,,the ,,new ,,astronomy ,,the ,,new ,,astronomy ,,by ,,samuel ,,pierpont ,,langley1 ,,ph4,d41 ,,ll4,d4 ,,director ,,of ,,the ,,allegheny ,,observatory1 ,,member ,,national ,,academy1 ,,fellow ,,royal ,,astronomical ,,society1 ,,etc41 ,,etc4 ,illustrated ,illustration ,,boston4 ,,ticknor ,,and ,,company #baa ,tremont ,street #ahhh ,,copyright1 #ahhd1 #ahhe1 #ahhf1 ,,and #ahhg1 ,,by ,,the ,,century ,,co42 ,,and #ahhg1 ,,by ,s4 ,p4 ,,langley4 ,all rights reserved4 ,university ,press3 ,,john ,,wilson ,,and ,,son1 ,,cambridge4 ,,preface4 ,i have written these pages1 not for the professional reader1 but with the hope of reaching a part of that educated public on whose support he is so often dependent for the means of extending the boundaries of knowledge4 ,it is not generally understood that among us not only the support of the ,government1 but with scarcely an exception every new private benefaction1 is devoted to 8the ,old0 ,astronomy1 which is relatively munificently endowed already2 while that which ,i have here called 8the ,new10 so fruitful in results of interest and importance1 struggles almost unaided4 ,we are all glad to know that ,urania1 who was in the beginning but a poor ,chaldean shepherdess1 has long since become well-to-do1 and dwells now in state4 ,it is far less known than it should be that she has a younger sister now among us1 bearing every mark of her celestial birth1 but all unendowed and portionless4 ,it is for the reader's interest in the latter that this book is a plea4 ,,contents4 ,,chapter ,,page ,i4 ,,spots ,,on ,,the ,,sun #a ,,ii4 ,,the ,,sun',s ,,surroundings #ce ,,iii4 ,,the ,,sun',s ,,energy #gj ,,iv4 ,,the ,,sun',s ,,energy 7,continued7 #ia ,v4 ,,the ,,planets ,,and ,,the ,,moon #aag ,,vi4 ,,meteors #age ,,vii4 ,,comets #aii ,,viii4 ,,the ,,stars #bba ,,index #bec ,,list ,,of ,,illustrations4 ,,figure ,,page #a4 ,,the ,,sun',s ,,surroundings #d #b4 ,,view ,,of ,,the ,,sun ,,on ,,sept4 #bj1 #ahgj #f #c4 ,,the ,,sun ,,on ,,sept4 #bb1 #ahgj #f #d4 ,,the ,,sun ,,on ,,sept4 #bf1 #ahgj #g #e4 ,,the ,,sun ,,on ,,sept4 #ai1 #ahgj #h #f4 ,,the ,,sun ,,on ,,sept4 #bj1 #ahgj #h #g4 ,,the ,,sun ,,on ,,sept4 #ba1 #ahgj #i #h4 ,,the ,,sun ,,on ,,sept4 #bb1 #ahgj #i #i4 ,,the ,,sun ,,on ,,sept4 #bc1 #ahgj #aj #aj4 ,,the ,,sun ,,on ,,sept4 #bf1 #ahgj #aj #aa4 ,,nasmyth',s ,,willow ,,leaves #aa #ab4 ,,the ,,cactus ,,type #ab #ac4 ,,equatorial ,,telescope ,,and ,,projection #ac #ad4 ,,polarizing ,,eye-,,piece #ad #ae4 ,,spot ,,of ,,sept4 #ba1 #ahgj #ae #af4 ,,spot ,,of ,,march #e1 #ahgc #ae #ag4 ,,sun ,,on ,,march #e1 #ahgc #ah #ah4 8,,the ,,plume0 ,,spot ,,of ,,march #e ,,and #f1 #ahgc #ai #ai4 ,,typical ,,sun-,,spot ,,of ,,december1 #ahgc #ba #bj4 ,,frost ,,crystal #bc #ba4 ,,cyclone ,,spot #bd #bb4 ,,spot ,,of ,,march #ca1 #ahge #be #bc4 ,,cirrous ,,cloud #bg #bd4 ,,spot ,,of ,,march #ca1 #ahge #bh #be4 ,,typical ,,illustration ,,of ,,faye',s ,,theory #bi #bf4 ,,spot ,,of ,,oct4 #ac1 #ahgf #cj #bg4 ,,photograph ,,of ,,edge ,,of ,,sun #ca #bh4 ,,facula #cc #bi4 ,,lunar ,,cone ,,shadow #cf #cj4 ,,track ,,of ,,lunar ,,shadow #ci #ca4 ,,inner ,,corona ,,eclipse ,,of #ahfi #dj #cb4 ,,sketch ,,of ,,outer ,,corona1 #ahfi #da #cc4 ,,tacchini',s ,,drawing ,,of ,,corona ,,of #ahgj #dc #cd4 ,,watson',s ,,naked-,,eye ,,drawing ,,of ,,corona ,,of #ahgj #dd #ce4 ,,photograph ,,showing ,,commencement ,,of ,,outer ,,corona #de #cf4 ,,eclipse ,,of #aheg1 ,,drawing ,,by ,,liais #dh #cg4 ,,enlargement ,,of ,,part ,,of ,,fig4 #ch #di #ch4 ,,fac-,,simile ,,of ,,photograph ,,of ,,corona ,,of #ahga #ea #ci4 8,,spectres0 #ed #dj4 ,,outer ,,corona ,,of #ahgh #eg #da4 ,,spectroscope ,,slit ,,and ,,solar ,,image #ei #db4 ,,slit ,,and ,,prominences #ei #dc4 ,,tacchini',s ,,chromospheric ,,clouds #fb #dd4 ,,tacchini',s ,,chromospheric ,,clouds #fb #de4 ,,vogel',s ,,chromospheric ,,forms #fd #df4 ,,tacchini',s ,,chromospheric ,,forms #ff #dg4 ,,eruptive ,,prominences #fg #dh4 ,,sun-,,spots ,,and ,,price ,,of ,,grain #gg #di4 ,,sun-,,spot ,,of ,,nov4 #af1 #ahhb1 ,,and ,,earth #hj #ej4 ,,greenwich ,,record ,,of ,,disturbance ,,of ,,magnetic ,,needle1 ,,nov4 #af ,,and #ag1 #ahhb #ha #ea4 ,,sun-,,spots ,,and ,,magnetic ,,variations #hg #eb4 ,,greenwich ,,magnetic ,,observations1 ,,aug4 #c ,,and #e1 #ahgb #hi #ec4 ,,one ,,cubic ,,centimetre #ic #ed4 ,,pouillet',s ,,pyrheliometer #ic #ee4 ,,berni,,res',s ,,great ,,burning-,,glass #ajc #ef4 ,a 8,,pour0 ,,from ,,the ,,bessemer ,,converter #aje #eg4 ,,photometer-,,box #ajh #eh4 ,,mouchot',s ,,solar ,,engine #aji #ei4 ,,ericsson',s ,,new ,,solar ,,engine1 ,,now ,,in ,,practical ,,use ,,in ,,new ,,york #aac #fj4 ,,saturn #aai #fa4 ,,the ,,equatorial ,,telescope ,,at ,,washington #abb #fb4 ,,jupiter1 ,,moon1 ,,and ,,shadow #abe #fc4 ,,three ,,views ,,of ,,mars #abi #fd4 ,,map ,,of ,,mars #abi #fe4 ,,the ,,moon #acg #ff4 ,,the ,,full ,,moon #ada #fg4 ,,glass ,,globe1 ,,cracked #ade #fh4 ,,plato ,,and ,,the ,,lunar ,,alps #adi #fi4 ,,the ,,lunar ,,apennines3 ,,archimedes #aec #gj4 ,,vesuvius ,,and ,,neighborhood ,,of ,,naples #aeg #ga4 ,,ptolemy ,,and ,,arzachel #afa #gb4 ,,mercator ,,and ,,campanus #afe #gc4 ,,withered ,,hand #afh #gd4 ,,ideal ,,lunar ,,landscape ,,and ,,earth-,,shine #afi #ge4 ,,withered ,,apple #aga #gf4 ,,gassendi4 ,,nov4 #g1 #ahfg #agc #gg4 ,,the ,,camp ,,at ,,mount ,,whitney #agg #gh4 ,,vesuvius ,,during ,,an ,,eruption #ahc #gi4 ,,meteors ,,observed ,,nov4 #ac ,,and #ad1 #ahfh1 ,,between ,,midnight ,,and ,,five ,o',,clock1 ,a4 ,m4 #ahi #hj4 ,,comet ,,of ,,donati1 ,,sept4 #af1 #aheh #bja #ha4 8,a ,,part ,,of ,a ,,comet0 #bjc #hb4 ,,comet ,,of ,,donati1 ,,sept4 #bd1 #aheh #bje #hc4 ,,comet ,,of ,,donati1 ,,oct4 #c1 #aheh #bji #hd4 ,,comet ,,of ,,donati1 ,,oct4 #i1 #aheh #bac #he4 ,,comet ,,of ,,donati1 ,,oct4 #e1 #aheh #bag #hf4 ,,types ,,of ,,stellar ,,spectra #bbb #hg4 ,,the ,,milky ,,way #bbe #hh4 ,,spectra ,,of ,,stars ,,in ,,pleiades #bca #hi4 ,,spectrum ,,of ,,aldebaran #bce #ij4 ,,spectrum ,,of ,,vega #bce #ia4 ,,great ,,nebula ,,in ,,orion #bci #ib4 ,a ,,falling ,,man #bdc #ic4 ,a ,,flash ,,of ,,lightning #bde ,,the ,,new ,,astronomy4 ,i4 ,,spots ,,on ,,the ,,sun4 ,the visitor to ,salisbury ,plain sees around him a lonely waste1 utterly barren except for a few recently planted trees1 and otherwise as desolate as it could have been when ,hengist and ,horsa landed in ,britain2 for its monotony is still unbroken except by the funeral mounds of ancient chiefs1 which dot it to its horizon1 and contrast strangely with the crowded life and fertile soil which everywhere surround its borders4 ,in the midst of this loneliness rise the rude1 enormous monoliths of ,stonehenge1--circles of gray stones1 which seem as old as time1 and were there1 as we now are told1 the temple of a people which had already passed away1 and whose worship was forgotten1 when our ,saxon forefathers first saw the place4 ,in the centre of the inner circle is a stone which is believed once to have been the altar2 while beyond the outmost ring1 quite away to the northeast upon the open plain1 still stands a solitary stone1 set up there evidently with some special object by the same unknown builders4 ,seen under ordinary circumstances1 it is difficult to divine its connection with the others2 but we are told that once in each year1 upon the morning of the longest day1 the level shadow of this distant1 isolated stone is projected at sunrise to the very centre of the ancient sanctuary1 and falls just upon the altar4 ,the primitive man who devised this was both astronomer and priest1 for he not only adored the risen god whose first beams brought him light and warmth1 but he could mark its place1 and though utterly ignorant of its nature1 had evidently learned enough of its motions to embody his simple astronomical knowledge in a record so exact and so enduring that though his very memory has gone1 common men are still interested in it2 for1 as ,i learned when viewing the scene1 people are accustomed to come from all the surrounding country1 and pass in this desolate spot the short night preceding the longest day of the year1 to see the shadow touch the altar at the moment of sunrise4 ,most great national observatories1 like ,greenwich or ,washington1 are the perfected development of that kind of astronomy of which the builders of ,stonehenge represent the infancy4 ,those primitive men could know where the sun would rise on a certain day1 and make their observation of its place1 as we see1 very well1 without knowing anything of its physical nature4 ,at ,greenwich the moon has been observed with scarcely an intermission for one hundred and fifty years1 but we should mistake greatly did we suppose that it was for the purpose of seeing what it was made of1 or of making discoveries in it4 ,this immense mass of ,greenwich observations is for quite another purpose1--for the very practical purpose of forming the lunar tables1 which1 by means of the moon's place among the stars1 will tell the navigator in distant oceans where he is1 and conduct the fleets of ,england safely home4 ,in the observatory at ,washington one may see a wonderfully exact instrument1 in which circles of brass have replaced circles of stone1 all so bolted between massive piers that the sun can be observed by it but once daily1 as it crosses the meridian4 ,this instrument is the completed attainment along that long line of progress in one direction1 of which the solitary stone at ,stonehenge marks the initial step1--the attainment1 that is1 purely of precision of measurement2 for the astronomer of to-day can still use his circles for the special purpose of fixing the sun's place in the heavens1 without any more knowledge of that body's chemical constitution than had the man who built ,stonehenge4 ,yet the object of both is1 in fact1 the same4 ,it is true that the functions of astronomer and priest have become divided in the advance of our modern civilization1 which has committed the special cultivation of the religious aspect of these problems to a distinct profession2 while the modern observer has possibly exchanged the emotions of awe and wonder for a more exact knowledge of the equinox than was possessed by his primitive brother1 who both observed and adored4 ,still1 both aim at the common end1 not of learning what the sun is made of1 but of where it will be at a certain moment2 for the prime object of astronomy1 until very lately indeed1 has still been to say where any heavenly body is1 and not what it is4 ,it is this precision of measurement1 then1 which has always--and justly--been a paramount object of this oldest of the sciences1 not only as a good in itself1 but as leading to great ends2 and it is this which the poet of ,urania has chosen rightly to note as its characteristic1 when he says1-- 8,that little ,vernier1 on whose slender lines ,the midnight taper trembles as it shines1 ,tells through the mist where dazzled ,mercury burns1 ,and marks the point where ,uranus returns40 ,but within a comparatively few years a new branch of astronomy has arisen1 which studies sun1 moon1 and stars for what they are in themselves1 and in relation to ourselves4 ,its study of the sun1 beginning with its external features 7and full of novelty and interest1 even1 as regards those71 led to the further inquiry as to what it was made of1 and then to finding the unexpected relations which it bore to the earth and our own daily lives on it1 the conclusion being that1 in a physical sense1 it made us and re-creates us1 as it were1 daily1 and that the knowledge of the intimate ties which unite man with it brings results of the most practical and important kind1 which a generation ago were unguessed at4 ,this new branch of inquiry is sometimes called ,celestial ,physics1 sometimes ,solar ,physics1 and is sometimes more rarely referred to as the ,new ,astronomy4 ,i will call it here by this title1 and try to tell the reader something about it which may interest him1 beginning with the sun4 ,illustration3 ,,fig4 #a4--,,the ,,sun',s ,,surroundings4 ,the whole of what we have to say about the sun and stars presupposes a knowledge of their size and distance1 and we may take it for granted that the reader has at some time or another heard such statements as that the moon's distance is two hundred and forty thousand miles1 and the sun's ninety-three million 7and very probably has forgotten them again as of no practical concern74 ,he will not be offered here the kind of statistics which he would expect in a college text-book2 but we must linger a moment on the threshold of our subject--the nature of these bodies--to insist on the real meaning of such figures as those just quoted4 ,we are accustomed to look on the sun and moon as far off together in the sky2 and though we know the sun is greater1 we are apt to think of them vaguely as things of a common order of largeness1 away among the stars4 ,it would be safe to say that though nine out of ten readers have learned that the sun is larger than the moon1 and1 in fact1 larger than the earth itself1 most of them do not at all realize that the difference is so enormous that if we could hollow out the sun's globe and place the earth in the centre1 there would still be so much room that the moon might go on moving in her present orbit at two hundred and forty thousand miles from the earth1--all within the globe of the sun itself1--and have plenty of room to spare4 ,as to the distance of ninety-three million miles1 a cannon-ball would travel it in about fifteen years4 ,it may help us to remember that at the speed attained by the ,limited ,express on our railroads a train which had left the sun for the earth when the 8,mayflower0 sailed from ,delftshaven with the ,pilgrim ,fathers1 and which ran at that rate day and night1 would in #ahhg still be a journey of some years away from its terrestrial station4 ,the fare at the customary rates1 it may be remarked1 would be rather over two million five hundred thousand dollars1 so that it is clear that we should need both money and leisure for the journey4 ,perhaps the most striking illustration of the sun's distance is given by expressing it in terms of what the physiologists would call velocity of nerve transmission4 ,it has been found that sensation is not absolutely instantaneous1 but that it occupies a very minute time in travelling along the nerves2 so that if a child puts its finger into the candle1 there is a certain almost inconceivably small space of time1 say the one-hundredth of a second1 before he feels the heat4 ,in case1 then1 a child's arm were long enough to touch the sun1 it can be calculated from this known rate of transmission that the infant would have to live to be a man of over a hundred before it knew that its fingers were burned4 ,trying with the help of these still inadequate images1 we may get some idea of the real size and distance of the sun4 ,i could wish not to have to dwell upon such figures1 that seem1 however1 indispensable2 but we are now done with these1 and are ready to turn to the telescope and see what the sun itself looks like4 ,illustration3 ,,fig4 #b4--,,view ,,of ,,the ,,sun ,,on ,,sept4 #bj1 #ahgj4 ,illustration3 ,,fig4 #c4--,,the ,,sun ,,on ,,sept4 #bb1 #ahgj4 7,,from ,a ,,photograph7 ,the sun1 as we shall learn later1 is a star1 and not a particularly large star4 ,it is1 as has been said1 8only a private in the host of heaven10 but it is one of that host2 it is one of those glittering points to which we have been brought near4 ,let us keep in mind1 then1 from the first1 what we shall see confirmed later1 that there is an essentially similar constitution in them all1 and not forget that when we study the sun1 as we now begin to do1 we are studying the stars also4 ,if we were called on to give a description of the earth and all that is on it1 it would be easily understood that the task was impossibly great1 and that even an account of its most striking general features might fill volumes4 ,so it is with the sun2 and we shall find that in the description of the general character of its immediate surface alone1 there is a great deal to be told4 ,first1 let us look at a little conventional representation 7,fig4 #a71 as at a kind of outline of the unknown regions we are about to explore4 ,the circle represents the ,photosphere1 which is simply what the word implies1 that 8sphere0 of 8light0 which we have daily before our eyes1 or which we can study with the telescope4 ,outside this there is a thin envelope1 which rises here and there into irregular prominences1 some orange-scarlet1 some rose-pink4 ,this is the ,chromosphere1 a thin shell1 mainly of crimson and scarlet tints1 invisible even to the telescope except at the time of a total eclipse1 when alone its true colors are discernible1 but seen as to its form at all times by the spectroscope4 ,it is always there1 not hidden in any way1 and yet not seen1 only because it is overpowered by the intenser brilliancy of the ,photosphere1 as a glow-worm's shine would be if it were put beside an electric light4 ,outside all is the strange shape1 which represents the mysterious ,corona1 seen by the naked eye in a total eclipse1 but at all other times invisible even to telescope and spectroscope1 and of whose true nature we are nearly ignorant from lack of opportunity to study it4 ,illustration3 ,,fig4 #d4--,,the ,,sun ,,on ,,sept4 #bf1 #ahgj4 ,disregarding other details1 let us carry in our minds the three main divisions1--the ,photosphere1 or daily visible surface of the sun1 which contains nearly all its mass or substance2 the ,chromosphere2 and the unsubstantial ,corona1 which is nevertheless larger than all the rest4 ,we begin our examination with the ,photosphere4 ,there are records of spots having been seen with the naked eye before the invention of the telescope1 but they were supposed to be planets passing between us and the surface2 and the idea that the sun was pure fire1 necessarily immaculate1 was taught by the professors of the ,aristotelian philosophy in medival schools1 and regarded almost as an article of religious faith4 ,we can hardly conceive1 now1 the shock of the first announcement that spots were to be found on the sun1 but the notion partook in contemporary minds at once of the absurd and the impious2 and we notice here1 what we shall have occasion to notice again1 that these physical discoveries from the first affect men's thoughts in unexpected ways1 and modify their scheme of the moral universe as well as of the physical one4 ,illustration3 ,,fig4 #e4--,,sept4 #ai1 #ahgj4 ,illustration3 ,,fig4 #f4--,,sept4 #bj1 #ahgj4 7,,engraved ,,from ,a ,,photograph ,,by ,,rutherfurd47 ,very little indeed was added to the early observations of ,fabricius and ,galileo until a time within the remembrance of many of us2 for it is since the advent of the generation now on the stage that nine-tenths of the knowledge of the subject has been reached4 ,let us first take a general view of the sun1 and afterward study it in detail4 ,what we see with a good telescope in this general view is something like this4 ,opposite are three successive views 7,figs4 #b1 #c1 #d7 taken on three successive days1--quite authentic portraits1 since the sun himself made them2 they being1 in fact1 projected telescopic images which have been fixed for us by photography1 and then exactly reproduced by the engraver4 ,the first was taken 7by ,mr4 ,rutherfurd1 of ,new ,york7 on the #bjth of ,september1 #ahgj1 when a remarkably large spot had come into view4 ,it is seen here not far from the eastern edge 7the left hand in the engraving71 and numerous other spots are also visible4 ,the reader should notice the position of these1 and then on turning to the next view 7,fig4 #c1 taken on ,september #bb;d7 he will see that they have all shifted their places1 by a common motion toward the west4 ,the great spot on the left has now got well into view1 and we can see its separate parts2 the group which was on the left of the centre has got a little to the right of it1 and so on4 ,from the common motion of them all1 we might suspect that the sun was turning round on an axis like the earth1 carrying the spots with it2 and as we continue to observe1 this suspicion becomes certainty4 ,in the third view 7,fig4 #d71 taken on ,september #bfth1 the spot we first saw on the left has travelled more than half across the disk1 while others we saw on ,september #bjth have approached to the right-hand edge or passed wholly out of sight behind it4 ,the sun does rotate1 then1 but in twenty-five or twenty-six of our days1--,i say twenty-five or twenty-six1 because 7what is very extraordinary7 it does not turn all-of-a-piece like the earth1 but some parts revolve faster than others1--not only faster in feet and inches1 but in the number of turns1--just as though the rim of a carriage wheel were to make more revolutions in a mile than the spokes1 and the spokes more than the hub4 ,of course no solid wheel could so turn without wrenching itself in pieces1 but that the great solar wheel does1 is incontestable2 and this alone is a convincing proof that the sun's surface is not solid1 but liquid or gaseous4 ,illustration3 ,,fig4 #g4--,,sept4 #ba1 #ahgj4 ,illustration3 ,,fig4 #h4--,,sept4 #bb1 #ahgj4 ,but let us return to the great spot which we saw coming round the eastern edge4 ,possibly the word 8great0 may seem misapplied to what was but the size of a pin-head in the first engraving1 but we must remember that the disk of the sun there shown is in reality over #hjj1jjj miles in diameter4 ,we shall soon see whether this spot deserves to be called 8great0 or not4 ,illustration3 ,,fig4 #i4--,,sept4 #bc1 #ahgj4 ,illustration3 ,,fig4 #aj4--,,sept4 #bf1 #ahgj4 ,next we have six enlarged views of it on the #aith1 #bjth1 #bast1 #bb;d1 #bc;d1 and #bfth4 ,on the #aith it is seen very near the eastern limb1 showing like a great hole in the sun1 and foreshortened as it comes into view around the dark edge2 for the edge of the sun is really darker than the central parts1 as it is shown here1 or as one may see even through a smoked glass by careful attention4 ,on the #bjth we have the edge still visible1 but on the #bast the spot has advanced so far that the edge cannot be shown for want of room4 ,we see distinctly the division of the spot into the outer shades which constitute the penumbra1 and the inner darker ones which form the umbra and nucleus4 ,we notice particularly in this enlarged view1 by comparing the appearances on the #bast1 #bb;d1 and #bc;d1 that the spot not only turns with the sun 7as we have already learned71 but moves and changes within itself in the most surprising way1 like a terrestrial cloud1 which not only revolves with the rest of the globe1 but varies its shape from hour to hour4 ,this is seen still more plainly when we compare the appearance on the #bc;d with that on the #bfth1 only three days later1 where the process has begun by which the spot finally breaks up and forever disappears4 ,on looking at all this1 the tremendous scale on which the action occurs must be borne in mind4 ,on the #bast1 for instance1 the umbra1 or dark central hole1 alone was large enough to let the whole globe of our own earth drop in without touching the sides6 ,we shall have occasion to recur to this view of the #bast ,september again4 ,illustration3 ,,fig4 #aa4--,,nasmyth',s ,,willow ,,leaves4 7,,from ,,herschel',s 8,,outlines ,,of ,,astronomy407 ,in looking at this spot and its striking changes1 the reader must not omit to notice1 also1 a much less obvious feature1--the vaguely seen mottlings which show all over the sun's surface1 both quite away from the spots and also close to them1 and which seem to merge into them4 ,illustration3 ,,fig4 #ab4--,,the ,,cactus ,,type4 7,,from ,,secchi',s 8,,le ,,soleil407 ,i think if we assign one year rather than another for the birth of the youthful science of solar physics1 it should be #ahfa1 when ,kirchhoff and ,bunsen published their memorable research on ,spectrum ,analysis1 and when ,nasmyth observed what he called the 8willow-leaf0 structure of the solar surface 7see ,fig4 #aa74 ,mr4 ,nasmyth1 with a very powerful reflecting telescope1 thought he had succeeded in finding what these faint mottlings really are composed of1 and believed that he had discovered in them some most extraordinary things4 ,this is what he thought he saw3 ,the whole sun is1 according to him1 covered with huge bodies of most definite shape1 that of the oblong willow leaf1 and of enormous but uniform size2 and the faint mottlings the reader has just noticed are1 according to him1 made up of these4 8,these10 he says1 8cover the whole disk of the sun 7except in the space occupied by the spots7 in countless millions1 and lie crossing each other in every imaginable direction40 ,sir ,john ,herschel took a particular interest in the supposed discovery1 and1 treating it as a matter of established fact1 proceeded to make one of the most amazing suggestions in explanation that ever came from a scientific man of deserved eminence4 ,we must remember how much there is unknown in the sun still1 and what a great mystery even yet overhangs many of our relations to that body which maintains our own vital action1 when we read the following words1 which are ,herschel's own4 ,speaking of these supposed spindle-shaped monsters1 he says3 8,the exceedingly definite shape of these objects1 their exact similarity to one another1 and the way in which they lie across and athwart each other1--all these characters seem quite repugnant to the notion of their being of a vaporous1 a cloudy1 or a fluid nature4 ,nothing remains but to consider them as separate and independent sheets1 flakes1 or scales1 having some sort of solidity4 ,and these 444 are evidently the immediate sources of the solar light and heat1 by whatever mechanism or whatever processes they may be enabled to develop1 and as it were elaborate1 these elements from the bosom of the non-luminous fluid in which they appear to float4 ,looked at in this point of view1 we cannot refuse to regard them as organisms of some peculiar and amazing kind2 and though it would be too daring to speak of such organization as partaking of the nature of life1 yet we do know that vital action is competent to develop at once heat and light and electricity40 ,illustration3 ,,fig4 #ac4--;,,equatorial ,,telescope ,,and ,,projection4 ,such are his words2 and when we consider that each of these solar inhabitants was supposed to extend about two hundred by one thousand miles upon the surface of the fiery ocean1 we may subscribe to ,mr4 ,proctor's comment1 that 8,milton's picture of him who on the fires of hell #8lay floating many a rood1' seems tame and commonplace compared with ,herschel's conception of these floating monsters1 the least covering a greater space than the ,british ,islands40 ,illustration3 ,,fig4 #ad4--,,polarizing ,,eye-,,piece4 ,i hope ,i may not appear wanting in respect for ,sir ,john ,herschel--a man whose memory ,i reverence--in thus citing views which1 if his honored life could have been prolonged1 he would have abandoned4 ,i do so because nothing else can so forcibly illustrate the field for wonder and wild conjecture solar physics presented even a few years ago2 and its supposed connection with that 8,vital ,force10 which was till so lately accepted by physiology1 serves as a kind of landmark on the way we have come4 ,this new science of ours1 then1 youthful as it is1 has already had its age of fable4 ,after a time ,nasmyth's observation was attributed to imperfect definition1 but was not fairly disproved4 ,he had1 indeed1 a basis of fact for his statement1 and to him belongs the credit of first pointing out the existence of this minute structure1 though he mistook its true character4 ,it will be seen later how the real forms might be mistaken for leaves1 and in certain particular cases they certainly do take on a very leaf-like appearance4 ,here is a drawing 7,fig4 #ab7 which ,father ,secchi gives of some of them in the spot of ,april #ad1 #ahfg1 and which he compares to a branch of cactus4 ,he remarks somewhere else that they resemble a crystallization of sal-ammoniac1 and calls them veils of most intricate structure4 ,this was the state of our knowledge in #ahgj1 and it may seem surprising that such wonderful statements had not been proved or disproved1 when they referred to mere matters of observation4 ,but direct observation is here very difficult on account of the incessant tremor and vibration of our own atmosphere4 ,illustration3 ,,fig4 #ae4--,,spot ,,of ,,sept4 #ba1 #ahgj4 7,,reduced ,,from ,,an ,,original ,,drawing ,,by ,s4 ,p4 ,,langley47 ,illustration3 ,,fig4 #af4--,,spot ,,of ,,march #e1 #ahgc4 7,,reduced ,,from ,,an ,,original ,,drawing ,,by ,s4 ,p4 ,,langley47 ,the surface of the sun may be compared to an elaborate engraving1 filled with the closest and most delicate lines and hatchings1 but an engraving which during ninety-nine hundredths of the time can only be seen across such a quivering mass of heated air as makes everything confused and liable to be mistaken1 causing what is definite to look like a vaguely seen mottling4 ,it is literally true that the more delicate features we are about to show1 are only distinctly visible even by the best telescope during less than one-hundredth of the time1 coming out as they do in brief instants when our dancing air is momentarily still1 so that one who has sat at a powerful telescope all day is exceptionally lucky if he has secured enough glimpses of the true structure to aggregate five minutes of clear seeing1 while at all other times the attempt to magnify only produces a blurring of the image4 ,this study1 then1 demands not only fine telescopes and special optical aids1 but endless patience4 ,illustration3 ,,fig4 #ag4--,,sun ,,on ,,march #e1 #ahgc4 7,,from ,a ,,drawing ,,by ,s4 ,p4 ,,langley47 ,my attention was first particularly directed to the subject in #ahgj 7shortly after the regular study of the ,photosphere was begun at the ,allegheny ,observatory by means of its equatorial telescope of thirteen inches' aperture71 with the view of finding out what this vaguely seen structure really is4 ,nearly three years of constant watching were given to obtain the results which follow4 ,the method ,i have used for it is indicated in the drawing 7,fig4 #ac71 which shows the preliminary step of projecting the image of the sun directly upon a sheet of paper1 divided into squares and attached to the eye-end of a great equatorial telescope4 ,when this is directed to the sun in a darkened dome1 the solar picture is formed upon the paper as in a camera obscura1 and this picture can be made as large or as small as we please by varying the lenses which project it4 ,as the sun moves along in the sky1 its image moves across the paper2 and as we can observe how long the whole sun 7whose diameter in miles is known7 takes to cross1 we can find how many miles correspond to the time it is in crossing one of the squares1 and so get the scale of the future drawing1 and the true size in miles of the spot we are about to study4 ,then a piece of clock-work attached to the telescope is put in motion1 and it begins to follow the sun in the sky1 and the spot appears fixed on the paper4 ,a tracing of the spot's outline is next made1 but the finer details are not to be observed by this method1 which is purely preliminary1 and only for the purpose of fixing the scale and the points of the compass 7so to speak7 on the sun's face4 ,the projecting apparatus is next removed and replaced by the polarizing eye-piece4 ,sir ,william ,herschel used to avoid the blinding effects of the concentrated solar light by passing the rays through ink and water1 but the phenomena of 8polarization0 have been used to better advantage in modern apparatus4 ,this instrument1 one of the first of its kind ever constructed1 and in which the light is polarized with three successive reflections through the three tubes seen in the drawing 7,fig4 #ad71 was made in ,pittsburgh as a part of the gift of apparatus by one of its citizens to the ,observatory1 and has been most useful4 ,by its aid the eye can be safely placed where the concentrated heat would otherwise melt iron4 ,in practice ,i have often gazed through it at the sun's face without intermission from four to five hours1 with no more fatigue or harm to the eye than in reading a book4 ,by its aid the observer fills in the outline already projected on the paper4 ,illustration3 ,,fig4 #ah4--8,,the ,,plume0 ,,spot ,,of ,,march #e ,,and #f1 #ahgc4 7,,from ,,an ,,original ,,drawing ,,by ,s4 ,p4 ,,langley47 ,the photograph has transported us already so near the sun's surface that we have seen details there invisible to the naked eye4 ,we have seen that what we have called 8spots0 are indeed regions whose actual vastness surpasses the vague immensity of a dream1 and it will not cause surprise that in them is a temperature which also surpasses greatly that of the hottest furnace4 ,we shall see later1 in fact1 that the whole surface is composed largely of metals turned into vapor in this heat1 and that if we could indeed drop our great globe itself upon the sun1 it would be dissipated as a snow-flake4 ,now1 we cannot suppose this great space is fully described when we have divided it into the penumbra1 umbra1 and nucleus1 or that the little photograph has shown us all there is1 and we rather anticipate that these great spaces must be filled with curious things1 if we could get near enough to see them4 ,we cannot advantageously enlarge our photograph further2 but if we could really come closer1 we should have the nearer view that the work at ,allegheny1 ,i have just alluded to1 now affords4 ,the drawing 7,fig4 #ae7 of the central part of the same great spot1 already cited1 was made on the #bast of ,september1 #ahgj1 and may be compared with the photograph of that day4 ,we have now a greatly more magnified view than before1 but it is not blurred by the magnifying1 and is full of detail4 ,we have been brought within two hundred thousand miles of the sun1 or rather less than the actual distance of the moon1 and are seeing for ourselves what was a few years since thought out of the reach of any observer4 ,see how full of intricate forms that void1 black1 umbral space in the photograph has become6 ,the penumbra is filled with detail of the strangest kind1 and there are two great 8bridges10 as they are called1 which are almost wholly invisible in the photograph4 ,notice the line in one of the bridges which follows its sinuosities through its whole length of twelve thousand miles1 making us suspect that it is made up of smaller parts as a rope is made up of cords 7as1 in fact1 it is72 and look at the end1 where the cords themselves are unravelled into threads fine as threads of silk1 and these again resolved into finer fibres1 till in more and more web-like fineness it passes beyond the reach of sight6 ,i am speaking1 however1 here rather of the wonderful original1 as ,i so well remember it1 than of what my sketch or even the engraver's skill can render4 ,illustration3 ,,fig4 #ai4--,,typical ,,sun ,,spot ,,of ,,december1 #ahgc4 7,,reduced ,,from ,,an ,,original ,,drawing ,,by ,s4 ,p4 ,,langley47 ,illustration3 ,,fig4 #bj4--;,,frost ,,crystal4 ,next we have quite another 8spot0 belonging to another year 7#ahgc74 ,first1 there is a view 7,fig4 #ag7 of the sun's disk with the spot on it 7as it would appear in a small telescope71 to show its relative size1 and then a larger drawing of the spot itself 7,fig4 #af71 on a scale of twelve thousand miles to the inch1 so that the region shown to the reader's eyes1 though but a 8spot0 on the sun1 covers an area of over one billion square miles1 or more than five times the entire surface of the earth1 land1 and water4 ,to help us to conceive its vastness1 ,i have drawn in one corner the continents of ,north and ,south ,america on the same scale as the 8spot40 ,notice the evidence of solar whirlwinds and the extraordinary 8plume0 7,fig4 #af71 which is a something we have no terrestrial simile for4 ,the appearance of the original would have been described most correctly by such incongruous images as 8leaf-like0 and 8crystalline0 and 8flame-like20 and even in this inadequate sketch there may remain some faint suggestion of the appearance of its wonderful archetype1 which was indeed that of a great flame leaping into spires and viewed through a window covered with frost crystals4 ,neither 8frost0 nor 8flame0 is really there1 but we cannot avoid this seemingly unnatural union of images1 which was fully justified by the marvellous thing itself4 ,the reader must bear in mind that the whole of this was actually in motion1 not merely turning with the sun's rotation1 but whirling and shifting within itself1 and that the motion was in parts occasionally probably as high as fifty miles per second1--per second1 remember1 not per hour1--so that it changed under the gazer's eyes4 ,the hook-shaped prominence in the lower part 7actually larger than the ,united ,states7 broke up and disappeared in about twenty minutes1 or while the writer was engaged in drawing it4 ,the imagination is confounded in an attempt to realize to itself the true character of such a phenomenon4 ,illustration3 ,,fig4 #ba4--;,,cyclone ,,spot4 7,,drawn ,,by ,,father ,,secchi47 ,on page #ai is a separate view of the plume 7,fig4 #ah71 a fac-simile of the original sketch1 which was made with the eye at the telescope4 ,the pointed or flame-like tips are not a very common form1 the terminals being more commonly clubbed1 like those in ,father ,secchi's 8branch of cactus0 type given on page #ab4 ,it must be borne in mind1 too1 if the drawing does not seem to contain all that the text implies1 that there were but a few minutes in which to attempt to draw1 where even a skilled draughtsman might have spent hours on the details momentarily visible1 and that much must be left to memory4 ,the writer's note-book at the time contains an expression of despair at his utter inability to render most of what he saw4 ,let us now look at another and even more wonderful example4 ,fig4 #ai shows part of a great spot which the writer drew in ,december1 #ahgc1 when the rare coincidence happened of a fine spot and fine terrestrial weather to observe it in4 ,in this1 as well as in the preceding drawing1 the pores which cover the sun's surface by millions may be noted4 ,the luminous dots which divide them are what ,nasmyth imperfectly saw1 but we are hardly more able than he to say what they really are4 ,each of these countless 8dots0 is larger than ,england1 ,scotland1 and ,ireland together6 ,the wonderful 8crystalline0 structure in the centre cannot be a real crystal1 for it is ten times the area of ,europe1 and changed slowly while ,i drew it2 but the reader may be sure that its resemblance to some crystallizations has not been in the least exaggerated4 ,i have sought to study various actual crystals for comparison1 but found none quite satisfactory4 ,that of sal-ammoniac in some remote way resembles it1 as ,secchi says2 but perhaps the frost crystals on a window-pane are better4 ,fig4 #bj shows one selected among several windows ,i had photographed in a preceding winter1 which has some suggestions of the so-called crystalline spot-forms in it1 but which lacks the filamentary thread-like components presently described4 ,of course the reader will understand that it is given as a suggestion of the appearance merely1 and that no similarity of nature is meant to be indicated4 ,illustration3 ,,fig4 #bb4--,,spot ,,of ,,march #ca1 #ahge4 7,,from ,,an ,,original ,,drawing ,,by ,s4 ,p4 ,,langley47 ,there were wonderful fern-like forms in this spot1 too1 and an appearance like that of pine-boughs covered with snow2 for1 strangely enough1 the intense whiteness of the solar surface in the best telescopes constantly suggests cold4 ,i have had the same impression vividly in looking at the immense masses of molten-white iron in a great puddling-furnace4 ,the salient feature here is one very difficult to see1 even in good telescopes1 but one which is of great interest4 ,it has been shown in the previous drawings1 but we have not enlarged on it4 ,everywhere in the spot are long white threads1 or filaments1 lying upon one another1 tending in a general sense toward the centre1 and each of which grows brighter toward its inner extremity4 ,these make up1 in fact1 as we now see1 the penumbra1 or outer shade1 and the so-called 8crystal0 is really affiliated to them4 ,besides this1 on closer looking we see that the inner shade1 or umbra1 and the very deepest shades1 or nuclei1 are really made of them too4 ,we can look into the dark centre1 as into a funnel1 to the depth of probably over five thousand miles2 but as far as we may go down we come to no liquid or solid floor1 and see only volumes of whirling vapor1 disposed not vaguely like our clouds1 but in the singularly definite1 fern-like1 flower-like forms which are themselves made of these 8filaments10 each of which is from three to five thousand miles long1 and from fifty to two hundred miles thick1 and each of which 7as we saw in the first spot7 appears to be made up like a rope of still finer and finer strands1 looking in the rare instants when irradiation makes an isolated one visible1 like a thread of gossamer or the finest of cobweb4 ,these suggest the fine threads of spun glass2 and here there is something more than a mere resemblance of form1 for both appear to have one causal feature in common1 due to a viscous or 8sticky0 fluid2 for there is much reason to believe that the solar atmosphere1 even where thinner than our own air1 is rendered viscous by the enormous heat1 and owes to this its tendency to pull out in strings in common with such otherwise dissimilar things as honey1 or melted sugar1 or melted glass4 ,we may compare those mysterious things1 the filaments1 to long grasses growing in the bed of a stream1 which show us the direction and the eddies of the current4 ,the likeness holds in more ways than one4 ,they are not lying1 as it were1 flat upon the surface of the water1 but within the medium2 and they do not stretch along in any one plane1 but they bend down and up4 ,moreover1 they are1 as we see1 apparently rooted at one end1 and their tips rise above the turbid fluid and grow brighter as they are lifted out of it4 ,but perhaps the most significant use of the comparison is made if we ask whether the stream is moving in an eddy like a whirlpool or boiling up from the ground4 ,the question in other