to twelve and a half feet4 ,these are ,jupiter and his moons4 ,nearly two miles distant from the sun journeys another globe1 about eight and a half inches in diameter4 ,eight tiny balls and three delicate rings circle round him as he moves4 ,these are ,saturn and his belongings4 ,about four miles distant from the sun journeys another globe1 four inches in diameter1 with four tiny balls accompanying him--,uranus and his moons4 ,lastly1 at a distance of six miles from the sun1 one more globe1 not much larger than the last1 with one tiny companion1 pursues his far-off pathway4 ,these proportions as to size and distance will serve to give a clear idea of the ,solar ,system4 ,,chapter ,,vi4 ,,the ,,moon4 ,come1 and let us pay a visit to the moon4 ,we seem to feel a personal interest in her1 just because she is1 in so peculiar a sense1 our own friend and close attendant4 ,the sun shines for us2 but1 then1 he shines for all the members of the ,solar ,system4 ,and the stars--so many as we can see of them--shine for us too2 but no doubt they shine far more brilliantly for other and nearer worlds4 ,the moon alone seems to belong especially to ourselves4 ,indeed1 we are quite in the habit of speaking about her as 8our moon40 ,rather a cold and calm friend1 some may think her1 sailing always serenely past1 whatever may be going on beneath her beams2 yet she has certainly proved herself constant and faithful in her attachment4 ,we have not very far to travel before reaching her1--merely about two hundred and forty thousand miles4 ,that is nothing1 compared with the weary millions of miles which we have had to cross to visit some members of our family4 ,a rope two hundred and forty thousand miles long would fold nearly ten times round the earth at the equator4 ,you know the earth's diameter--about eight thousand miles4 ,if you had thirty poles1 each eight thousand miles long1 and could fasten them all together1 end to end1 one beyond another1 you would have a rod long enough to reach from the earth to the moon4 ,let us take a good look at her before starting4 ,she is very beautiful4 ,that soft silvery light1 so unlike sunlight or gaslight1 or any other kind of light seen upon earth1 has made her the darling of poets and the delight of all who love nature4 ,little children like to watch her curious markings1 and to make out the old man with his bundle of sticks1 or the eyes1 nose1 and mouth of the moon--not dreaming what those markings really are4 ,and in moods of sadness1 how the pure calm moonlight seems to soothe the feelings6 ,who would suppose that the moon's beauty is the beauty rather of death than of life8 ,illustration3 ,,appearance ,,of ,,the ,,full ,,moon4 ,the stars have not much chance of shining through her bright rays4 ,it is well for astronomers that she is not always at the full4 ,but when she is1 how large she looks--quite as large as the sun1 though in reality her size1 compared with his1 is only as a very small pin's head compared with a school globe two feet in diameter4 ,her diameter is little more than two thousand miles1 or one quarter that of our earth2 and her whole surface1 spread out flat1 would scarcely equal ,north and ,south ,america1 without any of the surrounding islands4 ,the reason she looks the same size as the sun1 is that she is so very much nearer4 ,the sun's distance from us is more than one-third as many millions of miles as the moon's distance is thousands of miles4 ,this makes an enormous difference4 ,we call our friend a 8moon10 and say that she journeys round the earth1 while the earth journeys round the sun4 ,this is true1 but it is only part of the truth4 ,just as certainly as the earth travels round the sun1 so the moon also travels round the sun4 ,and just as surely as the earth is a planet1 so the moon also is a planet4 ,it is a common mode of expression to talk about 8the earth and her satellite40 ,a no less correct1 if not more correct1 way would be to talk of ourselves as 8a pair of planets10 journeying round the same sun1 each pulled strongly towards him1 and each pulling the other with a greater or less attraction1 according to her size and weight4 ,for the sun actually does draw the moon with more force than that with which the earth draws her4 ,only as he draws the earth with the same sort of force1 and nearly in the same degree1 he does not pull them apart4 ,the moon1 like the other planets1 turns upon her axis4 ,she does this very slowly1 however2 and most singularly she takes exactly the same time to turn once upon her axis that she does to travel once round the earth4 ,the result of this is1 that we only see one face of the moon4 ,if she turned upon her axis1 and journeyed round the earth in two different lengths of time1 or if she journeyed round us and did not turn upon her axis at all1 we should have views of her on all sides1 as of other planets4 ,but as her two movements so curiously agree1 it happens that we always have one side of the moon towards us1 and never catch a glimpse of the other side4 ,and now we are ready to start on our journey of two hundred and forty thousand miles4 ,an express train1 moving ceaselessly onward night and day1 at the rate of sixty miles an hour1 would take us there in about five months and a half4 ,but no line of rails has ever yet been laid from the earth to the moon1 and no 8,flying ,dutchman0 has ever yet plied its way to and fro on that path through the heavens4 ,not on the wings of steam1 but on the wings of imagination1 we must rise aloft4 ,come--it will not take us long4 ,we shall pass no planets or stars on the road1 for the moon lies nearer to us than any other of the larger heavenly bodies4 ,far1 far behind us lies the earth1 and beneath our feet1 as we descend1 stretch the broad tracts of moonland4 ,for 8downward0 now means towards the moon1 and away from the distant earth4 ,what a strange place we have reached6 ,the weird1 ghastly stillness of all around1 and the glaring1 dazzling1 cloudless heat1 strike us first and most forcibly4 ,nothing like this heat have we ever felt on earth4 ,for the close of the moon's long day--on this side of its globe--is approaching1 and during a whole fortnight past the sun's fierce rays have been beating down on these shelterless plains4 ,talk of sweltering tropics on earth6 ,what do you call this heat8 ,look at the thermometer3 how the quicksilver is rising6 ,well1 that is not a common thermometer which we have brought with us4 ,the mercury has stopped--three hundred degrees above boiling water6 ,not a cloud to be seen overhead2 only a sky of inky blackness1 with a blazing sun1 and thousands of brilliant stars1 and the dark body of our own earth1 large and motionless1 and rimmed with light4 ,seen from earth1 sun and moon look much the same size2 but seen from the moon1 the earth looks thirteen times as large as our full moon4 ,not even a little mistiness in the air to soften this fearful glare6 ,air6 why1 there is no air2 at least not enough for any human being to breathe or feel4 ,if there were air1 the sky would be blue1 not black1 and the stars would be invisible in the daytime4 ,it looks strange to see them now shining beside the sun4 ,and then1 this deadly stillness6 ,not a sound1 not a voice1 not a murmur of breeze or water4 ,how could there be8 ,sound can not be carried without air1 and of air there is none4 ,as for breeze--wind is moving air1 and where we have no air we can have no wind4 ,as for water--if there ever was any water on the moon1 it has entirely disappeared4 ,we shall walk to and fro vainly in search of it now4 ,no rivers1 no rills1 no torrents in those stern mountain ramparts rising on every side4 ,all is craggy1 motionless1 desolate4 ,how very1 very slowly the sun creeps over the black sky6 ,and no marvel1 since a fortnight of earth-time is here but one day1 answering to twelve hours upon earth4 ,can not we find shelter somewhere from this blazing heat8 ,yonder tall rock will do1 casting a sharp shadow of intense blackness4 ,we never saw such shadows upon earth4 ,there the atmosphere so breaks and bends and scatters about the light1 that outlines of shadows are soft and hazy1 even the clearest and darkest of them1 compared with this4 ,when will the sun go down8 ,but he is well worth looking at meanwhile4 ,how magnificent he appears1 with his pure radiant photosphere1 fringed by a sierra of dazzling pink and white1 orange and gold1 purple and blue4 ,for here no atmosphere lies between to blend all into yellow-white brightness4 ,and how plainly stand out those prominences or tongues of tinted flame1 not merely rose-colored1 as seen from earth1 but matching the sierra in varying hues2 while beyond spreads a gorgeous belt of pink and green1 bounded by lines and streams of delicate white light1 reaching far and dying slowly out against the jet background4 ,the black spots on the face of the sun are very distinct1 and so also are the brilliant facul4 ,we must take a look around us now at moonland1 and not only sit gazing at the sun1 though such a sky may well enchain attention4 ,how unlike our earthly landscapes6 ,no sea1 no rivers1 no lakes1 no streams1 no brooks1 no trees1 bushes1 plants1 grass1 or flowers2 no wind or breeze2 no cloud or mist or thought of possible rain2 no sound of bird or insect1 of rustling leaves or trickling water4 ,nothing but burning1 steadfast1 changeless glare1 contrasting with inky shadows2 sun and earth and stars in a black heaven above2 silent1 desolate mountains and plains below4 ,for though we stand here upon a rough plain1 this moon is a mountainous world4 ,ranges of rugged hills stretch away in the distance1 with valleys lying between--not soft1 green1 sloping1 earthly valleys1 but steep gorges and precipitous hollows1 all white dazzle and deep shade4 ,but the mountains do not commonly lie in long ranges1 as on earth4 ,the surface of the moon seems to be dented with strange round pits1 or craters1 of every imaginable size4 ,we had a bird's-eye view of them as we descended at the end of our long journey moonward4 ,in many parts the ground appears to be quite honeycombed with them4 ,here are small ones near at hand1 and larger ones in the distance4 ,the smaller craters are surrounded by steep ramparts of rock1 the larger ones by circular mountain-ranges4 ,we have nothing quite like them on earth4 ,are they volcanoes8 ,so it would seem2 only no life1 no fire1 no action1 remain now4 ,all is dead1 motionless1 still4 ,is this verily a blasted world8 ,has it fallen under the breath of ,almighty wrath1 coming out scorched and seared8 ,is it simply passing through a certain burnt-out1 chilled phase of existence1 through which other planets also pass1 or will pass1 at some stage of their career8 ,who can tell8 ,we will move onward1 and look more closely at that towering mass of rugged rocks1 beyond which the sun will by and by go down4 ,long jetty shadows lie from them in this direction4 ,no wonder astronomers on earth can through their telescopes plainly see these black shadows contrasting with the glaring brightness on the other side4 ,a 8mass of rocks0 ,i have said2 but as1 with our powers of rapid movement1 we draw near1 we find a range of craggy mountains sweeping round in a vast circle4 ,such a height in ,switzerland would demand many hours of hard climbing4 ,but on this small globe attraction is a very different matter from what it is on earth2 our weight is so lessened that we can leap the height of a tall house without the smallest difficulty4 ,no chamois ever sprang from peak to peak in his native ,switzerland with such amazing lightness as that with which we now ascend these mighty rocks4 ,illustration3 ,,one ,,form ,,of ,,lunar ,,crater4 ,ha6 what a depth on the other side6 ,we stand looking down into one of the monster craters of the moon4 ,a sheer descent of at least eleven thousand feet would land us at the bottom4 ,why1 ,mont ,blanc itself is only about fifteen thousand feet in height4 ,and what a crater6 ,fifty-six miles across in a straight line1 from here to the other side1 with these lofty rugged battlements circling round1 while from the center of the rough plain below a sharp1 cone-shaped mountain rises to about a quarter of the height of the surrounding range4 ,it is a grand sight2 peak piled upon peak1 crag upon crag1 sharp rifts or valleys breaking here and there the line of the narrow1 uplifted ledge2 all wrapped in silent and desolate calm4 ,there are many such craters as this on the moon1 and some much larger4 ,the sun slowly nears his setting1 and sinks behind the opposite range4 ,how we shiver6 ,the last ray of sunlight has gone and already the ground is pouring out its heat into space1 unchecked by the presence of air or clouds4 ,the change takes place with marvelous quickness4 ,a deadly chill creeps over all around4 ,a whole fortnight of earth-time must pass before the sun's rays will again touch this spot4 ,verily the contrasts of climate in the moon1 during the twelve long days and nights which make up her year1 are startling to human notions4 ,but though the sun is gone we are not in darkness4 ,the stars shine with dazzling brightness1 and the huge body of the earth1 always seeming to hang motionless at one fixed point in the sky1 gives brilliant light1 though at present only half her face is lit up and half is in shadow4 ,still her shape is plainly to be seen1 for she has ever round her a ring of light1 caused by the gathered shining of stars as they pass behind her thick atmosphere4 ,she covers a space on the sky more than a dozen times as large as that covered by the full moon in our sky4 ,illustration3 ,,the ,,earth ,,as ,,seen ,,from ,,the ,,moon4 ,it would be worth while to stay here and watch the half-earth grow into magnificent full-earth4 ,but the cold is becoming fearful--too intense for even the imagination to endure longer4 ,what must be the state of things on the other side of the moon1 where there is no bright earth-light to take the place of the sun's shining1 during the long two weeks' night of awful chill and darkness8 ,it seems probable that a building on the moon would remain for century after century just as it was left by the builders4 ,there need be no glass in the windows1 for there is no wind and no rain to keep out4 ,there need not be fireplaces in the rooms1 for fuel can not burn without air4 ,dwellers in a city in the moon would find that no dust can rise1 no odors be perceived1 no sounds be heard4 ,man is a creature adapted for life in circumstances which are very narrowly limited4 ,a few degrees of temperature1 more or less2 a slight variation in the composition of air1 the precise suitability of food1 make all the difference between health and sickness1 between life and death4 ,looking beyond the moon1 into the length and breadth of the universe1 we find countless celestial globes1 with every conceivable variety of temperature and of constitution4 ,amid this vast number of worlds with which space teems1 are there any inhabited by living beings8 ,to this great question science can make no response save this3 ,we can not tell4 ,time for us to wend our way homewards from this desolate hundred-fold arctic scene4 ,we have more to learn by and by about our friend and companion4 ,for the present--enough4 ,,chapter ,,vii4 ,,visitors4 ,we come next to the very largest members of our ,solar ,system4 ,from time to time in past days--and days not very long past either--people were startled by the sight of a long-tailed star1 moving quickly across the sky1 called a comet4 ,we see such long-tailed stars still1 now and then2 but their appearance no longer startles us4 ,it is hardly surprising1 however1 that fears were once felt4 ,the great size and brilliancy of some of these comets naturally caused large ideas to be held as to their weight1 and the general uncertainty about their movements naturally added to the mysterious notions afloat with respect to their power of doing harm4 ,a collision between the earth and a comet seemed no unlikely event2 and if it happened--what then8 ,why1 then1 of course1 the earth would be overpowered1 crushed1 burnt up1 destroyed4 ,so convinced were many on this point that the sight of a comet and the dread of the coming 8end of the world0 were fast bound together in their minds4 ,even when astronomers began to understand the paths of some of the comets1 and to foretell their return at certain dates1 the old fear was not quickly laid to rest4 ,so late as the beginning of the present century1 astronomers having told of an approaching comet1 other people added the tidings of an approaching collision4 8,if a collision1 then the end of the world10 was the cry2 and one worthy family1 living and keeping a shop in a well-known town on the south coast of ,england1 packed up and fled to ,america--doubtless under full belief that the destruction of the ,old ,world would not include the destruction of the ,new4 ,the nature of these singular bodies is somewhat better known in the present day2 yet even now1 among all the members of the ,solar ,system1 they are perhaps the ones about which we have most to learn4 ,the nucleus1 or bright and star-like spot1 which1 with the surrounding coma or 8hair10 we sometimes call the 8head0 of the comet1 is the densest and heaviest part of the whole4 ,the comets are of immense size1 sometimes actually filling more space than the sun himself1 and their tails stream often for millions of miles behind them2 nevertheless1 they appear to be among the lightest of the members of the ,solar ,system4 ,this excessive lightness greatly lessens the comet's power of harm-doing4 ,in the rebound from all the old exaggerated fears1 men laughed at the notion of so light and delicate a substance working any injury whatever1 and even declared that a collision might take place without people on earth being aware of the fact4 ,it is now felt that we really know too little about the nature of the said substance to be able to say what might or might not be the result of a collision4 ,a certain amount of injury to the surface of the earth might possibly take place4 ,but of the 8end of the world10 as likely to be brought about by any comet in existence1 we may safely banish all idea4 ,the word 8comet0 means 8a hairy body10 the name having been given from the hairy appearance of the light around the nucleus4 ,about seventeen hundred different comets have been seen at different times by men--some large1 some small2 some visible to the naked eye1 but most of them only visible through telescopes4 ,these hundreds are1 there is no doubt1 but a very small number out of the myriads ranging through the heavens4 ,if you were seated in a little boat in mid-ocean1 counting the number of fishes which in one hour passed near enough in the clear water for your sight to reach them1 you might fairly conclude1 even if you did not know the fact1 that for every single fish which you could see1 there were tens of thousands which you could not see4 ,reasoning thus about the comets1 as we watch them from our earth-boat in the ocean of space1 we feel little doubt that for each one which we can see1 millions pass to and fro beyond reach of our vision4 ,indeed1 so long ago as the days of ,kepler1 that great astronomer gave it as his belief that the comets in the ,solar ,system1 large and small1 were as plentiful as the fishes in the sea4 ,and all that modern astronomers can discover only tends to strengthen this view4 ,why should the comets be called 8visitors80 ,i call them so simply because many of them are visitors4 ,some1 it is true1 belong to the ,solar ,system4 ,but even in their case1 strong doubts are felt whether they were not once visitors from a distance1 caught in the first instance by the attraction of one of the larger planets1 and retained thenceforward1 for a time at least1 by the strong attraction of the sun4 ,illustration3 ,,passage ,,of ,,the ,,earth ,,and ,,the ,,moon ,,through ,,the ,,tail ,,of ,a ,,comet4 ,every comet1 like every planet1 has his own orbit or pathway in the heavens1 though the kind of orbit varies with different comets4 ,there are1 first1 those comets which travel round and round the sun in 8closed orbits0--that is1 in a ring with joined ends4 ,only the ring is always oval1 not round4 ,there are1 secondly1 those which travel in an orbit which may be closed2 but if so1 the oval is so long and narrow1 and the farther closed end is at so great a distance1 that we can not speak certainly4 ,there are1 thirdly1 those which decidedly are mere visitors4 ,they come from the far-off star-depths1 flash once with their brilliant trains of light through our busy ,solar ,system1 causing some little excitement by the way1 and go off in another direction1 never to return4 ,only a small part of the orbits of these comets can be seen from earth2 but by careful attention astronomers learn something of the shape of the curve in which they travel4 ,it is in that way possible to calculate1 sometimes certainly1 and sometimes uncertainly1 whether a comet may be expected to return1 or whether we have seen him for the first and the last time4 ,by looking at part of a curve1 the rest of which is hidden from us1 we are able to judge whether that part belongs to a circle or an oval1 or whether the two ends pass away in different directions1 and do not join4 ,the comets1 whether members of our family circle or visitors from a distance1 are altogether very perplexing4 ,they are often extremely large1 yet they are always extremely light4 ,they reflect the sun's brightness like a planet1 yet in some measure they seem to shine by their own light1 like a star4 ,they obey the attraction of the sun1 yet he appears to have a singular power of driving the comets' tails away from himself4 ,for1 however rapidly the comet may be rushing round the sun1 and however long the tail may be1 it is almost always found to stream in an opposite direction from the sun4 ,an exception to this rule was seen in the case of a certain comet with two tails1 one of which did actually point towards the sun2 but the inner tail may have been only a 8jet0 of unusual length1 like in kind to the smaller jets often thus poured out from the nucleus4 ,very curious changes take place in comets as they journey1 especially as they come near the sun4 ,one was seen in the course of a few days to lose all his hair1 and also his tail4 ,another was seen to break into two pieces1 both of which pieces at last disappeared4 ,sometimes the one tail divides into two tails4 ,traveling1 as the comets do1 from intense cold into burning heat1 they are very much affected by the violent change of climate4 ,for the paths of the comets are such long ovals1 or ellipses1 that1 while they approach the sun very closely in one part of their 8year10 they travel to enormous distances in the other part4 8,halley's ,comet10 which takes seventy-six of our years to journey round the sun1 comes nearer to him than ,venus1 and goes farther away from him than ,neptune4 ,as this comet draws gradually closer1 he has to make up for the added pull of the sun's increasing attraction by rushing onward with greater and greater rapidity1 till he whirls madly past the sun1 and then1 with slowly slackening speed1 journeys farther and farther away1 creeps at length lazily round the farther end of his orbit in the chill1 dark1 neighborhood of ,neptune1 and once more travels towards the sun with growing haste4 8,encke's ,comet0 has a year of only three and a half of our years1 so he may be said to live quite in our midst4 ,but many comets travel much farther away than the one named after ,halley4 ,it is calculated of some that1 if they ever return at all1 it can not be for many hundreds of years4 ,illustration3 ,,passage ,,of ,,the ,,comet ,,of #ahdc ,,close ,,to ,,the ,,sun 7,,february #bg,,th1 #aj ,,hours1 #bi ,,minutes47 8,newton's ,comet10 seen about two centuries ago1 has a journey to perform of such length that he is not expected again to appear for several thousand years4 ,yet1 at the nearest point in his orbit1 he approached the sun so closely1 that the heat which he endured was about two thousand times that of red-hot iron4 ,changes were seen to be taking place in his shape1 as he drew near to the sun1 and disappeared4 ,four days he was hidden in the sun's rays4 ,he vanished1 with a tail streaming millions of miles behind him4 ,he made his appearance again with a tail streaming millions of miles in front of him4 ,but how this wonderful movement took place is beyond man's power to explain4 ,the comet of #ahdc was one of the most attractive seen during the present century4 ,it was first observed in ,march1 and it appeared with a suddenness which had quite a startling effect4 ,it was an imposing object in the southern regions4 ,the comet was seen in ,italy on the #bhth of ,february2 at ,washington1 on the #fth of ,march2 at ,oporto1 on the #adth2 but owing to unfavorable weather1 it was not visible in ,england1 or any of the northern countries of ,europe1 previous to the #agth4 ,a little after sunset on that day the tail was observed in the western sky1 but the head had already sunk below the horizon4 ,the whole of the comet appeared on the following evenings for a short time1 for it was traveling away from the sun with great velocity1 having doubled the solar orb before it became visible2 and about the beginning of ,april it finally disappeared4 ,the appearance of this startling stranger1 as observed at ,washington1 is thus described by ,lieutenant ,maury1 of the ,hydrographical ,office in that city3 8,on ,monday morning1 ,march #fth1 our attention was called to a paragraph in the newspapers1 stating that a comet was visible near the sun at midday with the naked eye4 ,the sky was clear2 but not being able to discover any thing with the unassisted eye1 recourse was had to the telescope1 but with no better success4 ,about sunset in the evening1 the examination was renewed with great diligence1 but to no purpose4 ,the last faint streak of day gilded the west2 beautiful and delicate fleeces of cloud curtained the bed of the sun2 the upper sky was studded with stars1 and all hopes of seeing the comet that evening had vanished4 ,soon after we had retired1 the officer of the watch announced its appearance in the west4 ,the phenomenon was sublime and beautiful4 ,the needle was greatly agitated1 and a strongly marked pencil of light was streaming up from the path of the sun in an oblique direction to the southward and eastward2 its edges were parallel4 ,it was #cj long4 ,stars could be seen twinkling through it1 and no doubt was at first entertained that this was the tail of the comet40 ,the tail1 as seen in northerly countries1 spread over an arc of the heavens of about #dj2 but in southern latitudes it extended to from #fj to #gj4 ,it had an absolute length of two hundred millions of miles2 so that1 had it been coiled around the earth like a serpent1 it would have girdled it eight thousand times at the equator4 ,this comet approached still nearer the sun than that of ,newton1 and must therefore have been exposed to a heat of greater intensity4 ,its center is computed to have been within a hundred thousand miles of the solar surface2 and according to ,sir ,john ,herschel's calculations1 it was then exposed to a heat equal to that which would be received by an equal portion of the earth's surface1 if it were subject to the influence of forty-seven thousand suns1 placed at the common distance of the actual sun4 ,it is difficult to conceive how a flimsy substance in such circumstances could escape being entirely dissipated4 ,but such was its velocity that it wheeled round the sun in less than two hours4 ,the general question of the probability and the consequences of a collision with a comet may be legitimately entertained4 ,with reference to the first point1 it can not be denied that collision is possible2 but1 at the same time1 it is so extremely improbable that it may be safely dismissed from apprehension4 ,the fact of such an event not having been experienced in the known course of terrestrial history is surely some guarantee against its occurrence4 ,another may be found in the small volume of the earth and of comets when compared with the immensity of space in which they move4 ,according to the well-understood principles of probabilities1 ,arago has calculated that1 upon the appearance of a new comet1 the odds are as #bha1jjj1jjj to #a1 that it will not strike against our globe4 ,but even supposing collision to occur1 all that we know of the constitution of comets justifies the conclusion that the encounter would involve no terrestrial convulsion1 nor any result incompatible with full security to life and happiness4 ,so much for the largest members of our circle--largest1 though lightest2 members some1 visitors others4 ,now we turn to the smallest4 ,,chapter ,,viii4 ,,little ,,servants4 ,if you walk out any night after dark1 and watch the bright stars shining in a clear sky--shining as they have done for ages past--you will probably see1 now and then1 a bright point of light suddenly appear1 dart along a little distance1 and as suddenly vanish4 ,that which you have seen was not the beginning of a story1 but in ninety-nine cases out of a hundred it was the end of a story4 ,the little shooting-star was in existence long before you saw him1 whirling through space with millions of little companions4 ,but he has left them all1 and dropped to earth4 ,he is a shooting-star no longer4 ,if such a journey to the moon as the one described two chapters back were indeed possible1 the voyage aloft would hardly be so easily and safely performed as is there taken for granted4 ,putting aside the thought of other difficulties1 such as lack of conveyance and lack of air1 there would be the danger of passing through a very considerable storm of missiles--a kind of 8celestial cannonade0--which1 to say the least1 would prove very far from agreeable4 ,these 8starlets0 and 8meteor planets10 as they have been called1 are not visible in a normal condition1 because of their minuteness4 ,but on entering our atmosphere they are rendered luminous1 owing to the heat evolved by the sudden and violent compression of the air in front of the moving body4 ,according to this view1 shooting-stars1 which simply dart across the heavens1 may be regarded as coming within the limits of the atmosphere1 and carried out of it again1 by their immense velocity1 passing on in space4 ,meteoric showers may result from an encounter with a group of these bodies1 while arolites are those which come so far within the sphere of the earth's attraction as to fall to its surface4 ,more than two thousand years ago the ,greeks venerated a famous stone which fell from the heavens on the river gos4 ,illustration3 ,,meteor ,,emerging ,,from ,,behind ,a ,,cloud 7,,nov4 #bc1 #ahgg74 ,it will scarcely be believed what numbers of these shooting-stars or meteorites constantly fall to the earth4 ,as she travels on her orbit1 hurrying along at the rate of nineteen miles each second1 she meets them by tens of thousands4 ,they too1 like the earth1 are journeying round the great center of our family4 ,but they are so tiny1 and the earth by comparison is so immense1 that her strong attraction overpowers one after another1 drags it from its pathway1 and draws it to herself4 ,and then it falls1 flashing like a bright star across the sky1 and the little meteorite has come to his end4 ,his myriads of companions1 hastening still along their heavenly track--for the meteorites seem to travel commonly in vast flocks or companies--might1 had they sense1 mourn in vain for the lost members of their family4 ,any one taking the trouble to watch carefully some portion of the sky after dark1 may expect to see each hour about four to eight of these shooting-stars--except in the months of ,august and ,november1 when the number is much larger4 ,about six in an hour does not sound a great deal4 ,but that merely means that there have been six in one direction1 and near enough for you to see4 ,somebody else1 watching1 may have seen six in another direction2 and somebody else1 a few miles away1 may have seen six more4 ,it is calculated that1 in the course of every twenty-four hours1 about four hundred millions of meteorites fall to earth1 including those visible only through telescopes4 ,this is rather startling4 ,what if you or ,i should some day be struck by one of these solid1 hard little bodies1 darting as they do towards earth with speed swifter than that of a cannon-ball8 ,true1 they are not really stars1 neither are they really planets4 ,but they are1 to say the least1 often much larger than a cannon-ball1 and a cannon-ball can destroy life4 ,four hundred millions every twenty-four hours6 ,does it not seem singular that we do not see them constantly dropping to the ground8 ,the truth is1 we should see them1 and feel them too1 and dire would be the danger to human life1 but for a certain protecting something folded round this earth of ours to ward off the peril4 ,that 8something0 is the earth's atmosphere4 ,but for the thick1 soft1 strong1 elastic air through which the meteorites have to pass1 they would fall with fearful violence1 often doing terrible mischief4 ,as it is1 we are guarded4 ,the shooting-star1 drawn by the earth's attraction1 drops into her atmosphere1 darting with tremendous speed4 ,in consequence of this speed and the resistance of the air1 it catches fire4 ,that is when we first see it4 ,the meteorites are believed to appear at a height of about seventy miles1 and to disappear at a height of about fifty miles4 ,so that1 in one instant's flash1 the shooting-star has traveled some twenty miles toward us4 ,then the light goes out4 ,the little meteorite is burnt4 ,it falls to earth still2 but only as fine dust1 sinking harmlessly downward4 ,the meteorites do not always vanish so quickly4 ,now and then a larger one--too large to be rapidly burnt--does actually reach the ground4 ,if any man were struck by such a stone he would undoubtedly be killed4 ,when meteorites thus fall to earth they are usually called arolites4 ,some are found no bigger than a man's fist1 while others much exceed this size4 ,there is one1 kept carefully in the ,british ,museum1 which weighs three tons and a half2 and we hear of another1 lying in ,south ,america1 between seven and eight feet in length4 ,such a sky-visitant would be very unwelcome in any of our towns4 ,we must remember that1 whatever size an arolite may be when it reaches the earth1 it must have been far greater when journeying round the sun1 since a good part of it has been burnt away during its rush downward through the earth's atmosphere4 ,meteors1 or bolides1 or fireballs1 are of much the same nature as meteorites2 but they are larger1 longer to be seen1 and slower in movement4 ,also1 it is not uncommon for them to burst with a loud explosion4 ,early in the present century such a meteor visited ,normandy4 ,it exploded with a noise like the roll of musketry1 scattering thousands of hot stones over a distance of several miles4 ,a great number of them were collected1 still smoking4 ,the largest of these stones weighed no less than twenty pounds4 ,happily no one seems to have been injured4 ,other such falls have taken place from time to time4 ,sometimes bright1 slowly-moving meteors have been seen1 looking as large as the moon4 ,a remarkable fireball appeared in ,england on ,november #f1 #ahfi4 ,this fireball was extensively seen from different parts of the island1 and by combining and comparing these observations1 we obtain accurate information as to the height of the object and the velocity with which it traveled4 ,it appears that this meteor commenced to be visible at a point ninety miles above ,frome1 in ,somersetshire1 and that it disappeared at a point twenty-seven miles over the sea1 near ,st4 ,ives1 in ,cornwall4 ,the whole length of its course was about #agj miles1 which was performed in a period of five seconds1 thus giving an average velocity of thirty-four miles a second4 ,a remarkable feature in the appearance which this fireball presented was the long1 persistent streak of luminous cloud1 about fifty miles long and four miles wide1 which remained in sight for fully fifty minutes4 ,we have in this example an illustration of the chief features of the phenomena of a shooting-star presented on a very grand scale4 ,it is1 however1 to be observed that the persistent luminous streak is not a universal1 nor1 indeed1 a very common characteristic of a shooting-star4 ,if we may liken comets to the fishes of the ,solar ,system--and in their number1 their speed1 their varying sizes1 their diverse motions1 they may be fairly so likened--we may perhaps speak of the meteorites as the animalcula of the ,solar ,system4 ,for1 in comparison with the planets1 they are1 in the matter of size1 as the animalcula of our ponds in comparison with human beings4 ,in point of numbers they are countless4 ,take a single drop of water from some long-stagnant pond1 and place it under a powerful microscope4 ,you will find it to be full of life1 teeming with tiny animals1 darting briskly to and fro4 ,the drop of water is in itself a world of living creatures1 though the naked eye of man could never discover their existence4 ,so with the meteorites4 ,there is good reason to believe that the ,solar ,system fairly teems with them4 ,we talk of 8wide gaps of empty space10 between the planets2 but how do we know that there is any such thing as empty space to be found throughout all the sun's domain8 ,not only are the meteorites themselves countless1 a matter easily realized1 but the families or systems of meteorites appear to be countless also4 ,they1 like the systems of ,jupiter and ,saturn1 are each a family within a family--a part of the ,solar ,system1 and yet a complete system by themselves4 ,each circles round the sun1 and each consists of millions of tiny meteorites4 ,when ,i say 8tiny10 ,i mean it of course only by comparison with other heavenly bodies4 ,many among them may possibly be hundreds of feet and even more in diameter1 but the greater proportion appear to be much smaller4 ,it is not impossible that multitudes beyond imagination exist1 so small in size that it is impossible we should ever see them1 since their dying flash in the upper regions of our atmosphere would be too faint to reach our sight4 ,the earth1 traveling on her narrow orbit round the sun1 crosses the track of about one hundred of these systems1 or rings4 ,sometimes she merely touches the edge of a ring1 and sometimes she goes into the very thick of a dense shower of meteorites4 ,twice every year1 for instance1 on the #ajth of ,august and the #aath of ,november1 the earth passes through such a ring1 and very many falling stars may be seen on those nights4 ,numbers of little meteorites1 dragged from their orbits and entangled in the earth's atmosphere1 like a fly caught in a spider's web1 give their dying flash1 and vanish4 ,it used to be supposed that the ,august and ,november meteorites belonged to one single system2 but now they are believed to be two entirely distinct systems4 ,illustration3 ,,the ,,great ,,shower ,,of ,,shooting-,,stars1 ,,november #bg1 #ahgb4 ,the comet discovered on ,february #bg1 #ahbg1 by ,biela1 and ten days later at ,marseilles by ,gambart1 who recognized that it was the same as that of #aggb and #ahje1 returned six and a half years later1 in #ahcb4 ,in fact it crossed1 as we have seen1 the plane of the terrestrial orbit at the respectable distance of fifty millions of miles from the earth2 but if there was any danger in this meeting1 it was rather for it than for us2 for it was certainly strongly disturbed in its course4 ,it returned in #ahci1 but under conditions too unfavorable to enable it to be observed--in the month of ,july1 in the long days1 and too near the sun4 ,it was seen again in #ahde1 on ,november #beth1 near the place assigned to it by calculation1 and its course was duly followed4 ,everything went on to the general satisfaction1 when--unexpected spectacle6--on ,january #ac1 #ahdf1 the comet split into two6 ,what had passed in its bosom8 ,why this separation8 ,what was the cause of such a celestial cataclysm8 ,we do not know2 but the fact is1 that instead of one comet1 two were henceforth seen1 which continued to move in space like two twin-sisters--two veritable comets1 each having its nucleus1 its head1 its coma1 and its tail1 slowly separating from each other4 ,on ,february #ajth there was already a hundred and fifty thousand miles of space between the two4 ,they would seem1 however1 to have parted with regret1 and during several days a sort of bridge was seen thrown from one to the other4 ,the cometary couple1 departing from the earth1 soon disappeared in the infinite night4 ,they returned within view of the earth in the month of ,september1 #aheb4 ,on the #bfth of this month the twins reappeared1 but much farther apart1 separated by an interval of twelve hundred and fifty thousand miles4 ,but this is not the strangest peculiarity which this curious body presented to the attention of astronomers4 ,the catastrophe which was observed in #ahdf was only a presage of the fate which awaited it2 for now its existence is merely imagined1 the truth being that this comet is lost4 ,since #aheb all attempts to find it again have been unavailing4 ,to be lost is interesting1 especially for a comet4 ,but this1 doubtless1 was not enough2 for it reserved for us a still more complete surprise4 ,its orbit intersects the terrestrial orbit at a point which the earth passes on ,november #bgth4 ,well1 nothing more was thought about it--it was given up as hopeless1 when1 on the evening of ,november #bg1 #ahgb1 there fell from the sky a veritable rain of shooting stars4 ,the expression is not exaggerated4 ,they fell in great flakes4 ,lines of fire glided almost vertically in swarms and showers--here1 with dazzling globes of light2 there1 with silent explosions1 recalling to mind those of rockets2 and this rain lasted from seven o'clock in the evening till one o'clock next morning1 the maximum being attained about nine o'clock4 ,at the observatory of the ,roman ,college1 #ac1hib were counted2 at ,montcalieri1 #cc1djj2 in ,england a single observer counted #aj1egi1 etc4 ,the total number seen was estimated at a hundred and sixty thousand4 ,they all came from the same point of the sky1 situated near the beautiful star ,gamma of ,andromeda4 ,on that evening ,i happened to be at ,rome1 in the quarter of the ,villa ,medicis1 and was favored with a balcony looking towards the south4 ,this wonderful rain of stars fell almost before my eyes1 so to say1 and ,i shall never cease regretting not having seen it4 ,convalescent from a fever caught in the ,pontine ,marshes1 ,i was obliged to go into the house immediately after the setting of the sun1 which on that evening appeared from the top of the ,coliseum to sleep in a bed of purple and gold4 ,my readers will understand what disappointment ,i felt next morning when1 on going to the observatory1 ,father ,secchi informed me of that event6 ,how had he observed it himself8 ,by the most fortunate chance3 ,a friend of his1 seeing the stars fall1 went to him to ask an explanation of such a phenomenon4 ,it was then half-past seven4 ,the spectacle had commenced2 but it was far from being finished1 and the illustrious astronomer was enabled to view the marvelous shower of nearly fourteen thousand meteors4 ,this event made a considerable stir in ,rome1 and the pope himself did not remain indifferent2 for1 some days afterwards1 having had the honor of being received at the ,vatican1 the first words that ,pius ,,ix addressed to me were these3 8,have you seen the shower of ,dana80 ,i had admired1 some days before in ,rome1 some admirable 8,danas10 painted by the great masters of the ,italian school in a manner which left nothing to be desired2 but ,i had not had the privilege of finding myself under the cupola of the sky during this new celestial shower1 more beautiful even than that of ,jupiter4 ,what was this shower of stars8 ,evidently--and this is not doubtful--the encounter with the earth of myriads of small particles of matter moving in space along the orbit of ,biela's comet4 ,the comet itself1 if it still existed1 would have passed twelve weeks before4 ,it was not1 then1 to speak correctly1 the comet itself which we encountered1 but perhaps a fraction of its decomposed parts1 which1 since the breaking-up of the comet in #ahdf1 would be dispersed along its orbit behind the head of the comet4#a #a ,no doubt can remain of the identity of this swarm of shooting-stars with the comet of ,biela4 ,on ,november #bg1 #ahhe1 the same encounter occurred4 ,a magnificent shower of stars was observed all over ,europe just at the moment when the earth crossed the comet's orbit4 ,once in every thirty-three years we have a grand display of meteorites in ,november2 tens of thousands being visible in one single night4 ,the meteorites in that ring have their 8year0 of thirty-three earthly years1 and once in the course of that long year our earth's orbit carries her deep into their midst4 ,in this single ,november ring there are myriads upon myriads of meteorites1 spreading through millions of miles of space4 ,yet this system is but one among many4 ,there is no reason whatever to suppose that the streams of meteorites cluster more thickly about the orbit of the earth1 than in other parts of the ,solar ,system4 ,no doubt the rest of the planets come across quite as many4 ,indeed1 the wonderful rings of ,saturn are probably formed entirely of meteorites--millions upon millions of them whirling round the planet in a regular orbit-belt1 lit up by the rays of the sun4 ,also it is believed that the meteorite families cluster more and more closely in the near neighborhood of the sun1 rushing wildly round him1 and falling by millions into the ocean of flame upon his surface4 ,it has even been guessed that they may serve in part as fuel to keep up his mighty furnace heat4 ,there is a curious cone-shaped light seen sometimes in the west after sunset4 ,it is called the 8,zodiacal ,light10 and men have often been much puzzled to account for it4 ,the shining is soft and dim1 only to be seen when the sky is clear1 and only to be seen in the neighborhood of the sun4 ,this1 too1 may be caused by reflected light from countless myriads of meteorites gathering thickly round the sun4 ,,chapter ,,ix4 ,,neighboring ,,families4 ,we have now to take flight in thought far1 far beyond the outskirts of our little ,solar ,system4 ,yes1 our great ,solar ,system1 with its mighty sun1 its planets1 its moons1 its comets and meteorites1 its ceaseless motions1 its vast distances1--even all this sinks to littleness beside the wider reaches of space which now have to be pictured to our minds4 ,for our sun1 in all his greatness1 is only a single star--only one star among other stars--and not by any means one of the largest of the stars4 ,how many stars are there in the sky8 ,look overhead some cloudless night1 and try to count the brilliant points of light4 8,millions10 you would most likely give as your idea of their number4 ,yet you would be wrong2 for you do not really perceive so many4 ,the stars visible to man's naked eye have been mapped and numbered4 ,it is found that from two to three thousand are1 as a rule1 the utmost ever seen at once1 even on a favorable night1 and with particularly good sight4 ,but what is actually the full number of the stars8 ,two or three thousand overhead4 ,five or six thousand round the whole world4 ,so much visible to man's unaided eyes4 ,ah1 but take a telescope1 and see through it the opening fields of stars beyond stars4 ,take a stronger telescope1 and note how1 as you pierce deeper into space1 fresh stars beyond fresh stars shine faintly in the measureless distance4 ,take the most powerful telescope ever made1 and again it will be the same story4 ,there has been a chart or map drawn of known stars in the northern hemisphere--including those visible in telescopes down to a certain magnitude--containing over three hundred thousand4 ,but that is only a part of even what man can see4 ,sir ,william ,herschel calculated roughly that the number of stars within reach of his powerful telescope1 round the whole earth1 amounted probably to something like twenty millions4 ,twenty millions of suns6 ,for that is what it really means4 ,twenty millions of radiant1 burning1 heavenly bodies--some the same size as our sun2 some larger1 perhaps very much larger2 some smaller1 perhaps very much smaller2 but all ,,suns4 ,and any number of these suns may have1 just like our own1 families of planets traveling round them1 enjoying their light and their heat4 ,we talk about stars of the first1 second1 and other magnitudes4 ,stars can be seen without a telescope as low down as the sixth magnitude2 after that they become invisible to the naked eye4 ,this word 8magnitude0 is rather misleading4 8,magnitude0 means size1 and whatever the real size of the stars may be1 they have to our sight no seeming size at all4 ,so when we speak of different magnitudes1 we really mean different brightnesses4 ,the brightest stars are those of the first magnitude1 the next brightest those of the second magnitude1 and so on4 ,no doubt many a star of the third or fourth magnitude is really much larger than many a star of the first or second magnitude1 only being farther away it shines more dimly1 or the higher-magnitude star may in itself possess greater natural brilliancy4 ,of first-magnitude stars there are altogether about twenty2 of second-magnitude stars about sixty-five2 of third-magnitude stars about two hundred2 and so the numbers increase till of the sixth-magnitude stars we find more than three thousand4 ,these are all that can be commonly seen with the naked eye1 amounting to five or six thousand4 ,with telescopes the numbers rise rapidly to tens of thousands1 hundreds of thousands1 and even millions4 ,for a long while it was found quite impossible to measure the distances of the stars4 ,to this day the distances of not over two dozen1 among all those tens of thousands1 have been discovered4 ,the difficulty of finding out the distance of the sun was as nothing compared with the difficulty of finding out the distances of the stars4 ,no base-line sufficient for the purpose could for years be obtained4 ,i must explain slightly what is meant by a 8base-line40 ,suppose you were on the brink of a wide river1 which you had no means of crossing1 though you wished to discover its breadth4 ,suppose there were on the opposite brink a small tree1 standing alone4 ,as you stood1 you would see the tree seeming to lie against a certain part of the country beyond4 ,then1 if you moved along your bank some fifty paces1 the tree would seem to lie against quite a different part of the country beyond4 ,now if you had a long piece of string to lay down along the fifty paces you walked1 and if two more pieces of string were tied1 one from each end of the fifty paces1 both meeting at the tree1 then the three pieces of string would make one large triangle1 and the 8fifty paces0 would be the 8base0 of your triangle4 ,if you could not cross the river1 you could not of course tie strings to the tree4 ,but having found your base-line1 and measured its exact length1 and having also found the shape of the two angles at its two ends1 by noting the seeming change of the tree's position1 it would then be quite easy to find out the distance of the tree4 ,the exact manner in which this calculation is made can hardly be understood without some slight knowledge of a science called trigonometry4 ,the tree's distance being found1 the breadth of the river would be known4 ,this mode of measuring distance was found comparatively easy in the case of the moon4 ,but in the case of the sun there was more difficulty1 on account of the sun's greater distance4 ,no base-line of ordinary length would make the sun seem to change his position in the sky in the slightest degree4 ,nor till the very longest base-line on the earth was tried could the difficulty be overcome4 ,that base-line is no less than eight thousand miles long4 ,one man standing in ,england looking at the sun1 and another man standing in ,australia looking at the sun1 have such a base-line lying between them1 straight through the center of the earth4 ,in the case of the stars this plan was found useless4 ,so closely has the sky been mapped out1 and so exactly is the place of each star known1 that the tiniest change would have been at once noticed4 ,not a star showed the smallest movement4 ,the eight thousand miles of the earth's diameter was a mere point with regard to them4 ,a bright idea came up4 ,here was our earth traveling round the sun1 in an orbit so wide that in the middle of summer she is over one hundred and eighty millions of miles away from where she is in the middle of winter4 ,would not that make a magnificent base-line8 ,why not observe a star in summer and observe the same star again in winter1 and then calculate its distance4 ,this1 too1 was done4 ,for a long while in vain6 ,the stars showed no signs of change1 beyond those due to causes already known4 ,astronomers persevered1 however1 and with close and earnest care and improved instruments1 success at last rewarded their efforts4 ,a few--only a few1 but still a few--of those distant suns have submitted to the little measuring-line of earth1 and their distance has been roughly calculated4 ,now1 what is their distance8 ,alpha ,centauri1 the second star which was attempted with success1 is the nearest of all whose distance we know4 ,you have heard how far the sun is from the earth4 ,the distance of ,alpha ,centauri is two hundred and seventy-five thousand times as much4 ,can you picture to yourself that vast reach of space--a line ninety-three millions of miles long1 repeated over and over again two hundred and seventy-five thousand times8 ,but ,alpha ,centauri is one of the very nearest4 ,the brilliant ,sirius is at least twice as far away4 ,others utterly refuse to show the smallest change of position4 ,it is with them1 as had been said1 much the same as if a man were to look at a church-steeple1 twenty miles distant1 out of one pane in a window1 and then were to look at it out of the next pane4 ,with the utmost attention he would find no change of position in the steeple4 ,and like the base-line of two glass panes to that steeple1 so is the base-line formed by our whole yearly journey to thousands of distant stars4 ,we might measure how far away they are1 only the longest base-line within our reach is too short for our purpose4 ,the planet ,neptune has a wider orbit than ours4 ,but even his orbit1 seen from the greater number of the stars1 would shrink to a single point4 ,after all1 how useless to talk of two hundred and seventy-five thousand times ninety-three millions of miles6 ,what does it mean8 ,we can not grasp the thought4 ,let us look at the matter from another view4 ,do you know how fast light travels--this bright light shining round us all day long8 ,light1 so far as we know1 does not exist everywhere4 ,it travels to and fro1 from the sun to his planets1 from the planets to one another2 from the sun to the moon1 from the moon to the earth1 and from the earth to the moon again4 ,light takes time to travel4 ,this sounds singular1 but it is true4 ,light can not pass from place to place in no time4 ,light1 journeying through space1 is invisible4 ,only when it strikes upon something1 whether a solid body or water or air1 does it become visible to our eyes4 ,the shining all round us in the day-time is caused by the sunlight being reflected1 not only from the ground1 but from each separate particle of air4 ,if we had no atmosphere1 we should see still the bright rays falling on the ground1 but the sky above would be black4 ,yet that black sky would be full of millions of light-rays1 journeying hither and thither from sun and stars1 invisible except where they alight upon something4 ,the speed of light is far beyond that of an express train1 far beyond that of the swiftest planet4 ,in one tick of the clock1 ,mercury has rushed onward twenty-nine miles4 ,in one tick of the clock1 storm-flames upon the surface of the sun will sweep over two or three hundred miles4 ,but in one tick of the clock a ray of light flashes through one hundred and eighty-six thousand three hundred and thirty-seven miles4 ,one hundred and eighty-six thousand miles6 ,that is the same as to say that1 during one single instant1 a ray of light can journey a distance equal to about eight times round and round our whole earth at the ,equator4 ,by using this wonderful light-speed as a measurement1 we gain clearer ideas about the distances of the stars4 ,a ray of light takes more than eight minutes to pass from the sun to the earth4 ,look at your watch1 and note the exact time4 ,see the hand moving slowly through the minutes1 and imagine one single ray of light1 which has left the sun when first you looked1 flashing onward and onward through space1 one hundred and eighty-six thousand miles each second4 ,eight minutes and a half are over4 ,the ray falls upon your hand4 ,in those few minutes it has journeyed ninety-three millions of miles4 ,so much for the sun's distance4 ,how about the stars8 ,alpha ,centauri1 a bright star seen in the southern hemisphere1 is one of our nearest neighbors4 ,yet each light-gleam which reaches the eye of man from that star1 left ,alpha ,centauri four years and a third before4 ,during four years and a third1 from the moment when first it quitted the surface of the blazing sun1 it has flashed ceaselessly onward1 one hundred and eighty-six thousand miles each second1 dwindling down with its bright companion-rays from a glare of brilliancy to a slender glimmer of light till it reaches the eye of man4 ,four years and a third sounds much1 side by side with the eight minutes' journey from the sun4 ,sound would take more than three millions of years to cross the same abyss4 ,at the constant velocity of thirty-seven miles an hour1 an express-train starting from the sun ,alpha ,centauri would not reach the earth until after an uninterrupted course of nearly seventy-five millions of years4 ,this is our neighbor star4 ,the second1 the nearest after it1 is nearly double as far1 and is found in quite another region of space1 in the constellation of ,cygnus1 the ,swan1 always visible in our northern hemisphere4 ,if we wish to understand the relative situation of our sun and the nearest two1 let us take a celestial globe1 and draw a plane through the center of the globe and through ,alpha ,centauri and #fa ,cygni4 ,we shall thus have before us the relation which exists between our position in infinitude and those of these two suns4 ,the angular distance which separates them on the celestial sphere is #abe4 ,let us make this drawing1 and we shall discover certain rather curious particulars4 ,in the first place1 these two nearest stars are in the plane of the ,milky ,way1 so that we can also represent the ,milky ,way on our drawing2 again1 this celestial river is divided into two branches1 precisely in the positions occupied by these two nearest stars1 the division remaining marked along the whole interval which separates them4 ,this drawing shows us1 further1 that if we wish to trace the curve of the ,milky ,way with reference to the distance of our two stars1 it will be nearer to us in the constellation of the ,centaur than in that of the ,swan2 and1 in fact1 it is probable that the stars of that region of the sky are nearer than those of the opposite region4 ,another very curious fact is1 that both the nearest stars are double4 ,but look at ,sirius1 that beautiful star so familiar to us all4 ,the light which reaches you to-night1 left his surface from nine to ten years ago4 ,look at the ,little ,bear1 with the ,pole-star shining at the end of his tail4 ,that ray of soft light quitted the ,pole-star some forty years ago4 ,almost half a century it has been speeding onward and ever onward1 with ceaseless rapidity1 till its vast journey is so far accomplished that it has reached the earth4 ,look at ,capella1 another fair star of the first magnitude4 ,the light which reaches you from her has taken over thirty years to perform its voyage4 ,ten1 thirty1 forty years--at the rate of #ahf1jjj miles per second6 ,these stars are among the few whose distance can be roughly measured4 ,others lie at incalculable distances beyond4 ,there are stars whose light must1 it is believed1 have started hundreds or even thousands of years before the soft1 faint ray at length reaches the astronomer's upturned eye through the telescope4 ,look at ,capella1 how gently and steadily she shines6 ,you see ,capella1 not as she is now1 but as she was thirty years ago4 ,capella may have ceased to exist meantime4 ,the fires of that mighty sun may have gone out4 ,if so1 we shall by and by learn the fact--more than thirty years after it happened4 ,look at the ,pole-star4 ,is there any ,pole-star now8 ,i can not tell you4 ,i only know there was one1 forty years ago1 when that ray of light started on its long journey4 ,stars have ceased to shine before now4 ,what may have happened in those forty years1 who can say8 ,look at that dim star1 shining through a powerful telescope with faint and glimmering light4 ,we are told that in all probability the tiny ray left its home long before the time of ,adam4 ,there is a strange solemnity in the thought4 ,hundreds of years ago--thousands of years ago--some say1 even tens or hundreds of thousands of years ago6 ,it carries us out of the little present into the unknown ages of a past eternity4 ,if the neighboring stars are placed at tens and hundreds of trillions of miles from us1 it is at quadrillions1 at quintillions of miles that most of the stars lie which are visible in the sky in telescopic fields4 ,what suns6 what splendors6 ,their light comes from such distances6 ,and it is these distant suns which human pride would like to make revolve round our atom2 and it was for our eyes that ancient theology declared these lights1 invisible without a telescope1 were created6 ,no contemplation expands the thought1 elevates the mind1 and spreads the wings of the soul like that of the sidereal immensities illuminated by the suns of infinitude4 ,we are already learning that there is in the stellar world a diversity no less great than that which we noticed in the planetary world4 ,as in our own ,solar ,system the globes already studied range from #f miles in diameter 7satellites of ,mars7 up to #hh1jjj miles 7,jupiter7--that is to say1 in the proportion of #a to #ad1jjj--so in the sidereal system the suns present the most enormous differences of volume and brightness3 #fa ,cygni1 the stars numbered #b1cih in the catalogue of ,lalande1 and #i1ceb in the catalogue of ,lacaille1 and others of the eighth or ninth magnitude1 are incomparably smaller or less luminous than ,sirius1 ,arcturus1 ,capella1 ,canopus1 ,rigel1 and the other brilliants of the firmament4 ,,chapter ,x4 ,,our ,,neighbors' ,,movements4 ,how high6 how distant6 how mighty6 ,how little we know about them1 yet how overwhelming the little we know1 and how wonderful that we do know it6 ,we have now to consider the movements of these distant neighbors--first1 their seeming movements2 secondly1 their real movements4 ,i have already spoken about the seeming motions of the stars as a whole1 once believed to be real1 and now known to be only caused by the motions of our earth4 ,for just as the turning of the earth upon her axis makes the sun seem to rise every morning in the east1 and to set every evening in the west1 so that same continued turning makes the stars seem to rise every evening in the east and to set every morning in the west4 ,when we speak of the stars as rising in the east1 we do not mean that they all rise at one point in the east1 but that all rise1 more or less1 in an easterly direction--northeast1 east1 and southeast4 ,so also with respect to the west4 ,it is to the east and west of the earth as a whole that they rise and set--not merely to the east and west of that particular spot on earth where one man may be standing4 ,all night long fresh stars are rising1 and others are setting1 and if it were not for the veil of light made by the sunshine in our atmosphere1 we should see the same going on all day long as well4 ,there are some constellations1 or groups of stars1 always visible at night in our northern hemisphere2 and there are some constellations never visible to us1 but only seen by people living in the southern hemisphere--in ,australia1 for instance4 ,there are other constellations which appear in summer and disappear in winter1 or which appear in winter and disappear in summer4 ,this change is caused by our earth's journey round the sun4 ,it is not that the constellations have altered their place in the heavens with respect to the other constellations1 it is merely that the earth has so altered its position in the heavens that the groups of stars which a short time ago were above the horizon with the sun by day are now above the horizon without him by night4 ,mention has been a good many times made of the axis of the earth ending in the ,north and ,south ,poles4 ,if this axis were carried straight onward through space1 a long1 slender pole passing upwards into the sky without any bend1 from the ,north ,pole in one direction and from the ,south ,pole in the other1--this would be the pole of the heavens4 ,the places of the stars in the sky are counted as 8so many degrees0 from the ,north and ,south ,celestial ,poles1 just as the places of towns on earth are counted as 8so many degrees0 from the ,north and ,south ,poles of earth4 ,there are atlases of the sky made as well as atlases of the earth4 ,the constellation of the ,great ,bear is known to all who have ever used their eyes at all to watch the heavens4 ,almost equally well known are the two bright stars in this constellation named the ,pointers1 because1 taken together1 they point in nearly a straight line to a certain important star in the end of the ,little ,bear's tail1 not very distant4 ,this star1 important less from its brightness than from its position1 lies close to that very spot in the heavens where the celestial ,north ,pole passes4 ,it is called the ,pole-star4 ,night after night1 through the year1 it there remains1 all but motionless1 never going below the horizon for us in the northern hemisphere1 or northern half of the earth2 never rising above the horizon for those in the southern hemisphere4 ,it shines ever softly and steadily in its fixed position4 ,if you travel further south1 the ,pole-star sinks downward towards the horizon4 ,if you travel further north1 the ,pole-star rises higher above the horizon4 ,if you were at the ,north ,pole1 you would see the ,pole-star exactly overhead4 ,illustration3 ,,constellation ,,of ,,the ,,great ,,bear4 ,very near the ,pole-star is the constellation of the ,great ,bear1 with ,cassiopeia nearly opposite on the other side of the ,little ,bear1 and other groups between the two1 completing the circle4 ,these constellations do not1 to us who live in the northern hemisphere1 rise or set2 for they simply move in a circle round and round the ,pole-star1 never going below the horizon4 ,all day and all night long this circling movement continues1 though only visible at night4 ,it is caused entirely by the earth's own motion on her axis4 ,illustration3 ,,the ,,great ,,bear #ej1jjj ,,years ,,ago4 ,illustration3 ,,the ,,great ,,bear #ej1jjj ,,years ,,hence4 ,lower down1 or rather further off from the ,pole-star1 comes another ring of constellations4 ,these in just the same manner appear to travel round and round the ,pole-star4 ,but being further away1 each dips in turn below the horizon--or1 as we call it1 each sets and rises again4 ,and by the time we come to yet another circle of leading constellations1 we reach those which are so far affected by the earth's yearly journey as to be only visible through certain months1 and to be hidden during other months4 ,illustration3 ,,constellation ,,of ,,orion1 ,,as ,,it ,,appears ,,now4 ,if we could stand exactly at the ,north ,pole1 during part of its six months' night1 we should see the ,pole-star just overhead1 and all the constellations circling round it once in every twenty-four hours4 ,those nearest would move slowly1 in a small ring4 ,those furthest1 and lowest down1 would in the same length of time sweep round the whole horizon4 ,but the stars would not there seem to rise or set4 ,if we were standing at the ,south ,pole1 we should see exactly the same kind of seeming movement1 only with altogether a different set of stars4 ,if we were standing on the ,equator at night1 we should see the rising and setting very plainly4 ,the whole mass of stars would appear to rise regularly and evenly in an easterly direction1 to pass steadily across the sky1 each taking its own straightforward path1 and to set in a westerly direction4 ,we who are placed midway between the ,pole and the ,equator1 see a mixture of these two motions4 ,some stars seem to circle round and round1 as all would do if we stood at the ,north ,pole4 ,some stars seem to rise and set1 as all would do if we stood at the ,equator4 ,so much for the seeming movements of the stars4 ,but now1 about their real movements4 ,are the stars fixed1 or are they not8 ,these seeming daily and yearly motions do not affect the question1 being merely caused by our own motions4 ,trees and hedges may appear to move as we rush past them in a train1 yet they are really fixed4 ,illustration3 ,,constellation ,,of ,,orion #ej1jjj ,,years ,,from ,,now4 ,during a long while1 after it was found out that the quick1 daily movements of all the stars in company were merely apparent1 men believed that they really had no 8proper motions0--that is1 no movements of their own4 ,for century after century the constellations remain the same4 ,hundreds of years ago the seven chief stars of the ,great ,bear shone in company as they shine now4 ,who could suppose that each one of those seven stars is hurrying on its path through space with a speed exceeding far that of the swiftest express-train8 ,yet so it is4 ,hundreds of years ago the grand group of ,orion1 with belt and sword1 gleamed brilliantly night by night as it gleams in these days2 and ,cassiopeia had her ,w form1 and ,hercules and ,draco and ,andromeda were shaped as they are shaped still4 ,who would imagine that through those hundreds of years each star of these different constellations was hastening with more or less of speed along its heavenly road8 ,yet so it is4 ,cases have been decisively ascertained of stars changing their places among the other stars by a slow and gradual motion4 ,three of the most conspicuous of them--,sirius1 ,arcturus1 and ,aldebaran--have been proved1 by the comparison of modern with some ancient observations1 to have experienced a change of place to the southward1 to the extent of more than the breadth of the moon in all the three4 ,and during the period of accurate modern measurement1 other instances have been ascertained of steady change of place by the effect of proper motion4 ,but if the stars are thus rapidly moving in all directions1 how is it that we do not see them move8 ,how is it that1 night after night1 year after year1 century after century1 even thousand years after thousand years1 the shapes of the constellations remain unaltered8 ,suppose you and ,i were standing on the seashore together1 watching the movements of scores of sea-craft1 little boats and large boats1 steamers1 yachts1 and ships4 ,suppose we stood through a full quarter of an hour looking on4 ,some might move1 it is true1 very slowly2 yet their movements in every case would plainly be seen4 ,there could be no possibility of mistaking the fact1 or of supposing them to be 8fixed40 ,just so we see the nearer planets move4 ,little danger of our supposing them to be 8fixed stars40 ,in the matter of the stars themselves1 we must carry our illustration further4 ,come with me up to the top of that lofty hill on the border of the sea1 and let us look from the cliff4 ,we see still the movements among boats and smacks1 yachts and steamers1 only the increased distance makes the movements seem slower4 ,but our view is widened4 ,look on the far horizon and see three distant dots1 which we know to be ships--one and two close together1 and a third a little way off1 making a small constellation of vessels4 ,watch them steadily for a quarter of an hour4 ,you will detect no movement1 no increased distance or nearness between any two of the three4 ,the group remains unchanged4 ,are they really moving8 ,of course they are1 more or less rapidly1 probably with differing speed and in different directions4 ,but at so great a distance1 one quarter of an hour is not long enough for their motions to become visible to the naked eye4 ,if we could watch longer--say1 for two or three hours--ah1 that would make all the difference6 ,if only we could watch longer6 ,but the hundreds1 and even thousands of years during which men have watched the stars1 sink1 at our vast distance1 into no more than one quarter of an hour spent in watching the far-off ships from the high hilltop4 ,the motions can not be detected4 ,in ten thousand years you might see something4 ,in fifty thousand years you might see much4 ,but four or five thousand years are not sufficient4 ,one other mode there is1 by means of which the movements of the ships on the horizon might be made plain4 ,suppose you had no more than the quarter of an hour to spare1 but suppose you had at your command a powerful telescope4 ,then you may practically bring the ships nearer1 and by magnifying the small1 slow1 distant motions1 you may make them1 as it were1 larger1 quicker1 more easy to see4 ,telescopes will do this for us1 likewise1 in the matter of the stars4 ,by means of telescopes1 with the assistance of careful watching and of close calculation it has been found that the stars are really moving quickly1 each one in his own pathway4 ,the very speed of some of them has been measured4 ,arcturus is one of those stars1 the motions of which are most plainly to be seen4 ,in the course of about one thousand years he changes visibly his place in the sky by a space equal to the apparent diameter of the moon4 ,the seeming movement of ,arcturus in one thousand years is the same as the seeming width of the round moon that we see4 ,but the actual speed with which ,arcturus rushes through space is said to be no less than fifty-four miles each second1 or not far from two hundred thousand miles an hour4 ,that is nearly three times as fast as our own earth's motion round the sun4 ,how enormous the distance must be which can shrink such speed to such seeming slowness6 ,another beautiful star1 ,capella1 is believed to travel at the rate of thirty miles each second4 ,the speed of ,sirius is slower1 being only fourteen miles a second4 ,the ,pole-star creeps along at the rate of only one mile and a half each second4 ,so also with the rest of the stars4 ,there seems good reason to believe that every star we see shining in the heavens1 every star visible in powerful telescopes1 is perpetually hastening onward4 ,but hastening whither8 ,god knows6 ,we do not4 ,in all probability not one of the tens of millions of stars which may be seen through telescopes is in repose4 ,this is a matter of conjecture1 of reasoning from analogy1 and of reasoning also from the working of known laws4 ,we know1 as a consequence of direct observation1 apart from the new spectroscopic method1 that at least hundreds are upon the wing4 ,we assume1 as a matter of the greatest possible likelihood1 that all the millions besides1 which can not be actually seen to stir1 are equally on the move4 ,knowing what we do know of the laws by which the universe of stars is governed1 it seems to us an absolute impossibility that any single star1 amid the whole vast host1 can be or could be permanently at rest4 ,if by any means a star were brought to repose--what then would happen8 ,it would inevitably start off again1 drawn by the attraction of other stars4 ,from whatever direction the strongest pull came1 the impulse would be given4 ,lengthened repose would be out of the question4 ,and this1 it seems to us1 must be true1 not of one star only1 here or there1 but of every star in the enormous host of radiant suns which make up the mighty ,stellar ,system4 ,our forefathers1 one thousand years ago1 could not measure the precise positions of individual stars1 as astronomers now are able to do4 ,they had no modern observatories1 no telescopes1 no spectroscopes1 no photographic appliances4 ,these methods of observation we shall explain in another chapter4 ,their measurements at best were rough1 their scientific knowledge was crude4 ,had we any such accurate observations handed down from one thousand years ago as are made in these days1 we should no doubt see clearly many slight differences in the positions of many stars which are not now apparent4 ,but even then we should see no changes sufficient in amount to affect the general outlines of the leading constellations4 ,a star1 which in the course of a century makes visible advance over a space in the sky equal to only a small portion of the breadth of the full moon1 is looked upon as a fast voyager4 ,one hundred times this degree of movement1 if it took place in a considerable number of stars in our sky1 would not in centuries very materially change the face of our midnight heavens4 ,and all motions which would in the remotest degree affect the shapes of constellations1 must be sideway motions4 ,those line-of-sight motions1 of which the spectroscope alone tells us1 could never have been discovered by simple observation of the sky4 ,until the new method came to light we had no means whatever of perceiving such movements among the stars4 ,suppose you are looking at two men in the distance1 upon a wide1 flat plain4 ,one of the two is walking very slowly across your line of vision4 ,the second man is moving very slowly straight towards you4 ,if you watch with care you may find out both the movements4 ,the sideway walking will be apparent first and most easily1 because1 as the man moves1 he has constantly a fresh part of the horizon behind him4 ,but in time the advance of the second man towards you will also become apparent2 for although he is seen still against precisely the same spot on the horizon1 he slowly occupies a larger spot on the retina of your eye1--in other words1 he seems to grow bigger4 ,and that1 as you know from long experience1 can only mean increasing nearness4 ,if a star seemed to grow larger as it drew nearer1 we should then be able to perceive that movement also4 ,but no star in the sky ever does seem to grow any larger4 ,every star is to us but one point of light4 ,it may be rushing towards us at an enormous rate of speed1 yet still as a single point it remains1 always at the same point in our sky4 ,therefore we have no chance of perceiving its movement2 or rather1 we had no chance until the discovery of this new method4 ,in fact1 the very nearest known star is at so enormous a distance that1 supposing it to be coming towards us at the rate of one hundred miles each second1 it would still gain1 in the course of a century1 only one-fortieth part more of brightness than it has now4 ,it would not increase at all in apparent size4 ,when we leave behind us the thought of starry motions1 as we faintly detect them at this great distance1 and picture to ourselves the actual far-off whirl of all those glorious suns1 the effect upon the mind is overwhelming4 ,stars are found to be rushing hither and thither1 at every degree of speed1 in every imaginable direction3 stars to right1 and stars to left2 stars towards us1 and stars away from us2 stars alone1 and stars in company1--all this1 and more1 deciphered out of the tiny gleam of quivering light1 which streams through the vast abyss of space from each distant orb to earth4 ,so real star-motions were known--first1 through telescopic observation2 secondly1 through spectroscopic observation2 and now1 lastly1 photography has stepped in1 bringing with it much increase of exactitude4 ,but if all the stars are moving1 what of our sun8 ,our sun is a star4 ,and our sun also is moving4 ,he is pressing onward1 in a wide sweep through space1 bearing along with him his whole vast family--planets1 satellites1 comets1 meteorites--round or towards some far distant center4 ,for aught we know1 every star in the heavens may have a like family traveling with him4 ,in infinite space the stars are strewn in immense clusters1 like archipelagoes of islands in the ocean of the heavens4 ,to go from one star to another in the same archipelago light takes years2 to pass from one archipelago to another it takes thousands of years4 ,each of these stars is a sun similar to ours1 surrounded1 doubtless1 at least for the most part1 by worlds gravitating in its light2 each of these planets possesses1 sooner or later1 a natural history adapted to its constitution1 and serves for many ages as the abode of a multitude of living beings of different species4 ,attempt to count the number of stars which people the universe1 the number of living beings who are born and die in all these worlds1 the pleasures and pains1 the smiles and tears1 the virtues and vices6 ,imagination1 stop thy flight6 ,the sun is not one of the most quickly-moving stars4 ,his rate of speed has not been found out with any certainty1 but it is believed to be about four or five miles a second4 ,and where are we going8 ,this has been in part discovered4 ,if you and ,i were driving through a forest of trees1 we should see the trees on each side of us seeming to move backward1 while behind they would close together1 and in front they would open out4 ,astronomers--and first among them1 ,william ,herschel--reasoned that if our ,solar ,system were really in motion1 we ought to be able to see these changes among the stars4 ,and some such changes have become visible through careful watching--not so much those ahead and behind as those at the sides4 ,it is not actually so simple a matter as looking at the trees in a forest1 because the trees would be at rest1 whereas each star has his own particular real motion1 as well as his seeming change of place caused by our sun's motion4 ,it is more like moving in a small steamer at sea1 among hundreds of other craft1 each of which is going on its own way1 at the same time that all on either side seem to move backward because we are moving forward4 ,so each movement had to be noted1 and the real motions had to be separated from the seeming backward drift of stars to the right and left of the sun's pathway4 ,the result of all this is that the sun1 with his planets1 is found to be hastening towards a certain far-off constellation named ,hercules4 ,it is a strange and unexpected fact1 but absolutely true1 that each sun of space is carried along with a velocity so rapid that a cannon-ball represents rest in comparison2 it is at neither a hundred1 nor three hundred1 nor five hundred yards per second that the earth1 the sun1 ,sirius1 ,vega1 ,arcturus1 and all the systems of infinitude travel3 it is at ten1 twenty1 thirty1 a hundred thousand yards a second2 all run1 fly1 fall1 roll1 rush through the void--and still1 seen as a whole1 all seems in repose4 ,the immense distance which isolates us from all the stars reduces them to the state of motionless lights apparently fixed on the vault of the firmament4 ,all human eyes1 since humanity freed its wings from the animal chrysalis1 all minds since minds have been1 have contemplated these distant stars lost in the ethereal depths2 our ancestors of ,central ,asia1 the ,chaldeans of ,babylon1 the ,egyptians of the ,pyramids1 the ,argonauts of the ,golden ,fleece1 the ,hebrews sung by ,job1 the ,greeks sung by ,homer1 the ,romans sung by ,virgil1--all these earthly eyes1 for so long dull and closed1 have been fixed1 from age to age1 on these eyes of the sky1 always open1 animated1 and living4 ,terrestrial generations1 nations and their glories1 thrones and altars have vanished3 the sky of ,homer is always there4 ,is it astonishing that the heavens were contemplated1 loved1 venerated1 questioned1 and admired1 even before anything was known of their true beauties and their unfathomable grandeur8 ,better than the spectacle of the sea1 calm or agitated1 grander than the spectacle of mountains adorned with forests or crowned with perpetual snow1 the spectacle of the sky attracts us1 envelops us1 speaks to us of the ,infinite4 8,i have ascended into the heavens1 which receive most of ,his light1 and ,i have seen things which he who descends from on high knows not1 neither can repeat10 wrote ,dante in the first canto of his poem on 8,paradise40 ,let us1 like him1 rise towards the celestial heights1 no longer on the trembling wings of faith1 but on the stronger wings of science4 ,what the stars would teach us is incomparably more beautiful1 more marvelous1 and more splendid than anything we can dream of4 ,how do such contemplations enlarge and transfigure the vulgar idea which is generally entertained of the world6 ,should not the knowledge of these truths form the first basis of all instruction which aims at being serious8 ,is it not strange to see the immense majority of human beings living and dying without suspecting these grandeurs1 without thinking of learning something of the magnificent reality which surrounds them8 ,where the sun and his planets will journey in future ages no living man can say4 ,indeed1 though it is a question which does not lack interest to a thoughtful mind1 yet there are numberless other questions about centuries near at hand which concern man far more nearly4 ,the history of the ,universe1 and the history of this ,earth of ours1 must have advanced many broad stages before our sun and his attendant planets can have traveled so far that any change will be apparent in the shape of the star-constellations which spangle our sky4 ,,chapter ,,xi4 ,,more ,,about ,,the ,,solar ,,system4 ,we have now reached a point where it ought not to be difficult for us to picture to ourselves1 with something of vividness1 the general outlines of the ,solar ,system4 ,awhile ago this ,solar ,system was a very simple matter in the eyes of astronomers4 ,there was the great sun fixed in the center1 with seven planets circling round him--seven of course1 it was said1 since seven was the perfect number--and a few moons keeping pace with some of the planets1 and an occasional comet1 and a vast amount of black1 empty space4 ,but astronomers now begin to understand better the wonderful richness of the system as a whole2 the immense variety of the bodies contained in it2 the perpetual rush and stir and whirl of life in every part4 ,certainly there is no such thing as dull stagnation throughout the family4 ,first1 we have the great1 blazing1 central sun2 not a sun at rest1 as regards the stars1 but practically at rest as regards his own system1 of which he is always head and center4 ,then come the four smaller planets1 rapidly whirling round him1 all journeying in the same direction1 and all having their oval pathways lying on nearly the same flat plane in space4 ,then the broad belt of busy little planetoids4 ,then the four giant planets1--,jupiter nearly five times as far as our earth from the sun2 ,saturn nearly twice as far as ,jupiter2 ,uranus nearly twice as far as ,saturn2 ,neptune as far from ,uranus as ,uranus from ,saturn1--all keeping on very nearly the same level as the four inner planets4 ,illustration3 ,,position ,,of ,,planets ,,inferior ,,to ,,jupiter--,,showing ,,the ,,zone ,,of ,,the ,,asteroids4 ,and between and about these principal members of the system1 with their accompanying moons1 we have thousands of comets flashing hither and thither1 with long1 radiant trains2 and myriads of meteorites1 gathered often into dense1 vast herds or families1 but also scattered thickly throughout every part of the system1 each tiny ball reflecting the sun's rays with its little glimmer of light4 ,broad reaches of black and empty space6 ,where are they8 ,perhaps nowhere4 ,we are very apt1 in our ignorance1 to imagine that where we see nothing1 there must of necessity be nothing4 ,but1 for aught we know1 the whole ,solar ,system1 not to speak of sky-depths lying beyond1 may be bright with reflecting bodies great and small1 from the mighty ,jupiter down to the fine diamond-dust of countless meteorites4 ,in this earth of ours we find no emptiness4 ,closer and closer examination with the microscope only shows tinier and yet tinier wonders of form and life1 each perfect in finish4 ,not of form only1 but of life4 ,how about that matter as regards the ,solar ,system8 ,is our little world the one only spot in ,god's great universe which teems with life8 ,are all other worlds mere barren1 empty wastes8 ,surely not4 ,we may safely conclude that life of one kind or another has been1 is1 or will be1 upon our brother and sister worlds4 ,the same reasoning may be used for the distant stars--those millions of suns lying beyond reach of man's unassisted eyes4 ,are they formed in vain8 ,do their beams pour uselessly into space1 carrying light1 warmth1 and life-giving power to nothing8 ,surely around many of them1 as around our sun1 must journey worlds2 and not only worlds1 but worlds containing life4 ,we shall have to speak of this matter again as we go on4 ,whether men and women like ourselves could live on the other planets is another question4 ,in some cases it looks doubtful1 in some it would seem to be impossible4 ,but the endless variety of life on this earth--life on land1 life in the air1 life in water1 life underground1 life in tropical heat1 life in arctic cold--forbids us in anywise to be positive as to what may or may not be4 ,if no animals that we know could exist there1 animals that we do not know might be found instead4 ,any one of the planets may1 and very likely does1 abound with life4 ,nay1 the very meteorites themselves1 before they catch fire and burn in our air1 may be the homes of tiny animalcula1 altogether different from anything we see on earth4 ,we can not fancy life without air1 but neither could we fancy life in water1 if we had not seen and known it to be possible4 ,i have spoken of the probable brightness of the ,solar ,system as a whole4 ,we are so apt to think of things merely as we see them with our short sight1 that it is well sometimes to try to realize them as they actually are4 ,picture to yourself the great central sun pouring out in every direction his burning rays of light4 ,a goodly abundance of them fall on our earth1 yet the whole amount of light and heat received over the whole surface of this world is only the two-thousand-millionth part of the enormous amount which he lavishly pours into space4 ,how much of that whole is wasted8 ,none1 though ,god gives his gifts with a kingly profusion which knows no bounds4 ,each ray has its own work to do4 ,millions of rays are needed for the lighting and nourishing and warming of our companion-planets1 while others are caught up by passing comets1 and myriads flash upon swift1 tiny meteorites4 ,of the rays not so used1 many pass onwards into the vast depths beyond our system1 and dwindle down into dim1 starlike shining till they reach the far-off brother-stars of our sun4 ,have they work to do there8 ,we can not tell4 ,we do not know how far the sun's influence reaches4 ,as head and center1 he reigns only in his own system4 ,as a star among stars1 a peer among his equals1 he may1 for aught we can tell1 have other work to do4 ,in an early chapter1 mention was made of the earth's three motions1 two only being explained4 ,first1 she spins ceaselessly upon her axis4 ,so does the sun1 and so do the planets4 ,secondly1 she travels ceaselessly round and round the sun in her fixed orbit4 ,so does each one of the planets4 ,thirdly1 she journeys ceaselessly onward through space with the sun4 ,so also do the rest of the planets4 ,these last two movements1 thought of together1 make the earth's pathway rather perplexing at first sight4 ,we talk of her orbit being an ellipse or oval2 but how can it be an ellipse1 if she is always advancing in one direction8 ,the truth is1 the earth's orbit is and is not an ellipse4 ,as regards her yearly journey round the sun1 roughly speaking1 we may call it an ellipse4 ,as regards her movement in space1 it certainly is not an ellipse4 ,think of the ,solar ,system1 with the orbits of all the planets1 as lying nearly flat--in the manner that hoops might be laid upon a table1 one within another4 ,the asteroids1 comets1 and meteorites do not keep to the same level2 but their light weight makes the matter of small importance4 ,having imagined the sun thus in the center of a large table--a small ball1 with several tiny balls traveling round him on the table at different distances--suppose the sun to rise slowly upwards1 not directly up1 but in a sharp slant1 the whole body of planets continuing to travel round1 and at the same time rising steadily with him4 ,by carefully considering this double movement1 you will see that the real motion of the earth--as also of each of the planets--is not a going round on a flat surface to the same point from which she started1 but is a corkscrew-like winding round and round upwards through space4 ,yet as regards the central sun1 the shape of the orbit comes very near being an ellipse1 if calculated simply by the earth's distance from him at each point in turn of her pathway through the year4 ,an illustration may help to explain this4 ,on the deck of a moving vessel1 you see a little boy walking steadily round and round the mast4 ,now is that child moving in a circle1 or is he not8 ,yes1 he is4 ,no1 he is not4 ,he walks in a circle as regards the position of the mast1 which remains always the center of his pathway4 ,but his movement in space is never a circle1 since he constantly advances1 and does not once return to his starting-point4 ,you see how the two facts are possible side by side4 ,being carried forward by the ship1 with no effort of his own1 the forward motion does not interfere with the circling motion4 ,each is performed independently of the other4 ,it is the same with the earth and the planets4 ,the sun1 by force of his mighty attraction1 bears them along wherever he goes--no exertion on their part1 so to speak1 being needed4 ,that motion does not in the least interfere with their steady circling round the sun4 ,just as--to use another illustration--the earth1 turning on her axis1 bears through space a man standing on the ,equator at the rate of one thousand miles an hour4 ,but this uniform movement1 unfelt by himself1 does not prevent his walking backwards1 or forwards1 or in circles1 as much as he will4 ,so1 also1 a bird in the air is unconsciously borne along with the atmosphere1 yet his freedom to wheel in circles for any length of time is untouched4 ,a few words about the orbits of the planets4 ,i have more than once remarked that these pathways are1 in shape1 not circles1 but ellipses4 ,a circle is a line drawn in the shape of a ring1 every part of which is at exactly the same distance from the center-point or focus4 ,but an ellipse1 instead of being1 like a circle1 perfectly round1 is oval in shape2 and instead of having only one focus1 it has two foci1 neither being exactly in the center4 ,foci is the plural word for focus4 ,if an ellipse is only slightly oval--or slightly elliptical--the two foci are near together4 ,the more oval or eccentric the ellipse1 the farther apart are the two foci4 ,you may draw a circle in this manner4 ,lay a sheet of white paper on a board1 and fix a nail through the paper into the board4 ,then pass a loop of thread--say an inch or an inch and a half in length--round the nail1 and also round a pencil1 which you hold4 ,trace a line with the pencil1 keeping the loop tight1 so that the distance of your line from the nail will be always equal1 and when it joins you have a circle4 ,the nail in the center is the focus of the circle4 ,to draw an ellipse1 you must fix two nails4 ,let them be about half an inch apart2 pass a loop over both of them1 and again placing a pencil point within the loop1 again trace a line carefully all round1 keeping the thread drawn tight4 ,this time an oval instead of a circle will appear4 ,by putting the nails nearer together or farther apart1 you may vary as you will the shape of the ellipse4 ,in the orbits of the earth and the planets1 all of which are ellipses in shape1 the sun is not placed in the exact center1 but in one of the two foci1 the second being empty4 ,so at one time of the year the planet is nearer to the sun than at another time4 ,our earth is no less than three millions of miles nearer in winter than she is in summer--speaking of the winter and summer of the northern hemisphere4 ,three millions of miles is so tiny a piece out of ninety-three millions of miles1 that it makes little or no difference in our feelings of heat or cold4 ,the orbits of the comets are ellipses also1 but ellipses often so enormously lengthened out1 that the two foci are almost--if one may so speak--at the two ends of the oval4 ,to draw a good comet orbit1 you must fix the two nails on your paper some five or six inches apart1 with a loop of thread just large enough to slip over them both1 and to allow the pencil to pass round them4 ,when your ellipse is drawn1 you must picture the sun in the place of one of the two nails1 and you will see how1 in their pathways1 the comets at one time pass very near the sun1 and at another time travel very far away from him4 ,illustration3 ,,comparative ,,size ,,of ,,the ,,planetary ,,worlds4 ,it is generally found in families1 not only that the parent or head of the family has great influence over all the members1 but that each member has influence over each other member4 ,brother influences brother1 and sister influences sister4 ,this1 too1 we find in the ,solar ,system4 ,not only does the sun1 by his powerful attraction1 bind the whole family together1 but each member of the family attracts each other member4 ,true1 the force of the sun's attraction is overpowering in amount compared with others4 ,the sun attracts the planets1 and the planets attract the sun2 but their feeble pulling is quite lost in the display of his tremendous strength4 ,among themselves we see the power more plainly4 ,the earth attracts the moon1 keeping her in constant close attendance2 and the moon attracts the earth1 causing a slight movement on her part1 and also causing the tides of the sea4 ,each planet has more or less power to hinder or help forward his nearest brother-planet4 ,for instance1 when ,jupiter on his orbit draws near the slower ,saturn on his orbit1 ,saturn's attraction pulls him on1 and makes him move faster than usual2 but as soon as he gets ahead of ,saturn then the same attraction pulls him back1 and makes him go more slowly than usual4 ,jupiter has the same influence over ,saturn2 and so also have ,saturn and ,uranus over one another1 or ,uranus and ,neptune4 ,in early days astronomers were often greatly puzzled by these quickened and slackened movements1 which could not be explained4 ,now the 8perturbations0 of the planets1 as they are called1 are understood and allowed for in all calculations4 ,indeed1 it is by means of this very attraction that ,neptune was discovered1 and the planets have actually been weighed4 ,what a wonderful difference we find in this picture of the ,solar ,system1 as we now know it to be1 from the old-world notion of our earth as the center of the universe6 ,when we think of all the planets1 and of the magnificent sun2 when we pass onward in imagination through space1 and find our sun himself merely one twinkling star amid the myriads of twinkling stars scattered broadcast through the heavens1 while planets and comets have sunk to nothing in the far distance1--then indeed we begin to realize the unutterable might of ,god's power6 ,why1 our earth and all that it contains may be regarded as but one grain of dust in the wide universe4 ,,chapter ,,xii4 ,,more ,,about ,,the ,,sun4 ,not among the least of the wondrous things of creation are the tremendous disturbances taking place upon the surface of the sun--that raging1 roaring sea of flame4 ,a good many explanations have been from time to time offered as to the dark spots seen to move across the face of the sun4 ,some one or more of these explanations may be true2 but we know little about the matter4 ,a sun-spot does not commonly consist of merely one black patch4 ,there is the dark center1 called the umbra--plural1 umbr4 ,there is the grayish part surrounding the umbra1 called the penumbra4 ,also1 in the center of the umbra there is sometimes observable an intensely black spot1 called the nucleus4 ,sometimes a spot is made up of nucleus and umbra alone1 without any penumbra4 ,sometimes it is made of penumbra alone1 without any umbra4 ,sometimes in one spot there are several umbr1 with the gray penumbra round the whole1 and gray bridges dividing the umbr4 ,the enormous size of these spots has been already described in an earlier chapter4 ,fifty thousand to one hundred thousand miles across is nothing unusual4 ,in the year #ahci a spot was seen which measured no less than one hundred and eighty-six thousand miles in diameter4 ,one explanation proposed was1 that the sun might be a cool body1 covered over with different envelopes or dense layers of cloudy form1 one above another4 ,the inside envelope--or1 as some say1 the inside atmosphere--would then be thick and dull-colored1 protecting the solid globe within and reflecting light1 but having none of its own4 ,the next envelope would be one mass of raging1 burning gases--the photosphere1 in fact4 ,the outer envelope would be a transparent1 surrounding atmosphere1 lighted up by the sea of fire within4 ,a sun-spot would then consist of the tearing open of one or more of these envelopes1 so as to give glimpses of the gray1 inner atmosphere1 or even of the dark1 cool globe at the center4 ,there may be some truth in this explanation2 but the notion of a cool and dark body within is now pretty well given up4 ,the apparent blackness of a spot-nucleus does not prove actual blackness or absence of heat4 ,a piece of white-hot iron1 held up against the sun1 looks black2 and it may be merely the contrast of the glowing photosphere which makes the nucleus seem so dark4 ,it is even believed that the blackest parts may be the most intensely hot of all4 ,another proposed explanation was of dark clouds floating in the sun's atmosphere4 ,there1 again1 are found difficulties1 particularly in the fact that1 as the spots move across the sun1 the changes which regularly take place in their appearance make it pretty clear that their shape is not flat1 but hollow and cave-like4 ,the changes here spoken of are seeming changes of shape1 caused by change of position4 ,there are also real changes constantly taking place4 ,although the spots often keep their general outlines long enough to be watched across the face of the sun1 and even to be known again after spending nearly a fortnight hidden on the other side1 still they are far from being fixed in form4 ,illustration3 ,a ,,typical ,,sun-,,spot4 ,the alterations are at times not only very great1 but very rapid4 ,sometimes in a single hour of watching1 an astronomer can see marked movement going on--as you or ,i might in an hour observe movements slowly taking place in a high layer of clouds4 ,for movement to show at all in one hour1 at so immense a distance1 proves that the actual rate of motion must be very great4 ,the first great fact which was got from the study of these spots was this1 that this great sun is very much like our own earth1 in so far as it rotates on an axis in exactly the same way that our earth does4 ,not only do the spots change their position on the face of the sun1 in consequence of the sun's rotation on its axis1 but they change very much from day to day1 and even from hour to hour2 so that we have evidence not only that the sun is rotating like our earth1 but that the atmosphere of the sun is subjected to most tremendous storms--storms so tremendous1 in fact1 that the fiercest cyclones on our own earth are not for one moment to be compared with them4 ,the fact that the spots do really move with the sun1 and are really indentations1 saucer-like hollows1 in the photosphere1 is shown by the appearance1 which is always presented by a spot when it is near the edge of the sun4 ,you know if you take a dinner-plate1 and look it full in the face1 it is round2 but if you look at it edgeways1 it is not round4 ,take two different views of the same spot3 ,in one1 you look the sun-spot straight in the face1 and you see into it and can learn all about it2 but in the other1 when it has nearly gone round the corner1 and is disappearing on the sun's edge1 you see it in the same way that you would see a plate looked at edgeways4 ,these sun-cyclones must indeed be of terrific force and extent1 compared with anything we see on earth4 ,it was calculated that the speed of movement perceived in one spot was about three hundred and sixty-three miles each second4 ,and still all this is nothing1 or almost nothing1 in comparison with the real power of the sun6 ,the liquid state of the ocean2 the gaseous state of the atmosphere2 the currents of the sea2 the raising of the clouds1 the rains1 storms1 streams1 rivers2 the calorific value of all the forests of the globe and all the coal-mines of the earth2 the motion of all living beings2 the heat of all humanity2 the stored-up power in all human muscles1 in all the manufactories1 in all the guns1--all that is almost nothing compared with that of which the sun is capable4 ,do we think that we have measured the solar power by enumerating the effects which it produces on the earth8 ,error6 profound1 tremendous1 foolish error6 ,this would be to believe still that this star has been created on purpose to illuminate terrestrial humanity4 ,in reality1 what an infinitesimal fraction of the sun's total radiation the earth receives and utilizes6 ,in order to appreciate it1 let us consider the distance of ninety-three millions of miles which separates us from the central star1 and at this distance let us see what effect our little globe produces1 what heat it intercepts4 ,let us imagine an immense sphere traced at this distance from the sun1 and entirely surrounding it4 ,well1 on this gigantic sphere1 the spot intercepted by our little earth is only equivalent to the fraction #a_/b1ach1jjj1jjj2 that is to say1 that the dazzling solar hearth radiates all round it through immensity a quantity of light and heat two thousand one hundred and thirty-eight million times more than that which we receive1 and of which we have just now estimated the stupendous effects4 ,the earth only stops in its passage the two thousand millionth part of the total radiation4 ,sometimes the storms or outbursts come in the shape of a bright spot instead of a dark one4 ,illustration3 ,a ,,solar ,,eruption4 ,two astronomers were one day watching the sun from two different observatories1 when they saw such an event take place4 ,an intense and dazzling spot of light burst out upon the surface of the sun--so intense1 so dazzling1 as to stand quite apart from the radiant photosphere4 ,to one astronomer it looked like a single spot1 while the other saw two spots close together4 ,in about a minute the light grew more dim1 and in five minutes all was over4 ,but in those five minutes the spot or spots had traveled a distance of thirty-five thousand miles4 ,it was a very remarkable thing that the magnets on earth--those delicate little needles which point so steadily yet perseveringly towards the ,north ,pole--seemed to be strongly agitated by the distant solar outburst4 ,this brings us to another interesting fact4 ,the spots on the sun are not always the same in number4 ,sometimes they are many1 sometimes they are few4 ,long and close watching has made it clear that they pass through a regular order of changes3 some years of many spots being followed by other years of less and less spots2 then some years of very few spots being followed by other years of more and more spots1--decrease and increase being seemingly regular and alternate4 ,this turn or cycle of changes--from more to less1 and then from less to more again--is found to run its course about once in every eleven years1 with some variations4 ,now1 it has long been known that the magnetic-needle goes through curious variations4 ,though we speak of it as pointing always north1 yet it does not always so point exactly4 ,every day the needle is found to make certain tiny1 delicate motions1 as if faintly struggling to follow the daily movements of the sun--just a little towards the east1 or just a little towards the west4 ,these tiny motions1 having been long watched and measured1 were found to go through a regular course of changes--some years more1 and some years less1 waxing and waning by turns4 ,it was discovered that the course of changes from more to less1 and from less to more again1 took place in about eleven years4 ,these two things1 you see1 were quite independent of one another4 ,those who watched the sun-spots were not thinking of the magnets1 and those who watched the magnets were not thinking of the sun-spots4 ,but somebody did at last happen to think of both together4 ,he was laughed at1 yet he took the trouble carefully to compare the two4 ,and1 strange to say1 he found that these two periods in the main agreed--the eleven years of alternate changes in the number of sun-spots1 and the eleven years of alternate changes in the movements of the magnetic-needle4 ,when the spots are most1 the needle moves most4 ,when the spots are least1 the needle moves least4 ,so much we know4 ,but to explain the why and the wherefore is beyond our power4 ,this study of the magnetism of our wandering planet is very interesting1 and one which is still very little known4 ,here is a weak needle1 a slip of magnetic iron1 which1 with its restless and agitated finger1 incessantly seeks a region near the north4 ,carry this needle in a balloon up to the higher aerial regions1 where human life begins to be extinguished2 shut it up in a tomb closely separated from the light of day2 take it down into the pit of a mine1 to more than a thousand yards in depth1--and incessantly1 day and night1 without fatigue and without rest1 it watches1 trembles1 throbs1 seeks the point which attracts it across the sky1 through the earth1 and through the night4 ,now--and here is a coincidence truly filled with notes of interrogation--the years when the oscillation of this innocent little steel wire is strongest are the years when there are more spots1 more eruptions1 more tempests in the sun2 and the years when its daily fluctuations are weakest are those when we see in the day-star neither spots1 eruptions1 nor storms4 ,does there exist1 then1 a magnetic bond between the immense solar globe and our wandering abode8 ,is the sun magnetic8 ,but the magnetic currents disappear at the temperature of red-hot iron1 and the incandescent focus of light is at a temperature incomparably higher still4 ,is it an electrical influx which is transmitted from the sun to the earth across a space of ninety-three millions of miles8 ,on ,september #a1 #ahei1 two astronomers--,carrington and ,hodgson--were observing the sun1 independently of each other2 the first on a screen which received the image2 the second directly through a telescope1--when1 in a moment1 a dazzling flash blazed out in the midst of a group of spots4 ,this light sparkled for five minutes above the spots without modifying their form1 as if it were completely independent1 and yet it must have been the effect of a terrible conflagration occurring in the solar atmosphere4 ,each observer ascertained the fact separately1 and was for an instant dazzled4 ,now1 here is a surprising coincidence3 at the very moment when the sun appeared inflamed in this region the magnetic instruments of the ,kew ,observatory1 near ,london1 where they were observing1 manifested a strange agitation2 the magnetic needle jumped for more than an hour as if infatuated4 ,moreover1 a part of the world was on that day and the following one enveloped in the fires of an aurora borealis1 in ,europe as well as in ,america4 ,it was seen almost everywhere1--at ,rome1 at ,calcutta1 in ,cuba1 in ,australia1 and in ,south ,america4 ,violent magnetic perturbations were manifested1 and at several points the telegraph-lines ceased to act4 ,why should these two curious events not be associated with each other8 ,a similar coincidence was observed on ,august #c1 #ahgb1 by ,professor ,charles ,a4 ,young1 of ,princeton1 ,n4 ,j43 a paroxysm in the solar chromosphere1 magnetic disturbances everywhere4 ,there is a very singular appearance seen upon the sun which must not be passed over without mention4 ,some astronomers speak of the whole surface as being mottled all over with a curious rough look when examined through a powerful telescope4 ,this 8mottling0 is described by various observers in various ways4 ,one speaks of 8luminous spots shaped like rice-grains40 ,another1 of 8luminous spots resembling strokes made with a camel's-hair pencil40 ,another1 of 8luminous objects or granules40 ,others1 of 8multitudes of leaves10 8nodules10 8crystalline shapes10 8leaves or scales1 crossing one another in all directions1 like what are called spills in the game of spillikens40 ,they have also been pictured as 8certain luminous objects of an exceedingly definite shape and general uniformity of size1 whose form is that of the oblong leaves of a willow-tree40 ,these cover the whole disk of the sun1 excepting the space occupied by the spots1 in countless millions1 and lie crossing each other in every imaginable direction4 ,in size they are said to be about one thousand miles long1 by two or three hundred broad1 but they vary a good deal4 ,where there is a spot1 the willow-leaves at its edge are said to point pretty regularly towards the center4 ,whether they are1 as they seem to be1 solid in form2 whether they are1 as some suppose1 the chief source of the sun's light and heat2 whether they lie on his surface or float in his atmosphere2 what is their real nature1 and what is their real use1--about these questions we are at present quite in the dark4 ,we have next to think a little more about the edge or limb of the sun1 and the stormy flames and outburst there seen4 ,until quite lately the only time for observing such appearances was during a total eclipse of the sun4 ,lately1 by means of the new instrument called the 8spectroscope10 it has been found possible to take observations when no eclipse is going on4 ,illustration3 ,,sun-,,flames1 ,,may #c1 #ahib4 ,a few words of explanation as to eclipses of the sun seem needful1 before going further4 ,an eclipse of the sun is caused simply by the round body of the moon passing exactly between the sun and the earth1 so as to hide the sun from us4 ,let there be a candle on the table1 while you stand near4 ,the rays of light from the candle fall upon your face4 ,now move slowly1 to and fro1 a round ball between you and the candle4 ,so long as it is not precisely in the line between--so long as it is a little higher1 or a little lower1 or a little to one side--then you can still see the flame4 ,once you let the ball come just between the light and your eyes1 and you see it no more4 ,in other words the candle-flame is eclipsed--hidden1 veiled1 cut off--by the ball4 ,it may seem curious at first sight that the moon1 which is very small compared with the sun1 should have power to cover the sun4 ,but remember the difference of the distance4 ,the sun is very far1 and the moon is very near4 ,any small object very near will easily hide from your sight a large object at a considerable distance4 ,you may hold up a shilling-piece at arm's length1 and make it cover from sight a man1 or even a house1 if the latter be far enough away4 ,the sun at a distance of ninety-three millions of miles1 and the moon at a distance of two hundred and forty thousand miles1 have to our vision the same seeming size4 ,so1 when the moon glides between1 her round face just about covers the sun's round face4 ,if the moon were traveling exactly in the same plane as the plane of the earth's orbit1 an eclipse would be a very common affair indeed4 ,but the plane of the moon's orbit being not quite the same as the plane of the earth's orbit1 she passes sometimes a little above1 and sometimes a little below1 the exact spot where she would hide the sun's rays from us4 ,now and then1 at certain intervals1 she goes just between4 ,and so well is the moon's path in the heavens understood that astronomers can tell us1 long years beforehand1 the day and the hour an eclipse will take place4 ,an eclipse of the sun is sometimes partial1 sometimes total1 sometimes annular4 ,in a partial eclipse1 the moon does indeed pass between1 but only so as to hide from us part of the sun4 ,she is a little too low1 or a little too high1 to cover his face4 ,in a total eclipse1 the moon covers the sun completely1 so that for a few minutes the bright photosphere seems blotted out from the heavens1 a black round body1 surrounded by light1 taking its place4 ,in an annular eclipse1 the moon in like manner crosses the sun1 but does not succeed in covering him entirely1 a rim of bright photosphere showing round the black moon4 ,for in an annular eclipse1 the moon1 being a little farther away from the earth than at the time of a total eclipse1 has too small a disk quite to hide the sun's disk4 ,the blackness of the moon during an eclipse is caused by the fact that her bright side is turned towards the sun1 and her dark side toward us4 ,an eclipse of the sun can take place only at new moon1 never at full moon4 ,at her full1 the moon is outside the earth's orbit1 away from the sun1 and can not by any possibility pass between4 ,eclipses1 like comets1 have always been interpreted as the indication of inevitable calamities4 ,human vanity sees the finger of ,god making signs to us on the least pretext1 as if we were the end and aim of universal creation4 ,let us mention1 for example1 what passed even in ,france1 with reference to the announcement of an eclipse of the sun1 on ,august #ba1 #aefj4 ,for one1 it presaged a great overthrow of ,states and the ruin of ,rome2 for another1 it implied another universal deluge2 for a third1 nothing less would result than a conflagration of the globe2 finally1 for the less excited1 it would infect the air4 ,the belief in these terrible effects was so general that1 by the express order of the doctors1 a multitude of frightened people shut themselves up in very close cellars1 well heated and perfumed1 in order to shelter themselves from these evil influences4 ,petit relates that the decisive moment approached1 that the consternation was at its height1 and that a parish priest of the country1 being no longer able to confess his parishioners1 who believed their last hour had come1 was obliged to tell them in a sermon 8not to be so much hurried1 seeing that1 on account of the wealth of the penitents1 the eclipse had been postponed for a fortnight40 ,these good parishioners found no more difficulty in believing in the postponement of the eclipse than they had in believing in its unlucky influence4 ,history relates a crowd of memorable acts on which eclipses have had the greatest influence4 ,alexander1 before the battle of ,arbela1 expected to see his army routed by the appearance of a phenomenon of this kind4 ,the death of the ,athenian general ,nicias and the ruin of his army in ,sicily1 with which the decline of the ,athenians commenced1 had for their cause an eclipse of the moon4 ,we know how ,christopher ,columbus1 with his little army1 threatened with death by famine at ,jamaica1 found means of procuring provisions from the natives by depriving them in the evening of the light of the moon4 ,the eclipse had scarcely commenced when they supplied him with food4 ,this was the eclipse of ,march #a1 #aejd4 ,we need not relate other facts of this nature1 in which history abounds1 and which are known to every one4 ,eclipses no longer cause terror to any one1 since we know that they are a natural and inevitable consequence of the combined motions of the three great celestial bodies--the sun1 the earth1 and the moon2 especially since we know that these motions are regular and permanent1 and that we can predict1 by means of calculation1 the eclipses which will be produced in the future as well as recognize those which have occurred in the past4 ,the following description of the total eclipse of #ahfj will be found interesting4 ,mr4 ,lowe1 who observed it at ,santander1 ,spain1 thus writes3 8,before totality commenced1 the colors in the sky and on the hills were magnificent beyond all description4 ,the clear sky in the north assumed a deep indigo color1 while in the west the horizon was first black like night4 ,in the east the clear sky was very pale blue1 with orange and red1 like sunrise4 ,on the shadow creeping across1 the deep blue in the north changed1 like magic1 to pale1 sunrise tints of orange and red1 while the sunrise appearance in the east had changed to indigo4 ,the darkness was great2 the countenances of men were of a livid pink4 ,the ,spaniards lay down1 and their children screamed with fear2 fowls hastened to roost1 ducks clustered together1 pigeons dashed against the houses2 flowers closed2 many butterflies flew as if drunk1 and at last disappeared4 ,the air became very humid1 so much so that the grass felt to one of the observers as if recently rained upon40 ,,chapter ,,xiii4 ,,yet ,,more ,,about ,,the ,,sun4 ,having seen something of storms taking place on the sun's photosphere1 we must next give our attention to storms taking place at his edge4 ,but it should be remembered that the said edge1 far from being a mere rim to a flat surface1 is a kind of horizon-line--is1 in fact1 just that part of the photosphere which is passing out of or coming under our sight4 ,the surface there is1 in kind1 the same as the surface of the broad disk facing us4 ,in watching outbursts at the edge of the sun1 we have a side view instead of a bird's-eye view4 ,in the year #ahga1 ,professor ,charles ,a4 ,young1 of ,princeton1 was looking at a large hydrogen cloud on the edge of the sun4 ,when ,i speak of a 8cloud10 it must not be supposed that anything like a damp1 foggy1 earthly cloud is meant4 ,this solar cloud was a huge mass of red-hot gas1 about one hundred thousand miles long1 rising to a height of fifty thousand miles from the sun's surface1 and appearing to rest on glowing pillars of fire4 ,the professor1 while watching1 was called away for half an hour4 ,he came back1 expecting to find things much as he had left them4 ,instead of this1 a startling change had taken place4 ,the whole mass of glowing fire seemed to have been actually 8blown to shreds0 by some tremendous outburst from below4 ,in place of the motionless cloud were masses of scattered fire1 each from about four thousand to fourteen thousand miles long1 and a thousand miles wide4 ,as the professor gazed1 these 8bits0 of broken cloud rose rapidly upwards1 away from the surface of the sun4 ,when ,i say 8rapidly10 ,i mean that the real movement1 which the professor could calculate1 was rapid4 ,the seeming movements were of course slow1 and over a small space4 ,the actual motions were not tardy1 for in ten minutes these huge1 fiery cloud-pieces rushed upwards to a height of two hundred thousand miles from the edge of the sun1 moving at a rate of at least one hundred and sixty-seven miles each second4 ,gradually they faded away4 ,but what caused this sudden change8 ,just before the professor was interrupted1 he had noticed a curious little brilliant lump--a sort of suspicious thunder-cloud appearance--below the quiet1 bright cloud4 ,and after this tremendous shattering1 the little bright lump rose upwards into a huge mass of rolling flame1 reaching like a pyramid to a height of fifty thousand miles4 ,in the course of a few minutes these enormous flames could be seen to move and bend1 and to curl over their gigantic tips4 ,but they did not last long4 ,at half-past twelve the professor had been called away2 by half-past two the rolling flames completely vanished4 ,now1 whatever may be the full explanation of this sight1 there is no doubt that on that day was observed from earth a tremendous outburst1 compared with which our mightiest volcanoes are like the sputtering of a farthing dip beside a roaring furnace4 ,the awful force and greatness of such a solar eruption are more than we can possibly picture to ourselves4 ,at our distance we may catch a faint glimpse of what is going on1 and calculate speed of movement4 ,but vividly to realize the actual terrific grandeur of what took place is past our power4 ,possibly this was much the same kind of outburst as that seen by the two ,english astronomers2 only theirs was a bird's-eye view1 as it were1 looking down on the top of the sight1 while the professor had a side-view1 certainly much the best for observation4 ,it does not follow from what he saw that the eruption must have taken place exactly at the 8edge0 of the sun4 ,probably it happened near the edge4 ,all he could say1 was that the flames rose fifty thousand miles1 and the pieces of cloud were carried two hundred thousand miles1 away from the edge4 ,the eruption may have begun on the other side of the sun1 at any distance from the horizon-edge where it first became visible to earthly eyes4 ,also1 while the professor found that the shattered cloudlets moved at a rate of about one hundred and sixty-seven miles each second1 it is calculated that the first fearful outburst must have caused movement1 near the surface of the sun1 at a rate of at least three hundred miles each second4 ,probably the hydrogen cloud was borne upwards along with a vast mass of fragments flung out from the sun4 ,we are here upon doubtful ground2 but this tremendous power of eruption in the sun1 and of driving matter out of and away from his surface1 should not be forgotten4 ,though such a sun-storm as that just described is not often to be seen1 yet there are at all times certain strange red prominences1 or glowing flames1 rising up here and there from the sun's 8limb40 ,doubtless they rise also from other parts of the photosphere1 though they are only visible to us when near enough to the edge to stand out beyond it4 ,seen during an eclipse1 these prominences have clear1 sharp outlines1 and are usually bright rose-red in color4 ,they are described as sometimes wide and low1 sometimes tall and slender2 sometimes jagged1 sometimes regular2 sometimes keeping long the same shape1 sometimes changing quickly in a few minutes4 ,they are said to be like flames1 like mountains1 like the teeth of a saw1 like icebergs1 like floating cloudlets4 ,as to their height1 from fifty to eighty thousand miles is nothing unusual4 ,we must not speak of ,mont ,blanc or ,mount ,everest here4 ,jupiter placed bodily on the surface of the sun1 beside such a fire-mountain1 would not far overtop it4 ,the earth1 ,venus1 ,mars1 and ,mercury1 would lie like little toy-balls at its foot4 ,and these are common-sized sun-flames4 ,one was measured which reached to the enormous height of two hundred thousand miles4 ,the spectroscope shows these solar prominences or jets to be made--at least in part--of burning hydrogen gas4 ,beyond the sierra or chromatosphere--that border of rippling1 crimson flame-billows round the edge of the sun1 with red flame-mountains rising out of it here and there--beyond these1 stretches the corona4 ,the corona1 as seen from earth1 is a bright1 far-reaching glory of light1 shining round the sun in a total eclipse4 ,the moon then comes between the sun and the earth1 her dark1 round body creeping over the face of the sun till the bright photosphere is completely covered4 ,but the sierra and the tall1 red flames stand out from behind the black moon1 and the beautiful1 soft corona-light stretches far beyond4 ,illustration3 ,,solar ,,corona ,,and ,,prominence4 ,it was long doubted whether the corona really belonged to the sun or to the moon4 ,there seems now no doubt that it is a part of the sun4 ,various descriptions of the corona have been given at different times1 as observed during different eclipses4 ,it has been seen as a steady1 beamy1 white cloud behind the moon1 showing no flickering4 ,it has been seen marked with bright lines of light1 and seeming to move rapidly round and round4 ,it has been seen silvery white1 sending off long streams of brightness4 ,it has been seen in the form of white light1 with bluish rays running over it4 ,it has been seen with entangled jets of light1 like 8a hank of thread in disorder40 ,it has been seen silvery-white again1 with a faint tinge of greenish-violet about the outer edge4 ,it has been seen from a high mountain-top as a mass of soft1 bright light1 8through which shot out1 as if from the circumference of the moon1 straight1 massive1 silvery rays1 seeming distinct and separate from each other1 to a distance of two or three diameters of the lunar disk1 the whole spectacle showing as upon a background of diffused1 rose-colored light40 ,majestic1 indeed1 are the proportions of some of those mighty flames which leap from the surface of the sun1 yet these flames flicker1 as do our terrestrial flames1 when we allow them time comparable to their gigantic dimensions4 ,drawings of the same prominence often show great changes in a few hours1 or even less4 ,the magnitude of the changes could not be less than many thousands of miles1 and the actual velocity with which such masses move is often not less than one hundred miles a second4 ,still more violent are the solar convulsions1 which some observers have been so fortunate as to behold1 when from the sun's surface1 as from a mighty furnace1 vast incandescent masses are projected upwards4 ,all indications point to the surface of the sun as the seat of the most frightful storms and tempests1 in which the winds sweep along incandescent vapors4 ,the corona consists of two parts--the inner and brighter corona1 the outer and fainter corona4 ,the shape of the whole seems to change much at different times4 ,the outer edge is usually blurred and indistinct1 fading gently away4 ,many explanations have been suggested4 ,at one time the corona was supposed to be a solar atmosphere1 reflecting light like our own atmosphere4 ,some have thought the light might be caused by countless myriads of meteorite systems1 revolving in the close neighborhood of the sun4 ,some suppose it may be owing1 in part at least1 to solar eruptions1 and the pouring outward of burning gas and matter4 ,but our knowledge of the true nature of the corona is yet in its infancy4 ,a few closing words as to the size and weight of the sun4 ,in diameter1 eight hundred and fifty-eight thousand miles1 and in bulk equal to one million two hundred and eighty thousand earths1 his weight is in proportion less4 ,our earth is about four times as dense as the sun4 ,if her size were increased to the sun's size1 her density being the same as now1 she would be very much heavier than the sun1 and would attract much more strongly4 ,still1 though the sun is of lighter materials than the earth1 his immense size gives him weight equal to seven hundred and fifty times as much as all the planets put together4 ,the attraction on the surface of the sun is also very great--so great that we can hardly picture it to ourselves4 ,if life exists there at all--supposing it possible that any kind of life can be in such a fiery atmosphere--it must be life very different from any known in this world4 ,a man who on earth weighs one hundred and sixty pounds1 and walks lightly erect1 would1 on the sun1 lie helplessly bound to the ground1 crushed by his own overpowering weight4 ,it is said that a cannon-ball1 reposing on the sun1 if lifted one inch and allowed to fall1 would dash against the ground with a speed three times greater than that of our fastest express-trains4 ,for weight on earth is merely caused by the amount of force with which the earth draws downward a body towards herself--a force greater or less according to the density of that body4 ,so weight on the sun would be immensely increased by his immensely greater power of attraction4 ,illustration3 ,,comparative ,,size ,,of ,,the ,,earth ,,and ,,sun4 ,it is an interesting question how far the sun's attractive influence reaches effectually through space4 ,the nearer a body is to the sun1 the greater the attraction which he exercises over it4 ,at the distance of the planet ,mercury1 a speed of twenty-nine miles each second is needful to overcome or balance it sufficiently for the planet to remain in his orbit4 ,at the distance of the planet ,neptune1 about three miles each second is enough4 ,if a planet were journeying at four times the distance of ,neptune1 the speed would need to be not over two miles each second1 lest the planet should break loose and wander away4 ,but even two miles a second is no mean speed--more than seven thousand miles an hour4 ,if we come to speak of that which we on earth call rapid motion1 we shall gain a clearer idea as to the extent of the sun's power4 ,suppose a planet were traveling through space at the rate of one of our fastest express-trains--sixty miles an hour4 ,it has been calculated that1 unless the sun's attraction were interfered with and overpowered by some nearer sun1 the said planet1 though placed at a distance ten or twelve times as great as that of the far-off star ,alpha ,centauri1 would still be forced by the sun's attraction to journey round him in a closed orbit4 ,at such a speed it would not be free to wander off into the depths of space4 ,,chapter ,,xiv4 ,,more ,,about ,,the ,,moon4 ,from a globe all fire1 all energy1 all action1 we come to a globe silent1 voiceless1 changeless1 lifeless4 ,so1 at least1 the moon seems to us4 ,but it will not do to speak too confidently4 ,true1 we can find no trace of an atmosphere in the moon4 ,if there is any atmosphere at all1 it must be so thin as to be less than that which we on earth count as actually none4 ,we pump away the air from a glass inclosure in an air-pump1 and say the glass is empty4 ,only it is not quite empty4 ,there is always just a very little air remaining1 though so little that fire would not burn and animals could not live in it4 ,some believe that air1 up to that amount1 may be found in the moon4 ,but this is much the same as to say there is none at all4 ,for1 of course1 with either no air or so very little air1 life can not possibly exist on the moon4 ,we can not imagine such a thing for a moment4 ,that is just how the matter stands4 ,we 8can not imagine10 and therefore we conclude it to be an impossibility4 ,as if we knew a hundredth part of the possibilities in any one corner of ,god's great universe6 ,as if our being unable to picture a thing proves that thing not to exist6 ,suppose we had always lived in tropical heat1 and had never seen1 known1 or heard of such a fact as life in ,arctic snows4 ,should we consider it a thing possible8 ,suppose we had always lived on dry land1 with never a sight of sea or river or pond1 and never a proof that animal life could exist under water--aye1 and that some living animals may be suffocated by air1 just as other living animals are suffocated by water4 ,should we not1 in our wisdom1 reason out such a state of affairs to be utterly impossible8 ,there may be no life on the moon4 ,it may be that she is now passing through a dead1 cold1 blasted stage1 either at the close of some past history1 or in preparation for some future history--or both4 ,but1 on the other hand1 it may be that the moon is no less full of life than the earth2 only the life must be different in kind1 must be something which we do not know any thing at all about4 ,the moon is very much smaller than the earth4 ,her diameter is about two-sevenths of the earth's diameter2 her entire surface is about two twenty-sevenths of the earth's surface2 her size is about two ninety-ninths of the earth's size2 and her whole weight is about one-eightieth of the earth's weight4 ,attraction or gravitation on the surface of the moon is very different from what it is on the earth4 ,her much smaller bulk greatly lessens her power of attraction4 ,while a man from earth would1 on the surface of the sun--supposing he could exist there at all--lie helpless1 motionless1 and crushed by his own weight1 he would on the moon find himself astonishingly light and active4 ,a leap over a tall house would be nothing to him4 ,illustration3 ,,the ,,moon--,,an ,,expired ,,planet4 ,the moon1 unlike the sun1 has no light or heat of her own to give out4 ,she shines merely by reflected light4 ,rays of sunlight falling upon her1 rebound thence1 and find their way earthward4 ,this giving of reflected light is not a matter all on one side4 ,we yield to the moon a great deal more than she yields to us4 ,full earth1 seen from the moon1 covers a space thirteen times as large as full moon seen from earth4 ,perhaps you may have noticed1 soon after new moon1 when a delicate crescent of silver light shows in the sky1 that within the said crescent seems to lie the body of a round1 dark moon1 only not perfectly dark4 ,it shows a faint glimmer4 ,that glimmer is called earth-shine4 ,the bright crescent shines with reflected sunlight4 ,the dim portion shines with reflected earth-light4 ,what a journey those rays have had6 ,first1 leaving the sun1 flashing through ninety-three millions of miles to earth1 rebounding from earth and flashing over two hundred and forty thousand miles to the dark shaded part of the moon1 then once more rebounding and coming back1 much wasted and enfeebled1 across the same two hundred and forty thousand miles1 to shine dimly in your eyes and mine4 ,the popular description of this particular view of the moon is 8the old moon in the arms of the new40 ,now about the phases of the moon2 that is1 her changes from 8new0 to 8full10 and back again to 8new40 ,if the moon were a starlike body1 shining by her own light1 she would always appear to be round4 ,but as she shines by reflected sunlight1 and as part of her bright side is often turned away from us1 the size and shape of the bright part seem to vary4 ,for1 of course1 only that half of the moon which is turned directly towards the sun is bright4 ,the other half turned away is dark1 and can give out no light at all1 unless it has a little earth-shine to reflect4 ,as the moon travels round the earth1 she changes gradually from new to full moon1 and then back to new again4 8,new moon0 is when the moon1 in her orbit1 comes between the sun and the earth4 ,the half of her upon which the sun shines is turned away from us1 and only her dark side is towards us4 ,so at new moon she is quite invisible4 ,it is at new moon that an eclipse of the sun takes place1 when the moon's orbit carries her in a line precisely between sun and earth4 ,passing onwards round the earth1 the moon1 as we get a little glimpse of her shining side1 first shows a slender sickle of light1 which widens more and more till she reaches her first quarter4 ,she is then neither between earth and sun1 nor outside the earth away from the sun1 but just at one side of us1 passing over the earth's own orbit4 ,still1 as before1 half her body is lighted up by the sun4 ,by this time half the bright part and half the dark part are turned towards us2 so that1 seeing the bright quarter1 we name it the 8first quarter40 ,on and on round us moves the moon1 showing more light at every step4 ,now she passes quite outside the earth's orbit1 away from the sun4 ,not the slightest chance here of an eclipse of the sun1 though an eclipse of the moon herself is quite possible4 ,but more of that presently4 ,as she reaches a point in a line with earth and sun--only generally a little higher or lower than the plane of the earth's orbit--her round1 bright face1 shining in the sun's rays1 is turned exactly towards us4 ,then we have 8full moon40 ,still she goes on4 ,once more her light narrows and wanes1 as part of her bright half turns away4 ,again at the 8last quarter10 as at the first1 she occupies a 8sideways0 position1 turning towards us half her bright side and half her dark side4 ,then she journeys on1 with lessening rim of light1 till it vanishes1 and once more we have the dark1 invisible 8new moon40 ,it was these phases and aspects of the moon which formerly gave birth to the custom of measuring time by months1 and by weeks of seven days1 on account of the return of the moon's phases in a month1 and because the moon appears about every seven days1 so to say1 under a new form4 ,such was the first measure of time2 there was not in the sky any signal of which the differences1 the alternations1 and the epochs were more remarkable4 ,families met together at a time fixed by some lunar phase4 ,the new moons served to regulate assemblies1 sacrifices1 and public functions4 ,the ancients counted the moon from the day they first perceived it4 ,in order to discover it easily1 they assembled at evening upon the heights4 ,the first appearance of the lunar crescent was watched with care1 reported by the high priest1 and announced to the people by the sound of trumpets4 ,the new moons which correspond with the renewal of the four seasons were the most solemn2 we find here the origin of the 8ember weeks0 of the ,church1 as we find that of most of our festivals in the ceremonies of the ancients4 ,the ,orientals1 the ,chaldeans1 ,egyptians1 and ,jews religiously observed this custom4 ,an eclipse of the sun has already been described4 ,an eclipse of the moon is an equally simple matter4 ,an eclipse of the sun is caused by the dark1 solid body of the moon passing just between earth and sun1 hiding the sun from us1 and casting its shadow upon the earth4 ,an eclipse of the moon is also caused by a shadow--the shadow of our own earth--falling upon the moon4 ,here again1 if the plane of the moon's orbit were the same as ours1 eclipses of the moon would be very common4 ,as it is1 her orbit carries her often just a little too high or too low to be eclipsed1 and it is only now and then1 at regular intervals1 that she passes through the shadow of the earth4 ,if a large1 solid ball is hung up in the air1 with bright sunlight shining on it1 the sunlight will cast a cone of shadow behind the ball4 ,it will throw1 in a direction just away from the sun1 a long1 round shadow1 the same as the ball at first1 but tapering gradually off to a point4 ,if the ball is near the ground1 a round shadow will rest there1 almost as large as the ball4 ,the higher the ball is placed1 the smaller will be the round shadow1 till at length1 if the ball be taken far enough upwards1 the shadow will not reach the ground at all4 ,our earth and all the planets cast just such tapering cones of dark shadow behind them into space4 ,the cone always lies in a direction away from the sun4 ,it is when the moon comes into this shadow that an 8eclipse of the moon0 takes place4 ,sometimes she only dips half-way into it1 or just grazes along the edge of it1 and that is called a 8partial eclipse40 ,sometimes she goes in altogether1 straight through the midst of the shadow1 so that the whole of her bright face for a short time grows quite dark4 ,then we have a 8total lunar eclipse40 ,,chapter ,,xv4 ,,yet ,,more ,,about ,,the ,,moon4 ,there are two ways of thinking about the moon4 ,one way is to consider her as merely the earth's attendant satellite4 ,the other way is to consider her as our sister-planet1 traveling with us round the central sun4 ,the first is the more common view2 but the second is just as true as the first4 ,for the sun does actually pull the moon towards himself1 with a very much stronger pulling than that of the earth4 ,the attraction of the sun for the moon is more than double the attraction of the earth for the moon4 ,if it were not that he pulls the earth quite as hard as he pulls the moon1 he would soon overpower the earth's attraction1 and drag the moon away from us altogether4 ,people are often puzzled about the orbit or pathway of the moon through the heavens4 ,for in one sense they have to think of her as traveling round and round in a fixed orbit1 with the earth in the center4 ,in another sense they have to think of her as always journeying onwards with the earth in her journey round the sun1 and thus never returning to the same point4 ,there are two ways of meeting this difficulty4 ,first of all1 remember that the one movement does not interfere with the other4 ,just as in the case of the earth traveling round the sun1 and also traveling onward with him through space2 just as in the case of a boy walking round and round a mast1 and also being borne onwards by the moving vessel1--so it is here4 ,the two movements are quite separate and independent of each other4 ,as regards the earth alone1 the moon journeys round and round perpetually1 not in a circle1 but in a pathway which comes near being an ellipse4 ,as regards the actual line which the moon's movements may be supposed to draw in space1 it has nothing elliptical about it1 since no one point of it is ever reached a second time by the moon4 ,but according to this last view of the question1 nobody ever can or will walk in a circle or an oval4 ,take a walk round your grass-plot1 measuring your distance carefully at all points from the center4 ,is that a circle8 ,all the while you moved1 the surface of the earth was rushing along and bearing you with it1 and the whole earth was hurrying round the sun1 and was being also carried by him in a third direction4 ,whatever point in space you occupied when you started1 you can never fill that particular part of space again4 ,the two ends of your so-called circle can never be joined4 ,but then you may come back to the same point on the grass1 as that from which you started4 ,and this is all that really signifies4 ,practically you have walked in a circle4 ,though not a circle as regards space generally1 it is a circle as regards the earth4 ,so also the moon comes back to the same point in her orbit round the earth4 ,letting alone the question of space1 and considering only the earth1 the moon has--roughly speaking--journeyed in an ellipse4 ,you may1 however1 look at this matter in quite another light4 ,forget about the moon being the earth's satellite1 and think of earth and moon as two sister-planets going round the sun in company4 ,the earth1 it is true1 attracts the moon4 ,so1 also1 the moon attracts the earth2 though the far greater weight of the earth makes her attraction to be far greater4 ,if earth and moon were of the same size1 they would pull each other with equal force4 ,but though the pull of the earth upon the moon is strong1 the pull of the sun upon the moon is more than twice as strong4 ,and greatly as the earth influences the moon1 yet the actual center of the moon's orbit is the sun1 and not the earth4 ,just as the earth travels round the sun1 so also the moon travels round the sun4 ,the earth travels steadily in her path1 being only a little swayed and disturbed by the attraction of the moon4 ,the moon on the contrary1 while traveling in her orbit1 is very much swayed and disturbed indeed by the earth's attraction4 ,in fact1 instead of being able to journey straight onwards like the earth1 her orbit is made up of a succession of delicate curves or scallops1 passing alternately backwards and forwards over the orbit of the earth4 ,now she is behind the earth2 now in front of the earth2 now between earth and sun2 now outside the earth away from the sun4 ,the order of positions is not as here given1 but each is occupied by her in turn4 ,sometimes she moves quickly1 sometimes she moves slowly1 just according to whether the earth is pulling her on or holding her back4 ,two hundred and forty thousand miles sounds a good deal4 ,that is the distance between earth and moon4 ,but it is1 after all1 a mere nothing1 compared with the ninety-three millions of miles which separate the sun from the earth and moon4 ,if we made a small model1 with the sun in the center1 and the earth and moon traveling a few inches off1 only one slender piece of wire would be needed to represent the path of earth and moon together4 ,for not only would the earth and the moon be so small as to be quite invisible1 but the whole of the moon's orbit would have disappeared into the thickness of the single wire4 ,this question of the moon's motions is in its nature intricate1 and in its details quite beyond the grasp of any beginner in astronomy4 ,but so much at least may be understood1 that though the earth's attraction powerfully affects the moon1 and causes in her motions perturbations1 such as have been already spoken about as taking place among the planets1 yet that in reality the great controlling power over the moon is the attraction of the sun4 ,the tides of the ocean are chiefly brought about by the moon's attraction4 ,the sun has something to do with the matter1 but the moon is the chief agent4 ,this action of the moon can best be seen in the southern hemisphere1 where there is less land4 ,as the moon travels slowly round the earth1 her attraction draws up the yielding waters of the ocean in a vast wave which travels slowly along with her4 ,the same pulling which thus lifts a wave on the side of the earth towards the moon1 also pulls the earth gently away from the water on the opposite side1 and causes a second wave there4 ,the parts of the ocean between these two huge waves are depressed1 or lower in level4 ,these two waves on the opposite sides of the earth sweep steadily onwards1 following the moon's movements1--not real1 but seeming movements1 caused by the turning of the earth upon her axis4 ,once in every twenty-four hours these wide waves sweep round the whole earth in the southern ocean4 ,they can not do the same in the north1 on account of the large continents1 but offshoots from the south waves travel northwards1 bringing high-tide into every sea and ocean inlet4 ,if there were only one wave1 there would be only one tide in each twenty-four hours4 ,as there are two waves1 there are two tides1 one twelve hours after the other4 ,in the space between these two high-tides we have low-tide4 ,twice every month we have very high and very low tides4 ,twice every month we have tides not so high or so low4 ,the highest are called 8spring-tides10 and the lowest 8neap-tides40 ,when the moon is between us and the sun1 or when she is 8new moon10 there are spring-tides2 for the pull or attraction of sun and moon upon the ocean act exactly together4 ,it is the same at full moon1 when once more the moon is in a straight line with earth and sun4 ,but at the first and last quarters1 when the moon has her sideways position1 and when the sun pulls in one direction and the moon pulls in another1 each undoes a little of the other's work4 ,then we only have neap-tides2 for the wave raised is smaller1 and the water does not flow so high upon our shores4 ,in speaking of the surface of the moon1 we are able only to speak about one side4 ,the other is entirely hidden from us4 ,this is caused by the curious fact that the moon turns on her axis and travels round the earth in exactly the same length of time4 ,one-half of the moon is thus always turned towards us1 though of that half we can only see so much as is receiving the light of the sun4 ,but the half turned in our direction is always the same half4 ,one part of the moon--not quite so much as half1 though always the same portion--is turned away from us4 ,a small border on each side of that part becomes now and then visible to us1 owing to certain movements of the earth and the moon4 ,what sort of a landscape may lie in the unknown district1 it is idle to imagine4 ,many guesses have been made4 ,some have supposed it possible that air might be found there2 that water might exist there2 that something like earthly animals might live there4 ,it is difficult to say what may not be1 in a place about which we know nothing whatever4 ,but judging from our earthly experience1 nothing seems more unlikely than that air1 water1 clouds1 should be entirely banished from over one-half of a globe1 and collected together in the space remaining4 ,we are on safer ground when we speak about that part of the moon which is turned towards us4 ,for we can say with confidence that if any atmosphere exist there1 it must be in thickness less than the two-thousandth part of our earthly atmosphere4 ,it seems equally clear that water also must be entirely wanting4 ,the tremendous heat of the long lunar day would raise clouds of vapor1 which could not fail to be visible4 ,but no such mistiness ever disturbs the sharply-defined outline of the moon1 and no signs of water action are seen in the craggy mountains and deep craters4 ,illustration3 ,,the ,,lunar ,,crater ,,copernicus4 ,the craters which honeycomb the surface of the moon are various in size4 ,many of the larger ones are from fifty to a hundred miles in diameter4 ,these huge craters--or1 as we may call them1 deep circular plains--are surrounded by mighty mountain ramparts1 rising to the height of thousands of feet4 ,usually they have in their center a sugar-loaf or cone-shape mountain1 or even two or more such mountains1 somewhat lower in height than the surrounding range4 ,the sunset-lights upon certain of these distant mountain-peaks were first watched by ,galileo through his telescope1 and have since been seen by many an observer--intense brightness contrasting with intense blackness of shadow4 ,in addition to her great craters1 the moon seems to be thickly covered with little ones1 many of them being as small as can be seen at all through a telescope4 ,whether these are all volcano-craters remains to be discovered4 ,it is not supposed that any of them are now active4 ,from time to time1 signs of faint changes on the moon's surface have been noticed1 which it was thought might be owing to volcanic outbursts4 ,such an outburst as the worst eruptions of ,mount ,vesuvius would be invisible at this distance4 ,but the said changes may be quite as well accounted for by the startling fortnightly variations of climate which the moon has to endure4 ,the general belief now inclines to the idea that the moon-volcanoes are extinct1 though no doubt there was in the past great volcanic activity there4 ,a description has been given earlier of the rain of meteorites constantly falling to our earth1 and only prevented by the atmosphere from becoming serious4 ,but the moon has no such protecting atmosphere1 and the amount of cannonading which she has to endure must be by no means small4 ,perhaps in past times1 when her slowly-cooling crust was yet soft1 these celestial missiles showering upon her may have occasionally made deep round holes in her surface4 ,this is another guess1 which time may prove to be true4 ,guesses at possible explanations of mysteries do no harm1 so long as we do not accept them for truth without ample reason4 ,illustration3 ,,lunar ,,eruption--,,brisk ,,action4 ,the origin of the lunar craters must be referred to some ancient epoch in the moon's history4 ,how ancient that epoch is we have no means of knowing2 but in all probability the antiquity of the lunar craters is enormously great4 ,at the time when the moon was sufficiently heated to have these vast volcanic eruptions1 of which the mighty craters are the survivals1 the earth must have been very much hotter than it is at present4 ,it is not1 indeed1 at all unreasonable to believe that when the moon was hot enough for its volcanoes to be active1 the earth was so hot that life was impossible on its surface4 ,this supposition would point to an antiquity for the moon's craters far too great to be estimated by the centuries and the thousands of years which are adequate for the lapse of time as recognized by the history of human events4 ,it seems not unlikely that millions of years may have elapsed since the mighty craters of ,plato or of ,copernicus consolidated into their present form4 ,illustration3 ,,lunar ,,eruption--,,feeble ,,action4 ,it will now be possible for us to attempt to account for the formation of the lunar craters4 ,the most probable views on the subject are certainly those adopted by ,mr4 ,nasmyth1 as represented in the cuts1 though it must be admitted that they are by no means free from difficulty4 ,we can explain the way in which the rampart around the lunar crater is formed1 and the great mountain which so often adorns the center of the plain4 ,the first of these cuts contains an imaginary sketch of a volcanic vent on the moon in the days when the craters were active4 ,the eruption is here in the full flush of its energy1 when the internal forces are hurling forth a fountain of ashes or stones1 which fall at a considerable distance from the vent2 and these accumulations constitute the rampart surrounding the crater4 ,the second cut depicts the crater in a later stage of its history4 ,the prodigious explosive power has now been exhausted1 and perhaps has been intermitted for some time4 ,a feeble jet issues from the vent1 and deposits the materials close around the orifice1 and thus gradually raises a mountain in the center4 ,besides the craters and their surrounding barriers1 there are ranges of mountains on the moon1 and flat plains which were once named 8seas10 before it was found that water did not exist there4 ,astronomers also see bright ridges1 or lines1 or cracks of light1 hard to explain4 ,one of the chief craters is called 8,ptolemy10 and in size it is roughly calculated to be no less than one hundred and fourteen miles across4 ,another1 8,copernicus10 is about fifty-six miles2 and another1 8,tycho10 about fifty-four miles4 ,the central cone-mountain of ,tycho is five thousand feet high4 ,the crater of 8,schickard0 is supposed to be as much as one hundred and thirty-three miles in diameter4 ,astronomers have agreed to name these craters after the great discoverers who enlarged our knowledge of the solar and sidereal systems4 ,it is fitting that these great names are suggested every time the moon is seen through a telescope4 ,to ,ptolemy we are indebted for what is known as 8,the ,ptolemaic ,system of the ,universe10 which makes the earth the center around which the sun1 moon1 planets1 and stars all revolve1 and explains the apparently erratic movements of the planets by supposing their orbits to be epicycles2 that is1 curves returning upon themselves and forming loops4 ,tycho ,brahe was willing to allow1 with ,copernicus1 that the planets all revolved around the sun2 but he taught that both sun and planets turned around the earth4 ,the system known as 8,the ,copernican0 is now known to be the only true one1 and it is universally accepted4 ,it is so called after ,nicolaus ,copernicus1 who was born in ,thorn1 ,prussia1 ,february #ai1 #adgc4 ,he was educated for the ,church1 and studied medicine1 but devoted himself especially to astronomy4 ,without being precisely a great genius1 this quiet and thoughtful monk seems to have been wise far beyond the age in which he lived1 and remarkable for his independence of mind4 ,he had a 8profound sagacity10 and a wide general grasp of scientific subjects4 ,the extremely complicated and cumbrous nature of the ,ptolemaic system appeared to his judgment hardly compatible with the harmony and simplicity elsewhere characteristic of nature4 ,moreover1 he was impressed and perplexed by the very marked changes in the brilliancy of the planets at different seasons4 ,these changes now are no difficulty at all4 ,venus1 ,mars1 ,jupiter1 when on the same side of the sun as ourselves1 are comparatively near to us1 and naturally look much more bright in consequence of that nearness than when they are on the opposite side of the sun from ourselves4 ,but under the ,ptolemaic system1 each planet was supposed to revolve round our earth1 and to be always at about the same distance from us2 therefore1 why such variations in their brilliancy8 ,illustration3 ,,nicolaus ,,copernicus4 ,during thirty-six long years he patiently worked out this theory1 and during part of those thirty-six years he wrote the one great book of his lifetime1 explaining the newer view of the ,solar ,system which had taken hold of his reason and imagination4 ,this book1 named ,de ,revolutionibus ,orbium ,clestium1 or1 8,concerning the ,revolutions of the ,celestial ,spheres10 which came out only a few hours before his death1 was dedicated to the ,bishop of ,rome--a little touch of worldly wisdom which doubtless staved off for a while the opposition of the ,vatican4 ,copernicus was not the first who thought of interpreting the celestial motions by the theory of the earth's motion4 ,that immortal astronomer has taken care to give1 with rare sincerity1 the passages in the ancient writers from which he derived the first idea of the probability of this motion--especially ,cicero1 who attributed this opinion to ,nicetas of ,syracuse2 ,plutarch1 who puts forward the names of ,philolaus1 ,heraclides of ,pontus1 and ,ecphantus the ,pythagorean2 ,martianus ,capella1 who adopted1 with the ,egyptians1 the motion of ,mercury and ,venus around the sun1 etc4 ,even a hundred years before the publication of the work of ,copernicus1 ,cardinal ,nicolas of ,cusa1 in #addd1 in his great theological and scientific encyclopedia1 had also spoken in favor of the idea of the earth's motion and the plurality of worlds4 ,from ancient times to the age of ,copernicus1 the system of the earth's immobility had been doubted by clear-sighted minds1 and that of the earth's motion was proposed under different forms4 ,but all these attempts still leave to ,copernicus the glory of establishing it definitely4 ,not content with merely admitting the idea of the earth's motion as a simple arbitrary hypothesis1 which several astronomers had done before him1 he wished--and this is his glory--to demonstrate it to himself by acquiring the conviction by study1 and wrote his book to prove it4 ,the true prophet of a creed1 the apostle of a doctrine1 the author of a theory1 is the man who1 by his works1 demonstrates the theory1 makes the creed believed in1 and spreads the doctrine4 ,he is not the creator4 8,there is nothing new under the sun10 says an ancient proverb4 ,we may rather say1 ,nothing which succeeds is entirely new4 ,the newborn is unformed and incapable4 ,the greatest things are born from a state of germ1 so to say1 and increase unperceived4 ,ideas fertilize each other4 ,the sciences help each other2 progress marches4 ,men often feel a truth1 sympathize with an opinion1 touch a discovery1 without knowing it4 ,the day arrives when a synthetical mind feels in some way an idea1 almost ripe1 becoming incarnate in his brain4 ,he becomes enamored of it1 he fondles it1 he contemplates it4 ,it grows as he regards it4 ,he sees1 grouping round it1 a multitude of elements which help to support it4 ,to him the idea becomes a doctrine4 ,then1 like the apostles of good tidings1 he becomes an evangelist1 announces the truth1 proves it by his works1 and all recognize in him the author of the new contemplation of nature1 although all know perfectly well that he has not invented the idea1 and that many others before him have foreseen its grandeur4 ,such is the position of ,copernicus in the history of astronomy4 ,the hypothesis of the earth's motion had been suggested long before his birth on this planet4 ,this theory counted partisans in his time4 ,but he--he did his work4 ,he examined it with the patience of an astronomer1 the rigor of a mathematician1 the sincerity of a sage1 and the mind of a philosopher4 ,he demonstrated it in his works4 ,then he died without seeing it understood1 and it was not till a century after his death that astronomy adopted it1 and popularized it by teaching it4 ,however1 ,copernicus is really the author of the true system of the world1 and his name will remain respected to the end of time4 ,the so-called 8seas0 on the moon are those large dark spots to be seen on its surface1 in the shape of 8eyes1 nose1 and mouth10 or of the famous old man with his bundle of sticks4 ,the brighter parts are the more mountainous parts4 ,the chief ranges of lunar mountains have been named by astronomers after mountains on earth1 such as the ,apennines1 the ,alps1 the ,caucasian range1 the ,carpathian and the ,altai ,mountains4 ,,chapter ,,xvi4 ,,mercury1 ,,venus1 ,,and ,,mars4 ,once again we have to journey through the high-roads of the ,solar ,system1 paying a brief visit to each in turn of our seven chief brother-and-sister planets1 and learning a few more leading facts about them4 ,having gone the same way before1 it will not now seem quite so far4 ,busy1 hurrying ,mercury6 we must meet him first in his wild rush through space4 ,if he were to slacken speed for a single instant1 he would begin to fall with fearful rapidity towards the sun4 ,and if ,mercury were to drop into one of those huge black chasms of rent furnace-flame on the sun's surface1 there would be a speedy end to his life as a planet4 ,mercury's day is about the same length as our day1 and his year is about one quarter the length of our year4 ,if ,mercury has spring1 summer1 autumn1 and winter1 each season must be extremely short2 but this depends upon whether ,mercury's axis slopes like the earth's axis--a matter difficult to find out4 ,mercury is always so near to the sun1 that it is by no means easy to observe him well4 ,we know more about his orbit than his axis4 ,the earth's orbit1 as before explained1 is not a circle1 but an ellipse or oval4 ,mercury's orbit is an ellipse also1 and a much longer--or1 as it is called1 a more eccentric--ellipse4 ,the earth is three millions of miles nearer to the sun at one time of the year1 than six months before or after4 ,mercury is no less than fifteen millions of miles nearer at one time than another1 which must make a marked difference in the amount of heat received4 ,even when the distance is greatest1 the sun as seen from ,mercury looks four and a half times as large as the sun we see4 ,what a blazing splendor of light6 ,it is not easy to imagine human beings living there1 in such heat and glare1 and with either no changes of season at all1 or such very short seasons rapidly following one another4 ,mercury may1 and very likely does1 abound with living creatures1 as much as the earth abounds with them2 only one fancies they must be altogether a different kind of living creatures from any ever seen on earth4 ,and yet we do not know4 ,man can so wonderfully adapt himself or be adapted to different climates on earth1 from extreme heat to extreme cold1 that we can not tell how far this adapting power may reach4 ,both ,mercury and ,venus seem to be enfolded in dense1 cloud-laden atmospheres1 rarely parting so as to allow us to get even a glimpse of the real planets within the thick1 light-reflecting covering4 ,some have thought that a heavy1 moist1 protecting atmosphere may help to ward off the intense heat1 and to make ,mercury a more habitable place4 ,our earthly atmosphere is rather of a kind to store up heat1 and to make us warmer than we should be without it2 but there might be vapors differently constituted which might act in some other way4 ,at all events1 we know how easily ,god can have adapted either the planet to the creatures he meant to place there1 or the creatures to the climate4 8,all things are possible0 to him4 ,the how and the what are interesting questions for us1 but we must often be content to wait for an answer4 ,a thick1 gray ring or belt has been noticed round the small1 black disk of ,mercury1 while it has passed between us and the sun4 ,the edge of ,mercury1 seen against the bright photosphere beyond1 would1 if there were no atmosphere1 be sharp and clear as the edge of the airless moon4 ,this surrounding haze seems to show that ,mercury has an atmosphere4 ,the sunlight reflected from ,mercury's envelope of clouds shines at least as brightly as if it were reflected from his solid body4 ,the small size of ,mercury makes attraction on his surface much less than on earth4 ,a lump of iron weighing on earth one pound1 would weigh on ,mercury only about seven ounces1 or less than half as much4 ,so a man would be a very light leaper indeed there1 and an elephant might be quite a frolicsome animal4 ,if there are star-gazers in ,mercury1 and if the cloud-laden atmosphere allows many clear views of the sky1 the earth and ,venus must both be beautiful to look upon4 ,each of the two would shine far more brightly than ,jupiter1 as seen at his best from earth4 ,like ,mercury1 ,venus1 the next planet1 has an orbit lying inside our orbit4 ,mercury and ,venus are always nearer to the sun than we are2 and if ,mercury and ,venus traveled round the sun in orbits1 the planes of which were exactly the same as the plane of the earth's orbit1 we should very often see them creeping over the surface of the sun4 ,not that they really 8creep over0 it2 only1 as they journey between the sun and us1 we can see them pass like little black dots across the sun's disk4 ,this is the same thing as when the moon passes across the sun's disk and eclipses it4 ,but ,mercury and ,venus are too far away from us to cause any eclipse of the sun's light4 ,mercury has given more trouble to astronomers than any other member of the system2 for1 owing to his proximity to the sun1 he is usually lost in the solar glory1 and is never seen in a dark part of the heavens1 even at the time of his greatest distance4 ,this circumstance1 together with a small mass and an immense velocity1 renders it difficult to catch and watch him4 ,in high latitudes1 where the twilight is strong and lengthened1 while mists often overhang the horizon1 the planet can seldom be seen with the naked eye4 ,hence an old astro-meteorologist contemptuously describes him as 8a squirting lacquey of the sun1 who seldom shows his head in these parts1 as if he was in debt40 ,copernicus lamented that he had never been able to obtain a sight of ,mercury2 and the ,french astronomer ,delambre saw him not more than twice with the naked eye4 ,the most favorable times for making observations are about an hour and three-quarters before sunrise in autumn1 and after sunset in spring2 but very clear weather and a good eye are required4 ,at certain periods1 when between the earth and the sun1 on a line joining the centers of the two bodies1 ,mercury appears projected on the solar disk as a small1 round1 dark spot4 ,this is called a transit1 and would occur during every revolution if the plane of his orbit coincided with that of the orbit of the earth4 ,but as one-half of his orbit is a little above that of the earth1 and the other half a little below it1 he passes above or below the sun to the terrestrial spectator1 except at those intervals1 when1 being between us and the sun1 he is also at one of the two opposite points where the planes of the respective orbits intersect each other4 ,then1 stripped of all luster1 the planet passes over the face of the great luminary as a black circular speck1 affording evidence of his shining by reflected light1 and of his spherical form4 ,the first transit of ,mercury recorded in history was predicted by ,kepler1 and witnessed by ,gassendi1 at ,paris1 on the morning of a cloudy day1 the #gth of ,november1 #afca4 ,it was toward nine o'clock when he saw the planet2 but owing to its extreme smallness1 he was at first inclined to think it was a minute solar spot4 ,it was then going off the sun2 and made its final egress toward half-past ten4 ,the observed time of the transit was nearly five hours in advance of the computed time4 ,this was a very satisfactory accordance for that age between theory and observation2 but it was the effect of a fortuitous combination of circumstances1 rather than of computations founded upon well-established data4 8,the crafty god10 wrote ,gassendi1 in the peculiar style of his day1 8had sought to deceive astronomers by passing over the sun a little earlier than was expected1 and had drawn a veil of dark clouds over the earth in order to make his escape more effectual4 ,but ,apollo1 knowing his knavish tricks from his infancy1 would not allow him to pass altogether unnoticed4 ,to be brief1 ,i have been more fortunate than those hunters after ,mercury who have sought the cunning god in the sun4 ,i found him out1 and saw him where no one else had hitherto seen him40 ,since ,gassendi's time a number of transits have been observed4 ,these crossings of the sun's face1 or 8transits10 as they are called1 have been important matters4 ,the transit of ,venus especially was once eagerly looked for by astronomers1 since1 by close observations of ,venus's movements and positions1 the distance of the sun could at that time be better calculated than in any other way4 ,other methods are now coming into vogue4 ,the transits of ,venus are rare4 ,two come near together1 separated by only eight years1 and then for more than one hundred years the little dark body of ,venus is never seen from earth to glide over the sun's photosphere4 ,there was a transit of ,venus in the year #agfa1 and another in the year #agfi4 ,there was a transit of ,venus in #ahgd1 and another in #ahhb4 ,at the last transits it was found that the sun1 instead of being ninety-five millions of miles away1 as astronomers thought1 was only ninety-three millions of miles away4 ,the reason why these transits happen so seldom1 is that the orbits of ,mercury and ,venus lie in rather a different plane or level from the earth's orbit4 ,so1 like the moon1 though often passing between us and the sun1 they generally go just a little higher or just a little lower than his bright face4 ,mercury and ,venus show phases like the moon1 although they do not circle round the earth as the moon does4 ,these 8phases10 or changes of shape1 are probably never visible except through a telescope4 ,it will be easier to think about the phases of ,venus alone1 than to consider both together4 ,her orbit lies within the earth's orbit1 and the earth and ,venus travel round the sun--as do all the planets--in the same direction4 ,but as ,venus's pathway is shorter than ours1 and as her speed is greater1 she is much the quickest about her yearly journey1 and she overtakes us again and again at different points of our orbit in turn4 ,illustration3 ,,phases ,,of ,,venus4 ,at one time she comes between us and the sun4 ,that is her nearest position to us1 and she is then only about twenty-five millions of miles distant4 ,a beautiful sight she would be1 but unfortunately her bright side is entirely turned away1 and only her dark side is turned towards us4 ,so then she is 8new ,venus10 and is invisible4 ,at another time she is completely beyond the sun1 and at her farthest position away from us4 ,her shining is quite lost in the sun's rays coming between4 ,and though we get a good view of her as 8full ,venus10 at a little to one side or the other1 yet so great is her distance--as much as one hundred and fifty-seven millions of miles--that her size and brightness are very much lessened4 ,between these two nearest and farthest points1 she occupies two middle distances1 one on each side of the sun4 ,then1 like the moon at her 8quarters10 she turns to us only half of her bright side4 ,but this is the best view of ,venus that we have1 as a brilliant1 untwinkling1 starlike form1--the ,evening ,star of ancients and of poets4 ,between these four leading positions ,venus is always traveling gradually from one to another--always either waxing or waning in size and in brightness4 ,mercury passes through the same seeming changes4 ,inhabitants of ,venus must have a glorious view of the earth1 with her attendant moon4 ,for just at the time when the two planets are nearest together1 and when she is only 8new ,venus0 to us1 a dark and invisible body1 the earth is 8full earth0 to ,venus4 ,the very best sight we ever have of ,venus can not come near that sight4 ,but if ,mercury and ,venus really are so often covered with heavy clouds as astronomers believe1 this must greatly interfere with any habits of star-gazing4 ,venus and the earth have often been called twin-sister planets4 ,there are many points of likeness between them4 ,in size they differ little1 and in length of day they are within an hour of being the same4 ,earth certainly has a companion-moon1 and ,venus1 it is believed1 has not4 ,at one time several astronomers were pretty certain that they had caught glimpses of a moon2 but the supposed moon has of late quite vanished1 and nobody can say whether it ever really existed4 ,venus travels in an ellipse which comes nearer to being a circle than the orbit of any other planet4 ,mountain-shadows have been watched through the telescope1 in ,venus1 as in the moon4 ,some astronomers have believed that they saw signs of very lofty mountains--as much as twenty-eight miles1 or four times the height of our highest earthly mountains1 but this requires confirmation4 ,there is a good deal of uncertainty about the climate of ,venus4 ,the heat there must greatly surpass heat ever felt on earth--the sun being about double the apparent size of our sun1 and pouring out nearly double the amount of light and heat that we receive4 ,this difference may be met1 as already stated1 by a sheltering1 cloudy atmosphere1 or the inhabitants may have frames and eyesight suited to the increased glare and warmth4 ,an atmosphere and water exist there as here4 ,from what we have seen above of the rapid and violent seasons of this planet1 we might think that the agitations of the winds1 the rains1 and the storms would surpass everything which we see and experience here1 and that its atmosphere and its seas would be subject to a continual evaporation and precipitation in torrential rains--an hypothesis confirmed by its light1 due1 doubtless1 to reflection from its upper clouds1 and to the multiplicity of the clouds themselves4 ,to judge by our own impressions1 we should be much less pleased with this country than with our own1 and it is even very probable that our physical organization1 accommodating and complaisant as it is1 could not become acclimatized to such variations of temperature4 ,but it is not necessary to conclude from this that ,venus is uninhabitable and uninhabited4 ,we may even suppose1 without exaggeration1 that its inhabitants1 organized to live in the midst of these conditions1 find themselves at their ease1 like a fish in water1 and think that our earth is too monotonous and too cold to serve as an abode for active and intelligent beings4 ,of what nature are the inhabitants of ,venus8 ,do they resemble us in physical form8 ,are they endowed with an intelligence analogous to ours8 ,do they pass their life in pleasure1 as ,bernardin de ,st4 ,pierre said2 or1 rather1 are they so tormented by the inclemency of their seasons that they have no delicate perception1 and are incapable of any scientific or artistic attention8 ,these are interesting questions1 to which we have no reply4 ,all that we can say is1 that organized life on ,venus must be little different from terrestrial life1 and that this world is one of those which resemble ours most4 ,it should1 then1 be inhabited by vegetable1 animal1 and human races but little different from those which people our planet4 ,as to imagining it desert or sterile--this is an hypothesis which could not arise in the brain of any naturalist4 ,the action of the divine sun must be there1 as in ,mercury1 still more fertile than his terrestrial work1 already so wonderful4 ,we may add that ,venus and ,mercury1 having been formed after the earth1 are relatively younger than our planet4 ,it is believed also that the axis of ,venus1 instead of being slanted only as much as the earth's axis1 is tilted much more4 ,even if the tilting is less than some have supposed1 it is probably very considerable4 ,if ,venus really does 8lie over0 in such a manner1 certain startling changes of climate on its surface--unpleasant changes1 according to our ideas--would take place4 ,like earth1 ,venus would have her two arctic regions1 where a burning summer's day would succeed a bitter winter's night1 each half a year in length4 ,she would have also her tropical region--only in that region intense cold would alternate with intense heat1 brief seasons of each in turn4 ,and between the tropics and the arctic regions would lie wide belts1 by turns entirely tropical and entirely arctic4 ,the rapidity and severity of these changes1 following one another in a year about as long as eight of our months1 would seem to be too much for any human frame to endure4 ,but it all rests upon an if4 ,and we may be quite sure that if there are any manner of human beings in ,venus1 their frames are well suited to the climate of their world4 ,though ,mars is one of the inner group of four small planets1 divided by the zone of asteroids from the outer group of four great planets1 yet he belongs to the outside set of ,superior ,planets4 ,his orbit surrounds ours1 being at all points farther off from the sun4 ,very slight 8phases0 have been seen in ,mars4 ,he turns to us1 from time to time1 just enough of his dark side to prove that he has a dark side1 and that he does not shine like a star by his own light4 ,but the phases on that planet are by no means marked as they are with ,venus4 ,until lately it was believed that ,mars possessed no moons4 ,two very small ones have1 however1 been lately found circling round him4#b ,they have been named ,deimos and ,phobos1 after the 8sons of ,mars0 in ,greek mythology4 ,deimos travels round ,mars in thirty-nine hours1 while ,phobos performs the same journey in the astonishingly short period of seven hours and a half6 #b ,the discovery of the two moons is due to the agency of a woman4 ,professor ,asaph ,hall1 of ,washington ,city1 was searching by the aid of the most powerful telescope which had yet been directed to ,mars1 and at the very moment when the planet was in the most favorable condition for observation4 ,having searched in vain during several evenings in ,august1 #ahgg1 he was about to give up1 when ,mrs4 ,hall begged him to search a little more4 ,he did so1 and on the night of the #aath he discovered the first of the satellites1 and then on the #agth the second4 ,illustration3 ,,mars ,,and ,,the ,,path ,,of ,,its ,,satellites4 ,we have here1 then1 a system very different from that of the earth and moon4 ,but the most curious point is the rapidity with which the inner satellite of ,mars revolves round its planet4 ,this revolution is performed in seven hours1 thirty-nine minutes1 fifteen seconds1 although the world of ,mars rotates on itself in twenty-four hours1 thirty-seven minutes--that is to say1 this moon turns much more quickly than the planet itself4 ,this fact is inconsistent with all the ideas we have had up to the present on the law of formation of the celestial bodies4 ,thus1 while the sun appears to revolve in the ,martian sky in a slow journey of more than twenty-four hours1 the inner moon performs its entire revolution in a third of a day4 ,it follows that it rises in the west and it sets in the east6 ,it passes the second moon1 eclipses it from time to time1 and goes through all its phases in eleven hours1 each quarter not lasting even three hours4 ,what a singular world6 ,these satellites are quite small--they are the smallest celestial bodies we know4 ,the brightness of the planet prevents us from measuring them exactly4 ,it seems1 however1 that the nearer is the larger1 and shows the brightness of a star of the tenth magnitude1 and that the second shines as a star of the twelfth magnitude4 ,according to the most trustworthy photometric measures1 the first satellite may have a diameter of #g4de miles1 and the second a diameter of #f4b miles4 ,the larger of these two worlds is scarcely larger than ,paris4 ,should we honor them with the title of worlds8 ,they are not even terrestrial continents1 nor empires1 nor kingdoms1 nor provinces1 nor departments4 ,alexander1 ,csar1 ,charlemagne1 or ,napoleon1 might care but little to receive the scepter of such worlds4 ,gulliver might juggle with them4 ,who knows1 however8 ,the vanity of men being generally in the direct ratio of their mediocrity1 the microscopical reasoning mites which doubtless swarm on their surface have also1 perhaps1 permanent armies1 which mutilate each other for the possession of a grain of sand4 ,these two little moons received from their discoverer the names of ,deimos 7,terror7 and ,phobos 7,flight71 suggested by the two verses of ,homer's 8,iliad0 which represent ,mars descending on the earth to avenge the death of his son ,ascalaphus3 8,he ordered ,terror and ,flight to yoke his steeds1 ,and he himself put on his glittering arms40 ,phobos is the name of the nearer satellite2 ,deimos1 that of the more distant4 ,the existence of these little globes had already been suspected from analogy1 and thinkers had frequently suggested that1 since the earth has one satellite1 ,mars should have two1 ,jupiter four1 ,saturn eight2 and this is indeed the fact--though as ,jupiter is now found to have five satellites1 this arithmetical progression is upset4 ,but as we experience too often in practice the insufficiency of these reasonings of purely human logic1 we can not give them more value than they really possess4 ,we might suppose in the same way now that ,uranus has sixteen satellites1 and ,neptune thirty-two4 ,this is possible2 but we know nothing of them1 and have not even the right to consider this proportion as probable4 ,it is not the less curious to read the following passage1 written by ,voltaire in #agej in his masterpiece1 the 8,micromgas30 8,on leaving ,jupiter1 our travelers crossed a space of about a hundred millions of leagues1 and reached the planet ,mars4 ,they saw two moons1 which wait on this planet1 and which have escaped the gaze of astronomers4 ,i know well that ,father ,castel wrote against the existence of these two moons2 but ,i agree with those who reason from analogy4 ,these good philosophers know how difficult it would be for ,mars1 which is so far from the sun1 to get on with less than two moons4 ,however this may be1 our people found it so small that they feared they might not find anything to lie upon1 and went on their way40 ,here we have unquestionably a very clear prophecy1 a rare quality in this kind of writing4 ,the astronomico-philosophical romance of 8,micromgas0 has been considered as an imitation of ,gulliver4 ,let us open the masterpiece of ,swift himself1 composed about #agbj1 and we read1 word for word1 in ,chapter ,,iii of the 8,voyage to ,laputa30 8,certain astronomers 444 spend the greatest part of their lives in observing the celestial bodies1 which they do by the assistance of glasses far excelling ours in goodness4 ,for this advantage hath enabled them to extend the discoveries much farther than our astronomers in ,europe2 for they have made a catalogue of ten thousand fixed stars1 whereas the largest of ours do not contain above one-third part of that number4 ,they have likewise discovered two lesser stars1 or satellites1 which revolve about ,mars1 whereof the innermost is distant from the center of the primary planet exactly three of his diameters1 and the outermost five4 ,the former revolves in the space of ten hours1 and the latter in twenty-one and a half2 so that the squares of their periodical times are very near in the same proportion with the cubes of their distance from the center of ,mars1 which evidently shows them to be governed by the same law of gravitation that influences the other heavenly bodies40 ,what are we to think of this double prediction of the two satellites of ,mars8 ,indeed1 the prophecies which have been made so much of in certain doctrinal arguments have not always been as clear1 nor the coincidences so striking4 ,however1 it is evident that no one had ever seen these satellites before #ahgg1 and that there was in this hit merely the capricious work of chance4 ,we may even remark that both the ,english and ,french authors have only spoken ironically against the mathematicians1 and that in #afaj1 ,kepler1 on receiving the news of the discovery of the satellites of ,jupiter1 wrote to his friend ,wachenfals that 8not only the existence of these satellites appeared to him probable1 but that doubtless there might yet be found two to ,mars1 six or eight to ,saturn1 and perhaps one to ,venus and ,mercury40 ,we can not1 assuredly1 help noticing that reasoning from analogy is here found on the right road4 ,however this may be1 this discovery truly constitutes one of the most interesting facts of contemporary astronomy4 ,mars is not only much smaller than the earth1 but a good deal less dense in his 8make40 ,his material is only about three-quarters as heavy as an equal amount of the earth's material4 ,a very heavy man on earth would be a most light and active individual on ,mars4 ,gold taken from earth to ,mars would weigh there no more than tin weighs upon earth4 ,mars has1 it seems1 an atmosphere1 even as earth has4 ,of all the planets ,mars1 is the only one whose actual surface is discernible in the telescope4 ,mercury and ,venus are so hidden by dense envelopes of clouds that the real planets within are only now and then to be dimly caught sight of4 ,jupiter and ,saturn are so completely enwrapped in mighty masses of vapor1 that we can not even be certain whether there are any solid bodies at all inside4 ,but ,mars can be studied4 ,here and there1 it is true1 clouds sweep over the landscape1 hiding from view for a little while one continent or another1 one sea or another1 growing1 changing1 melting away1 as do the clouds of earth4 ,still1 though these clouds come and go1 there are other markings on the surface of ,mars which do not change4 ,or1 rather1 they only change so much as the continents and oceans of earth would seem to vary1 if watched from another planet1 as the daily movement of earth carried them from west to east1 or as they might be hidden for a while by cloud-layers coming between4 ,it has been curiously noted that these clouds over ,mars form often in the morning and evening1 and are afterwards dispersed by the heat of midday4 ,also there seems every reason to