words is1 8,are these spots themselves the sign of a mere chaotic disturbance1 or do they show us by the disposition of these filaments that each is a great solar maelstrom1 carrying the surface matter of the sun down into its body8 or1 finally1 are they just the opposite1--something comparable to fiery fountains or volcanoes on the earth1 throwing up to the surface the contents of the unknown solar interior80 ,illustration3 ,,fig4 #bc4--;,,cirrous ,,cloud4 7,,from ,a ,,photograph47 ,before we try to answer this question1 let us remember that the astonishing rapidity with which these forms change1 and still more the fact that they do not by any means always change by a bodily removal of one part from another1 but by a dissolving away and a fading out into invisibility1 like the melting of a cloud into thin air1--let us remember that all this assimilates them to something cloud-like and vaporous1 rather than crystalline1 and that1 as we have here seen1 we can ourselves pronounce from such results of recent observation that these are not lumps of scori floating on the solar furnace 7as some have thought them71 and still less1 literal crystals4 ,we can see for ourselves1 ,i believe1 that so far there is no evidence here of any solid1 or even liquid1 but that the surface of the sun is purely vaporous4 ,fig4 #bc shows a cirrous cloud in our own atmosphere1 caught for us by photography1 and which the reader will find it interesting to compare with the apparently analogous solar cloud-forms4 ,illustration3 ,,fig4 #bd4--,,spot ,,of ,,march #ca1 #ahge4 7,,from ,,an ,,original ,,drawing ,,by ,s4 ,p4 ,,langley47 8,vaporous10 we call them1 for want of a better word1 but without meaning that it is like the vapor of our clouds4 ,there is no exact terrestrial analogy for these extraordinary forms1 which are in fact1 as we shall see later1 composed of iron and other metals--not of solid iron nor even of liquid1 but iron heated beyond even the liquid state to that of iron-steam or vapor4 ,with all this in mind1 let us return to the question1 8,are the spots1 these gigantic areas of disturbance1 comparable to whirlpools or to volcanoes80 ,it may seem unphilosophical to assume that they are one or the other1 and in fact they may possibly be neither2 but it is certain that the surface of the sun would soon cool from its enormous temperature1 if it were not supplied with fresh heat1 and it is almost certain that this heat is drawn from the interior4 ,as ,m4 ,faye has pointed out1#a there must be a circulation up and down1 the cooled products being carried within1 heated and brought out again1 or the sun would1 however hot1 grow cold outside2 and1 what is of interest to us1 the earth would grow cold also1 and we should all die4 ,no one1 ,i believe1 who has studied the subject1 will contradict the statement that if the sun's surface were absolutely cut off from any heat supply from the interior1 organic life in general upon the earth 7and our own life in particular7 would cease much within a month4 ,this solar circulation1 then1 is of nearly as much consequence to us as that of our own bodies1 if we but knew it2 and now let us look at the spots again with this in mind4 #a ,to ,mr4 ,herbert ,spencer must be assigned the earliest suggestion of the necessity of such a circulation4 ,illustration3 ,,fig4 #be4--,,typical ,,illustration ,,of ,,faye',s ,,theory4 ,fig4 #ba shows a drawing by ,father ,secchi of a spot in #ahed2 and it is1 if unexaggerated1 quite the most remarkable case of distinct cyclonic action recorded4 ,i say 8if unexaggerated0 because there is a strong tendency in most designers to select what is striking in a spot1 and to emphasize that unduly1 even when there is no conscious disposition to alter4 ,every one who sketches may see a similar unconscious tendency in himself or herself1 shown in a disposition to draw all the mountains and hills too high1--a tendency on which ,ruskin1 ,i think1 has remarked4 ,in drawings of the sun there is a strong temptation to exaggerate these circular forms1 and we must not forget this in making up the evidence4 ,there is great need of caution1 then1 in receiving such representations2 but there certainly are forms which seem to be clearly due to cyclonic action4 ,they are usually scattered1 however1 through larger spots1 and ,i have never1 in all my study of the sun1 seen one such complete type of the cyclone spot as that first given from ,secchi4 ,instances where spots break up into numerous subdivisions by a process of 8segmentation0 under the apparent action of separate whirlwinds are much more common4 ,i have noticed1 as an apparent effect of this segmentation1 what ,i may call the 8honeycomb structure0 from its appearance with low powers1 but which with higher ones turns out to be made up of filamentary masses disposed in circular and ovoid curves1 often apparently overlying one another1 and frequently presenting a most curious resemblance to vegetable forms1 though we appear to see the real agency of whirlwinds in making them4 ,i add some transcripts of my original pencil memoranda themselves1 made with the eye at the telescope1 which1 though not at all finished drawings1 may be trusted the more as being quite literal transcripts at first hand4 ,illustration3 ,,fig4 #bf4--,,spot ,,of ,,oct4 #ac1 #ahgf4 7,,from ,,original ,,drawing ,,by ,s4 ,p4 ,,langley47 ,figs4 #bb and #bd1 for instance1 are two sketches of a little spot1 showing what1 with low powers1 gives the appearance ,i have called the honeycomb structure1 but which we see here to be due to whirls which have disposed the filaments in these remarkable forms4 ,the first was drawn at eleven in the forenoon of ,march #ca1 #ahge1 the second at three in the afternoon of the same day4 ,the scale of the drawing is fifteen thousand miles to the inch1 and the changes in this little spot in these few hours imply a cataclysm compared with which the disappearance of the ,american continent from the earth's surface would be a trifle4 ,the very act of the solar whirlwind's motion seemed to pass before my eyes in some of these sketches2 for while drawing them as rapidly as possible1 a new hole would be formed where there was none before1 as if by a gigantic invisible auger boring downward4 ,illustration3 ,,fig4 #bg4--,,photograph ,,of ,,edge ,,of ,,sun4 7,,by ,,permission ,,of ,,warren ,,de ,,la ,,rue1 ,,london47 ,m4 ,faye1 the distinguished ,french astronomer1 believes that1 owing to the fact that different zones of the sun rotate faster than others1 whirlwinds analogous to our terrestrial cyclones1 but on a vaster scale1 are set in motion1 and suck down the cooled vapors of the solar surface into its interior1 to be heated and returned again1 thus establishing a circulation which keeps the surface from cooling down4 ,he points out that we should not conclude that these whirlwinds are not acting everywhere1 merely because our bird's-eye view does not always show them4 ,we see that the spinning action of a whirlpool in water becomes more marked as we go below the surface1 which is comparatively undisturbed1 and we often see one whirl break up into several minor ones1 but all sucking downward and never upward4 ,according to ,m4 ,faye1 something very like this takes place on the sun1 and in ,fig4 #be he gives this section to show what he believes to occur in the case of a spot which has 8segmented10 or divided into two1 like the one whose 7imaginary7 section is shown above it4 ,this theory is to be considered in connection with such drawings as we have just shown1 which are themselves1 however1 no way dependent on theory1 but transcripts from ,nature4 ,i do not here either espouse or oppose the 8cyclonic0 theory1 but it is hardly possible for any one who has been an eyewitness of such things to refuse to regard some such disturbance as a real and efficient cause in such instances as this4 ,fig4 #bf1 on nearly the same scale as the last1 shows a spot which was seen on ,oct4 #ac1 #ahgf4 ,it looked at first1 in the telescope1 like two spots without any connection2 then1 as vision improved and higher powers were employed1 the two were seen to have a subtle bond of union1 and each to be filled with the most curious foliage-forms1 which ,i could only indicate in the few moments that the good definition lasted4 ,the reader may be sure1 ,i think1 that there is no exaggeration of the curious shapes of the original2 for ,i have been so anxious to avoid the overstatement of curvature that the error is more likely to be in the opposite direction4 ,we must conclude that the question as to the cyclonic hypothesis cannot yet be decided1 though the probabilities from telescopic evidence at present seem to me on the whole in favor of ,m4 ,faye's remarkable theory1 which has the great additional attraction to the student that it unites and explains numerous other quite disconnected facts4 ,turning now to the other solar features1 let us once more consider the sun as a whole4 ,fig4 #bg is a photograph taken from a part of the sun near its edge4 ,we notice on it1 what we see on every careful delineation of the sun1 that its general surface is not uniformly bright1 but that it grows darker as we approach the edge1 where it is marked by whiter mottlings called facul1 8something in the sun brighter than the sun itself10 and looking in the enlarged view which we present of one of them 7,fig4 #bh71 as if the surface of partly cooled metal in a caldron had been broken into fissures showing the brighter glow beneath4 ,these 8facul10 however1 are really above the solar surface1 not below it1 and what we wish to direct particular attention to is that darkening toward the edge which makes them visible4 ,illustration3 ,,fig4 #bh4--;,,facula4 7,,from ,a ,,drawing ,,by ,,chacornac47 ,this is very significant1 but its full meaning may not at first be clear4 ,it is owing to an atmosphere which surrounds the sun1 as the air does the earth4 ,when we look horizontally through our own air1 as at sunrise and sunset1 we gaze through greater thicknesses of it than when we turn our eyes to the zenith4 ,so when we look at the edge of the sun1 the line of sight passes through greater depths of this solar atmosphere1 and it dims the light shining behind it more than at the centre1 where it is thin4 ,this darkening toward the edge1 then1 means that the sun has an atmosphere which tempers its heat to us4 ,whatever the sun's heat supply is within its globe1 if this atmosphere grow thicker1 the heat is more confined within1 and our earth will grow colder2 if the solar atmosphere grow thinner1 the sun's energy will be expended more rapidly1 and our earth will grow hotter4 ,this atmosphere1 then1 is in considerable part1 at least1 the subject of the action of the spots2 this is what they are supposed to carry down or to spout up4 ,we shall return to the study of it again2 but what ,i want to point out now is that the temperature of the earth1 and even the existence of man upon it1 depends very much upon this1 at first sight1 insignificant phenomenon4 ,what1 then1 is the solar atmosphere8 ,is it a permanent thing8 ,not at all4 ,it is more light and unsubstantial than our own air1 and is being whirled about by solar winds as ours toss the dust of the streets4 ,it is being sucked down within the body of the sun by some action we do not clearly understand1 and returned to the surface by some counter effect which we comprehend no better2 and upon this imperfectly understood exchange depends in some way our own safety4 ,there used to be recorded in medical books the case of a boy who1 to represent ,phbus in a ,roman mask1 was gilded all over to produce the effect of the golden-rayed god1 but who died in a few hours because1 all the pores of the skin being closed by the gold-leaf1 the natural circulation was arrested4 ,we can count with the telescope millions of pores upon the sun's surface1 which are in some way connected with the interchange which has just been spoken of2 and if this1 his own natural circulation1 were arrested or notably diminished1 we should see his face grow cold1 and know that our own health1 with the life of all the human race1 was waiting on his recovery4 ,,ii4 ,,the ,,sun',s ,,surroundings4 ,as ,i write this1 the fields glitter with snow-crystals in the winter noon1 and the eye is dazzled with a reflection of the splendor which the sun pours so fully into every nook that by it alone we appear to see everything4 ,yet1 as the day declines1 and the glow of the sunset spreads up to the zenith1 there comes out in it the white-shining evening star1 which not the light1 but the darkness1 makes visible2 and as the last ruddy twilight fades1 not only this neighbor-world1 whose light is fed from the sunken sun1 but other stars appear1 themselves self-shining suns1 which were above us all through the day1 unseen because of the very light4 ,as night draws on1 we may see the occasional flash of a shooting-star1 or perhaps the auroral streamers spreading over the heavens2 and remembering that these will fade as the sun rises1 and that the nearer they are to it the more completely they will be blotted out1 we infer that if the sun were surrounded by a halo of only similar brightness1 this would remain forever invisible1--unless1 indeed1 there were some way of cutting off the light from the sun without obscuring its surroundings4 ,but if we try the experiment of holding up a screen which just conceals the sun1 nothing new is seen in its vicinity1 for we are also lighted by the neighboring sky1 which is so dazzlingly bright with reflected light as effectually to hide anything which may be behind it1 so that to get rid of this glare we should need to hang up a screen outside the earth's atmosphere altogether4 ,illustration3 ,,fig4 #bi4--,,lunar ,,cone ,,shadow4 ,nature hangs such a screen in front of the earth when the moon passes between it and the sun2 but as the moon is far too small to screen all the earth completely1 and as so limited a portion of its surface is in complete shadow that the chances are much against any given individual's being on the single spot covered by it1 many centuries usually elapse before such a total eclipse occurs at any given point2 while yet almost every year there may be a partial eclipse1 when1 over a great portion of the earth at once1 people may be able to look round the moon's edge and see the sunlight but partly cut off4 ,nearly every one1 then1 has seen a partial eclipse of the sun1 but comparatively few a total one1 which is quite another thing1 and worth a journey round the world to behold2 for such a nimbus1 or glory1 as we have suggested the possibility of1 does actually exist about the sun1 and becomes visible to the naked eye on the rare occasions when it is visible at all1 accompanied by phenomena which are unique among celestial wonders4 ,the 8corona10 as this solar crown is called1 is seen during a total eclipse to consist of a bright inner light next the invisible sun1 which melts into a fainter and immensely extended radiance 7the writer has followed the latter to the distance of about ten million miles71 and all this inner corona is filled with curious detail4 ,all this is to be distinguished from another remarkable feature seen at the same time2 for close to the black body of the moon are prominences of a vivid crimson and scarlet1 rising up like mountains from the hidden solar disk1 and these1 which will be considered later1 are quite distinct from the corona1 though seen on the background of its pearly light4 ,to understand what the lunar screen is doing for us1 we may imagine ourselves at some station outside the earth1 whence we should behold the moon's shadow somewhat as in ,fig4 #bi1 where we must remember that since the lunar orbit is not a circle1 but nearly an ellipse1 the moon is at some times farther from the earth than at others4 ,here the extremity of its shadow is represented as just touching the surface of the globe1 while it is evident that if the moon were at its greatest distance1 its shadow might come to a point before reaching the earth at all4 ,we speak1 of course1 only of the central cone of shade2 for there is an outer one1 indicated by the faint dotted lines1 within whose much more extended limits the eclipse is partial1 but with the latter we have at present nothing to do4 ,the figure however1 for want of room1 is made to represent the proportions incorrectly1 the real ones of the shadow being actually something like those of a sewing-needle1--this very long attenuated shadow sometimes1 as we have just said1 not reaching the earth at all1 and when it does reach it1 covering at the most a very small region indeed4 ,where this point touches1 and wherever it rests1 we should1 in looking down from our celestial station1 see that part of the earth in complete shadow1 appearing like a minute dark spot1 whose lesser diameter is seldom over a hundred and fifty miles4 ,the eclipse is total only to those inhabitants of the earth within the track of this dark spot1 though the spot itself travels across the earth with the speed of the moon in the sky2 so that if it could leave a mark1 it would in a few hours trace a dark line across the globe1 looking like a narrow black tape curving across the side of the world next the sun4 ,in ,fig4 #cj1 for instance1 is the central track of the eclipse of ,july #bi1 #ahgh1 as it would be visible to our celestial observer1 beginning in ,alaska in the forenoon1 and ending in the ,gulf of ,mexico1 which it reached in the afternoon4 ,to those on the earth's surface within this shadow it covered everything in view1 and1 for anything those involved in it could see1 it was all-embracing and terrible1 and worthily described in such lines as ,milton's1-- 8,as when the sun 444 ,in dim eclipse1 disastrous twilight sheds ,on half the nations1 and with fear of change ,perplexes monarchs40 ,we may enjoy the poet's vision2 but here1 while we look down on the whole earth at once1 we must admit that the actual area of the 8twilight0 is very small indeed4 ,within this area1 however1 the spectacle is one of which1 though the man of science may prosaically state the facts1 perhaps only the poet could render the impression4 ,we can faintly picture1 perhaps1 how it would seem1 from a station near the lunar orbit1 to see the moon--a moving world--rush by with a velocity greater than that of the cannon-ball in its swiftest flight2 but with equal speed its shadow actually travels along the earth4 ,and now1 if we return from our imaginary station to a real one here below1 we are better prepared to see why this flying shadow is such a unique spectacle2 for1 small as it may be when seen in relation to the whole globe1 it is immense to the observer1 whose entire horizon is filled with it1 and who sees the actual velocity of one of the heavenly bodies1 as it were1 brought down to him4 ,the reader who has ever ascended to the ,superga1 at ,turin1 will recall the magnificent view1 and be able to understand the good fortune of an observer 7,forbes7 who once had the opportunity to witness thence this phenomenon1 and under a nearly cloudless sky4 8,i perceived10 he says1 8in the southwest a black shadow like that of a storm about to break1 which obscured the ,alps4 ,it was the lunar shadow coming toward us40 ,and he speaks of the 8stupefaction0--it is his word--caused by the spectacle4 8,i confess10 he continues1 8it was the most terrifying sight ,i ever saw4 ,as always happens in the cases of sudden1 silent1 unexpected movements1 the spectator confounds real and relative motion4 ,i felt almost giddy for a moment1 as though the massive building under me bowed on the side of the coming eclipse40 ,another witness1 who had been looking at some bright clouds just before1 says3 8,the bright cloud ,i saw distinctly put out like a candle4 ,the rapidity of the shadow1 and the intensity1 produced a feeling that something material was sweeping over the earth at a speed perfectly frightful4 ,i involuntarily listened for the rushing noise of a mighty wind40 ,illustration3 ,,fig4 #cj--,,track ,,of ,,lunar ,,shadow4 ,each one notes something different from another at such a time2 and though the reader will find minute descriptions of the phenomena already in print1 it will perhaps be more interesting if1 instead of citations from books1 ,i invite him to view them with me1 since each can tell best what he has personally seen4 ,illustration3 ,,fig4 #ca4--;,,inner ,,corona ,,eclipse ,,of #ahfi4 ,,from ,,shelbyville ,,photograph4 7,,royal ,,astronomical ,,society',s ,,memoirs47 ,i have witnessed three total eclipses1 but ,i do not find that repetition dulls the interest4 ,the first was that of #ahfi1 which passed across the ,united ,states and was nearly central over ,louisville4 ,my station was on the southern border of the eclipse track1 not very far from the ,mammoth ,cave in ,kentucky1 and ,i well remember that early experience4 ,the special observations of precision in which ,i was engaged would not interest the reader2 but while trying to give my undivided attention to these1 a mental photograph of the whole spectacle seemed to be taking without my volition4 ,first1 the black body of the moon advanced slowly on the sun1 as we have all seen it do in partial eclipses1 without anything noticeable appearing2 nor till the sun was very nearly covered did the light of day about us seem much diminished4 ,but when the sun's face was reduced to a very narrow crescent1 the change was sudden and startling1 for the light which fell on us not only dwindled rapidly1 but became of a kind unknown before1 so that a pallid appearance overspread the face of the earth with an ugly livid hue2 and as this strange wanness increased1 a cold seemed to come with it4 ,the impression was of something unnatural2 but there was only a moment to note it1 for the sun went out as suddenly as a blown-out gas-jet1 and ,i became as suddenly aware that all around1 where it had been1 there had been growing into vision a kind of ghostly radiance1 composed of separate pearly beams1 looking distinct each from each1 as though the black circle where the sun once was1 bristled with pale streamers1 stretching far away from it in a sort of crown4 ,this was the mysterious corona1 only seen during the brief moments while the shadow is flying overhead2 but as ,i am undertaking to recall faithfully the impressions of the instant1 ,i may admit that ,i was at the time equally struck with a circumstance that may appear trivial in description1--the extraordinary globular appearance of the moon herself4 ,we all know well enough that the moon is a solid sphere1 but it commonly looks like a bright1 flat circle fastened to the concave of the starry vault2 and now1 owing to its unwonted illumination1 the actual rotundity was seen for the first time1 and the result was to show it as it really is1--a monstrous1 solid globe1 suspended by some invisible support above the earth1 with nothing apparent to keep it from tumbling on us1 looking at the moment very near1 and more than anything else like a gigantic black cannon-ball1 hung by some miracle in the air above the neighboring cornfield4 ,but in a few seconds all was over2 the sunlight flashed from one point of the moon's edge and then another1 almost simultaneously1 like suddenly kindled electric lights1 which as instantly flowed into one1 and it was day again4 ,illustration3 ,,fig4 #cb4--,,sketch ,,of ,,outer ,,corona1 #ahfi4 7,u4 ,s4 ,,coast ,,survey ,,report47 ,i have spoken of the 8unnatural0 appearance of the light just before totality4 ,this is not due to excited fancy1 for there is something so essentially different from the natural darkness of twilight1 that the brute creation shares the feeling with us4 ,arago1 for instance1 mentions that in the eclipse of #ahdb1 at ,perpignan1 where he was stationed1 a dog which had been kept from food twenty-four hours was1 to test this1 thrown some bread just before 8totality0 began4 ,the dog seized the loaf1 began to devour it ravenously1 and then1 as the appearance already described came on1 he dropped it4 ,the darkness lasted some minutes1 but not till the sun came forth again did the poor creature return to the food4 ,it is no wonder1 then1 that men also1 whether educated or ignorant1 do not escape the impression4 ,a party of the courtiers of ,louis ,,xv4 is said to have gathered round ,cassini to witness an eclipse from the terrace of the ,paris observatory1 and to have been laughing at the populace1 whose cries were heard as the light began to fade2 when1 as the unnatural gloom came quickly on1 a sudden silence fell on them too1 the panic terror striking through their laughter4 ,something common to man and the brute speaks at such times1 if never before or again2 something which is not altogether physical apprehension1 but more like the moral dismay when the shock of an earthquake is felt for the first time1 and we first know that startling doubt1 superior to reason1 whether the solid frame of earth is real1 and not 8baseless as the fabric of a vision40 ,but this is appealing for illustration to an experience which most readers have doubtless been spared1#b and ,i would rather cite the lighter one of our central party that day1 a few miles north of me1 at ,shelbyville4 ,in this part of ,kentucky the colored population was large1 and 7in those days7 ignorant of everything outside the life of the plantation1 from which they had only lately been emancipated4 ,on that eventful #hth of ,august they came in great numbers to view the enclosure and the tents of the observing party1 and to inquire the price of the show4 ,on learning that they might see it without charge from the outside1 a most unfavorable opinion was created among them as to the probable merits of so cheap a spectacle1 and they crowded the trees about the camp1 shouting to each other sarcastic comments on the inferior interest of the entertainment4 8,those trees there10 said one of the observers to me the next day1 8were black with them1 and they kept up their noise till near the last1 when they suddenly stopped1 and all at once1 and as #8totality' came1 we heard a wail and a noise of tumbling1 as though the trees had been shaken of their fruit1 and then the boldest did not feel safe till he was under his own bed in his own cabin40 #b ,this was written before the 8,charleston earthquake0 occurred4 ,illustration3 ,,fig4 #cc4--,,tacchini',s ,,drawing ,,of ,,corona ,,of #ahgj4 7,,secchi',s 8,,le ,,soleil407 ,it is impossible to give an exact view of what our friends at ,shelbyville saw1 for no drawings made there appear to have been preserved1 and photography at that time could only indicate feebly the portion of the corona near the sun where it is brightest4 ,fig4 #ca is a fac-simile of one of the photographs taken on the occasion1 which is interesting perhaps as one of the early attempts in this direction1 for comparison with later ones2 but as a picture it is very disappointing1 for the whole structure of the outer corona we have alluded to is missed altogether1 the plate having taken no impression of it4 ,a drawing 7,fig4 #cb7 made by another observer1 ,mr4 ,m',leod1 at ,springfield1 represents more of the outer structure2 but the reader must remember that all drawings must1 in the nature of the case 7since there are but two or three minutes to sketch in71 be incomplete1 whatever the artist's skill4 ,illustration3 ,,fig4 #cd4--,,watson',s ,,naked-,,eye ,,drawing ,,of ,,corona ,,of #ahgj4 7,u4 ,s4 ,,coast ,,survey ,,report47 ,up to this time it was still doubtful1 not only what the corona was1 but where it was2 whether it was a something about the sun or moon1 or whether1 indeed1 it might not be in our own atmosphere4 ,the spectroscopic observations of ,professors ,young and ,harkness at this same eclipse of a green line in its spectrum1 due to some glowing gas1 showed conclusively that it was largely1 at any rate1 a solar appendage1 and partly1 at least1 self-luminous2 and these and other results having awakened general discussion among astronomers in ,europe as well as at home1 the ,united ,states ,government sent an expedition1 under the direction of the late ,professor ,pierce1 to observe an eclipse which in the next year1 on ,dec4 #h1 #ahgj1 was total in the south of ,spain4 ,there were three parties2 and of the most western of these1 which was at ,xeres under the charge of ,professor ,winlock1 ,i was a member4 ,illustration3 ,,fig4 #ce4--,,photograph ,,showing ,,commencement ,,of ,,outer ,,corona4 7,,royal ,,astronomical ,,society',s ,,memoirs47 ,the duration of totality was known beforehand4 ,it would last two minutes and ten seconds1 and to secure what could be seen in this brief interval we crossed the ocean4 ,our station was in the midst of the sherry district1 and a part of the instruments were in an orange-grove1 where the ground was covered with the ripe fallen fruit1 while the olive and vine about us in ,december reminded us of the distance we had come to gather the results of so brief an opportunity4 ,to prepare for it1 we had all arrived on the ground some weeks beforehand1 and had been assiduously busy in installing the apparatus in the observing camp1 which suggested that of a small army1 the numerous instruments1 some of them of considerable size1--equatorials1 photographic apparatus1 polariscopes1 photometers1 and spectroscopes1--being under tents1 the fronts of which could be lifted when the time came for action4 ,to the equatorial telescopes photographic cameras are attached instead of the eye-pieces1 in the hope that the corona may be made to impress itself on the plate instead of on the eye4 ,the eye is an admirable instrument itself1 no doubt2 but behind it is a brain1 perhaps overwrought with excitement1 and responding too completely to the nervous tension which most of us experience when those critical moments are passing so rapidly4 ,the camera can see far less of the corona than the man1 but it has no nerves1 and what it sets down we may rely on4 ,at such a time each observer has some particular task assigned to him1 on which1 if wise1 he has drilled himself for weeks beforehand1 so that no hesitation or doubt may arise in the moment of action2 and his attention is expected to be devoted to this duty alone1 which may keep him from noting any of the features which make the occasion so impressive as a spectacle4 ,most of my own particular work was again of a kind which would not interest the reader4 ,apart from this1 ,i can recall little but the sort of pain of expectation1 as the moment approached1 till within a minute before totality the hum of voices around ceased1 and an utter and most impressive silence succeeded1 broken only by a low 8,ah60 from the group without the camp1 when the moment came4 ,i remember that the clouds1 which had hung over the sun while the moon was first advancing on its body1 cleared away before the instant of totality1 so that the last thing ,i saw was a range of mountains to the eastward still bright in the light2 then1 the next moment1 the shadow rushed overhead and blotted out the distant hills1 almost before ,i could turn my face to the instrument before me4 ,illustration3 ,,fig4 #cf4--;,,eclipse ,,of #aheg1 ,,drawing ,,by ,,liais4 7,,royal ,,astronomical ,,society',s ,,memoirs47 ,the corona appeared to me a different thing from what it did the year before4 ,it was apparently confined to a pearly light of a roughly quadrangular shape1 close to the limb of the sun1 broken by dark rifts 7one of which was a conspicuous object72 while within1 and close to the limb1 was what looked like a mountain rising from the hidden sun1 of the color of the richest tint we should see in a rose-leaf held up against the light1 while others were visible of an orange-scarlet4 ,after a short scrutiny ,i turned to my task of analyzing the nature of the white light4 ,the seconds fled1 the light broke out again1 and so did the hubbub of voices1--it was all over1 and what had been missed then could not be recovered4 ,the sense of self-reproach for wasted opportunity is a common enough feeling at this time1 though one may have done his best1 so little it seems to each he has accomplished2 but when all the results had been brought together1 we found that the spectroscopes1 cameras1 and polariscopes had each done their work1 and the journey had not been taken in vain4 ,in one point only we all differed1 and this was about the direct ocular evidence1 for each seemed to have seen a different corona1 and the drawings of it were singularly unlike4 ,here are two 7,figs4 #cc and #cd7 taken at this eclipse at the same time1 and from neighboring stations1 by two most experienced astronomers1 ,tacchini and ,watson4 ,no one could guess that they represented the same object1 and a similar discrepancy was common4 ,illustration3 ,,fig4 #cg4--;,,enlargement ,,of ,,part ,,of ,,fig4 #ch4 ,considering that these were trained experts1 whose special task it was1 in this case1 to draw the corona1 which therefore claimed their undivided attention1 ,i hardly know a more striking instance of the fallibility of human testimony4 ,the evidence of several observers1 however1 pointed to the fact that the light really was more nearly confined to the part next the sun than the year before1 so that the corona had probably changed during that interval1 and grown smaller1 which was remarkable enough4 ,the evidence of the polariscope1 on the whole1 showed it to be partly due to reflected sunlight1 while the spectroscope in the hands of ,professor ,young confirmed the last year's observation1 that it was also1 and largely1 self-luminous4 ,finally1 the photographs1 taken at very distant stations1 showed the same dark rifts in the same place1 and thus brought confirmatory evidence that it was not a local phenomenon in our own atmosphere4 ,a photograph of it1 taken by ,mr4 ,brothers in ,sicily1 is the subject of the annexed illustration 7,fig4 #ce71 in which the very bright lights which1 owing to 8photographic irradiation10 seem to indent the moon1 are chiefly due to the colored flames ,i have spoken of1 which will be described later4 ,it may be observed that the photographs taken in the next year 7#ahga7 were still more successful1 and began to show still more of the structure1 whose curious forms1 resembling large petals1 had already been figured by ,liais4 ,his drawing 7,fig4 #cf71 made in #aheg1 was supposed to be rather a fanciful sketch than a trustworthy one2 but1 as it will be seen1 the photograph goes far to justify it4 ,figures #cg and #ch are copies published by ,mr4 ,ranyard of the excellent photographs obtained in #ahga1 which are perhaps as good as anything done since1 though even these do not show the outer corona4 ,the first is an enlargement of a small portion of the detail in the second4 ,it is scarcely possible for wood-engraving to reproduce the delicate texture of the original4 ,illustration3 ,,fig4 #ch4--;,,fac-,,simile ,,of ,,photograph ,,of ,,corona ,,of #ahga4 7,,royal ,,astronomical ,,society',s ,,memoirs47 ,the years brought round the eclipse of #ahgh1 which was again in ,united ,states territory1 the central track 7as ,fig4 #cj has already shown7 running directly over one of the loftiest mountains of the country1 ,pike's ,peak1 in ,colorado4 ,pike's ,peak1 though over fourteen thousand feet high1 is often ascended by pleasure tourists2 but it is one thing to stay there for an hour or two1 and another to take up one's abode there and get acclimated1--for to do the latter we must first pass through the horrors 7not too strong a word7 of mountain-sickness4 ,this reaches its height usually on the second or third day1 and is something like violent sea-sickness1 complicated with the sensations a mouse may be supposed to have under the bell of an air-pump4 ,after a week the strong begin to get over it1 but none but the very robust should take its chances1 as we did1 without preparation2 for on the night before the eclipse the life of one of our little party was pronounced in danger1 and he was carried down in a litter to a cabin at an altitude of about ten thousand feet1 where he recovered so speedily as to be able to do good service on the following day4 ,the summit of the 8,peak0 is covered with great angular bowlders of splintered granite1 among which we laid logs brought up for firewood1 and on these1 sacks of damp hay1 then stretching a little tent over all and tying it down with wire to the rocks1 we were fain to turn in under damp blankets1 and to lie awake with incessant headache1 drawing long1 struggling breaths in the vain attempt to get air1 and wondering how long the tent would last1 as the canvas flapped and roared with a noise like that of a loose sail in a gale at sea1 with occasional intervals of a dead silence1 usually followed by a gust that shoved against the tent with the push of a solid body1 and if a sleepers shoulders touched the canvas1 shouldered him over in his bed4 ,the stout canvas held1 but the snow entered with the wind and lay in a deep drift on the pillow1 when ,i woke after a brief sleep toward morning1 and1 looking out on the gray dawn1 found that the snow had turned to hail1 which was rattling sharply on the rocks with an accompaniment of thunder1 which seemed to roll from all parts of the horizon4 ,the snow lay thick1 and the sheets of hail were like a wall1 shutting out the sight of everything a few rods off1 and this was in ,july6 ,i thought of my ,december station in sunny ,andalusia4 ,illustration3 ,,fig4 #ci4--8,,spectres40 ,hail1 rain1 sleet1 snow1 fog1 and every form of bad weather continued for a week on the summit1 while it was almost always clear below4 ,it was often a remarkable sight to go to the edge and look down4 ,the expanse of 8the plains10 which stretched eastward to a horizon line over a hundred miles distant1 would be in bright sunshine beneath1 while the hail was all around and above us2 and the light coming up instead of down gave singular effects when the clouds parted below1 the plains seeming at such times to be opalescent with luminous yellow and green1 as though the lower world were translucent1 and the sun were beneath it and shining up through4 ,fig4 #ci is a picture of three of us on the mountain-top1 who saw a rarer spectacle2 for directly opposite the setting sun1 and on the mist over the gulf beyond us1 was a bright ring1 in whose centre were three phantom images of our three selves1 which moved as we moved1 and then faded as the sun sank4 ,it was 8the spectre of the ,brocken40 ,these ghostly presentments were tolerably defined1 as in the sketch1 but did not seem to be gigantic1 as some have described them4 ,we rather thought them close at hand2 but before we could determine1 the vision faded4 ,the clouds1 to our good fortune1 rolled away on the #bith2 and a number of pleasure-seekers1 who came up to view the eclipse and the unwonted bright sunshine1 made a scene which it was hard to identify with the usual one4 ,this time my business was to draw the corona2 and the extreme altitude and the clearness of the air1 with perhaps some greater extension than usual in the object itself1 enabled it to be followed to an unprecedented distance4 ,during totality the sun was surrounded by a narrow ring--hardly more than a line--of vivid light1 presenting no structure to the naked eye 7but a remarkable one in the telescope72 and this faded with great suddenness into a circular nebulous luminosity between two and three diameters of the sun wide1 but without such marked plumes1 or filaments1 as ,i had seen in #ahfi4 ,the most extraordinary thing1 however1 was a beam of light1 inclined at an angle of about forty-five degrees1 about as wide as the sun1 and extending to the distance of nearly six of its diameters on one side and over twelve on the other2 on one side alone1 that is1 to the amazing distance of over ten million miles from its body4 ,substantially the same observation was made1 as it appeared later1 by ,professor ,newcomb1 at a lower level4 ,the direction1 when more carefully measured1 it was interesting to note1 coincided closely with that of the ,zodiacal light1 and a faint central rib added to its resemblance to that body4 ,it is noteworthy1 in illustration of what has already been said as to the conflict of ocular testimony1 that though ,i1 with the great majority of observers below1 saw only this beam1 two witnesses whose evidence is unimpeachable1 ,professors ,young and ,abbe1 saw a pale beam at right angles to it2 and that one observer did not see the beam in question at all4 ,fig4 #dj is a sketch made from my own1 but necessarily on a scale which can show only its general features4 ,with the telescope1 the whole of the bright inner light close to the sun was found to be made up of filaments1 more definite even than those described in a previous chapter as seen in sun-spots1 and bristling in all directions from the edge2 not concealing each other1 as we might expect such things to do1 upon a sphere1 but fringing the sun's edge in definite outline1 as though it were really but a disk4 ,illustration3 ,,fig4 #dj4--,,outer ,,corona ,,of #ahgh4 7,u4 ,s4 ,,naval ,,observatory47 ,those who were at leisure to watch the coming shadow of the moon described its curved outline as distinctly visible on the plains4 8,a rounded ball of darkness with an orange-yellow border10 one called it4 ,those1 again1 who looked down on the bright clouds below say the shadow was preceded by a yellow fringe1 casting a bright light over the clouds and passing into orange1 pink1 rose-red1 and dark-red1 in about twenty seconds4 ,this beautiful effect was noticed by nearly all the amateur observers present1 who had their attention at liberty1 and was generally unseen by the professional ones1 who were shut up in dark tents with photometers1 or engaged otherwise than in admiring the glory of the spectacle as a spectacle merely4 ,this strange light1 forming a band of color about the shadow as seen from above1 must have really covered ten miles or more in width1 and have occupied a considerable fraction of a minute in passing over the heads of those below1 to whom it probably constituted that lurid light on their landscape ,i have spoken of as so peculiar and 8unnatural40 ,it seems to be due to the colored flames round the sun1 which shine out when its brighter light is extinguished4 ,i should add that on the summit of ,pike's ,peak the corona did not entirely disappear at the instant the sun broke forth again1 but that its outlying