believe that rainfalls take place in ,mars as upon earth4 ,the red color of ,mars is well known4 ,this does not vanish in the telescope1 but it is found that parts only have the red or orange hue1 while other parts are dark and greenish4 ,these are the markings which remain always the same1 and they have been so closely examined that more is known about the geography of ,mars than of any other world outside our own4 ,mars1 at his nearest point1 does not draw closer to us than forty millions of miles4 ,at such a distance one must not speak too confidently4 ,there are1 however1 many reasons for believing that the red portions are continents and that the green portions are oceans4 ,the spectroscope has lately shown us that water does really exist in the atmosphere of ,mars--unlike the dreary1 waterless moon4 ,so we no longer doubt that the cloudlike appearances are clouds1 and that rain sometimes falls on ,mars4 ,if there is rain1 and if there are clouds and vapor1 there are probably oceans also4 ,two singular white spots are to be seen at the north and south poles1 which we believe to be polar ice and snow4 ,somebody looking at our earth in like manner from a distance1 would doubtless perceive two such white snow-spots4 ,these two polar caps are seen to vary with the seasons4 ,when the north pole of ,mars is turned towards the sun1 the white spot there grows smaller2 and at the same time1 the south pole of ,mars being turned away from the sun1 the white spot there grows larger4 ,again1 when the south pole is towards the sun1 and the north pole away from the sun1 the white spot at the south is seen to be the smallest1 and the white spot at the north is seen to be the largest4 ,this is exactly what takes place in the summers and winters of our north and south poles4 ,the markings of ,mars have been so carefully studied1 that at last a map has been made of the planet--a map of a world1 never less than forty millions of miles away6 ,names have been given to the continents and oceans--such as ,dawes ,continent1 ,herschel ,continent1 ,de ,la ,rue ,ocean1 ,airy ,sea1 ,huggins ,inlet1 and so on4 ,land and water seem to be very differently arranged on ,mars from what they are on earth4 ,here we have about three times as much water as land1 and to get from one continent to another without crossing the sea is in some cases impossible4 ,but a traveler there might go most conveniently to and fro1 hither and thither1 to all parts of his world1 either on land or on water1 without any change4 ,if he preferred water1 he would never need to set foot on land2 and if he preferred land1 he would never need to enter a boat4 ,the two are so curiously mingled together1 narrow necks of land running side by side with long1 narrow sea-inlets1 that ,atlantic and ,pacific ,oceans are unknown4 ,some have wondered whether the reddish color of the land may be caused by grass and trees being red instead of green4 ,very strange if so it were4 ,but in that case1 no doubt the inhabitants of ,mars would find green just as trying to their eyesight1 as we should find red trying to ours4 ,,chapter ,,xvii4 ,,jupiter4 ,passing at one leap over the belt of tiny asteroids1 about which we know little beyond their general movement1 and the size and weight of a few among them1 we reach at once the giant planet ,jupiter3 ,mighty ,jupiter1 hurrying ever onward1 with a speed1 not indeed equal to that of ,mercury or of our earth1 yet eighty times as rapid as the speed of a cannon-ball6 ,think of a huge body1 equal in bulk to twelve hundred earths1 equal in weight to three hundred earths1 rushing ceaselessly through space1 at the rate of seven hundred thousand miles a day6 ,jupiter's shape is greatly flattened at the poles4 ,he spins rapidly on his axis1 once in nearly ten hours1 and has therefore a five hours' day and a five hours' night4 ,as the slope of his axis is exceedingly slight1 he can boast little or no changes of season4 ,the climate near the poles has never much of the sun's heat4 ,in fact1 all the year round the sun must shine upon ,jupiter much as he shines on the earth at the equinoxes4 ,but the amount of light and heat received by ,jupiter from the sun is only about one twenty-fifth part of that which we receive on earth2 and the sun1 as seen from ,jupiter1 can have but a small1 round surface1 not even one-quarter the diameter of the sun we see in the sky4 ,when looked at with magnifying power1 the bright1 starlike ,jupiter grows into a broad1 softly-shining disk or plate1 with flattened top and bottom1 and five tiny1 bright moons close at hand4 ,sometimes one moon is on one side1 and four are on the other2 sometimes two are one side and three on the other2 sometimes one or more are either hidden behind ,jupiter or passing in front of him4 ,jupiter has also curious markings on his surface1 visible through a telescope4 ,these markings often undergo changes2 for ,jupiter is no chill1 fixed1 dead world1 such as the moon seems to be4 ,illustration3 ,,general ,,aspect ,,of ,,jupiter--,,satellite ,,and ,,its ,,shadow4 ,there are dark belts and bright belts1 usually running in a line with the equator1 from east to west4 ,across the regions of the equator lies commonly a band of pearly white1 with a dark band on either side of 8coppery1 ruddy1 or even purplish0 hue4 ,light and dark belts follow one after another1 up to the north pole and down to the south pole4 ,when we talk of 8north and south poles0 in the other planets1 we merely mean those poles which point towards those portions of the starry heavens which we have chosen to call 8northern0 and 8southern40 ,you know that all the chief planets travel round the sun in very nearly the same plane or flat surface that we do ourselves4 ,that plane is called the 8plane of the ecliptic40 ,suppose that you had an enormous sheet of cardboard1 and that in the middle of this cardboard the sun were fixed1 half his body being above and half below4 ,at a little distance1 fixed in like manner in the card1 would be the small body of the earth1 half above and half below1 her axis being in a slanting position4 ,the piece of cardboard represents what is called in the heavens the plane of the ecliptic--an imaginary flat surface1 cutting exactly through the middle of the sun and of the earth4 ,if the planets all traveled in the same precise plane1 they would all be fixed in the cardboard just like the earth1 half the body of each above and half below4 ,as they do not so travel1 some would have to be placed a little higher1 some a little lower1 according to what part of their orbits they were on4 ,this supposed cardboard 8plane of the ecliptic0 would divide the heavens into two halves4 ,one half1 containing the constellations of the ,great ,bear1 the ,little ,bear1 ,cepheus1 ,draco1 and others1 would be called the ,northern ,heavens4 ,one end of the earth's axis1 pointing just now nearly to the ,polar ,star1 we name the ,north ,pole2 and all poles of planets pointing towards this northern half of the heavens1 are in like manner named by us their north poles4 ,with regard to west and east1 lay in imagination upon this cardboard plane a watch1 with its face upwards2 remembering that all the planets and nearly all the moons of the ,solar ,system are said both to spin on their axes1 and to travel in their orbits round the sun1 from west to east4 ,note how the hands of your watch would move in such a position4 ,the 8west to east0 motions of planets and moons would be in exactly the opposite direction from what the motions of the watch-hands would be4 ,to return to ,jupiter4 ,it is believed that these bands of color are owing to a heavy1 dense atmosphere1 loaded with vast masses of cloudy vapor4 ,by the 8size0 of ,jupiter1 we really mean the size of this outside envelope of clouds4 ,how large the solid body within may be1 or whether there is any such solid body at all1 we do not know4 ,the extreme lightness of ,jupiter1 as compared with his great size1 has caused strong doubts on this head4 ,the white belts are supposed to be the outer side of cloud-masses shining in the sunlight4 ,travelers in the ,alps have seen such cloud-masses1 spreading over the whole country beneath their feet1 white as driven snow1 and shining in the sunbeams which they were hiding from villages below2 or looking like soft masses of cotton-wool1 from which the mountain-peaks rose sharply here and there4 ,the dark spaces between seem to be rifts or breaks in the clouds4 ,whether1 when we look at those dark spaces1 we are looking at the body of ,jupiter1 or only at lower layers of clouds1 is not known4 ,but sometimes blacker spots show upon the dark cloud-belts1 and this seems rather as if they were only lower layers of clouds1 the black spots giving us peeps down into still lower and deeper layers1 or else perhaps to the planet itself4 ,these appearances remind one strongly of the sun-spots1 each with its penumbra1 umbra1 and nucleus4 ,occasionally bright white spots show1 instead of dark ones4 ,it is thought that they may be caused by a violent upward rush of dense clouds of white vapor4 ,the white spots again recall the sun and his facul4 ,jupiter's bands are not fixed4 ,great changes go on constantly among them4 ,sometimes a white band will turn dark-colored1 or a dark band will turn white4 ,sometimes few and sometimes many belts are to be seen4 ,sometimes a dark belt will lie slanting across the others1 nearly from north to south4 ,once1 in a single hour1 an entirely new belt was seen to come into shape4 ,another time1 two whole belts vanished in one day4 ,the bands1 in which such rapid movements are seen1 are often thousands of miles in breadth4 ,sometimes these wide zones of clouds will remain for weeks the same4 ,at another time a break or rift in them will be seen to journey swiftly over the surface of the planet4 ,the winds on earth are often destructive4 ,a hurricane1 moving at the rate of ninety miles an hour1 will carry away whole buildings and level entire plantations4 ,such hurricanes rarely1 if ever1 last more than a few hours4 ,but winds in ,jupiter1 judging from the movements of the clouds1 often travel at the rate of one hundred and fifty miles an hour2 and that1 not for hours only1 but for many weeks together4 ,what manner of living beings could stand such weather may well be questioned4 ,another difficulty which arises is as to the cause of these tremendous disturbances on ,jupiter4 ,our earthly storms are brought about by the heat of the sun acting on our atmosphere4 ,but the sun-heat which reaches ,jupiter seems very far from enough to raise such vast clouds of vapor1 and to bring about such prolonged and tremendous hurricanes of wind4 ,what if there is another cause8 ,what if ,jupiter is not a cooled body like our earth1 but a liquid1 seething1 bubbling mass of fiery heat--just as we believe our earth was once upon a time1 in long past ages1 before her outside crust became cold enough for men and animals to live thereon8 ,then1 indeed1 we could understand how1 instead of oceans lying on his surface1 all the water of ,jupiter would be driven aloft to hang in masses of steam or be condensed into vast cloud-layers4 ,then we could understand why a perpetual stir of rushing winds should disturb the planet's atmosphere4 ,in that case would ,jupiter be a planet at all8 ,certainly--in the sense of obeying the sun's control4 ,our earth was once1 we believe1 a globe of melted matter1 glowing with heat--and farther back still1 possibly1 a globe of gas4 ,some people are very positive about these past changes2 but it is wise not to be over-positive where we can not know to a certainty what has taken place4 ,however1 ,jupiter may have cooled down only to the liquid state1 and if he goes on cooling he may1 by and by1 gain a solid crust like the earth4 ,this idea about ,jupiter's hot and molten state belongs quite to late years4 ,certain other matters seem to bear it out1 though of actual proof we have none4 ,it is thought1 for instance1 that the dull1 coppery red light1 showing often in the dark bands1 may be a red glow from the heated body within4 ,also it has been calculated that ,jupiter gives out much more light than our earth would do1 if increased to his size and moved to his place--more1 in fact1 than we could reasonably expect him to give out4 ,if so1 whence does he obtain the extra brightness8 ,if he does not shine by reflected light alone1 he probably shines also in some additional degree by his own light4 ,but what about ,jupiter being inhabited8 ,would it in such a case be quite impossible8 8,impossible0 is not a word for us to use about matters where we are ignorant4 ,we can only say that it is impossible for us to imagine any kind of living creatures finding a home there1 if our present notions about the present state of ,jupiter are correct4 ,then is the chief planet of the ,solar ,system a huge1 useless monument of ,god's power to create8 ,not so fast4 ,even as merely such a monument1 he could not be useless4 ,and even if he were put to no present use at all1 it might be merely because this is a time of preparation for the future4 ,god has his times of long and slow preparation1 alike with worlds1 with nations1 and with individuals4 ,but now as to the five moons circling round ,jupiter4 ,there used to be some very pretty ideas afloat about the wonderful beauty of the moons1 as seen from ,jupiter1 their united brilliancy so far surpassing the shining of our one poor satellite1 and making up for the dim light of ,jupiter's sun4 ,a certain little difficulty was not quite enough considered4 ,if anybody were living on the surface of ,jupiter1 he would have1 one is inclined to think1 small chance of often seeing the moons through the cloud-laden atmosphere4 ,illustration3 ,,satellites ,,of ,,jupiter ,,compared ,,with ,,the ,,earth ,,and ,,moon4 ,the nearest of the four larger moons to ,jupiter would1 it is true1 appear--when visible at all--rather bigger than ours does to us2 while the two next would be almost half as large1 and the farthest about a quarter as large--supposing inhabitants of ,jupiter to have our powers of vision4 ,all taken together they would cover a considerably larger space in the sky than does our moon4 ,but it must be remembered that ,jupiter's moons1 like ours1 shine merely by reflected sunlight4 ,and so dim is the sunshine at that distance compared with what it is at our distance1 that all the five moons together1 even if full at the same time1 could only give about one-sixteenth part of the light which we obtain from our one full moon4 ,besides1 they never are full together1 seen from any one part of ,jupiter4 ,the four inner moons are never to be seen 8full0 at all2 for just when they might be so1 they are eclipsed or shaded by ,jupiter's shadow4 ,the fourth sometimes escapes this eclipse1 from being so much farther away4 ,a thought has been lately put forward1 which may or may not have truth in it4 ,what if--instead of ,jupiter being a world1 inhabited by animals and people1 as is often supposed1 with a small distant sun and five dim moons to give them light--what if ,jupiter is himself in some sort a second sun to his moons1 and what if those 8moons0 are really inhabited planets8 ,it may be so4 ,that is all we can say4 ,the idea is not an impossible one4 ,the so-called 8moons0 are certainly small4 ,but they are by no means too small for such a purpose4 ,jupiter would in that case1 with his five moons circling round him1 enjoying his light and warmth1 be a small picture of the sun1 with his four inner planets and the asteroids circling round him1 basking in a more lavish amount of the same4 ,picturing the moons as giving light to ,jupiter1 we find them seemingly dim and weak for such a purpose--though1 of course1 we may here make a grand mistake in supposing the eyesight of living creatures in ,jupiter to be no better than our own eyesight4 ,even upon earth a cat can see plainly where a man has to grope his way in darkness4 ,but by picturing the moons as inhabited1 and ,jupiter as giving out some measure of heat and light to make up for the lessened amount of light and heat received from the sun1 the matter becomes more easy to our understanding4 ,illustration3 ,,the ,,system ,,of ,,jupiter4 ,the nearest moon has indeed a magnificent view of ,jupiter as a huge bright disk in its sky1 no less than three thousand times as large as our moon appears to us1 shining brightly with reflected sunlight1 and it may be glowing with a red light of his own in addition4 ,even the farthest off of the five sees him with a face sixty-five times the size of our moon4 ,and the varying colors and stormy changes in the cloud-belts1 viewed thus near at hand1 must afford marvelously beautiful effects4 ,just as ,mercury1 ,venus1 ,earth1 and ,mars travel round the sun1 at different distances1 nearly in the same plane1 so ,jupiter's five moons travel round him1 at different distances1 nearly in the same plane4 ,jupiter's moons are always to be seen in a line1 not one high and another low1 one near his pole and another near his equator4 ,the moon nearest to ,jupiter1 discovered in ,september1 #ahib1 by ,professor ,barnard1 now of the ,yerkes ,observatory of the ,chicago ,university1 has a probable diameter of one hundred miles1 and revolves round its primary in about twelve hours4 ,the second satellite1 named ,io1 is said to be over two thousand miles in diameter1 travels round ,jupiter in less than two of our days1 and is eclipsed by ,jupiter's shadow once in every forty-two hours4 ,the third moon1 ,europa1 is rather smaller1 takes over three days to its journey1 and suffers eclipse once in every eighty-five hours4 ,the fourth moon1 ,ganymede1 is believed to be considerably larger than ,mercury1 journeys round ,jupiter once a week1 and is eclipsed once every hundred and seventy-one hours4 ,the fifth moon1 ,callisto1 is also said to be slightly larger than ,mercury1 performs its journey in something more than sixteen days1 and from its greater distance suffers eclipse less often than the other four4 ,the distance of the nearest is more than one hundred thousand miles from ,jupiter2 that of the farthest1 more than one million miles4 ,the following table presents more minutely the results of the latest discoveries concerning these satellites3 ---------------------------------------- ---------------------- ,,distance ,,from ,,period ,,of ,,satellites4 ,,center ,,of ,,diameter4 ,,revolution4 ,,jupiter4 ---------------------------------------- ---------------------- ,d4 ,h4 ,m4 ,s4 #a4 ,barnard's ,satellite1 #aab1ejj miles4 #ajj miles4 #aa #eg #bc #b4 ,io1 #bff1jjj 0 #b1cef 0 #a #ah #bg #cc #c4 ,europa1 #dbd1jjj 0 #b1jdf 0 #c #ac #ac #db #d4 ,ganymede1 #fgf1jjj 0 #c1eif 0 #g #c #db #cc #e4 ,callisto1 #a1ahi1jjj 0 #b1gbh 0 #af #ae #cb #aa ---------------------------------------- ---------------------- ,the fact of these eclipses1 and of the shadow thrown by ,jupiter's body1 shows plainly that though he may give out some measure of light1 as has been suggested1 yet that light can not be strong1 or it would prevent any shadow from being thrown by the sunlight4 ,also1 the dense masses of cloud around him1 though reflecting sunlight brightly1 would shut in much of his own light4 ,possibly it is chiefly as heat-giver and as sunlight-reflector that ,jupiter serves his five satellites4 ,as with our own moon1 so with ,jupiter's moons1 the real center of their orbit is the sun1 and not ,jupiter4 ,they accompany ,jupiter in his journey1 controlled by the sun1 and immensely influenced by ,jupiter4 ,at night the spectacle of the sky seen from ,jupiter is1 with reference to the constellations1 the same as that which we see from the earth4 ,there1 as here1 shine ,orion1 the ,great ,bear1 ,pegasus1 ,andromeda1 ,gemini1 and all the other constellations1 as well as the diamonds of our sky3 ,sirius1 ,vega1 ,capella1 ,procyon1 ,rigel1 and their rivals4 ,the #cij1jjj1jjj of miles which separate us from ,jupiter in no way alter the celestial perspectives4 ,but the most curious character of this sky is unquestionably the spectacle of the five moons1 each of which shows a different motion4 ,the second moves in the firmament with an enormous velocity1 and ,barnard's satellite still faster1 and produce almost every day total eclipses of the sun in the equatorial regions4 ,the four inner moons are eclipsed at each revolution1 just at the hours when they are at their 8full40 ,the fifth alone attains the full phase4 ,contrary to the generally received opinion1 these bodies do not give to ,jupiter all the light which is supposed4 ,we might think1 in fact1 as has been so often stated1 that these five moons illuminate the nights five times better relatively than our single moon does in this respect1 and that they supplement in some measure the feebleness of the light received from the sun4 ,this result would be1 assuredly1 very agreeable1 but nature has not so arranged it4 ,the five satellites cover1 it is true1 an area of the sky greater than our moon1 but they reflect the light of a sun twenty-seven times smaller than ours2 indeed1 the total light reflected is only equal to a sixteenth of that of our full moon1 even supposing the soil of these satellites to be as white as it appears to be1 especially the fifth satellite4 ,jupiter appears to be a world still in process of formation1 which lately--some thousands of centuries ago--served as a sun to his own system of five or perhaps more worlds4 ,if the central body is not at present inhabited1 his satellites may be4 ,in this case1 the magnificence of the spectacle presented by ,jupiter himself to the inhabitants of the satellites is worthy of our attention4 ,seen from ,barnard's satellite1 ,jupiter's disk has a diameter of #dg1 or more than half the distance from the horizon to the zenith4 ,seen from the second satellite1 the ,jovian globe presents an immense disk of twenty degrees in diameter1 or #a1djj times larger than the full moon6 ,what a body6 ,what a picture1 with its belts1 its cloud motions1 and its glowing coloration1 seen from so near6 ,what a nocturnal sun6--still warm1 perhaps4 ,add to this the aspect of the satellites themselves seen from each other1 and you have a spectacle of which no terrestrial night can give an idea4 ,such is the world of ,jupiter from the double point of view of its vital organization and of the spectacle of external nature1 seen from this immense observatory4 ,the attraction of the planets has always played an important part in the motion of comets and the form of their orbits4 ,the enormous size of ,jupiter gives it more influence than any other planet1 and we are not surprised that it should have seriously interfered with some of the comets that belong to the ,solar ,system4 ,we have already seen that ,biela's comet was captured by ,jupiter1 and that it was probably dissolved into meteoric dust4 ,we show in the cut the orbits of eight others that circle around the sun1 but retreat no farther away than ,jupiter4 ,these are the orbits as now determined1 but they vary from age to age on account of disturbances of other planets4 ,but it is not likely that the comets themselves will ever escape from the control of ,jupiter4 ,illustration3 ,,orbits ,,of ,,nine ,,comets ,,captured ,,by ,,jupiter4 ,,chapter ,,xviii4 ,,saturn4 ,the system of ,jupiter is a simple system compared with that of ,saturn1 next in order4 ,for whereas ,jupiter has only five moons1 ,saturn has eight1 and1 in addition to these1 he has three wonderful rings4 ,neither rings nor moons can be seen without a telescope1 on account of ,saturn's great distance from us--more than three thousand times the distance of the moon1 or upwards of eight hundred millions of miles4 ,saturn's mean distance from the sun is eight hundred and seventy-six million seven hundred and sixty-seven thousand miles4 ,saturn does not equal his mighty brother ,jupiter in size1 though he comes near enough in this respect to be called often his 8twin0--just as that small pair of worlds1 ,venus and ,earth1 are called 8twins40 ,while ,jupiter is equal in size to over one thousand two hundred earths1 ,saturn is equal to about seven hundred earths4 ,and while ,jupiter is equal in weight to three hundred earths1 ,saturn is only equal in weight to ninety earths4 ,he appears to be made of very light materials--not more than three-quarters as dense as water4 ,this would show the present state of ,saturn to be very different from the present state of the earth4 ,we are under the same uncertainty in speaking of ,saturn as in speaking of ,jupiter4 ,like ,jupiter1 ,saturn is covered with dense masses of varying clouds1 occasionally opening and allowing the astronomer peeps into lower cloud-levels2 but rarely or never permitting the actual body of the planet to be seen4 ,the same perplexities also come in here1 to be answered much in the same manner4 ,we should certainly expect that in a vast globe like ,saturn the strong force of attraction would bind the whole into a dense solid mass2 instead of which1 ,saturn is about the least solid of all the planets4 ,he seems to be made up of a light1 watery substance1 surrounded by vapor4 ,illustration3 ,,saturn ,,and ,,the ,,earth--,,comparative ,,size4 ,one explanation can be offered4 ,what if the globe of ,saturn be still in a red-hot1 molten state1 keeping such water as would otherwise lie in oceans on his surface1 floating aloft in masses of steam1 the outer parts of which condense into clouds8 ,no one supposes that ,jupiter and ,saturn are in the same condition of fierce and tempestuous heat as the sun4 ,they may have been so once1 but they must now have cooled down very many stages from that condition4 ,though no longer1 however1 a mass of far-reaching flames and fiery cyclones1 the body of each may have only so far cooled as to have reached a stage of glowing molten red-heat1 keeping all water in the form of vapor1 and sending up strong rushes of burning air to cause the hurricanes which sweep to and fro the vast cloud-masses overhead4 ,and if this be the case1 then1 with ,saturn as with ,jupiter1 comes the question1 ,can ,saturn be inhabited8 ,and if--though we may not say it is impossible1 yet we feel it to be utterly unlikely--then again follows the question1 ,what if ,saturn's moons are inhabited8 ,telescopic observations tempt us to believe that there is on this planet a quantity of heat greater than that which results from its distance from the sun2 for the day-star as seen from ,saturn is1 as we have said1 ninety times smaller in surface1 and its heat and light are reduced in the same proportion4 ,water could only exist in the solid state of ice1 and the vapor of water could not be produced so as to form clouds similar to ours4 ,now1 meteorological variations are observed similar to those which we have noticed on ,jupiter1 but less intense4 ,facts1 then1 combine with theory to show us that the world of ,saturn is at a temperature at least as high as ours1 if not higher4 ,but the strangest feature of the ,saturnian calendar is1 unquestionably1 its being complicated1 not only with the fabulous number of #be1jfj days in a year1 but1 further1 with eight different kinds of months1 of which the length varies from #bb hours to #gi days--that is to say1 from about two ,saturnian days to #afg4 ,it is as if we had here eight moons revolving in eight different periods4 ,the inhabitants of such a world must assuredly differ strangely from us from all points of view4 ,the specific lightness of the ,saturnian substances and the density of the atmosphere will have conducted the vital organization in an extra-terrestrial direction1 and the manifestations of life will be produced and developed under unimaginable forms4 ,to suppose that there is nothing fixed1 that the planet itself is but a skeleton1 that the surface is liquid1 that the living beings are gelatinous--in a word1 that all is unstable--would be to surpass the limits of scientific induction4 ,the diameter of the largest moon is about half the diameter of the earth1 or much larger than ,mercury4 ,the four inner satellites are all nearer to ,saturn than our moon to us1 though the most distant of the eight is ten times as far away4 ,the inner moon takes less than twenty-three hours to travel round ,saturn1 and the outer one over seventy-nine days4 ,a great many charming descriptions have been worked up1 with ,saturn as with ,jupiter1 respecting the magnificent appearance of the eight radiant moons1 joined to the glorious shining of the rings1 as quite making up for the diminished light and heat of the sun4 ,but here again comes in the doubt1 whether really it is the moons who make up to ,saturn for lack of light1 or whether it is ,saturn who makes up to the moons for lack of light4 ,certainly1 ,saturn's cloudy covering would a little interfere with observations of the moons by any inhabitants of the solid body within--supposing there be any solid body at all4 ,and though it sounds very wonderful to have eight moons instead of one moon1 yet all the eight together give ,saturn only a very small part of the light which we receive from our one full moon--so much more dimly does the sun light them up at that enormous distance4 ,the same thing has been noticed with ,saturn as with ,jupiter--that he seems to shine more brightly than is to be expected in his position1 from mere reflection of the sun's rays4 ,a glowing body within1 sending a certain amount of added light through or between the masses of clouds1 would explain away this difficulty4 ,one more possible proof of ,saturn's half-liquid state is to be found in his occasional very odd changes of shape4 ,astronomers have been startled by a peculiar bulging out on one side1 taking off from his roundness1 and giving a square-shouldered aspect4 ,we may not say it is quite impossible that a solid globe should undergo such tremendous upheavals and outbursts as to raise a great portion of its surface five or six hundred miles above the usual level--the change being visible at a distance of eight hundred millions of miles4 ,but it would be easier to understand the possibility of such an event1 in the case of a liquid1 seething mass1 than in the case of a solid ball4 ,on the other hand this alteration of outline may be caused simply by a great upheaval not of the planet's surface1 but of the overhanging layers of clouds4 ,some such changes1 only much slighter1 have been remarked in ,jupiter4 ,and now as to the rings4 ,nothing like them is to be seen elsewhere in the ,solar ,system4 ,they are believed to be three in number2 though some would divide them into more than three4 ,passing completely round the whole body of ,saturn1 they rise1 one beyond another1 to a height of many thousands of miles4 ,the inner edge of the inner ring--an edge perhaps one hundred miles in thickness--is more than ten thousand miles from the surface of ,saturn or more strictly speaking1 from the outer surface of ,saturn's cloudy envelope4 ,a man standing exactly on the equator and looking up1 even if no clouds came between1 would scarcely be able to see such a slender dark line at such a height4 ,this dark1 transparent ring1 described sometimes as dusky1 sometimes as richly purple1 rises upwards to a height or breadth of nine thousand miles4 ,closely following it is a ring more brilliant than ,saturn himself1 over eighteen thousand miles in breadth4 ,when astronomers talk of the 8breadth0 of these rings1 it must be understood that they mean the width of the band measured upwards1 in a direction away from the planet4 ,beyond the broad1 bright ring is a gap of about one thousand seven hundred miles4 ,then follows the third ring1 ten thousand miles in breadth2 its outermost edge being at a height of more than forty-eight thousand miles from ,saturn4 ,the color of the third ring is grayish1 much like the gray markings often seen on ,saturn4 ,what would not be our admiration1 our astonishment1 our stupor perhaps1 if it were granted us to be transported there alive1 and1 among all these extra-terrestrial spectacles1 to contemplate the strange aspect of the rings1 which stretch across the sky like a bridge suspended in the heights of the firmament6 ,suppose we lived on the ,saturnian equator itself1 these rings would appear to us as a thin line drawn across the sky above our heads1 and passing exactly through the zenith1 rising from the east and increasing in width1 then descending to the west and diminishing according to perspective4 ,only there have we the rings precisely in the zenith4 ,the traveler who journeys from the equator towards either pole leaves the plane of the rings1 and these sink imperceptibly1 at the same time that the two extremities cease to appear diametrically opposite1 and by degrees approach each other4 ,what an amazing effect would be produced by this gigantic arch1 which springs from the horizon and spans the sky6 ,the celestial arch diminishes in height as we approach the pole4 ,when we reach the sixty-third degree of latitude the summit of the arch has descended to the level of our horizon and the marvelous system disappears from the sky2 so that the inhabitants of those regions know nothing of it1 and find themselves in a less favorable position to study their own world than we1 who are nearly #hjj1jjj1jjj miles distant4 ,during one-half of the ,saturnian year the rings afford an admirable moonlight on one hemisphere of the planet1 and during the other half they illuminate the other hemisphere2 but there is always a half-year without 8ringlight10 since the sun illuminates but one face at a time4 ,notwithstanding their volume and number1 the satellites do not give as much nocturnal light as might be supposed2 for they receive1 on an equal surface1 only the ninetieth part of the solar light which our moon receives4 ,all the ,saturnian satellites which can be at the same time above the horizon and as near as possible to the full phase do not afford more than the hundredth part of our lunar light4 ,but the result may be nearly the same1 for the optic nerve of the ,saturnians may be ninety times more sensitive than ours4 ,but there are further strange features in this system4 ,the rings are so wide that their shadow extends over the greater part of the mean latitudes4 ,during fifteen years the sun is to the south of the rings1 and for fifteen years it is to the north4 ,the countries of ,saturn's world which have the latitude of ,paris endure this shadow for more than five years4 ,at the equator the eclipse is shorter1 and is only renewed every fifteen years2 but there are every night1 so to say1 eclipses of the ,saturnian moons by the rings and by themselves4 ,in the circumpolar regions the day-star is never eclipsed by the rings2 but the satellites revolve in a spiral1 describing fantastic rounds1 and the sun himself disappears at the pole during a long night of fifteen years4 ,at one time it was supposed that the rings were solid1 but they are now believed to consist of countless myriads of meteorites1 each whirling in its own appointed pathway round the monster planet4 ,illustration3 ,,ideal ,,view ,,of ,,saturn',s ,,rings ,,and ,,satellites ,,from ,,the ,,planet4 ,as already said--leaving out of the question the cloudy atmosphere--a man standing on the equator would see nothing of the rings4 ,a man standing at the north pole or the south pole of ,saturn could see nothing either1 since the rings would all lie below his horizon4 ,but if he traveled southward from the north pole1 or northward from the south pole1 towards the equator1 he would in time see the ringed arch appearing above the horizon1 rising higher and growing wider with every mile of his journey2 and when he was in a position to view the whole broad expanse1 the transparent half-dark belt below1 the wide radiant band rising upwards over that1 and the grayish border surmounting all1 he would truly have a magnificent spectacle before him4 ,this magnificent spectacle is1 however1 by no means always visible1 even from those parts of ,saturn where alone it ever can be seen4 ,the rings shine merely by reflected sunlight4 ,necessarily1 therefore1 while the sunbeams make one side bright the other side is dark2 and not only this1 but the rings throw broad and heavy shadows upon ,saturn in the direction away from the sunlight4 ,in the daytime they probably give out a faint shining1 something like our own moon when seen in sunlight4 ,during the summer nights they shine1 no doubt1 very beautifully4 ,during the winter nights it so happens that their bright side is turned away2 and not only that1 but during the winter days the rings1 while giving no light themselves to the wintry hemisphere of ,saturn1 completely hide the sun4 ,when it is remembered that ,saturn's winter--that is1 the winter of each hemisphere in turn--lasts during fifteen of our years2 and when we hear of total eclipses of the sun lasting unbroken through eight years of such a winter1 with not even bright rings to make up for his absence1 we can not think of ,saturn as a tempting residence4 ,the sun gives ,saturn at his best only about one-ninetieth of the heat and light that he gives to our earth2 but to be deprived of even that little for eight years at a time1 does indeed sound somewhat melancholy4 ,looking now at the other side of the question1 the possible inhabitants of the moons1 especially those near at hand1 would have splendid views of ,saturn and his rings in all their varying phases4 ,for ,saturn is a beautiful globe1 wrapped in his changeful envelope of clouds1 which1 seen through a telescope1 are lit up often with rainbow tints of blue and gold2 a creamy white belt lying usually on the equator2 while around extend the purple and shining and gray rings1 sometimes rivaling in bright colors ,saturn himself4 ,we are compelled to assume that the continuous appearance of the rings is not due to real continuity of substance1 but that they are composed of flights of disconnected satellites1 so small and so closely packed that1 at the immense distance to which ,saturn is removed1 they appear to form a continuous mass4 ,there are analogous instances in the ,solar ,system4 ,in the zone of asteroids we have an undoubted instance of a flight of disconnected bodies traveling in a ring about a central attracting mass4 ,the existence of zones of meteorites traveling around the sun has long been accepted as the only probable explanation of the periodic returns of meteoric showers4 ,again1 the singular phenomenon called the ,zodiacal ,light is1 in all probability1 caused by a ring of minute cosmical bodies surrounding the sun4 ,in the ,milky ,way and in the ring-nebul we have other illustrations of similar arrangements in nature1 belonging1 however1 to orders immeasurably vaster than any within the ,solar ,system4 ,the moons of ,saturn do not1 like those of ,jupiter1 travel in one plane4 ,,chapter ,,xix4 ,,uranus ,,and ,,neptune4 ,till the year #agha1 ,saturn was believed to be the outermost planet of the ,solar ,system1 and nobody suspected the fact of two great1 lonely brother-planets wandering around the same sun at vast distances beyond1--,uranus1 nine hundred millions of miles from ,saturn2 ,neptune1 nine hundred millions of miles from ,uranus4 ,no wonder they remained long undiscovered4 ,uranus can sometimes be seen by the unaided eye as a dim star of the sixth magnitude4 ,and when he was known for a planet1 it was found that he had been often so seen and noted4 ,again and again he had been taken for a fixed star1 and as he moved on1 disappearing from that particular spot1 it was supposed that the star had vanished4 ,one night1 ,march #ac1 #agha1 when ,william ,herschel was busily exploring the heavens with a powerful telescope1 he noticed something which he took for a comet without a tail4 ,he saw it was no mere point of light like the stars1 but had a tiny round disk or face1 which could be magnified4 ,so he watched it carefully1 and found in the course of a few nights that it moved--very slowly1 certainly2 but still it did move4 ,further watching and calculation made it clear that1 though the newly-found heavenly body was at a very great distance from the sun1 yet it was moving slowly in an orbit round the sun4 ,then it was known to be a planet1 and another member of the ,solar ,system4 ,from that day the reputation of ,herschel rapidly increased4 ,king ,george ,,iii1 who loved the sciences and patronized them1 had the astronomer presented to him2 charmed with the simple and modest account of his efforts and his labors1 he secured him a life pension and a residence at ,slough1 in the neighborhood of ,windsor ,castle4 ,his sister ,caroline assisted him as secretary1 copied all his observations1 and made all his calculations2 the king gave him the title and salary of assistant astronomer4 ,before long the observatory at ,slough surpassed in celebrity the principal observatories of ,europe2 we may say that1 in the whole world1 this is the place where the most discoveries have been made4 ,astronomers soon applied themselves to the observation of the new body4 ,they supposed that this 8comet0 would describe1 as usually happens1 a very elongated ellipse1 and that it would approach considerably to the sun at its perihelion4 ,but all the calculations made on this supposition had to be constantly recommenced4 ,they could never succeed in representing all its positions1 although the star moved very slowly3 the observations of one month would utterly upset the calculations of the preceding month4 ,several months elapsed without a suspicion that a veritable planet was under observation1 and it was not till after recognizing that all the imaginary orbits for the supposed comet were contradicted by the observations1 and that it had probably a circular orbit much farther from the sun than ,saturn1 till then the frontier of the system1 that astronomers came to consider it as a planet4 ,still1 this was at first but a provisional consent4 ,illustration3 ,,prominent ,,astronomers ,,of ,,former ,,times4 ,tycho ,brahe1 ,hipparchos1 ,galilei1 ,newton1 ,kepler1 ,kant1 ,kopernikus1 ,laplace4 ,it was1 in fact1 more difficult than we may think to increase without scruple the family of the sun4 ,indeed1 for reasons of expediency this idea was opposed4 ,ancient ideas are tyrannical4 ,men had so long been accustomed to consider old ,saturn as the guardian of the frontiers1 that it required a rare boldness of spirit to decide on extending these frontiers and marking them by a new world4 ,william ,herschel proposed the name of ,georgium ,sidus 8the ,star of ,george10 just as ,galileo had given the name of 8,medicean stars0 to the satellites of ,jupiter discovered by him1 and as ,horace had said ,julium ,sidus4 ,others proposed the name of ,neptune1 in order to maintain the mythological character1 and to give to the new body the trident of the ,english maritime power2 others1 ,uranus1 the most ancient deity of all1 and the father of ,saturn1 to whom reparation was due for so many centuries of neglect4 ,lalande proposed the name of ,herschel1 to immortalize the name of its discoverer4 ,these last two denominations prevailed4 ,for a long time the planet bore the name of ,herschel2 but custom has since declared for the mythological appellation1 and ,jupiter1 ,saturn1 and ,uranus succeed each other in order of descent--son1 father1 and grandfather4 ,the discovery of ,uranus extended the radius of the ,solar ,system from #hhe1jjj1jjj to #a1gfe1jjj1jjj of miles4 ,the apparent brightness of this planet is that of a star of the sixth magnitude2 observers whose sight is very piercing may succeed in recognizing it with the naked eye when they know where to look for it4 ,uranus moves slowly from west to east1 and takes no less than eighty-four years to make the complete circuit of the sky4 ,in its annual motion round the sun the earth passes between the sun and ,uranus every #cfi days--that is to say1 once in a year and four days4 ,it is at these times that this planet crosses the meridian at midnight4 ,we can observe it in the evening sky for about six months of every year4 ,everybody supposed that now1 at least1 the outermost member of all was discovered4 ,but a very strange and remarkable thing happened4 ,astronomers know with great exactness the paths of the planets in the heavens4 ,they can tell1 years beforehand1 precisely what spot in space will be filled at any particular time by any particular planet4 ,i am speaking now of their movements round the sun and in the ,solar ,system--not of the movements of the whole family with the sun1 about which little is yet known4 ,each planet has its own particular pathway2 its own particular distance from the sun1 varying at each part of its pathway2 its own particular speed in traveling round the sun1 changing constantly from faster to slower or slower to faster1 according to its distance from the sun1 and according to the pull backwards or forwards of our neighboring planets in front or in rear4 ,for as the orbits of all the planets are ovals1 with the sun not in the middle1 but somewhat to one side of the middle1 it follows that all the planets1 in the course of their years1 are sometimes nearer to and sometimes farther from the sun4 ,the astronomers of the present day understand this well1 and can describe with exactness the pathway of each planet4 ,this knowledge does not come merely from watching one year how the planets travel1 and remembering for another year1 but is much more a matter of close and difficult calculation4 ,many things have to be considered1 such as the planet's distance from the sun1 the sun's power of attraction1 the planet's speed1 the nearness and weight of other neighboring planets4 ,all these questions were gone into1 and astronomers sketched out the pathway in the heavens which they expected ,uranus to follow4 ,he would move in such and such an orbit1 at such and such distances from the sun1 and at such and such rates of speed4 ,but ,uranus would not keep to these rules4 ,he quite discomfited the astronomers4 ,sometimes he went fast1 when1 according to their notions1 he ought to have gone more slowly2 and sometimes he went slowly1 when they would have looked for him to go more fast1 and the line of his orbit was quite outside the line of the orbit which they had laid down4 ,he was altogether a perplexing acquaintance1 and difficult to understand4 ,however1 astronomers felt sure of their rules and modes of calculation1 often before tested1 and not found to fail4 ,they made a guess at an explanation4 ,what if there were yet another planet beyond ,uranus1 disturbing his motions--now drawing him on1 now dragging him back1 now so far balancing the sun's attraction by pulling in the opposite direction as to increase the distance of ,uranus from the sun8 ,it might be so4 ,but who could prove it8 ,hundreds of years might pass before any astronomer1 in his star-gazing1 should happen to light upon such a dim and distant world4 ,nay1 the supposed planet might be1 like ,uranus1 actually seen1 and only be mistaken for a 8variable star10 shining but to disappear4 ,there the matter seemed likely to rest4 ,there the matter probably would have rested for a good while1 had not two men set themselves to conquer the difficulty4 ,one was a young ,englishman1 a student of ,cambridge1 ,john ,couch ,adams2 the other1 a young ,frenchman1 ,urbain ,jean ,joseph ,leverrier1--both being astronomers4 ,each worked independently of the other1 neither knowing of the other's toil4 ,the task which they had undertaken was no light one--that of reaching out into the unknown depths of space to find an unknown planet4 ,each of these silent searchers into the sky-depths calculated what the orbit and speed of ,uranus would be1 without the presence of another disturbing planet beyond4 ,each examined what the amount of disturbance was1 and considered the degree of attraction needful to produce that disturbance1 together with the direction from which it had come4 ,each1 in short1 gradually worked his way through calculations far too deep and difficult for ordinary minds to grasp1 till he had found just that spot in the heavens where a planet ought to be1 to cause1 according to known laws1 just such an effect upon ,uranus as had been observed4 ,adams finished his calculation first1 and sent the result to two different observatories4 ,unfortunately1 his report was not eagerly taken up4 ,it was1 in fact1 hardly believed4 ,leverrier finished his calculation also1 and sent the result to the ,berlin ,observatory4 ,the planet was actually seen in ,england first1 but the discovery was actually made known from ,berlin first4 ,the young ,englishman had been beforehand1 but the young ,frenchman gained foremost honor4 ,it was on the #bc;d of ,september1 #ahdf1 that ,leverrier's letter reached the ,berlin astronomers4 ,the sky that night was clear1 and we can easily understand with what anxiety ,dr4 ,galle directed his telescope to the heavens4 ,the instrument was pointed in accordance with ,leverrier's instructions4 ,the field of view showed1 as does every part of the heavens1 a multitude of stars4 ,one of these was really the planet4 ,the new chart--prepared by the ,berlin ,academy of ,sciences1 upon which the place of every star1 down even to those of the tenth magnitude1 was engraved--was unrolled1 and1 star by star1 the heavens were compared with the chart4 ,as the process of identification went on1 one object after another was found in the heavens as engraved on the chart1 and was of course rejected4 ,at length a star of the eighth magnitude--a brilliant object--was brought into review4 ,the map was examined1 but there was no star there4 ,this object could not have been in its present place when the map was formed4 ,the object was therefore a wanderer--a planet4 ,yet it is necessary to be excessively cautious in such a matter4 ,many possibilities had to be guarded against4 ,it was1 for instance1 possible that the object was really a star which1 by some mischance1 eluded the careful eye of the astronomer who constructed the map4 ,it was even possible that the star might be one of the large class of variables which alternate in brightness1 and it might have been conceivable that it was too faint to be seen when the chart was made4 ,even if neither of these explanations would answer1 it was still necessary to show that the object was now moving1 and moving with that particular velocity and in that particular direction which the theory of ,leverrier indicated4 ,the lapse of a single day was sufficient to dissipate all doubts4 ,the next night the object was again observed4 ,it had moved1 and when its motion was measured it was found to accord precisely with what ,leverrier had foretold4 ,indeed1 as if no circumstance in the confirmation should be wanting1 it was ascertained that the diameter of the planet1 as measured by the micrometers at ,berlin1 was practically coincident with that anticipated by ,leverrier4 ,the world speedily rang with the news of this splendid achievement4 ,instantly the name of ,leverrier rose to a pinnacle hardly surpassed by that of any astronomer of any age or country4 ,for a moment it seemed as if the ,french nation were to enjoy the undivided honor of this splendid triumph4 ,but in the midst of the pans of triumph with which the enthusiastic ,french nation hailed the discovery of ,leverrier1 there appeared a letter from ,sir ,john ,herschel in the ,athenum for #c;d ,october1 #ahdf1 in which he announced the researches made by ,adams1 and claimed for him a participation in the glory of the discovery4 ,subsequent inquiry has shown that this claim was a just one1 and it is now universally admitted by all independent authorities4 ,this1 however1 was of slight comparative importance4 ,the truly wonderful part of the matter was1 that these two men could have so reasoned that1 from the movements of one lately-discovered planet1 they could point out the exact spot where a yet more distant planet ought to be1 and that close to this very spot the planet was found4 ,for when1 both in ,england and in ,germany1 powerful telescopes were pointed in the direction named--there the planet was4 ,no doubt about the matter4 ,not a star1 but a real new planet in the far distance1 wandering slowly round the sun4 ,here we have the discovery of ,neptune in its simple grandeur4 ,this discovery is splendid1 and of the highest order from a philosophical point of view1 for it proves the security and the precision of the data of modern astronomy4 ,considered from the point of view of practical astronomy1 it was but a simple exercise of calculation1 and the most eminent astronomers saw in it nothing else6 ,it was only after its verification1 its public demonstration--it was only after the visual discovery of ,neptune--that they had their eyes opened1 and felt for a moment the dizziness of the infinite in view of the horizon revealed by the ,neptunian perspective4 ,the author of the calculation himself1 the transcendent mathematician1 did not even give himself the trouble to take a telescope and look at the sky to see whether a planet was really there6 ,i even believe that he never saw it4 ,for him1 however1 then and always1 to the end of his life1 astronomy was entirely inclosed in formul--the stars were but centers of force4 ,very often ,i submitted to him the doubts of an anxious mind on the great problems of infinitude3 ,i asked him if he thought that the other planets might be inhabited like ours1 what might be especially the strange vital conditions of a world separated from the sun by the distance of ,neptune1 what might be the retinue of innumerable suns scattered in immensity1 what astonishing colored lights the double stars should shed on the unknown planets which gravitate in these distant systems4 ,his replies always showed me that these questions had no interest for him1 and that1 in his opinion1 the essential knowledge of the universe consisted in equations1 formul1 and logarithmic series having for their object the mathematical theory of velocities and forces4 ,but it is not the less surprising that he had not the curiosity to verify the position of his planet1 which would have been easy1 since it shows a planetary disk2 and1 besides1 he might have had the aid of a chart1 because he had only to ask for these charts from the ,berlin ,observatory1 where they had just been finished and published4 ,it is not the less surprising that ,arago1 who was more of a physicist than a mathematician1 more of a naturalist than a calculator1 and whose mind had so remarkable a synthetical character1 had not himself directed one of the telescopes of the observatory towards this point of the sky1 and that no other ,french astronomer had this idea4 ,but what surprises us still more is to know that nearly a year before1 in ,october1 #ahde1 a young student of the ,university of ,cambridge1 ,mr4 ,adams1 had sought the solution of the same problem1 obtained the same results1 and communicated these results to the director of the ,greenwich ,observatory1 and that the astronomer to whom these results were confided had said nothing1 and had not himself searched in the sky for the optical verification of his compatriot's solution6 ,this was indeed a triumph of human intellect4 ,yet it is no matter for human pride1 but rather of thankfulness to ,god1 who gave to man this marvelous reasoning power4 ,and the very delight we have in such a success may humble us in the recollection of the vast amount lying beyond of the utterly unknown4 ,but while the rare mind of a ,newton could meekly realize the littleness of all he knew1 lesser minds are very apt to be puffed up with the thought of what the human intellect can accomplish4 ,perhaps the chief feeling of lawful satisfaction in this particular discovery arises from the fact that it gives marked and strong proof of the truth of our present astronomical system and beliefs4 ,many mistakes may be made1 and much has often to be unlearned4 ,nevertheless1 if the general principles of modern astronomy were wrong1 if the commonly-received facts were a delusion1 such complete success could not have attended so delicate and difficult a calculation4 ,we do not know much about these two outer planets1 owing to their enormous distance from us4 ,uranus is in size equal to seventy-four earths1 and ,neptune is in size equal to one hundred and five earths4 ,both these planets are formed of somewhat heavier materials than ,saturn1 being about as dense as water4 ,the size of the sun as seen from ,uranus is about one three-hundred-and-ninetieth part of the size of the sun we see4 ,to ,neptune he shows a disk only one nine-hundredth part of the size of that visible to us--no disk at all1 in fact1 but only starlike brilliancy4 ,the ,uranian year lasts about eighty-four of our years2 and this1 with a very sloping axis1 must cause most long and dreary winters1 the tiny sun being hidden from parts of the planet during half an earthly life-time4 ,uranus has at least four moons1 traveling in very different planes from the plane of the ecliptic4 ,once it was thought that he had eight1 but astronomers have since searched in vain for the other four1 believed for a while to exist4 ,neptune has one moon1 and may possess others not yet discovered4 ,sir ,henry ,holland1 the celebrated physician1 and a devoted student of astronomy1 has left on record an incident of his life connected with the planet ,neptune of singular interest4 ,i give it here1 and in his own words1 because it is scarcely likely otherwise to fall under the notice of astronomical readers4 ,after stating that his interest in astronomy had led him to take advantage of all opportunities of visiting foreign observatories1 he says3 8,some of these opportunities1 indeed1 arising out of my visits to observatories both in ,europe and ,america1 have been remarkable enough to warrant a more particular mention of them4 ,that which most strongly clings to my memory is an evening ,i passed with ,encke and ,galle in the observatory at ,berlin1 some ten or twelve days after the discovery of the planet ,neptune on this very spot2 and when every night's observations of its motions had still an especial value in denoting the elements of its orbit4 ,i had casually heard of the discovery at ,bremen1 and lost no time in hurrying on to ,berlin4 ,the night in question was one of floating clouds1 gradually growing into cumuli2 and hour after hour passed away without sight of the planet which had just come to our knowledge by so wonderful a method of predictive research4 ,frustrated in this main point1 it was some compensation to stay and converse with ,encke in his own observatory1 one signalized by so many discoveries1 the stillness and darkness of the place broken only by the solemn ticking of the astronomical clock1 which1 as the unfailing interpreter of the celestial times and motions1 has a sort of living existence to the astronomer4 ,among other things discussed1 while thus sitting together in a sort of tremulous impatience1 was the name to be given to the new planet4 ,encke told me he had thought of #8,vulcan1' but deemed it right to remit the choice to ,leverrier1 then supposed to be the sole indicator of the planet and its place in the heavens2 adding that he expected ,leverrier's answer by the first post4 ,not an hour had elapsed before a knock at the door of the observatory announced the letter expected4 ,encke read it aloud2 and1 coming to the passage where ,leverrier proposed the name of #8,neptune1' exclaimed1 #8,so lass den ,namen ,neptun sein4' ,it was a midnight scene not easily to be forgotten4 ,a royal baptism1 with its long array of titles1 would ill compare with this simple naming of the remote and solitary planet thus wonderfully discovered4 ,there is no place1 indeed1 where the grandeur and wild ambitions of the world are so thoroughly rebuked and dwarfed into littleness as in the astronomical observatory4 ,as a practical illustration of this remark1 ,i would add that my own knowledge of astronomers--those who have worked themselves with the telescope--has shown them to be generally men of tranquil temperament1 and less disturbed than others by worldly affairs1 or by the quarrels incident even to scientific research40 ,the same reasoning which has been used in reference to ,jupiter and his moons1 and to ,saturn and his moons1 might perhaps be applied also to ,uranus and ,neptune and their moons4 ,we know too little yet of their condition to venture far in such speculations4 ,still1 taking the matter as a whole1 there seem many reasons to incline us to the idea that each of the four greater outside planets may be a kind of secondary half-cooled sun to his satellites1 helping to make up to them for the small amount of light and heat which they can obtain from the far-off sun4 ,,chapter ,,xx4 ,,comets ,,and ,,meteorites4 ,a curious discovery has been lately made4 ,it is that some sort of mysterious tie seems to exist between comets and meteorites4 ,for a long while this was never suspected4 ,how should it be8 ,the comets1 so large1 so airy1 so light2 the meteorites1 so small1 so solid1 so heavy1--how could it possibly be supposed that the one had anything to do with the other8 ,but supposings often have to give in to facts4 ,astronomers are gradually becoming convinced that there certainly is a connection between the two4 ,strange to say1 comets and meteorites occupy--sometimes1 at least--the very same pathways in the heavens1 the very same orbits round the sun4 ,a certain number of meteorite systems are now pretty well known to astronomers as regularly met by our earth at certain points in her yearly journey4 ,some of these systems or rings have each a comet belonging to it--not merely journeying near1 but actually in its midst1 on the same orbit4 ,perhaps it would be more correct to say that the meteorites belong to the comet1 than that the comet belongs to the meteorites4 ,we tread here on uncertain ground2 for whether the meteorites spring from the comet1 or whether the comet springs from the meteorites1 or whether each has been brought into existence independently of the other1 no one can at present say4 ,though it is out of our power to explain the kind of connection1 yet a connection there plainly is4 ,so many instances are now known of a comet and a meteorite ring traveling together that it is doubtful whether any such ring could be found without a comet in its midst4 ,by and by the doubt may spring up whether there ever exists a comet without a train of meteorites following him4 ,among the many different meteorite rings which are known1 two of the most important are the so-called ,august and ,november systems4 ,of these two1 the ,november system must claim our chief attention4 ,not that we are at all sure of these being the most important meteorite rings in the ,solar ,system4 ,on the contrary1 as regards the ,november ring1 we have some reason to think that matters may lie just the other way4 ,the comet belonging to the ,november system is a small one--quite an insignificant little comet--only visible through a telescope4 ,we do not1 of course1 know positively that larger comets and greater meteorite systems generally go together1 but1 to say the least1 it seems likely4 ,and if the greatness of a ring can at all be judged of by the size of its comet1 then the ,november system must be a third-rate specimen of its kind4 ,it is of particular importance to us1 merely because it happens to be the one into which our earth plunges most deeply1 and which we therefore see and know the best4 ,the ,august ring is1 on the contrary1 connected with a magnificent comet1 and may be a far grander system4 ,but our pathway does not lead us into the midst of the ,august meteors as into those of ,november4 ,we pass1 seemingly1 through its outskirts4 ,the meteorites of the ,november system are very small4 ,they are believed to weigh commonly only a few grains each4 ,if they were larger and heavier1 some of them would fall to earth as aerolites1 not more than half-burnt in their rush through the atmosphere4 ,but this they are never found to do4 ,there are known meteorite systems1 which our earth merely touches or grazes in passing1 from which drop aerolites of a very different description--large1 heavy1 solid masses4 ,it is well for us that we do not plunge into the midst of any such ring1 or we might find our air1 after all1 a poor protection4 ,the last grand display of the ,november system of meteorites took place in the years #ahff to #ahfi1 being continued more or less during three or four ,novembers following4 ,the next grand display will occur in the year #ahii4 ,for this system--,leonides1 as it is called1 because the falling-stars in this display seem all to shoot towards us from a spot in the constellation ,leo--seems to have a 8time0 or 8year0 of thirty-three and a quarter earthly years4 ,the shape of its orbit is a very long ellipse1 near one end of which is the sun1 while the other end is believed to reach farther away than the orbit of ,uranus4 ,a great deal of curiosity has been felt about the actual length and breadth and depth of the stream of meteorites through which our solid earth has so often plowed her way4 ,during many hours at a time1 lookers-on have watched the magnificent display of heavenly fireworks1--not a mere shooting-star here and there1 as on common nights1 but radiant meteors1 flashing and dying by thousands through the sky4 ,in #ahff no less than eight thousand meteors1 in two hours and a quarter1 were counted from the ,greenwich ,observatory in ,england4 ,a natural wonder sprang up in many minds as to the extent of the ring from which they fell4 ,for not in one night only1 but in several nights during three or four years1 and that not once only but once in every thirty-three years1 thousands and tens of thousands appear to have been stolen by our earth from the meteorite-ring1 never again to be restored4 ,yet each time we touch the ring1 we find the abundance of little meteorites in nowise seemingly lessened4 ,when speaking of a 8ring0 of meteorites1 it must not be supposed that necessarily the meteorites form a whole unbroken ring all round the long oval orbit4 ,there may be no breaks4 ,there may be a more or less thin scattering throughout the entire length of the pathway4 ,but the meteorites certainly seem to cluster far more densely in some parts of the orbit than in other parts1 and it was about the size of the densest cluster that so much curiosity was felt4 ,little can be positively known1 though it is very certain that the cluster must be enormous in extent4 ,three or four years running1 as our earth1 after journeying the whole way round the sun1 came again to that point in her orbit where she passes through the orbit of the ,leonides1 she found the thick stream of meteorites still pouring on1 though each year lessening in amount4 ,taking into account this fact1 and also the numbers that were seen to fall night after night1 and also the speed of our earth1 a 8rough estimate0 was formed4 ,the length of this dense cluster is supposed to reach to many hundreds of millions of miles4 ,the thickness or depth of the stream is calculated to be in parts over five hundred thousand miles1 and the breadth about ten times as much as the depth4 ,each meteorite is probably at a considerable distance from his neighbor2 but the whole mass of them1 when in the near neighborhood of the sun1 must form a magnificent sight4 ,and if this be only a third-rate system1 what must a first-rate system be like8 ,and how many such systems are there throughout the sun's wide domains8 ,the most powerful telescope gives us no hint of the existence of these rings till we find ourselves in their midst4 ,it may be that they are numbered by thousands1 even by millions4 ,the whole of the ,solar ,system--nay1 the very depths of space beyond--may1 for aught we know1 be crowded with meteorite systems4 ,every comet may have his stream of meteorites following him4 ,but though the comet is visible to us1 the meteorites are not4 ,billions upon billions of them may be ever rushing round our sun1 entirely beyond our ken1 till one or another straggler touches our atmosphere to flash and die as a 8shooting star0 in our sight4 ,we have1 and with our present powers we can have1 no certainty as to all this4 ,but ,i may quote here the illustration of a well-known astronomical writer on the subject4 ,suppose a blind man were walking out of doors along a high road1 and during the course of a few miles were to feel rain falling constantly upon him4 ,would it be reasonable on his part1 if he concluded that a small shower of rain had accompanied him along the road as he moved1 but that fine weather certainly existed on either side of the road8 ,on the contrary1 he might be sure that the drops which he felt1 were but a few among millions falling all together4 ,or1 look at the raindrops on your window some dull day at home4 ,count how many there are8 ,could you1 with any show of common sense1 decide that those raindrops1 and those alone1 had fallen that day8 ,so1 when we find these showers of meteorites falling to earth1 we may safely conclude that1 for every one which touches our atmosphere1 myriads rush elsewhere in space1 never coming near us4 ,,chapter ,,xxi4 ,,more ,,about ,,comets ,,and ,,meteorites4 ,the three prominent features of comets--a head1 nucleus1 and tail--are seen only in particular instances4 ,the great majority appear as faint globular masses of vapor1 with little or no central condensation1 and without tails4 ,on the other hand1 some have a strongly-defined nucleus1 which shines with a light as vivacious as that of the planets1 so as to be even visible in the daytime4 ,this was the case with one seen at ,rome soon after the assassination of ,julius ,csar1 believed by the populace to be the soul of the dictator translated to the skies4 ,the first comet of the year #addb was also so brilliant1 that the light of the sun at noon1 at the end of ,march1 did not prevent it from being seen2 and the second1 which appeared in the summer1 was visible for a considerable time before sunset4 ,in #aecb1 the people of ,milan were alarmed by the appearance of a star in the broad daylight2 and as ,venus was not then in a position to be visible1 the object is inferred to have been a comet4 ,tycho ,brahe discovered the comet of #aegg1 from his observatory in the isle of ,huene1 in the sound1 before sunset2 and ,chizeaux saw the comet of #agdd1 at one o'clock in the afternoon1 without a telescope4 ,the comet of #ahdc1 already referred to in a previous chapter1 was distinctly seen at noon by many persons in the streets of ,bologna without the aid of glasses4 ,the nucleus is generally of small size1 but the surrounding nebulosity1 which forms the head1 is often of immense extent2 and the hazy envelope1 the 8horrid hair0 of poetry1 is sometimes seen separated from it by a dark space1 encircling it like a ring4 ,this was the aspect of the comet of #ahaa4 ,the entire diameter of the head measured #a1bej1jjj miles1 and hence its bulk was nearly three times that of the sun1 and four million times that of the earth4 ,but such extraordinary dimensions are quite exceptional4 ,illustration3 ,,the ,,great ,,comet ,,of #ahaa4 ,popular impressions respecting the supposed terrestrial effects of the comet of #ahaa--;a fine object in the autumn of that year1 long remembered by many--are on record4 ,it was gravely noted1 that wasps were very few in number2 that flies became blind1 and disappeared early2 and that twins were born more frequently than usual4 ,the season was remarkable for its bountiful harvest and abundant vintage4 ,grapes1 figs1 melons1 and other fruits1 were not only produced in extraordinary quantity1 but of delicious flavor1 so that 8comet wines0 had distinct bins allotted to them in the cellars of merchants1 and were sold at high prices4 ,there is1 however1 no fact better attested1 by a comparison of observations1 than that comets have no influence whatever in heightening or depressing the temperature of the seasons4 ,the fine fruits and ample harvest of the year in question were1 therefore1 coincidences merely with the celestial phenomenon1 without the slightest physical connection with it4 ,though the advanced civilization of recent times has led to juster views of cometary apparitions than to regard them as divinely-appointed omens of terrestrial calamity1 yet society is apt to be nervous respecting these bodies1 as likely to cause some great natural convulsion by collision with our globe4 ,the great comet1 which in #afhb received first the name of ,halley's comet1 appeared last in #ahce1 his return having been foretold within three days of its actually taking place4 ,for ,halley's comet is a member of the ,solar ,system1 having a yearly journey of seventy-six earthly years4 ,he journeys nearer the sun than ,venus1 and travels farther away than ,neptune4 ,in the years #aheh1 #ahfa1 and #ahfb1 three more comets appeared1 all visible without the help of a telescope4 ,of these three1 ,donati's comet1 in #aheh1 was far superior to the rest4 ,this fine object was first discovered on the #b;d of ,june by ,dr4 ,donati1 at ,florence4 ,it appeared at first as a faint nebulous patch of light1 without any remarkable condensation2 and as its motion towards the sun at that time was slow1 it was not till the beginning of ,september that it became visible to the naked eye4 ,a short tail was then seen on the side opposite to the sun4 ,illustration3 ,,donati',s ,,comet1 #aheh4 ,the development was afterwards rapid1 and the comet became equally interesting to the professional astronomer and to the unlearned gazer4 ,in the first week of ,october the tail attained its greatest length1 #cf4 ,at this time the tail was sensibly curved1 and had the appearance of a large ostrich-feather when waved gently in the hand4 ,at the latter end of ,october the comet was lost in the evening twilight4 ,its nearest approach to the earth was about equal to half the distance of the earth from the sun1 and the nearest approach to ,venus was about one-ninth part of that distance4 ,an elliptical orbit1 with a periodic time of more than #b1jjj years1 has been assigned to our late visitor4 ,it was a singular fact about this comet that at one time the star ,arcturus could be seen shining through the densest portion of the tail1 close to the nucleus4 ,now1 although the faintest cloud-wreath of earth would dim1 if not hide1 this star1 yet the tail of the great comet was of so transparent a nature that ,arcturus shone undimmed1 as if no veil had come between4 ,the exceedingly slight and airy texture of a comet's tail could hardly be more plainly shown4 ,it was this gauzy appendage to a little nucleus which men once thought could destroy our solid earth at a single blow6 ,these cometary trains generally appear straight1 or at least1 by the effect of perspective1 they seem to be directed along the arcs of great circles of the celestial sphere4 ,some are recorded1 however1 which presented a different appearance4 ,thus1 in #afhi1 a comet was seen whose tail1 according to the historians1 was curved like a ,turkish saber4 ,this tail had a total length of #fh4 ,it was the same with the beautiful comet of ,donati1 which we admired in #aheh1 and of which the tail had a very decided curvature4 ,a comet can only be observed in the sky for a limited time4 ,we perceive it at first in a region where nothing was visible on preceding days4 ,the next day1 the third day1 we see it again2 but it has changed its place considerably among the constellations4 ,we can thus follow it in the sky for a certain number of days1 often during several months2 then we cease to perceive it4 ,often the comet is lost to view because it approaches the sun1 and the vivid light of that body hides it completely2 but soon we observe it again on the other side of the sun1 and it is not till some time afterwards that it definitely disappears4 ,some have been visible at noonday1 quite near the sun1 like that of #ahhb1 on ,september #agth4 ,yet1 while taking care not to overrate1 we must not underrate4 ,true1 the comets are delicate and slight in structure4 ,one comet1 in #aggj1 wandered into the very midst of ,jupiter's moons1 and so small was its weight that it had no power whatever1 so far as has been detected1 to disturb the said moons in their orbits4 ,jupiter and his moons did very seriously disturb the comet1 however2 and when he came out from their midst1 though none the worse for his adventure1 he was forced to travel in an entirely new orbit1 and never managed to get back to his old pathway again4 ,but there are comets and comets1 some being heavier than others4 ,the comet named after ,donati1 albeit too transparent to hide a star1 was yet so immense in size that his weight was calculated by one astronomer to amount to as much as a mass of water forty thousand miles square and one hundred and nine yards deep4 ,when first noticed1 ,donati's comet had1 like all large comets1 a bright envelope of light round the nucleus4 ,after a while the one envelope grew into three envelopes1 and a new tail formed beside the principal tail1 which for a time was seen to bend gracefully into a curve1 like a splendid plume4 ,a third1 but much fainter tail1 also made its appearance1 and many angry-looking jets were poured out from the nucleus4 ,these changes took place while the comet was passing through the great heat of near neighborhood to the sun4 ,afterwards1 as he passed away1 he seemed gradually to cool down and grow quiet4 ,the singular changes in the appearance of ,newton's comet have been earlier noticed4 ,no marvel that he did undergo some alterations4 ,the tremendous glare and burning heat which that comet had to endure in his rush past the sun1 were more than twenty-five thousand times as much as the glare and heat of the fiercest tropical noonday ever known upon earth4 ,can we wonder that he should have shown 8signs of great excitement10 that his head should have grown larger and his tail longer8 ,it certainly was amazing1 and past comprehension1 that the said tail1 over ninety millions of miles in length1 should in four days have seemingly swept round in a tremendous half-circle1 so as first to point in one direction1 and then to point in just the opposite direction4 ,we are much in the habit of speaking about comets as traveling through the heavens with their tails streaming behind them4 ,but though this is sometimes the case1 it is by no means always4 ,the tails of comets always stream away from the sun--whether before or behind the comet's head seeming to be a matter of indifference4 ,as the comet comes hurrying along his orbit1 with ever-increasing speed1 towards the sun1 the head journeys first1 and the long tail follows after4 ,but as the comet rounds the loop of his orbit near the sun--the point nearest of all being called his perihelion--the head always remains towards the sun1 while the tail swings1 or seems to swing1 in a magnificent sweep round1 pointing always in the direction just away from the sun4 ,then1 as the comet journeys with slackening speed1 on the other side of his orbit1 towards the distant aphelion1 or farthest point from the sun1 he still keeps his head towards the sun4 ,so1 at this part of his passage1 in place of the head going first and the tail following after1 the tail goes first and the head follows after4 ,the comet thus appears to be moving backwards2 or1 like an engine pushing instead of drawing a train1 the head seems to be driving the tail before it4 ,illustration3 ,,great ,,comet ,,of #agdd4 ,illustration3 ,,the ,,first ,,comet ,,of #ahhh--;,,june #d4 ,the sun1 then1 acts on these bodies when they approach him1 produces in them important physical and chemical transformations1 and exercises on their developed atmosphere a repulsive force1 the nature of which is still unknown to us1 but the effects of which coincide with the formation and development of the tails4 ,the tails are thus1 in the extension of the cometary atmosphere1 driven back1 either by the solar heat1 by the light1 by electricity1 or by other forces2 and this extension is rather a motion in the ether than a real transport of matter1 at least in the great comets which approach very near the sun1 and in their immense luminous appendages4 ,the effects produced and observed are not the same in all comets1 which proves that they differ from each other in several respects4 ,the tails have sometimes been seen to diminish before the perihelion passage1 as in #ahce4 ,luminous envelopes have also been seen succeeding each other round the head1 concentrating themselves on the side opposite to the sun1 and leaving the central line of the tail darker than the two sides4 ,this is what happened in the ,donati comet and in that of #ahfa4 ,sometimes a secondary tail has been seen projected towards the sun1 as in #ahbd1 #ahej1 #ahea1 and #ahhj4 ,comets have been seen with the head enveloped in phosphorescence1 surrounding them with a sort of luminous atmosphere4 ,comets have also been seen with three1 four1 five1 and six tails1 like that of #agdd1 for example1 which appeared like a splendid aurora borealis rising majestically in the sky1 until1 the celestial fan being raised to its full height1 it was perceived that the six jets of light all proceeded from the same point1 which was nothing else but the nucleus of a comet4 ,on the other hand1 the nuclei themselves show great variations--some appear simply nebulous1 and permit the faintest stars to be visible through them2 others seem to be formed of one or more solid masses surrounded by an enormous atmosphere2 in others1 again1 a nucleus does not exist1 as in the ,southern comet of #ahhg4 ,one of the comets of #ahhh showed a triple nucleus and a bristling coma1 as may be seen in the cut4 ,we may1 then1 consider that the wandering bodies collected under the name of comets are of several origins and several different species4 ,why the tails of comets should so persistently avoid the sun it is impossible to say4 ,we do not even know whether the cause lies actually in the sun or in the comet4 ,astronomers speak of the 8repulsive energy0 with which the sun 8sweeps away0 from his neighborhood the light vapory matter of which the tails are made4 ,but the how and the wherefore of this strange seeming repulsion they can not explain4 ,for at the selfsame time the sun appears to be attracting the comet towards himself1 and driving the comet's tail away from himself4 ,a few of the more well-known comets have been mentioned2 but a year rarely passes in which at least one comet is not discovered1 though often only a small specimen1 sometimes even tailless and hairless4 ,no doubt many others pass unseen4 ,the large and grand ones only come to view now and then4 ,what are comets and meteorites made of8 ,respecting comets1 a good many ideas are put forth1 and a good many guesses are made1 as to 8burning gas10 8luminous vapor10 8beams of light10 and so on4 ,but in truth1 little is known about the matter4 ,respecting meteorites1 we can speak more certainly4 ,a good many meteorites have fallen to earth as aerolites1 and have been carefully examined4 ,they are found to contain nickel1 cobalt1 iron1 phosphorus1 and sometimes at least1 a large supply of hydrogen gas4 ,not only do solid aerolites fall half-burnt to the ground1 but even when the meteorites are quite consumed in the air1 the fine dust remaining still sinks earthward4 ,this fine dust has been found upon mountain-tops1 and has been proved by close examination to be precisely the same as the material of the solid aerolites4 ,a luminous body of sensible dimensions rapidly traverses space1 diffusing on all sides a vivid light--like a globe of fire of which the apparent size is often comparable with that of the moon4 ,this body usually leaves behind it a perceptible luminous train4 ,on or immediately after its appearance it often produces an explosion1 and sometimes even several successive explosions1 which are heard at great distances4 ,these explosions are also often accompanied by the division of the globe of fire into luminous fragments1 more or less numerous1 which seem to be projected in different directions4 ,this phenomenon constitutes what is called a meteor1 properly speaking1 or a bolide4 ,it is produced during the day as well as the night4 ,the light which it causes in the former case is greatly enfeebled by the presence of the solar light1 and it is only when it is developed with sufficient intensity that it can be perceived4 ,in the ,british ,museum there is a superb collection of meteorites4 ,they have been brought together from all parts of the earth1 and vary in size from bodies not much larger than a pin's-head up to vast masses weighing many hundred pounds4 ,there are also many models of celebrated meteorites1 of which the originals are dispersed through various other museums4 ,many of these objects have nothing very remarkable in their external appearance4 ,if they were met with on the sea-beach1 they would be passed by without more notice than would be given to any other stone4 ,yet what a history such a stone might tell us if we could only manage to obtain it6 ,it fell2 it was seen to fall from the sky2 but what was its course anterior to that movement8 ,where was it one hundred years ago1 one thousand years ago8 ,through what regions of space has it wandered8 ,why did it never fall before8 ,why has it actually now fallen8 ,such are some of the questions which crowd upon us as we ponder over these most interesting bodies4 ,some of these objects are composed of very characteristic materials4 ,take1 for example1 one of the more recent meteorites1 known as the ,rowton siderite4 ,this body differs very much from the more ordinary kind of stony meteorite4 ,it is an object which even a casual passer-by would hardly pass without notice4 ,its great weight would also attract attention1 while if it be scratched or rubbed with a file1 it would be found that it was not in any sense a stone1 but that it was a mass of nearly pure iron4 ,we know the circumstances under which that piece of iron fell to the earth4 ,it was on the #bjth of ,april1 #ahgf1 about #c4dj ,p4 ,m41 that a strange rumbling noise1 followed by a startling explosion1 was heard over an area of several miles in extent among the villages in ,shropshire4 ,about an hour after this occurrence1 a farmer noticed the ground in one of his grass-fields to have been disturbed1 and he probed the hole which the meteorite had made1 and found it1 still warm1 about eighteen inches below the surface4 ,some men working at no great distance had actually heard the noise of its descent1 but without being able to indicate the exact locality4 ,this remarkable object weighs #g pounds4 ,it is an irregular angular mass of iron1 though all its edges seem to have been rounded by fusion in its transit through the air1 and it is covered with a thick black film of the magnetic oxide of iron1 except at the point where it first struck the ground4 ,this siderite is specially interesting on account of its distinctly metallic character4 ,falls of the siderites1 as they are called1 are not so common as those of the stony meteorites2 in fact1 there are only a few known instances of meteoric irons having been actually seen to fall1 while the falls of stony meteorites are to be counted in scores or in hundreds4 ,the inference is that the iron meteorites are much less frequent than the stony ones4 ,it is a wonderful thought that we should really have these visitants from the sky1 solid metal or showers of dust1 coming to us from distant space4 ,if the dust of thousands of meteorites is always thus falling earthward1 one would imagine that it must in time add something to the weight of the earth4 ,and this actually is the case4 ,during the last three thousand years1 no less than one million tons of meteorite-dust must1 according to calculation1 have fallen to earth out of the sky4 ,a million tons is of course a mere nothing compared with the size of the world4 ,still1 the fact is curious and interesting4 ,it has been suggested that1 perhaps the flames of the sun are partly fed by vast showers of falling meteorites4 ,it has even been suggested that perhaps1 in long past ages1 the earth and the planets grew to their present size under a tremendous downpour of meteorites2 the numbers which now drop to earth being merely the thin remains of what once existed4 ,but for this guess there is no real foundation4 ,whether suns and worlds full-grown1 created as in an instant2 whether tiny meteorites in countless myriads to be used as stones in 8building20 whether vast masses of flaming gas1 to be gradually cooled and 8framed0 into shape--which ever may have come first1 and whichever may have been the order of ,god's working--still that 8first0 was made by him2 still he throughout was the ,master-builder4 ,illustration3 ,,great ,,comet ,,of #afhj4 ,a few words more about 8comet-visitors40 ,many comets1 as already stated1 belong to our ,solar ,system1 though whether they have always so belonged is another question4 ,it is not impossible that they may once upon a time have wandered hence from a vast distance1 and1 being caught prisoner by the powerful attraction of ,jupiter or one of his three great brother-planets1 have been compelled thenceforth to travel in a closed pathway round the sun4 ,illustration3 ,,great ,,comet ,,of #agfi4 ,there are also many comets which come once only to our system1 flashing round past the sun1 and rushing away in quite another direction1 never to return4 ,where do these comets come from8 ,and where do they go8 ,from other suns--brother suns to ours8 ,it may be4 ,one is almost disposed to think that it must be so4 ,do we ever think what an immense voyage they must have made to come from there to here8 ,do we imagine for how many years they must have flown through the dark immensity to plunge themselves into the fires of our sun8 ,if we take into account the directions from which certain comets come to us1 and if we assign to the stars situated in that region the least distances consistent with known facts1 we find that these comets certainly left their last star more than twenty millions of years ago4 ,in thus putting to us from the height of their celestial apparitions so many notes of interrogation on the grandest problems of creation1 comets assume to our eyes an interest incomparably greater than that with which superstition blindly surrounded them in past ages4 ,when we reflect for a moment that a certain comet which shines before us in the sky came originally from the depths of the heavens1 that it has traveled during millions of years to arrive here1 and that consequently it is by millions of years that we must reckon its age if we wish to form any idea of it1 we can not refrain from respecting this strange visitor as a witness of vanished eras1 as an echo of the past1 as the most ancient testimony which we have of the existence of matter4 ,but what do we say8 ,these bodies are neither old nor young4 ,there is nothing old1 nothing new--all is present4 ,the ages of the past contemplate the ages of the future1 which all work1 all gravitate1 all circulate1 in the eternal plan4 ,musing1 you look at the river which flows so gently at your feet1 and you believe you see again the river of your childhood2 but the water of to-day is not that of yesterday1 it is not the same substance which you have before your eyes1 and never1 never shall this union of molecules1 which you behold at this moment1 come back there--never till the consummation of the ages6 ,if the appearance of comets forebodes absolutely nothing as to the microscopical events of our ephemeral human history1 it is not the same with the effects which might be produced by their encounter with our wandering planet4 ,in such an encounter there is nothing impossible4 ,no law of celestial mechanics forbids that two bodies should come into collision in their course1 be broken up1 pulverized1 and mutually reduced to vapor4 ,i have before described some of the tremendous outbursts seen on the surface of our sun4 ,it is believed that in these outbursts matter is expelled1 or driven forth1 with such fearful violence as to send it whirling through space1 never to fall back to the sun4 ,some meteorites may have their births thus4 ,so also may some comets4 ,and if all the stars are suns--huge fiery globes like our sun1 and subject like him to tremendous eruptions--they too1 probably1 send out comets and meteorites to wander through space4 ,whether or no comets come into existence in any such manner1 one thing seems pretty certain4 ,those comets which come to us from outside our system must come from some other system4 ,and the nearest systems known are those of the stars4 ,the nearest star of all1 whose distance has been measured1 is ,alpha ,centauri4 ,it has been roughly calculated that a comet1 passing direct from ,alpha ,centauri to our sun1 would take about twenty millions of years for his journey4 ,but here we tread upon very doubtful ground4 ,many matters1 at present unknown to us1 might greatly affect the result of such a calculation4 ,also it is by no means impossible that other stars lie really much nearer to us than ,alpha ,centauri1 whose distance astronomers have not yet attempted to measure4 ,illustration3 ,,baron ,,alexander ,,von ,,humboldt4 8,in order to complete our view10 says ,alexander ,von ,humboldt1 8of all that we have learned to consider as appertaining to our ,solar ,system1 which now1 since the discovery of the small planets1 of the interior comets of short revolutions1 and of the meteoric asteroids1 is so rich and complicated in its form1 it remains for us to speak of the ring of zodiacal light4 ,those who have lived for many years in the zone of palms must retain a pleasing impression of the mild radiance with which the zodiacal light1 shooting pyramidally upward1 illumines a part of the uniform length of tropical nights4 ,i have seen it shine with an intensity of light equal to the ,milky ,way in ,saggitarius1 and that not only in the rare and dry atmosphere of the summit of the ,andes1 at an elevation of from thirteen to fifteen thousand feet1 but even on the boundless grassy plains of ,venezuela1 and on the seashore1 beneath the ever-clear sky of ,cumana4 ,this phenomenon was often rendered especially beautiful by the passage of light1 fleecy clouds1 which stood out in picturesque and bold relief from the luminous background4 8,this phenomenon1 whose primordial antiquity can scarcely be doubted1 is not the luminous solar atmosphere itself1 which can not be diffused beyond nine-tenths of the distance of ,mercury4 ,with much probability we may regard the existence of a very compressed ring of nebulous matter1 revolving freely in space around the sun between the orbits of ,venus and ,mars1 as the material cause of the zodiacal light4 ,these nebulous particles may either be self-luminous or receive their light from the sun4 8,i have occasionally been astonished1 in the tropical climates of ,south ,america1 to observe the variable intensity of the zodiacal light4 ,as ,i passed the nights1 during many months1 in the open air1 on the shores of rivers and on plains1 ,i enjoyed ample opportunities of carefully examining this phenomenon4 ,when the zodiacal light had been most intense1 ,i have observed that it would be weakened for a few minutes1 until it again suddenly shone forth in full brilliancy4 ,in a few instances ,i have thought ,i could perceive1 not exactly a reddish coloration1 nor the lower portion darkened in an arc-like form1 nor even a scintillation1 but a kind of flickering and wavering of the light4 ,must we suppose that changes are actually in progress in the nebulous ring8 ,or is it not more probable that processes of condensation may be going on in the uppermost strata of the air1 by means of which the transparency--or1 rather1 the reflection of light--may be modified in some peculiar and unknown manner8 ,an assumption of the existence of such meteorological causes on the confines of our atmosphere is strengthened by the sudden flash and pulsations of light which have been observed to vibrate for several seconds through the tail of a comet4 ,during the continuation of these pulsations it has been noticed that the comet's tail was lengthened by several degrees1 and then again contracted40 ,,chapter ,,xxii4 ,,many ,,suns4 ,once more we have to wing our flight far1 far away from the busy ,solar ,system where we live2 away from whirling planets1 moons1 meteorites1 all shining with reflected sunlight2 away from the great central sun himself1 our own particular bright star4 ,once more we have1 in imagination1 to cross the vast1 black1 empty space--is it black1 and is it empty1 had we sight to see things as they are8--separating our sun from other suns1 our star from other stars4 ,for the sun is a star--only a star4 ,and stars are suns--big1 blazing suns4 ,one is near1 and the others are far away4 ,that is the difference4 ,we have no longer to do with bodies merely reflecting another's light--always dark on one side and bright on the other--but with burning bodies1 shining all round by their own light4 ,we have no longer to picture just one single star with his surrounding worlds1 but we have to fix our thoughts upon the great universe of stars or suns in countless millions4 ,the earth is forgotten1 with its small and ephemeral history4 ,the sun himself1 with all his immense system1 has sunk in the infinite night4 ,on the wings of inter-sidereal comets we have taken our flight towards the stars1 the suns of space4 ,have we exactly measured1 have we worthily realized the road passed over by our thoughts8 ,the nearest star to us reigns at a distance of #bge1jjj times our distance from the sun2 out to that star an immense desert surrounds us1 the most profound1 the darkest1 and the most silent of solitudes4 ,the solar system seems to us very vast2 the abyss which separates our world from ,mars1 ,jupiter1 ,saturn1 and ,neptune1 appears to us immense2 relatively to the fixed stars1 however1 our whole system represents but an isolated family immediately surrounding us3 a sphere as vast as the whole solar system would be reduced to the size of a simple point if it were transported to the distance of the nearest star4 ,the space which extends between the solar system and the stars1 and which separates the stars from each other1 appears to be entirely void of visible matter1 with the exception of nebulous fragments1 cometary or meteoric1 which circulate here and there in the immense voids4 ,nine thousand two hundred and fifty systems like ours1 bounded by ,neptune1 would be contained in the space which isolates us from the nearest star6 ,it is marvelous that we can perceive the stars at such a distance4 ,what an admirable transparency in these immense spaces to permit the light to pass1 without being wasted1 to thousands of billions of miles6 ,around us1 in the thick air which envelops us1 the mountains are already darkened and difficult to see at seventy miles2 the least fog hides from us objects on the horizon4 ,what must be the tenuity1 the rarefaction1 the extreme transparency of the ethereal medium which fills the celestial spaces6 ,the sun is center and ruler and king in his own system4 ,but as a star1 he is only one among many stars1 some greater1 some less than himself4 ,from the far siderial heavens he is hardly recognized even as a star among the constellations1 so faint is his light4 ,do the suns which surround us form a system with that which illuminates us1 as the planets form one round our solar focus1 and does our sun revolve round an attractive center8 ,does this center1 the point of the revolutions of many suns1 itself revolve round a preponderating center8 ,in a word1 is the visible universe organized in one or several systems8 ,no ,divine revelation comes to instruct men on the mysteries which interest them most--their personal or collective destinies4 ,we have now1 as ever1 but science and observation to answer us4 ,a problem so vast as this is still far from receiving even an approximate solution4 ,from whatever point of view we consider it1 we find ourselves face to face with the infinite in space and time4 ,the present aspect of the universe immediately brings into question its past and its future state1 and then the whole of united human learning supplies us in this great research with but a pale light1 scarcely illuminating the first steps of the dark and unknown road on which we are traveling4 ,however1 such a problem is worthy of engaging our attention1 and positive science has already made sufficient discoveries in the knowledge of the laws of nature to permit us to attempt to penetrate these great mysteries4 ,what is it that the general observation of the heavens--what is it that sidereal synthesis teaches us on our real situation in infinitude8 ,illustration3 ,a ,,telescopic ,,field ,,in ,,the ,,milky ,,way4 ,in the calm and silent hours of beautiful evenings1 what pensive gaze is not lost in the vague windings of the ,milky ,way1 in the soft and celestial gleam of that cloudy arch1 which seems supported on two opposite points of the horizon1 and elevated more or less in the sky according to the place of the observer and the hour of the night8 ,while one-half appears above the horizon1 the other sinks below it1 and if we removed the earth1 or if it were rendered transparent1 we should see the complete ,milky ,way1 under the form of a great circle1 making the whole circuit of the sky4 ,the scientific study of this trail of light1 and its comparison with the starry population of the heavens1 begins for us the solution of the great problem4 ,let us point a telescope towards any point of this stupendous arch4 ,suddenly hundreds1 thousands of stars show themselves in the telescopic field1 like needle-points on the celestial vault4 ,let us wait for some moments1 that our eye may become accustomed to the darkness of the background1 and the little sparks shine out by thousands4 ,let us leave the instrument pointed motionless towards the same region1 and there slowly passes before our dazzled vision the distant army of stars4 ,in a quarter of an hour we see them appear by thousands and thousands4 ,william ,herschel counted three hundred and thirty-one thousand in a width of #e in the constellation ,cygnus1 so nebulous to the naked eye4 ,if we could see the whole of the ,milky ,way pass before us1 we should see eighteen millions of stars4 ,this seed-plot of stars is formed of objects individually invisible to the naked eye1 below the sixth magnitude2 but so crowded that they appear to touch each other1 and form a nebulous gleam which all human eyes1 directed to the sky for thousands of years1 have contemplated and admired4 ,since it is developed like a girdle round the whole circuit of the sky1 we ourselves must be in the ,milky ,way4 ,the first fact which impresses our mind is1 that our sun is a star of the ,milky ,way4 ,thought travels fast--faster than a comet1 faster than light4 ,a rushing comet would1 it is believed1 take twenty millions of years to cross the chasm between the nearest known fixed star and us4 ,light1 flashing along at the rate of about one hundred and eighty-six thousand miles a second1 will perform the same journey in four years and a third4 ,but thought can overleap the boundary in less than a single moment4 ,each star that we see in the heavens is to our eyesight simply one point of light4 ,the brighter stars are said to be of greater magnitude1 and the fainter stars of lesser magnitude2 yet1 one and all1 they have no apparent size4 ,the most powerful telescope1 though it can increase their brilliancy1 can not add to their size4 ,a planet1 which to the naked eye may look like a star1 will1 under a telescope1 show a disk1 the breadth of which can be measured or divided2 but no star has any real1 visible disk in the most powerful telescope yet constructed4 ,the reason of this is the enormous distance of the stars4 ,far off as many of the planets lie1 yet the farthest of them is as a member of our household compared with the nearest star4 ,i have already tried to make clear the fact of their vast distance4 ,light1 which comes to us from the sun in eight minutes and a half1 takes over four and a third years to reach us from ,alpha ,centauri4 ,from this four-years-and-a-third length of journey between ,alpha ,centauri and earth1 the numbers rise rapidly to twenty years1 fifty years1 seventy years1 even hundreds of years4 ,the distance of most of the stars is completely beyond our power to measure4 ,the whole orbit of our earth1 nay1 the whole wide orbit of the far-off ,neptune1 would dwindle down to one single point1 if seen from the greater number of the stars4 ,it used to be believed that1 taking the stars generally1 there was probably no very marked difference in their size1 their kind1 their brightness4 ,some of course would be rather larger1 and others rather smaller2 still it was supposed that they might be roughly classed as formed much on the same scale and the same plan4 ,but doubts are now felt about this notion4 ,for a very similar idea used to be held with regard to the ,solar ,system4 ,the wonderful variety of form and richness in numbers1 now known to abound within its limits1 are discoveries of late years4 ,may not the same variety in kind and size be found also among the stars8 ,the more we look into the heavens1 the more we find that dull1 blank uniformity is not to be seen there4 ,it is the same upon earth4 ,man builds his little rows of boxlike houses side by side1 each one exactly like all the rest1 or dresses his thousand soldiers in coats of the same cut and color1 or repeats a neat leaf-design hundreds of times on carpets or wall-papers2 but ,god never makes two leafs or two blades of grass alike4 ,wholesale turning out of things after one pattern is quite a human idea1 not divine4 ,we know so much about the stars as that some are at least considerably larger and some considerably smaller than others4 ,when one star is seen to shine brightly1 and another beside it shines dimly1 we are apt to think that the brightest must be the nearest4 ,yet it is often impossible for us to say how much of the difference is owing to the greater distance of one or the other1 to the greater size of one or the other1 or to the greater brilliancy of one or the other4 ,in many instances we do know enough to be quite sure that there is a great difference1 not only in the distance of the stars1 but in their size1 their kind1 their brightness4 ,the stars have been lately classed by one or two astronomers into four distinct orders or degrees--partly depending on their color4 ,the first class is that of the ,white ,suns4 ,these are said to be the grandest and mightiest of all4 ,the star ,sirius belongs to the order of ,white ,suns4 ,secondly comes the class of ,golden ,suns4 ,to these blazing furnaces of yellow light1 second only to the white-light stars1 belongs our own sun4 ,thirdly1 there are numbers of stars called ,variable ,stars1 the light of which is constantly changing1 now becoming more1 now becoming less4 ,fourthly1 there is the class of small ,red ,suns1 about which not much is known4 ,these four orders or divisions do not by any means include all the stars1 or even all the single stars4 ,roughly speaking1 however1 the greater number of single stars1 and many also of the double stars1 belong to one or another of the above classes4 ,when we talk of the different sizes of the different stars1 it should be plainly understood that we have no means of directly measuring them4 ,a point of light showing no disk1 no surface1 no breadth1 can not be measured1 for there is nothing to measure4 ,in certain cases we are not entirely without the power of judging4 ,the distances of a few of the stars from us have been found out4 ,knowing how far off any particular star is1 astronomers are able to calculate exactly how bright our own sun would look at that same distance4 ,if they find that our sun would shine just as the star in question shines1 there is some reason for supposing that our sun and the star may be of the same size4 ,if our sun would shine more brightly than the star shines1 there is some reason for supposing that the star may be smaller than our sun4 ,if our sun would shine more dimly than the star shines1 there is some reason for supposing that the star may be larger than our sun4 ,other matters1 however1 have to be considered4 ,suppose we find a star at a certain distance shining twice as brilliantly as our own sun would shine at that same distance4 ,naturally1 then1 we say1 ,that star must be much larger than our sun4 ,the reasoning may be mistaken4 ,we do not know the fact4 ,what if1 instead of being a much larger sun1 it is only a much brighter sun8 ,this possibly must be allowed for4 ,it has1 indeed1 been strongly doubted by one astronomer1 after close study of the sun1 whether any surface of any star could exceed the surface of our sun in its power of light and heat4 ,but ,sirius sheds actually forty-eight times as much light around it as does our sun2 we are not exactly entitled to say that ,sirius is forty-eight times as big as the sun1 but we can say that ,sirius is forty-eight times as brilliant or as splendid4 ,in making this calculation we have taken a lower determination of the brightness of ,sirius relatively to the sun than some other careful observations would have warranted4 ,it will thus be seen that if there be any uncertainty in our result it must only be as to whether ,sirius is not really more than forty-eight times as bright as the sun4 ,when we picture to ourselves the star-depths1 the boundless reaches of heavenly space1 with these countless blazing suns scattered broadcast throughout1 we have not to picture an universe in repose4 ,on the contrary1 all is life1 stir1 energy4 ,just as in the busy whirl of our ,solar ,system no such thing as rest is to be found1 so also it seems to be in the wide universe4 ,every star is in motion4 8,fixed10 as we call them1 they are not fixed4 ,invisible as their movements are to our eyes through immensity of distance1 yet all are moving4 ,those silent1 placid1 twinkling specks of light are1 in reality1 huge1 roaring1 seething1 tumultuous furnaces of fire and flame1 heat and radiance4 ,each1 too1 is hurrying along his appointed pathway in space4 ,some move faster1 some move more slowly4 ,one mile per second2 ten miles per second2 twenty1 thirty1 forty1 fifty miles per second1--thus varying are their rates of speed4 ,but whether fast or whether slowly1 still onward and ever onward they press4 ,some are rushing towards us1 some are rushing away from us4 ,some are speeding to the right1 some are speeding to the left4 ,the fine star ,arcturus1 which any one may admire every evening on the prolongation of the tail of the ,great ,bear1 is slowly withdrawing from the fixed point where the celestial charts placed it two thousand years ago1 and is moving towards the southwest4 ,it takes eight hundred years to describe a space in the sky equal to the apparent diameter of the moon2 nevertheless1 this displacement was sufficiently perceptible to attract attention more than a century and a half ago1 for ,halley had noticed it in #agah1 as well as those of ,sirius and ,aldebaran4 ,however slow it may appear at the distance we are from ,arcturus1 this motion is1 at a minimum1 #a1fcg millions of miles a year4 ,sirius takes #a1cch years to pass over the same angular space in the sky2 at the distance of that star this is1 at a minimum1 #cig millions of miles per annum4 ,the study of the proper motions of the stars has made the greatest progress in the last half-century1 and especially in recent years4 ,all the stars visible to the naked eye and a large number of telescopic stars show displacements of this kind4 ,where are they going8 ,does any single star ever return to his starting-point--wherever that starting-point may have been8 ,do they journey in vast circles or ellipses1 round some far-distant center8 ,what controls them all8 ,is it the mighty power of some such center1 or does each star1 by his faint and distant attraction1 help to control all his brother-stars1 to guide them on their appointed path1 to preserve the delicate balance of a universe8 ,how little we know about the matter6 ,only so much we can tell--that the controlling and restraining hand of ,god is over the whole4 ,whether by the attraction of one great center or by the united influences of a thousand fainter attractions1 he steers each radiant sun upon its heavenly path1 8upholding all things by the words of his power40 ,there is no blundering1 no confusion1 no entanglement4 ,all is perfect order1 calm arrangement1 restrained energy4 ,,chapter ,,xxiii4 ,,some ,,particular ,,suns4 ,in the constellation of the ,swan there is a little1 dim1 sixth-magnitude star1 scarcely to be seen without a telescope4 ,this star1 #fa ,cygni by name1 is the first whose distance from us it was found possible to determine4 ,we may think it strange that so faint a star was even attempted4 ,would not astronomers have naturally supposed it to be one of the farther-distant stars8 ,no1 they did not4 ,for though #fa ,cygni showed but a dim light1 yet his motion--not the daily apparent motion1 but the real motion as seen from earth--was found to be so much more rapid than the motion of most other stars that they rightly guessed #fa ,cygni to be a rather near neighbor of ours4 ,do not misunderstand me1 when ,i speak of a 8more rapid motion10 and of 8rather near neighborhood40 ,the real rate of #fa ,cygni's rush through space is believed to be about forty miles each second1 or one thousand four hundred and fifty millions of miles each year4 ,all we can perceive of this quick motion is that1 in the course of three hundred and fifty years1 #fa ,cygni travels over a space in the sky about as long as the breadth of the full moon4 ,little enough1 yet very far beyond what can be detected in the greater number of even the brightest stars4 ,then1 again1 as to the near neighborhood of this star1 #fa ,cygni is near enough to have his distance measured1 and that is saying a good deal4 ,alpha ,centauri1 the nearest star of which we know in the southern heavens1 is two hundred and seventy-five thousand times as far distant as the sun4 ,but #fa ,cygni1 the nearest star of which we know in the northern heavens1 is nearly twice as far away as ,alpha ,centauri4 ,illustration3 ,,cygnus4 ,we call #fa ,cygni a star1 for so he appears to common observers4 ,in reality1 instead of being only one star1 the speck of light which we call #fa ,cygni consists of two stars4 ,the two are separated by a gap about half as wide again as the wide gap between the sun and ,neptune4 ,yet so great is their distance from us that to the naked eye the two seem to be one4 ,these two suns would together make a sun only about one-third as large as our sun4 ,they differ in size1 the quicker movements of one showing it to be the smaller2 and it is by means of their known distance from one another1 and their known rate of motion1 that their size1 or rather their weight1 can be roughly calculated4 ,of course neither of the two shows any actual measurable disk4 ,so much and so little is with tolerable certainty known about this particular pair of suns4 ,next let us turn to ,alpha ,centauri--named ,alpha1 the first letter of the ,greek alphabet1 because it is the brightest star in the constellation of the ,centaur4 ,the second brightest star in a constellation is generally called ,beta1 the third ,gamma1 the fourth ,delta1 and so on2 just as if we were to name them ,a1 ,b1 ,c1 ,d1 in order of brightness4 ,the constellation ,centaur lies in the southern heavens1 close to the beautiful constellation called the ,southern ,cross1 and is invisible in the northern hemisphere4 ,of all the stars shining in the heavens round our earth1 two only--,sirius and ,canopus--show greater brilliancy than ,alpha ,centauri4 ,as in the case of #fa ,cygni1 astronomers were led to attempt the measurement of ,alpha ,centauri's distance1 by noticing how much more distinct were his movements than the movements of other stars1 though less rapid both to the eye and in reality than those of #fa ,cygni4 ,alpha ,centauri's rate of motion is some thirteen miles each second4 ,and this1 so far as we yet know1 is our sun's nearest neighbor in the heavens outside his own family circle4 ,strange to say1 ,alpha ,centauri1 like #fa ,cygni1 consists1 not of a single star1 but of a pair of stars4 ,it is a two-sun system--whether or no surrounded by planets can not be told4 ,we can only reason from what we see to what we do not see4 ,and as ,god did not form our earth 8in vain10 and did not form our sun 8in vain10 so we firmly believe that he did not form 8in vain0 any one of his myriads of suns scattered through space4 ,what is1 has been1 or will be the particular use of each one1 it would be rash to attempt to say4 ,but that many among them have1 like our own sun1 systems of worlds revolving round them1 we may safely consider very probable4 ,illustration3 ,,stars ,,whose ,,distances ,,are ,,best ,,known4 7,see ,table47 ,the two suns of the ,alpha ,centauri double-star are separated by a distance about twenty-two times as great as the distance of the earth from the sun1 yet to the naked eye they show as a single star4 ,here again one is much smaller than the other2 and the smaller revolves round the larger in about eighty-five years4 ,it is believed that the two together would form a sun about twice as large and heavy as our sun4 ,this belief is strengthened by the great brilliancy of ,alpha ,centauri4 ,our own sun1 placed at that distance from us1 would shine only one-third as brightly as he does4 ,,stars ,,whose ,,distances ,,are ,,best ,,known4 ---------------------------------------- ---------- ,,name ,,of ,,star4 ,,magnitude4,,distance ,,in ,,miles4 ---------------------------------------- ---------- #a ,alpha ,centauri1 #a4j #be trillions4 #b #fa ,cygni1 #e4a #dc 0 #c #b1cih1 ,draco1 #h4b #ee 0 #d ,sirius1 #a4j #eh 0 #e #i1ceb1 ,lacaille1 #g4e #ff 0 #f ,procyon1 #a4c #ga 0 #g ,lalande1 #ba1beh1 #h4e #gd 0 #h ltzen1 #aa1fgg1 #i4j #gd 0 #i ,sigma ,draconis1 #d4g #gh 0 #aj ,aldebaran1 #a4e #ha 0 #aa ,epsilon ,indi1 #e4b #hg 0 #ab ltzen1 #ag1dae1 #i4j #id 0 #ac #a1eaf1 ,draco1 #g4j #aja 0 #ad ,omicron ,eridani1 #d4d #aja 0 #ae ,altair1 #a4f #aja 0 #af ,bradley1 #c1jgg1 #e4e #aja 0 #ag ,eta ,cassiopei1 #c4f #aah 0 #ah ,vega1 #a4j #abh 0 #ai ,capella1 #a4b #agd 0 #bj ,arcturus1 #a4j #bjd 0 #ba ,pole ,star1 #b4a #bae 0 #bb ,mu ,cassiopei1 #e4b #cbj 0 #bc #a1hcj1 ,groombridge1 #f4e #dbf 0 ---------------------------------------- ---------- ,this table presents the most trustworthy data which we have yet obtained with reference to stellar distances4 ,as a great number of attempts have been made on stars which1 by their brightness or by the magnitude of their proper motion1 would appear to be the nearest to us1 we may believe that the star now considered as the nearest is really so1 and that there is no other less distant4 ,thus our sun1 a star in the immensity1 is isolated in infinitude1 and the nearest sun reigns at twenty-five trillions of miles from our terrestrial abode4 ,notwithstanding its unimaginable velocity of #ahf1djj miles a second1 light moves1 flies1 during four years and one hundred and twenty-eight days to come from this sun to us4 ,sound would take more than three millions of years to cross the same abyss4 ,at the constant velocity of thirty-seven miles an hour1 an express train starting from the sun ,alpha ,centauri would not arrive here till after an uninterrupted course of nearly seventy-five millions of years4 ,here1 then1 are the nearest suns to us4 ,these stars1 twenty-three in number1 are almost the only ones which have shown a perceptible parallax2 still the result is very doubtful for the last four1 of which the parallax is less than a tenth of a second4 ,attempts have been made to ascertain the parallax of all the stars of the first magnitude1 and the result has been negative for those which are not entered in this list4 ,canopus1 ,rigel1 ,betelgeuse1 ,achernar1 ,alpha of the ,cross1 ,antares1 ,spica1 and ,fomalhaut1 do not show a perceptible parallax4 ,the fine star ,alpha ,cygni1 which shines near #fa ,cygni1 does not present to the most accurate researches any trace of fluctuation3 it is1 then1 incomparably more distant than its modest neighbor--at least five times1 and perhaps twenty times1 fifty times1 one hundred times beyond that4 ,what must be the colossal size and amazing light of these suns1 of which the distance is greater than three hundred to four hundred trillions of miles1 and which nevertheless still shine with so splendid a brightness6 ,we did not know the distance of any stars till the year #ahdj4 ,this shows how recent this discovery is2 indeed1 we have hardly now begun to form an approximate idea of the real distances which separate the stars from each other4 ,the parallax of #fa ,cygni1 the first which was known1 was determined by ,bessel1 and resulted from observations made at ,knigsberg from #ahcg to #ahdj4 ,since then1 the first figure obtained has been corrected by a series of more recent observations4 ,such distances are amazing and almost terrifying to the imagination4 ,the mind is bewildered and almost overwhelmed when attempting to form a conception of such portions of immensity1 and feels its own littleness1 the limited nature of its powers1 and its utter incapacity for grasping the amplitudes of creation4 ,but though it were possible for us to wing our flight to such a distant orb as #fa ,cygni1 we should still find ourselves standing only on the verge of the starry firmament where ten thousands of other orbs a thousand times more distant would meet our view4 ,we have reason to believe that a space equal to that which we are now considering intervenes between most of the stars which diversify our nocturnal sky4 ,the stars appear of different magnitudes2 but we have the strongest reason to conclude that in the majority of instances this is owing1 not to the difference of their real magnitudes1 but to the different distances at which they are placed from our globe4 ,if1 then1 the distance of a star of the first or second magnitude1 or those which are nearest to us1 be so immensely great1 what must be the distance of stars of the sixteenth or twentieth magnitude1 which can be distinguished only by the most powerful telescopes8 ,some of these must be many millions of times more distant than the nearest star whose distance now appears to be determined4 ,and what shall we think of the distance of those which lie beyond the reach of any telescope that has yet been constructed1 stretching beyond the utmost limits of mortal vision1 within the unexplored regions of immensity8 ,here even the most vigorous imagination drops its wing1 and owns itself utterly unable to penetrate this mysterious and boundless unknown4 ,turning now from the sun1 whose distance was first measured1 and from the nearest star with which we are acquainted1 let us think about the most radiant star in the heavens--,sirius1 8the blazing ,dog-star of the ancients20 named by one astronomer 8the king of suns40 ,first1 as to the color of ,sirius4 ,he belongs to the order of 8,white ,suns10 and among all the white suns known to us1 ,sirius ranks as chief4 ,there may be many at greater distances far surpassing him in size1 and weight1 and brilliancy2 but we can only speak so far as we know4 ,strange to say1 ,sirius was not always a 8white sun20 for ancient writers describe him as being1 in their days1 a red star4 ,this change is very singular1 and difficult to understand4 ,but ,sirius is not the only example of the kind4 ,many alterations in color have been noticed as taking place1 often in a much shorter space of time4 ,for instance1 one star1 which was a white sun in the days of ,herschel1 is now a golden sun4 ,secondly1 as to the distance of ,sirius4 ,like a few other stars1 ,sirius lies not quite so far away as to be beyond reach of measurement4 ,no base-line upon earth would cause the slightest seeming change of position in him2 but as our earth journeys round the sun1 the line from one side of her orbit to the other is found wide enough4 ,a base-line of one hundred and eighty-six millions of miles does cause just a tiny seeming change4 ,it is very little even with ,alpha ,centauri1 and with ,sirius it is much less4 ,the 8displacement0 of ,sirius is so slight that to measure his distance with exactness is impossible4 ,sirius lies more than twice as far away from earth as ,alpha ,centauri4 ,to reach ,sirius1 the straight line between earth and sun must be repeated six hundred and twenty-six thousand times4 ,light1 which reaches us from the sun in eight minutes and a half1 and from ,alpha ,centauri in four years and a third1 can not reach us from ,sirius in less than nine years4 ,thirdly1 as to the size of ,sirius4 ,here1 of course1 we are in difficulties4 ,radiantly as ,sirius shines on a clear night1 and dazzling as he looks through a powerful telescope1 he shows no real disk or round surface1 but only appears as one point of brilliant light4 ,some believe him to be much the same size as our sun1 while others believe him to be very much larger4 ,but we have no certain ground to rest upon4 ,the only safe method of calculating the probable size--or1 rather1 weight--of a star is through the discovery of a companion1 and a knowledge of its distance from the chief star1 and its time of revolution round the chief star4 ,fourthly1 as to the motions of ,sirius--not his nightly apparent movement1 caused by the earth's turning on her axis1 but his real journey through space4 ,for a long while it was only possible to observe the movements of a star when the star was traveling sideways to us across the sky4 ,a star coming straight towards us1 or going straight away from us1 would seem to be at rest4 ,lately1 however1 by means of that remarkable instrument1 the spectroscope1 it has been found possible to measure the motions of stars coming towards or going away from us4 ,this is possible as yet only in a few scattered cases1 but among those few is the brilliant ,sirius4 ,the sideways motion of ,sirius had been known before4 ,it now appears that he does not move exactly sideways to us1 but is rushing away in a slanting direction at the rate of thirty miles each second1 or about one thousand millions of miles a year4 ,how many millions upon millions of miles ,sirius must now be farther from us than in the days of the ancients6 ,yet he shines still1 the most brilliant star in the sky4 ,so small a matter are all those millions of miles1 compared with the whole of his vast distance from us1 that we do not perceive any lessening of light4 ,it is an interesting fact that while ,sirius is moving away from us1 we are also moving away from him4 ,our 8first station ahead10 in the constellation ,hercules1 lies exactly in the