portions first went and then its brighter and inner ones1 till our eager gaze1 trying to follow it as long as possible1 only after the lapse of some minutes saw the last of the wonderful thing disappear and 8fade into the light of common day40 ,illustration3 ,,fig4 #da4--,,spectrometer ,,slit ,,and ,,solar ,,image4 7,,from 8,,the ,,sun10 ,,by ,,young47 ,there have been other eclipses since2 but1 in spite of all1 our knowledge of the corona remains very incomplete1 and if the most learned in such matters were asked what it was1 he could probably answer truthfully1 8,i don't know40 ,illustration3 ,,fig4 #db4--,,slit ,,and ,,prominences4 78,,the ,,sun10 ,,by ,,young47 ,this will not be wondered at when it is considered that as total eclipses come1 about every other year1 and continue1 one with another1 hardly three minutes1 an astronomer who should devote thirty years exclusively to the subject1 never missing an eclipse in whatever quarter of the globe it occurred1 would in that time have secured1 in all1 something like three-quarters of an hour for observation4 ,accordingly1 what we know best about the corona is how it looks1 what it is being still largely conjecture2 and it is for this reason that ,i have thought the space devoted to it would be best used by giving the unscientific reader some idea of the visible phenomena as they present themselves to an eyewitness4 ,treatises like ,lockyer's 8,solar ,physics10 ,proctor's 8,the ,sun10 ,secchi's 8,le ,soleil10 and ,young's 8,the ,sun0 7the latter is most recent71 will give the reader who desires to learn more of the little that is known1 the fuller information which this is not the place for2 but it may be said very briefly that it is certain that the corona is at times of enormous extent 7the whole length of the longer beam seen on ,pike's ,peak must have been over fourteen million miles71 that it almost certainly changes in its shape and dimensions from year to year 7possibly much oftener1 but this we cannot yet know71 and that it shines partly by its own and partly by reflected light4 ,when we come to ask whether it is a gas or not1 the evidence is conflicting4 ,the appearance of the green coronal line1 and other testimony we have not alluded to1 would make it seem almost certain that there must be a gas here of extreme tenuity1 reaching the height of some hundred thousand miles1 at the least2 while yet the fact that such light bodies as comets have been known to pass through it1 close to the sun1 without suffering any visible retardation1 such as would come even from a gas far lighter than hydrogen1 appears to throw doubt on evidence otherwise strong4 ,it is possible to conceive of the corona1 and especially of the outer portion1 as very largely made up of minute particles such as form the scattered dust of meteoric trains1 and this seems to be the most probable constitution of its outlying parts4 ,it is even possible to conceive that it is in some degree a subjective phenomenon1 caused1 as ,professor ,hastings has suggested1 by diffraction upon the edge of the moon1--the moon1 that is1 not merely serving as a screen to the sun to reveal the corona1 but partly making the corona by diffracting the light1 somewhat as we see that the edge of any very distant object screening the sun is gilded by its beams4 ,this effect may be seen when the sun rises or sets unusually clear1 for objects on the horizon partly hiding it are then fringed for a moment with a line of light1--an appearance which has not escaped ,shakspeare1 where he says1-- 8,but when from under this terrestrial ball ,he fires the tall tops of the eastern pines40 ,still1 in admitting the possibility of some such contributory effect on the part of the moon1 we must not1 of course1 be understood as meaning that the corona as a whole does not have a real existence1 quite independent of the changes which the presence of the moon may bring2 and in leaving the wonderful thing we must remember that it is1 after all1 a reality1 and not a phantasm4 ,illustration3 ,,fig4 #dc4--,,tacchini',s ,,chromospheric ,,clouds4 78,,memorie ,,degli ,,spettroscopisti ,,italiani407 ,illustration3 ,,fig4 #dd4--,,tacchini',s ,,chromospheric ,,clouds4 78,,memorie ,,degli ,,spettroscopisti ,,italiani407 ,i have already described how1 at the eclipse of #ahgj1 ,i 7with others7 saw within the corona what seemed like rose and scarlet-colored mountains rising from the sun's edge1 an appearance which had first been particularly studied in the eclipse of #ahfh1 two years before1 and which1 it might be added1 ,messrs4 ,lockyer and ,janssen had succeeded in observing without an eclipse by the spectroscope4 ,besides the corona1 it may be said1 then1 that the sun is surrounded by a thin envelope1 rising here and there into prominences of a rose and scarlet color1 invisible in the telescope1 except at a total eclipse1 but always visible through the spectroscope4 ,it is within and quite distinct from the corona1 and is usually called the 8chromosphere10 being a sort of sphere of colored fire surrounding the sun1 but which we can usually see only on the edge4 8,the appearance10 says ,young1 8is as if countless jets of heated gas were issuing through vents and spiracles over the whole surface1 thus clothing it with flame1 which heaves and tosses like the blaze of a conflagration40 ,out of this1 then1 somewhat like greater waves or larger swellings of the colored fires1 rise the prominences1 whose place1 close to the sun's edge1 has been indicated in many of the drawings and photographs just given of the corona1 on whose background they are seen during eclipses2 but as they can be studied at our leisure with the spectroscope1 we have reserved a more particular description of them till now4 ,they are at all times directly before us1 as well as the corona2 but while both are yet invisible from the overpowering brightness of the sunlight reflected from the earth's atmosphere in front of them1 these red flames are so far brighter than the coronal background1 that if we could only weaken this 8glare0 a little1 they at least might become visible1 even if the corona were not4 ,the difficulty is evidently to find some contrivance which will weaken the 8glare0 without enfeebling the prominences too2 and this the spectroscope does by diffusing the white sunlight1 while it lets the color pass nearly unimpaired4 ,for the full understanding of its action the reader must be referred to such works as those on the sun already mentioned2 but a general idea of it may be gathered1 if we reflect that white light is composed of every possible variety of colors1 and that the spectroscope1 which consists essentially of a prism behind a very narrow slit through which the light enters1 lets any single color pass freely1 without weakening it or altering it in anything but its direction1 but gives a different direction to each1 and hence sorts out the tints1 distributing them side by side1 every one in its own place1 upon the long colored band called the spectrum4 ,if this distribution has spread the colors along a space a thousand times as wide as the original beam1 the average light must be just so much weaker than the white light was1 because this originally consisted of a thousand 7let us say a thousand1 but it is really an infinite number7 mingled tints of blue1 green1 yellow1 orange1 and red1 which have now been thus distributed4 ,if1 however1 we look through the prism at a rose-leaf1 and it has no blue1 green1 yellow1 or orange in it1 and nothing but pure red1 as each single color passes unchanged1 this red will1 according to what has been said1 be as bright after it has passed as before4 ,all depends1 then1 on the fact that these prominences do consist mainly of light of one color1 like the rose-leaf1 so that this monochromatic light will be seen through the spectroscope just as it is1 while the luminous veil of glaring white before it will seem to be brushed away4 ,if a large telescope be directed toward the sun1 the glass at the farther end will1 if we remove the eye-piece1 form a little picture of the sun1 as a picture is formed in a camera-obscura2 and now1 if we also fasten the spectroscope to this eye-end1 where the observer's head would be were he looking through1 the edge of the solar image may be made to fall just off the slit1 so that only the light from the prominences 7and the white glare about them7 shall pass in4 ,to see this more clearly1 let us turn our backs to the sun and the telescope1 and look at the place where the image falls by the spectroscope slit1 which in ,fig4 #da is drawn of its full size4 ,this is a brass plate1 having a minute rectangular window1 the 8slit10 in it4 ,the width of this slit is regulated by a screw1 and any rays falling into the narrow aperture pass through the prism within1 and finally fall on the observer's eye1 but not till they have been sorted by the prism in the manner described4 ,formed on the brass plate1 just as it would be formed on a sheet of paper1 or anything else held in the focus1 we see the bright solar image1 a circle of light perhaps an inch and a half in diameter1--a miniature of the sun with its spots4 ,the whole of the sun 7the photosphere7 then is hidden to an observer who is looking up through the slit from the other side1 for1 as the sun's edge does not quite touch the slit1 none of its rays can enter it2 but if there be also the image here of a prominence1 projecting beyond the edge1 and really overhanging the slit 7though to us invisible on account of the glare about it71 these rays will fall into the slit and pass down to the prism1 which will dispose of it in the way already stated4 ,illustration3 ,,fig4 #de4--,,vogel',s ,,chromospheric ,,forms4 78,,beobachtungen10 ,,dr4 ,h4 ,c4 ,,vogel47 ,and now let us get to the other side1 and1 looking up through the prism with the aid of a magnifying-glass1 see what it has done for us 7,fig4 #db74 ,the large rectangular opening here is the same as the small one which was visible from the outside1 only that it is now magnified1 and what was before invisible is seen2 the edge of the sun itself is just hidden1 but the scarlet flames of the chromosphere have become visible1 with a cloudy prominence rising above them4 ,the 8flames0 are flame-like only in form1 for their light is probably due not to any combustion1 but to the glow of intensely heated matter2 and as its light is not quite pure red1 we can1 by going to another part of the spectrum1 see the same thing repeated in orange1 the effect being as though we had a number of long narrow windows1 some glazed with red1 some with orange1 and some with other colors1 through which we could look out at the same clouds4 ,i have looked at these prominences often in this way2 but ,i prefer1 in the reader's interest1 to borrow from the description by ,professor ,young1 who has made these most interesting and wonderful forms a special study4 ,let us premise that the depth of the crimson shell out of which they rise is usually less than five thousand miles1 and that though the prominences vary greatly1 the majority reach a height of nearly twenty thousand miles1 while in exceptional cases this is immensely exceeded4 ,professor ,young has seen one which grew to a height of three hundred and fifty thousand miles in an hour and a half1 and in half an hour more had faded away4 ,these forms fall into two main classes1--that of the quiet and cloud-like1 and that of the eruptive1--the first being almost exactly in form like the clouds of our own sky1 sometimes appearing to lie on the limb of the sun like a bank of clouds on the horizon1 sometimes floating entirely free2 while sometimes 8the whole under surface is fringed with down-hanging filaments1 which remind one of a summer shower hanging from a heavy thunder-cloud40 ,here are some of the typical forms of the quieter ones3-- ,fig4 #dc1 by ,tacchini1 the ,director of the ,roman ,observatory1 represents an ordinary prominence1 or cloud-group in the chromosphere1 whose height is about twenty-five thousand miles4 ,the little spires of flame which rise1 thick as grass-blades1 everywhere from the surface1 are seen on its right and left4 ,illustration3 ,,fig4 #df4--,,tacchini',s ,,chromospheric ,,forms4 78,,memorie ,,degli ,,spettroscopisti ,,italiani407 ,fig4 #dd 7,tacchini7 is one where the agitation is greater and the 8filamentary0 type is more marked4 ,besides the curiously thread-like forms 7so suggestive of what we have already seen in the photosphere71 we have here what looks like an extended cloudy mass1 drawn out by a horizontally moving wind4 ,fig4 #de 7by ,vogel1 at ,bothkamp7 represents another of these numerous types4 ,the extraordinary ,fig4 #df is from another drawing1 by ,tacchini1 of a protuberance seen in #ahga 7a time of great solar disturbance71 and it belongs to the more energetic of its class4 ,illustration3 ,,fig4 #dg4--;,,eruptive ,,prominences4 78,,the ,,sun10 ,,by ,,young47 ,this fantastic cloud-shape1 8if shape it might be called that shape had none10 looking like some nightmare vision1 was about fifty thousand miles long and sixty thousand high above the surface4 ,the reader will notice also the fiery rain1 like the drops from a falling rocket1 and may add to it all1 in imagination1 the actual color1 which is of a deep scarlet4 ,it may add to the-interest such things excite1 to know that they have some mysterious connection with a terrestrial phenomenon1--the aurora1--for the northern lights have been again and again noticed to dance in company with these solar displays4 ,the eruptive prominences are very different in appearance1 as will be seen by the next illustration1 for which we are indebted to ,professor ,young4 ,in ,fig4 #dg we have a group of most interesting views by him 7drawn here on the common scale of seventy-five thousand miles to an inch71 illustrating the more eruptive types1 of which we will let him speak directly4 ,the first shows a case of the vertical filaments1 like those rocket-drops we saw just1 now in ,tacchini's drawing1 but here more marked2 while the second 7on the left side7 is a cyclone-form1 where the twisted stems suggest what we have seen before in the 8bridges0 of sun-spots1 and below this is another example of filamentary forms4 ,the upper one1 on the right1 is the view of a cloud prominence as it appeared at half-past twelve o'clock1 on ,sept4 #g1 #ahga4 ,below it is the same prominence at one o'clock 7half an hour later71 when it has been shattered by some inconceivable explosion1 blowing it into fragments1 and driving the hydrogen to a height of two hundred thousand miles4 ,the lowest figure on the right shows another case where inclined jets 7of hydrogen7 were seen to rise to a height of fifty thousand miles4 ,professor ,young says of these3-- 8,their form and appearance change with great rapidity1 so that the motion can almost be seen with the eye4 ,sometimes they consist of pointed rays1 diverging in all directions1 like hedgehog-spines4 ,sometimes they look like flames2 sometimes like sheaves of grain2 sometimes like whirling water-spouts1 capped with a great cloud2 occasionally they present most exactly the appearance of jets of liquid fire1 rising and falling in graceful parabolas2 frequently they carry on their edges spirals like the volutes of an ,ionic column2 and continually they detach filaments which rise to a great elevation1 gradually expanding and growing fainter as they ascend1 until the eye loses them4 ,there is no end to the number of curious and interesting appearances which they exhibit under varying circumstances4 ,the velocity of the motions often exceeds a hundred miles a second1 and sometimes1 though very rarely1 reaches two hundred miles40 ,in the case of the particular phenomenon recorded by ,professor ,young in the last illustration1 ,mr4 ,proctor1 however1 has calculated that the initial velocity probably exceeded five hundred miles a second1 which1 except for the resistance experienced by the sun's own atmosphere1 would have hurled the ejected matter into space entirely clear of the sun's power to recall it1 so that it would never return4 ,it adds to our interest in these flames to know that they at least are connected with that up-rush of heated matter from the sun's interior1 forming a part of the circulation which maintains both the temperature of its surface and that radiation on which all terrestrial life depends4 ,the flames1 indeed1 add of themselves little to the heat the sun sends us1 but they are in this way the outward and visible signs of a constant process within1 by which we live2 and so far they seem to have a more immediate interest to us1 though invisible1 than the corona which surrounds them4 ,but we must remember when we lift our eyes to the sun that this latter wonder is really there1 whether man sees it or not1 and that the cause of its existence is still unknown4 ,we ask for its 8object0 perhaps with an unconscious assumption that the whole must have been in some way provided to subserve our wants2 but there is not as yet the slightest evidence connecting its existence with any human need or purpose1 and as yet we have no knowledge that1 in this sense1 it exists to any 8end0 at all4 8,as the thought of man is widened with the process of the suns10 let us hope that we shall one day know more4 ,,iii4 ,,the ,,sun',s ,,energy4 8,it is indeed10 says good ,bishop ,berkeley1 8an opinion strangely prevailing amongst men that 444 all sensible objects have an existence 444 distinct from their being perceived by the understanding4 ,but 444 some truths there are1 so near and obvious to the mind1 that a man need only open his eyes to see them4 ,such ,i take this important one to be1 namely1 that all the choir of heaven and furniture of the earth--in a word1 all those bodies which compose the mighty frame of the world--have not any subsistence without a mind40 ,we are not going to take the reader along 8the high priori road0 of metaphysics1 but only to speak of certain accepted conclusions of modern experimental physics1 which do not themselves1 indeed1 justify all of ,berkeley's language1 but to which these words of the author of 8,a ,new ,theory of ,vision0 seem to be a not unfit prelude4 ,when we see a rose-leaf1 we see with it what we call a color1 and we are apt to think it is in the rose4 ,but the color is in us1 for it is a sensation which something coming from the sun excites in the eye2 so that if the rose-leaf were still there1 there would be no color unless there were an eye to receive and a brain to interpret the sensation4 ,every color that is lovely in the rainbow or the flower1 every hue that is vivid in a ribbon or sombre in the grave harmonies of some old ,persian rug1 the metallic lustre of the humming-bird or the sober imperial yellow of precious china1--all these have no existence as color apart from the seeing eye1 and all have their fount and origin in the sun itself4 8,color0 and 8light10 then1 are not1 properly speaking1 external things1 but names given to the sensations caused by an uncomprehended something radiated from the sun1 when this falls on our eyes4 ,if this very same something falls on our face1 it produces another kind of sensation1 which we call 8heat10 or if it falls on a thermometer it makes it rise2 while if it rests long on the face it will produce yet another effect1 8chemical action10 for it will tan the cheek1 producing a chemical change there2 or it will do the like work more promptly if it meet a photographic plate4 ,if we bear in mind that it is the identically same thing 7whatever that is7 which produces all these diverse effects1 we see1 some of us perhaps for the first time1 that 8color10 8light10 8radiant heat10 8actinism10 etc41 are only names given to the diverse effects of some thing1 not things themselves2 so that1 for instance1 all the splendor of color in the visible world exists only in the eye that sees it4 ,the reader must not suppose that he is here being asked to entertain any metaphysical subtlety4 ,we are considering a fact almost universally accepted within the last few years by physicists1 who now generally admit the existence of a something coming from the sun1 which is not itself light1 heat1 or chemical action1 but of which these are effects4 ,when we give this unknown thing a name1 we call it 8radiant energy40 ,how it crosses the void of space we cannot be properly said to know1 but all the phenomena lead us to think it is in the form of motion in some medium1--somewhat 7to use an imperfect analogy7 like the transmission through the air of the vibrations which will cause sound when they reach an ear4 ,this1 at any rate1 is certain1 that there is an action of some sort incessantly going on between us and the sun1 which enables us to experience the effects of light and heat4 ,we assume it to be a particular mode of vibration2 but whatever it is1 it is repeated with incomprehensible rapidity4 ,experiments recently made by the writer show that the slower heat vibrations which reach us from the sun succeed each other nearly #ajj1jjj1jjj1jjj1jjj times in a single second1 while those which make us see1 have long been known to be more rapid still4 ,these pass outward from the sun in every direction1 in ever-widening spheres2 and in them1 so far as we know1 lies the potency of life for the planet upon whose surface they fall4 ,did the reader ever consider that next to the mystery of gravitation1 which draws all things on the earth's surface down1 comes that mystery--not seen to be one because so familiar--of the occult force in the sunbeams which lifts things up8 ,the incomprehensible energy of the sunbeam brought the carbon out of the air1 put it together in the weed or the plant1 and lifted each tree-trunk above the soil4 ,the soil did not lift it1 any more than the soil in ,broadway lifted the spire of ,trinity4 ,men brought stones there in wagons to build the church1 and the sun brought the materials in its own way1 and built up alike the slender shaft that sustains the grass blade and the column of the pine4 ,if the tree or the spire fell1 it would require a certain amount of work of men or horses or engines to set it up again4 ,so much actual work1 at least1 the sun did in the original building2 and if we consider the number of trees in the forest1 we see that this alone is something great4 ,but besides this1 the sun locked up in each tree a store of energy thousands of times greater than that which was spent in merely lifting the trunk from the ground1 as we may see by unlocking it again1 when we burn the tree under the boiler of an engine2 for it will develop a power equal to the lifting of thousands of its kind1 if we choose to employ it in this way4 ,this is so true1 that the tree may fall1 and turn to coal in the soil1 and still keep this energy imprisoned in it1--keep it for millions of years1 till the black lump under the furnace gives out1 in the whirling spindles of the factory or the turning wheel of the steamboat1 the energy gathered in the sunshine of the primeval world4 ,the most active rays in building up plant-life are said to be the yellow and orange1 though ,nature's fondness for green everywhere is probably justified by some special utility4 ,at any rate1 the action of these solar rays is to decompose the products of combustion1 to set free the oxygen1 and to fix the carbon in the plant4 ,perhaps these words do not convey a definite meaning to the reader1 but it is to be hoped they will1 for the statement they imply is wonderful enough4 ,swift's philosopher at ,laputa1 who had a project for extracting sunbeams out of cucumbers1 was wiser than his author knew2 for cucumbers1 like other vegetables1 are now found to be really in large part put together by sunbeams1 and sunbeams1 or what is scarcely distinguishable from such1 could with our present scientific knowledge be extracted from cucumbers again1 only the process would be too expensive to pay4 ,the sunbeam1 however1 does what our wisest chemistry cannot do3 it takes the burned out ashes and makes them anew into green wood2 it takes the close and breathed out air1 and makes it sweet and fit to breathe by means of the plant1 whose food is the same as our poison4 ,with the aid of sunlight a lily would thrive on the deadly atmosphere of the 8black hole of ,calcutta20 for this bane to us1 we repeat1 is vital air to the plant1 which breathes it in through all its pores1 bringing it into contact with the chlorophyl1 its green blood1 which is to it what the red blood is to us2 doing almost everything1 however1 by means of the sun ray1 for if this be lacking1 the oxygen is no longer set free or the carbon retained1 and the plant dies4 ,this too brief statement must answer instead of a fuller description of how the sun's energy builds up the vegetable world4 ,but the ox1 the sheep1 and the lamb feed on the vegetable1 and we in turn on them 7and on vegetables too72 so that1 though we might eat our own meals in darkness and still live1 the meals themselves are provided literally at the sun's expense1 virtue having gone out of him to furnish each morsel we put in our mouths4 ,but while he thus prepares the material for our own bodies1 and while it is plain that without him we could not exist any more than the plant1 the processes by which he acts grow more intricate and more obscure in our own higher organism1 so that science as yet only half guesses how the sun makes us4 ,but the making is done in some way by the sun1 and so almost exclusively is every process of life4 ,it is not generally understood1 ,i think1 how literally true this is of every object in the organic world4 ,in a subsequent illustration we shall see a newspaper being printed by power directly and visibly derived from the sunbeam4 ,but all the power derived from coal1 and all the power derived from human muscles1 comes originally from the sun1 in just as literal a sense2 for the paper on which the reader's eye rests was not only made primarily from material grown by the sun1 but was stitched together by derived sun-power1 and by this1 also1 each page was printed1 so that the amount of this solar radiation expended for printing each chapter of this book could be stated with approximate accuracy in figures4 ,to make even the reader's hand which holds this page1 or the eye which sees it1 energy again went out from the sun2 and in saying this ,i am to be understood in the plain and common meaning of the words4 ,did the reader ever happen to be in a great cotton-mill1 where many hundreds of operatives watched many thousands of spindles8 ,nothing is visible to cause the multiplied movement1 the engine being perhaps away in altogether another building4 ,wandering from room to room1 where everything is in motion derived from some unseen source1 he may be arrested in his walk by a sudden cessation of the hum and bustle1--at once on the floor below1 and on that above1 and all around him4 ,the simultaneousness of this stoppage at points far apart when the steam is turned off1 strikes one with a sense of the intimate dependence of every complex process going on upon some remote invisible motor4 ,the cessation is not1 however1 absolutely instantaneous2 for the great fly-wheel1 in which a trifling part of the motor power is stored1 makes one or two turns more1 till the energy in this also is exhausted1 and all is still4 ,the coal-beds and the forests are to the sun what the fly-wheel is to the engine3 all their power comes from him2 they retain a little of it in store1 but very little by comparison with the original2 and were the change we have already spoken of to come over the sun's circulation1--were the solar engine disconnected from us1--we could go on perhaps a short time at the cost of this store1 but when this was over it would be over with us1 and all would be still here too4 ,is there not a special interest for us in that ,new ,astronomy which considers these things1 and studies the sun1 not only in the heavens as a star1 but in its workings here1 and so largely in its relations to man8 99 99 99 99 99 ,since1 then1 we are the children of the sun1 and our bodies a product of its rays1 as much as the ephemeral insects that its heat hatches from the soil1 it is a worthy problem to learn how things earthly depend upon this material ruler of our days4 ,but although we know it does nearly all things done on the earth1 and have learned a little of the way it builds up the plant1 we know so little of the way it does many other things here that we are still often only able to connect the terrestrial effect with the solar cause by noting what events happen together4 ,we are in this respect in the position of our forefathers1 who had not yet learned the science of electricity1 but who noted that when a flash of lightning came a clap of thunder followed1 and concluded as justly as ,franklin or ,faraday could have done that there was a physical relation between them4 ,quite in this way1 we who are in a like position with regard to the ,new ,astronomy1 which we hope will one day explain to us what is at present mysterious in our connection with the sun1 can as yet often only infer that when certain phenomena there are followed or accompanied by others here1 all are really connected as products of one cause1 however dissimilar they may look1 and however little we know what the real connection may be4 ,there is no more common inquiry than as to the influence of sun-spots on the weather2 but as we do not yet know the real nature of the connection1 if there be any1 we can only try to find out by assembling independent records of sun-spots and of the weather here1 and noticing if any changes in the one are accompanied by changes in the other2 to see1 for instance1 if when sun-spots are plenty the weather the world over is rainy or not1 or to see if when an unusual disturbance breaks out in a sun-spot any terrestrial disturbance is simultaneously noted4 ,illustration3 ,,fig4 #dh4--,,sun-,,spots ,,and ,,price ,,of ,,grain4 7,,from 8,,observations ,,of ,,solar ,,spots407 ,when we remember how our lives depend on a certain circulation in the sun1 of which the spots appear to be special examples1 it is of interest not only to study the forms within them1 as we have already been doing here1 but to ask whether the spots themselves are present as much one year as another4 ,the sun sometimes has numerous spots on it1 and sometimes none at all2 but it does not seem to have occurred to any one to see whether they had any regular period for coming or going1 till ,schwabe1 a magistrate in a little ,german town1 who happened to have a small telescope and a good deal of leisure1 began for his own amusement to note their number every day4 ,he commenced in #ahbf1 and with ,german patience observed daily for forty years4 ,he first found that the spots grew more numerous in #ahcj1 when there was no single day without one2 then the number declined very rapidly1 till in #ahcc they were about gone2 then they increased in number again till #ahch1 then again declined2 and so on1 till it became evident that sun-spots do not come and go by chance1 but run through a cycle of growth and disappearance1 on the average about once in every eleven years4 ,while amusing himself with his telescope1 an important sequence in ,nature had thus been added to our knowledge by the obscure ,hofrath ,schwabe1 who indeed compares himself to ,saul1 going out to seek his father's asses and finding a kingdom4 ,old records made before ,schwabe's time have since been hunted up1 so that we have a fairly connected history of the sun's surface for nearly a hundred and fifty years2 and the years when spots will be plentiful or rare can now be often predicted from seeing what has been in the past4 ,thus ,i may venture to say that the spots1 so frequent in #ahhe1 will have probably nearly disappeared in #ahhh1 and will be probably very plentiful in #ahid4 ,i do not know at all why this is likely to happen2 ,i only know that it has repeatedly happened at corresponding periods in the past4 8,now10 it may be asked1 8have these things any connection with weather changes1 and is it of any practical advantage to know if they have80 ,would it be1 it may be answered1 of any practical interest to a merchant in bread-stuffs to have private information of a reliable character that crops the world over would be fine in #ahhh and fail in #ahid8 ,the exclusive possession of such knowledge might plainly bring 8wealth beyond the dreams of avarice0 to the user2 or1 to ascend from the lower ground of personal interest to the higher aims of philanthropy and science1 could we predict the harvests1 we should be armed with a knowledge that might provide against coming years of famine1 and make life distinctly happier and easier to hundreds of millions of toilers on the earth's surface4 8,but can we predict80 ,we certainly cannot till we have1 at any rate1 first shown that there is a connection between sun-spots and the weather4 ,since we know nothing of the ultimate causes involved1 we can only at present1 as ,i say1 collect records of the changes there1 and compare them with others of the changes here1 to see if there is any significant coincidence4 ,to avoid columns of figures1 and yet to enable the reader to judge for himself in some degree of the evidence1 ,i will give the results of some of these records represented graphically by curves1 like those which he may perhaps remember to have seen used to show the fluctuations in the value of gold and grain1 or of stocks in the stock-market4 ,it is only fair to say that mathematicians used this method long before it was ever heard of by business men1 and that the stockbrokers borrowed it from the astronomers1 and not the astronomers from them4 ,in ,fig4 #dh1 from ,carrington's work1 each horizontal space represents ten years of time1 and the figures in the upper part represent the fluctuations of the sun-spot curve4 ,in the middle curve1 variations in vertical distances correspond to differences in the distance from the sun of the planet ,jupiter1 the possibility of whose influence on sun-spot periods can thus be examined4 ,in the third and lowest1 suggested by ,sir ,william ,herschel1 the figures at the side are proportional to the price of wheat in the ,english market1 rising when wheat ruled high1 falling when it was cheap4 ,in all three curves one-tenth of a horizontal spacing along the top or bottom corresponds to one year2 and in this way we have at a glance the condensed result of observations and statistics for sixty years1 which otherwise stated would fill volumes4 ,the result is instructive in more ways than one4 ,the variations of ,jupiter's distance certainly do present a striking coincidence with the changes in spot frequency1 and this may indicate a real connection between the phenomena2 but before we decide that it does so1 we must remember that the number of cycles of change presented by the possible combination of planetary periods is all but infinite4 ,thus we might safely undertake1 with study enough1 to find a curve1 depending solely on certain planetary configurations1 which yet would represent with quite striking agreement for a time the rise and fall in any given railroad stock1 the relative numbers of ,democratic and ,republican congressmen from year to year1 or anything else with which the heavenly bodies have in reality as little to do4 ,the third curve 7meant by the price of wheat to test the possible influence of sun-spots on years of good or bad harvests7 is not open to the last objection1 but involves a fallacy of another kind4 ,in fact the price of wheat depends on many things quite apart from the operations of ,nature1--on wars and legislation1 for instance2 and here the great rise in the first years of the century is as clearly connected with the great continental wars of the first ,napoleon1 which shut up foreign ports1 as the sudden fall about #ahae1 the year of ,waterloo1 is with the subsequent peace4 ,meanwhile an immense amount of labor has been spent in making tables of the weather1 and of almost every conceivable earthly phenomenon which may be supposed to have a similar periodic character1 with very doubtful success1 nearly every one having brought out some result which might be plausible if it stood alone1 but which is apt to be contradicted by the others4 ,for instance1 ,mr4 ,stone1 at the ,cape of ,good ,hope1 and ,dr4 ,gould1 in ,south ,america1 consider that the observations taken at those places show a little diminution of the earth's temperature 7amounting to one or two degrees7 at a sun-spot maximum4 ,mr4 ,chambers concludes1 from twenty-eight years' observations1 that the hottest are those of most sun-spots4 ,so each of these contradicts the other4 ,then we have ,gelinck1 who1 from a study of numerous observations1 concludes that all are wrong together1 and that there is really no change in either way4 ,illustration3 ,,fig4 #di4--,,sun-,,spot ,,of ,,nov4 #af1 #ahhb1 ,,and ,,earth4 ,i might go on citing names with no better result4 ,one observer tabulates observations of terrestrial temperature1 or rain-fall1 or barometer1 or ozone2 another1 the visitations of ,asiatic cholera2 while still another 7the late ,professor ,jevons7 tabulates commercial crises with the serious attempt to find a connection between the sun-spots and business panics4 ,of making such cycles there is no end1 and much study of them would be a weariness ,i will not inflict4 ,illustration3 ,,fig4 #ej4--;,,greenwich ,,record ,,of ,,disturbance ,,of ,,magnetic ,,needle1 ,,nov4 #af ,,and #ag1 #ahhb4 ,our own conclusion is1 that from such investigations of terrestrial changes nothing is yet certainly known with regard to the influence of sun-spots on the weather4 ,there is1 however1 quite another way2 that is1 to measure their effect at the origin in the sun itself4 ,the sun-spot is cooler than the rest of the surface1 and it might be thought that when there are many the sun would give less heat4 ,as far as the spots themselves are concerned1 this is so1 but in a very small degree4 ,i have been able to ascertain how much this deprivation of heat amounts to1 and find it is a real but a most insignificant quantity1 rising to about two-thirds of one degree ,fahrenheit every eleven years4 ,this1 it will be remembered1 is the direct effect of the spots considered merely as so many cool patches on the surface1 and it does not imply that when there are most spots the sun will necessarily give less heat4 ,in fact there may be a compensating action accompanying them which makes the radiation greater than when they are absent4 ,i will not enter on a detailed explanation1 but only say that in the best judgment ,i can form by a good deal of study and direct experiment1 there is no certain evidence that the sun is hotter at one time than at another4 ,if we investigate1 however1 the connection between spots and terrestrial magnetic disturbances1 we shall find altogether more satisfactory testimony4 ,this evidence is of all degrees of strength1 from probability up to what may be called certainty1 and it is always obtained1 not by a priori reasoning1 but by the comparison of independent observations of something which has happened on the sun and on the earth4 ,we will first take an instance of what we consider the weakest degree of evidence 7weak1 that is1 when any such single case is considered71 and we do so by simply quoting textually three records which were made at nearly the same time in different parts of the world in #ahhb4 ,a certain spot had been visible on the sun at intervals for some weeks2 but when on the #afth of ,november a glimpse was caught of it after previous days of cloudy weather1 the observer1 it will be seen1 is struck by the great activity going on in it1 and1 though familiar with such sights1 describes this one as 8magnificent40 #a4 ,from the daily record at the ,allegheny ,observatory1 ,november #af1 #ahhb3-- 8,very large spot on the sun2 444 great variety of forms2 inrush from ,s4 ,e4 to ,s4 ,w42 tendency to cyclonic action at several points4 ,the spot is apparently near its period of greatest activity4 ,a magnificent sight40 ,at the same time a sketch was commenced which was interrupted by the cloudy weather of this and following days4 ,the outline of the main spot only is here given 7,fig4 #di74 ,its area1 as measured at ,allegheny1 was #b1bjj1jjj1jjj square miles2 at ,greenwich its area1 inclusive of some outlying portions1 was estimated on the same day to be #b1fjj1jjj1jjj square miles4 ,the earth is shown of its relative size upon it1 to give a proper idea of the scale4 #b4 ,from the 8,new ,york ,tribune0 of ,november #ahth 7describing what took place in the night preceding the #agth73-- ,,an ,,electric ,,storm4 ,,telegraph ,,wires ,,greatly ,,affected4 ,,the ,,disturbance ,,wide-,,spread4 444 ,at the ,mutual ,union office the manager said1 8,our wires are all running1 but very slowly4 ,there is often an intermission of from one to five minutes between the words of a sentence4 ,the electric storm is general as far as our wires are concerned40444 ,the cable messages were also delayed1 in some cases as much as an hour4 ,the telephone service was practically useless during the day4 ,,washington1 ,nov4 #ag4--;,a magnetic storm of more than usual intensity began here at an early hour this morning1 and has continued with occasional interruptions during the day1 seriously interfering with telegraphic communication4444 ,as an experiment one of the wires of the ,western ,union ,telegraph ,company was worked between ,washington and ,baltimore this afternoon with the terrestrial current alone1 the batteries having been entirely detached4 ,,chicago1 ,nov4 #ag4--;,an electric storm of the greatest violence raged in all the territory to points beyond ,omaha4444 ,the switch-board here has been on fire a dozen times during the forenoon4 ,at noon only a single wire out of fifteen between this city and ,new ,york was in operation4 ,and so on through a column4 #c4 ,in ,fig4 #ej we give a portion of the automatic trace of the magnetic needles at ,greenwich4#c ,these needles are mounted on massive piers in the cellars of the observatory1 far removed from every visible source of disturbance1 and each carries a small mirror1 whence a spot of light is reflected upon a strip of photographic paper1 kept continually rolling before it by clock-work4 ,if the needle is still1 the moving strip of paper will have a straight line on it1 traced by the point of light1 which is in this case motionless4 ,if the needle swings to the right or left1 the light-spot vibrates with it1 and the line it traces becomes sinuous1 or more and more sharply zigzagged as the needle shivers under the unknown forces which control it4 #c ,it appears here through the kindness of the ,astronomer ,royal4 ,we regret to say that ,american observers are dependent on the courtesy of foreign ones in such matters1 the ,united ,states having no observatory where such records of sun-spots and magnetic variation are systematically kept4 ,the upper part of ,fig4 #ej gives a little portion of this automatic trace on ,november #afth before the disturbance began1 to show the ordinary daily record1 which should be compared with the violent perturbation occurring simultaneously with the telegraphic disturbance in the ,united ,states4 ,we may1 for the reader's convenience1 remark that as the astronomical day begins twelve hours later than the civil day1 the approximate ,washington mean times1 corresponding to the ,greenwich hours after twelve1 are found by adding one to the days and subtracting seventeen from the hours4 ,thus 8,november #afth1 twenty-two hours0 corresponds in the eastern ,united ,states nearly to five o'clock in the morning of ,november #agth4 ,the ,allegheny observer1 it will be remembered1 in his glimpse of the spot on ,november #afth1 was struck with the great activity of the internal motions then going on in it4 ,the ,astronomer ,royal states that a portion of the spot became detached on ,november #agth or #ahth1 and that several small spots which broke out in the immediate neighborhood were seen for the first time on the photographs taken ,november #agth1 twenty-two hours4 8,are we to conclude from this10 it may be asked1 8that what went on in the sun was the cause of the trouble on the telegraph wires80 ,i think we are not at all entitled to conclude so from this instance alone2 but though in one such case1 taken by itself1 there is nothing conclusive1 yet when such a degree of coincidence occurs again and again1 the habitual observer of solar phenomena learns to look with some confidence for evidence of electrical disturbance here following certain kinds of disturbance there1 and the weight of this part of the evidence is not to be sought so much in the strength of a single case1 as in the multitude of such coincidences4 ,we have1 however1 not only the means of comparing sun-spot years with years of terrestrial electric disturbance1 but individual instances1 particular minutes of sun-spot changes1 with particular minutes of terrestrial change2 and both comparisons are of the most convincing character4 ,first1 let us observe that the compass needle1 in its regular and ordinary behavior1 does not point constantly in any one direction through the day1 but moves a very little one way in the morning1 and back in the afternoon4 ,this same movement1 which can be noticed even in a good surveyor's compass1 is called the 8diurnal oscillation10 and has long been known4 ,it has been known1 too1 that its amount altered from one year to another2 but since ,schwabe's observations it has been found that the changes in this variation and in the number of the spots went on together4 ,the coincidences which we failed to note in the comparison of the spots with the prices of grain are here made out with convincing clearness1 as the reader will see by a simple inspection of this chart 7,fig4 #ea1 taken from ,professor ,young's work71 where the horizontal divisions still denote years1 and the height of the continuous curve the relative number of spots1 while the height of the dotted curve is the amount of the magnetic variation4 ,though we have given but a part of the curve1 the presumption from the agreement in the forty years alone would be a strong one that the two effects1 apparently so widely remote in their nature1 are really due to a common cause4 ,illustration3 ,,fig4 #ea4--,,sun-,,spots ,,and ,,magnetic ,,variations4 ,here we have compared years with years2 let us next compare minutes with minutes4 ,thus1 to cite 7from ,mr4 ,proctor's work7 a well-known instance3 ,on ,sept4 #a1 #ahfi1 at eighteen minutes past eleven1 ,mr4 ,carrington1 an experienced solar observer1 suddenly saw in the sun something brighter than the sun1--two patches of light1 breaking out so instantly and so intensely that his first thought was that daylight was entering through a hole in the darkening screen he used4 ,it was immediately1 however1 made certain that something unusual was occurring in the sun itself1 across which the brilliant spots were moving1 travelling thirty-five thousand miles in five minutes1 at the end of which time 7at twenty-three minutes past eleven7 they disappeared from sight4 ,by good fortune1 another observer a few miles distant saw and independently described the same phenomenon2 and as the minute had been noted1 it was immediately afterward found that recording instruments registered a magnetic disturbance at the same time1--8at the very moment10 says ,dr4 ,stewart1 the director of the observatory at ,kew4 8,by degrees10 says ,sir ,john ,herschel1 8accounts began to pour in of 444 great electro-magnetic disturbances in every part of the world4444 ,at ,washington and ,philadelphia1 in ,america1 the telegraphic signal men received severe electric shocks4 ,at ,boston1 in ,north ,america1 a flame of fire followed the pen of ,bain's electric telegraph40 7,such electric disturbances1 it may be mentioned1 are called 8electric storms10 though when they occur the weather may be perfectly serene to the eye4 ,they are shown also by rapid vibrations of the magnetic needle1 like those we have illustrated47 ,on ,aug4 #c1 #ahgb1 ,professor ,young1 who was observing at ,sherman in the ,rocky ,mountains1 saw three notable paroxysms in the sun's chromosphere1 jets of luminous matter of intense brilliance being projected at #h;h4 #dem41 #aj;h4 #cjm41 and #aa;h4 #ejm4 of the local time4 8,at dinner10 he says1 8the photographer of the party1 who was making our magnetic observations1 told me1 before knowing anything about what ,i had been observing1 that he had been obliged to give up work1 his magnet having swung clear off the limb40 ,similar phenomena were observed ,august #eth4 ,professor ,young wrote to ,england1 and received from ,greenwich and ,stonyhurst copies of the automatic record1 which he gives1 and which we give in ,fig4 #eb4 ,after allowing for difference of longitude1 the reader who will take the pains to compare them may see for himself that both show a jump of the needles in the cellars at ,greenwich at the same minute in each of the four cases of outburst in the ,rocky ,mountains4 ,illustration3 ,,fig4 #eb4--;,,greenwich ,,magnetic ,,observations1 ,,aug4 #c ,,and #e1 #ahgb4 ,while we admit that the evidence in any single case is rarely so conclusive as in these2 while we agree that the spot is not so much the cause of the change as the index of some other solar action which does cause it2 and while we fully concede our present ignorance of the nature of this cause1--we cannot refuse to accept the cumulative evidence1 of which a little has been submitted4 ,it is only in rare cases that we can feel quite sure2 and yet1 in regard even to one of the more common and less conclusive ones1 we may at least feel warranted in saying that if the reader forfeited a business engagement or missed an invitation to dinner through the failure of the telegraph or telephone on such an occasion as that of the #agth of ,november1 #ahhb1 the far-off sun-spot was not improbably connected with the cause4 ,probably we should all like to hear some at least equally positive conclusion about the weather also1 and to learn that there was a likelihood of our being able to predict it for the next year1 as the ,signal ,service now does for the next day2 but there is at present no such likelihood4 ,the study of the possible connection between sun-spots and the weather is1 nevertheless1 one that will always have great interest to many2 for even if we set its scientific aim aside and consider it in its purely utilitarian aspect1 it is evident that the knowledge how to predict whether coming harvests would be good or bad1 would enable us to do for the whole world what ,joseph's prophetic vision of the seven good and seven barren years did for the land of ,egypt1 and confer a greater power on its discoverer than any sovereign now possesses4 ,there is something to be said1 then1 for the cyclists2 for if their zeal does sometimes outrun knowledge1 their object is a worthy one1 and their aims such as we can sympathize with1 and of which none of us can say that there is any inherent impossibility in them1 or that they may not conceivably yet lead to something4 ,let us not1 then1 treat the inquirer who tries to connect panics on #8,change with sun-spots as a mere lunatic2 for there is this amount of reason in his theory1 that the panics1 together with the general state of business1 are connected in some obscure way with the good or bad harvests1 and these again in some still obscurer way with changes in our sun4 ,we may leave1 then1 this vision of forecasting the harvests and the markets of the world from a study of the sun1 as one of the fair dreams for the future of our science4 ,perhaps the dream will one day be realized4 ,who knows8 ,,iv4 ,,the ,,sun',s ,,energy 7,continued74 ,if we paused on the words with which our last chapter closed1 the reader might perhaps so far gather an impression that the whole all-important subject of the solar energy was involved in mystery and doubt4 ,but if it be indeed a mystery when considered in its essence1 so are all things2 while regarded separately in any one of its terrestrial effects of magnetic or chemical action1 or of light or heat1 it may seem less so4 ,since there is not room to consider all these aspects1 let us choose the last1 and look at this energy in its familiar form of the heat by which we live4 ,we1 the human race1 are warming ourselves at this great fire which called our bodies into being1 and when it goes out we shall go too4 ,what is it8 ,how long has it been8 ,how long will it last8 ,how shall we use it8 ,to look across the space of over ninety million miles1 and to try to learn from that distance the nature of the solar heat1 and how it is kept up1 seemed to the astronomers of the last century a hopeless task4 ,the difficulty was avoided rather than met by the doctrine that the sun was pure fire1 and shone because 8it was its nature to40 ,in the ,middle ,ages such an idea was universal2 and along with it1 and as a logical sequence of it1 the belief was long prevalent that it was possible to make another such flame here1 in the form of a lamp which should burn forever and radiate light endlessly without exhaustion4 ,with the philosopher's stone1 which was to transmute lead into gold1 this perpetual lamp formed a prime object of research for the alchemist and student of magic4 ,we recall the use which ,scott has made of the belief in this product of 8gramarye0 in the 8,lay of the ,last ,minstrel10 where it is sought to open the grave of the great wizard in ,melrose ,abbey4 ,it is midnight when the stone which covers it is heaved away1 and ,michael's undying lamp1 buried with him long ago1 shines out from the open tomb and illuminates the darkness of the chancel4 8,i would you had been there to see ,the light break forth so gloriously2 ,that lamp shall burn unquenchably ,until the eternal doom shall be10 says the poet4 ,now we are at liberty to enjoy the fiction as a fiction2 but if we admit that the art which could make such a lamp would indeed be a black art1 which did not work under ,nature's laws1 but against them1 then we ought to see that as the whole conception is derived from the early notion of a miraculous constitution of the sun1 the idea of an eternal self-sustained sun is no more permitted to us than that of an eternal self-sustained lamp4 ,we must look for the cause of the sun's heat in ,nature's laws1 and we know those laws chiefly by what we see here4 ,before examining the source of the sun's heat1 let us look a little more into its amount4 ,to find the exact amount of heat which it sends out is a very difficult problem1 especially if we are to use all the refinements of the latest methods in determining it4 ,the underlying principle1 however1 is embodied in an old method1 which gives1 it is true1 rather crude results1 but by so simple a treatment that the reader can follow it readily1 especially if unembarrassed with details1 in which most of the actual trouble lies4 ,we must warn him in advance that he is going to be confronted with a kind of enormous sum in multiplication1 for whose general accuracy he may1 however1 trust to us if he pleases4 ,we have not attempted exact accuracy1 because it is more convenient for him that we should deal with round numbers4 ,illustration3 ,,fig4 #ec4--,,one ,,cubic ,,centimetre4 ,illustration3 ,,fig4 #ed4--,,pouillet',s ,,pyrheliometer4 ,the apparatus which we shall need for the attack of this great problem is surprisingly simple1 and moderate in size4 ,let us begin by finding how much sun-heat falls in a small known area4 ,to do this we take a flat1 shallow vessel1 which is to be filled with water4 ,the amount it contains is usually a hundred cubic centimetres 7a centimetre being nearly four-tenths of an inch71 so that if we imagine a tiny cubical box about as large as a backgammon die1 or1 more exactly1 having each side just the size of this 7,fig4 #ec71 to be filled and emptied into the vessel one hundred times1 we shall have a precise idea of its limited capacity4 ,into this vessel we dip a thermometer1 so as to read the temperature of the water1 seal all up so that the water shall not run out1 and expose it so that the heat at noon falls perpendicularly on it4 ,the apparatus is shown in ,fig4 #ed1 attached to a tree4 ,the stem of the instrument holds the thermometer1 which is upside down1 its bulb being in the water-vessel4 ,now1 all the sun's rays do not reach this vessel1 for some are absorbed by our atmosphere2 and all the heat which falls on it does not stay there1 as the water loses part of it by the contact of the air with the box outside1 and in other ways4 ,when allowance is made for these losses1 we find that the sun's heat1 if all retained1 would have raised the temperature of the few drops of water which would fill a box the size of our little cube 7according to these latest observations7 nearly three degrees of the centigrade thermometer in one minute1--a most insignificant result1 apparently1 as a measure of what we have been told is the almost infinite heat of the sun6 ,but if we think so1 we are forgetting the power of numbers1 of which we are about to have an illustration as striking in its way as that which ,archimedes once gave with the grains of sand4 ,there is a treatise of his extant1 in which he remarks 7,i cite from memory7 that as some people believe it possible for numbers to express a quantity as great as that of the grains of sand upon the sea-shore1 while others deny this1 he will show that they can express one even larger4 ,to prove this beyond dispute1 he begins by taking a small seed1 beside which he ranges single grains of sand in a line1 till he can give the number of these latter which equal its length4 ,next he ranges seeds beside each other till their number makes up the length of a span2 then he counts the spans in a stadium1 and the stadia in the whole world as known to the ancients1 at each step expressing his results in a number certainly greater than the number of sand-grains which the seed1 or the span1 or the stadium1 or finally the whole world1 is thus successively shown to contain4 ,he has then already got a number before his reader's eyes demonstrably larger than that of all the grains of sand on the sea-shore2 yet he does not stop1 but steps off the earth into space1 to calculate and express a number greater than that of all the grains of sand which would fill a sphere embracing the earth and the sun6 ,we are going to use our little unit of heat in the same way1 for 7to calculate in round figures and in ,english measure7 we find that we can set over nine hundred of these small cubes side by side in a square foot1 and1 as there are #bh1jjj1jjj feet in a square mile1 that the latter would contain #be1jjj1jjj1jjj of the cubes1 placed side by side1 touching each other1 like a mosaic pavement4 ,we find also1 by weighing our little cup1 that we should need to fill and empty it almost exactly a million times to exhaust a tank containing a ton of water4 ,the sun-heat falling on one square mile corresponds1 then1 to over seven hundred and fifty tons of water raised every minute from the freezing-point to boiling1 which already is becoming a respectable amount6 ,but there are #di1jjj1jjj square miles in the cross-section of the earth exposed to the sun's rays1 which it would therefore need #a1bbe1jjj1jjj1jjj1jjj1jjj of our little dies to cover one deep2 and therefore in each minute the sun's heat falling on the earth would raise to boiling #cg1jjj1jjj1jjj tons of water4 ,we may express this in other ways1 as by the quantity of ice it would melt2 and as the heat required to melt a given weight of ice is #gi_/ajj of that required to bring as much water from the freezing to the boiling point1 and as the whole surface of the earth1 including the night side1 is four times the cross-section exposed to the sun1 we find1 by taking #ebf1jjj minutes to a year1 that the sun's rays would melt in the year a coating of ice over the whole earth more than one hundred and sixty feet thick4 ,we have ascended already from our small starting-point to numbers which express the heat that falls upon the whole planet1 and enable us to deal1 if we wish1 with questions relating to the glacial epochs and other changes in its history4 ,we have done this by referring at each step to the little cube which we have carried along with us1 and which is the foundation of all the rest2 and we now see why such exactness in the first determination is needed1 since any error is multiplied by enormous numbers4 ,but now we too are going to step off the earth and to deal with numbers which we can still express in the same way if we choose1 but which grow so large thus stated that we will seek some greater term of comparison for them4 ,we have just seen the almost incomprehensible amount of heat which the sun must send the earth in order to warm its oceans and make green its continents2 but how little this is to what passes us by6 ,the earth as it moves on in its annual path continually comes into new regions1 where it finds the same amount of heat already pouring forth2 and this same amount still continues to fall into the empty space we have just quitted1 where there is no one left to note it1 and where it goes on in what seems to us utter waste4 ,if1 then1 the whole annual orbit were set close with globes like ours1 and strung with worlds like beads upon a ring1 each would receive the same enormous amount the earth does now4 ,but this is not all2 for not only along the orbit1 but above and below it1 the sun sends its heat in seemingly incredible wastefulness1 the final amount being expressible in the number of worlds like ours that it could warm like ours1 which is #b1bjj1jjj1jjj4 ,we have possibly given a surfeit of such numbers1 but we cannot escape or altogether avoid them when dealing with this stupendous outflow of the solar heat4 ,they are too great1 perhaps1 to convey a clear idea to the mind1 but let us before leaving them try to give an illustration of their significance4 ,let us suppose that we could sweep up from the earth all the ice and snow on its surface1 and1 gathering in the accumulations which lie on its ,arctic and ,antarctic poles1 commence building with it a tower greater than that of ,babel1 fifteen miles in diameter1 and so high as to exhaust our store4 ,imagine that it could be preserved untouched by the sun's rays1 while we built on with the accumulations of successive winters1 until it stretched out #bdj1jjj miles into space1 and formed an ice-bridge to the moon1 and that then we concentrated on it the sun's whole radiation1 neither more nor less than that which goes on every moment4 ,in one second the whole would be gone1 melted1 boiled1 and dissipated in vapor4 ,and this is the rate at which the solar heat is being 7to human apprehension7 wasted6 ,nature1 we are told1 always accomplishes her purpose with the least possible expenditure of energy4 ,is her purpose here1 then1 something quite independent of man's comfort and happiness8 ,of the whole solar heat1 we have just seen that less than #a_/b1jjj1jjj1--less1 that is1 than the one twenty-thousandth part of one per cent1--is made useful to us4 8,but may there not be other planets on which intelligent life exists1 and where this heat1 which passes us by1 serves other beings than ourselves80 ,there may be2 but if we could suppose all the other planets of the solar system to be inhabited1 it would help the matter very little2 for the whole together intercept so little of the great sum1 that all of it which ,nature bestows on man is still as nothing to what she bestows on some end--if end there be--which is to us as yet inscrutable4 ,how is this heat maintained8 ,not by the miracle of a perpetual self-sustained flame1 we may be sure4 ,but1 then1 by what fuel is such a fire fed8 ,there can be no question of simple burning1 like that of coal in the grate1 for there is no source of supply adequate to the demand4 ,the ,state of ,pennsylvania1 for instance1 is underlaid by one of the richest coal-fields of the world1 capable of supplying the consumption of the whole country at its present rate for more than a thousand years to come4 ,if the source of the solar heat 7whatever that is7 were withdrawn1 and we were enabled to carry this coal there1 and shoot it into the solar furnace fast enough to keep up the known heat-supply1 so that the solar radiation would go on at just its actual rate1 the time which this coal would last is easily calculable4 ,it would not last days or hours1 but the whole of these coal-beds would demonstrably be used up in rather less than one one-thousandth of a second6 ,we find by a similar calculation that if the sun were itself one solid block of coal1 it would have burned out to the last cinder in less time than man has certainly been on the earth4 ,but during historic times there has as surely been no noticeable diminution of the sun's heat1 for the olive and the vine grow just as they did three thousand years ago1 and the hypothesis of an actual burning becomes untenable4 ,it has been supposed by some that meteors striking the solar surface might generate heat by their impact1 just as a cannon-ball fired against an armor-plate causes a flash of light1 and a heat so sudden and intense as to partly melt the ball at the instant of concussion4 ,this is probably a real source of heat-supply so far as it goes1 but it cannot go very far2 and1 indeed1 if our whole world should fall upon the solar surface like an immense projectile1 gathering speed as it fell1 and finally striking 7as it would7 with the force due to a rate of over three hundred miles a second1 the heat developed would supply the sun for but little more than sixty years4#d #d ,these estimates differ somewhat from those of ,helmholtz and ,tyndall1 as they rest on later measures4 ,it is not necessary1 however1 that a body should be moving rapidly to develop heat1 for arrested motion always generates it1 whether the motion be fast or slow1 though in the latter case the mass arrested must be larger to produce the same result4 ,it is in the slow settlement of the sun's own substance toward its centre1 as it contracts in cooling1 that we find a sufficient cause for the heat developed4 ,this explanation is often unsatisfactory to those who have not studied the subject1 because the fact that heat is so generated is not made familiar to most of us by observation4 ,perhaps the following illustration will make the matter plainer4 ,when we are carried up in a lift1 or elevator1 we know well enough that heat has been expended under the boiler of some engine to drag us up against the power of gravity4 ,when the elevator is at the top of its course1 it is ready to give out in descending just the same amount of power needed to raise it1 as we see by its drawing up a nearly equal counterpoise in the descent4 ,it can and must give out in coming down the power that was spent in raising it up2 and though there is no practical occasion to do so1 a large part of this power could1 if we wished1 be actually recovered in the form of heat again4 ,in the case of a larger body1 such as the pyramid of ,ghizeh1 which weighs between six and seven million tons1 all the furnaces in the world1 burning coal under all its engines1 would have to supply their heat for a measurable time to lift it a mile high2 and then1 if it were allowed to come down1 whether it tell at once or were made to descend with imperceptible slowness1 by the time it touched the earth the same heat would be given out again4 ,perhaps the fact that the sun is gaseous rather than solid makes it less easy to realize the enormous weight which is consistent with this vaporous constitution4 ,a cubic mile of hydrogen gas 7the lightest substance known7 would weigh much more at the sun's surface than the ,great ,pyramid does here1 and the number of these cubic miles in a stratum one mile deep below its surface is over #b1jjj1jjj1jjj1jjj6 ,this alone is enough to show that as they settle downward as the solar globe shrinks1 here is a possible source of supply for all the heat the sun sends out4 ,more exact calculation shows that it is sufficient1 and that a contraction of three hundred feet a year 7which in ten thousand years would make a shrinkage hardly visible in the most powerful telescope7 would give all the immense outflow of heat which we see4 ,there is an ultimate limit1 however1 to the sun's shrinking1 and there must have been some bounds to the heat he can already have thus acquired2 for--though the greater the original diameter of his sphere1 the greater the gain of heat by shrinking to its present size--if the original diameter be supposed as great as possible1 there is still a finite limit to the heat gained4 ,suppose1 in other words1 the sun itself and all the planets ground to powder1 and distributed on the surface of a sphere whose radius is infinite1 and that this matter 7the same in amount as that constituting the present solar system7 is allowed to fall together at the centre4 ,the actual shrinkage cannot possibly be greater than in this extreme case2 but even in this practically impossible instance1 it is easy to calculate that the heat given out would not support the present radiation over eighteen million years1 and thus we are enabled to look back over past time1 and fix an approximate limit to the age of the sun and earth4 ,we say 8present0 rate of radiation1 because1 so long as the sun is purely gaseous1 its temperature rises as it contracts1 and the heat is spent faster2 so that in early ages before this temperature was as high as it is now1 the heat was spent more slowly1 and what could have lasted 8only0 eighteen million years at the present rate might have actually spread over an indefinitely greater time in the past2 possibly covering more than all the ons geologists ask for4 ,if we would look into the future1 also1 we find that at the present rate we may say that the sun's heat-supply is enough to last for some such term as four or five million years before it sensibly fails4 ,it is certainly remarkable that by the aid of our science man can look out from this 8bank and shoal of time10 where his fleeting existence is spent1 not only back on the almost infinite lapse of ages past1 but that he can forecast with some sort of assurance what is to happen in an almost infinitely distant future1 long after the human race itself will have disappeared from its present home4 ,but so it is1 and we may say--with something like awe at the meaning to which science points--that the whole future radiation cannot last so long as ten million years4 ,its probable life in its present condition is covered by about thirty million years4 ,no reasonable allowance for the fall of meteors or for all other known causes of supply could possibly at the present rate of radiation raise the whole term of its existence to sixty million years4 ,this is substantially ,professor ,young's view1 and he adds3-- 8,at the same time it is1 of course1 impossible to assert that there has been no catastrophe in the past1 no collision with some wandering star 444 producing a shock which might in a few hours1 or moments even1 restore the wasted energy of ages4 ,neither is it wholly safe to assume that there may not be ways1 of which we as yet have no conception1 by which the energy apparently lost in space may be returned4 ,but the whole course and tendency of ,nature1 so far as science now makes out1 points backward to a beginning and forward to an end4 ,the present order of things seems to be bounded both in the past and in the future by terminal catastrophes which are veiled in clouds as yet inscrutable40 ,there is another matter of interest to us as dwellers on this planet1 connected not with the amount of the sun's heat so much as with the degree of its temperature2 for it is almost certain that a very little fall in the temperature will cause an immense and wholly disproportionate diminution of the heat-supply4 ,the same principle may be observed in more familiar things4 ,we can1 for instance1 warm quite a large house by a very small furnace1 if we urge this 7by a wasteful use of coal7 to a dazzling white heat4 ,if we now let the furnace cool to half this white-heat temperature1 we shall be sure to find that the heat radiated has not diminished in proportion1 but out of all proportion1--has sunk1 for instance1 not only to one-half what it was 7as we might think it would do71 but to perhaps a twentieth or even less1 so that the furnace which heated the house can no longer warm a single room4 ,the human race1 as we have said1 is warming itself at the great solar furnace1 which we have just seen contains an internal source for generating heat enough for millions of years to come2 but we have also learned that if the sun's internal circulation were stopped1 the surface would cool and shut up the heat inside1 where it would do us no good4 ,the temperature of the surface1 then1 on which the rate of heat-emission depends1 concerns us very much2 and if we had a thermometer so long that we could dip its bulb into the sun and read the degrees on the stem here1 we should find out what observers would very much like to know1 and at present are disposed to quarrel about4 ,the difficulty is not in measuring the heat1--for that we have just seen how to do1--but in telling what temperature corresponds to it1 since there is no known rule by which to find one from the other4 ,one certain thing is this--that we cannot by any contrivance raise the temperature in the focus of any lens or mirror beyond that of its source 7practically we cannot do even so much72 we cannot1 for instance1 by any burning-lens make the image of a candle as hot as the original flame4 ,whatever a thermometer may read when the candle-heat is concentrated on its bulb by a lens1 it would read yet more if the bulb were dipped in the candle-flame itself2 and one obvious application of this fact is that though we cannot dip our thermometer in the sun1 we know that if we could do so1 the temperature would at least be greater than any we get by the largest burning-glass4 ,we need have no fear of making the burning-glass too big2 the temperature at its solar focus is always and necessarily lower than that of the sun itself4 ,for some reason no very great burning-lens or mirror has been constructed for a long time1 and we have to go back to the eighteenth century to see what can be done in this way4 ,the annexed figure 7,fig4 #ee7 is from a wood-cut of the last century1 describing the largest burning-lens then or since constructed in ,france1 whose size and mode of use the drawing clearly shows4 ,all the heat falling on the great lens was concentrated on a smaller one1 and the smaller one concentrated it in turn1 till at the very focus we are assured that iron1 gold1 and other metals ran like melted butter4 ,in ,england1 the largest burning-lens on record was made about the same time by an optician named ,parker for the ,english ,government1 who designed it as a present to be taken by ,lord ,macartney's embassy to the ,emperor of ,china4 ,parker's lens was three feet in diameter and very massive1 being seven inches thick at the centre4 ,in its focus the most refractory substances were fused1 and even the diamond was reduced to vapor1 so that the temperature of the sun's surface is at any rate higher than this4 ,illustration3 ,,fig4 #ee4--;,,berni,,res',s ,,great ,,burning-,,glass4 7,,after ,,an ,,old ,,french ,,print47 7,what became of the ,french lens shown1 it would be interesting to know4 ,if it is still above ground1 its fate has been better than that of the ,english one4 ,it is said that the ,emperor of ,china1 when he got his lens1 was much alarmed by it1 as being possibly sent him by the ,english with some covert design for his injury4 ,by way of a test1 a smith was ordered to strike it with his hammer2 but the hammer rebounded from the solid glass1 and this was taken to be conclusive evidence of magic in the thing1 which was immediately buried1 and probably is still reposing under the soil of the ,celestial ,flowery ,kingdom47 ,we can confirm the evidence of such burning-lenses as to the sun's high temperature by another class of experiment1 which rests on an analogous principle4 ,we can make the comparison between the heat from some artificially heated object and that which would be given out from an equal area of the sun's face4 ,now1 supposing like emissive powers1 if the latter be found the hotter1 though we cannot tell what its temperature absolutely is1 we can at least say that it is greater than that of the thing with which it is compared2 so that we choose for comparison the hottest thing we can find1 on a scale large enough for the experiment4 ,one observation of my own in this direction ,i will permit myself to cite in illustration4 ,perhaps the highest temperature we can get on a large scale in the arts is that of molten steel in the ,bessemer converter4 ,as many may be as ignorant of what this is as ,i was before ,i tried the experiment1 ,i will try to describe it4 ,illustration3 ,,fig4 #ef4--;,a 8,,pour0 ,,from ,,the ,,bessemer ,,converter4 ,the 8converter0 is an enormous iron pot1 lined with fire-brick1 and capable of holding thirty or forty thousand pounds of melted metal2 and it is swung on trunnions1 so that it can be raised by an engine to a vertical position1 or lowered by machinery so as to pour its contents out into a caldron4 ,first the empty converter is inclined1 and fifteen thousand pounds of fluid iron streams down into the mouth from an adjacent furnace where it has been melted4 ,then the engine lifts the converter into an erect position1 while an air-blast from a blowing-engine is forced in at the bottom and through the liquid iron1 which has combined with it nearly half a ton of silicon and carbon1--materials which1 with the oxygen of the blast1 create a heat which leaves that of the already molten iron far behind4 ,after some time the converter is tipped forward1 and fifteen hundred pounds more of melted iron is added to that already in it4 ,what the temperature of this last is1 may be judged from the fact that though ordinary melted iron is dazzlingly bright1 the melted metal in the converter is so much brighter still1 that the entering stream is dark brown by comparison1 presenting a contrast like that of chocolate poured into a white cup4 ,the contents are now no longer iron1 but liquid steel1 ready for pouring into the caldron2 and1 looking from the front down into the inclined vessel1 we see the almost blindingly bright interior dripping with the drainage of the metal running down its side1 so that the circular mouth1 which is twenty-four inches in diameter1 presents the effect of a disk of molten metal of that size 7were it possible to maintain such a disk in a vertical position74 ,in addition1 we have the actual stream of falling metal1 which continues nearly a minute1 and presents an area of some square feet4 ,the shower of scintillations from this cataract of what seems at first 8sunlike0 brilliancy1 and the area whence such intense heat and light are for a brief time radiated1 make the spectacle a most striking one4 7,see ,fig4 #ef47 ,the 8pour0 is preceded by a shower of sparks1 consisting of little particles of molten steel which are projected fully a hundred feet in the direction of the open mouth of the converter4 ,in the line of this my apparatus was stationed in an open window1 at a point where its view could be directed down into the converter on one side1 and up at the sun on the other4 ,this apparatus consisted of a long photometer-box with a porte-lumire at one end4 ,the mirror of this reflected the sun's rays through the box and then on to the pouring metal1 tracing their way to it by a beam visible in the dusty air 7,fig4 #eg74 ,in the path of this beam was placed the measuring apparatus1 both for heat and light4 ,as the best point of observation was in the line of the blast1 a shower of sparks was driven over the instrument and observer at every 8pour20 and the rain of wet soot from chimneys without1 the bombardment from within1 and the moving masses of red-hot iron around1 made the experiment an altogether peculiar one4 ,the apparatus was arranged in such a way that the effect 7except for the absorption of its beams on the way7 was independent of the size or distance of the sun1 and depended on the absolute radiation there1 and was equivalent1 in fact1 to taking a sample piece of the sun's face of equal size with the fluid metal1 bringing them face to face1 and seeing which was the hotter and brighter4 ,the comparison1 however1 was unfair to the sun1 because its rays were in reality partly absorbed by the atmosphere on the way1 while those of the furnace were not4 ,under these circumstances the heat from any single square foot of the sun's surface was found to be at least eighty-seven times that from a square foot of the melted metal1 while the light from the sun was proved to be1 foot for foot1 over five thousand times that from the molten steel1 though the latter1 separately considered1 seemed to be itself1 as ,i have said1 of quite sunlike brilliancy4 ,illustration3 ,,fig4 #eg4--,,photometer-,,box4 ,we must not conclude from this that the temperature of the sun was five thousand times that of the steel1 but we may be certain that it was at any rate a great deal the higher of the two4 ,it is probable1 from all experiments made up to this date1 that the solar effective temperature is not less than #c1jjj nor more than #cj1jjj degrees of the centigrade thermometer4 ,sir ,william ,siemens1 whose opinion on any question as to heat is entitled to great respect1 thought the lower value nearer the truth1 but this is doubtful4 ,illustration3 ,,fig4 #eh4--,,mouchot',s ,,solar ,,engine4 7,,from ,a ,,french ,,print47 99 99 99 99 99 ,we have1 in all that has preceded1 been speaking of the sun's constitution and appearance1 and have hardly entered on the question of its industrial relations to man4 ,it must be evident1 however1 that if we derive1 as it is asserted we do1 almost all our mechanical power from this solar heat1--if our water-wheel is driven by rivers which the sun feeds by the rain he sucks up for them into the clouds1 if the coal is stored sun-power1 and if1 as ,stevenson said1 it really is the sun which drives our engines1 though at second hand1--there is an immense fund of possible mechanical power still coming to us from him which might be economically utilized4 ,leaving out of sight all our more important relations to him 7for1 as has been already said1 he is in a physical sense our creator1 and he keeps us alive from hour to hour71 and considering him only as a possible servant to grind our corn and spin our flax1 we find that even in this light there are startling possibilities of profit in the study of our subject4 ,from recent measures it appears that from every square yard of the earth exposed perpendicularly to the sun's rays1 in the absence of an absorbing atmosphere1 there could be derived more than one horse-power1 if the heat were all converted into this use1 and that even on such a little area as the island of ,manhattan1 or that occupied by the city of ,london1 the noontide heat is enough1 could it all be utilized1 to drive all the steam-engines in the world4 ,it will not be surprising1 then1 to hear that many practical men are turning their attention to this as a source of power1 and that1 though it has hitherto cost more to utilize the power than it is worth1 there is reason to believe that some of the greatest changes which civilization has to bring may yet be due to such investigations4 ,the visitor to the last ,paris ,exposition may remember an extraordinary machine on the grounds of the ,trocadro1 looking like a gigantic inverted umbrella pointed sunward4 ,this was the sun-machine of ,m4 ,mouchot1 consisting of a great parabolic reflector1 which concentrated the heat on a boiler in the focus and drove a steam-engine with it1 which was employed in turn to work a printing-press1 as our engraving shows 7,fig4 #eh74 ,because these constructions have been hitherto little more than playthings1 we are not to think of them as useless4 ,if toys1 they are the toys of the childhood of a science which is destined to grow1 and in its maturity to apply this solar energy to the use of all mankind4 ,even now they are beginning to pass into the region of practical utility1 and in the form of the latest achievement of ,mr4 ,ericsson's ever-young genius are ready for actual work on an economical scale4 ,we present in ,fig4 #ei his new actually working solar engine1 which there is every reason to believe is more efficient than ,mouchot's1 and probably capable of being used with economical advantage in pumping water in desert regions of our own country4 ,it is pregnant with suggestion of the future1 if we