opposite direction from ,sirius4 ,but the sun does not move so fast as ,sirius4 ,he is believed to accomplish only about one hundred and fifty millions of miles each year1 drawing all his planets with him4 ,fifthly1 has ,sirius a family1 or system1 like that of our sun8 ,why not8 ,common sense and reason alike answer with a 8,probably1 yes0--not only about ,sirius1 but about other stars also4 ,no doubt the systems--the number1 size1 weight1 speed1 distance1 and kind of planets--differ very greatly4 ,no doubt there are boundless varieties of beauty and grandeur4 ,but that our sun should be the head of so wonderful and complex a system1 that his rays should be the source of life and heat to so many dependents1 and that all the myriads of suns besides should be mere solitary lamps shining into empty space1 warming1 lighting1 controlling nothing1 is an idea scarcely to be looked in the face4 ,of course1 there may be other and different uses for some of these suns1 beyond our understanding4 ,we must not be positive in the matter4 ,it seems1 however1 pretty certain that ,sirius at least is not a solitary1 unattended sun4 ,astronomers1 carefully watching his movements1 were somewhat perplexed4 ,as with ,uranus1 the attraction of a heavy body beyond was suspected from the nature of the planet's motions1 so it happened again with the far more distant ,sirius4 ,astronomers could only explain his movements by supposing the attraction of some large and near satellite4 ,no one knew anything about such a satellite1 but it was felt that one must exist4 ,nearly twenty years had elapsed after ,bessel had predicted the disturber of ,sirius before the telescopic discovery which confirmed it was made4 ,the circumstances under which that discovery was made are not1 indeed1 so dramatic as those which attended the discovery of ,neptune1 but yet they have an interest of their own4 ,in ,february1 #ahfb1 ,alvan ,clark ,sons1 the celebrated telescope-makers1 of ,cambridge1 ,massachusetts1 were completing a superb eighteen-inch object-glass for the ,chicago ,observatory4 ,turning the instrument on ,sirius1 for the purpose of trying it1 the practiced eye of ,alvan ,graham ,clark1 the son1 soon detected something unusual1 and he exclaimed1 8,why1 father1 the star has a companion60 ,the father looked1 and there was a faint companion due east from the bright star1 and distant about ten seconds of a degree4 ,this was exactly the predicted direction of the companion of ,sirius1 and yet the observers knew nothing of the prediction4 ,as the news of this discovery spread1 many great telescopes were pointed on ,sirius2 and it was found that when observers knew exactly where to look for the object1 many instruments would show it4 ,the new companion star to ,sirius lay in the true direction1 and it was now watched with the keenest interest1 to see whether it also was moving in the way it should move1--if it were really the body whose existence had been foretold4 ,four years of observation showed that this was the case1 so that hardly any doubt could remain that the telescopic discovery had been made of the star which had caused the inequality in the motion of ,sirius4 ,it is certainly a very remarkable fact that1 out of the thousands of stars with which the heavens are adorned1 no single star has yet been found which certainly shows an appreciable disk in the telescope4 ,we are aware that some skillful observers have thought that certain small stars do show disks2 but we may lay this aside1 and appeal only to the ordinary fact that our best telescopes turned on the brightest stars show merely glittering points of light1 so hopelessly small as to elude our most delicate micrometers4 ,the ideal astronomical telescope is1 indeed1 one which will show ,sirius1 or any other bright star1 as nearly identical as possible with ,euclid's definition of a point1 being that which has no parts and no magnitude4 ,lastly1 what is ,sirius made of8 ,the late discovery of spectrum analysis1 or of the instrument called the spectroscope1 helps us here4 ,a little further explanation on this subject will be given later4 ,it may be observed in passing that before the said discovery1 astronomers can scarcely be asserted to have known with any certainty that stars were suns4 ,they could1 indeed1 be sure that at the vast distances of the fixed stars no bodies1 shining by merely reflected light1 could possibly be visible to us4 ,but there knowledge stopped4 ,now we can say more4 ,now the spectroscope1 by breaking up and dividing for us the slender ray of light traveling from each star1 has shown to us something of the nature of the stars4 ,now we know that the stars1 like our sun1 are burning bodies1 surrounded by atmospheres full of burning gas4 ,it has even been found out that in ,sirius there are large quantities of sodium and magnesium1 besides other metals1 and an abundant supply of hydrogen gas4 ,,chapter ,,xxiv4 ,,different ,,kinds ,,of ,,suns4 ,various in kind1 various in size1 various in color1 various in position1 various in motion1 are the myriad suns scattered through space4 ,so far are they from being formed on the same plan1 turned out on the same model1 that it may with reason be doubted whether any two stars could be found exactly alike4 ,why should we expect to find them so8 ,no two oak-leaves1 no two elm-leaves1 precisely alike1 are to be found upon earth4 ,so some stars are large1 some are small4 ,some are rapid in movement1 some are slow4 ,some are yellow1 some white1 some red1 green1 blue1 purple1 or gray4 ,some are single stars2 others are arranged in pairs1 trios1 quartets1 or groups4 ,some appear only for a time1 and then disappear altogether4 ,others are changeful1 with a light that regularly waxes and wanes in brightness4 ,we have now to give a little time and thought to variable stars and temporary stars2 afterwards to double stars and colored stars4 ,there are many stars which pass through gradual and steady changes--first brightening1 then lessening in light1 then brightening again4 ,one such star is to be seen in the constellation of the ,whale4 ,it is named 8,mira10 or 8,the ,marvelous10 and the time in which its changes take place extends to eleven months4 ,for about one fortnight it is a star of the second magnitude4 ,through three months it grows slowly more and more dim1 till it becomes invisible1 not only to the naked eye1 but through ordinary telescopes4 ,about five months it remains thus4 ,then again1 during three months1 it grows brighter and brighter1 till it is once more a second-magnitude star1 and after a fortnight's pause begins anew to fade4 ,at its maximum1 this star is yellow2 when it is faint1 it is reddish4 ,spectrum analysis shows in it a striped spectrum of the third type1 and when its light diminishes it preserves all the principal bright rays reduced to very fine threads4 ,the most plausible explanation of this variability is to suppose that it periodically emits vapors similar to the eruptions observed in the solar photosphere4 ,instead of its periodicity being like that of the sun--eleven years and hardly perceptible--this variation of the sun of the ,whale is three hundred and thirty-one days and very considerable4 ,it is subject to oscillations and irregularities similar to those which we remark in our sun4 ,of all the variable stars1 this is the easiest to observe1 and it has been known for nearly three hundred years4 ,the most celebrated of all the variable stars is that known as ,algol1 in the constellation of ,perseus4 ,this star is very conveniently placed for observation1 being visible every night in the ,northern ,hemisphere1 and its wondrous and regular changes can be observed without any telescopic aid4 ,every one who desires to become acquainted with the great truths of astronomy should be able to recognize this star1 and should have also followed it during one of its periods of change4 ,algol is usually a star of the second magnitude2 but in a period between two or three days--or1 more accurately1 in an interval of two days1 twenty hours1 forty-eight minutes1 and fifty-five seconds--its brilliancy goes through a most remarkable cycle of variations4 ,the series commences with a gradual decline of the star's brightness1 which1 in the course of three or four hours1 falls from the second magnitude down to the fourth4 ,at this lowest stage of brightness1 ,algol remains for about twenty minutes1 and then begins to increase1 until in three or four hours it regains the second magnitude1 at which it continues for about two days1 thirteen hours1 when the same series commences anew4 ,it seems that the period required by ,algol to go through its changes is itself subject to a slow1 but certain variation4 ,another variable star1 ,betelgeuse in ,orion1 undergoes its variations in about two hundred days2 while yet another1 ,delta ,cephei1 takes only six days4 ,our own sun is believed to be in some slight degree a variable star1 passing through his changes in eleven years4 ,when the sun-spots are most numerous1 he would probably appear1 if seen from a great distance1 more dim than when there are few or none of them4 ,sometimes a star is not merely variable4 ,stars have appeared for a brief space1 and then utterly vanished4 ,they are then named ,temporary ,stars4 ,whether such a star really does go out of existence1 or whether it merely becomes too dim to be seen2 whether the furnace-fires are extinguished1 and the glowing sun changes into a dark body1 or whether it merely turns a dark side towards us for a very long period1--these are questions we can not answer4 ,an extraordinary specimen of a temporary star was seen in #aegb4 ,it was not a comet1 for it had no coma or tail1 and it never moved from its place4 ,the brightness of the star was so great as to surpass ,sirius and ,jupiter1 and to equal ,venus at her greatest brilliancy4 ,nay1 it must have surpassed even ,venus1 for it was plainly visible at midday in a clear sky4 ,gradually the light faded and grew more dim1 till at length it entirely disappeared4 ,as it lessened in brilliancy1 it also changed in color1 passing from white to yellow1 and from yellow to red4 ,this curiously agrees with the three tints of the first1 second1 and fourth orders of suns1 as lately classified4 ,this star was observed by ,tycho ,brahe1 who gives the following curious account3 8,one evening1 when ,i was contemplating1 as usual1 the celestial vault1 whose aspect was so familiar to me1 ,i saw1 with inexpressible astonishment1 near the zenith1 in ,cassiopeia1 a radiant star of extraordinary magnitude4 ,struck with surprise1 ,i could hardly believe my eyes4 ,to convince myself that it was not an illusion1 and to obtain the testimony of other persons1 ,i called out the workmen employed in my laboratory1 and asked them1 as well as all passers-by1 if they could see1 as ,i did1 the star1 which had appeared all at once4 ,i learned later on that in ,germany carriers and other people had anticipated the astronomers in regard to a great apparition in the sky1 which gave occasion to renew the usual railleries against men of science 7as with comets whose coming had not been predicted74 8,the new star was destitute of a tail2 no nebulosity surrounded it2 it resembled in every way other stars of the first magnitude4 ,its brightness exceeded that of ,sirius1 of ,lyra1 and of ,jupiter4 ,it could only be compared with that of ,venus when it is at its nearest possible to the earth4 ,persons gifted with good sight could distinguish this star in daylight1 even at noonday1 when the sky was clear4 ,at night1 with a cloudy sky1 when other stars were veiled1 the new star often remained visible through tolerably thick clouds4 ,the distance of this star from the other stars of ,cassiopeia1 which ,i measured the following year with the greatest care1 has convinced me of its complete immobility4 ,from the month of ,december1 #aegb1 its brightness began to diminish2 it was then equal to ,jupiter4 ,in ,january1 #aegc1 it became less brilliant than ,jupiter2 in ,february and ,march1 equal to stars of the first order2 in ,april and ,may1 of the brightness of stars of the second order4 ,the passage from the fifth to the sixth magnitude took place between ,december1 #aegc1 and ,february1 #aegd4 ,the following month the new star disappeared without leaving a trace visible to the naked eye1 having shone for seventeen months40 ,these circumstantial details permit us to imagine the influence which such a phenomenon must have exercised on the minds of men4 ,few historical events have caused so much excitement as this mysterious envoy of the sky4 ,it first appeared on ,november #aa1 #aegb4 ,general uneasiness1 popular superstition1 the fear of comets1 the dread of the end of the world1 long since announced by the astrologers1 were an excellent setting for such an apparition4 ,it was soon announced that the new star was the same which had led the wise men to ,bethlehem1 and that its arrival foretold the return of the ,messiah and the last judgment4 ,for the hundredth time1 perhaps1 this sort of prognostication was recognized as absurd4 ,it did not1 however1 prevent the astrologers from being believed1 twelve years later1 when they announced anew the end of the world for the year #aehh2 these predictions exercised the same influence on the public mind4 ,after the star of #aegb the most celebrated is that which appeared in ,october1 #afjd1 in ,serpentarius1 and which was observed by two illustrious astronomers1 ,kepler and ,galileo4 ,as happened with the preceding1 its light imperceptibly faded4 ,it remained visible for fifteen months1 and disappeared without leaving any traces4 ,in #afgj another temporary star1 blazing out in the head of the ,fox 7,vulpecula71 showed the singular phenomenon of being extinguished and reviving several times before it completely vanished4 ,we know of twenty-four stars which1 during the last two thousand years1 have presented a sudden increase of light2 have been visible to the naked eye1 often brilliant2 and have then again become invisible4 ,the last apparitions of this kind happened before our eyes in #ahff1 #ahgf1 #ahhe1 and #ahib1 and spectrum analysis enabled us to ascertain1 as we have seen1 that they were due to veritable combustion--a fire caused by a tremendous expansion of incandescent hydrogen1 and to phenomena analogous to those which take place in the solar photosphere4 ,a rather curious fact about these stars is1 that they do not blaze out indifferently in any point of the sky1 but in rather restricted regions1 chiefly in the neighborhood of the ,milky ,way4 ,many other instances have been known1 beside those referred to1 of variable and temporary stars4 ,there are two distinct kinds of double-stars4 ,first1 we have those which merely seem to be double1 because one lies almost directly behind the other1 though widely distant from it4 ,just as a church-tower1 two miles off1 may appear to stand close side by side with another church-tower two and a half miles off1 though they are in fact separated4 ,secondly1 we have the real systems of two suns belonging to one another2 the smaller moving round the larger1 or more correctly both traveling round one central point called the center of gravity1 the smaller having the quicker rate of motion4 ,illustration3 ,,lyra ,alpha ,centauri and #fa ,cygni have been already described1 as examples of true double-stars4 ,in the constellation ,lyra a marked instance is to be seen4 ,the brightest star in the ,lyre is ,vega1 and near ,vega shines a tiny star1 which to people with particularly clear sight has sometimes rather a longish look4 ,if you examine this star through an opera-glass1 you find it to consist of two separate stars4 ,but if you get a more powerful telescope1 and look again1 you will find that each star of the couple actually consists of two stars4 ,the four are not at equal distances4 ,two points of light seemingly close together are parted by a wide gap from two other points equally close together4 ,these four stars are believed to have a double motion4 ,each of the separate pairs revolves by itself1 the two suns traveling round one center2 and in addition to this the two couples of suns probably perform a long journey round another center common to them all4 ,many thousands of double stars have been discovered2 and a large number of these are now known to be1 not merely two distinct suns lying in the same line of sight1 but two brother-suns1 each probably the center of his own system of planets4 ,we have not only to consider the number of suns1 though of simple numbers more yet remains to be said4 ,attention must also be given to the varying colors of different stars2 for all suns in the universe are not made after the model of our sun4 ,all suns are not yellow4 ,so far as single stars are concerned1 colors seem rather limited4 ,white stars1 golden or orange stars1 ruby-red stars1 placed alone1 are often seen2 but blue stars1 green stars1 gray stars1 silver stars1 purple stars1 are seldom if ever visible to the naked eye1 or known to exist as single stars4 ,take a powerful telescope and examine star-couples1 and a very different result you will find4 ,not white1 yellow1 and red alone1 but blue1 purple1 gray1 green1 fawn1 buff1 silvery white1 and coppery hues1 will delight you in turn4 ,as a rule1 when the two stars of a couple are alike in color1 they are either white1 or yellow1 or red4 ,also in the case of double-stars of different colors1 the larger of the two is almost invariably white or some shade of yellow or red4 ,there are1 however1 exceptions to all such rules4 ,blue stars are almost never seen alone1 and as one of a pair the blue star is generally1 if not invariably1 the smaller4 ,but instances are known of double-stars1 both of which are blue2 and one group in the southern heavens is entirely made up of a multitude of bluish suns4 ,it is when we come to consider double-stars of two colors that the most striking effects are found4 ,now and then the two suns are nearly the same in size2 but more commonly one is a good deal larger than the other4 ,this is known by the brighter light of the largest1 and the more rapid movements of the smallest4 ,the lesser star is often only small by comparison1 and may be in reality a very goodly and brilliant sun4 ,among nearly six hundred 8doubles0 examined by one astronomer1 there were three hundred and seventy-five in which the two stars were of one color1 generally white1 yellow1 orange1 or red4 ,the rest were different in tint1 the difference between the two suns in about one hundred and twenty cases being very marked4 ,for instance1 a red 8primary10 as the larger star is called1 will be seen with a small green satellite2 or a white primary will have a little brother-sun of purple1 or of dark ruby1 or of light red4 ,sometimes the larger sun is orange1 the companion being purple or dark blue4 ,again1 the chief star will be red with a blue satellite1 or yellow with a green satellite1 or orange with an emerald satellite1 or golden with a reddish-green satellite4 ,we hear of golden and lilac couples1 of cream and violet pairs1 of white and green companions4 ,but1 indeed1 the variety is almost endless4 ,illustration3 ,,constellations ,,in ,,the ,,northern ,,hemisphere4 ,there may be worlds circling around these suns--worlds1 perhaps1 with living creatures on them4 ,we know little about how such systems of suns and worlds may be arranged4 ,probably each sun would have his own set of planets1 and both suns with their planets would travel round one central point4 ,perhaps1 where the second sun is much the smallest1 it might occasionally be like a big blazing satellite among the planets--a kind of burning ,jupiter-sun to the chief sun4 ,among colored stars1 single and double1 a few may be mentioned by name as examples4 ,sirius1 as already observed1 is a brilliant white sun2 and brilliant white also are ,vega1 ,altair1 ,regulus1 ,spica1 and many others4 ,capella1 ,procyon1 the ,pole-star1 and our own sun1 are examples of yellow stars4 ,aldebaran1 ,betelgeuse1 and ,pollux1 are ruby-red4 ,antares is a red star1 with a greenish 8scintillation0 or change of hue in its twinkling4 ,a tiny green sun belonging to this great and brilliant red sun has been discovered4 ,some have called ,antares 8the ,sirius of ,red ,suns40 ,it is during the fine nights of winter that the constellation ,taurus1 or ,the ,bull1 with the star ,aldebaran marking its eye1 shines in the evening above our heads4 ,no other season is so magnificently constellated as the months of winter4 ,while nature deprives us of certain enjoyments in one way1 it offers us in exchange others no less precious4 ,the marvels of the heavens present themselves from ,taurus and ,orion in the east to ,virgo and ,botes on the west4 ,of eighteen stars of the first magnitude1 which are counted in the whole extent of the firmament1 a dozen are visible from nine o'clock to midnight1 not to mention some fine stars of the second magnitude1 remarkable nebul1 and celestial objects well worthy of the attention of mortals4 ,it is thus that nature establishes an harmonious compensation1 and while it darkens our short and frosty days of winter1 it gives us long nights enriched with the most opulent creations of the sky4 ,the constellation of ,orion is not only the richest in brilliant stars1 but it conceals for the initiated treasures which no other is known to afford4 ,we might almost call it the ,california of the sky4 ,to the southeast of ,orion1 on the line of the ,three ,kings1 shines the most magnificent of all the stars1 ,sirius1 or ,alpha of the constellation of the ,great ,dog4 ,this constellation rises in the evening at the end of ,november1 passes the meridian at midnight at the end of ,january1 and sets at the end of ,march4 ,it played the greatest part in ,egyptian astronomy1 for it regulated the ancient calendar4 ,it was the famous ,dog ,star2 it predicted the inundation of the ,nile1 the summer solstice1 great heats and fevers2 but the precession of the equinoxes has in three thousand years moved back the time of its appearance by a month and a half2 and now this fine star announces nothing1 either to the ,egyptians who are dead or to their successors4 ,but we shall see farther on what it teaches us of the grandeur of the sidereal universe4 ,the ,little ,dog1 or ,procyon1 is found above the ,great ,dog and below the ,twins 7,castor and ,pollux71 to the east of ,orion4 ,with the exception of ,alpha ,procyon1 no brilliant star distinguishes it4 ,the two double-stars1 #fa ,cygni and ,alpha ,centauri1 are formed each of two orange suns4 ,in the ,southern ,cross there is a wonderful group of stars1 consisting of about one hundred and ten suns1 nearly all invisible to the naked eye4 ,among the principal stars of this group1 which ,sir ,john ,herschel described as being1 when viewed through a powerful telescope1 like 8a casket of variously-colored precious stones10 are two red stars1 two bright green1 three pale green1 and one of a greenish blue4 ,the splendor of these natural illuminations can hardly be conceived by our terrestrial imagination4 ,the tints which we admire in these stars from here can give but a distant idea of the real value of their colors4 ,already1 in passing from our foggy latitudes to the limpid regions of the tropics1 the colors of the stars are accentuated1 and the sky becomes a veritable casket of brilliant gems4 ,what would it be if we could transport ourselves beyond the limits of our atmosphere8 ,seen from the moon1 these colors would be splendid4 ,antares1 ,alpha ,herculis1 ,pollux1 ,aldebaran1 ,betelgeuse1 ,mars1 shine like rubies2 the ,polar ,star1 ,capella1 ,castor1 ,arcturus1 ,procyon1 are veritable celestial topazes2 while ,sirius1 ,vega1 and ,altair are diamonds1 eclipsing all by their dazzling whiteness4 ,how would it be if we could approach the stars so as to perceive their luminous disks1 instead of merely seeing brilliant points destitute of all diameter8 ,blue days1 violet days1 dazzling red days1 livid green days6 ,could the imagination of poets1 could the caprice of painters1 picture on the palette of fancy a world of light more astounding than this8 ,could the mad hand of the chimera1 throwing on the receptive canvas the strange lights of its fancy1 erect by chance a more astonishing edifice8 ,,chapter ,,xxv4 ,,groups ,,and ,,clusters ,,of ,,suns4 ,we have been thinking a good deal about single stars and double stars1 as seen from earth4 ,now we have to turn our attention to groups1 clusters1 masses of stars1 in the far regions of space4 ,have you ever noticed on a winter night1 when the sky was clear and dotted with twinkling stars1 a band of faintly-glimmering light stretching across the heavens from one horizon to the other8 ,the band is irregular in shape1 sometimes broader1 sometimes narrower2 here more bright1 there more dim4 ,if you were in the ,southern ,hemisphere you would see the same soft belt of light passing all across the southern heavens4 ,this band or belt is called the ,milky ,way4 ,but what is the ,milky ,way8 ,it is made up of stars4 ,so much we know4 ,as the astronomer turns his telescope to the zone of faintly-gleaming light1 he finds stars appearing behind stars in countless multitudes2 and the stronger his telescope1 the more the white light changes into distant stars4 ,our sun we believe to be one of the stars of the ,milky ,way2 merely one star among millions of stars2 merely one golden grain among the millions of sparkling gold-dust grains scattered lavishly through creation4 ,scattered1 not recklessly1 not by chance1 but placed1 arranged1 and guided each by its ,maker's upholding hand4 ,the ,milky ,way1 or the ,galaxy1 as it has been called1 has great interest for astronomers4 ,many have been the attempts made to discover its actual size1 its real shape1 how many stars it contains1 how far it extends2 but to all such questions the only safe answers to be returned are fenced around with 8perhaps0 and 8may be40 ,there are many very remarkable clusters of stars to be seen in the heavens--some few visible as faint spots of light to the naked eye1 though the greater number are only to be seen through a telescope4 ,either with the naked eye1 or in telescopes of varying power1 they show first as mere glimmers of light1 which1 viewed with a more powerful telescope1 separate into clusters of distant stars4 ,illustration3 ,a ,,cluster ,,of ,,stars ,,in ,,centaurus4 ,the most common shape of these clusters is globular--to the eye appearing simply round4 ,stars gather densely near the center1 and gradually open out to a thin scattering about the edge4 ,thousands of suns are often thus collected into one cluster4 ,the clusters are to be seen in all parts of the sky2 but the greater number seem to be gathered into the space covered by the ,milky ,way and by the famous south ,magellanic ,clouds4 ,some of them are beautifully colored2 as1 for instance1 a cluster in ,toucan1 not visible from ,england1 the center of which is rose-colored1 bordered with white4 ,no doubt it contains a large number of bright red suns1 surrounded by a scattering of white suns4 ,it used to be supposed that many of these clusters were other vast gatherings or galaxies of stars1 like the ,milky ,way1 lying at enormous distances from us4 ,this now seems unlikely4 ,the present idea rather is1 that each cluster1 in place of being another 8,milky ,way0 of millions of widely-scattered suns1 is one great star-system1 consisting indeed of thousands of suns1 but all moving round one center4 ,probably most of these clusters are themselves a part of the collection of stars to which our sun belongs4 ,if this be so1 and if worlds are traveling among the suns--as may well be1 since they are doubtless quite far enough apart for each sun to have his own little or great system of planets--what sights must be seen by the inhabitants of such planets6 ,we do not indeed know the distance between the separate suns of a cluster1 which may be far greater than appears to us4 ,but if astronomers calculate rightly1 they are near enough together to shed bright light on all sides of a planet revolving in their midst4 ,the said planet might perhaps not have within view a single sun equal in apparent size to our sun as seen from earth2 yet thousands of lesser suns1 shining brightly in the firmament night and day1 would cause a radiance which we never enjoy4 ,no1 not night4 ,in such a world there could be no night4 ,worlds in the midst of a star-cluster must be regions of perpetual day4 ,no night1 no starry heaven1 no sunrise lights or sunset glories1 no shadow mingling with sunshine1 but one continual1 ceaseless blaze of brightness4 ,we can hardly picture1 even in imagination1 such a condition of things4 ,illustration3 ,,the ,,great ,,nebula ,,in ,,andromeda1 ,,compared ,,with ,,size ,,of ,,the ,,solar ,,system4 ,besides star-clusters there are also nebul4 ,the word nebula comes from the ,latin word for 8cloud10 and the nebul are so named from their cloudlike appearance4 ,it is not easy to draw a line of clear division between nebul and distant star-clusters2 for both have at first sight the same dim1 white1 cloudy look4 ,in past days the star-clusters were included by astronomers under the general class of nebul4 ,and as with the star-clusters1 so with many of the nebul1 the more powerful telescopes of modern days have shown them to be great clusters1 or systems1 or galaxies of stars1 at vast distances from us4 ,it was supposed with the nebul1 as with some of the star-clusters1 that they were other 8,milky ,ways0 of countless stars1 far beyond the outside boundaries of our ,milky ,way4 ,this may still be true of some or many nebul1 but certainly not of all4 ,for there are different kinds of nebul4 ,some may1 as just said1 be vast gatherings of stars lying at distances beyond calculation1 almost beyond imagination4 ,others appear rather to be clusters of stars1 like those already described1 probably situated in our own galaxy of stars4 ,there is also a third kind of nebula4 ,many nebul1 once supposed to be clusters of stars1 having been lately examined by means of the spectroscope1 are found to be enormous masses of glowing gas1 and not solid bodies at all4 ,the number of nebul known amounts to many thousands4 ,they are commonly divided into classes1 according to their seeming shape4 ,there are nebul of regular form1 and nebul of irregular form4 ,there are circular nebul1 oval nebul1 annular nebul1 conical nebul1 cometary nebul1 spiral nebul1 and nebul of every imaginable description4 ,these shapes would no doubt entirely change1 if we could see them nearer2 and indeed1 even in more powerful telescopes1 they are often found to look quite different4 ,while on the subject of clusters and nebul1 mention should be made of the famous ,magellanic ,clouds in the southern heavens4 ,sometimes they are called the ,cape ,clouds4 ,they differ from other nebul in many points1 and more particularly in their apparent size4 ,the ,great ,cloud is about two hundred times the size of the full moon1 while the ,small ,cloud is about one-quarter as large4 ,in appearance they are not unlike two patches of the ,milky ,way1 separated and moved to a distance from the main stream4 ,these clouds are surrounded by a very barren portion of the heavens1 containing few stars2 but in themselves they are peculiarly rich4 ,seen through a powerful telescope1 they are found to abound with stars4 ,the ,greater ,cloud alone contains over six hundred from the seventh to the tenth magnitudes1 countless tiny star-points of lesser magnitudes1 star-clusters of all descriptions1 and nearly three hundred nebul1--all crowded into this seemingly limited space4 ,among many famous nebul1 the one in ,orion and the one in ,andromeda may be particularly mentioned4 ,the size of the latter1 as compared with the size of our ,solar ,system1 is shown in the cut of this nebula4 ,on the hypothesis of a complete resolvability into stars1 the mind is lost in numbering the myriads of suns1 the agglomerated individual lights of which produce these nebulous fringes of such different intensities4 ,what must be the extent of this universe1 of which each sun is no more than a grain of luminous dust6 ,,chapter ,,xxvi4 ,,the ,,problem ,,of ,,sun ,,and ,,star ,,distances4 ,one question had long occupied the minds of scientific men without the finding of any satisfactory answer1 and this was the distance of the sun from our earth4 ,at length the sun had fully gained his rightful position in the minds of men as center and controller of the ,solar ,system1 and earth was fully dethroned from her old false position4 ,in point of fact1 the sun had gained more than his rightful position2 since he was now looked upon very much as the earth had been formerly looked upon2 since he was regarded practically as the motionless ,universe-,center4 ,the earth might and did move--people had grown used to that idea--but the sun1 at all events1 was fixed4 ,the sun1 beyond turning upon his axis1 was motionless4 ,still1 as to the true distance of the sun from ourselves1 ignorance reigned4 ,tycho ,brahe had made a great advance on earlier notions by placing the light-giver #d1jjj1jjj miles away in imagination4 ,kepler1 a quarter of a century later1 increased this to #ad1jjj1jjj4 ,galileo afterwards reverted to the #d1jjj1jjj4 ,all this1 however1 was sheer guesswork4 ,not till well on in the seventeenth century did ,cassini make a definite attempt at actual measurement of the sun's distance1 and this attempt gave as a result some #hb1jjj1jjj miles--not far removed from the truth4 ,but at the same period other observers gave results of #da1jjj1jjj and #acf1jjj1jjj2 so for years the question still remained swathed in mist4 ,better modes and better instruments were required before it could receive settlement4 ,the measurement of the distance of objects a good way off is by means of their 8parallax10 or the apparent change in their position when viewed from two different points at some distance from each other4 ,to this method of calculating distance we have already referred4 ,this kind of measurement of distances is not confined to our earth's surface alone4 ,the distances of bright bodies in the heavens may be calculated after just the same method1 provided only that the heavenly body is not too far distant to be made to change its seeming position in the sky4 ,suppose you wished to find out how far off the moon is4 ,you would have to make your observation of the moon's exact position in the sky--of just that spot precisely where she is to be seen among heavenly scenery at a particular moment2 and you would have to get somebody else to make a similar observation1 at the same time1 from some other part of earth1 at a good distance from your post4 ,there are no hills or woods in the sky for the moon to be seen against2 but there are plenty of stars1 bright points of light far beyond the moon4 ,if you look at her from one place1 and your friend looks at her from another place a good way off1 there will be a difference in your two 8views40 ,you will see her very close to certain stars2 and your friend will see her not quite so close to those stars1 but closer to others4 ,this difference of view would give the moon's parallax4 ,if your observation were very careful1 very exact1 and if you had the precise distance between the spot where you stood1 and the spot where your friend stood1--then1 from that base-line1 and from the two angles formed by its junction with the lines from the two ends of it straight to the moon1 you might reckon how many miles away the moon is4 ,the greater the distance between the two places of observation1 the better1--as1 for instance1 at ,greenwich and the ,cape of ,good ,hope4 ,practically1 this is not nearly so simple a matter as it may sound1 because our earth is always on the move1 and the moon herself is perpetually journeying onward4 ,all such motions have to be most scrupulously allowed for4 ,so the actual measurement of moon-distance requires a great deal of knowledge and of study4 ,many other difficulties and complications besides these enter into the question1 and have to be overcome4 ,now1 the sun is very much farther away than the moon1 and the stumbling-blocks in the way of finding out his distance become proportionately greater and more numerous4 ,to observe him from two parts of ,england1 or from two parts of ,europe1 would give him no parallax4 ,that is to say1 there would be no change of position on his part apparent to us4 ,i do not say that there would be no change at all2 but only that it would be so minute as to be quite unseen by human eyes1 even with the help of most careful and accurate measurement4 ,a very long base-line is needed to make the sun distinctly appear to change his position ever so little4 ,only the very longest base-line which can be found on earth will do for this1--nothing less than the earth's whole diameter of nearly eight thousand miles4 ,and ,i think you will see that the success of the calculation would then depend1 not alone on most careful observation from two posts at the opposite sides of earth2 not alone on mathematical gifts and powers of close reckoning2 but also1 essentially1 on a true knowledge of our earth's diameter2 that is1 of the exact length of the base-line from which the whole calculation would have to be made1 and upon which the answer would largely depend4 ,for a long while the earth's diameter was not well known4 ,as time went on1 fresh measurements were again and again made of different portions of earth's surface1 fresh calculations following therefrom2 and gradually clear conclusions were reached4 ,a very important matter it was that they should be reached2 for the semi-diameter of our earth has been adopted as a 8standard measure0 for the whole universe2 and the slightest error in that standard measure would affect all after calculations4 ,when actual observations of sun-distance came to be made1 innumerable difficulties arose4 ,foremost stood the huge amount of that distance4 ,this made precise observations more difficult2 and at the same time it made every mistake in observation so much the worse4 ,a little mistake in observing the moon might mean only a hundred miles or so wrong in the answer2 but a mistake equally small in observing the sun would lead to an error of many millions of miles4 ,again1 to observe the sun's exact position among the stars1 as with the moon1 was not possible2 because when the sun is visible1 the stars are not visible4 ,then1 too1 the dazzling brightness of the sun balked the needed exactitude4 ,halley had a brilliant thought before he died4 ,he could not carry it out himself1 but he left it to others as a legacy2 that was1 by observing the transit of ,venus from two different points on the earth's surface4 ,at his suggestion1 on the first opportunity--which was not till after his death--the above mode was tried of measuring the sun's distance4 ,a certain observer1 stationed on one part of earth1 saw the tiny dark body of ,venus take one particular line across the sun's bright face4 ,another observer1 standing on quite another and a far-off part of earth1 saw the little dark body take quite another line across the sun's bright face4 ,not that there were two little dark bodies1 but that the one body was seen by different men in different places4 ,from these separate views of the path of ,venus across the face of the sun1 in connection with what was already known of the earth's diameter1 and therefore of the length of base-line between the two places1 the distance of the sun was reckoned to be about #ie1jjj1jjj miles4 ,since that date many fresh attempts have been made1 and errors have been set right4 ,mercury as well as ,venus has been used in this matter1 and other newer modes of measurement have also been successfully tried4 ,we know now1 with tolerable accuracy1 that the sun's greater distance from earth is between #ib1jjj1jjj and #ic1jjj1jjj miles4 ,a curious illustration of sun-distance has been offered by one writer4 ,sound and light1 heat and sensation1 all require time for journeying4 ,when a child puts his finger into a candle-flame1 he immediately shrieks with pain4 ,yet1 quickly as the cry follows the action1 his brain is not really aware of the burn until a certain interval has elapsed4 ,true1 the interval is extremely minute2 still it is a real interval4 ,news of the burn has to be telegraphed from the finger1 through the nerves of the arm1 up to the brain2 and it occupies time in transmission1 though so small a fraction of a second that we can not be conscious of it4 ,now1 try to imagine a child on earth with an arm long enough to reach the sun4 ,his fingers might be scorched by the raging fires there1 while yet his brain on earth would remain quite unaware of the fact for about one hundred and thirty years4 ,all through those years1 sensation would be darting along the arm exactly as fast as it darts from the finger-tips of an ordinary child on earth to that child's brain4 ,if the scorching began before he was one year old1 he would have become a very aged man1 one hundred and thirty years old1 before he could know in his mind what was happening in the region of his hand4 ,moreover1 if1 on receiving the intimation1 he should decide to withdraw his hand from that unpleasantly-hot neighborhood1 another hundred and thirty years would elapse before the fingers could receive and act upon the message1 telegraphed from the brain1 through the nerves of the arm4 ,so much for the distance of the sun from our earth6 ,but the stars6 ,how far off are the stars8 ,the distance of the moon is a mere nothing4 ,the distances of the planets have been found out4 ,the distance of the sun has been measured4 ,but the stars--those wondrous points of light1 twinkling on1 night after night1 century after century1 unchanged in position save by the seeming nightly pilgrimage of them all across the sky in company1 caused only by our earth's restless1 continual whirl1-- ,what about the distances of the stars8 ,can we measure their distance by means of their parallax8 ,this mode of measurement was tried successfully on the moon1 on the planets1 and on the sun4 ,but when it was tried upon the stars1 from two stations as far apart as any two stations on earth could be1 the attempt was a failure4 ,not a ghost of parallax could be detected with any one star4 ,not the faintest sign of displacement was seen in the position of a single star when most critically and carefully examined4 ,then arose a brilliant thought6 ,what of earth's yearly journey round the sun8 ,if a base-line of #h1jjj miles were not enough1 compared with the great distance of the stars1 this at least remained4 ,our earth at midsummer is somewhere about #ahe1jjj1jjj miles away from where she is at midwinter1 comparing her position with that of the sun1 and reckoning him to be at rest4 ,in reality1 the sun is not at rest1 but is in ceaseless motion1 carrying with him1 wherever he goes1 the whole ,solar ,system with as much ease as a train carries its passengers4 ,those passengers are truly in motion1 yet1 with regard merely to the train1 they are at rest4 ,so each member of the ,solar ,system--attached to the sun1 not by ,ptolemaic bars1 but by the bond of gravity--is borne along by him through space2 yet1 with respect to each member of that system1 the central sun is always and absolutely at rest4 ,at one time of the year1 our earth is on one side of the sun1 over #ib1jjj1jjj miles distant4 ,six months later1 the earth is on the other side of the sun1 not quite #ic1jjj1jjj miles away from him in that opposite direction4 ,twice #ic1jjj1jjj comes to #ahf1jjj1jjj4 ,this line1 therefore--the diameter of the earth's whole yearly orbit1 may be roughly stated as about #ahe1jjj1jjj of miles in length4 ,here surely was a base-line fit to give parallax to any star--or1 rather1 to make parallax visible in the case of any star4 ,for it is1 after all1 a question1 not of fact1 but of visibility2 not of whether the thing is1 but of whether we are able to see it4 ,as the earth journeys on her annual tour round the sun1 following a slightly elliptic pathway1 the diameter of which is about #ahe1jjj1jjj miles1 each star in the sky must of necessity undergo a change of position1 however minute1 performing a tiny apparent annual journey in exact correspondence with the earth's great annual journey4 ,the question is not1 ,does the star do this8 but1 ,can we see the star do this8 ,its apparent change of position may be so infinitesimal1 through enormous distance1 that no telescopes or instruments yet made by man can possibly show it to us4 ,the star-motion of which ,i am now speaking is purely a seeming movement1 not real4 ,be very clear on this point in your mind4 ,real star-movements1 though suspected earlier1 were not definitely surmised--one may even say 8discovered0--until the year #agah1 by ,halley4 ,and though ,cassini in #agbh referred to this discovery of ,halley's1 yet very little was heard about the matter until the days of ,herschel4 ,only apparent star-motions were generally understood and accepted4 ,the first and simplest of such seeming star-motions is one which we can all see--the nightly journey of the whole host of stars1 caused by our earth's whirl upon her axis4 ,the second is also simple1 but by no means also easily seen4 ,astronomers reasoned out the logical necessity for such an apparent motion long before it could be perceived4 ,as far back as the days of ,copernicus it was felt that if the ,copernican ,system were true1 if the earth in very deed traveled round the sun1 then the stars ought to change their positions in the sky when viewed from different parts of earth's annual journey4 ,observations were taken1 divided by six months of time and by one hundred and eighty-five millions of miles of space4 ,and the stars stirred not6 ,stupendous as was this base-line1 it proved insufficient4 ,so much more stupendous was the distance of the stars that the base-line sank to nothing1 and once again parallax could not be detected4 ,not that the seeming change of position in the star did not take place1 but that human eyes were unable to see it1 human instruments were unable to register it4 ,there lies the gist of the matter4 ,if the change of position can be observed1 well and good6 ,the length of the base-line being known1 the distance of the star may be mathematically calculated4 ,for the size of the tiny apparent path1 followed in a year by the star1 is and must be exactly proportioned to the distance of the star from that base-line4 ,if the tiny oval be so much larger1 then the star is known to be so much nearer4 ,if the tiny oval be so much smaller1 then the star is known to be so much farther away4 ,but when not the minutest token could be discovered of a star's position in the sky being in the least degree affected by the earth's great annual change of position1 astronomers were at a loss4 ,there was absolutely nothing to calculate from4 ,the star was a motionless point to earth4 ,the whole yearly orbit of earth was a motionless point to the star4 ,one slender beam of light united the two4 ,reckoners had nothing to stand upon4 ,it is interesting to know that ,copernicus had actually1 long before1 suggested this as a possible explanation of the absence of star-parallax4 ,he thought that astronomers might fail altogether to find it1 because the stars might be 8at a practically infinite distance0 from our earth4 ,,chapter ,,xxvii4 ,,measurement ,,of ,,star ,,distances4 ,until the days of ,sir ,william ,herschel1 little attention was bestowed upon the universe of distant stars4 ,before his advent the interest of astronomers had been mainly centered in the sun and his revolving worlds4 ,the 8fixed stars0 were indeed studied1 as such1 with a certain amount of care1 and numberless efforts were made to discover their distances from earth2 but the thought of a vast ,starry ,system1 in which our little ,solar ,system should sink to a mere point by comparison with its immensity1 had not yet dawned4 ,with larger and yet larger telescopes of his own making1 ,herschel studied the whole ,solar ,system1 and especially the nature of sun-spots1 the rings of ,saturn1 the various motions of attendant moons1 together with countless other details4 ,he enlarged the system by the discovery of another planet outside ,saturn--the planet ,uranus1 till then unknown4 ,these were only first steps4 ,the work which he did in respect of the ,solar ,system was as nothing compared with the work which he did among the stars4 ,his work in our system was supplementary to other men's labors2 his work among the stars was the beginning of a new era4 ,like many before him1 he1 too1 sought eagerly to find star-parallax1 and he1 too1 failed4 ,not yet had instruments reached a degree of finish which should permit measuring operations of so delicate a nature4 ,although he might not detect star-parallax1 he sprang a mine upon the older notions of star-fixity4 ,he shook to its very foundations the sidereal astronomy of the day1--the theory1 long held1 of a motionless universe1 motionless stars1 and a rotating but otherwise motionless sun4 ,he did away with the mental picture1 then widely believed in1 of vast interminable fixity and stillness1 extending through space1 varied only by a few little wandering worlds4 ,as he swept the skies1 and endeavored to gauge the fathomless depths1 and vainly pursued the search for the parallax of one star after another1 he made a great and unlooked-for discovery4 ,this was in connection with double-stars4 ,double-stars had long been known1 and were generally recognized4 ,but whether the doubleness were purely accidental1 due merely to the fact of two stars happening to lie almost in the same line of sight1 as viewed from earth1 or whether any real connection existed between the two1 no man living could say4 ,indeed1 so long as all stars were regarded as utter fixtures1 the question was of no very great interest4 ,but light dawned as ,herschel watched4 ,he found the separate stars in a certain pair to be moving4 ,each from time to time had slightly1 very slightly1 changed its place4 ,then1 at least1 if all other stars in the universe were fixed1 those two were not fixed4 ,he watched on1 and gradually he made out that their motions were steady1 were systematic1 and were connected the one with the other4 ,that was one of the first steps towards breaking down the olden notion1 so widely held1 of a fixed and unchanging universe4 ,another double-star1 and yet another1 responded to ,herschel's intense and careful searching4 ,these other couples1 too1 were revolving1 not separately1 but in company2 journeying together round one center2 bound together apparently by bonds of gravitation1 even as our sun and his planets are bound together4 ,other stars besides binary stars are found to move with a real and not merely a seeming movement4 ,viewed carelessly1 the stars do indeed appear to remain fixed in changeless groups2 fixed even through centuries4 ,but1 to exceedingly close watching and accurate measurement1 many among them are distinctly not fixed2 many among them can be actually seen to move4 ,of course the observed motions are very small and slow4 ,one may be found to creep over a space as wide as the whole full moon in the course of three hundred or four hundred years2 and this is rapid traveling for a star in earth's sky6 ,another will perhaps cross a space one-tenth or one-twentieth or one-fiftieth of the moon's width in one hundred years4 ,such motions had never been carefully noted or examined1 until ,herschel came to do away with the old received notions of star-fixity4 ,happily1 ,herschel was no slave to 8received ideas40 ,like ,galileo in earlier times1 he wished to 8prove all things0 personally1 anxious only to find out what was the truth4 ,and he found that the stars were not fixed6 ,he found that numbers of them were moving4 ,he conjectured that probably all the rest were moving also2 that in place of a fixed universe of changeless stars we have a whirling universe of rushing suns4 ,herschel could not1 of course1 watch any one star for a hundred years1 much less for several centuries4 ,but in a very few years he could1 by exceedingly close measurement1 detect sufficient motion to be able to calculate how long it would take a certain star to creep across a space as wide as the full moon4 ,from step to step he passed on1 never weary of his toil4 ,he sought to gauge the ,milky ,way1 and to form some notion of its shape4 ,he noted a general drift of stars to right and to left1 which seemed to speak of a possible journey of our sun through space1 with all the planets of the ,solar ,system4 ,he flung himself with ardor into the study of star-clusters and of nebul4 ,he saw1 with an almost prophetic eye1 the wondrous picture of a developing universe--of nebul growing slowly into suns1 and of suns cooling gradually into worlds--so far as to liken the heavens to a piece of ground1 containing trees and plants in every separate stage of growth4 ,and still the search for star parallax went on1 so long pursued in vain4 ,no longer base-line than that of the diameter of earth's yearly orbit lay within man's reach4 ,but again and yet again the attempt was made4 ,instruments were improved1 and measurements became ever more delicate2 and at length some small success crowned these persistent endeavors4 ,the tiny sounding-line of earth1 lowered so often into the mysterious depths of space1 did at last 8touch bottom40 ,herschel died1 full of years and honors1 in #ahbb2 and some ten years later three different attempts proved1 all to some extent1 and almost at the same date1 successful4 ,bessel1 however1 was actually the first in point of time2 and his attempt was upon the double-star1 #fa ,cygni2 not at all a bright star1 but only just visible to the naked eye4 ,there are stars and stars1 enough to choose from4 ,the difficulty always was1 which to select as a subject for trial with any reasonable prospect of a good result4 ,some astronomers held that the brightest stars were the most hopeful1 since they were probably the nearest2 and of course the nearer stars would show parallax more readily1 because their parallax would be the greater4 ,but certain very bright stars indeed are now known to be far more distant than certain very dim stars4 ,again1 some astronomers thought that such stars as could be perceived to move most rapidly in the course of years would be the most hopeful objects to attack1 since the more rapid movement might be supposed to mean greater nearness1 and so greater ease of measurement4 ,but some stars1 seen to move rapidly1 are now known to be more distant than others which are seen to move more sluggishly4 ,so neither of these two rules could altogether be depended on2 yet both were1 on the whole1 the best that could be followed1 either separately or together4 ,the star #fa ,cygni is not one of the brighter stars1 but it is one of those stars which can be seen to travel most quickly across the sky in the course of a century4 ,therefore it was selected for a trial2 and that trial was the first to meet with success4 ,for #fa ,cygni was found to have an apparent parallax2 in other words1 its tiny seeming journey through the year1 caused by our earth's great journey round the sun1 could be detected4 ,small as the star-motion was1 it might1 through careful measurement1 be perceived4 ,and1 in consequence1 the distance of the star from earth could be measured4 ,not measured with anything like such exactitude as the measurements of sun-distance1 but with enough to give a fair general notion of star-distance4 ,one success was speedily followed by others4 ,by a few others1--not by many4 ,among the thousands of stars which can be seen by the naked eye1 one here and one there responded faintly to the efforts made4 ,one here and one there was found to stir slightly in the sky1 when viewed from earth's summer and winter positions1 or from her spring and autumn positions1 in her yearly pathway round the sun4 ,it was a very1 very delicate stir on the part of the star4 ,somewhat like the difference in position which you might see in a penny a few miles off1 if you looked at it first out of one window and then out of another window in the same house4 ,you may picture the penny as radiantly bright1 shining through pitch darkness2 and you may picture yourself as looking at it through a telescope4 ,but even so1 the apparent change of position in the penny1 viewed thus1 would be exceedingly minute1 and exceedingly difficult to see4 ,there are two ways of noting this little seeming movement on the part of a star in the sky4 ,either its precise place in the sky may be observed--its exact position1 as in a map of the heavens--or else its place may be noted as compared with another more distant star1 near to it in the sky1 though really far beyond4 ,parallax1 if visible1 would make it alter its precise place in the sky4 ,parallax1 if visible1 would bring it nearer to or farther from any other star more distant than itself from earth4 ,the more distant star would have a much smaller parallax--probably so small as to be invisible to us--and so it would do nicely for a 8comparison star40 ,the first of these methods was the first tried2 and the second was the first successful4 ,to find star-distance through star-parallax sounds quite simple1 when one thinks of the general principle of it4 ,just merely the question of a base-line1 accurately measured2 and of two angles1 accurately observed2 and of another angle1 a good way off1 accurately calculated1--all resting on the slight seeming change of position in a certain distant object1 watched from two different positions1 about #ahe1jjj1jjj miles apart4 ,quite simple1 is it not8 ,only1 when one comes to realize that the 8change of position0 is about equal to the change of position in a penny piece1 miles away1 looked at from two windows in one house1--then the difficulty grows4 ,besides this1 one has to remember all the 8corrections0 necessary1 before any true result can be reached4 ,a penny piece1 miles away1 seen from two windows1 would be difficult enough as a subject for measurement4 ,but1 at least1 the penny would be at rest2 and you yourself would be at rest2 and light would pass instantaneously from it to you2 and there would be no wobbling and nodding motions of everything around to add to your perplexities4 ,in the measurement of star-parallax1 all these things have to be considered and allowed for2 all have to be put out of the question1 as it were1 before any correct answer is obtained4 ,the refraction of light must be considered2 because that displaces the star1 and makes it seem to us to be where it is not4 ,and the aberration of light must be considered2 because1 in a different way1 that does the same thing1 making the star seem to take a little journey in the course of the year4 ,and the precession1 or forward motion1 of the equinoxes1 and nutation1 or vibratory motion1 have both to be separately considered2 because they1 too1 affect the apparent position of every star in the sky4 ,to watch the star in comparison with another star is easier than merely to note its exact position in the sky2 for the other star--the 8companion-star0--is equally with itself affected by refraction of light and by aberration of light4 ,but1 then1 another question comes in seriously3 whether or no the companion-star shows any parallax also2 since1 if it does1 that parallax must be carefully calculated and allowed for4 ,so the measurement of star-distance1 even when parallax can be detected1 is by no means a light or easy matter4 ,on the contrary1 it bristles with difficulties4 ,it is a most complicated operation1 needing profound knowledge1 accurate observation1 trained powers of reasoning and calculation4 ,nothing short of what has been termed 8the terrific accuracy0 of the present day could grapple with the truly tremendous difficulties of this problem of star-distance4 ,it has1 however1 been grappled with1 and grappled with successfully4 ,we now know1 not indeed with anything like exactitude1 yet with reasonable certainty1 the distances of a good many stars1 as expressed roughly in round number of 8about0 so many trillions of miles4#c ,we have at least learned enough to gain some notion of the immeasurable distances of countless other stars1 lying far beyond reach of earth's longest measuring-line4 #c ,the diameter of the moon as seen from the earth is equal to one thousand eight hundred and sixty eight seconds of space4 ,when the parallax of a star is ascertained1 it is a simple matter to calculate the distance of the star by the use of the following table4 ,if the star shows a displacement of one second in space1 or one eighteen-hundred-and-sixty-eighth part of the width of the moon1 that star is distant two hundred and six thousand two hundred and sixty-five times the distance of the earth from the sun4 ,an angle of #a is equivalent to #bjf1bfe times #ic1jjj1jjj of miles4 8 8 8 #j4i 8 8 8 #bbi1ahc 8 8 8 8 8 8 8 #j4h 8 8 8 #beg1hcj 8 8 8 8 8 8 8 #j4g 8 8 8 #bid1ffd 8 8 8 8 8 8 8 #j4f 8 8 8 #cdc1gej 8 8 8 8 8 8 8 #j4e 8 8 8 #dab1ecj 8 8 8 8 8 8 8 #j4d 8 8 8 #eae1ffj 8 8 8 8 8 8 8 #j4c 8 8 8 #fhg1ejj 8 8 8 8 8 8 8 #j4b 8 8 8 #a1jca1cbj 8 8 8 8 8 8 8 #j4a 8 8 8 #b1jfb1fej 8 8 8 8 8 8 8 #j4j 8 8 8 ,immeasurable4 ,the nearest star1 ,alpha ,centauri1 shows a parallax of less than one second 7#j4ge74 ,the farthest star1 the distance of which has been ascertained1 is #ahcj ,groombridge1 which shows a parallax of only #j4jde1 and is distant #d1ehc1jjj times earth's distance from the sun1 or #dbf trillions of miles4 ,the very thought of such unimaginable depths of space1 of suns beyond suns 8in endless range10 toned down by simple distance to mere quivering specks of light1 is well-nigh overwhelming4 ,,chapter ,,xxviii4 ,,the ,,milky ,,way4 ,the ,milky ,way forms a soft band of light round the whole heavens4 ,in the ,southern ,hemisphere1 as in the ,northern ,hemisphere1 it is to be seen4 ,in some parts the band narrows2 in some parts it widens4 ,here it divides into two branches2 there we find dark spaces in its midst4 ,one such space in the south is so black and almost starless as to have been named the ,coal-sack4 ,all along1 over the background of soft1 dim light1 lies a scattering of brighter stars shining on its surface4 ,much interest and curiosity have long been felt about this mysterious ,milky ,way4 ,that it consists of innumerable suns1 and that our sun is one among them1 has been believed for a considerable time4 ,but other questions arise4 ,how many stars does the ,milky ,way contain8 ,what is its shape8 ,how far does it reach8 ,no harm in asking the questions1 only we have to be satisfied in astronomy to ask many questions which can not yet receive answers4 ,no harm for man to learn that the utmost reach of his intellect must fall short in any attempt to sound the depths of ,god's universe1 even as the arm of a child would fall short in seeking to sound the depths of the ocean over the side of a little boat4 ,for the attempt has been made to sound the depths of our star-galaxy out of this little earth-boat4 ,the idea first occurred to the great ,herschel1 as we have already mentioned1 and a grand idea it was--only a hopeless one4 ,he turned his powerful telescope north1 south1 east1 west4 ,he counted the stars visible at one time in this1 in that1 in the other directions4 ,he found a marked difference in the numbers4 ,the portion of sky seen through his telescope was about one quarter the size of that covered by the moon4 ,sometimes he could merely perceive two or three bright points on a black background4 ,at other times the field of his telescope was crowded4 ,in the fuller portions of the ,milky ,way1 he had four or five hundred stars under view at once4 ,in one place he saw about one hundred and sixteen thousand stars pass before him in a single quarter of an hour4 ,herschel took it for granted that the stars of the ,milky ,way1 uncountable in numbers1 are1 as a rule1 much the same in size--so that brightest stars would1 as a rule1 be nearest1 and dimmest stars would1 as a rule1 be farthest off4 ,where he found stars clustering thickly1 beyond his power to penetrate1 he believed that the ,milky ,way reached very far in that direction4 ,where he found black space1 unlighted by stars or lighted by few stars1 he decided that he had found the borders of our galaxy in that direction4 ,following these rules which he had laid down1 he made a sort of rough sketch of what he supposed might be the shape of the ,milky ,way4 ,he thought it was somewhat flat1 extending to a good distance breadthways and a much greater distance lengthways1 and he placed our sun not far from the middle4 ,this imagined shape of the ,milky ,way is called 8,the ,cloven-disk ,theory40 ,to explain the appearance of the ,milky ,way in the sky1 ,herschel supposed it to be cloven or split through half of its length1 with a black space between the two split parts4 ,it seems that ,herschel did not hold strongly to this idea in later years1 and doubts are now felt whether the rules on which he formed it have sufficient foundation4 ,for how do we know that the stars of the ,milky ,way are1 as a rule1 much the same in size8 ,certainly the planets of the ,solar ,system are very far from being uniform1 and the few stars whose weight can with any certainty be measured1 seem to vary considerably4 ,there is a great difference also between the large and small suns in many of the double-stars6 ,again1 how do we know that the bright stars are1 as a rule1 the nearest1 and the dim stars the farthest off8 ,here1 also1 late discoveries make us doubtful4 ,look at ,sirius and #fa ,cygni--,sirius the most radiant star in the heavens1 and #fa ,cygni almost invisible to the naked eye4 ,according to this rule1 #fa ,cygni ought to lie at an enormous distance beyond ,sirius4 ,yet in actual fact1 ,sirius is the farthest away of the two4 ,the illustrious ,herschel believed that he had penetrated1 on one occasion1 into the star-cluster on the sword-hand in the constellation of ,perseus until he found himself among sidereal depths1 from which the light could not have reached him in less than four thousand years4 ,the distance of those stars had not1 and has not1 been mathematically measured4 ,herschel judged of it by their dimness1 by the strong power needed to make them visible1 and by the rules which he had adopted as most likely true4 ,again1 when ,herschel found black spaces in the heavens almost void of stars1 and believed that he had reached the outside borders of the ,milky ,way1 he may have been in the right1 or he may have been mistaken4 ,the limit might lie there1 or thousands more of small stars might extend in that very direction1 too far off for their little glimmer to be seen through the most powerful telescope4 ,illustration3 ,a ,,cluster ,,of ,,stars ,,in ,,perseus4 ,if this latter idea about the ,milky ,way being formed of a great many brilliant suns1 and of vast numbers of lesser suns also1 be true1 astronomers will1 in time1 be able to prove its truth4 ,for in that case1 many faint telescopic stars being much nearer to us than bright stars of the greater magnitudes1 it will be found possible to measure their distance4 ,the journey of our earth round the sun must cause a seeming change in their position between summer and winter4 ,the theory also that some of the nebul are other outlying ,milky ,ways1 or galaxies of stars1 separated by tremendous distances from our own1 is interesting1 and was long held as almost certain1 yet we have no distinct proof either one way or the other4 ,many of the nebul may be such gatherings of countless stars outside our own1 or every nebula visible may be actually part and parcel of our galaxy4 ,much attention has of late been paid to the arrangement of stars in the sky4 ,the more the matter is looked into1 the more plainly it is seen that stars are neither regular in size nor regular in distribution4 ,they are not merely scattered carelessly1 as it were1 here1 there1 and anywhere1 but certain laws and plans of arrangement seem to have been followed which astronomers are only now beginning dimly to perceive4 ,stars are not flung broadcast through the heavens1 each one alone and independent of the rest4 ,they are placed often1 as we have already seen1 in pairs1 in triplets1 in quartets1 in clusters4 ,also1 the great masses of them in the heavens seem to be more or less arranged in streams1 and sprays1 and spirals4 ,so remarkable are the numbers and forms of many of these streams that the idea has been suggested1 with regard to the ,milky ,way1 whether it also may not be a vast stream of stars1 like a mighty river1 collecting into itself hundreds of lesser streams4 ,the contemplation of the heavens affords no spectacle so grand and so eloquent as that of a cluster of stars4 ,most of them lie at such a distance that the most powerful telescopes still show them to us like star-dust4 8,their distance from us is such that they are beyond1 not only all our means of measurement10 says ,newcomb1 8but beyond all our powers of estimation4 ,minute as they appear1 there is nothing that we know of to prevent our supposing each of them to be the center of a group of planets as extensive as our own1 and each planet to be as full of inhabitants as this one4 ,we may thus think of them as little colonies on the outskirts of creation itself1 and as we see all the suns which give them light condensed into one little speck1 we might be led to think of the inhabitants of the various systems as holding intercourse with each other4 ,yet1 were we transported to one of these distant clusters1 and stationed on a planet circling one of the suns which compose it1 instead of finding the neighboring suns in close proximity1 we should see a firmament of stars around us1 such as we see from the earth4 ,probably it would be a brighter firmament1 in which so many stars would glow1 with more than the splendor of ,sirius1 as to make the night far brighter than ours2 but the inhabitants of the neighboring worlds would as completely elude telescopic vision as the inhabitants of ,mars do here4 ,consequently1 to the inhabitants of every planet in the cluster1 the question of the plurality of worlds might be as insolvable as it is to us40 ,these are clusters of stars of regular form in which attraction appears to mark its secular stamp4 ,our mind1 accustomed to order in the cosmos1 anxious for harmony in the organization of things1 is satisfied with these agglomerations of suns1 with these distant universes1 which realize in their entirety an aspect approaching the spherical form4 ,more extraordinary1 more marvelous still1 are the clusters of stars which appear organized in spirals4 ,in considering stars of the first six magnitudes only--stars visible to the naked eye--a somewhat larger number is found in the ,southern ,hemisphere than in the ,northern ,hemisphere4 ,in both hemispheres there are regions densely crowded with stars1 and regions by comparison almost empty4 ,it has been long questioned whether the number of bright stars is or is not greater in the ,milky ,way than in other parts of the sky4 ,careful calculations have at length been made4 ,it appears that the whole of the ,milky ,way--that zone of soft light passing round the earth--covers1 if we leave out the ,coal-sack and other such gaps1 between one-tenth and one-eleventh of the whole heavens4 ,the entire number of naked-eye stars1 or stars of the first six magnitudes1 does not exceed six thousand2 and of these1 eleven hundred and fifteen lie scattered along the bed of the ,milky ,way stream4 ,if the brighter stars were scattered over all the sky as thickly as throughout the ,milky ,way1 their number would amount to twelve thousand instead of only six thousand4 ,this shows us that the higher-magnitude stars really are collected along the ,milky ,way in greater numbers than elsewhere1 and is an argument used by those who believe the ,milky ,way to be a mighty stream of streams of stars4 ,in the dark spaces of the ,milky ,way1 on the contrary1 bright stars are so few that if they were scattered in the same manner over all the sky1 their present number of six thousand would come down to twelve hundred and forty4 ,this would be a serious loss4 ,we know in the sky #a1jcd clusters of stars and more than #aa1jjj nebul4 ,the former are composed of associated stars2 the latter may be divided into two classes3 ,first1 nebul which the ever-increasing progress of optics will one day resolve into stars1 or which in any case are composed of stars1 although their distances may be too great to enable us to prove it2 second1 nebul properly so called1 of which spectrum analysis demonstrates their gaseous constitution4 ,here is an instructive fact4 ,the clusters of stars present the same general distribution as the telescopic stars--they are more numerous in the plane of the ,milky ,way1 while it is the contrary which is presented by the nebul properly so called2 they are rare1 thinly spread in the ,milky ,way1 and thickly scattered to the north as well as to the south of this zone up to its poles4 ,the constitution of the ,milky ,way--not nebulous1 but stellar--is a very significant fact4 ,the nebul properly so called are distributed1 in a sense1 contrary to the stars1 being more numerous towards the poles of the ,milky ,way and in regions poor in stars1 as if they had absorbed the matter of which the stars are formed4 ,,chapter ,,xxix4 ,a ,,whirling ,,universe4 ,no rest1 no quiet1 no repose1 in that great universe1 which to our dim eyesight looks so fixed and still1 but one perpetual rush of moving suns and worlds4 ,for every star has its own particular motion1 every sun is pressing forward in its own appointed path4 ,and among the myriads of stars--bright1 blazing furnaces of white or golden1 red1 blue1 or green flame--sweeping with steady rush through space1 our sun also hastens onwards4 ,the rate of his speed is not very certain1 but it is generally believed to be about one hundred and fifty million miles each year4 ,possibly he moves in reality much faster4 ,when ,i speak of the sun's movement1 it must of course be understood that the earth and planets all travel with him1 much as a great steamer on the sea might drag in his wake a number of little boats4 ,from one of the little boats you could judge of the steamer's motion quite as well as if you were on the steamer itself4 ,astronomers can only judge of the sun's motion by watching the seeming backward drift of stars to the right and left of him2 and the watching can be as well accomplished from earth as from the sun himself4 ,after all1 this mode of judging is1 and must be1 very uncertain4 ,among the millions of stars visible1 we only know the real distances of about twenty-five2 and every star has its own real motion1 which has to be separated from the apparent change of position caused by the sun's advance4 ,it seems now pretty clear that the sun's course is directed towards a certain point in the constellation ,hercules4 ,if the sun's path were straight1 he might be expected by and by1 after long ages1 to enter that constellation4 ,but if orbits of suns1 like orbits of planets1 are ellipses1 he will curve away sideways long before he reaches ,hercules4 ,illustration3 ,,hercules ,one ,german astronomer thought he had found the center of the sun's orbit4 ,he believed the sun and the stars of the ,milky ,way to be traveling round the chief star in the ,pleiades1 ,alcyone4 ,this is not impossible2 but it is now felt that much stronger proof will be required before the idea can be accepted4 ,in the last chapter mention was made of star-streams as a late discovery4 ,though a discovery still in its infancy1 it is one of no small importance4 ,briefly stated1 the old theory as to the plan of the ,milky ,way was as follows3 ,our sun was a single star among millions of stars forming the galaxy1 some comparatively near1 some lying at distances past human powers of calculation1 and all formed upon much the same model as to size and brightness4 ,where the band of milky light showed1 stars were believed to extend in countless thousands to measureless distances4 ,where dark spaces showed1 it was believed that we looked beyond the limits of our universe into black space4 ,stars scattered in other parts of the sky were supposed generally to be outlying members of the same great ,milky ,way4 ,many of the nebul and star-clusters were believed to be vast and distant gatherings of stars1 like the ,milky ,way itself1 but separated by unutterably wide reaches of space4 ,some of these views may yet be found to contain truth1 though at the present moment a different theory is afloat4 ,it is still thought probable that our sun is one among many millions of suns1 forming a vast system or collection of stars1 called by some a universe4 ,it is also thought possible that other such mighty collections of stars may exist outside and separate from our own at immense distances4 ,it is thought not impossible or improbable that some among the nebul may be such far-off galaxies of stars2 though1 on the other hand1 it is felt that every star-cluster and nebula within reach of man's sight may form a part of our own 8universe40 ,according to this view of the question1 the ,milky ,way1 instead of being an enormous universe of countless suns reaching to incalculable distances1 may rather be a vast and mighty star-stream1 consisting of hundreds of brilliant leading suns1 intermixed with thousands or even millions of lesser shining orbs4 ,if this be the true view1 the lesser suns would often be nearer than the greater suns1 although more dim2 and the ,milky ,way would not be itself a universe1 though a very wonderful and beautiful portion of our universe4 ,which of these two different theories or opinions contains the most truth remains to be found out4 ,but respecting the arrangement of stars into streams1 interesting facts have lately been discovered4 ,we certainly see in the ,solar ,system a tendency of heavenly bodies to travel in the same lines and in companies4 ,not to speak of ,jupiter and his moons1 or ,saturn and his moons1 we see it more remarkably in the hundreds of asteroids pursuing one path1 the millions of meteorites whirling in herds4 ,would there be anything startling in the same tendency appearing on a mightier scale8 ,should we be greatly astonished to find streams of stars1 as well as streams of planets8 ,for such1 indeed1 appears to be the case4 ,separated by abysses of space1 brother suns are plainly to be seen journeying side by side through the heavens1 towards the same goal4 ,the question of star-drift is too complex and difficult to be gone into closely in a book of this kind4 ,one example1 however1 may be given4 ,almost everybody knows by sight the constellation of the ,great ,bear--the seven principal stars of which are called also ,charles's ,wain1 a corruption of the old ,gothic ,karl ,wagen1 the churl's or peasant's wagon4 ,it is also called the ,great ,dipper4 ,four bright stars form a rough sort of oblong1 and from one of the corners three more bright stars stretch away in a curve1 representing the ,bear's tail4 ,many smaller stars are intermixed4 ,illustration3 ,,the ,,great ,,bear4 ,these seven bright stars have always been bound together in men's minds1 as if they belonged to one another4 ,but who1 through the centuries past1 since aught was known of the real distances of the stars from ourselves and from one another1 ever supposed that any among the seven were really connected together8 ,one of these seven stars1 the middle one in the tail1 has a tiny companion-star1 close to it1 visible to the naked eye4 ,for a good while it was uncertain whether the two were a 8real double10 or only a seeming double4 ,in time it became clear that the two did actually belong to one another4 ,mizar is the name of the chief star1 and ,alcor of the companion4 ,alcor is believed to be about three thousand times as far away from ,mizar1 as our earth from the sun4 ,now1 if this be the width of space between those two bright points1 lying seemingly so close together as almost to look to the naked eye like one1 what must be the distance between the seven leading stars of the ,great ,bear1 separated by broad sky-spaces8 ,who could imagine that one of these suns had aught to do with the rest8 ,yet among other amazing discoveries of late years it has been found by means of the new instrument1 the spectroscope1 that five out of these seven suns are traveling the same journey1 with the same speed4 ,two of the seven appear to be moving in another direction1 but three of the body-stars and two of the tail-stars are hastening in the direction away from us1 all in the same line of march1 all rushing through space at the rate of twenty miles each second4 ,some smaller stars close to them are also moving in the same path4 ,is not this wonderful8 ,we see here a vast system of suns1 all moving towards one goal1 and each probably bearing with him his own family of worlds4 ,many such streams have been noticed1 and many more will doubtless be found4 ,for aught we know1 our own sun may be one among such a company of brother-suns1 traveling in company4 ,it is difficult to give any clear idea of the immensity of the universe--even of that portion of the universe which lies within reach of our most powerful telescopes4 ,how far beyond such limits it may reach1 we lose ourselves in imagining4 ,earlier in the book we have supposed possible models of the ,solar ,system1 bringing down the sun and worlds to a small size1 yet keeping due proportions4 ,what if we were to attempt to make a reduced model of the universe2 that is of just so much of it as comes within our ken8 ,suppose a man were to set himself to form such a model1 including every star which has ever been seen4 ,let him have one tiny ball for the sun1 and another tiny ball for ,alpha ,centauri2 and let him1 as a beginning1 set the two one yard apart4 ,that single yard represents ninety-three millions of miles1 two hundred and seventy-five thousand times repeated4 ,then let him arrange countless multitudes of other tiny balls1 at due distances--some five times1 ten times1 twenty times1 fifty times1 as far away from the sun as ,alpha ,centauri4 ,it is said that the known universe1 made upon a model of these proportions1 would be many miles in length and breadth4 ,but the model would appear fixed as marble4 ,the sizes and distances of the stars being so enormously reduced1 their rates of motion would be lessened in proportion4 ,long intervals of time would need to pass before the faintest motion in one of the millions of tiny balls could become visible to a human eye4 ,,chapter ,,xxx4 ,,reading ,,the ,,light4 ,illustration3 ,,the ,,prism ,,and ,,spectrum4 ,several times1 in the course of this book1 mention has been made of a wonderful new instrument called the spectroscope4 ,we now proceed to give a brief account of the origin and achievements of this newest of scientific appliances4 ,the first step towards its formation was made by ,sir ,isaac ,newton1 when he discovered the power of the prism to decompose light4 ,this consists in the fact that a ray of light1 after passing through a transparent prism1 becomes expanded into an elongated spectrum1 no longer white1 but presenting an invariable succession of colors from red to violet4 ,these are called the seven primary colors2 namely1 red1 orange1 yellow1 green1 blue1 indigo1 and violet4 ,the rainbow is a familiar illustration of this spectrum with its various colors2 and the raindrops are the prisms which reflect and decompose the light4 ,illustration3 ,,the ,,spectroscope4 ,optical science was long satisfied with this glance into the interior constitution of light1 occupying itself with the phenomena of the prismatic colors1 and theorizing on the nature of white light4 ,in #ahjb1 ,dr4 ,w4 ,h4 ,wollaston1 in closely examining a spectrum1 found it to be crossed by at least four fine dark lines4 ,it is only when an extremely narrow slit is employed in admitting the sunlight that they become visible4 ,dr4 ,wollaston1 supposing them to be merely 8natural boundaries0 of the different color-bands1 inquired no further2 and there for a while the matter rested4 ,not many years later1 in #ahae1 the matter was taken up by a ,german optician and scientist of ,munich1 ,joseph von ,fraunhofer4 ,applying more delicate means of observation1 he was surprised to find very numerous dark lines crossing the spectrum4 ,with patience he went into the question1 using the telescope as well as a very narrow slit1 and soon he discovered that the dark lines were to be numbered1 not by units or by tens1 but by hundreds--or1 as we now know1 by thousands4 ,some were in the red1 some were in the violet1 some were in the intermediate bands2 but each one had1 and has1 its own invariable position on the solar spectrum4 ,for1 be it understood1 these dark lines are constant1 not variable4 ,where a line is seen1 there it remains4 ,whenever a ray of sunlight is properly examined1 with slit and with prism1 that line will be found always occupying precisely the same spot in the spectrum4 ,some of the chief and more distinct lines were named by ,fraunhofer after certain letters of the alphabet1 and by those letter-names they are still known4 ,he began with ,a in the red and went on to ,h in the violet4 ,fraunhofer made a great many experiments connected with these mysterious lines1 anxious to discover1 if possible1 their meaning4 ,for although he now saw the lines1 which had scarcely so much as been seen before1 he could not understand them--he could not read what they said4 ,they spoke to him1 indeed1 about the sun2 but they spoke in a foreign language1 the key to which he did not possess4 ,he tried making use of prisms of different materials1 thinking that perhaps the lines might be due to something in the nature of the prism employed4 ,but let the prism be what it might1 he found the lines still there4 ,then he examined the light which shines from bright clouds1 instead of capturing a ray direct from the sun4 ,and he found the lines still there4 ,for cloudlight is merely reflected sunlight4 ,then he examined the light of the moon1 to see if perchance the spectrum might be clear of breaks4 ,and he found the lines still there4 ,for moonlight is only reflected sunlight4 ,next he set himself to examine the light which travels to us from some of the planets1 imagining that a different result might follow4 ,and he found the lines still there4 ,for planet-light again is no more than reflected sunlight4 ,illustration3 ,,spectra1 ,,showing ,,the ,,dark ,,lines4 ,lastly1 he turned his attention to some of the brighter stars1 examining1 one by one1 the ray which came from each4 ,and1 behold6 he found the lines not there4 ,for starlight is not reflected sunlight4 ,that is to say1 the identical lines which distinguish sunlight were not there4 ,each star had a spectrum as the sun has a spectrum1 and each star-spectrum was crossed by faint dark lines1 more or less in number4 ,but the spectra of the stars differed from the spectrum of the sun4 ,each particular star had its own particular spectrum of light1 different from that of the sun1 and different from that of every other star4 ,for now1 ,fraunhofer was examining1 not sunlight1 but starlight2 not the light of our sun1 either direct from himself or reflected from some other body1 such as planet or moon or cloud1 but the light of other suns very far distant1 each one varying to some extent from the rest in its make4 ,the fact of the stars showing numerous sets of black lines1 all unlike those of our sun1 showed conclusively that those lines could not possibly be due to anything in our earthly atmosphere4 ,sunlight and starlight travel equally through the air1 and are equally affected by it4 ,if our atmosphere were the cause of the black lines in sunlight1 it would cause the same lines in starlight4 ,but the sun and each individual star has its own individual lines1 quite irrespective of changeful states of the air4 ,so1 also1 the light from any metal sufficiently heated will give a spectrum1 just as sunlight gives a spectrum1 under the needful conditions4 ,that is to say1 there must be slit and prism1 or slit and diffraction-grating1 for the light to pass through4 ,but the kind of spectrum is by no means always the same4 ,putting aside for a few minutes the thought of sunlight and starlight1 let us look at the kind of rays or beams which are given forth by heated earthly substances4 ,any very much heated substance sends forth its light in rays or beams1 and any such rays or beams may be passed through a prism1 and broken up or 8analyzed10 just as easily as sunlight may be 8analyzed40 ,suppose that we have a solid substance first--a piece of iron or of steel wire4 ,if it is heated so far as to give out1 not only heat1 but also light1 and if that light is made to travel through the slit and prism of a spectroscope1 the ray will then be broken up into its sub-rays4 ,they1 like the sub-rays of a sunbeam1 will form a continuous row of soft color-bands1 one melting into another4 ,this is the characteristic spectrum of the light which is given forth by a burning or glowing solid4 ,next1 suppose we take a liquid--some molten iron or some molten glass1 for instance4 ,if you have ever been to a great plate-glass manufactory1 like that at ,st4 ,helens1 not far from ,manchester1 you will have seen streams of liquid glass pouring about1 carried to and fro in huge caldrons1 bright with a living light of fire from its intensity of heat4 ,if a ray of that light had been passed through slit and prism1 what do you think would have been the result8 ,a continuous spectrum once more1 the same as with the glowing iron or steel4 ,the light-ray from a heated and radiant liquid1 when broken up by a prism1 lies in soft bands of color1 side by side4 ,both of them a good deal like the solar spectrum1 you will say4 ,only here are no mysterious dark lines crossing the bright bands of color4 ,but how about gases8 ,suppose we have a substance in the state of gas or vapor1 as almost every known substance might be under the requisite conditions1 and suppose that substance to be heated to a glowing brilliance4 ,then let its light be passed through the slit and prism of a spectroscope4 ,what result shall we find this time8 ,entirely different from anything seen before4 ,instead of soft1 continuous bands of color1 there are bright lines1 well separated and sharply defined4 ,how many bright lines8 ,ah1 that depends upon which particular gas is having its ray analyzed4 ,try sodium first--one of the commonest of earthly substances4 ,enormous quantities of it are distributed broadcast in earth and air and water4 ,more than two-thirds of the surface of our globe lies under an enfolding vesture of water saturated with salt1 which is a compound of sodium4 ,that is to say1 sodium enters largely into the make of salt4 ,every breeze which sweeps over the ocean carries salt inland1 to float through the atmosphere4 ,sir ,h4 ,e4 ,roscoe writes3 8,there is not a speck of dust1 or a mote seen dancing in the sunbeam1 which does not contain chloride of sodium0--otherwise salt4 ,the very air which surrounds us is full of compounds of sodium1 and we can not breathe without taking some of it into our bodies4 ,sodium is an 8elementary substance40 ,by which ,i mean that it is one of a number of substances called by us 8simple10 because chemists have never yet succeeded in breaking up those substances1 by any means at their command1 into other and different materials4 ,iron is1 so far as we know1 a simple substance4 ,it is found as iron in the earth4 ,no chemist has ever been able to make iron by combining other materials together4 ,no chemist has ever managed to separate iron into other materials unlike itself4 ,iron it is1 and iron it remains1 whether as a solid1 as a liquid1 or as a gas4 ,gold is another simple substance1 and so is silver4 ,sodium is another4 ,all these we know best in the solid form4 ,mercury1 another simple substance1 we know best as a liquid4 ,water is not a simple substance2 for it can be separated into two different gases4 ,glass is not a simple substance2 for it is manufactured out of other substances combined together4 ,we can speak quite positively as to such substances as are not simple2 but with regard to so-called 8elements10 we may only venture to assert that1 thus far1 nobody has succeeded in breaking them up4 ,therefore1 at least for the present1 they are to us 8elementary40 ,all the simple substances1 and very many of the combinations of them1 though often known to us only in the solid form1 may1 under particular conditions1 be rendered liquid1 and even gaseous4 ,every metal may be either in the solid form1 or the liquid form1 or the vapor form4 ,iron1 as we commonly see it1 is solid--in other words1 it is frozen1 like ice4 ,just as increase of warmth will turn ice into water1 so a certain amount of heat will make solid iron become liquid iron4 ,and just as yet greater warmth will turn water into steam1 so a very much increased amount of heat will turn liquid iron into vapor of iron4 ,a little heat will do for ice what very great heat will do for iron4 ,whether iron and other metals exist in the sun1 as on earth1 in a hard and solid form1 it is impossible to say4 ,it is only in the form of gas that man can become aware of their presence at that distance4 ,the intense1 glowing1 furnace-heat of the sun causes many metals to be present in large quantities in the sun's atmosphere in the form of vapor4 ,not only have we learned about some of the metals in the sun1 but this strange spectrum analysis has taught us about some of the metals and gases in the stars as well4 ,it is found that in ,sirius1 sodium and magnesium1 iron and hydrogen1 exist4 ,in ,vega and ,pollux there are sodium1 magnesium1 and iron4 ,in ,aldebaran1 these substances and many others1 including mercury1 seem to abound4 ,these are merely a few examples among many stars1 each being in some degree different from the rest4 ,but how can we know all this8 ,how could the wildest guessing reveal to us the fact of iron in the sun1 not to speak of the stars8 ,we know it by means of the spectrum analysis--or1 as we may say1 by means of the spectroscope4 ,this instrument may be looked upon as the twin-sister to the telescope4 ,the telescope gathers together the scattered rays of light into a small spot or focus4 ,the spectroscope tears up these rays of light into ribbons1 sorts them1 sifts them1 and enables us to read in them hidden meanings4 ,when a ray of light reaches us from the sun1 that ray is white2 but in the white ray there are bright colors concealed4 ,newton was the first to discover that a ray of white light is really a bundle of colored rays1 so mixed up together as to appear white4 ,if a ray of sunlight is allowed to pass through a small round hole in a wall1 it will fall upon the opposite wall in a small round patch of white light4 ,but if a prism--a piece of glass cut in a particular shape--is put in the path of the ray1 it has power to do two curious things4 ,first1 it bends the ray out of a straight course1 causing the light to fall upon a different part of the wall4 ,secondly1 it breaks up or divides the ray of white light into the several rays of colored light of which the white ray is really composed4 ,this breaking up1 or dividing1 is called 8analyzing40 ,if in place of a round hole the ray of light is made to pass through a very narrow slit1 it is proved that the bright bands of color do not overlap4 ,instead of this1 dark lines1 or gaps1 show here and there4 ,now1 these lines or gaps are always to be seen in the spectrum or image of bright colors formed by a broken-up ray of sunlight4 ,there is always a certain number of dark lines in each colored band--some near together1 some far apart2 here one or two1 there a great many4 ,where a simple ray of sunlight is concerned1 the exact arrangement of the lines never changes4 ,when the stars were examined--when the rays of light coming from various stars were split up and analyzed--it was found that they too1 like the sun1 gave a spectrum of bright colors with dark lines4 ,but the lines were different in number and different in arrangement from the sun's lines4 ,each star has his own particular number and his own particular arrangement1 and that arrangement and number do not change4 ,if a white-hot metal is burnt1 and the light of it as it burns is allowed to pass through a prism1 a row of bright colors appears as in the sun's spectrum1 only there are no dark lines4 ,if a gas is burnt1 and the light is allowed to pass through a prism1 no bright color-bands appear1 and no dark lines either2 but instead of this1 there are bright lines4 ,each gas or vapor has its own number of lines and its own arrangement4 ,sodium shows two bright lines1 side by side4 ,iron shows sixty bright lines1 arranged in a particular way4 ,now you see how a row of bright colors without bands of color may appear4 ,but what about color-bands and dark lines together8 ,that discovery came latest4 ,it was found that if a white-hot metal were burned1 and if its light were allowed before touching the prism to shine through the flame of a burning gas1 then there were dark lines showing in the colored bands4 ,these dark lines changed in position and number and arrangement with each different kind of gas1 just as the bright lines changed if the gases were burned alone4 ,if the light of the burning metal passed through a flame colored with gas of sodium1 two dark lines showed on one part of the spectrum2 but if it passed through a flame colored with vapor of iron1 sixty dark lines showed on another part of the spectrum4 ,so now1 by means of this spectrum analysis1 we know with all but certainty that the sun and stars are solid1 burning bodies1 sending their light through burning1 gas-laden atmospheres4 ,by examining the little black lines which appear in the spectrum of one or another1 it is possible to say the names of many metals existing as gas in those far-off heavenly bodies4 ,is not this a wonderful way of reading light8 ,the split-up rays tell us much more than the kinds of metals in different stars4 ,when a nebula is examined1 and is found to give no spectrum of bright bands and dark lines1 but only a certain number of bright lines1 we know it to be formed of gas1 unlike stars and other nebul4 ,also1 it is by means of the spectroscope that so much has lately been discovered about the motions and speed of the stars coming towards or going from us4 ,,chapter ,,xxxi4 ,,stellar ,,photography4 ,photography is not only a useful handmaid to astronomy as a whole1 but also it is so1 peculiarly1 to that division of astronomy with which we are now chiefly concerned--to spectroscopy4 ,a few pages may therefore with advantage be given to the subject of celestial photography4 ,photography is1 indeed1 the greatest possible help to the astronomer4 ,it pictures for him those stars which his eyes can see but dimly1 or even can not see at all2 it paints for him those light-rays of which he would obtain but a passing glance1 and which he could not accurately remember in all their details2 it maps out for him the wide heavens1 which he1 unaided1 could never do with anything like equal completeness by eye and hand alone4 ,only recently a vast photographic map of the whole sky was undertaken4 ,about eighteen different observatories1 in divers parts of the world1 divided the task among them1 stars down to the sixteenth magnitude being most carefully registered in a complete series of something like fifteen hundred separate photographs4 ,the whole result1 when finally completed1 will be a grand achievement of the present century4 ,each individual star1 in the entire heavens all around our earth1 from the first to the sixteenth magnitudes1 will have its exact position in the sky accurately known1 and the smallest change in the position of anyone of those stars may then be detected4 ,even in the delicate and abstruse operation earlier described1 the measurement of star-distances through annual parallax1 photography again steps in4 ,dr4 ,pritchard1 ,savilian professor of ,astronomy at ,oxford1 pressed photography into the service of this task also4 ,measurements for parallax were made under his direction upon photographic plates--a work of no small interest4 ,here1 as elsewhere1 peculiar advantages belong to the photographic method when it can be followed4 ,its records are lasting1 the limited number of hours which are fully suitable for direct astronomical work may be employed in obtaining those records1 and in broad daylight the examination of them can be carried on4 ,one very curious use is made of star-photographs1 more especially of the photographs of unseen stars--that is1 of stars too distant or too dim to be detected by the eye4 ,these photographs1 when taken1 may be afterwards looked into further with a microscope4 ,so1 first1 the far-off1 invisible suns of the universe are photographed on a prepared plate1 with the help of a powerful telescope1 this being needful to secure sufficient starlight2 and then the tiny picture of those suns is examined more closely with the help of a powerful microscope4 ,spectroscopy has much to say to us4 ,it tells us about the positions of the different stars4 ,it tells us about the structure of the stars4 ,it tells us about the various classes to which the various stars belong4 ,and also it tells us about the motions of the stars--not mere apparent motions1 caused by movements of our own earth1 but true onward journeyings of the stars themselves through the depths of space4 ,for by means of photography we do not obtain simple pictures of the stars themselves only1 but pictures also of the spectra of the stars4 ,an instrument is made uniting the spectroscope with the photographic apparatus1 and this is called a spectrograph4 ,by its means the disintegrated or broken-up star-ray is photographed in its broken-up condition1 so that an exact picture is obtained of the bands and lines characteristic of any particular star4 ,no easy matter1 as may be imagined1 are these spectroscopic observations and these spectroscopic photographings of the stars4 ,to bring the image of a star exactly opposite a slender opening or slit1 perhaps only about the three-hundredth part of an inch in width1 and to keep it there1 is a task which might well be looked upon as practically impossible4 ,no sooner is a star found in the field of a telescope than it vanishes again4 ,as the astronomer gazes1 the ground beneath him is ever whirling onward1 leaving the star behind2 and although clockwork apparatus in all observatories of any importance is made to counteract this motion of the earth1 and to keep the heavenly object1 whether star or moon1 or comet1 within view by following its apparent motion1 yet1 as can easily be imagined1 to follow thus the seeming motion of a dim star through an opening so minute1 demands exceeding care and delicacy of adjustment4 ,it is not indeed1 for purposes of analysis1 always needful to pass the light of a star through a narrow slit4 ,in the case of a nearer body1 such as the sun or moon or one of the planets1 light flows from all parts of the body1 one ray crossing another2 and for the examination of such light1 a slit is imperatively needed1 all side-rays having to be cut off4 ,but the whole of the brightest star in the sky is only one point of light to us1 and a slitless telescope may be used with no confused results4 ,where1 however1 direct comparison is required1 the star-lines being made to appear1 side by side or above and below1 with the solar spectrum1 or with the lines of earthly metals1 then the slit becomes unavoidable4 ,by such comparison of the two1 side by side--the light from an intensely-heated earthly substance and the light from a star1 the rays of both being broken up in the spectroscope--the oneness or difference of lines in the rays can be easily made out4 ,one main difficulty in such observations arises from the diminution of starlight1 caused by its passage through a prism4 ,if a rope of a dozen strands is untwisted1 each of those strands is far weaker than the whole rope was2 and each strand of color in the twisted rope of light is of necessity much more feeble1 seen by itself1 than the whole white ray seen in one4 ,another difficulty in our country generally is the climate1 which gives so few days or hours in the year for effective work4 ,yet the full amount accomplished by seizing upon every possible opportunity is1 in the aggregate1 astonishing4 ,a third and very pressing difficulty attendant upon examination of star-spectra is caused by the incessant motion of our air1 through which1 as through a veil1 all observations have to be made4 ,the astronomer can never get away from the atmosphere2 and unless the air be very still--that is to say1 as still as it ever can remain--the spectrum-lines are so uncertainly seen as to make satisfactory results impossible4 ,dr4 ,huggins has sometimes passed hours in the examination of a single line1 unable to determine whether or no it precisely coincided with the comparison-line of some earthly substance4 ,in this matter1 no leaping at conclusions is admissible4 ,the photography of stars would be easy enough if one could just expose a plate to the shining of the star1 and there leave it to be impressed--there leave the star-ray to sketch slowly its own image4 ,but this is hardly possible4 ,the unceasing motion of the earth1 causing the star perpetually to pass away from the telescopic field1 and the exceeding narrowness of the slit opposite to which the star has to be kept in a stationary position1 make the most accurate adjustment needful4 ,clockwork alone can not be trusted4 ,if it could1 the star and the photographic apparatus might be comfortably 8fixed10 and left to do their own work4 ,instead of which1 while a photograph is proceeding1 it is desirable that an observer should sit gazing patiently at the telescope-tube1 where the image of the star is seen1 ready at any moment to correct by a touch the slightest irregularity in the clockwork motion of the telescope1 and so to prevent a blurred and spoilt reproduction of the star1 or of its spectrum4 ,one hour1 two hours1 three hours1 at a stretch1 this unceasing watchfulness may have to be kept up1 and no small amount of enthusiasm in the cause of science is requisite for so monotonous and wearying a vigil4 ,as noted earlier1 it has been found possible1 if the photograph of a star or nebula is not completed in one night1 to renew the work and carry it on the next night1 or even for many nights in succession4 ,this is especially practicable in spectroscopic photography4 ,from four to five hours1 sometimes from eight to ten hours1 may be needful before the clear image of the star or of its spectrum appears--a dim little star probably to us1 yet perhaps in reality a splendid sun1 shedding warmth and light and life upon any number of such worlds as ours4 ,eight or ten hours of photography at one stretch with a star are impossible2 for the stars1 ever seemingly on the move1 do not remain long enough in a good position4 ,for three to six hours1 a telescope may be made1 by means of its clockwork machinery1 to keep a star steadily in sight1 and all that while the photograph is progressing4 ,if further exposure is needed1 the process has to be resumed the next night4 ,the more one considers the matter1 the more plainly one perceives how enormously our powers of sky-observation are increased by photography4 ,it is not only that one photographer1 with his apparatus1 may accomplish in a single night the work of many astronomers who have to depend upon the power of the eye alone4 ,it is not only that1 with the help of photography1 as much can now be done in a lifetime as formerly must have occupied many generations4 ,it is not only that the photograph1 once taken1 remains a permanent possession1 instead of a record1 more or less imperfect1 in which otherwise the astronomer would have to trust4 ,it is not even only that in the photograph details come out which could not be detected by the eye1 and that stars are actually brought to our knowledge which no man has ever seen1 which perhaps no man ever will see from this earth with the assistance of the most powerful telescope4 ,for the weak shining1 which can by no possibility make itself felt by the retina of a man's eye1 can slowly impress its picture on the photographic plate4 ,hundreds of stars1 thousands of stars1 utterly invisible to man1 have had their photographs taken as truly as you have had your photograph taken1 and by the same process1 only it has been a longer business4 ,but in addition to all this1 we see reproduced upon the plate those ultra-violet and infra-red portions of the spectrum of light which but for the handmaid1 photography1 would still be to us as things which have no existence4 ,and by means of photography we can observe and study in those same unseen portions of the spectra1 when looking into a ray from sun or star1 the innumerable dark lines1 every one of which has its own tale to tell4 ,to these tales we must have remained blind and deaf1 but for photographic aid to our limited powers4 ,look at some dim star in the sky1 and try how long you can gaze without blinking4 ,you will very soon find that you have done your best1 and that to gaze longer only means a sense of fatigue in your eyes1 a growing dimness in the star4 ,how different with the photographic plate6 ,there1 no exertion is wasted1 no weariness is felt4 ,faint though the light may be1 which travels earthward and falls upon the plate1 it is all collected1 all used4 ,it is easy to photograph the sun1 and this has been done4 ,when we come to the moon the operation is more difficult on account of the feeble intensity of its light1 and the difference of tint of the various parts of its surface4 ,skill and perseverance have1 however1 surmounted the greatest difficulties1 and now we have photographs of the moon enlarged to more than a yard in diameter1 which show the smallest details with a truly admirable clearness4 ,in the first second of time1 your eye receives as much light from the star as does the photographic plate in the same time4 ,but during the course of one hour1 the plate receives and stores up about thirty-six hundred times as much light as it or you received in the first instant4 ,there is the secret of the matter4 ,the photographic plate does not only receive1 it can also keep and treasure up the light1 and that our eyes are not able to do4 ,if you magnify the amount received in one hour by five or ten1 and remember that it is all retained1 then you will begin to understand how feeble stars1 unseen by man1 should become known to us through photography4 ,,chapter ,,xxxii4 ,,the ,,dawn ,,of ,,astronomy4 ,the beginnings of astronomy lie in the distance of earliest historical ages4 ,it is no easy matter to say when first1 in all probability1 this science grew into existence4 ,astronomy was alive before the ,british nation was heard of2 before ,saxons or ,franks had sprung into being2 before the ,roman ,empire extended its iron rule2 before the ,grecian ,empire began to flourish2 before the ,persian ,empire gained power2 before the yet earlier ,assyrian ,empire held sway4 ,among the ancient ,chaldeans were devoted star-gazers--much more devoted than the ordinary run of educated ,anglo-,saxons in this present century4 ,they earnestly sought1 in the dim light of those ages1 to decipher the meaning of heaven's countless lamps4 ,we have better instruments1 and more practiced modes of reasoning2 also1 we have the collected piles of knowledge built up by our forefathers through tens of centuries4 ,yet our search is in essence the same as was theirs1 to know the truth about the stars3 not merely to start some attractive theory1 and then to prove that our theory must be right1 because we have been so clever as to start it2 but to discover that which is in those regions of space4 ,no lower aim than this is worthy to be called scientific4 ,mistakes1 of course1 are made2 how should it be otherwise8 ,a man finding his way at night1 for the first time1 through a wild and unknown country1 will almost certainly take some wrong turns before he discovers the right road4 ,in astronomy1 as in all other natural sciences1 blunders are a necessity if advance is to be made4 ,we have to grope our way to knowledge through observation and conjecture2 in simpler terms1 through gazing and guessing4 ,observation of facts leads to conjecture as to the possible causes for those facts2 and each conjecture is proved by later observation to be either right or wrong4 ,if proved to be right1 it takes its place among accepted truths2 if proved to be wrong1 it is flung aside4 ,some pet delusions die hard1 because of people's love for them4 ,astronomy1 as an infant science1 mixed up with astrology1 existed in the days when the ,pyramids were juvenile1 and when the ,assyrian sculptures were modern4 ,how much farther back who shall say8 ,by astrology1 those who studied the heavens endeavored to determine the fate of men and of nations1 to predict events1 and to interpret results4 ,they paid particular attention to the aspect of the planets1 and the general appearance of the firmament4 ,these observations were at first simple remarks made by the shepherds of the ,himalayas after sunset and before sunrise3 ,the phases of the moon1 and diurnal retrograde motion of that body with reference to the sun and stars2 the apparent motion of the starry sky accomplished silently above our heads2 the movements of the beautiful planets through the constellations2 the shooting star1 which seems to fall from the heavens2 eclipses of the sun and moon1 mysterious subjects of terror2 curious comets1 which appear with disheveled hair in the heights of heaven1--such were the first subjects of these old observations made during thousands of years4 ,the ancient ,chaldean star-gazers had rivals among the early ,egyptians2 and the ,chinese profess to have kept actual record of eclipses during between three and four thousand years4 ,the earlier records are not trustworthy2 but of thirty-six eclipses reckoned by the ,chinese sage1 ,confucius1 no less than thirty-one have been proved true by modern astronomers4 ,we can not name with certainty those people whose shepherds first gazed with intelligent eyes upon the midnight sky1 and noted the steady sweep of stars across the firmament--intelligent eyes1 that is to say1 so far as man then knew how to use his eyes intelligently2 so far as man had begun to note anything in nature1 to watch1 to compare1 and to conjecture causes4 ,in those times1 and indeed for long afterwards1 men thought much more about the 8influences0 of stars upon their own lives1 and about supposed prophecies of the future to be read in the sky1 than about the actual physical condition of the stars themselves1 or the causes and meanings of the various phenomena observed in the heavens4 ,the desire to know1 for the pure delight of knowing1 had perhaps hardly begun to dawn upon the mind of man4 ,what people did want to know was what might be going to happen to themselves2 whether they would be happy or unhappy2 and the stars were chiefly of interest as appearing to tell beforehand of troubles or joys to come4 ,the wisest of men in those times knew less of the outspread heavens than many a child now knows in our public schools4 ,earth and sky were one vast bewildering puzzle4 ,they had to discover everything for themselves--how the sun rose each morning and set each evening2 how the seasons changed in steady sequence through the year2 how the moon and stars journeyed in the night2 how the ocean-tides went and came2 how numberless every-day phenomena took place4 ,in olden days the daily rising and setting of the sun was a mystery1 accounted for by divers theories1 none of which were right2 and the march of stars across the midnight sky was a complete puzzle2 and an eclipse of sun or moon was a fearful perplexity2 and the tides of ocean were a great bewilderment4 ,these things are mysteries still to barbarous nations2 but they perplex us no longer1 because we have found out the mode in which such movements1 or appearances of movement1 are brought about through the action of quite natural causes4 ,as a first step1 in earliest times1 the journey of the sun by day1 the journeys of moon and stars by night1 across the sky1 could hardly fail to arrest attention4 ,very early1 too1 the stars were grouped into constellations1 definite figures and names being attached to each4 ,many of the constellations are now known to us by names which belong to the earliest historic ages4 ,the stars were known as 8fixed10 because they continued unchangeably in their relative positions--that is1 in the position held by each star with respect to its neighbor stars--although the whole array of them moved nightly in company2 constellations rising and setting at night1 as the sun rose and set in the day4 ,ages may well have passed before the planets were recognized as distinct from the fixed stars2 ages more before any definite plan was noted in their wanderings4 ,in the course of time men's attention was directed to these matters2 and one fact after another1 of daily or monthly or yearly occurrence1 was observed1 and commented upon1 and became familiar to the minds of people4 ,very slowly the first beginnings of systematized knowledge took shape and grew1 one discovery being made after another1 one explanation being offered after another1 one theory being started after another4 ,but an essential difference existed between the infantine science of those primitive days and the matured astronomy of these later days4 ,the whole ancient science was built upon a huge mistake4 ,men held1 as a fact of absolutely unquestionable certainty1 that this earth of ours--this small whirling globe1 less than eight thousand miles in diameter--was the center1 around which sun1 moon1 and stars all revolved4 ,the ,greek philosopher ,thales1 who lived about six hundred years before ,christ1 is said to have laid the foundations of the ,grecian astronomy2 and ,pythagoras is stated to have been one of his disciples4 ,though1 in many respects1 ,thales wandered wide of the truth1 he yet taught many correct ideas2 as1 for instance1 that the stars were made of fire2 that the moon had all her light from the sun2 that the earth was a sphere in shape1 besides other facts respecting the earth's zones and the sun's apparent path in the sky4 ,he was also one of the three ancient astronomers who were able to calculate and foretell eclipses4 ,after him came numerous astronomers1 of greater or less merit1 in the ,grecian and in other schools4 ,they watched carefully2 they discovered many things of interest2 they held divers theories4 ,but one truth never took firm root among them1 although several of them dimly apprehended it2 and this was the very foundation-truth1 for lack of which they were all going hopelessly astray--the simple truth that our earth is not the center of the universe1 and that our earth does move4 ,yet it is not surprising4 ,no wonder they were slow to grasp such a possibility4 ,anything more bewildering to the mind of ancient man than the thought of a solid1 substantial world floating in empty space1 supported upon nothing1 upheld by nothing1 can hardly be imagined4 ,as yet little was known of the controlling laws or forces of nature1 and that little was with reference only to our earth4 ,the very suspicion of gravitation as a universal law lay in the far-distant future1 waiting for the intellect of a ,newton to call it out of apparent chaos2 and the delicate balance of forces1 by means of which the ,solar ,system may almost be said to exist1 could not be so much as guessed at4 ,so men still clung to the thought of earth as the center of all things1 and still believed in a little sun1 busily circling round her once in every twenty-four hours4 ,perhaps the greatest of all ancient astronomers was ,hipparchus1 about #aej ,b4 ,c41 who did more than any other in those early times to gather together the scattered facts of astronomy1 and to arrange them into one united and orderly whole4 ,he it was who discovered the precession of the equinoxes4 ,he studied eclipses and the motions of the various planets4 ,he made elaborate and valuable astronomical tables and star-catalogues2 but he1 like others1 failed to discover the gigantic error which lay at the root of the whole ancient science4 ,despite this great mistake1 still persistently believed in1 and despite the crude notions of early astronomers on many points1 it is marvelous how much they did manage to observe and to learn for themselves1--as to the sun and his apparent path1 as to the moon and her path1 as to the five then known planets and their paths1 as to eclipses and other phenomena4 ,by all such careful watching1 although they to some extent missed their aim and fell into mistakes1 yet they paved a way to later discoveries and to fuller knowledge4 ,their work was not thrown away1 their trouble was not lost2 for out of their very errors grew the fair form of truth4 ,nearly three hundred years after the time of ,hipparchus came the famous ,ptolemy--famous1 not1 like certain other astronomers1 for stupendous genius1 or for the brilliancy and accuracy of his observations1 but rather noted for the ingenuity of his explanations1 and for the adroit manner in which he systematized such knowledge1 on the subject of the heavenly bodies1 as was then in the possession of mankind4 ,ptolemy's name is best known in connection with what is commonly called 8,the ,ptolemaic ,system of the ,universe10 and his greatest astronomical work is best known as the ,almagest4 ,a great many of ,ptolemy's leading notions1 as well as the principal mass of facts upon which he worked1 were doubtless borrowed from ,hipparchus4 ,the latter is said to have explained the movements of the sun and of the moon by means of small epicycles1 traveling round the earth on circular orbits2 and even ,hipparchus did not originate this fundamental idea of the so-called 8,ptolemaic ,system10 which had indeed been held by the ancients in much earlier days4 ,hipparchus worked it out to some extent1 and ,ptolemy carried on the process much farther1 giving forth the system to the world in such wise that ever since it has gone by his name4 ,the theory of cycles and epicycles lasted long--lasted from the time of ,ptolemy in the second century to the time of ,copernicus in the sixteenth century1 of whom we have already spoken4 ,for about two thousand years1 astronomers observed attentively the apparent revolutions of the heavenly bodies1 and this attentive study gradually showed them a large number of irregularities and inexplicable complications1 until at last they recognized that they were deceived as to the earth's position1 in the same way that they had been deceived as to its stability4 ,the immortal ,copernicus1 in particular1 discussed with perseverance the earth's motion1 already previously suspected for two thousand years1 but always rejected by man's self-love2 and when this learned ,polish canon bid adieu to our world in the year #aedc1 he bequeathed to science his great work1 which demonstrated clearly the long-standing error of mankind4--,f4 ,the new theory of ,copernicus had to make its way slowly against the dead weight of unreasoning public opinion1 and against wrongly-reasoning hierarchical opposition4 ,in time1 gradually1 despite all resistance1 the truth made its way1 and was generally received1 though not till ,galileo had been forced by ecclesiastical authority to recant his opinions4 ,all the same1 ,copernicus1 ,kepler1 ,galileo1 were right2 public sentiment and the ,church were wrong1--the earth did move1 and was not the fixed universe center1 and1 by and by1 those who lived on earth had to acknowledge the same4 ,the succession of these great men is interesting to note4 ,between the two shining lights1 ,hipparchus and ,ptolemy1 nearly three hundred years intervened4 ,but as the history of the world advances1 we find brilliant scientific minds appearing more quickly1 one following close upon another1 instead of their being divided by long intervals of blankness4 ,within thirty years from the death of ,copernicus1 were born two mighty men of ,science3 ,kepler1 who lived till #afcj2 and ,galileo1 who lived till #afdb1 when ,england was plunged in civil strife4 ,between ,copernicus and ,kepler came ,tycho ,brahe4 ,copernicus was a ,roman ecclesiastic1 born in ,poland4 ,tycho ,brahe was a wealthy ,danish nobleman1 an ardent lover of astronomy1 and a most patient and accurate observer4 ,but ,tycho held fast by the old astronomy4 ,he was not convinced by the arguments of ,copernicus4 ,to him1 earth was still the motionless center of all things4 ,he was willing to allow that the rest of the planets circled round the sun1 as an explanation of things which he could not help seeing2 but the sun itself had still1 in ,tycho's imagination1 to revolve daily1 with planets and stars and the whole sky1 round our earth4 ,as an explainer of causes1 therefore1 ,tycho rose to no lofty heights4 ,the real good which he did was in watching and noting actual phenomena1 not in trying to explain how those phenomena were brought about4 ,this was left for one of his young pupils1 a sickly ,german lad1 named ,john ,kepler4 ,in later years1 ,kepler made a grand use of his master's mass of careful and thoroughly dependable observations4 ,these had really been gathered together by ,tycho1 with a view of disproving the ,copernican theory1 and of establishing the main features of the olden astronomy1 with certain improvements4 ,but ,kepler used the accumulated information to disprove the old astronomy1 and to establish the truth of the new ,copernican system which ,tycho had rejected4 ,he found a vast advantage1 ready to his hand1 in the collection of careful observations systematically worked out by ,tycho in his observatory during many a long year4 ,and ,kepler did not fail to use his advantage4 ,the planets still refused1 as they always had refused1 to keep to the paths marked out for them by astronomers4 ,kepler grappled with the difficulty4 ,he particularly turned his attention to ,mars1 that near neighbor of ours1 in which we are all now so much interested4 ,a long series of close observations of ,mars's movements1 made by ,tycho in the course of many years1 lay before him2 and he knew that he could depend upon the absolute honesty and accuracy of ,tycho's work4 ,with immense labor and immense patience1 he went into the matter1 still clinging to the old idea of a circular pathway round the sun4 ,he tried things this way and that way4 ,he placed his orbit in imagination after one mode and another mode2 he conjectured various arrangements2 