consider the growing demand for power in the world1 and the fact that its stock of coal1 though vast1 is strictly limited1 in the sense that when it is gone we can get absolutely no more4 ,the sun has been making a little every day for millions of years1--so little and for so long1 that it is as though time had daily dropped a single penny into the bank to our credit for untold ages1 until an enormous fund had been thus slowly accumulated in our favor4 ,we are drawing on this fund like a prodigal who thinks his means endless1 but the day will come when our check will no longer be honored1 and what shall we do then8 ,illustration3 ,,fig4 #ei4--;,,ericsson',s ,,new ,,solar ,,engine1 ,,now ,,in ,,practical ,,use ,,in ,,new ,,york4 ,the exhaustion of some of the coal-beds is an affair of the immediate future1 by comparison with the vast period of time we have been speaking of4 ,the ,english coal-beds1 it is asserted1 will1 from present indications1 be quite used up in about three hundred years more4 ,three hundred years ago1 the sun1 looking down on the ,england of our forefathers1 saw a fair land of green woods and quiet waters1 a land unvexed with noisier machinery than the spinning-wheel1 or the needles of the 8free maids that weave their threads with bones40 ,because of the coal which has been dug from its soil1 he sees it now soot-blackened1 furrowed with railway-cuttings1 covered with noisy manufactories1 filled with grimy operatives1 while the island shakes with the throb of coal-driven engines1 and its once quiet waters are churned by the wheels of steamships4 ,many generations of the lives of men have passed to make the ,england of ,elizabeth into the ,england of ,victoria2 but what a moment this time is1 compared with the vast lapse of ages during which the coal was being stored6 ,what a moment in the life of the 8all-beholding sun10 who in a few hundred years--his gift exhausted and the last furnace-fire out--may send his beams through rents in the ivy-grown walls of deserted factories1 upon silent engines brown with rust1 while the mill-hand has gone to other lands1 the rivers are clean again1 the harbors show only white sails1 and ,england's 8black country0 is green once more6 ,to ,america1 too1 such a time may come1 though at a greatly longer distance4 ,does this all seem but the idlest fancy8 ,that something like it will come to pass sooner or later1 is a most certain fact--as certain as any process of ,nature--if we do not find a new source of power2 for of the coal which has supplied us1 after a certain time we can get no more4 ,future ages may see the seat of empire transferred to regions of the earth now barren and desolated under intense solar heat1--countries which1 for that very cause1 will not improbably become the seat of mechanical and thence of political power4 ,whoever finds the way to make industrially useful the vast sun-power now wasted on the deserts of ,north ,africa or the shores of the ,red ,sea1 will effect a greater change in men's affairs than any conqueror in history has done2 for he will once more people those waste places with the life that swarmed there in the best days of ,carthage and of old ,egypt1 but under another civilization1 where man no longer shall worship the sun as a god1 but shall have learned to make it his servant4 ,v4 ,,the ,,planets ,,and ,,the ,,moon4 ,when we look up at the heavens1 we see1 if we watch through the night1 the host of stars rising in the east and passing above us to sink in the west1 always at the same distance and in unchanging order1 each seeming a point of light as feeble as the glow-worm's shine in the meadow over which they are rising1 each flickering as though the evening wind would blow it out4 ,the infant stretches out its hand to grasp the ,pleiades2 but when the child has become an old man the 8seven stars0 are still there unchanged1 dim only in his aged sight1 and proving themselves the enduring substance1 while it is his own life which has gone1 as the shine of the glow-worm in the night4 ,they were there just the same a hundred generations ago1 before the ,pyramids were built2 and they will tremble there still1 when the ,pyramids have been worn down to dust with the blowing of the desert sand against their granite sides4 ,they watched the earth grow fit for man long before man came1 and they will doubtless be shining on when our poor human race itself has disappeared from the surface of this planet4 ,probably there is no one of us who has not felt this solemn sense of their almost infinite duration as compared with his own little portion of time1 and it would be a worthy subject for our thought if we could study them in the light that the ,new ,astronomy sheds for us on their nature4 ,but ,i must here confine myself to the description of but a few of their number1 and speak1 not of the infinite multitude and variety of stars1 each a self-shining sun1 but only of those which move close at hand2 for it is not true of quite all that they keep at the same distance and order4 ,of the whole celestial army which the naked eye watches1 there are five stars which do change their places in the ranks1 and these change in an irregular and capricious manner1 going about among the others1 now forward and now back1 as if lost and wandering through the sky4 ,these wanderers were long since known by distinct names1 as ,mercury1 ,venus1 ,mars1 ,jupiter1 and ,saturn1 and believed to be nearer than the others2 and they are1 in fact1 companions to the earth and fed like it by the warmth of our sun1 and like the moon are visible by the sunlight which they reflect to us4 ,with the earliest use of the telescope1 it was found that while the other stars remained in it mere points of light as before1 these became magnified into disks on which markings were visible1 and the markings have been found with our modern instruments1 in one case at least1 to take the appearance of oceans and snow-capped continents and islands4 ,these1 then1 are not uninhabitable self-shining suns1 but worlds1 vivified from the same fount of energy that supplies us1 and the possible abode of creatures like ourselves4 ,illustration3 ,,fig4 #fj4--,,saturn4 7,,from ,a ,,drawing ,,by ,,trouvelot74 8,properly speaking10 it is said1 8man is the only subject of interest to man20 and if we have cared to study the uninhabitable sun because all that goes on there is found to be so intimately related to us1 it is surely a reasonable curiosity which prompts the question so often heard as to the presence of life on these neighbor worlds1 where it seems at least not impossible that life should exist4 ,even the very little we can say in answer to this question will always be interesting2 but we must regretfully admit at the outset that it is but little1 and that with some planets1 like ,mercury and ,venus1 the great telescopes of modern times cannot do much more than those of ,galileo1 with which our ,new ,astronomy had its beginning4 ,let us leave these1 then1 and pass out to the confines of the planetary system1 where we may employ our telescopes to better advantage4 ,the outer planets1 ,neptune and ,uranus1 remain pale disks in the most powerful instruments1 the first attended by a single moon1 the second by four1 barely visible2 and there is so very little yet known about their physical features1 that we shall do better to give our attention to one of the most interesting objects in the whole heavens1--the planet ,saturn1 on which we can at any rate see enough to arouse a lively curiosity to know more4 ,when ,galileo first turned his glass on ,saturn1 he saw1 as he thought1 that it consisted of three spheres close together1 the middle one being the largest4 ,he was not quite sure of the fact1 and was in a dilemma between his desire to wait longer for further observation1 and his fear that some other observer might announce the discovery if he hesitated4 ,to combine these incompatibilities--to announce it so as to secure the priority1 and yet not announce it till he was ready--might seem to present as great a difficulty as the discovery itself2 but ,galileo solved this1 as we may remember1 by writing it in the sentence1 8,altissimum planetam tergeminum observavi0 78,i have observed the highest planet to be triple071 and then throwing it 7in the printer's phrase7 8into pi10 or jumbling the letters1 which made the sentence into the monstrous word ,,smajsmrmjlmeboetalevmjpvnenvgttavjras1 and publishing this1 which contained his discovery1 but under lock and key4 ,he had reason to congratulate himself on his prudence1 for within two years two of the supposed bodies disappeared1 leaving only one4 ,this was in #afab2 and for nearly fifty years ,saturn continued to all astronomers the enigma which it was to ,galileo1 till in #afef it was finally made clear that it was surrounded by a thin flat ring1 which when seen fully gave rise to the first appearance in ,galileo's small telescope1 and when seen edgewise disappeared from its view altogether4 ,everything in this part of our work depends on the power of the telescope we employ1 and in describing the modern means of observation we pass over two centuries of slow advance1 each decade of which has marked some progress in the instrument1 to one of its completest types1 in the great equatorial at ,washington1 shown in ,fig4 #fa4 ,illustration3 ,,fig4 #fa4--,,the ,,equatorial ,,telescope ,,at ,,washington4 ,the revolving dome above1 the great tube beneath1 its massive piers1 and all its accessories are only means to carry and direct the great lens at the further end1 which acts the part of the lens in our own eye1 and forms the image of the thing to be looked at4 ,galileo's original lens was a single piece of glass1 rather smaller than that of our common spectacles2 but the lens here is composed of two pieces1 each twenty-six inches in diameter1 and collects as much light as a human eye would do if over two feet across4 ,but this is useless if the lens is not shaped with such precision as to send every ray to its proper place at the eye-piece1 nearly thirty-five feet away2 and1 in fact1 the shape given its surface by the skilful hands of the ,messrs4 ,clark1 who made it1 is so exquisitely exact that all the light of a star gathered by this great surface is packed at the distant focus into a circle very much smaller than that made by the dot on this i1 and the same statement may be made of the great ,lick glass1 which is three feet in diameter1--an accuracy we might call incredible were it not certain4 ,it is with instruments of such accuracy that astronomy now works1 and it is with this particular one that some of the observations we are going to describe have been made4 ,in all the heavens there is no more wonderful object than ,saturn1 for it preserves to us an apparent type of the plan on which all the worlds were originally made4 ,let us look at it in this study by ,trouvelot 7,fig4 #fj74 ,the planet1 we must remember1 is a globe nearly seventy thousand miles in diameter1 and the outermost ring is over one hundred and fifty thousand miles across1 so that the proportionate size of our earth would be over-represented here by a pea laid on the engraving4 ,the belts on the globe show delicate tints of brown and blue1 and parts of the ring are1 as a whole1 brighter than the planet2 but this ring1 as the reader may see1 consists of at least three main divisions1 each itself containing separate features4 ,first is the gray outer ring1 then the middle one1 and next the curious 8crape0 ring1 very much darker than the others1 looking like a belt where it crosses the planet1 and apparently feebly transparent1 for the outline of the globe has been seen 7though not very distinctly7 through it4 ,the whole system of rings is of the most amazing thinness1 for it is probably thinner in proportion to its size than the paper on which this is printed is to the width of the page2 and when it is turned edgewise to us1 it disappears to all but the most powerful telescopes1 in which it looks then like the thinnest conceivable line of light1 on which the moons have been seen projected1 appearing like beads sliding along a golden wire4 ,the globe of the planet casts on the ring a shadow1 which is here shown as a broken line1 as though the level of the rings were suddenly disturbed4 ,at other times 7as in a beautiful drawing made with the same instrument by ,professor ,holden7 the line seems continuous1 though curved as though the middle of the ring system were thicker than the edge4 ,the rotation of the ring has been made out by direct observations2 and the whole is in motion about the globe1--a motion so smooth and steady that there is no flickering in the shadow 8where ,saturn's steadfast shade sleeps on its luminous ring40 ,illustration3 ,,fig4 #fb4--;,,jupiter1 ,,moon1 ,,and ,,shadow4 7,,by ,,permission ,,of ,,warren ,,de ,,la ,,rue47 ,what is it8 ,no solid could hold together under such conditions2 we can hardly admit the possibility of its being a liquid film extended in space2 and there are difficulties in admitting it to be gaseous4 ,but if not a solid1 a liquid1 or a gas1 again what can it be8 ,it was suggested nearly two centuries ago that the ring might be composed of innumerable little bodies like meteorites1 circling round the globe so close together as to give the appearance we see1 much as a swarm of bees at a distance looks like a continuous cloud2 and this remains the most plausible solution of what is still in some degree a mystery4 ,whatever it be1 we see in the ring the condition of things which1 according to the nebular hypothesis1 once pertained to all the planets at a certain stage of their formation2 and this1 with the extraordinary lightness of the globe 7for the whole planet would float on water71 makes us look on it as still in the formative stage of uncondensed matter1 where the solid land as yet is not1 and the foot could find no resting-place4 ,astrology figured ,saturn as 8spiteful and cold1--an old man melancholy20 but if we may indulge such a speculation1 modern astronomy rather leads us to think of it as in the infancy of its life1 with every process of planetary growth still in its future1 and separated by an almost unlimited stretch of years from the time when life under the conditions in which we know it can even begin to exist4 99 99 99 99 99 ,like this appears also the condition of ,jupiter 7,fig4 #fb71 the greatest of the planets1 whose globe1 eighty-eight thousand miles in diameter1 turns so rapidly that the centrifugal force causes a visible flattening4 ,the belts which stretch across its disk are of all delicate tints--some pale blue1 some of a crimson lake2 a sea-green patch has been seen1 and at intervals of late years there has been a great oval red spot1 which has now nearly gone1 and which our engraving does not show4 ,the belts are largely1 if not wholly1 formed of rolling clouds1 drifting and changing under our eyes1 though more rarely a feature like the oval spot just mentioned will last for years1 an enduring enigma4 ,the most recent observations tend to make us believe that the equatorial regions of ,jupiter1 like those of the sun1 make more turns in a year than the polar ones2 while the darkening toward the edge is another sunlike feature1 though perhaps due to a distinct cause1 and this is beautifully brought out when any one of the four moons which circle the planet passes between us and its face1 an occurrence also represented in our figure4 ,the moon1 as it steals on the comparatively dark edge1 shows us a little circle of an almost lemon-yellow1 but the effect of contrast grows less as it approaches the centre4 ,next 7or sometimes before71 the disk is invaded by a small and intensely black spot1 the shadow of the moon1 which slides across the planet's face1 the transit lasting long enough for us to see that the whole great globe1 serving as a background for the spectacle1 has visibly revolved on its axis since we began to gaze4 ,photography1 in the skilful hands of the late ,professor ,henry ,draper1 gave us reason to suspect the possibility that a dull light is sent to us from parts of the planet's surface besides what it reflects1 as though it were still feebly glowing like a nearly extinguished sun2 and1 on the whole1 a main interest of these features to us lies in the presumption they create that the giant planet is not yet fit to be the abode of life1 but is more probably in a condition like that of our earth millions of years since1 in a past so remote that geology only infers its existence1 and long before our own race began to be4 ,that science1 indeed1 itself teaches us that such all but infinite periods are needed to prepare a planet for man's abode1 that the entire duration of his race upon it is probably brief in comparison4 99 99 99 99 99 ,we pass by the belt of asteroids1 and over a distance many times greater than that which separates the earth from the sun1 till we approach our own world4 ,here1 close beside it as it were1 in comparison with the enormous spaces which intervene between it and ,saturn and ,jupiter1 we find a planet whose size and features are in striking contrast to those of the great globe we have just quitted4 ,it is ,mars1 which shines so red and looks so large in the sky because it is so near1 but whose diameter is only about half that of our earth4 ,this is indeed properly to be called a neighbor world1 but the planetary spaces are so immense that this neighbor is at closest still about thirty-four million miles away4 ,illustration3 ,,fig #fc4--,,three ,,views ,,of ,,mars4 ,illustration3 ,,fig #fd4--,,map ,,of ,,mars4 ,looking across that great gulf1 we see in our engraving 7,fig4 #fc7--where we have three successive views taken at intervals of a few hours--a globe not marked by the belts of ,jupiter or ,saturn1 but with outlines as of continents and islands1 which pass in turn before our eyes as it revolves in a little over twenty-four and a half of our hours1 while at either pole is a white spot4 ,sir ,william ,herschel was the first to notice that this spot increased in size when it was turned away from the sun1 and diminished when the solar heat fell on it2 so that we have what is almost proof that here is ice 7and consequently water7 on another world4 ,then1 as we study more1 we discern forms which move from day to day on the globe apart from its rotation1 and we recognize in them clouds sweeping over the surface1--not a surface of still other clouds below1 but of what we have good reason to believe to be land and water4 ,by the industry of numerous astronomers1 seizing every favorable opportunity when ,mars comes near1 so many of these features have been gathered that we have been enabled to make fairly complete maps of the planet1 one of which by ,mr4 ,green is here given 7,fig4 #fd74 ,here we see the surface more diversified than that of our earth1 while the oceans are long1 narrow1 canal-like seas1 which everywhere invade the land1 so that on ,mars one could travel almost everywhere by water4 ,these canals seem also in some cases to exist in pairs or to be remarkably duplicated4 ,the spectroscope indicates water-vapor in the ,martial atmosphere1 and some of the continents1 like 8,lockyer ,land10 are sometimes seen white1 as though covered with ice3 while one island 7marked on our map as ,hall ,island7 has been seen so frequently thus1 that it is very probable that here some mountain or tableland rises into the region of perpetual snow4 ,the cause of the red color of ,mars has never been satisfactorily ascertained4 ,its atmosphere does not appear to be dark enough to produce such an effect1 and perhaps as probable an explanation as any is one the suggestion of which is a little startling at first4 ,it is that vegetation on ,mars may be red instead of green6 ,there is no intrinsic improbability in the idea1 for we are even to-day unprepared to say with any certainty why vegetation is green here1 and it is quite easy to conceive of atmospheric conditions which would make red the best absorber of the solar heat4 ,here1 then1 we find a planet on which we obtain many of the conditions of life which we know ourselves1 and here1 if anywhere in the system1 we may allowably inquire for evidence of the presence of something like our own race2 but though we may indulge in supposition1 there is unfortunately no prospect that with any conceivable improvement in our telescopes we shall ever obtain anything like certainty4 ,we cannot assert that there are any bounds to man's invention1 or that science may not1 by some means as unknown to us as the spectroscope was to our grandfathers1 achieve what now seems impossible2 but to our present knowledge no such means exist1 though we are not forbidden to look at the ruddy planet with the feeling that it may hold possibilities more interesting to our humanity than all the wonders of the sun1 and all the uninhabitable immensities of his other worlds4 ,before we leave ,mars1 we may recall to the reader's memory the extraordinary verification of a statement made about it more than a hundred years ago4 ,we shall have for a moment to leave the paths of science for those of pure fiction1 for the words we are going to quote are those of no less a person than our old friend ,captain ,gulliver1 who1 after his adventures with the ,lilliputians1 went to a flying island inhabited largely by astronomers4 ,if the reader will take down his copy of ,swift1 he will find in this voyage of ,gulliver's to ,laputa the following imaginary description of what its imaginary astronomers saw3-- 8,they have likewise discovered two lesser stars or satellites which revolve about ,mars1 whereof the innermost is distant from the centre of the primary planet exactly three of its diameters1 and the outermost five2 the former revolves in the space of ten hours1 and the latter in twenty-one and a half40 ,now1 compare this passage1 which was published in the year #agbg1 with the announcement in the scientific journals of ,august1 #ahgg 7a hundred and fifty years after71 that two moons did exist1 and had just been discovered by ,professor ,hall1 of ,washington1 with the great telescope of which a drawing has been already given4 ,the resemblance does not end even here1 for ,swift was right also in describing them as very near the planet and with very short periods1 the actual distances being about one and a half and seven diameters1 and the actual times about eight and thirty hours respectively1--distances and periods which1 if not exactly those of ,swift's description1 agree with it in being less than any before known in the solar system4 ,it is certain that there could not have been the smallest ground for a suspicion of their existence when 8,gulliver's ,travels0 was written1 and the coincidence--which is a pure coincidence--certainly approaches the miraculous4 ,we can no longer1 then1 properly speak of 8the snowy poles of moonless ,mars10 though it does still remain moonless to all but the most powerful telescopes in the world1 for these bodies are the very smallest known in the system4 ,they present no visible disks to measure1 but look like the faintest of points of light1 and their size is only to be guessed at from their brightness4 ,professor ,pickering has carried on an interesting investigation of them4 ,his method depended in part on getting holes of such smallness made in a plate of metal that the light coming through them would be comparable with that of the ,martial moons in the telescope4 ,it was found almost impossible to command the skill to make these holes small enough1 though one of the artists employed had already distinguished himself by drilling a hole through a fine cambric needle lengthwise1 so as to make a tiny steel tube of it4 ,when the difficulty was at last overcome1 the satellites were found to be less than ten miles in diameter1 and a just impression both of their apparent size and light may be gathered from the statement that either roughly corresponds to that which would be given by a human hand held up at ,washington1 and viewed from ,boston1 ,massachusetts1 a distance of four hundred miles4 ,we approach now the only planet in which man is certainly known to exist1 and which ought to have an interest for us superior to any which we have yet seen1 for it is our own4 ,we are voyagers on it through space1 it has been said1 as passengers on a ship1 and many of us have never thought of any part of the vessel but the cabin where we are quartered4 ,some curious passengers 7these are the geographers7 have visited the steerage1 and some 7the geologists7 have looked under the hatches1 and yet it remains true that those in one part of our vessel know little1 even now1 of their fellow-voyagers in another4 ,how much less1 then1 do most of us know of the ship itself1 for we were all born on it1 and have never once been off it to view it from the outside6 ,no world comes so near us in the aerial ocean as the moon2 and if we desire to view our own earth as a planet1 we may put ourselves in fancy in the place of a lunar observer4 8,is it inhabited80 would probably be one of the first questions which he would ask1 if he had the same interest in us that we have in him2 and the answer to this would call out all the powers of the best telescopes such as we possess4 ,an old author1 ,fontenelle1 has put in the mouth of an imaginary spectator a lively description of what would be visible in twenty-four hours to one looking down on the earth as it turned round beneath him4 8,i see passing under my eyes10 he says1 8all sorts of faces1--white and black and olive and brown4 ,now it's hats1 and now turbans1 now long locks and then shaven crowns2 now come cities with steeples1 next more with tall1 crescent-capped minarets1 then others with porcelain towers2 now great desolate lands1 now great oceans1 then dreadful deserts1--in short1 all the infinite variety the earth's surface bears40 ,the truth is1 however1 that1 looking at the earth from the moon1 the largest moving animal1 the whale or the elephant1 would be utterly beyond our ken2 and it is questionable whether the largest ship on the ocean would be visible1 for the popular idea as to the magnifying power of great telescopes is exaggerated4 ,it is probable that under any but extraordinary circumstances our lunar observer1 with our best telescopes1 could not bring the earth within less than an apparent distance of five hundred miles2 and the reader may judge how large a moving object must be to be seen1 much less recognized1 by the naked eye at such a distance4 ,of course1 a chief interest of the supposition we are making lies in the fact that it will give us a measure of our own ability to discover evidences of life in the moon1 if there are any such as exist here2 and in this point of view it is worth while to repeat1 that scarcely any temporary phenomenon due to human action could be even telescopically visible from the moon under the most favoring circumstances4 ,an army such as ,napoleon led to ,russia might conceivably be visible if it moved in a dark solid column across the snow4 ,it is barely possible that such a vessel as one of the largest ocean steamships might be seen1 under very favorable circumstances1 as a moving dot2 and it is even quite probable that such a conflagration as the great fire of ,chicago would be visible in the lunar telescope1 as something like a reddish star on the night side of our planet2 but this is all in this sort that could be discerned4 ,by making minute maps1 or1 still better1 photographs1 and comparing one year with another1 much however might have been done by our lunar observer during this century4 ,in its beginning1 in comparison to the vast forests which then covered the ,north ,american continent1 the cultivated fields along its eastern seaboard would have looked to him like a golden fringe bordering a broad mantle of green2 but now he would see that the golden fringe has encroached upon the green farther back than the ,mississippi1 and he would gather his best evidence of change from the fact 7surely a noteworthy one7 that the people of the ,united ,states have altered the features of the world during the present century to a degree visible in another planet6 ,our observer would probably be struck by the moving panorama of forests1 lakes1 continents1 islands1 and oceans1 successively gliding through the field of view of his telescope as the earth revolved2 but1 travelling along beside it on his lunar station1 he would hardly appreciate its actual flight through space1 which is an easy thing to describe in figures1 and a hard one to conceive4 ,if we look up at the clock1 and as we watch the pendulum recall that we have moved about nineteen miles at every beat1 or in less than three minutes1 over a distance greater than that which divides ,new ,york from ,liverpool1 we still probably but very imperfectly realize the fact that 7dropping all metaphor7 the earth is really a great projectile1 heavier than the heaviest of her surface rocks1 and traversing space with a velocity of over sixty times that of the cannon-ball4 ,even the firing of a great gun with a ball weighing one or two hundred pounds is1 to the novice at least1 a striking spectacle4 ,the massive iron sphere is hoisted into the gun1 the discharge comes1 the ground trembles1 and1 as it seems1 almost in the same instant1 a jet rises where the ball has touched the water far away4 ,the impression of immense velocity and of a resistless capacity of destruction in that flying mass is irresistible1 and justifiable too3 but what is this ball to that of the earth1 which is a globe counting eight thousand miles in diameter1 and weighing about six thousand millions of millions of millions of tons2 which1 if our cannon-ball were flying ahead a mile in advance of its track1 would overtake it in less than the tenth part of a second2 and which carries such a potency of latent destruction and death in this motion1 that if it were possible instantly to arrest it1 then1 in that instant1 8earth and all which it inherits would dissolve0 and pass away in vapor8 ,our turning sphere is moving through what seems to be all but an infinite void1 peopled only by wandering meteorites1 and where warmth from any other source than the sun can scarcely be said to exist2 for it is important to observe that whether the interior be molten or not1 we get next to no heat from it4 ,the cold of outer space can only be estimated in view of recent observations as at least four hundred degrees ,fahrenheit below zero 7mercury freezes at thirty-nine degrees below71 and it is the sun which makes up the difference of all these lacking hundreds of degrees to us1 but indirectly1 and not in the way that we might naturally think1 and have till very lately thought2 for our atmosphere has a great deal to do with it beside the direct solar rays1 allowing more to come in than to go out1 until the temperature rises very much higher than it would were there no air here4 ,thus1 since it is this power in the atmosphere of storing the heat which makes us live1 no less than the sun's rays themselves1 we see how the temperature of a planet may depend on considerations quite beside its distance from the sun2 and when we discuss the possibility of life in other worlds1 we shall do well to remember that ,saturn may be possibly a warm world1 and ,mercury conceivably a cold one4 ,we used to be told that this atmosphere extended forty-five miles above us1 but later observation proves its existence at a height of many times this2 and a remarkable speculation1 which ,dr4 ,hunt strengthens with the great name of ,newton1 even contemplates it as extending in ever-increasing tenuity until it touches and merges in the atmosphere of other worlds4 ,illustration3 ,,fig4 #fe4--,,the ,,moon4 7,,from ,a ,,photograph ,,by ,l4 ,m4 ,,rutherfurd1 #ahgc1 ,,published ,,by ,o4 ,g4 ,,mason47 ,but if we begin to talk of things new and old which interest us in our earth as a planet1 it is hard to make an end4 ,still we may observe that it is the very familiarity of some of these which hinders us from seeing them as the wonders they really are4 ,how has this familiarity1 for instance1 made commonplace to us not only the wonderful fact that the fields and forests1 and the apparently endless plain of earth and ocean1 are really parts of a great globe which is turning round 7for this rotation we all are familiar with71 but the less appreciated miracle that we are all being hurled through space with an immensely greater speed than that of the rotation itself4 ,it needs the vision of a poet to see this daily miracle with new eyes2 and a great poet has described it for us1 in words which may vivify our scientific conception4 ,let us recall the prologue to 8,faust10 where the archangels are praising the works of the ,lord1 and looking at the earth1 not as we see it1 but down on it1 from heaven1 as it passes by1 and notice that it is precisely this miraculous swiftness1 so insensible to us1 which calls out an angel's wonder4 8,and swift and swift beyond conceiving ,the splendor of the world goes round1 ,day's ,eden-brightness still relieving ,the awful ,night's intense profound4 ,the ocean tides in foam are breaking1 ,against the rocks' deep bases hurled1 ,and both1 the spheric race partaking1 ,eternal1 swift1 are onward whirled40#e #e ,bayard ,taylor's translation4 ,so1 indeed1 might an angel see it and describe it6 99 99 99 99 99 ,we may have been already led to infer that there is a kind of evolution in the planets' life1 which we may compare1 by a not wholly fanciful analogy1 to ours2 for we have seen worlds growing into conditions which may fit them for habitability1 and again other worlds where we may surmise1 or may know1 that life has come4 ,to learn of at least one which has completed the analogy1 by passing beyond this term to that where all life has ceased1 we need only look on the moon4 99 99 99 99 99 ,the study of the moon's surface has been continued now from the time of ,galileo1 and of late years a whole class of competent observers has been devoted to it1 so that astronomers engaged in other branches have oftener looked on this as a field for occasional hours of recreation with the telescope than made it a constant study4 ,i can recall one or two such hours in earlier observing days1 when1 seated alone under the overarching iron dome1 the world below shut out1 and the world above opened1 the silence disturbed by no sound but the beating of the equatorial clock1 and the great telescope itself directed to some hill or valley of the moon1 ,i have been so lost in gazing that it seemed as though a look through this1 the real magic tube1 had indeed transported me to the surface of that strange alien world4 ,fortunately for us1 the same spectacle has impressed others with more time to devote to it and more ability to render it1 so that we not only have most elaborate maps of the moon for the professional astronomer1 but abundance of paintings1 drawings1 and models1 which reproduce the appearance of its surface as seen in powerful telescopes4 ,none of the latter class deserves more attention than the beautiful studies of ,messrs4 ,nasmyth and ,carpenter1 who prepared at great labor very elaborate and1 in general1 very faithful models of parts of its surface1 and then had them photographed under the same illumination which fell on the original2 and ,i wish to acknowledge here the special indebtedness of this part of what ,i have to lay before the reader to their work1 from which the following illustrations are chiefly taken4 ,let us remember that the moon is a little over twenty-one hundred miles in diameter2 that it weighs1 bulk for bulk1 about two-thirds what the earth does1 so that1 in consequence of this and its smaller size1 its total weight is only about one-eightieth of that of our globe2 and that1 the force of gravity at its surface being only one-sixth what it is here1 eruptive explosions can send their products higher than in our volcanoes4 ,its area is between four and five times that of the ,united ,states1 and its average distance is a little less than two hundred and forty thousand miles4 ,illustration3 ,,fig4 #ff4--,,the ,,full ,,moon4 ,this is very little in comparison with the great spaces we have been traversing in imagination2 but it is absolutely very large1 and across it the valleys and mountains of this our nearest neighbor disappear1 and present to the naked eye only the vague lights and shades known to us from childhood as 8the man in the moon10 and which were the puzzle of the ancient philosophers1 who often explained them as reflections of the earth itself1 sent back to us from the moon as from a mirror4 ,it1 at any rate1 shows that the moon always turns the same face toward us1 since we always see the same 8man10 and that there must be a back to the moon which we never behold at all2 and1 in fact1 nearly half of this planet does remain forever hidden from human observation4 ,the 8man in the moon0 disappears when we are looking in a telescope1 because we are then brought so near to details that the general features are lost2 but he can be seen in any photograph of the full moon by viewing it at a sufficient distance1 and making allowance for the fact that the contrasts of light and shade appear stronger in the photograph than they are in reality4 ,if the small full moon given in ,fig4 #ff1 for instance1 be looked at from across a room1 the naked-eye view will be recovered1 and its connection with the telescopic ones better made out4 ,the best time for viewing the moon1 however1 is not at the full1 but at the close of the first quarter2 for then we see1 as in this beautiful photograph 7,fig4 #fe7 by ,mr4 ,rutherfurd1 that the sunlight1 falling slantingly on it1 casts shadows which bring out all the details so that we can distinguish many of them even here1--this photograph1 though much reduced1 giving the reader a better view than ,galileo obtained with his most powerful telescope4 ,the large gray expanse in the lower part is the ,mare ,serenitatis1 that on the left the ,mare ,crisium1 and so on2 these 8seas10 as they were called by the old observers1 being no seas at all in reality1 but extended plains which reflect less light than other portions1 and which with higher powers show an irregular surface4 ,most of the names of the main features of the lunar surface were bestowed by the earlier observers in the infancy of the telescope1 when her orb 8,through optic glass the ,tuscan artist #8viewed' ,at evening from the top of ,fiesole ,or in ,valdarno1 to descry new lands1 ,rivers1 or mountains in her spotty globe40 ,mountains there are1 like the chain of the lunar ,apennines1 which the reader sees a little below the middle of the moon1 and to the right of the ,mare ,serenitatis1 and where a good telescope will show several thousand distinct summits4 ,apart from the mountain chains1 however1 the whole surface is visibly pitted with shallow1 crater-like cavities1 which vary from over a hundred miles in diameter to a few hundred yards or less1 and which1 we shall see later1 are smaller sunken plains walled about with mountains or hills4 ,one of the most remarkable1 of these is ,tycho1 here seen on the photograph of the full moon 7,fig4 #ff71 from which radiating streaks go in all directions over the lunar surface4 ,these streaks are a feature peculiar to the moon 7at least we know of nothing to which they can be compared on the earth71 for they run through mountain and valley for hundreds of miles without any apparent reference to the obstacles in their way1 and it is clear that the cause is a deep-seated one4 ,this cause is believed by our authors to be the fact that the moon was once a liquid sphere over which a hard crust formed1 and that in subsequent time the expansion of the interior before solidification cracked the shell as we see4 ,the annexed figure 7,fig4 #fg7 is furnished by them to illustrate their theory1 and to show the effects of what they believe to be an analogous experiment1 in minimis1 to what ,nature has performed on the grandest scale2 for the photograph shows a glass globe actually cracked by the expansion of an enclosed fluid 7in this case water71 and the resemblance of the model to the photograph of the full moon on page #ada is certainly a very interesting one4 ,illustration3 ,,fig4 #fg4--;,,glass ,,globe1 ,,cracked4 ,we are able to see from this1 and from the multitude of craters shown even on the general view1 where the whole face of our satellite is pit-marked1 that eruptive action has been more prominent on the moon in ages past than on our own planet1 and we are partly prepared for what we see when we begin to study it in detail4 ,we may select almost any part of the moon's surface for this nearer view1 with the certainty of finding something interesting4 ,let us choose1 for instance1 on the photograph of the half-full moon 7,fig4 #fe71 the point near the lower part of the ,terminator 7as the line dividing light from darkness is called7 where a minute sickle of light seems to invade the darkness1 and let us apply in imagination the power of a large telescope to it4 ,we are brought at once considerably within a thousand miles of the surface1 over which we seem to be suspended1 everything lying directly beneath us as in a bird's-eye view1 and what we see is the remarkable scene shown in ,fig4 #fh4 ,we have before us such a wealth of detail that the only trouble is to choose what to speak of where every point has something to demand attention1 and we can only give here the briefest reference to the principal features4 ,the most prominent of these is the great crater 8,plato10 which lies in the lower right-hand part of the cut4 ,it will give the reader an idea of the scale of things to state that the diameter of its ring is about seventy miles2 so that he will readily understand that the mountains surrounding it may average five to six thousand feet in height1 as they do4 ,the sun is shining from the left1 and1 being low1 casts long shadows1 so that the real forms of the mountains on one side are beautifully indicated by these shadows1 where they fall on the floor of the crater4 ,in the lower part of the mountain wall there has been a land-slide1 as we see by the fragments that have rolled down into the plain1 and of which a trace can be observed in our engraving4 ,the whole is quite unlike most terrestrial craters1 however1 not only in its enormous size1 but in its proportions2 for the floor is not precipitous1 but flat1 or partaking of the general curvature of the lunar surface1 which it sinks but little below4 ,i have watched with interest in the telescope streaks and shades on the floor of ,plato1 not shown in our cut2 for here some have suspected evidences of change1 and fancied a faint greenish tint1 as if due to vegetation1 but it is probably fancy only4 ,notice the number of small craters around the big one1 and everywhere on the plate1 and then look at the amazingly rugged and tumbled mountain heaps on the left 7the lunar ,alps71 cut directly through by a great valley 7the valley of the ,alps71 which is at the bottom about six miles wide and extraordinarily flat1--flatter and smoother even than our engraving shows it1 and looking as though a great engineering work1 rather than an operation of ,nature1 were in question4 ,above this the mountain shadows are cast upon a wide plain1 in which are both depressed pits with little mountain 7or rather hill7 rings about them1 and extraordinary peaks1 one of which1 ,pico 7above the great crater71 starts up abruptly to the height of eight thousand feet1 a lunar ,matterhorn4 ,if ,mars were as near as the moon1 we should see with the naked eye clouds passing over its face2 and that we never do see these on the moon1 even with the telescope1 is itself a proof that none exist there4 ,now1 this absence of clouds1 or indeed of any evidence of moisture1 is confirmed by every one of the nearer views like those we are here getting4 ,we might return to this region with the telescope every month of our lives without finding one indication of vapor1 of moisture1 or even of air2 and from a summit like ,pico1 could we ascend it1 we should look out on a scene of such absolute desolation as probably no earthly view could parallel4 ,if1 as is conceivable1 these plains were once covered with verdure1 and the abode of living creatures1 verdure and life exist here no longer1 and over all must be the silence of universal death4 ,but we must leave it for another scene4 ,illustration3 ,,fig4 #fh4--,,plato ,,and ,,the ,,lunar ,,alps4 ,south of ,plato extends for many hundred miles a great plain1 which from its smoothness was thought by the ancient observers to be water1 and was named by them the 8,imbrian ,sea10 and this is bounded on the south and west by a range of mountains--the 8lunar ,apennines0 7,fig4 #fi7--which are the most striking on our satellite4 ,they are visible even with a spy-glass1 looking then like bread-crumbs ranged upon a cloth1 while with a greater power they grow larger and at the same time more chaotic4 ,as we approach nearer1 we see that they rise with a comparatively gradual slope1 to fall abruptly1 in a chain of precipices that may well be called tremendous1 down to the plain below1 across which their shadows are cast4 ,near their bases are some great craters of a somewhat different type from ,plato1 and our illustration represents an enlarged view of a part of this ,apennine chain1 of the great crater ,archimedes1 and of its companions ,aristillus and ,autolycus4 ,our engraving will tell1 more than any description1 of the contrast of the tumbled mountain peaks with the level plain from which they spring1--a contrast for which we have scarcely a terrestrial parallel1 though the rise of the ,alps from the plains of ,lombardy may suggest an inadequate one4 ,the ,sierra ,nevadas of ,california climb slowly up from the coast side1 to descend in great precipices on the east1 somewhat like this2 but the country at their feet is irregular and broken1 and their highest summits do not equal those before us1 which rise to seventeen or eighteen thousand feet1 and from one of which we should look out over such a scene of desolation as we can only imperfectly picture to ourselves from any experience of a terrestrial desert4 ,the curvature of the moon's surface is so much greater than ours1 that it would hide the spurs of hills which buttress the southern slopes of ,archimedes1 leaving only the walls of the great mountain ring visible in the extremest horizon1 while between us and them would extend what some still maintain to have been the bed of an ancient lunar ocean1 though assuredly no water exists there now4 ,among the many fanciful theories to account for the forms of the ringed plains1 one 7and this is from a man of science whose ideas are always original7 invokes the presence of water4 ,according to it1 these great plains were once ocean beds1 and in them worked a coral insect1 building up lunar 8atolls0 and ring-shaped submarine mountains1 as the coral polyp does here4 ,the highest summits of the great rings thus formed were then low islands1 just 8a-wash0 with the waves of the ancient lunar sea1 and1 for aught we know1 green with feathery palms4 ,then came 7in the supposition in question7 a time when the ocean dried up1 and the mountains were left standing1 as we see1 in rings1 after the cause of their formation was gone4 ,if it be asked where the water went to1 the answer is not very obvious on the old theories2 but those who believe in them point to the extraordinary cracks in the soil1 like those our engraving shows1 as chasms and rents1 by which the vanished seas1 and perhaps also the vanished air1 have been absorbed into the interior4 ,illustration3 ,,fig4 #fi4--,,the ,,lunar ,,apennines3 ,,archimedes4 ,if there was indeed such an ancient ocean1 it would have washed the very feet of the precipices on whose summits we are in imagination standing1 and below us their recesses would have formed harbors which fancy might fill with commerce1 and cities in which we might picture life and movement where all is now dead4 ,it need hardly be said that no telescope has ever revealed their existence 7if such ruins1 indeed1 there are71 and it may be added that the opinion of geologists is1 as a whole1 unfavorable to the presence of water on the moon1 even in the past1 from the absence of any clear evidence of erosive action2 but perhaps we are not yet entitled to speak on these points with certainty1 and are not forbidden to believe that water may have existed here in the past by any absolute testimony to the contrary4 ,the views of those who hold the larger portion of the lunar craters to have been volcanic in their formation are far more probable2 and perhaps as simple an evidence of the presumption in their favor as we can give is directly to compare such a lunar region as this1 the picture of which was made for us from a model1 with a similar model made from some terrestrial volcanic region4 ,here 7,fig4 #gj7 is a photograph of such a modelled plan of the country round the ,bay of ,naples1 showing the ancient crater of ,vesuvius and its central cone1 with other and smaller craters along the sea4 ,here1 of course1 we know that the forms originated in volcanic action1 and a comparison of them with our moon-drawing is most interesting4 ,to return to our ,apennine region 7,fig4 #fi71 we must admit1 however1 when we consider the vast size of these things 7,archimedes is fifty miles in diameter71 that they are very different in proportion from our terrestrial craters1 and that numbers of them present no central cone whatever2 so that if some of them seem clearly eruptive1 there are others to which we have great difficulties in making these volcanic theories apply4 ,let us look1 for instance1 at still another region 7,fig4 #ga74 ,it lies rather above the centre of the full moon1 and may be recognized also on the ,rutherfurd photograph2 and it consists of the group of great ring-plains1 three of which form prominent figures in our cut4 ,ptolemy 7the lower of these in the drawing7 is an example of such a plain1 whose diameter reaches to about one hundred and fifteen miles1 so that it encloses an area of nearly eight thousand square miles 7or about that of the ,state of ,massachusetts71 within which there is no central cone or point from which eruptive forces appear to have acted1 except the smaller craters it encloses4 ,on the south we see a pass in the mountain wall opening into the neighboring ring-plain of ,alphonsus1 which is only less in size2 and south of this again is ,arzachel1 sixty-six miles in diameter1 surrounded with terraced walls1 rising in one place to a height greater than that of ,mont ,blanc1 while the central cone is far lower4 ,the whole of the region round about1 though not the roughest on the moon1 is rough and broken in a way beyond any parallel here1 and which may speak for itself2 but perhaps the most striking of the many curious features--at least the only one we can pause to examine--is what is called 8,the ,railway10 an almost perfectly straight line1 on one side of which the ground has abruptly sunk1 leaving the undisturbed part standing like a wall1 and forming a 8fault10 as geologists call it4 ,this is the most conspicuous example of its kind in the moon1 but it is only one of many evidences that we are looking at a world whose geological history has been not wholly unlike our own4 ,but the moon contains1 as has been said1 but the one-eightieth part of the mass of our globe1 and has therefore cooled with much greater rapidity1 so that it has not only gone through the epochs of our own past time1 but has in all probability already undergone experiences which for us lie far in the future2 and it is hardly less than justifiable language to say that we are beholding here in some respects what the face of our world may be when ages have passed away4 ,illustration3 ,,fig4 #gj4--,,vesuvius ,,and ,,neighborhood ,,of ,,naples4 ,to see this more clearly1 we may consider that in general we find that the early stages of cosmical life are characterized by great heat2 a remark of the truth of which the sun itself furnishes the first and most obvious illustration4 ,then come periods which we appear to have seen exemplified in ,jupiter1 where the planet is surrounded by volumes of steam-like vapor1 through which we may almost believe we recognize the dull glow of not yet extinguished fires2 then times like those which our earth passed through before it became the abode of man2 and then the times in which human history begins4 ,but if this process of the gradual loss of heat go on indefinitely1 we must yet come to still another era1 when the planet has grown too cold to support life1 as it was before too hot2 and this condition1 in the light of some very recent investigations1 it seems probable we have now before us on the moon4 ,we have1 it is true1 been taught until very lately that the side of the moon turned sunward would grow hotter and hotter in the long lunar day1 till it reached a temperature of two hundred to three hundred degrees ,fahrenheit1 and that in the equally long lunar night it would fall as much as this below zero4 ,but the evidence which was supposed to support this conclusion as to the heat of the lunar day is not supported by recent experiments of the writer2 and if these be trustworthy1 certain facts appear to him to show that the temperature of the moon's surface1 even under full perpetual sunshine1 must be low1--and this because of the absence of air there to keep the stored sun-heat from being radiated away again into space4 ,as we ascend the highest terrestrial mountains1 and get partly above our own protecting blanket of air1 things do not grow hotter and hotter1 but colder and colder2 and it seems contrary to the teachings of common sense to believe that if we could ascend higher yet1 where the air ceases altogether1 we should not find that it grew colder still4 ,but this last condition 7of airlessness7 is the one which does prevail beyond a doubt in the moon1 on whose whole surface1 then1 there must be 7unless there are sources of internal heat of which we know nothing7 conditions of temperature which are an exaggeration of those we experience on the summit of a very lofty mountain1 where we have the curious result that the skin may be burned under the solar rays1 while we are shivering at the same time in what the thermometer shows is an arctic cold4 ,we have heard of this often2 but a personal experience so impressed the fact on me that ,i will relate it for the benefit of the reader1 who may wish to realize to himself the actual conditions which probably exist in the airless lunar mountains and plains we are looking at4 ,he cannot go there2 but he may go if he pleases1 as ,i have done1 to the waterless1 shadeless waste which stretches at the eastern slope of the ,sierra ,nevadas 7a chain almost as high and steep as the lunar ,apennines71 and live some part of ,july and ,august in this desert1 where the thermometer rises occasionally to one hundred and ten degrees in the shade1 and his face is tanned till it can tan no more1 and he appears to himself to have experienced the utmost in this way that the sun can do4 ,the sky is cloudless1 and the air so clear that all idea of the real distance and size of things is lost4 ,the mountains1 which rise in tremendous precipices above him1 seem like moss-covered rocks close at hand1 on the tops of which1 here and there1 a white cloth has been dropped2 but the 8moss0 is great primeval forests1 and the white cloths large isolated snow-fields1 tantalizing the dweller in the burning desert with their delusive nearness4 ,when ,i climbed the mountains1 at an altitude of ten thousand feet ,i already found the coolness delicious1 but at the same time 7by the strange effect ,i have been speaking of7 the skin began to burn1 as though the seasoning in the desert counted for nothing at all2 and as the air grew thinner and thinner while ,i mounted still higher and higher1 though the thermometer fell1 every part of the person exposed to the solar rays presented the appearance of a recent severe burn from an actual fire1--and a really severe burn it was1 as ,i can testify1--and yet all the while around us1 under this burning sun and cloudless sky1 reigned a perpetual winter which made it hard to believe that torrid summer still lay below4 ,the thinner the air1 then1 the colder it grows1 even where we are exposed to the sun1 and the lower becomes the reading of the thermometer4 ,now1 by means of suitable apparatus1 it was sought by the writer to determine1 while at this elevation of fifteen thousand feet1 how great the fall of temperature would be if the thin air there could be removed altogether2 and the result was that the thermometer would under such circumstances fall1 at any rate1 below zero in the full sunshine4 ,illustration3 ,,fig4 #ga4--,,ptolemy ,,and ,,arzachel4 ,of course1 all this applies indirectly to the moon1 above whose surface 7if these inferences be correct7 the mercury in the bulb of a thermometer would probably freeze and never melt again during the lunar day 7and still less during the lunar night71--a conclusion which has been reached through other means by ,mr4 ,ericsson1--and whose surface itself cannot be very greatly warmer4 ,other and direct measures of the lunar heat are still in progress while this is being written1 but their probable result seems to be already indicated3 it is that the moon's surface1 even in perpetual sunshine1 must be forever cold4 ,just how cold1 is still doubtful2 and it is not yet certain whether ice1 if once formed there1 could ever melt4 ,here 7,fig4 #gb7 is one more scene from the almost unlimited field the lunar surface affords4 ,the most prominent things in the landscape before us are two fine craters 7,mercator and ,campanus71 each over thirty miles in diameter2 but we have chosen this scene for remark rather on account of the great crack or rift which is seen in the upper part1 and which cuts through plain and mountain for a length of sixty miles4 ,such cracks are counted by hundreds on the moon1 where they are to be seen almost everywhere2 and other varieties1 in fact1 are visible on this same plate1 but we will not stop to describe them4 ,this one varies in width from an eighth of a mile to a mile2 and though we cannot see to the bottom of it1 others are known to be at least eight miles deep1 and may be indefinitely deeper4 ,the edge of a cliff on the earth commonly gets weather-worn and rounded2 but here the edge is sharp1 so that a traveller along the lunar plains would come to the very brink of this tremendous chasm before he had any warning of its existence4 ,it is usually thus with all such rifts2 and the straightness and sharpness of the edge in these cases suggest the appearance of an ice-crack to the observer4 ,i do not mean to assert that there is more than a superficial resemblance4 ,i do not write as a geologist2 but in view of what we have just been reading of the lunar cold1 we may ask ourselves whether1 if water ever did exist here1 we should not expect to find perpetual ice1 not necessarily glittering1 but covered1 perhaps1 with the deposits of an air laden with the dust-products of later volcanic eruptions1 or even covered in after ages1 when the air has ceased from the moon1 with the slow deposit of meteoric dust during millions of years of windless calm4 ,what else can we think will become of the water on our own earth if it be destined to pass through such an experience as we seem to see prophesied in the condition of our dead satellite8 ,the reader must not understand me as saying that there is ice on the moon1--only that there is not improbably perpetual ice there now if there ever was water in past time2 and he is not to suppose that to say this is in any way to deny what seems the strong evidence of the existence of volcanic action everywhere1 for the two things may well have existed in successive ages of our satellite's past1 or even have both existed together1 like ,hecla1 within our own arctic snows2 and if no sign of any still active lunar volcano has been discovered1 we appear to read the traces of their presence in the past none the less clearly4 ,i remember that at one time1 when living on the lonely upper lava-wastes of ,mount ,etna1 which are pitted with little craters1 ,i grew acquainted with so many a chasm and rent filled with these1 that the dreary landscape appeared from above as if a bit of the surface of the moon ,i looked up at through the telescope had been brought down beside me4 ,illustration3 ,,fig4 #gb4--,,mercator ,,and ,,campanus4 ,i remember1 too1 that as ,i studied the sun there1 and watched the volcanic outbursts on its surface1 ,i felt that ,i possibly embraced in a threefold picture as many stages in the history of planetary existence1 through all of which this eruptive action was an agent1--above in the primal energies of the sun2 all around me in the great volcano1 black and torn with the fires that still burn below1 and whose smoke rose over me in the plume that floated high up from the central cone2 and finally in this last stage in the moon1 which hung there pale in the daylight sky1 and across whose face the vapors of the great terrestrial volcano drifted1 but on whose own surface the last fire was extinct4 ,we shall not get an adequate idea of it all1 unless we add to our bird's-eye views one showing a chain of lunar mountains as they would appear to us if we saw them1 as we do our own ,alps or ,apennines1 from about their feet2 and such a view ,fig4 #gd affords us4 ,in the barren plain on the foreground are great rifts such as we have been looking at from above1 and smaller craters1 with their extinct cones2 while beyond rise the mountains1 ghastly white in the cold sunshine1 their precipices crowned by no mountain fir or cedar1 and softened by no intervening air to veil their nakedness4 ,if the reader has ever climbed one of the highest ,alpine peaks1 like those about ,monte ,rosa or the ,matterhorn1 and there waited for the dawn1 he cannot but remember the sense of desolation and strangeness due to the utter absence of everything belonging to man or his works or his customary abode1 above all which he is lifted into an upper world1 so novel and1 as it were1 so unhuman in its features1 that he is not likely to have forgotten his first impression of it2 and this impression gives the nearest but still a feeble idea of what we see with the telescope in looking down on such a colorless scene1 where too no water bubbles1 no tree can sigh in the breeze1 no bird can sing1--the home of silence4 ,illustration3 ,,fig4 #gc4--,,withered ,,hand4 ,but here1 above it1 hangs a world in the sky1 which we should need to call in color to depict1 for it is green and yellow with the forests and the harvest-fields that overspread its continents1 with emerald islands studding its gray oceans1 over all of which sweep the clouds that bring the life-giving rain4 ,it is our own world1 which lights up the dreary lunar night1 as the moon does ours4 ,illustration3 ,,fig4 #gd4--;,,ideal ,,lunar ,,landscape ,,and ,,earth-,,shine4 ,the signs of age are on the moon4 ,it seems pitted1 torn1 and rent by the past action of long-dead fires1 till its surface is like a piece of porous cinder under the magnifying-glass1--a burnt-out cinder of a planet1 which rolls through the void like a ruin of what has been2 and1 more significant still1 this surface is wrinkled everywhere1 till the analogy with an old and shrivelled face or hand or fruit 7,figs4 #gc and #ge71 where the puckered skin is folded about a shrunken centre1 forces itself on our attention1 and suggests a common cause1--a something underlying the analogy1 and making it more than a mere resemblance4 ,illustration3 ,,fig4 #ge4--,,withered ,,apple4 ,the moon1 then1 is dead2 and if it ever was the home of a race like ours1 that race is dead too4 ,i have said that our ,new ,astronomy modifies our view of the moral universe as well as of the physical one2 nor do we need a more pregnant instance than in this before us4 ,in these days of decay of old creeds of the eternal1 it has been sought to satisfy man's yearning toward it by founding a new religion whose god is ,humanity1 and whose hope lies in the future existence of our own race1 in whose collective being the individual who must die may fancy his aims and purpose perpetuated in an endless progress4 ,but1 alas for hopes looking to this alone6 we are here brought to face the solemn thought that1 like the individual1 though at a little further date1 ,humanity itself may die6 ,before we leave this dead world1 let us take a last glance at one of its fairest scenes1--that which we obtain when looking at a portion on which the sun is rising1 as in this view of ,gassendi 7,fig4 #gf71 in which the dark part on our right is still the body of the moon1 on which the sun has not yet risen4 ,its nearly level rays stretch elsewhere over a surface that is1 in places1 of a strangely smooth texture1 contrasting with the ruggedness of the ordinary soil1 which is here gathered into low plaits1 that1 with the texture we have spoken of1 look 8,like marrowy crapes of ,china silk1 ,or wrinkled skin on scalded milk10 as they lie1 soft and almost beautiful1 in the growing light4 ,where its first beams are kindling1 the summits cast their shadows illimitedly over the darkening plains away on the right1 until they melt away into the night1--a night which is not utterly black1 for even here a subdued radiance comes from the earth-shine of our own world in the sky4 ,let us leave here the desolation about us1 happy that we can come back at will to that world1 our own familiar dwelling1 where the meadows are still green and the birds still sing1 and where1 better yet1 still dwells our own kind1--surely the world1 of all we have found in our wanderings1 which we should ourselves have chosen to be our home4 ,illustration3 ,,fig4 #gf4--;,,gassendi4 ,,nov4 #g1 #ahfg4 ,,vi4 ,,meteors4 ,what is truth8 ,what is fact1 and what is fancy1 even with regard to solid visible things that we may see and handle8 ,among the many superstitions of the early world and credulous fancies of the ,middle ,ages1 was the belief that great stones sometimes fell down out of heaven onto the earth4 ,pliny has a story of such a black stone1 big enough to load a chariot2 the ,mussulman still adores one at ,mecca2 and a medival emperor of ,germany had a sword which was said to have been forced from one of these bolts shot out of the blue4 ,but with the revival of learning1 people came to know better6 ,that stones should fall down from the sky was clearly1 they thought1 an absurdity2 indeed1 according to the learned opinion of that time1 one would hardly ask a better instance of the difference between the realities which science recognized and the absurdities which it condemned than the fancy that such a thing could be4 ,so at least the matter looked to the philosophers of the last century1 who treated it much as they might treat certain alleged mental phenomena1 for instance1 if they were alive to-day1 and at first refused to take any notice of these stories1 when from time to time they still came to hand4 ,when induced to give the matter consideration1 they observed that all the conditions for scientific observation were violated by these bodies1 since the wonder always happened at some far-off place or at some past time1 and 7suspicious circumstance67 the stones only fell in the presence of ignorant and unscientific witnesses1 and never when scientific men were at hand to examine the facts4 ,that there were many worthy1 if ignorant1 men who asserted that they had seen such stones fall1 seen them with their very eyes1 and held them in their own hands1 was accounted for by the general love of the marvellous and by the ignorance of the common mind1 unlearned in the conditions of scientific observation1 and unguided by the great principle of the uniformity of the ,laws of ,nature4 ,such a tone1 of course1 cannot be heard among us1 who never hastily pronounce anything a departure from the 8,laws of ,nature10 while uncertain that these can be separated from the laws of the fallible human mind1 in which alone ,nature is seen4 ,but in the last century philosophers had not yet become humble1 or scientific men diffident of the absoluteness of their own knowledge1 and so it seemed that no amount of evidence was enough to gain an impartial hearing in the face of the settled belief that the atmosphere extended only a few miles above the earth's surface1 and that the region beyond1 whence alone such things could come1 was an absolute void extending to the nearest planet4 ,illustration3 ,,fig4 #gg4--,,the ,,camp ,,at ,,mount ,,whitney4 7,,from 8,,professional ,,papers ,,of ,,the ,,signal ,,service10 ,,vol4 ,,xv47 ,it used to be supposed that we were absolutely isolated1 not only from the stars but from other planets1 by vast empty spaces extending from world to world1--regions altogether vacant except for some vagrant comet2 but of late years we are growing to have new ideas on this subject1 and not only to consider space as far from void or tenantless1 but to admit1 as a possibility at least1 that there is a sort of continuity between our very earth's surface1 the air above it1 and all which lies beyond the blue overarching dome of our own sky4 ,our knowledge of the physical nature of the universe without has chiefly come from what the spectroscope1 overleaping the space between us and the stars1 has taught us of them2 as a telegram might report to us the existence of a race across the ocean1 without telling anything of what lay between4 ,it would be a novel path to the stars1 and to the intermediate regions whence these once mythical stones are now actually believed to come1 if we could take the reader to them by a route which enabled us to note each step of a continuous journey from the earth's surface out into the unknown2 but if we undertake to start upon it1 he will understand that we must almost at the outset leave the ground of comparative certainty on which we have hitherto rested1 and need to speak of things on this road which are still but probabilities1 and even some which are little more than conjectures1 before we get to the region of comparative certainty again1--a region which1 strange to say1 exists far away from us1 while that of doubt lies close at hand1 for we may be said without exaggeration to know more about ,sirius than about the atmosphere a thousand miles above the earth's surface2 indeed1 it would be more just to say that we are sure not only of the existence but of the elements that compose a star1 though a million of times as far off as the sun1 while at the near point named we are not sure of so much as that the atmosphere exists at all4 ,to begin our outward journey in a literal sense1 we might rise from the earth's surface some miles in a balloon1 when we should find our progress stayed by the rarity of the air4 ,below us would be a gray cloud-ocean1 through which we could see here and there the green earth beneath1 while above us there would still be something in the apparently empty air1 for if the sun has just set it will still be light all round us4 ,something then1 in a cloudless sky1 still exists to reflect the rays towards us1 and this something is made up of separately invisible specks of dust and vapor1 but very largely of actual dust1 which probably forms the nucleus of each mist-particle4 ,that discrete matter of some kind exists here has long been recognized from the phenomena of twilight2 but it is1 ,i think1 only recently that we are coming to admit that a shell of actual solid particles in the form of dust probably encloses the whole globe1 up to far above the highest clouds4 ,in #ahha the writer had occasion to conduct a scientific expedition to the highest point in the territories of the ,united ,states1 on one of the summits of the ,sierra ,nevadas of ,southern ,california1 which rise even above the ,rocky ,mountains4 ,the illustration on page #agg represents the camp occupied by this party below the summit1 where the tents1 which look as if in the bottom of a valley1 are yet really above the highest zone of vegetation1 and at an altitude of nearly twelve thousand feet4 ,still above these rise the precipices of barren rock seen in the background1 their very bases far above the highest visible dust-clouds1 which overspread like a sea the deserts at the mountain's foot1--precipices which when scaled lift the observer into what is1 perhaps1 the clearest and purest air to be found in the world4 ,it will be seen from the mere looks of the landscape that we are far away here from ordinary sources of contamination in the atmosphere4 ,yet even above here on the highest peak1 where we felt as if standing on the roof of the continent and elevated into the great aerial currents of the globe1 the telescope showed particles of dust in the air1 which the geologists deemed to have probably formed part of the soil of ,china and to have been borne across the ,pacific1 but which also1 as we shall see later1 may owe something to the mysterious source of the phenomena already alluded to4 ,it is far from being indifferent to us that the dust is there2 for1 to mention nothing else1 without it1 it would be night till the sunrise1 and black night again as soon as the sun's edge disappeared below the horizon4 ,the morning and the evening twilight1 which in northern latitudes increase our average time of light by some hours1 and add very materially to the actual days of man's life1 are probably due almost wholly to particles scarcely visible in the microscope1 and to the presence of such atoms1 smaller than the very motes ordinarily seen in the sunbeam1 which1 as ,mr4 ,aitken has shown1 fill the air we breathe1--so minute and remote are the causes on which the habits of life depend4 ,before we can see that a part of this impalpable1 invisible dust is also perhaps a link between our world and other members of the solar system1 we must ask how it gets into the atmosphere4 ,is it blown up from the earth1 or does it fall down out of the miscalled 8void0 of space8 ,if we cast a handful of dust into the air1 it will not mount far above the hand unless we set the air in motion with it1 as in ascending smoke-currents2 and the greatest explosions we can artificially produce1 hurl their finer products but a few hundred feet at most from the soil4 ,utterly different are the forces of ,nature4 ,we have on page #ahc a reproduction from a photograph of an eruption of ,vesuvius1--a mere toy-volcano compared to ,etna or ,hecla4 ,but observe the smoke-cloud which rises high in the sunshine1 looking solid as the rounded snows of an ,alp1 while the cities and the sea below are in the shadow4 ,the smoke that mounts from the foreground1 where the burning lava-streams are pouring over the surface and firing the woods1 is of another kind from that rolling high above4 ,this comes from within the mountain1 and is composed of clouds of steam mingled with myriads of dust-particles from the comminuted products of the earth's interior2 and we can see ourselves that it is borne away on a level1 miles high in the upper air4 ,but what is this to the eruption of ,sumbawa or ,krakatao8 ,the latter occurred in #ahhc1 and it will be remembered that the air-wave started by the explosion was felt around the globe1 and that1 probably owing to the dust and water-vapor blown into the atmosphere1 the sunsets even in ,america became of that extraordinary crimson we all remember three years ago2 and coincidently1 that dim reddish halo made its appearance about the sun1 the world over1 which is hardly yet gone4#f ,very careful estimates of the amount of ashes ejected have been made2 and though most of the heavier particles are known to have fallen into the sea within a few miles1 a certain portion--the lightest--was probably carried by the explosion far above the lower strata of the atmosphere1 to descend so slowly that some of it may still be there4 ,of this lighter class the most careful estimates must be vague2 but according to the report of the official investigation by the ,dutch ,government1 that which remained floating is something enormous4 ,an idea of its amount may be gained by supposing these impalpable and invisible particles to condense again from the upper sky1 and to pour down on the highest edifice in the world1 the ,washington ,monument4 ,if the dust were allowed to spread out on all sides1 till the pyramidal slope was so flat as to be permanent1 the capstone of the monument would not only be buried before the supply was exhausted1 but buried as far below the surface as that pinnacle is now above it4 #f ,in ,january1 #ahhg4 ,of the explosive suddenness with which the mass was hurled1 we can judge something 7comparing small things with great7 by the explosion of dynamite4 ,it happened once that the writer was standing by a car in which some railway porters were lifting boxes4 ,at that moment came an almost indescribable sound1 for it was literally stunning1 though close and sharp as the crack of a whip in one's hand1 and yet louder than the nearest thunder-clap4 ,the men leaped from the car1 thinking that one of the boxes had exploded between them2 but the boxes were intact1 and we saw what seemed a pillar of dust rising above the roof of the station1 hundreds of yards away4 ,when we hurried through the building1 we found nothing on the other side but a bare plain1 extending over a mile1 and beyond this the actual scene of the explosion that had seemed to be at our feet4 ,there had been there1 a few minutes before1 extensive buildings and shops belonging to the railroad1 and sidings on which cars were standing1 two of which1 loaded with dynamite1 had exploded4 ,illustration3 ,,fig4 #gh4--,,vesuvius ,,during ,,an ,,eruption4 ,where they had been was a crater-like depression in the earth1 some rods in diameter2 the nearest buildings1 great solid structures of brick and stone1 had vanished1 and the more distant wooden ones and the remoter lines of freight-cars on the side-tracks presented a curious sight1 for they were not shattered so much as bent and leaning every way1 as though they had been built of pasteboard1 like card-houses1 and had half yielded to some gigantic puff of breath4 ,all that the explosion had shot skyward had settled to earth or blown away before we got in sight of the scene1 which was just as quiet as it had been a minute before4 ,it was like one of the changes of a dream4 ,now1 it is of some concern to us to know that the earth holds within itself similar forces1 on an incomparably greater scale4 ,for instance1 the explosion which occurred at ,krakatao1 at five minutes past ten1 on the #bgth of ,august1 #ahhc1 according to official evidence1 was heard at a distance of eighteen hundred miles1 and the puff of its air-wave injured dwellings two hundred miles distant1 and1 we repeat1 carried into the highest regions of the atmosphere and around the world matter which it is at least possible still affects the aspect of the sun to-day from ,new ,york or ,chicago4 ,do not the great flames which we have seen shot out from the sun at the rate of hundreds of miles a second1 the immense and sudden perturbations in the atmosphere of ,jupiter1 and the scarred surface of the moon1 seem to be evidences of analogous phenomena1 common to the whole solar system1 not wholly unconnected with those of earthquakes1 and which we can still study in the active volcanoes of the earth8 ,if the explosion of gunpowder can hurl a cannon-shot three or four miles into the air1 how far might the explosion of ,krakatao cast its fragments8 ,at first we might think there must be some proportionality between the volume of the explosion and the distance1 but this is not necessarily so4 ,apart from the resistance of the air1 it is a question of the velocity with which the thing is shot upward1 rather than the size of the gun1 or the size of the thing itself1 and with a sufficient velocity the projectile would never fall back again4 8,what goes up must come down10 is1 like most popular maxims1 true only within the limits of ordinary experience2 and even were there nothing else in the universe to attract it1 and though the earth's attraction extend to infinity1 so that the body would never escape from it1 it is yet quite certain that it would1 with a certain initial velocity 7very moderate in comparison with that of the planet itself71 go up and never come back2 while under other and possible conditions it might voyage out into space on a comet-like orbit1 and be brought back to the earth1 perhaps in after ages1 when the original explosion had passed out of memory or tradition4 ,but because all this is possible1 it does not follow that it is necessarily true2 and if the reader ask why he should then be invited to consider such suppositions at all1 we repeat that in our journey outward1 before we come to the stars1 of which we know something1 we pass through a region of which we know almost nothing2 and this region1 which is peopled by the subjects of conjecture1 is the scene1 if not the source1 of the marvel of the falling stones1 concerning which the last century was so incredulous1 but for which we can1 aided by what has just been said1 now see at least a possible cause1 and to which we now return4 ,stories of falling stones1 then1 kept arising from time to time during the last century as they had always done1 and philosophers kept on disbelieving them as they had always done1 till an event occurred which suddenly changed scientific opinion to compulsory belief4 ,on the #bfth of ,april1 #ahjc1 there fell1 not in some far-off part of the world1 but in ,france1 not one alone1 but many thousand stones1 over an area of some miles1 accompanied with noises like the discharge of artillery4 ,a committee of scientific men visited the spot on the part of the ,french ,institute1 and brought back not only the testimony of scores of witnesses or auditors1 but the stones themselves4 ,soon after stones fell in ,connecticut1 and here and elsewhere1 as soon as men were prepared to believe1 they found evidence multiplied2 and such falls1 it is now admitted1 though rare in any single district1 are of what may be called frequent occurrence as regards the world at large1--for1 taking land and sea together1 the annual stone-falls are probably to be counted by hundreds4 ,it was early noticed that these stones consisted either of a peculiar alloy of iron1 or of minerals of volcanic origin1 or both2 and the first hypothesis was that they had just been shot out from terrestrial volcanoes4 ,as they were however found1 as in the case of the ,connecticut meteorite1 thousands of miles from any active volcanoes1 and were seen to fall1 not vertically down1 but as if shot horizontally overhead1 this view was abandoned4 ,next the idea was suggested that they were coming from volcanoes in the moon2 and though this had little to recommend it1 it was adopted in default of a better1 and entertained down to a comparatively very recent period4 ,these stones are now collected in museums1 where any one may see them1 and are to be had of the dealers in such articles by any who wish to buy them4 ,they are coming to have such a considerable money value that1 in one case at least1 a lawsuit has been instituted for their possession between the finder1 who had picked the stones up on ground leased to him1 and claimed them under the tenant's right to wild game1 and his landlord1 who thought they were his as part of the real estate4 ,leaving the decision of this novel law-point to the lawyers1 let us notice some facts now well established4 ,the fall is usually preceded by a thundering sound1 sometimes followed or accompanied by a peculiar noise described as like that of a flock of ducks rising from the water4 ,the principal sound is often1 however1 far louder than any thunder1 and sometimes of stunning violence4 ,at night this is accompanied by a blaze of lightning-like suddenness and whiteness1 and the stones commonly do not fall vertically1 but as if shot from a cannon at long range4 ,they are usually burning hot1 but in at least one authenticated instance one was so intensely cold that it could not be handled4 ,they are of all sizes1 from tons to ounces1 comparatively few1 however1 exceeding a hundred-weight1 and they are oftenest of a rounded form1 or looking like pieces of what was originally round1 and usually wholly or partly covered with a glaze formed of the fused substance itself4 ,if we slowly heat a lump of loaf sugar all through1 it will form a pasty mass1 while we may also hold it without inconvenience in our fingers to the gas-flame a few seconds1 when it will be melted only on the side next the sudden heat1 and rounded by the melting4 ,the sharp contrast of the melted and the rough side is