he tested and proved them in turn1 comparing each plan with observations made1--and still ,mars defied all his efforts2 still the little world went persistently wrong1 traveling contrary to every theory4 ,thus far1 nobody had ever thought of an orbit of any other shape than a circle4 ,when a straightforward journey round a circle was found impossible1 then epicycles were introduced to explain the planet's perplexing motions4 ,no one had dreamt of an elliptic pathway4 ,but suddenly a gleam of daylight came upon this groping in the dark4 ,what if ,mars traveled round the sun--not in a circle1 but in an oval8 ,kepler tried this oval and that oval1 comparing observations past--testing1 examining1 proving or disproving1 with unwearied patience4 ,and at length he found1 beyond dispute1 that ,mars actually did travel round the sun in a yearly pathway1 which was shaped1 not as a circle1 but as the kind of oval known as an ellipse2 and1 further1 that the sun was not in the exact center of this ellipse1 but to one side of the center1 in one of the foci4 ,kepler's success in detecting the true shape of a planetary orbit is doubtless owing to the fact that the orbit of ,mars makes a wider departure from the circular form than any of the other important planets4 ,one step further would have led ,kepler to the knowledge that comets also travel in elliptic orbits--only in very long and narrow ones generally4 ,but he had quite made up his mind that all comets merely paid our sun one visit1 and never by any chance returned2 so he did not trouble himself to enter into calculations with respect to them4 ,this taking for granted of ideas long held was a very common practice in those days4 ,the above wonderful discovery of elliptic orbits1 in place of circular orbits1 was only one among many made by the illustrious ,kepler--discoveries not carelessly hit upon1 as one might pick up in the street a valuable stone which somebody had dropped1 but earnestly sought for1 and found with toil and diligence1 as gems are first found in foreign lands1 after much seeking and long patience4 ,casual discoveries in science are rare4 ,attainment is far more usually made through intense study1 through hard work1 through profound thought1 through a gradual groping upward out of darkness to the point where daylight breaks forth4 ,the three well-known 8,laws of ,kepler0 still lie at the very foundation of the modern system of astronomy4 ,they are3 ,first1 every planet moves in an elliptical orbit1 in one focus of which the sun is situated2 second1 the line drawn from the sun to a planet moves over equal areas in equal times2 and1 third1 the square of the periodic times of the planets varies inversely as the cubes of their distances4 ,,chapter ,,xxxiii4 ,,modern ,,astronomy4 ,still1 however1 the world was not convinced of the truth of the ,copernican system4 ,one man here or there saw and acknowledged its reality4 ,the mass of mankind continued firmly to believe that they dwelt at the universe center1 and utterly to scout the idea of a moving earth4 ,indeed1 it may be very much doubted whether1 not merely the mass of mankind1 but even the most civilized and cultivated portion of that mass1 had as yet1 to any wide extent1 heard a whisper of the new theories4 ,knowledge1 in those days1 traveled from place to place with exceeding deliberation4 ,another great man arose1 contemporary with ,kepler--a man whose story seizes more strongly upon our imagination than that of the severe and successful studies of ,kepler4 ,from an ordinary worldly point of view1 ,kepler would hardly be looked upon as altogether a successful man4 ,he was poor1 and in sickly health4 ,his chief book was promptly prohibited by ,rome--then a power in the whole reading world of ,europe to an extent which can hardly be realized in these days of freedom4 ,kepler's book was placed in the forbidden category1 side by side with the dying publication of ,copernicus4 ,this checked all hope of literary gains1 and life with ,kepler was one long struggle4 ,but if he could have looked ahead two or three hundred years2 if he could have foreseen the time when not a few wise men of science alone1 but all the civilized world1 including the very ,church which condemned him1 should meekly have accepted and indorsed his discoveries1--then he would have been able to gauge the measure of his own real success4 ,moreover1 with all his troubles1 ,kepler was so happy as to escape absolute persecution4 ,he lived in a country which knew something of liberty as an ideal2 he was left to write and work freely2 and1 at least1 no public recantation of what he held to be truth was forced from him4 ,galileo's was a sadder tale4 ,a ,florentine of noble birth1 he turned his attention early to science as the needle turns to the north1 and before the age of twenty-seven he already occupied a foremost position as mathematical lecturer at ,pisa4 ,there it was that he direfully offended the philosophers of the day by proving ,aristotle to be in the wrong4 ,for ,aristotle was the great master of the schoolmen4 ,his philosophy and theories were accepted as final1 and whatsoever could not be proved in accordance with them was regarded as untrue4 ,aristotle had declared that if two weights--the one being ten times as heavy as the other--were dropped together from a height1 the heavier weight would reach the ground ten times as quickly as the lighter4 ,everybody believed this1 and nobody had ever thought of putting it to the test of actual trial4 ,aristotle had said so1 and ,aristotle was indorsed as a whole by all the schools of ,europe2 and what more could possibly be wanted by any reasonable human being8 ,but ,galileo was not so easily satisfied4 ,he looked into the matter independently1 bent upon finding out1 not what ,aristotle had thought or what the ,church might support1 but simply what actually was4 ,illustration3 ,,prominent ,,astronomers ,,of ,,the ,,nineteenth ,,century4 ,then1 in view of many observers1 called together for the occasion1 he dropped1 at the same instant1 from the top of the leaning tower of ,pisa1 a shot weighing one pound and another shot weighing a hundred pounds4 ,and1 behold6 both reached the ground simultaneously4 ,there was not a fraction of difference between the two4 ,to prove ,aristotle wrong was to prove everybody wrong1 the authorities of the ,church included4 ,men calmly declined to believe their own eyes1 and ,galileo was in very evil odor4 ,from falling bodies he went on to subjects of yet wider interest to people in general4 ,he read about and eagerly embraced the ,copernican system4 ,not only did he accept it himself1 but he vigorously set to work to teach and convince others also4 ,this1 as might only be expected1 aroused vehement opposition4 ,but ,galileo was still in the heyday of his powers1 and he was not to be easily silenced4 ,in those days he could afford to press onward in the teeth of resistance1 and to laugh at men who would not listen4 ,when at ,venice1 a report reached him of a certain optician in ,holland who had happened to hit upon a curious 8combination of lenses10 through which objects afar off could be actually seen as if they were near4 ,galileo promptly seized upon the notion1 and within twenty-four hours he had rigged up a small1 rough telescope out of an old organ-pipe and two spectacle-glasses4 ,thus the first telescope was made--a very elementary affair1 formed of two lenses1 convex and concave1 and capable of magnifying some three times--a mere child's toy compared with telescopes of the present day1 but of exceeding value and interest1 because it was the very first2 because in all the history of the world no telescope had ever been manufactured before4 ,this earliest effort was speedily improved upon4 ,the next trial produced a tube which could magnify seven or eight times2 and in a little while1 ,galileo had a telescope magnifying as much as thirty-two times4 ,even thirty-two times does not sound very startling to us2 but in those days the revelations of such an instrument came upon men like a thunderclap4 ,through it could be seen clearly the broken nature of the moon's surface--the craters1 the shadows1 the mountains4 ,through it could be seen the phases of ,venus1 which no man had ever yet detected1 but which ,copernicus had declared must certainly exist1 if indeed his system were a reality4 ,through it could be seen four of the moons of ,jupiter1 and their ceaseless journeyings4 ,through it could be seen spots upon the face of the sun1 the movements of which showed the rotation of the sun upon his axis4 ,through it could be seen the very curious shape of ,saturn1 caused by his rings1 though a much stronger power was needed to separate the rings from the body of the planet4 ,of all these discoveries1 and many others also made by ,galileo1 none seemed worse to the bigoted schoolmen of his day than the preposterous notion of black spots upon the sun's face4 ,rather curiously1 no human being seems ever before then to have noticed such spots1 though often they are quite large enough to be detected by the naked eye4 ,a general belief had been held that the sun was and must be perfect--an absolutely spotless and unblemished being1 the purest symbol of celestial incorruptibility--and the said discovery went right in the teeth of deductions drawn from1 and lessons founded upon1 this belief4 ,therefore the schoolmen held out and determinedly resisted1 and would have nought to do with ,galileo or his telescopes1 shutting their eyes to marvels newly revealed4 ,but ,kepler was a true scientist1 a man who earnestly pursued truth1 and sought to discover it at any hazard4 ,he and ,galileo were contemporaries1 and they held communication on these subjects4 ,some of ,galileo's discoveries went quite as much in the teeth of some of ,kepler's most dearly-loved theories as they did in the teeth of the schoolmen's most dearly-loved doctrines4 ,yet1 none the less1 ,kepler welcomed them with great delight and eagerness1 showing thereby his true greatness of character4 ,till after the age of fifty1 ,galileo was allowed to go on undisturbed1 or at least not materially disturbed1 by opposition in his career of success--observing1 learning1 theorizing1 calculating1 explaining1 teaching--a prominent figure indeed4 ,not only did he take a large share in establishing firmly the ,copernican system of astronomy1 but some of the principal laws of motion were discovered by him4 ,he first found the uses of a pendulum1 and there is strong reason for believing that the first microscope1 as well as the first telescope1 was from his hands4 ,but after the age of fifty1 reverses came1 and one blow succeeded another4 ,rome had been gradually waking up to the true sense of all that was implied by his discoveries and his teaching1 and at length she let loose her thunders--impotent thunders enough1 so far as regarded any permanent checking of the progress of truth1 but by no means impotent to crush one defenseless victim1 the champion of scientific truth in that country and age4 ,years of greater or less opposition1 amounting often to persecution1 were followed by an imperious order commanding him to ,rome4 ,there he was examined and severely 8questioned10 and recantation was forced from him1 worth as much as such forced recantations commonly are worth4 ,even then he did not cease from the work that he loved2 even in prison he carried it on2 even when he might not write1 nothing could stop him from thinking4 ,but his health was broken2 his liberty was taken away2 illness followed illness2 his favorite daughter died2 his eyesight gradually failed2 the last book that he wrote might not for a long while be printed2 and at last he passed away1 mercifully set free from those who1 in an essentially bigoted and intolerant age1 were incapable of appreciating his greatness4 ,they would fain then have denied him even a respectable grave4 ,now1 all the civilized world unites to honor the name of ,galileo4 ,,chapter ,,xxxiii4 ,,isaac ,,newton4 ,even the great fame of ,galileo must be relegated to a second place in comparison with that of the philosopher who first saw the light in a ,lincolnshire farmhouse on the #beth of ,december1 #afdb1 the very same year of ,galileo's death4 ,his father1 ,isaac ,newton1 had died before his birth4 ,the little ,isaac was at first so frail and weakly that his life was despaired of4 ,the watchful mother1 however1 tended her delicate child with such success that he ultimately acquired a frame strong enough to outlast the ordinary span of human life4 ,in due time the boy was sent to the public school at ,grantham4 ,that he might be near his work1 he was boarded at the house of ,mr4 ,clark1 an apothecary4 ,he had at first a very low place in the class4 ,his first incentive to diligent study seems to have been derived from the circumstance that he was severely kicked by one of the boys above him in the class4 ,this indignity had the effect of stimulating young ,newton's activity to such an extent that he not only attained the desired object of passing over the head of the boy who had maltreated him1 but continued to rise until he became the head of the school4 ,the play-hours of the great philosopher were devoted to pursuits very different from those of most schoolboys4 ,his chief amusement was found in making mechanical toys1 and various ingenious contrivances4 ,he watched1 day by day1 with great interest1 the workmen engaged in constructing a windmill in the neighborhood of the school1 the result1 of which was that the boy made a working model of the windmill and of its machinery1 which seems to have been much admired as indicating his aptitude for mechanics4 ,we are told that he also indulged in somewhat higher flights of mechanical enterprise4 ,the first philosophical instrument he made was a clock1 which was actuated by water4 ,he also devoted much attention to the construction of paper kites1 and his skill in this respect was highly appreciated by his schoolfellows4 ,like a true philosopher1 even at this stage1 he experimented on the best methods of attaching the string1 and on the proportions which the tail ought to have4 ,when the schoolboy at ,grantham was fourteen years of age1 it was thought necessary to recall him from the school4 ,his recently-born industry had been such that he had already made good progress in his studies1 and his mother hoped that he would now lay aside his books1 and those silent meditations to which1 even at this early age1 he had become addicted4 ,it was hoped that instead of such pursuits1 which were deemed quite useless1 the boy would enter busily into the duties of the farm and the details of a country life4 ,but before long it became manifest that the study of nature and the pursuit of knowledge had such a fascination for the youth that he could give little attention to aught else4 ,it was plain that he would make but an indifferent farmer4 ,he greatly preferred experimenting on water-wheels1 and working at mathematics in the shadow of a hedge4 ,fortunately for humanity1 his mother1 like a wise woman1 determined to let her boy's genius have the scope which it required4 ,he was accordingly sent back to ,grantham school1 with the object of being trained in the knowledge which would fit him for entering the ,university of ,cambridge4 ,it was the #eth of ,june1 #affj1 when ,isaac ,newton1 a youth of eighteen1 was enrolled as an undergraduate of ,trinity ,college1 ,cambridge4 ,little did those who sent him there dream that this boy was destined to be the most illustrious student who ever entered the portals of that great seat of learning4 ,little could the youth himself have foreseen that the rooms near the gateway which he occupied would acquire a celebrity from the fact that he dwelt in them1 or that the antechapel of his college was in good time to be adorned by that noble statue of himself which is regarded as the chief art treasure of ,cambridge ,university1 both on account of its intrinsic beauty and the fact that it commemorates the fame of her most distinguished alumnus1 ,isaac ,newton1 the immortal astronomer4 ,his advent at the university seemed to have been by no means auspicious or brilliant4 ,his birth was1 as we have seen1 comparatively obscure1 and though he had already given indication of his capacity for reflecting on philosophical matters1 yet he seems to have been but ill-equipped with the routine knowledge which youths are generally expected to take with them to the universities4 ,from the outset of his college career1 ,newton's attention seems to have been mainly directed to mathematics4 ,here he began to give evidence of that marvelous insight into the deep secrets of nature which1 more than a century later1 led so dispassionate a judge as ,laplace to pronounce ,newton's immortal work as pre-eminent above all the productions of the human intellect4 ,but though ,newton was one of the very greatest mathematicians that ever lived1 he was never a mathematician for the mere sake of mathematics4 ,he employed his mathematics as an instrument for discovering the laws of nature4 ,his industry and genius soon brought him under the notice of the university authorities4 ,it is stated in the university records that he obtained a scholarship in #affd4 ,two years later we find that ,newton1 as well as many residents in the university1 had to leave ,cambridge temporarily on account of the breaking out of the plague4 ,the philosopher retired for a season to his old home at ,woolsthorpe1 and there he remained until he was appointed a ,fellow of ,trinity ,college1 ,cambridge1 in #affg4 ,from this time onwards1 ,newton's reputation as a mathematician and as a natural philosopher steadily advanced1 so that in #affi1 while still but twenty-seven years of age1 he was appointed to the distinguished position of professor of ,mathematics at ,cambridge4 ,here he found the opportunity to continue and develop that marvelous career of discovery which formed his life's work4 ,the earliest of ,newton's great achievements in natural philosophy was his detection of the composite character of light4 ,that a beam of ordinary sunlight is1 in fact1 a mixture of a very great number of different colored lights1 is a doctrine now familiar to every one who has the slightest education in physical science4 ,we must1 however1 remember that this discovery was really a tremendous advance in knowledge at the time when ,newton announced it4 ,illustration3 ,,sir ,,isaac ,,newton4 ,a certain story is often told about ,newton4 ,it is said that as he sat in a garden an apple fell from a tree1 and that its fall set him thinking1 and that1 in consequence of this train of thought1 he found out all about the law of attraction or gravitation4 ,but the fall of an apple could not possibly have set ,newton thinking1 because he had already been thinking long and hard upon these difficult questions4 ,indeed1 it was because he had been so thinking1 because his mind was in a watchful and receptive condition1 that so slight a matter as a falling apple should1 perhaps1 have suggested to him a useful train of ideas4 ,newton was a man who really did think1 and who really did think intensely4 ,he was not1 like the ordinary run of people1 one who merely had a good many notions walking loosely through his brain4 ,he would bend his mind to a subject and be absolutely absorbed in it2 later in life so absorbed that he would forget to finish his dressing1 and would be unable to say whether or no he had dined4 ,this sort of forgetfulness does sometimes spring from vacancy of mind2 but with ,newton it arose from fullness of thought4 ,an apple falls1 of course1 as a stone or any other body falls1 because the earth attracts it4 ,otherwise1 it might as easily rise and float away into the sky4 ,but this was known perfectly well long before ,newton's days4 ,it was clearly understood that the earth had a curious power of drawing all things towards herself4 ,people could not explain why or how it was so2 neither can we explain now2 but they were fully aware of the fact4 ,so men knew something of the force called gravity2 but they knew it mainly1 almost exclusively1 as having to do with our earth1 and with the things upon our earth4 ,they had not begun definitely to think of gravity as having to do with bodies in the heavens2 as being a chief controlling force in the whole ,solar ,system2 much less as reigning throughout the vast universe of stars4 ,it had not come into their minds with any distinctness that1 just as the earth pulls towards her own center a mountain1 a horse1 a man1 so the sun pulls toward his center the earth1 the moon1 and all the planets4 ,certain glimmerings of the notion had1 indeed1 begun to dawn on the horizon of learning4 ,horrocks1 ,borelli1 ,robert ,hook1 ,wren1 ,halley1 and others had glimpses of universal gravitation2 but only glimpses4 ,a gifted ,english philosopher1 late in the sixteenth century1 ,gilbert by name1 went so far as to speak of earth and moon acting one upon the other 8like two magnets40 ,he also saw the effect of the moon's attraction in bringing about ocean tides1 though he oddly explained that the said attraction was not so much exerted upon ocean waters as upon 8subterranean spirits and humors0--whatever he may have meant by such an expression4 ,kepler1 not long after ,gilbert1 made further advance4 ,he gained some definite notions as to the nature of gravity2 and he saw distinctly that the moon's attraction was the main cause of the tides4 ,the following remarkable statement is found in his writings3 8,if the earth ceased to attract its waters1 the whole sea would mount up and unite itself with the moon4 ,the sphere of the attracting force of the moon extends even to the earth1 and draws the waters towards the torrid zone1 so that they rise to the point which has the moon in the zenith40 ,here is a distinct enough grasp of the fact that gravity can and does act through distance1 between worlds separated by thousands of miles4 ,yet1 though both ,gilbert and ,kepler saw so much1 they failed to go farther4 ,neither of the two had any clear knowledge of the modes in which gravitation acts1 or of the laws which govern its working4 ,gilbert and ,kepler alike1 while dimly recognizing1 not only the moon's attraction for earth's oceans1 but the mutual attraction of earth and moon each for the other1 were utterly perplexed as to what force could possibly hold the two bodies asunder4 ,gilbert could seriously talk of 8subterranean spirits and humors40 ,kepler could soberly write of an 8animal force0 or some tantamount power in the moon1 which prevented her nearer approach to earth4 ,galileo was equally vague on the subject4 ,with all his brilliant gifts1 and while acknowledging the earth's attractive power over the moon1 he would not even admit the existence of mutual attraction1 and talked of the moon as being compelled to 8follow the earth40 ,unquestionably there are times when the moon does follow the earth1 and that is when the earth happens to go before4 ,but quite as often it happens that the moon goes before1 and the earth follows after4 ,all these great men were groping near the truth1 yet none managed to find the clue that was wanted4 ,they left the unfinished process of thought to be carried on by the master-mind of ,newton4 ,and ,newton set himself to think the question out4 ,he used ,kepler's observations4 ,he sought to penetrate the secrets of a ,solar ,system in mysterious and inviolable order4 ,some reason or cause for that order he knew must exist--if only it might be grasped6 ,he pondered deeply2 lost in profound cogitation1 through stormy days of civil strife1 of plague and loss and suffering4 ,the object of his life was to discover1 if so he might1 what power or what forces retained the different worlds in their respective pathways2 in short1 what manner of celestial guidance was vouchsafed to the planets4 ,for although men had now learned the shape of the planet-orbits1 and even knew certain laws which helped to govern the planet-motions1 they had not discovered one supreme controlling law4 ,they did not dream of gravity in the heavens as a prevailing force4 ,there was absolutely no reason1 with which men were acquainted1 why each planet should preserve its own particular distance from the sun2 why ,mars should not wander as far away as ,jupiter2 why ,mercury should not flee to the position of ,saturn2 why our own earth should be always about as near as she always is4 ,the resources of ,newton's genius seemed equal to almost any demand that could be made upon it4 ,he saw that each planet must disturb the other1 and in that way he was able to render a satisfactory account of certain phenomena which had perplexed all preceding investigators4 ,that mysterious movement by which the pole of the earth sways about among the stars1 had been long an unsolved enigma2 but ,newton showed that the moon grasped with its attraction the protuberant mass at the equatorial regions of the earth1 and thus tilted the earth's axis in a way that accounted for the phenomenon which had been known1 but had never been explained1 for two thousand years4 ,all these discoveries were brought together in that immortal work1 ,newton's 8,principia10 the greatest work on science that the world had yet seen4 ,it may well be that1 as ,newton pondered this perplexing question while seated in the garden1 an apple dropping to the ground might have sufficed to turn his wide-awake and ready mind in the direction of that familiar force1 gravity1 which draws all loose bodies towards earth's surface4 ,the apple fell because of gravity4 ,quite naturally the question might have arisen in ,newton's mind--8,why not this same gravity in the heavens also8 ,if the earth draws an apple towards herself1 why should not the earth draw the moon8 ,why should not the sun draw the earth8 ,nay1 more1 why should not the sun draw all the planets80 ,newton set himself to work out this problem1 allowing for the distance of the moon from earth1 and for the bulk and weight of both earth and moon4 ,and because the answer was not precisely what he had looked for1 he put the calculation aside1 and waited for years4 ,it seems that he mentioned his conjecture to no living person4 ,after many years he took it up again1 and worked it out afresh4 ,by this time new measurements of earth's surface1 and new calculations of earth's size had been made1 and ,newton had fresh figures to go upon4 ,this time the answer came just as he had originally hoped1 and the truth of his surmise was thus proved4 ,gravity held the moon near the earth1 preventing her from wandering off into unknown distances4 ,gravity held earth and moon1 ,mars1 ,venus1 ,jupiter1 each planet1 in its own pathway1 within a certain distance of the sun4 ,gravity held many of the comets as permanent members of the ,solar ,system4 ,so strong1 indeed1 was the drawing of gravity found to be1 that only the resisting force of each bright world's rapid rush round the sun could keep the sun and his planets apart4 ,newton had discovered the long-sought secret4 ,he had found that 8every particle of matter in the universe attracts every other particle80 ,he had found also the main laws which govern the working of that attraction--that it depends1 first1 upon the mass or amount of 8matter0 in each body2 that it depends1 secondly1 upon the distance of one body from another4 ,he found1 too1 how far attraction increases with greater nearness1 and decreases with greater distance4 ,all these and countless other questions he worked out in the course of years4 ,but first he had grasped the great leading principle1 after which men had until then groped in vain1 that by the force of gravity the sun and his worlds and their moons are all bound together into one large united family or system4 ,though ,newton lived long enough to receive the honor that his astonishing discoveries so justly merited1 and though for many years of his life his renown was much greater than that of any of his contemporaries1 yet it is not too much to say that1 in the years which have since elapsed1 ,newton's fame has been ever steadily advancing4 ,we hardly know whether to admire more the sublime discoveries at which he arrived1 or the extraordinary character of the intellectual processes by which those discoveries were reached4 ,he died on ,monday1 ,march #bj1 #agbg1 in the eighty-fifth year of his age4 ,,chapter ,,xxxv4 ,,later ,,astronomy4 ,sir ,william ,herschel was born in the city of ,hanover1 ,november #ae1 #agch4 ,he was the second son of ,isaac ,herschel1 a musician1 who brought him up1 with his four other sons1 to his own profession4 ,a faithful chronicler has given us an interesting account of the way in which ,isaac ,herschel educated his boys2 the narrative is taken from the recollections of one who1 at the time1 was a little girl of five or six years old4 ,she writes3 8,my brothers were often introduced as solo performers and assistants in the orchestra at the court1 and ,i remember that ,i was frequently prevented from going to sleep by the lively criticisms on music on coming from a concert4 ,often ,i would keep myself awake that ,i might listen to their animated remarks1 for it made me happy to see them so happy4 ,but generally their conversation would branch out on philosophical subjects1 when my brother ,william and my father often argued with such warmth that my mother's interference became necessary when the names ,euler1 ,leibnitz1 and ,newton sounded rather too loud for the repose of her little ones1 who had to be at school by seven in the morning40 ,the child1 whose reminiscences are here given1 became afterwards the famous ,caroline ,herschel4 ,the narrative of her life is a most interesting book1 not only for the account it contains of the remarkable woman herself1 but also because it presents the best picture we have of the great astronomer1 to whom ,caroline devoted her life4 ,this modest family circle was1 in a measure1 dispersed at the outbreak of the ,seven ,years' ,war in #agef4 ,the ,french proceeded to invade ,hanover1 which1 it will be remembered1 belonged at this time to the ,british dominions4 ,young ,william ,herschel had already obtained the position of a regular performer in the regimental band of the ,hanoverian ,guards1 and it was his fortune to obtain some experience of actual warfare in the disastrous battle of ,hastenbeck4 ,he was not wounded1 but he had to spend the night after the battle in a ditch1 and his meditations on the occasion convinced him that soldiering was not the profession exactly suited to his tastes4 ,he left his regiment by the very simple1 but somewhat risky1 process of desertion4 ,he had1 it would seem1 to adopt disguises in order to effect his escape4 ,by some means he succeeded in eluding detection1 and reached ,england in safety4 ,the young musician must have had some difficulty in providing for his maintenance during the first few years of his abode in ,england4 ,it was not until he had reached the age of twenty-two that he succeeded in obtaining any regular appointment4 ,he was then made instructor of music to the ,durham ,militia4 ,shortly afterwards1 his talents being more widely recognized1 he was appointed as organist of the parish ,church at ,halifax4 ,in #agff we find that ,herschel had received the further promotion of organist in the ,octagon ,chapel1 at ,bath4 ,bath was then1 as now1 a highly fashionable resort1 and many notable personages patronized the rising musician4 ,herschel had other points in his favor besides his professional skill2 his appearance was striking1 his address superb1 and his conversation animated1 interesting1 and instructive2 and even his nationality was a distinct advantage1 inasmuch as he was a ,hanoverian in the reign of ,king ,george the ,third4 ,from his earliest youth1 ,herschel had been endowed with that invaluable characteristic1 an intense desire for knowledge4 ,he naturally wished to perfect himself in the theory of music1 and thus he was led to study mathematics4 ,when he had once tasted the charms of mathematics1 he saw vast regions of knowledge unfolded before him1 and in this way he was induced to direct his attention to astronomy4 ,more and more this pursuit engrossed his attention until1 at last1 it had become an absorbing passion4 ,it was with quite a small telescope1 which had been lent him by a friend1 that ,herschel commenced his career as an observer4 ,however1 he speedily discovered that to see all he wanted to see1 a telescope of far greater power would be necessary4 ,he commissioned a friend to procure for him in ,london a telescope with high magnifying power4 ,fortunately for science the price was so great that it precluded the purchase1 and he set himself at work to construct one4 ,after many trials he succeeded in making a reflecting instrument of five feet focal length1 with which he was able to observe the rings of ,saturn and the satellites of ,jupiter4 ,it was in #aggd1 when the astronomer was thirty-six years old1 that he obtained his first glimpse of the stars with an instrument of his own construction4 ,night after night1 as soon as his musical labors were ended1 his telescopes were brought out4 ,his sister ,caroline1 who occupies such a distinct place in scientific history1 the same little girl to whom we have already referred1 was his able assistant1 and when mathematical work had to be done1 she was ready for it4 ,she had taught herself sufficiently to enable her to perform the kind of calculations--not1 perhaps1 very difficult ones--that ,herschel's work required2 indeed1 it is not much to say that the mighty life-work which this man was enabled to perform could never have been accomplished had it not been for the self-sacrifice of this ever-loving and faithful sister4 ,it was not until #aghb that the great achievement took place by which ,herschel at once sprang into fame4 ,he appears to have formed a project for making a close examination of all the stars above a certain magnitude for the purpose of discovering1 if possible1 a parallax among them4 ,star after star was brought to the center of the field of view of his telescope1 and after being carefully examined1 was then displaced1 while another star was brought forward to be submitted to the same process4 ,in the great review which ,herschel undertook1 he doubtless examined hundreds1 or perhaps thousands of stars1 allowing them to pass away without note or comment4 ,but on an ever-memorable night in ,march1 #aghb1 it happened that he was pursuing his task among the stars in the constellation of ,gemini4 ,one star was noticed which1 to ,herschel's acute vision1 seemed different from the stars which in so many thousands are strewn over the sky4 ,there was something in the starlike object that immediately arrested his attention1 and made him apply to it a higher magnifying power4 ,this at once disclosed the fact that the object possessed a disk--that is1 a definite1 measurable size--and that it was thus totally different from any of the hundreds and thousands of stars which exist elsewhere in space4 ,the organist at the ,octagon ,chapel at ,bath had discovered a new planet with his home-made telescope4 ,great was the astonishment of the scientific world when the ,bath organist announced that the five planets1 which had been known from all antiquity1 must now admit the company of a sixth4 ,the now great astronomer was invited to ,windsor1 and to bring his famous telescope in order to exhibit the planet to ,george ,,iii1 and to tell his majesty all about it4 ,the king took so great a fancy to ,herschel that he proposed to confer on him the title of 8his majesty's own astronomer10 to assign him a residence near ,windsor1 to provide him with a salary1 and to furnish such funds as might be required for the erection of great telescopes1 and for the conduct of that mighty scheme of celestial observation on which ,herschel was so eager to enter4 ,no single discovery of ,herschel's later years was1 however1 of the same momentous description as that which first brought him to fame4 ,there is no separate collection of his writings1 and very scanty accounts of his life have been published2 but he who has written his name among the stars needs no other testimonial to his fame4 ,prior to his time the number of bodies known as belonging to the ,solar ,system was eighteen1 including secondary planets and ,halley's comet4 ,to these he added nine2 namely1 ,uranus and six satellites1 and two satellites of ,saturn4 ,though no additional honors could add to his fame1 ,dr4 ,herschel1 in #ahaf1 received the decoration of the ,guelphic ,order of ,knighthood4 ,in #ahbj he was elected president of the ,astronomical ,society1 and among their ,transactions1 the next year1 he published an interesting memoir on the places of one hundred and forty-five double-stars4 ,this paper was the last which he lived to publish4 ,his health had begun to decline1 and on the #bdth of ,august1 #ahbb1 he sank under the infirmities of age1 having completed his eighty-fourth year4 ,he was survived by his widow1 ,lady ,herschel1 an only son1 ,sir ,john ,f4 ,w4 ,herschel1 and his sister ,caroline1 who died in #ahdg1 in her ninety-eighth year4 ,,laplace4 ,the author of 8,celestial ,mechanics0 was born at ,beaumont-en-,auge in #agdi1 just thirteen years later than his renowned friend ,lagrange4 ,his father was a farmer1 but appears to have been in a position to provide a good education for a son who seemed promising4 ,the subject which first claimed his attention was theology4 ,he was1 however1 soon introduced to the study of mathematics1 in which he presently became so proficient that1 while he was still no more than eighteen years old1 he obtained employment as a mathematical teacher in his native town4 ,desiring wider opportunities for study1 young ,laplace started for ,paris1 being provided with letters of introduction to ,d',alembert1 who then occupied the most prominent positions as a mathematician in ,france1 if not in ,europe4 ,on presenting these letters1 he seems to have had no reply2 whereupon1 ,laplace wrote to ,d',alembert1 submitting a discussion of some point in dynamics4 ,this letter instantly produced the desired effect4 ,d',alembert thought that such mathematical talent as the young man displayed was in itself the best of introductions to his favor4 ,it could not be overlooked1 and accordingly he invited ,laplace to come and see him4 ,laplace1 of course1 presented himself1 and erelong ,d',alembert obtained for the rising philosopher a professorship of ,mathematics in the military school in ,paris4 ,this gave the brilliant young mathematician the opening for which he sought1 and he quickly availed himself of it4 ,laplace's most famous work is 8,celestial ,mechanics10 in which he essayed a comprehensive attempt to carry out1 in much greater detail1 the principles which ,newton had laid down4 ,the fact was that ,newton had not only to construct the theory of gravitation1 but he had to invent the mathematical processes by which his theory could be applied to the explanation of the movements of the heavenly bodies4 ,in the course of the century which had elapsed between the time of ,newton and the time of ,laplace1 mathematics had been extensively developed4 ,the disturbances which one planet exercises upon the rest can only be fully ascertained by the aid of long calculations1 and for these calculations analytical methods are required4 ,with an armament of mathematical methods which had been perfected since the days of ,newton by the labors of two or three generations of mathematical inventors1 ,laplace essayed in his 8,celestial ,mechanics0 to unravel the mysteries of the heavens4 ,it will hardly be disputed that the book which he has produced is one of the most difficult books to understand that has ever been written4 ,the investigations of ,laplace are1 generally speaking1 of too technical a character to make it possible to set forth any account of them in such a work as the present4 ,he did1 however1 publish one treatise1 called the 8,system of the ,universe10 in which1 without introducing mathematical symbols1 he was able to give a general account of the theories of the celestial movements1 and of the discoveries to which he and others had been led4 ,in this work ,laplace laid down the principles of the nebular theory1 which1 in modern days1 has been generally accepted4 ,the nebular theory gives a physical account of the origin of the ,solar ,system1 and has already been explained in this volume4 ,bach advance in science seems to make it more certain that this hypothesis substantially represents the way in which our ,solar ,system has grown to its present form4 ,not satisfied with a career which was merely scientific1 ,laplace sought to connect himself with public affairs4 ,napoleon appreciated his genius1 and desired to enlist him in the service of the state4 ,laplace was appointed to the office of minister of the interior4 ,the experiment was not successful1 for he was not by nature a statesman4 ,in despair of ,laplace's capacity as an administrator1 ,napoleon declared that he carried the spirit of his infinitesimal calculus into the management of business4 ,indeed1 ,laplace's political conduct hardly admits of much defense4 ,while he accepted the honors which ,napoleon showered on him in the time of his prosperity1 he seems to have forgotten all this when ,napoleon could no longer render him service4 ,laplace was made a marquis by ,louis ,,xviii4 ,during the latter part of his life the philosopher lived in a retired country-place at ,arcueile4 ,here he pursued his studies1 and1 by strict abstemiousness1 preserved himself from many of the infirmities of old age4 ,he was endowed with remarkable scientific sagacity2 but above all his powers his wonderful memory shone pre-eminent4 ,his 8,celestial ,mechanics0 is1 next to ,newton's 8,principia10 the greatest of astronomical works4 ,he died on ,march #e1 #ahbg1 in his seventy-eighth year1 his last words being1 8,what we know is but little1 what we do not know is immense40 ,,leverrier4 ,we are apt to identify the idea of an astronomer with that of a man who looks through a telescope at the stars2 but the word astronomer has really a much wider significance4 ,no man who ever lived has been more entitled to be designated an astronomer than ,urbain ,jean ,joseph ,leverrier1 and yet it is certain that he never made a telescopic discovery of any kind4 ,in mathematics1 however1 he excelled1 and he simply used the observations of others as the basis of his calculations4 ,these observations form1 as it were1 the raw material on which the mathematician exercises his skill4 ,it is for him to elicit from the observed places the true laws which govern the movements of the heavenly bodies4 ,here is indeed a task in which the highest powers of the human intellect may be worthily employed4 ,to ,leverrier it has been given to provide a superb illustration of the success with which the mind of man can penetrate the deep things of nature4 ,the illustrious ,frenchman was born on the #aath of ,march1 #ahaa1 at ,saint-,l1 in the department of ,manche4 ,in the famous polytechnic school for education in the higher branches of science he acquired considerable fame as a mathematician4 ,his labors at school had revealed to ,leverrier that he was endowed with the powers requisite for dealing with the subtlest instruments of mathematical analysis4 ,when he was twenty-eight years old his first great astronomical investigation was brought forth4 ,this was the profound calculation of the disturbances of the planet ,uranus and the causes of them4 ,the talent which his researches displayed brought ,leverrier into notice4 ,at that time the ,paris ,observatory was presided over by ,arago1 a savant who occupies a distinguished position in ,french scientific annals4 ,arago at once perceived that ,leverrier possessed the qualifications suitable for undertaking a problem of great importance and difficulty that had begun to force itself on the attention of astronomers4 ,what this great problem was1 and how astonishing was the solution it received1 must now be considered4 ,ever since ,herschel brought himself into fame by the discovery of ,uranus1 the movements of this new addition to the ,solar ,system had been scrutinized with care and attention4 ,the position of ,uranus was thus accurately determined from time to time4 ,when due allowance was made for whatever influence the attraction of ,jupiter and ,saturn and all the other planets could possibly produce1 the movements of ,uranus were still inexplicable4 ,it was perfectly obvious that there must be some other influence at work besides that which could be attributed to the planets already known4 ,astronomers could only recognize one solution of such a difficulty4 ,it was impossible to doubt that there must be some other planet in addition to the bodies at that time known1 and that the perturbations of ,uranus1 hitherto unaccounted for1 were due to the disturbances caused by the action of this unknown planet4 ,arago urged ,leverrier to undertake the great problem of searching for this body4 ,but the conditions of the search were such that it must be conducted on principles wholly different from any search which had ever before been undertaken for a celestial object4 ,for this was not a case in which mere survey with a telescope might be expected to lead to the discovery4 ,there are in the heavens many millions of stars1 and the problem of identifying the planet1 if indeed it should lie among these stars1 seemed a very complex matter4 ,of course1 it is the abundant presence of the stars which causes the difficulty4 ,the materials available to the mathematician for the solution of this problem were to be derived solely from the discrepancies between the calculated places in which ,uranus should be found1 taking into account the known causes of disturbances1 and the actual places in which observation had shown the planet to exist4 ,here was1 indeed1 an unprecedented problem1 and one of extraordinary difficulty4 ,leverrier1 however1 faced it1 and1 to the astonishment of the world1 succeeded in carrying it through to a brilliant solution4 ,after many trials1 ,leverrier ascertained that1 by assuming a certain size1 shape1 and position for the unknown planet's orbit1 and a certain value for the mass of the hypothetical body1 it would be possible to account for the observed disturbances of ,uranus4 ,gradually it became clear to his perception1 not only that the difficulties in the movements of ,uranus could be thus explained1 but that no other explanation need be sought for4 ,and now for an episode in this history which will be celebrated so long as science shall endure4 ,it is nothing less than the telescopic confirmation of the existence of this new planet1 which had previously been indicated only by mathematical calculation4 ,great indeed was the admiration of the scientific world at this superb triumph4 ,here was a mighty planet1 whose very existence was revealed by the indications afforded by refined mathematical calculation4 ,at once the name of ,leverrier1 already known to those conversant with the more profound branches of astronomy1 became everywhere celebrated4 ,when1 in #ahed1 ,arago's place had to be filled at the head of the great ,paris ,observatory1 it was universally felt that the discoverer of ,neptune was the suitable man to assume the office4 ,leverrier died on ,sunday1 ,september #bc1 #ahgg1 in his sixty-seventh year4 99 99 99 99 99 ,,frederick ,,william ,,bessel was born at ,minden in #aghd1 and early turned his attention to mathematical subjects4 ,he devoted himself with ardor to astronomy1 and in #ahjd he undertook the reduction of the observations made on the comet of #afjg4 ,his results were communicated to ,olbers1 who warmly praised the young astronomer1 and in #ahjf recommended him to ,schroeter as an assistant in the observatory of ,lilienthal4 ,in #ahaj he was appointed director of the new observatory then being founded by the king at ,knigsberg4 ,he was admirably fitted for this post1 and is distinguished mainly for his discovery of the parallax of the star #fa ,cygni1 which he accomplished by methods of extreme ingenuity and delicacy4 ,two kinds of telescopes are commonly used1 the refractor and the reflector4 ,the first telescopes made were all refractors1 and the very first of them was made1 as you know1 by ,galileo4 ,the first reflector was made in later days by ,sir ,isaac ,newton4 ,in a refractor the rays of light1 from a star or any other bright body1 reach first a large object-glass1 through which they pass1 and by which1 as they pass1 they are caused to converge1 narrowing to a focus or point4 ,from this point they widen slightly on their way to the eye-piece4 ,after passing through the eye-piece1 by which they are once more straightened into parallel rays1 they arrive at the eye4 ,speaking broadly1 the eye receives--actually sees--nearly as much of the starlight as if its pupil were the full size of the object-glass of that telescope1 and the power of such an instrument depends upon the size of the object-glass4 ,a refractor has been made with an object-glass forty inches across1 and this1 for the observer1 means looking at a star with an eye pupil more than three feet in diameter4 ,this refractor is now in the ,yerkes ,observatory at ,williams ,bay1 ,lake ,geneva1 ,wisconsin4 ,there are several forms of reflectors4 ,with one form1 when it is pointed at a star1 the rays of starlight fall direct through the telescope-tube upon a highly-polished mirror1 so shaped that rays of light reflected thence are caused to fall converging upon a small plane-mirror in the center of the tube1 from which they are thrown1 parallel to the side of the tube1 to the eye-piece1 which converges them to the eye4 ,the mirror of a reflector can be made very much larger than the object-glass of a refractor4 ,the famous ,lord ,rosse telescope1 which has a tube sixty feet long1 contains a mirror no less than six feet in diameter4 ,this1 to an observer1 is tantamount to looking at the stars with an eye so huge that its pupil alone would be nearly equal in size to the six-foot wheel of a steam-engine4 ,it will readily be perceived how much more starlight can be grasped by such a fishing-net than by the tiny pupil of your eye or mine4 ,a main difference between the two kinds of telescope thus resides in the fact that the star-rays--or any other kind of light-rays--when first captured1 pass1 in one case1 through the glass on which they fall1 and1 in the other case1 are thrown off from the mirror4 ,in both cases1 the whole amount of light so captured is gathered into a small compass1 so as to be available for human sight4 ,illustration3 ,,eye-,,piece ,,of ,,the ,,lick ,,telescope4 ,once more1 let me remind you1 it should be always kept clearly in mind that every object that is seen by us--from a mote of dust to a sun1 from a coal-scuttle to a star--is perceived purely and solely by the light which it gives out1 either intrinsic or reflected light4 ,countless myriads of rays pass from the surface of the thing seen to our eyes1 picturing there1 on the sensitive retina1 a fleeting vision of its form4 ,all the leading ,governments in ,europe have observatories for the study of the heavens1 which are furnished with the best instruments of modern construction4 ,the principal observatories are those at ,paris1 ,berlin1 ,vienna1 ,nice2 ,dorpat1 the seat of a celebrated university founded by ,gustavus ,adolphus1 of ,sweden1 in #afcj2 ,pulkowa1 near ,st4 ,petersburg2 ,lisbon1 and at ,greenwich in ,england4 ,in ,america1 though only in recent years has astronomy been cultivated with ardor1 there are observatories of more or less importance1--the ,national ,observatory at ,washington1 ,d4 ,c42 the ,cincinnati ,observatory1 projected by the late ,general ,o4 ,m4 ,mitchel2 the ,dudley ,observatory1 founded by ,mrs4 ,blandina ,dudley in honor of her husband1 at ,albany1 ,n4 ,y42 the ,lick ,observatory1 founded by ,james ,lick1 on ,mount ,hamilton1 ,cal42 and the ,yerkes ,observatory1 connected with the ,chicago ,university1 founded by ,charles ,t4 ,yerkes4 ,besides these1 there are observatories connected with some of our other leading universities and colleges1 as those of ,harvard1 at ,cambridge1 ,mass42 ,yale ,university2 ,williams ,college2 ,west ,point ,military ,academy2 ,amherst ,college2 ,princeton2 ,dartmouth2 ,michigan ,university2 ,hamilton ,college1 ,n4 ,y41 and several others4 ,illustration3 ,,lick ,,observatory ,,in ,,winter1 ,,from ,,the ,,east4 ,the largest and best refracting telescopes in the world are those at ,lick ,observatory and at ,yerkes ,observatory1 now in charge of ,professor ,e4 ,e4 ,barnard1 who1 while at the head of the ,lick ,observatory1 discovered the fifth satellite of ,jupiter1 and determined the character of the inner ring of ,saturn4 ,the best reflecting telescope is that of ,lord ,rosse1 at ,birr ,castle1 in ,kings ,county1 ,ireland4 ,illustration3 ,e4 ,e4 ,,barnard4 ,in reviewing the path which we have traversed in this volume1 though we have penetrated the sidereal depths and wandered at will through space1 we feel that we have not yet reached the outskirts of creation4 ,we have never left the center4 ,beyond us still lies the circumference4 ,we see opened before us the infinite1 of which the study is not yet begun6 ,we have seen nothing2 we recoil in terror2 we fall back astounded4 ,indeed1 we might fall into the yawning abyss--fall forever1 during a whole eternity2 never1 never should we reach the bottom1 any more than we have attained the summit4 ,there is no east nor west1 neither right nor left4 ,there is no up nor down2 there is neither a zenith nor a nadir4 ,in whatever way we look1 it is infinite in all directions4 ,in this infinitude of space1 the associations of suns and of worlds which constitute our visible universe form but an island1 a vast archipelago2 and in the eternity of duration1 the life of our proud humanity1 with all its concerns1 its aspirations1 and its achievements1 the whole life of our entire planet1 is but the shadow of a dream6 ,well might the ,hebrew poet1 as he looked forth upon nature1 exclaim in his amazement3 8,when ,i consider thy heavens1 the work of thy fingers1 the moon and the stars which thou hast ordained1 what is man that thou art mindful of him1 and the son of man that thou visitest him80 ,the constellations1 the charts of the sky2 the catalogues of curious stars--variable1 double or multiple1 and colored2 the description of instruments accessible to the observer of the heavens1 and useful tables to consult1 are only touched upon in this volume4 ,the reader whose scientific desires are satisfied by the elements of astronomy1 may stop here4 ,few have time to pursue the subject further2 but it is sweet to live in the sphere of the mind2 it is sweet to contemn the rough noises of a vulgar world2 it is sweet to soar in the ethereal heights1 and to devote the best moments of our life to the study of the true1 the infinite1 and the eternal6 ,,publishers' ,,note4 ,we have now reached the conclusion of 8,the ,story of the ,sun1 ,moon1 and ,stars40 ,miss ,giberne's work has been supplemented with a large amount of matter from other sources4 ,the value of the book has thus been increased without diminishing its popular character4 ,in most admirable form it tells the story of the heavenly world1 which is the work of ,god's hands1 the moon and the stars which he has made4 ,the reverent reader1 to whom the ,word of ,god is 8sweeter than honey and the honey-comb10 may here find that 8the heavens declare the glory of ,god1 and the firmament showeth his handiwork40 ,we confidently present it to the reader as the best and completest work in print on the great subject of which it treats4 ,,index ,adams1 ,john ,couch1 #bca1 #bcf ,arolites1 #hd ,size of1 #hf ,aldebaran1 ,movement of1 #bgg ,alexander at ,arbela1 #adf ,alpha ,centauri1 ,distance of1 #ii ,duration of light journey1 #ajb ,position1 #bgi ,alps1 ,lunar ,mountains1 #agi ,altai1 ,lunar ,mountains1 #agi ,andromeda1 ,constellation of1 #aab ,apennines1 ,lunar ,mountains1 #agi ,arago1 #bce1 #djb ,arcturus1 ,motion of1 #aad ,position1 #bgf ,aristotle1 #cgf ,asteroids1 #ec ,astronomy1 ,the dawn of1 #cfc ,attraction1 #cd ,aurora ,borealis1 where seen1 #ada ,axis of earth slanting1 #dd ,barnard1 ,e4 ,e41 #ec1 #daj ,bessel1 ,f4 ,w41 #bhd ,discovery of star parallax1 #cbd ,discovers star parallax1 #dje ,bolides1 #hg1 #beg ,borelli1 #chh ,capella1 ,duration of light journey1 #ajc ,velocity of motion1 #aad ,caucasian ,range1 ,lunar ,mountains1 #agi ,carpathian1 ,lunar ,mountains1 #agi ,carrington1 #ada ,cassini1 ,measurement of sun's distance1 #caj ,cassiopeia1 ,constellation of1 #aab ,ceres1 size of1 #ec ,chaldean star-gazers1 #cfe ,chinese records of eclipses1 #cfe ,cicero1 #agg ,clark1 ,alvan ,graham1 #bhi ,cloven-disk theory1 #cca ,coal sack1 #cbi ,columbus in ,jamaica1 #adf ,comet1 ,biela's1 #ij1 #ic ,halley's1 #gh1 #bdh ,of #ahdc1 #hj ,newton's1 #gh ,with two tails1 #gg ,encke's1 #gh ,heat endured by1 #ha ,length of tail1 #ha ,collision with1 #hb ,split in two1 #ia ,comets1 #gc1 #bdj1 #bdf ,number of1 #ge ,nature of1 #gd ,captured by ,jupiter1 #bac ,composition of1 #bef ,composition of tails1 #bec ,orbits of1 #abi ,with closed orbits1 #gf ,confucius as an astronomer1 #cfe ,constellations1 ,grouping1 #cff ,when named1 #cff ,copernicus1 ,author of 8,celestial ,spheres10 #agg1 #ahc1 #cgj1 #cga1 #cge ,star parallax1 #cai ,copernican system of the universe1 #age ,corona1 ,description of1 #aec ,d',alembert1 #cii ,dante1 #aba ,demos1 ,satellite of ,mars1 #aia ,donati's ,comet1 #bdh1 #bej ,draco1 ,constellation of1 #aab ,earth1 ,globular1 #ag ,how formed1 #ba ,member of the ,solar ,system1 #ad ,in motion1 #af ,motions1 #ah1 #da1 #abf ,one of a family1 #ad ,size of1 #bf ,what is it8 #ac ,ecliptic1 #dc ,eclipses omens of evil1 #ade ,egyptian astronomers1 #cfe ,encke1 #bch ,epicycles1 #cgc ,equinox1 #dd ,fire-balls1 ,speed of1 #hh ,fabricius discovers sun-spots1 #bg ,fraunhofer1 ,joseph von1 #cde ,galle1 #bcb1 #bch ,galileo1 #bh1 #bgf1 #cga1 #cgf1 #cgh1 #chj ,gassendi1 #ahd ,george ,,iii1 #bbf ,gilbert1 #chh ,great ,bear1 ,constellation of1 #ajh1 #cdj ,halley1 #chh ,transit of ,venus1 #cad ,star motions1 #cah ,hercules1 ,constellation of1 #aab ,herschel1 ,caroline1 #bbf1 #cic ,herschel1 ,sir ,john1 #ha1 #bcc1 #cjc1 #cih ,herschel1 ,william1 #if1 #aai1 #bbe1 #bga1 #cic ,hipparchus1 #cfh1 #cga ,hodgson1 #ada ,holland1 ,sir ,henry1 #bcg ,hook1 ,robert1 #chh ,horrocks1 #chh ,huggins1 ,dr41 #cei ,humboldt1 ,alexander von1 #bfe ,jupiter1 #ee ,comparative size1 #ef ,distance of1 #abb ,his satellites1 #ef1 #bjf1 #baj ,velocity1 #aii ,wind storms1 #bjd ,kepler1 #ge1 #bif ,laws of1 #cga1 #cgd1 #chj1 #chh ,kew ,observatory1 #ada ,lacaille1 ,catalogue of1 #aje ,lalande1 ,catalogue of1 #aje ,laplace1 #che1 #cih ,later astronomy1 #cic ,leverrier1 ,urbain ,j4 ,j41 #bca1 #dja ,discovers ,neptune1 #cba ,light1 ,rapidity of1 #aja ,time1 ,duration of1 #cca ,lowe at ,santander1 #adg ,lunar craters1 ,antiquity of1 #agb ,how formed1 #agc ,plato and ,copernicus1 #agc ,ptolemy1 #agd ,schickard1 #agd ,tycho1 #agd ,lunar ,mountains1 ,how formed1 #agd ,lyra1 ,constellation1 #big ,magellanic clouds1 #cji ,magnetism1 #adj1 #ada ,mars1 #eb1 #cgc1 #cgd ,moons of1 #aia ,continents of1 #aig ,distance from earth1 #aig ,maury1 ,lieutenant1 #hj ,mercury1 ,atmosphere1 #aha ,distance from sun1 #di ,length of year1 #ahj ,is it inhabited8 #aha ,orbit of1 #ahj ,phases1 #ej ,size of1 #di ,transit of1 #ahd ,meteor1 #hd1 #beg ,meteorites1 #bdj1 #beg ,around the sun1 #id ,august system1 #ij1 #bdb ,in ,saturn's rings1 #id ,november system1 #ij1 #id1 #bda ,number of1 #hf ,protection from1 #hf ,shower of #ahgb1 #ib ,shower of #ahhe1 #ic ,milky ,way1 #bgj1 #cbi ,mizar1 #cdb ,modern ,astronomy1 #cge ,moon1 #fb ,appearance at its full1 #fc ,atmosphere1 #aeg1 #afi ,phases of1 #afj ,condition of1 #fe ,craters1 #fh1 #agj ,earth's satellite1 #afd ,earth-shine1 #afj ,eclipse1 #afc ,influence on tides1 #afg ,landscape of1 #fh ,mountains1 #fg ,orbit of1 #aff ,temperature on1 #gb ,revolution1 #fd ,size of1 #fd ,surface1 #fg ,nasmyth1 #agc ,nebul1 ,number of1 #ccf ,neptune1 #ei ,discovery of1 #bcb1 #bcd ,distance of1 #abc ,length of year1 #ei ,newton analyzes light1 #che ,birth and childhood1 #chb ,nicetos of ,syracuse1 #agg ,nicias1 ,athenian ,general1 #adf ,nicolas1 ,cardinal1 #agg ,observatories1 #djh ,orbits1 ,planetary1 #dg ,orion1 ,constellation of1 #aab ,parallax1 #caa ,phobos1 ,satellite of ,mars1 #aia ,photography1 ,stellar1 #cee ,pius ,,ix1 #ic ,pisa1 ,leaning ,tower of1 #cgh ,plane of the ,ecliptic1 #bja ,planets1 ,distance from the sun1 #abc ,first group1 #dh ,how formed1 #bb ,length of years1 #di ,orbits1 #dg ,order of formation1 #bc ,second group1 #dh1ee ,plutarch1 #agg ,pole star1 ,duration of light journey1 #ajc ,position1 #ajh ,rate of motion1 #aae ,prism1 #cdd ,pritchard1 ,c41 #cef ,ptolemaic system of the universe1 #age1 #cfi ,ptolemy1 #cga1 #cfi ,pythagoras1 ,grecian astronomer1 #cfg ,rosse1 ,lord1 ,telescope1 #djf ,rowton siderite1 #beh ,saturn1 #eg ,composition of rings1 #bba ,distance of1 #abb ,distance from sun1 #bad ,length of year1 #eg ,moons1 #bag ,rings1 #bai ,satellites1 #eh ,size1 #bad ,weight1 #bad ,shickard1 ,crater on the moon1 #agd ,scheiner1 #bh ,secchi1 #ib ,shooting stars1 #hd ,sirius1 ,brightness of1 #bge1 #bhe ,changing color1 #bhe ,distance of1 #ajj ,duration of light journey1 #ajc ,movement of1 #bgg ,solar cloud1 #adh ,solar ,system1 #fj1 #abb ,model of1 #fj ,spectroscope1 #adc1 #cde ,spectroscopic photography1 #cfj ,spectrum analysis1 #cdf1 #ced ,star clusters1 #cjd1 #ccf ,parallax1 #bhd1 #caf ,spectroscopy1 #cef ,stars1 ,apparent motion1 #ajg ,attraction1 #ba ,distance of1 #ii1 #caj1 #cbj ,distance1 #bha1 #bhb ,fixed1 ,why so called1 #bj ,fixed1 ,why1 #cff ,golden1 #bgd ,magnitude of1 #ig ,how many visible1 #ie ,measurement1 #bgh ,red1 #bgd ,variable1 #bgd1 #bia ,white1 #bgd ,sun1 #bd ,attraction of1 #aef ,attraction of gravitation1 #cd ,chromatosphere1 #cb ,cyclones of #cj1 #acf ,density1 #bf ,destination1 #aai ,distance of1 #be ,eclipse of1 #adc ,flames1 ,their height1 #ca1 #aea ,flames1 ,their velocity1 #ach ,forces and influences1 #ci ,head of our family1 #bd ,magnetic power of1 #aci ,its mottled appearance1 #adb ,rate of motion1 #aai ,penumbra1 #acc ,photosphere1 #ca1 #acd ,power of1 #ci1 #acg ,rapidity of motion1 #bf ,revolution on axis1 #bh ,size1 #bf1 #aed ,solar prominence1 #cb ,spots1 #bg1 #cj1 #acc ,symbol of purity1 #chj ,umbra1 #acc ,weight1 #bg1 #aed ,swift1 ,voyage to ,laputa1 #aid ,telescopes1 #cgh1 #cgi1 #dje ,refractors and reflectors1 #dje1 #djh1 #daj ,tides1 #afh ,thales1 founder of ,grecian ,astronomy1 #cfg ,toucan1 #cjf ,tycho ,brahe1 #age1 #cga1 #cgb1 #cgc ,universe1 ,definition of1 #ai ,uranus1 #eh ,discovery of1 #bbe ,distance of1 #abc ,venus1 ,orbit of #ea ,is it inhabited8 #ahi ,distance from earth1 #ahf ,phases of1 #ea1 #cgi ,transits of1 #ahe ,vesta1 ,size of1 #ec ,voltaire1 ,prophecy of1 #aic ,wilson1 #cj ,wollaston1 ,dr4 ,w4 ,h41 #cde ,wren1 #chh ,yerkes ,observatory1 #djf ,young1 ,chas4 ,a41 #adb1 #adh ,zodiacal ,light1 #id1 #bbd1 #bfe ,transcriber's ,notes3 ,in the original a link to ,sir ,isaac ,newton was omitted from the ,list of ,illustrations4 ,the transcriber has inserted one4 ,italics are shown thus3 sloping4 ,variations in spelling and hyphenation are retained4 ,perceived typographical errors have been changed4