something like that of the meteorites2 and just as the sugar does not burn the hand1 though close to where it is brought suddenly to a melting heat1 a mass of ironstone may be suddenly heated on the surface1 while it remains cold on the inside4 ,but1 however it got there1 the stone undoubtedly comes from the intensely cold spaces above the upper air2 and what is the source of such a heat that it is melted in the cold air1 and in a few seconds8 ,illustration3 ,,fig4 #gi4--,,meteors ,,observed ,,nov4 #ac ,,and #ad1 #ahfh1 ,,between ,,midnight ,,and ,,five ,o',,clock1 ,a4 ,m4 ,everybody has noticed that if we move a fan gently1 the air parts before it with little effort1 while1 when we try to fan violently1 the same air is felt to react2 yet if we go on to say that if the motion is still more violent the atmosphere will resist like a solid1 against which the fan1 if made of iron1 would break in pieces1 this may seem to some an unexpected property of the 8nimble0 air through which we move daily4 ,yet this is the case2 and if the motion is only so quick that the air cannot get out of the way1 a body hurled against it will rise in temperature like a shot striking an armor-plate4 ,it is all a question of speed1 and that of the meteorite is known to be immense4 ,one has been seen to fly over this country from the ,mississippi to the ,atlantic in an inappreciably short time1 probably in less than two minutes2 and though at a presumable height of over fifty miles1 the velocity with which it shot by gave every one the impression that it went just above his head1 and some witnesses of the unexpected apparition looked the next day to see if it had struck their chimneys4 ,the heat developed by arrested motion in the case of a mass of iron moving twenty miles a second can be calculated1 and is found to be much more than enough1 not only to melt it1 but to turn it into vapor2 though what probably does happen is1 according to ,professor ,newton1 that the melted surface-portions are wiped away by the pressure of the air and volatilized to form the luminous train1 the interior remaining cold1 until the difference of temperature causes a fracture1 when the stone breaks and pieces fall1--some of them at red-hot heat1 some of them possibly at the temperature of outer space1 or far below that of freezing mercury4 ,where do these stones come from8 ,what made them8 ,the answer is not yet complete2 but if a part of the riddle is already yielding to patience1 it is worthy of note1 as an instance of the connection of the sciences1 that the first help to the solution of this astronomical enigma came from the chemists and the geologists4 ,the earliest step in the study1 which has now been going on for many years1 was to analyze the meteorite1 and the first result was that it contained no elements not found on this planet4 ,the next was that1 though none of these elements were unknown1 they were not combined as we see them in the minerals we dig from the earth4 ,next it was found that the combinations1 if unfamiliar at the earth's surface and nowhere reproduced exactly1 were at least very like such as existed down beneath it1 in lower strata1 as far as we can judge by specimens of the earth's interior cast up from volcanoes4 ,later1 a resemblance was recognized in the elements of the meteorites to those found by the spectroscope in shooting stars1 though the spectroscopic observation of the latter is too difficult to have even yet proceeded very far4 ,and now1 within the last few years1 we seem to be coming near to a surprising solution4 ,it has now been shown that meteoric stones sometimes contain pieces of essentially different rocks fused together1 and pieces of detritus1--the wearing down of older rocks4 ,thus1 as we know that sandstone is made of compacted sand1 and sand itself was in some still earlier time part of rocks worn down by friction1--when it is shown1 as it has been by ,m4 ,meunier1 that a sandstone penetrated by metallic threads 7like some of our terrestrial formations7 has come to us in a meteorite1 the conclusion that these stones may be part of some old world is one that1 however startling1 we cannot refuse at least to consider4 ,according to this view1 there may have been a considerable planet near the earth1 which1 having reached the last stage of planetary existence shown in the case of our present moon1 went one step further1--went1 that is1 out of existence altogether1 by literal breaking up and final disappearance4 ,we have seen the actual moon scarred and torn in every direction1 and are asked to admit the possibility that a continuance of the process on a similar body has broken it up into the fragments that come to us4 ,we do not say that this is the case1 but that 7as regards the origin of some of the meteorites at least7 we cannot at present disprove it4 ,we may1 at any rate1 present to the novelist seeking a new motif that of a meteorite bringing to us the story of a lost race1 in some fragment of art or architecture of its lost world6 ,we are not driven to this world-shattering hypothesis by the absence of others1 for we may admit these to be fragments of a larger body without necessarily concluding that it was a world like ours1 or1 even if it were1 that the world which sent them to us is destroyed4 ,in view of what we have been learning of the tremendous explosive forces we see in action on the sun and probably on other planets1 and even in terrestrial volcanoes to-day1 it is certainly conceivable that some of these stones may have been ejected by some such process from any sun1 or star1 or world we see4 ,the reader is already prepared for the suggestion that part of them may be the product of terrestrial volcanoes in early epochs1 when our planet was yet glowing sunlike with its proper heat1 and the forces of ,nature were more active2 and that these errant children of mother earth's youth1 after circulating in lengthened orbits1 are coming back to her in her age4 ,do not let us1 however1 forget that these are mostly speculations only1 and perhaps the part of wisdom is not to speculate at all till we learn more facts2 but are not the facts themselves as extraordinary as any invention of fancy8 ,although it is true that the existence of the connection between shooting stars and meteorites lacks some links in the chain of proof1 we may very safely consider them together2 and if we wish to know what the ,new ,astronomy has done for us in this field1 we should take up some treatise on astronomy of the last century4 ,we turn in one to the subject of falling stars1 and find that 8this species of ,star is only a light ,exhalation1 almost wholly sulphurous1 which is inflamed in the free ,air much after the same manner as ,thunder in a ,cloud by the blowing of the ,winds40 ,that the present opinion is different1 we shall shortly notice4 ,all of us have seen shooting stars1 and they are indeed something probably as old as this world1 and have left their record in mythology as well as in history4 ,according to ,moslem tradition1 the evil genii are accustomed to fly at night up to the confines of heaven in order to overhear the conversation of the angels1 and the shooting stars are the fiery arrows hurled by the latter at their lurking foes1 with so good an aim that we are told that for every falling star we may be sure that there is one spirit of evil the less in the world4 ,the scientific view of them1 however1 if not so consolatory1 is perhaps more instructive1 and we shall here give most attention to the latter4 ,to begin with1 there have been observed in history certain times when shooting stars were unusually numerous4 ,the night when ,king ,ibrahim ,ben ,ahmed died1 in ,october1 #ijb1 was noted by the ,arabians as remarkable in this way2 and it has frequently been observed since1 that1 though we can always see some of these meteors nightly1 there are at intervals very special displays of them4 ,the most notable modern one was on ,nov4 #ac1 #ahcc1 and this was visible over much of the ,north ,american continent1 forming a spectacle of terrifying grandeur4 ,an eyewitness in ,south ,carolina wrote3-- 8,i was suddenly awakened by the most distressing cries that ever fell on my ears4 ,shrieks of horror and cries for mercy ,i could hear from most of the negroes of the three plantations1 amounting in all to about six hundred or eight hundred4 ,while earnestly listening for the cause ,i heard a faint voice near the door1 calling my name4 ,i arose1 and1 taking my sword1 stood at the door4 ,at this moment ,i heard the same voice still beseeching me to rise1 and saying1 #8,o my ,god1 the world is on fire6' ,i then opened the door1 and it is difficult to say which excited me the most--the awfulness of the scene1 or the distressed cries of the negroes4 ,upwards of one hundred lay prostrate on the ground1--some speechless and some with the bitterest cries1 but with their hands raised1 imploring ,god to save the world and them4 #8,the scene was truly awful2 for never did rain fall much thicker than the meteors fell toward the earth2 east1 west1 north1 and south1 it was the same40 ,the illustration on page #ahi does not exaggerate the number of the fiery flashes at such a time1 though the zigzag course which is observed in some is hardly so common as it here appears4 ,when it was noted that the same date1 ,november #acth1 had been distinguished by star-showers in #ahca and #ahcb1 and that the great shower observed by ,humboldt in #agii was on this day1 the phenomenon was traced back and found to present itself about every thirty-three years1 the tendency being to a little delay on each return2 so that ,professor ,newton and others have found it possible with this clew to discover in early ,arabic and other medival chronicles1 and in later writers1 descriptions which1 fitted together1 make a tolerably continuous record of this thirty-three-year shower1 beginning with that of ,king ,ibrahim already alluded to4 ,the shower appeared again in ,november1 #ahfg and #ahfh1 with less display1 but with sufficient brilliance to make the writer well remember the watch through the night1 and the count of the flying stars1 his most lively recollection being of their occasional colors1 which in exceptional cases ranged from full crimson to a vivid green4 ,the count on this night was very great1 but the number which enter the earth's atmosphere even ordinarily is most surprising2 for1 though any single observer may note only a few in his own horizon1 yet1 taking the world over1 at least ten millions appear every night1 and on these special occasions very many more4 ,this ,november shower comes always from a particular quarter of the sky1 that occupied by the constellation ,leo1 but there are others1 such as that of ,august #ajth 7which is annual71 in which the 8stars0 seem to be shot at us from the constellation ,perseus2 and each of the numerous groups of star-showers is now known by the name of the constellation whence it seems to come1 so that we have ,perseids on ,august #ajth1 ,geminids on ,december #abth1 ,lyrids1 ,april #bjth1 and so on4 ,the great ,november shower1 which is coming once more in this century1 and which every reader may hope to see toward #ahii1 is of particular interest to us as the first whose movements were subjected to analysis2 for it has been shown by the labors of ,professor ,newton1 of ,yale1 and ,adams1 of ,cambridge1 that these shooting stars are bodies moving around the sun in an orbit which is completed in about thirty-three years4 ,it is quite certain1 too1 that they are not exhalations from the earth's atmosphere1 but little solids1 invisible till they shine out by the light produced by their own fusion4 ,each1 then1 moves on its own track1 but the general direction of all the tracks concurs2 and though some of them may conceivably be solidified gases1 we should think of them not as gaseous in form1 but as solid shot1 of the average size of something like a cherry1 or perhaps even of a cherry-stone1 yet each an independent planetoid1 flying with a hundred times the speed of a rifle-bullet on its separate way as far out as the orbit of ,uranus2 coming back three times in a century to about the earth's distance from the sun1 and repeating this march forever1 unless it happen to strike the atmosphere of the earth itself1 when there comes a sudden flash of fire from the contact1 and the distinct existence of the little body1 which may have lasted for hundreds of thousands of years1 is ended in a second4 ,if the reader will admit so rough a simile1 we may compare such a flight of these bodies to a thin swarm of swift-flying birds--thin1 but yet immensely long1 so as to be1 in spite of the rapid motion1 several years in passing a given point1 and whose line of flight is cut across by us on the #acth of ,november1 when the earth passes through it4 ,we are only there on that day1 and can only see it then2 but the swarm is years in all getting by1 and so we may pass into successive portions of it on the anniversary of the same day for years to come4 ,the stars appear to shoot from ,leo1 only because that constellation is in the line of their flight when we look up to it1 just as an interminable train of parallel flying birds would appear to come from some definite point on the horizon4 ,we can often see the flashes of meteors at over a hundred miles1 and though at times they may seem to come thick as ,hakes of falling snow1 it is probable1 according to ,professor ,newton1 that even in a 8shower0 each tiny planetoid is more than ten miles from its nearest neighbor1 while on the average it is reckoned that we may consider that each little body1 though possibly no larger than a pea1 is over two hundred miles from its neighbor1 or that to each such grain there is nearly ten million cubic miles of void space4 ,their velocity as compounded with that of the earth is enormous1 sometimes forty to fifty miles per second 7according to a recent but unproved theory of ,mr4 ,denning1 it would be much greater71 and it is this enormous rate of progress that affords the semblance of an abundant fall of rain1 notwithstanding the distance at which one drop follows another4 ,it is only from their light that we are able to form a rough estimate of their average size1 which is1 as we have seen1 extremely small2 but1 from their great number1 the total weight they add to the earth daily may possibly be a hundred tons1 probably not very much more4 ,as they are as a rule entirely dissipated in the upper air1 often at a height of from fifty to seventy miles1 it follows that many tons of the finest pulverized and gaseous matter are shot into the earth's atmosphere every twenty-four hours from outer space1 so that here is an independent and constant supply of dust1 which we may expect to find coming down from far above the highest clouds4 ,now1 when the reader sees the flash of a shooting star1 he may1 if he please1 think of the way the imagination of the ,east accounts for it1 or he may look at what science has given him instead4 ,in the latter case he will know that a light which flashed and faded almost together came from some strange little entity which had been traversing cold and vacant space for untold years1 to perish in a moment of more than fiery heat2 an enigma whose whole secret is unknown1 but of which1 during that instant flash1 the spectroscope caught a part1 and found evidence of the identity of some of its constituents with those of the observer's own body4 ,,vii4 ,,comets4 ,of comets1 the ,old ,astronomy knew that they came to the sun from great distances in all directions1 and in calculable orbits2 but as to what they were1 this1 even in the childhood of those of us who are middle-aged1 was as little known as to the centuries during which they still from their horrid heads shook pestilence and war4 ,we do not know even now by any means exactly what they are1 for enough yet remains to be learned about them still to give their whole study the attraction which belongs to the unknown2 and yet we learn so much1 and in a way which to our grandfathers would have been so unexpected1 connecting together the comet1 the shooting star1 and the meteorite1 that the astronomer who perhaps speaks with most authority about these to-day was able1 not long ago1 in beginning a lecture1 to state that he held in his hand what had been a part of a comet2 and what he held was1 not something half vaporous or gaseous1 as we might suppose from our old associations1 but a curious stone like this on page #bjc1 which1 with others1 had fallen from the sky in ,iowa1 a flashing prodigy1 to the terror of barking dogs1 shying horses1 and fearful men1 followed by clouds of smoke and vapor1 and explosions that shook the houses like an earthquake1 and 8hollow bellowings and rattling sounds mingled with clang and clash and roar10 as an auditor described it4 ,it is only a fragment of a larger stone which may have weighed tons4 ,it looks inoffensive enough now1 and its appearance affords no hint of the commotion it caused in a peaceable neighborhood only ten years ago4 ,but what1 it may be asked1 is the connection between such things and comets8 ,to answer this1 let us recall the statement that the orbit of the ,november meteor swarm has been computed2 which means that those flying bodies have been found to come only from one particular quarter out of all possible quarters1 at one particular angle out of all possible angles1 at one particular velocity out of all possible velocities1 and so on2 so that the chances are endless against mere accident producing another body which agreed in all these particulars1 and others besides4 ,now1 in #ahfg the remarkable fact was established that a comet seen in the previous year 7,comet #a1 #ahff7 had the same orbit as the meteoroids1 which implies1 as we have just seen1 that the comet and the meteors were in some way closely related4 ,the paths of the ,august meteors and of the ,lyrids also have both been found to agree closely with those of known comets1 and there is other evidence which not only connects the comets and the shooting stars1 and makes it probable that the latter are due to some disintegration of the former1 but even looks as though the process were still going on4 ,and now with this in mind we may1 perhaps1 look at these drawings with more interest4 ,illustration3 ,,fig4 #hj4--;,,comet ,,of ,,donati1 ,,sept4 #af1 #aheh4g #g ,the five engravings of the ,comet of ,donati are from 8,annals of the ,astronomical ,observatory of ,harvard ,college40 ,we have all seen a comet1 and we have all felt1 perhaps1 something of the awe which is called up by the thought of its immensity and its rush through space like a runaway star4 ,its head is commonly like a small luminous point1 from which usually grows as it approaches the sun a relatively enormous brush or tail of pale light1 which has sometimes been seen to stretch across the whole sky from zenith to horizon4 ,it is useless to look only along the ecliptic road for a comet's coming2 rather may we expect to see it rushing down from above1 or up from below1 sometimes with a speed which is possibly greater than it could get from any fall--not so much1 that is1 the speed of a body merely dropping toward the sun by its weight1 as that of a missile hurled into the orderly solar system from some unknown source without1 and also associated with some unknown power2 for while it is doubtful whether gravity is sufficient to account for the velocity of all comets1 it seems certain that gravity can in no way explain some of the phenomena of their tails4 ,illustration3 ,,fig4 #ha4--8;,a ,,part ,,of ,a ,,comet40 ,thousands of comets have been seen since the ,christian era1 and the orbits of hundreds have been calculated since the time of ,newton4 ,though they may describe any conic section1 and though most orbits are spoken of as parabolas1 this is rather a device for the analyst's convenience than the exact representation of fact4 ,without introducing more technical language1 it will be enough to say here that we learn in other cases from the form of the orbit whether the body is drawn essentially by the sun's gravity1 or whether it has been thrown into the system by some power beyond the sun's control1 to pass away again1 out of that control1 never to return4 ,it must be admitted1 however1 that though several orbits are so classed1 there is not any one known to be beyond doubt of this latter kind1 while we are certain that many comets1 if not all1 are erratic members of the solar family1 coming back again after their excursions1 at regular1 though perhaps enormous1 intervals4 ,but what we have just been saying belongs rather to the province of the ,old ,astronomy than the ,new1 which concerns itself more with the nature and appearance of the heavenly bodies than the paths they travel on4 ,perhaps the best way for us to look at comets will be to confine our attention at first to some single one1 and to follow it from its earliest appearance to its last1 by the aid of pictures1 and thus to study1 as it were1 the species in the individual4 ,the difficulty will be one which arises from the exquisitely faint and diaphanous appearance of the original1 which no ordinary care can possibly render1 though here the reader has had done for him all that the wood-engraver can do4 ,we will take as the subject of our illustration the beautiful comet which those of us who are middle-aged can remember seeing in #aheh1 and which is called ,donati's from the name of its discoverer4 ,we choose this one because it is the subject of an admirable monograph by ,professor ,bond of the ,harvard ,college ,observatory1 from which our engravings have1 by permission1 been made4 ,let us take the history of this comet1 then1 as a general type of others2 and to begin at the beginning1 we must make the very essential admission that the origin of the comet's life is unknown to us4 ,where it was born1 or how it was launched on its eccentric path1 we can only guess1 but do not know2 and how long it has been traversing it we can only tell later4 ,on the #b;d of ,june1 #aheh1 this one was discovered in the way most comets are found1 that is1 by a comet-hunter1 who detected it as a telescopic speck long before it became visible to the naked eye1 or put forth the tail which was destined to grow into the beautiful object many of us can remember seeing4 ,for over a century now there has been probably no year in which the heavens have not been thus searched by a class of observers who make comet-hunting a specialty4 ,illustration3 ,,fig4 #hb4--;,,comet ,,of ,,donati1 ,,sept4 #bd1 #aheh4 7,,telescopic ,,view ,,of ,,head47 ,the father of this very valuable class of observers appears to have been ,messier1 a ,frenchman of the last century and of the purest type of the comet-hunters1 endowed by ,nature with the instinct for their search that a terrier has for rats4 ,in that grave book1 ,delambre's 8,history of ,astronomy10 as we plod along its dry statements and through its long equations1 we find1 unexpected as a joke in a table of logarithms1 the following piece of human nature 7quoted from ,messier's contemporary1 ,la ,harpe73-- 8,he ,messier has passed his life in nosing out the tracks of comets4 ,he is a very worthy man1 with the simplicity of a baby4 ,some years ago he lost his wife1 and his attention to her prevented him from discovering a comet he was on the search for1 and which ,montaigne of ,limoges got away from him4 ,he was in despair4 ,when he was condoled with on the loss he had met1 he replied1 with his head full of the comet1 #8,oh1 dear6 to think that when ,i had discovered twelve1 this ,montaigne should have got my thirteenth4' ,and his eyes filled with tears1 till1 remembering what it was he ought to be weeping for1 he moaned1 #8,oh1 my poor wife6' but went on crying for his comet40 ,messier's scientific posterity has greatly multiplied1 and it is rare now for a comet to be seen by the naked eye before it has been caught by the telescope of one of these assiduous searchers4 ,donati had1 as we see1 observed his some months before it became generally visible1 and accordingly the engraving on page #bja shows it as it appeared on the evening of ,september #af1 #aheh1 when the tail was already formed1 and1 though small1 was distinct to the naked eye1 near the stars of the ,great ,bear4 ,the reader will easily recognize in the plate the familiar 8dipper10 as the ,american child calls it1 where the leading stars are put down with care1 so that he may1 if he please1 identify them by comparison with the originals in the sky1 even to the little companion to ,mizar 7the second in the handle of the 8dipper10 and which the ,arabs say is the lost ,pleiad74 ,we would suggest that he should note both the length of the tail on this evening as compared with the space between any two stars of the 8dipper0 7for instance1 the two right-hand ones1 called the 8pointers07 and its distance from them1 and then turn to page #bji1 where we have the same comet as seen a little over a fortnight later1 on ,october #c;d4 ,look first at its new place among the stars4 ,the 8dipper0 is still in view1 but the comet has drifted away from it toward the left and into other constellations4 ,the large star close to the left margin of the plate1 with three little stars below and to the right1 is ,arcturus2 and the western stars of the ,northern ,crown are just seen higher up4 ,fortunately the 8pointers10 with which we compared the comet on ,september #afth1 are still here1 and we can see for ourselves how it has not only shifted but grown4 ,the tail is three times as long as before4 ,it is rimmed with light on its upper edge1 and fades away so gradually below that one can hardly say where it ends4 ,but1--wonderful and incomprehensible feature6--shot out from the head1 almost as straight as a ray of light itself1 but fainter than the moonbeam1 now appears an extraordinary addition1 a sort of spur1 which we can hardly call a new tail1 it is so unlike the old one1 but which appears to have been darted out into space as if by some mysterious force acting through the head itself4 ,what the spur is1 what the tail is1 even what the nucleus is1 we cannot be said really to know even to-day2 but of the tail and of the nucleus or speck in the very head of the comet 7too small to be visible in the engraving71 we may say that the hairy tail 7comes7 gives the comet its name1 and is the comet to popular apprehension1 but that it is probably the smallest part of the whole mass1 while the little shining head1 which to the telescope presents a still smaller speck called the nucleus1 contains1 it now seems probable1 the only element of possible danger to the earth4 ,while admitting our lack of absolute knowledge1 we may1 if we agree that meteorites were once part of a comet1 say that it now seems probable that the nucleus is a hard1 stone-like mass1 or collection of such masses1 which comes from 8space0 7that is1 from we don't know how far7 to the vicinity of the sun1 and there is broken by the heat as a stone in a hot fire4 7,sir ,isaac ,newton calculates1 in an often quoted passage of the ,principia1 that the heat which the comet of #afhj was subjected to in its passage by the sun was two thousand times that of red-hot iron47 ,we have seen the way in which meteoric stones actually do crack in pieces with heat in our own atmosphere1 partly1 perhaps1 from the expansion of the gases the stone contains1 and it seems entirely reasonable to suppose that they may do so from the heat of the sun1 and that the escaped gases may contribute something toward the formation of the tail1 which is always turned away from the sun1 and which always grows larger as that is approached1 and smaller as it is receded from4 ,however this may be1 there is no doubt that the original solid which we here suppose may form the nucleus is capable of mischief1 for it is asserted that it often passes the earth's orbit with a velocity of as much as one hundred times that of a cannon-ball2 that is1 with ten thousand times the destructive capacity of a ball of the same weight shot from a cannon4 ,illustration3 ,,fig4 #hc4--;,,comet ,,of ,,donati1 ,,oct4 #c1 #aheh4 ,one week later1 ,october #ith1 the comet had passed over ,arcturus with a motion toward our left into a new region of the sky1 leaving ,arcturus1 which we can recognize with the upper one of its three little companions1 on the right4 ,above it is the whole sickle of the ,northern ,crown1 and over these stars the extremity of the now lengthened tail was seen to spread1 but with so thin a veil that no art of the engraver can here adequately represent its faintness4 ,the tail then1 as seen in the sky1 was now nearly twice its former size1 though for the reason mentioned it may not appear so in our picture4 ,it should be understood1 too1 that even the brightest parts of the original were far fainter than they seem here in comparison with the stars1 which in the sky are brilliant points of light1 which the engraver can only represent by dots of the whiteness of the paper4 ,this being observed1 it will be better understood that in the sky itself the faintest stars were viewed apparently undimmed through the brighter parts of the comet1 while we can but faintly trace here another most faint but curious feature1 a division of the tail into faint cross-bands like auroral streamers1 giving a look as if it were yielding to a wind1 which folded it into faint ridges like those which may be seen in the smoke of a steamer as it lags far behind the vessel4 ,in fact1 when we speak of 8the0 tail1 it must be understood1 as ,m4 ,faye reminds us1 to be in the same sense that we speak of the plume of smoke that accompanies an ocean steamer1 without meaning that it is the same thing which we are watching from night to night1 more than we do that the same smoke-particles accompany the steamer as it moves across the ,atlantic4 ,in both cases the form alone probably remains2 the thing itself is being incessantly dissipated and renewed4 ,there is no air here1 and yet some of these appearances in the original almost suggest the idea of medium inappreciably thin as compared with the head of the comet1 but whose resistance is seen in the more unsubstantial tail1 as that is drawn through it and bent backward1 as if by a wind blowing toward the celestial pole4 ,the most notable feature1 however1 is the development of a second ray or spur1 which has been apparently darted through millions of miles in the interval since we looked at it1 and an almost imperceptible bending backward in both1 as if they too felt the resistance of something in what we are accustomed to think of as an absolute and perfect void4 ,these tails are a peculiarly mysterious feature4 ,they are apparently shot out in a direction opposite to the sun 7and consequently opposed to the direction of gravity7 at the rate of millions of miles a day4 ,illustration3 ,,fig4 #hd4--;,,comet ,,of ,,donati1 ,,oct4 #i1 #aheh4 ,beyond the fact that the existence of some repulsive force in the sun1 a 8negative gravity0 actually existent1 not in fancy1 but in fact1 seems pointed at1 astronomers can offer little but conjecture here2 and while some conceive this force as of an electrical nature1 others strenuously deny it4 ,we ought to admit that up to the present time we really know nothing about it1 except that it exists4 ,at this date 7,october #ith7 the comet had made nearly its closest approach to the earth1 and the general outline has been compared to that of the wing of some bird1 while the actual size was so vast that even at the distance from which it was seen it filled an angle more than half of that from the zenith to the horizon4 ,all the preceding drawings have been from naked-eye views2 but if the reader would like to look more closely1 he can see on page #bag one taken on the night of ,october #eth through the great telescope at ,cambridge1 ,mass4 ,we will leave this to tell its own story1 only remarking that it is not possible to reproduce the phantom-like faintness of the original spur1 here also distinctly seen1 or indeed to indicate fairly the infinite tenuity of the tail itself4 ,though millions of miles thick1 the faintest star is yet perceptibly undimmed by it1 and in estimating the character and quantity of matter it contains1 after noting that it is not self-luminous1 but shines only like the moon by reflected sunlight1 we may recall the acute observation of ,sir ,isaac ,newton where he compares the brightness of a comet's tail with that of the light reflected from the particles in a sunbeam an inch or two thick1 in a darkened room1 and1 after observing that if a little sphere of common air one inch in diameter were rarified to the degree which must obtain at only four thousand miles from the earth's surface it would fill all the regions of the planets to far beyond the orbit of ,saturn1 suggests the excessively small quantity of vapor that is really requisite to create this prodigious phantom4 ,the writer has had occasion for many years to make a special study of the reflection of light from the sky2 and if such studies may authorize him to express any opinion of his own1 he would give his adhesion to the remark of ,sir ,john ,herschel1 that the actual weight of matter in such a cometary tail may be conceivably only an affair of pounds or even ounces4 ,but if this is true of the tail1 it does not follow of the nucleus1 just seen in this picture1 but of which the engraving on page #bje gives a much more magnified view4 ,it is a sketch of the head alone1 taken from a telescopic view on the #bdth of ,september4 ,here the direction of the comet is still toward the sun 7which must be supposed to be some indefinite distance beyond the upper part of the drawing71 and we see that the lucid matter appears to be first jetted up1 and then forced backward on either side1 as if by a wind from the sun1 to form the tail1 presenting successive crescent-shaped envelopes of decreasing brightness1 which are not symmetrical1 but one-sided1 while sometimes the appearance is that of spurts of luminous smoke1 wavering as if thrown out of particular parts of the internal nucleus 8like a squib not held fast40 ,down the centre of the tail runs a wonderfully straight black line1 like a shadow cast from the nucleus4 ,only the nucleus itself still evades us1 and even in this1 the most magnified view which the most powerful telescope till lately in existence could give1 remains a point4 ,considering the distance of the comet and the other optical conditions1 this is still perfectly consistent with the possibility that it may have an actual diameter of a hundred miles or more4 ,it 8may0 have1 observe1 not it 8has10 for in fact we know nothing about it2 but that it is at any rate less than some few hundred miles in diameter1 and it may1 for anything we can positively say1 not be more than a very large stone1 in which case our atmosphere would probably act as an efficient buffer if it struck us2 or it may have a mass which1 coupled with its terrible speed1 would cause the shock of its contact not so much to pulverize the region it struck1 as dissipate it and everything on it instantly into vapor4 ,illustration3 ,,fig4 #he4--;,,comet ,,of ,,donati1 ,,oct4 #e1 #aheh4 7,,telescopic ,,view47 ,of the remarkable investigations of the spectroscope on comets1 we have only room left to say that they inform us that the most prominent cometary element seems to be carbon1--carbon1 which ,newton two hundred years before the spectroscope1 and before the term 8carbonic-acid gas0 was coined1 by some guess or divination had described in other words as possibly brought to us by comets to keep up the carbonic-acid-gas supply in our air1--carbon1 which we find in our own bodies1 and of which1 according to this view1 the comets are original sources4 ,that we may be partly made of old and used-up comets1--surely it might seem that a madder fancy never came from the brain of a lunatic at the full of the moon6 ,science may easily be pardoned for not giving instant reception to such an idea1 but let us also remember1 first1 that it is a consequence of that of ,sir ,isaac ,newton1 and that in the case of such a man as he we should not be hasty to think we understand his ignorance1 when we may be 8ignorant of his understanding20 and1 second1 that it has been rendered at least debatable by ,dr4 ,hunt's recent researches whether it is possible to account for the perennial supply of carbon from the earth's atmosphere1 without looking to some means of renewal external to the planet4 ,the old dread of comets is passing away1 and all that science has to tell us of them indicates that1 though still fruitful sources of curiosity and indeed of wonder1 they need no longer be objects of terror4 ,though there be1 as ,kepler said1 more comets in the sky than fish in the ocean1 the encounter of the earth with a comet's tail would be like the encounter with a shadow1 and the chance of a collision with the nucleus is remote indeed4 ,we may sleep undisturbed even if a new comet is announced every month1 though it is true that here as elsewhere lie remote possibilities of evil4 ,the consideration of the unfamiliar powers certainly latent in ,nature1 such as belong to a little tremor of the planet's surface or such as was shown in that scene ,i have described1 when the comparatively insignificant effect of the few tons of dynamite was to make solid buildings unrealities1 which vanished away as quickly as magic-lantern pictures from a screen1 may help us to understand that the words of the great poet are but the possible expression of a physical fact1 and that 8the cloud-capped towers1 the gorgeous palaces1 the solemn temples10--and we with them1--may indeed conceivably some day vanish as the airy nothings at the touch of ,prospero's wand1 and without the warning to us of a single instant that the security of our ordinary lives is about to be broken4 ,we concede this1 however1 in the present case only as an abstract possibility2 for the advance of astronomical knowledge is much more likely to show that the kernel of the comet is but of the bigness of some large meteorite1 against which our air is an efficient shield1 and the chance of evil is in any case most remote1--in any case only such as may come in any hour of our lives from any quarter1 not alone from the earthquake or the comet1 but from 8the pestilence that walketh in darkness20 from the infinitely little below and within us1 as well as from the infinite powers of the universe without4 ,,viii4 ,,the ,,stars4 ,in the ,south ,kensington ,museum there is1 as everybody knows1 an immense collection of objects1 appealing to all tastes and all classes1 and we find there at the same time people belonging to the wealthy and cultivated part of society lingering over the ,louis ,seize cabinets or the old majolica1 and the artisan and his wife studying the statements as to the relative economy of baking-powders1 or admiring ,tippoo ,saib's wooden tiger4 ,there is one shelf1 however1 which seems to have some attraction common to all social grades1 for its contents appear to be of equal interest to the peer and the costermonger4 ,it is the representation of a man resolved into his chemical elements1 or rather an exhibition of the materials of which the human body is composed4 ,there is a definite amount of water1 for instance1 in our blood and tissues1 and there on the shelf are just so many gallons of water in a large vessel4 ,another jar shows the exact quantity of carbon in us2 smaller bottles contain our iron and our phosphorus in just proportion1 while others exhibit still other constituents of the body1 and the whole reposes on the shelf as if ready for the coming of a new ,frankenstein to re-create the original man and make him walk about again as we do4 ,the little vials that contain the different elements which we all bear about in small proportions are more numerous1 and they suggest1 not merely the complexity of our constitutions1 but the identity of our elements with those we have found by the spectroscope1 not alone in the sun1 but even in the distant stars and nebul2 for this wonderful instrument of the ,new ,astronomy can find the traces of poison in a stomach or analyze a star1 and its conclusions lead us to think that the ancients were nearly right when they called man a microcosm1 or little universe4 ,we have literally within our own bodies samples of the most important elements of which the great universe without is composed2 and you and ,i are not only like each other1 and brothers in humanity1 but children of the sun and stars in a more literal sense1 having bodies actually made in large part of the same things that make ,sirius and ,aldebaran4 ,they and we are near relatives4 ,illustration3 ,,fig4 #hf4--,,types ,,of ,,stellar ,,spectra4 ,but if near in kind1 we are distant relatives in another way1 for the sun1 whose remoteness we have elsewhere tried to give an idea of1 is comparatively close at hand2 quite at hand1 one may say1 for if his distance1 which we have found so enormous1 be represented by that of a man standing so close beside us that our hand may rest on his shoulder1 to obtain the proportionate distance of one of the nearest stars1 like ,sirius1 for instance1 we should need to send the man over a hundred miles away4 ,it is probably impossible to give to any one an adequate idea of the extent of the sidereal universe2 but it certainly is especially hard for the reader who has just realized with difficulty the actual immensity of the distance of the sun1 and who is next told that this distance is literally a physical point as seen from the nearest star4 ,the jaded imagination can be spurred to no higher flight1 and the facts and the enormous numbers that convey them will not be comprehended4 ,look down at one of the nests of those smallest ants1 which are made in our paths4 ,to these little people1 we may suppose1 the other side of the gravel walk is the other side of the world1 and the ant who has been as far as the gate1 a greater traveller than a man who comes back from the ,indies4 ,it is very hard to think not only of ourselves as relatively far smaller than such insects1 but that1 less than such an ant-hill is to the whole landscape1 is our solar system itself in comparison with the new prospect before us2 yet so it is4 ,all greatness and littleness are relative4 ,when the traveller from the great star ,sirius 7where1 according to the author of 8,micromegas10 all the inhabitants are proportionately tall and proportionately long-lived71 discovered our own little solar system1 and lighted on what we call the majestic planet ,saturn1 he was naturally astonished at the pettiness of everything compared with the world he had left4 ,that the ,saturnian inhabitants were in his eyes a race of mere dwarfs 7they were only a mile high1 instead of twenty-four miles like himself7 did not make them contemptible to his philosophic mind1 for he reflected that such little creatures might still think and reason2 but when he learned that these puny beings were also correspondingly short-lived1 and passed but fifteen thousand years between the cradle and the grave1 he could not but agree that this was like dying as soon as one was born1 that their life was but a span1 and their globe an atom4 ,yet it seems that when one of these very ,saturnian dwarfs came afterward with him to our own little ball1 and by the aid of a microscope discovered certain animalcul on its surface1 and even held converse with two of them1 he could not in turn make up his own mind that intelligence could inhere in such invisible insects1 till one of them 7it was an astronomer with his sextant7 measured his height to an inch1 and the other1 a divine1 expounded to him the theology of some of these mites1 according to which all the heavenly host1 including ,saturn and ,sirius itself1 were created for them4 ,do not let us hold this parable as out of place here1 for what use is it to write down a long series of figures expressing the magnitude of other worlds1 if it leave us with the old sense of the importance to creation of our own2 and what use to describe their infinite number to a human mite who reads1 and remains of the opinion that he is the object they were all created for8 ,above us are millions of suns like ours4 ,the ,milky ,way 7shown on page #bbe7 spreads among them1 vague and all-surrounding1 as a type of the infinities yet unexplored1 and of the world of nebul of which we still know so little4 ,let us say at once that it is impossible here to undertake the description of the discoveries of the ,new ,astronomy in this region1 for we can scarcely indicate the headings of the chapters which would need to be written to describe what is most important4 ,illustration3 ,,fig4 #hg4--,,the ,,milky ,,way4 7,,from ,a ,,study ,,by ,e4 ,l4 ,,trouvelot74 ,the first of these chapters 7if we treated our subjects in the order of distance7 would be one on space itself1 and our changed ideas of the void which separates us from the stars4 ,of this we will only say in passing1 that the old term 8the temperature of space0 has been nearly abrogated2 for while it used to be supposed that more than half of the heat which warmed the earth came from this mysterious 8space0 or from the stars1 it is now recognized that the earth is principally warmed only by the sun4 ,of the contents of the region between the earth and the stars1 we have1 it must be admitted1 still little but conjecture2 though perhaps that conjecture turns more than formerly to the idea that the void is not a real void1 but that it is occupied by something which1 if highly attenuated1 is none the less matter1 and something other and more than the mere metaphysical conception of a vehicle to transmit light to us4 ,of the stars themselves1 we should need another chapter to tell what has been newly learned as to their color and light1 even by the old methods1 that is1 by the eye and the telescope alone2 but if we cannot dwell on this1 we must at least refer1 however inadequately1 to what ,american astronomers are doing in this department of the ,new ,astronomy1 and first in the photometry of the stars1 which has assumed a new importance of late years1 owing to the labors carried on in this department at ,cambridge4 ,that one star differs from another star in glory we have long heard1 but our knowledge of physical things depends largely on our ability to answer the question1 8how much80 and the value of this new work lies in the accuracy and fulness of its measures2 for in this case the whole heavens visible from ,cambridge to near the southern horizon have been surveyed1 and the brightness of every naked-eye star repeatedly measured1 so that all future changes can be noted4 ,this great work has taxed the resources of a great observatory1 and its results are only to be adequately valued by other astronomers2 but ,professor ,pickering's own investigations on variable stars have a more popular interest4 ,it is surely an amazing fact that suns as large or larger than our own should seem to dwindle almost to extinction1 and regain their light within a few days or even hours2 yet the fact has long been known1 while the cause has remained a mystery4 ,a mystery1 in most cases1 it remains still2 but in some we have begun to get knowledge1 as in the well-known instance of ,algol1 the star in the head of ,medusa4 ,here it has always been thought probable that the change was due to something coming between us and the star2 but it is on this very account that the new investigation is more interesting1 as showing how much can be done on an old subject by fresh reasoning alone1 and how much valuable ore may lie in material which has already been sifted4 ,the discussion of the subject by ,professor ,pickering1 apart from its elevated aim1 has if1 in its acute analysis only1 the interest belonging to a story where the reader first sees a number of possible clews to some mystery1 and then the gradual setting aside1 one by one1 of those which are only loose ends1 and the recognition of the real ones which lead to the successful solution4 ,the skill of the novelist1 however1 is more apparent than real1 since the riddle he solves for us is one he has himself constructed1 while here the enigma is of ,nature's propounding2 and if the solution alone were given us1 the means by which it is reached would indeed seem to be inexplicable4 ,this is especially so when we remember what a point there is to work on1 for the whole system reasoned about1 though it may be larger than our own1 is at such a distance that it appears1 literally and exactly1 far smaller to the eye than the point of the finest sewing-needle2 and it is a course of accurate reasoning1 and reasoning alone1 on the character of the observed changing brightness of this point1 which has not only shown the existence of some great dark satellite1 but indicated its size1 its distance from its sun1 its time of revolution1 the inclination of its orbit1 and still more4 ,the existence of dark invisible bodies in space1 then1 is in one case at least demonstrated1 and in this instance the dark body is of enormous size2 for1 to illustrate by our own solar system1 we should probably have to represent it in imagination by a planet or swarm of planetoids hundreds of times the size of ,jupiter1 and 7it may be added7 whirling around the sun at less than a tenth the distance of ,mercury4 ,of a wholly different class of variables are those which have till lately only been known at intervals of centuries1 like that new star ,tycho saw in #aegb4 ,i infer from numerous inquiries that there is such a prevalent popular notion that the 8,star of ,bethlehem0 may be expected to show itself again at about the present time1 that perhaps ,i may be excused for answering these questions in the present connection4 ,in the first place1 the idea is not a new1 but a very old one1 going back to the time of ,tycho himself1 who disputed the alleged identity of his star with that which appeared to the shepherds at the ,nativity4 ,the evidence relied on is1 that bright stars are said to have appeared in this constellation repeatedly at intervals of from three hundred and eight to three hundred and nineteen years 7though even this is uncertain72 and as the mean of these numbers is about three hundred and fourteen1 which again is about one-fifth of #aegb 7the then number of years from the birth of ,christ71 it has been suggested1 in support of the old notion1 that the ,star of ,bethlehem might have been a variable1 shining out every three hundred and fourteen or three hundred and fifteen years1 whose fifth return would fall in with the appearance that ,tycho saw1 and whose sixth return would come in #ahhf or #ahhg4 ,this is all there is about it1 and there is nothing like evidence1 either that this was the star seen by the ,wise ,men1 or that it is to be seen again by us4 ,on the other hand1 nothing in our knowledge1 or rather in our ignorance1 authorizes us to say positively it cannot come again2 and it may be stated for the benefit of those who like to believe in its speedy return1 that if it does come1 it will make its appearance some night in the northern constellation of ,cassiopeia's chair1 the position originally determined by ,tycho at its last appearance1 being twenty-eight degrees and thirteen minutes from the pole1 and twenty-six minutes in right ascension4 ,we were speaking of these new stars as having till lately only appeared at intervals of centuries2 but it is not to be inferred that if they now appear oftener it is because there are more of them4 ,the reason is1 that there are more persons looking for them2 and the fact is recognized that1 if we have observers enough and look closely enough1 the appearance of 8new stars0 is not so very rare a phenomenon4 ,every one at all interested in such matters remembers that in #ahff a new star broke out in the ,northern ,crown so suddenly that it was shining as bright as the ,polar ,star1 where six hours before there had been nothing visible to the eve4 ,now all stars are not as large as our sun1 though some are much larger2 but there are circumstances which make it improbable that this was a small or near object1 and it is well remembered how the spectroscope showed the presence of abnormal amounts of incandescent hydrogen1 the material which is perhaps the most widely diffused in the universe 7and which is plentiful1 too1 in our own bodies71 so that there was some countenance to the popular notion that this was a world in flames4 ,we were1 at any rate1 witnessing a catastrophe which no earthly experience can give us a notion of1 in a field of action so remote that the flash of light which brought the news was unknown years on the way1 so that all this--strange but now familiar thought--occurred long before we saw it happen4 ,the star faded in a few days to invisibility to the naked eye1 though not to the telescope2 and1 in fact1 all these phenomena at present appear rather to be enormous and sudden enlargements of the light of existing bodies than the creation of absolutely new ones2 while of these 8new stars0 the examples may almost be said to be now growing numerous1 two having appeared in the last two years4 ,not to enlarge1 then1 on this chapter of photometry1 let us add1 in reference to another department of stellar astronomical work1 that the recognized master in the study of double stars the world over is not an astronomer by profession1 at the head of some national observatory in ,berlin or ,paris1 but a stenographer in the ,chicago law-courts1 ,mr4 ,w4 ,s4 ,burnham1 who1 after his day's duties1 by nightly labor1 prolonged for years with the small means at an amateur's command1 has perhaps added more to our knowledge of his special subject in ten years than all other living astronomers4 ,illustration3 ,,fig4 #hh4--,,spectra ,,of ,,stars ,,in ,,pleiades4 ,we have here only alluded to the spectroscope in its application to stellar research1 and we cannot now do more than to note the mere headlines of the chapters that should be written on it4 ,first1 there is the memorable fact that1 after reaching across the immeasurable distances1 we find that the stars are like us1--like in their ultimate elements to those found in our own sun1 our own earth1 our own bodies4 ,any fuller view of the subject than that which we here only indicate1 would begin with the evidence of this truth1 which is perhaps on the whole the most momentous our science has brought us1 and with which no familiarity should lessen our wonder1 or our sense of its deep and permanent significance4 ,next1 perhaps1 we should understand that1 invading the province of the ,old ,astronomy1 the spectroscope now tells us of the motions of these stars1 which we cannot see move1--motions in what we have always called the 8fixed0 stars1 to signify a state of fixity to the human eye1 which is such1 that to it at the close of the nineteenth century they remain in the same relative positions that they occupied when that eye first looked on them1 in some period long before the count of centuries began4 ,in perhaps the earliest and most enduring work of man's hands1 the great pyramid of ,egypt1 is a long straight shaft1 cut slopingly through the solid stone1 and pointing1 like a telescope1 to the heavens near the pole4 ,if we look through it now we see--nothing2 but when it was set up it pointed to a particular star which is no longer there4 ,that pyramid was built when the savages of ,britain saw the ,southern ,cross at night2 and the same slow change in the direction of the earth's axis1 that in thousands of years has borne that constellation to southern skies1 has carried the stone tube away from the star that it once pointed at4 ,the actual motion of the star itself1 relatively to our system1 is slower yet1--so inconceivably slow that we can hardly realize it by comparison with the duration of the longest periods of human history4 ,the stone tube was pointed at the star by the old ,egyptians1 but 8,egypt itself is now become the land of obliviousness1 and doteth4 ,her ancient civility is gone1 and her glory hath vanished as a phantasma4 ,she poreth not upon the heavens1 astronomy is dead unto her1 and knowledge maketh other cycles4 ,canopus is afar off1 ,memnon resoundeth not to the ,sun1 and ,nilus heareth strange voices40 ,in all this lapse of ages1 the star's own motion could not have so much as carried it across the mouth of the narrow tube4 ,yet a motion to or from us of this degree1 so slow that the unaided eve could not see it in thousands of years of watching1 the spectroscope1 first efficiently in the hands of the ,english astronomer1 ,dr4 ,huggins1 and later in those of ,professor ,young of ,princeton1 not only reveals at a look1 but tells us the amount and direction of it1 in a way that is as strange and unexpected1 in the view of our knowledge a generation ago1 as its revelation of the essential composition of the bodies themselves4 ,illustration3 ,,fig4 #hi4--,,spectrum ,,of ,,aldebaran4 ,illustration3 ,,fig4 #ij4--,,spectrum ,,of ,,vega4 ,again1 in showing us this composition1 it has also shown us more1 for it has enabled us to form a conjecture as to the relative ages of the stars and suns2 and this work of classifying them1 not only according to their brightness1 but each after his kind1 we may observe was begun by a countryman of our own1 ,mr4 ,rutherfurd1 who seems to have been among the first after ,fraunhofer to apply the newly-invented instrument to the stars1 and quite the first to recognize that these were1 broadly speaking1 divisible into a few leading types1 depending not on their size but on their essential nature4 ,after him ,secchi 7to whom the first conception is often wrongly attributed7 developed it1 and gave four main classes into which the stars are in this way divisible1 a classification which has been much extended by others2 while the first carefully delineated spectra were those of ,dr4 ,huggins1 who has done so much for all departments of our science that in a fuller account his name would reappear in every chapter of this ,new ,astronomy1 and than whom there is no more eminent living example of its study4 ,owing to their feeble light1 years were needed when he began his work to depict completely so full a single spectrum as that he gives of ,aldebaran1 though he has lived to see stellar spectrum photography1 whose use he first made familiar1 producing in its newest development1 which we give here1 the same result in almost as many minutes4 ,before we present this latest achievement of celestial photography1 let us employ the old method of an engraving made from eye-drawings1 once more1 to illustrate on page #bbb the distinct character of these spectra1 and their meaning4 ,in the telespectroscope1 the star is drawn out into a band of colored light1 but here we note only in black and white the lines which are seen crossing it1 the red end in these drawings being at the left1 and the violet at the right2 and we may observe of this illustration1 that though it may be criticised by the professional student1 and though it lack to the general reader the attraction of color1 or of beautiful form1 it is yet full of interest to any one who wishes to learn the meaning of the message the star's light can be made to yield through the spectroscope1 and to know how significant the differences are it indicates between one star and another1 where all look so alike to the eye4 ,first is the spectrum of a typical white or blue-white star1 ,sirius1--the very brightest star in the sky1 and which we all know4 ,the brighter part of the spectrum is a nearly continuous ribbon of color1 crossed by conspicuous1 broad1 dark lines1 exactly corresponding in place to narrower ones in our sun1 and due principally to hydrogen4 ,iron and magnesium are also indicated in this class1 but by too fine lines to be here shown4 ,sirius1 as will be presently seen1 belongs to the division of stars whose spectrum indicates a very high temperature1 and in this case1 as in what follows1 we may remark 7to use in part ,mr4 ,lockyer's words7 that one of the most important distinctions between the stars in the heavens is one not depending upon their mass or upon anything of that kind1 but upon conditions which make their spectra differ1 just in the way that in our laboratories the spectrum of one and the same body will differ at different temperatures4 ,what these absolutely are in the case of the stars1 we may not know2 but placing them in their most probable relative order1 we have taken as an instance of the second class1 or lower-temperature stage1 our own sun4 ,the impossibility of giving a just notion of its real complexity may be understood1 when we state that in the recent magnificent photographs by ,professor ,rowland1 a part alone of this spectrum occupies something like fifty times the space here given to the whole1 so that1 crowded with lines as this appears1 scarcely one in fifty of those actually visible can be given in it4 ,without trying to understand all these now1 let us notice only the identity of two or three of its principal elements with those found in other stars1 as shown by the corresponding identity of some leading lines4 ,thus1 ,c and ,f 7with others7 are known to be caused by hydrogen2 ,d1 by sodium2 b1 by magnesium2 while fainter lines are given by iron and by other substances4 ,these elements can be traced by their lines in most of the different star-spectra on this plate1 and all those named are constituents of our own frames4 ,the hydrogen lines are not quite accurately shown in the plate from which our engraving is made1 those in ,sirius1 for instance1 being really wider by comparison than they are here given2 and we may observe in this connection1 that by the particular appearance such lines wear in the spectrum itself we can obtain some notion of the mass of a star1 as well as of its chemical constitution4 ,we can compare the essential characteristics of such bodies1 then1 without reference to their apparent size1 or as though they were all equally remote2 and it is a striking thought1 that when we thus rise to an impartial contemplation of the whole stellar universe1 our sun1 whose least ray makes the whole host of stars disappear1 is found to be not only itself a star1 but by comparison a small one1--one at least which is more probably below than above the average individual of its class1 while some1 such as ,sirius1 are not impossibly hundreds of times its size4 ,then comes a third class1 such as is shown in the spectrum of the brightest star in ,orion1 looking still a little like that of our sun2 but yet more distinctively in that of the brightest star in ,hercules1 looking like a columnar or fluted structure1 and concerning which the observations of ,lockyer and others create the strong presumption1 not to say certainty1 that we have here a lower temperature still4 ,antares and other reddish stars belong to this division1 which in the very red stars passes into the fourth type1 and there are more classes and subclasses without end2 but we invite here attention particularly to the first three1 much as we might present a child1 an adult1 and an old man1 as types of the stages of human existence1 without meaning to deny that there are any number of ages between4 ,we can even say that this may be something more than a mere figure of speech1 and that a succession in age is not improbably pointed at in these types4 ,illustration3 ,,fig4 #ia4--;,,great ,,nebula ,,in ,,orion4 7,,from ,a ,,photograph ,,by ,a4 ,a4 ,,common1 ,f4 ,r4 ,s47 ,we may have considered--perhaps not without a sort of awe at the vastness of the retrospect--the past life of the worlds of our own system1 from our own globe of fluid fire as we see it by analogy in the past1 through the stages of planetary life to the actual condition of our present green earth1 and on to the stillness of the moon4 ,yet the life history of our sun1 we can hardly but admit1 is indefinitely longer than this4 ,we feel1 rather than comprehend1 the vastness of the period that separates our civilization from the early life of the world2 but what is this to the age of the sun1 which has looked on and seen its planetary children grow8 ,yet if we admit this temperature classification of the stars1 we are not far from admitting that the spectroscope is now pointing out the stages in the life of suns themselves2 suns just beginning their life of almost infinite years2 suns in the middle of their course2 suns which are growing old and casting feebler beams1--all these and many more it brings before us4 ,another division of our subject would1 with more space1 include a fuller account of that strange and most interesting development of photography which is going on even while we write2 and this is so new and so important1 that we must try to give some hint of it even in this brief summary1 for even since the first numbers of this series were written1 great advances have taken place in its application to celestial objects4 ,most of us have vague ideas about small portions of time2 so much so1 that it is rather surprising to find to how many intelligent people1 a second1 as seen on the clock face1 is its least conceivable interval4 ,yet a second has not only a beginning1 middle1 and end1 as much as a year has1 but can1 in thought at least1 be divided into just as many numbered parts as a year can4 ,without entering on a disquisition about this1 let us try to show by some familiar thing that we can at any rate not only divide a second in imagination into1 let us say1 a hundred parts1 but that we can observe distinctly what is happening in such a short time1 and make a picture of it1--a picture which shall be begun and completed while this hundredth of a second lasts4 ,every one has fallen through at least some such a little distance as comes in jumping from a chair to the floor1 and most of us1 it is safe to say1 have a familiar impression of the fact that it takes1 at any rate1 less than a second in such a case from the time the foot leaves its first support till it touches the ground4 ,plainly1 however large or small the fall may be1 each fraction of an inch of it must be passed through in succession1 and if we suppose the space to be divided1 for instance1 into a hundred parts1 we must divide in thought the second into at least as many1 since each little successive space was traversed in its own little interval of time1 and the whole together did not make a second4 ,we can even1 as a matter of fact1 very easily calculate the time that it will take anything which has already fallen1 let us say one foot1 to fall an inch more2 and we find this1 in the supposed instance1 to be almost exactly one one-hundredth of a second4 ,on page #bdc is a reproduction of a photograph from ,nature1 of a man falling freely through the air4 ,he has dropped from the grasp of the man above him1 and has already fallen through some small distance1--a foot or so4 ,if we suppose it to be a foot1 since we can see that the man's features are not blurred1 as they would undoubtedly have been had he moved even much less than an inch while this picture was being taken1 it follows1 from what has been said1 that the making of the whole picture--landscape1 spectators1 and all--occupied not over one one-hundredth of a second4 ,we have given this view of 8the falling man0 because1 rightly understood1 it thus carries internal evidence of the limit of time in which it could have been made2 and this will serve as an introduction to another picture1 where probably no one will dispute that the time was still shorter1 but where we cannot give the same kind of evidence of the fact4 8,quick as lightning0 is our common simile for anything occupying1 to ordinary sense1 no time at all4 ,exact measurements show that the electric spark does occupy a time1 which is almost inconceivably small1 and of which we can only say here that the one one-hundredth of a second we have just been considering is a long period by comparison with the duration of the brightest portion of the light4 ,illustration3 ,,fig4 #ib4--;,a ,,falling ,,man4 ,on page #bde we have the photograph of a flash of lightning 7which proves to be several simultaneous flashes71 taken last ,july from a point on the ,connecticut coast1 and showing not only the vivid zigzag streaks of the lightning itself1 but something of the distant sea view1 and the masts of the coast survey schooner 8,palinurus0 in the foreground1 relieved against the sky4 ,we are here concerned with this interesting autograph of the lightning1 only as an illustration of our subject1 and as proving the almost infinite sensitiveness of the recent photographic processes2 for there seems to be no limit to the briefness of time in which1 these can so act in some degree1 whether the light be bright or faint1 and no known limit to the briefness of time required for them to act effectively if the light be bright enough4 ,what has just preceded will now help us to understand how it is that photography also succeeds so well in the incomparably fainter objects we are about to consider1 and which have been produced not by short but by long exposures4 ,we have just seen how sensitive the modern plate is1 and we are next to notice a new and very important point in which photographic action in general differs remarkably from that of the eye4 ,seeing may be described1 not wholly inaptly1 as the recognition of a series of brief successive photographs1 taken by the optic lens on the retina2 but the important difference between seeing and photographing1 which we now ask attention to1 is this3 ,when the eye looks at a faint object1 such as the spectrum of a star1 or at the still fainter nebula1 this1 as we know1 appears no brighter at the end of half an hour than at the end of the first half-second4 ,in other words1 after a brief fraction of a second1 the visual effect does not sensibly accumulate4 ,but in the action of the photograph1 on the contrary1 the effect does accumulate1 and in the case of a weak light accumulates indefinitely4 ,it is owing to this precious property1 that supposing 7for illustration merely7 the lightning flash to have occupied the one-thousandth part of a second in impressing itself on the plate1 to get a nearly similar effect from a continuous light one thousand times weaker1 we have only to expose the date a thousand times as long1 that is1 for one second2 while from a light a million times weaker we should get the same result by exposing it a million times as long1 that is1 for a thousand seconds4 ,and now that we come to the stars1 whose spectra occupy minutes in taking1 what we just considered will help us to understand how we can advantageously thus pass from a thousandth of a second or less1 to one thousand seconds or even more1 and how we can even1--given time enough1--conceivably1 be able to photograph what the eye cannot see at all4 ,illustration3 ,,fig4 #ic4--;,a ,,flash ,,of ,,lightning4 7,,from ,a ,,photograph ,,by ,,dr4 ,h4 ,g4 ,,piffard47 ,we have on page #bca a photograph quite recently taken at ,cambridge from a group of stars 7the ,pleiades7 passing by the telescope4 ,every star is caught as it goes1 and presented1 not in its ordinary appearance to the eye1 but by its spectrum4 ,there is a general resemblance in these spectra from the same cluster2 while in other cases the spectra are of all types and kinds1 the essential distinction between individuals alike to the eve1 being more strikingly shown1 as stars apparently far away from one another are seen to have a common nature1 and stars looking close together 7but which may be merely in line1 and really far apart7 have often no resemblance2 and so the whole procession passes through the field of view1 each individual leaving its own description4 ,this self-description will be better seen in the remarkable photographs of the spectra of ,vega and ,aldebaran1 which are reproduced on page #bce from the originals by a process independent of the graver4 ,they were obtained on the night of ,november #i1 #ahhf1 at ,cambridge1 as a part of the work pursued by ,professor ,pickering1 with means which have been given from fitting hands1 thus to form a memorial of the late ,dr4 ,henry ,draper4 ,we are obliged to the source indicated1 then1 for the ability to show the reader here the latest1 and as yet inedited1 results in this direction2 and they are such as fully to justify the remark made above1 that minutes1 by this new process1 take the place of years of work by the most skilful astronomer's eye and hand4 ,the spectrum of ,vega 7,alpha ,lyr7 is marked only by a few strong lines1 due chiefly to hydrogen1 because these are all there are to be seen in a star of its class4 ,aldebaran 7the bright star in ,taurus71 on the contrary1 here announces itself as belonging to the family of our own sun1 a probably later type1 and distinguished by solar-like lines in its spectrum1 which may be counted in the original photograph to the number of over two hundred4 ,there is necessarily some loss in the printed reproduction2 but is it not a wonderful thing1 to be able to look up1 as the reader may do1 to ,aldebaran in the sky1 and then down upon the page before us1 knowing that that remote1 trembling speck of light has by one of the latest developments of the ,new ,astronomy been made1 without the intervention of the graver's hand1 to write its own autograph record on the page before him8 ,in the department of nebular astronomy1 photography has worked an equal change4 ,the writer well remembers the weeks he has himself spent in drawing or attempting to draw nebul1--things often so ghost-like as to disappear from view every time the eye turned from the white paper1 and only to be seen again when it had recovered its sensitiveness by gazing into the darkness4 ,the labors of weeks were1 literally1 only represented by what looked like a stain on the paper2 and no two observers1 however careful1 could be sure that the change between two drawings of a nebula at different dates was due to an alteration in the thing itself1 or in the eye or hand of the observer1 though unfortunately for the same reason it is impossible fully to render the nebulous effect of the photograph in engraving4 ,we cannot with our best efforts1 then1 do full justice to the admirable one of ,orion1 on page #bci1 which we owe to the particular kindness of ,mr4 ,common1 of ,ealing1 ,england1 whose work in this field is as yet unequalled4 ,the original enlargement measures nearly two square feet in area1 with fine definition4 ,it is taken by thirty-nine minutes' exposure1 and its character can only be indicated here2 for it is not too much to say here of this original also1 that as many years of the life of the most skilled artist could not produce so trustworthy a record of this wonder4 ,the writer remembers the interest with which he heard ,dr4 ,draper1 not long before his lamented death1 speak of the almost incredible sensitiveness of these most recent photographic processes1 and his belief that we were fast approaching the time when we should photograph what we could not even see4 ,that time has now arrived4 ,at ,cambridge1 in ,massachusetts1 and at the ,paris ,observatory1 by taking advantage of the cumulative action we have referred to1 and by long exposures1 photographs have recently been taken showing stars absolutely invisible to the telescope1 and enabling us to discover faint nebul whose previous existence had not been suspected2 and when we consider that an hour's exposure of a plate1 now not only secures a fuller star-chart than years of an astronomer's labor1 but a more exact one1 that the art is every month advancing perceptibly over the last1 and that it is already1 as we may say1 not only making pictures of what we see1 but of what we cannot see even with the telescope1--we have before us a prospect whose possibilities no further words are needed to suggest4 ,we have now1 not described1 but only mentioned1 some division of the labors of the ,new ,astronomy in its photometric1 spectroscopic1 and photographic stellar researches1 on each of which as many books1 rather than chapters1 might be written1 to give only what is novel and of current interest4 ,but these are themselves but a part of the modern work that has overturned or modified almost every conception about the stellar universe which was familiar to the last generation1 or which perhaps we were taught in our own youth4 99 99 99 99 99 ,in considering the results to be drawn from this glance we have taken at some facts of modern observation1 if it be asked1 not only what the facts are1 but what lessons the facts themselves have to teach1 there is more than one answer1 for the moral of a story depends on the one who draws it1 and we may look on our story of the heavens from the point of view either of our own importance or of our own insignificance4 ,in the one case we behold the universe as a sort of reflex of our own selves1 mirroring in vast proportions of time and space our own destiny2 and even from this standpoint1 one of the lessons of our subject is surely that there is no permanence in any created thing4 ,when primitive man learned that with lapsing years the oak withered and the very rock decayed1 more slowly but as surely as himself1 he looked up to the stars as the types of contrast to the change he shared1 and fondly deemed them eternal2 but now we have found change there1 and that probably the star clusters and the nebul1 even if clouds of suns and worlds1 are fixed only by comparison with our own brief years1 and1 tried by the terms of their own long existence1 are fleeting like ourselves4 8,we have often witnessed the formation of a cloud in a serene sky4 ,a hazy point barely perceptible--a little wreath of mist increases in volume and becomes darker and denser1 until it obscures a large portion of the heavens4 ,it throws itself into fantastic shapes1 it gathers a glory from the sun1 is borne onward by the wind1 and as it gradually came1 so1 perhaps1 it gradually disappears1 melting away in the untroubled air4 ,but the universe is nothing more than such a cloud1--a cloud of suns and worlds4 ,supremely grand though it may seem to us1 to the infinite and eternal intellect it is no more than a fleeting mist4 ,if there be a succession of worlds in infinite space1 there is also a succession of worlds in infinite time4 ,as one after another cloud replaces clouds in the skies1 so this starry system1 the universe1 is the successor of countless others that have preceded it1--the predecessor of countless others that will follow40 ,these impressions are strengthened rather than weakened when we come back from the outer universe to our own little solar system2 for every process which we know1 tends to the dissipation1 or rather the degradation1 of heat1 and seems to point1 in our present knowledge1 to the final decay and extinction of the light of the world4 ,in the words of one of the most eminent living students of our subject1 8,the candle of the sun is burning down1 and1 as far as we can see1 must at last reach the socket4 ,then will begin a total eclipse which will have no end4 #8,dies ir1 dies illa1 ,solvet sclum in favilla4'0 ,yet though it may well be that the fact itself here is true1 it is possible that we draw the moral to it1 unawares1 from an unacknowledged satisfaction in the idea of the vastness of the funeral pyre provided for such beings as ourselves1 and that it is pride1 after all1 which suggests the thought that when the sun of the human race sets1 the universe will be left tenantless1 as a body from which the soul has fled4 ,can we not bring ourselves to admit that there may be something higher than man and more enduring than frail humanity1 in some sphere in which our universe1 conditioned as it is in space and time1 is itself embraced2 and so distrust the conclusions of man's reason where they seem to flatter his pride8 ,may we not receive even the teachings of science1 as to the 8,laws of ,nature10 with the constant memory that all we know1 even from science itself1 depends on our very limited sensations1 our very limited experience1 and our still more limited power of conceiving anything for which this experience has not prepared us8 99 99 99 99 99 ,i have read somewhere a story about a race of ephemeral insects who live but an hour4 ,to those who are born in the early morning the sunrise is the time of youth4 ,they die of old age while his beams are yet gathering force1 and only their descendants live on to midday2 while it is another race which sees the sun decline1 from that which saw him rise4 ,imagine the sun about to set1 and the whole nation of mites gathered under the shadow of some mushroom 7to them ancient as the sun itself7 to hear what their wisest philosopher has to say of the gloomy prospect4 ,if ,i remember aright1 he first told them that1 incredible as it might seem1 there was not only a time in the world's youth when the mushroom itself was young1 but that the sun in those early ages was in the eastern1 not in the western1 sky4 ,since then1 he explained1 the eyes of scientific ephemera had followed it1 and established by induction from vast experience the great 8,law of ,nature10 that it moved only westward2 and he showed that since it was now nearing the western horizon1 science herself pointed to the conclusion that it was about to disappear forever1 together with the great race of ephemera for whom it was created4 ,what his hearers thought of this discourse ,i do not remember1 but ,i have heard that the sun rose again the next morning4 ,,index4 ,abbe1 ,professor1 #ef4 ,actinism1 #ga4 ,adams1 ,professor1 #aie4 ,africa1 #aaf4 ,ages1 stellar1 #bch4 ,air3 dancing1 #ag2 a medium1 #cc2 continuous1 #agf2 rarefied1 #agi2 motes1 #aha2 nimble1 #aia4 7,see ,atmosphere47 ,airless ,mountains1 #afj4 ,air-wave1 #ahe4 ,aitken's ,researches1 #aha4 ,alaska1 #ch4 ,aldebaran1 #bbb1 #bce1 #bcf1 #bdf4 ,algot1 #bbh4 ,allegheny ,observatory1 #ag1 #ai1 #hd1 #hf4 7,see ,langley47 ,alphonsus ,ring-plain1 #aef4 ,alps1 #ci1 #adh1 #aea1 #afg1 #aha4 7,see ,apennines1 ,lunar47 ,american ,astronomers1 #bbg4 ,american ,continents1 #bj1 #ba1 #ca4 7,see ,south47 ,andalusia1 #ec4 ,animalcul1 #bbd4 ,animals3 food1 #gd2 fright1 #db4 7,see ,dog47 ,antares1 #bch4 ,ants1 #bbc4 7,see ,insects47 ,apennines1 #aea1 #aec1 #aee1 #afj1 #afg4 7,see ,alps1 ,lunar47 ,apples1 #aga4 ,arab ,traditions1 #aid4 7,see ,moslem47 ,arago1 quoted1 #da1 #db4 ,archimedes1 #id4 ,archimedes ,crater1 #aea-aec1 #aee4 ,arctic ,cold1 #aei4 ,arctic ,pole1 #if4 ,arcturus1 #bjh1 #baa4 ,aristillus ,crater1 #aea4 ,aristotelian ,philosophy1 #h4 ,arzachel1 #aef1 #afa4 ,asteroids1 #abh4 ,astrology1 #abg4 ,astronomers and ,priests1 #a-c4 7,see ,american1 ,new1 ,old47 ,astronomical ,day1 #he1 #hf4 ,atmosphere1 #acf1 #ahj2 as a shield1 #baf1 #bbj4 7,see ,air47 ,atolls1 #aeb4 ,auger1 simile1 #ca4 ,aurora ,borealis1 #ce1 #fg1 #bab4 ,autolycus ,crater1 #aea4 ,axis1 #i1 #aj4 ,babel1 #if4 ,bain ,telegraph1 #hh4 ,balloons1 #agf4 ,bees1 #abd4 7,see ,insects47 ,berkeley's ,theory1 #gj4 ,berlin ,observatory1 #bcc4 ,bernires's ,lens1 #ajc4 ,bessemer ,steel1 #ajd-ajh4 ,birds1 #agb1 #aif1 #aig4 7,see ,animals47 ,black ,hole1 #gc4 ,bond1 ,professor1 #bjd4 ,boston1 ,mass41 #hh1 #acb4 ,bothkamp1 observations at1 #ff4 ,breadstuffs1 #gh1 #gi4 7,see ,grain1 ,sun-spots1 ,wheat47 ,bridges1 #bj1 #fh4 ,britain1 ,ancient1 #a1 #bcd4 7,see ,england47 ,british ,isles1 #ad1 #be4 ,brocken ,spectre1 #ee4 ,brothers1 ,mr41 #ej4 ,bubbles1 #afh4 ,buffer1 the air as a1 #baf1 #bbj4 ,bunsen's ,researches1 #ab4 ,burnham1 ,w4 ,s41 #bcc4 ,burning-glasses1 #ajb-ajd4 ,burning ,heat1 #afj1 #afc4 ,cactus1 #ad1 #bd4 ,calcutta1 #gc4 ,california1 #aea1 #ahj4 ,cambric ,needle 7q4 v471 experiment1 #acb4 ,cambridge ,observations1 #bbg1 #bde-bdg4 ,camera ,obscura1 #fc4 ,campanus ,crater1 #afc1 #afe4 ,candle1 simile1 #ci4 ,cannon-ball1 #e1 #ch1 #da1 #ih1 #ace1 #ahf1 #baa4 ,canopus1 #bcd4 ,carbon1 #gb1 #gc1 #ajg1 #bba4 ,carbonic-acid ,gas1 #bai4 ,carpenter's ,studio1 #adj4 ,carrington's ,work1 #gi1 #hg4 ,carthage1 #aaf4 ,cassini1 #db4 ,cassiopeia1 #bbi4 ,cataclysm1 #cj4 ,centimetres1 #ic4 ,chacornac's ,drawing1 #cc4 ,chambers1 on sun-spots1 #hj4 ,charleston ,earthquake 7q4 v471 #db4 ,chemical ,elements1 #bba1 #bbc4 ,cherry-stone1 comparison1 #aif4 ,chicago3 great fire1 #acd2 astronomer1 #bcc4 ,china3 lens1 #ajc1 #ajd2 soil1 #ahj4 ,chlorophyl1 #gc4 ,chocolate1 simile1 #ajg4 ,cholera1 #hj4 ,chromosphere1 #g2 clouds1 #fb2 forms1 #fd-fh4 ,cinders1 #aga4 ,clark's ,glasses1 #abc4 ,cliffs1 #afd4 ,clock1 #ace4 ,cloud-ocean1 #agi4 ,clouds3 cirrous1 #bg1 #bh2 beautiful1 #ed2 and rain1 #aaa2 formed1 #bdi4 ,coal-beds1 #aae4 ,coal3 energy1 #gc-ge1 #aaa2 destroyed1 #ig2 wasted1 #aja2 stock1 #aab4 ,cobweb1 simile1 #bf4 ,cold3 and eclipses1 #dj2 in planets1 #acf4 ,colorado1 #ej4 ,colors3 in eclipses 7q4 v471 #fe2 mental1 #gj1 #ga2 in ,jupiter 7q4 v471 #abg2 in moon 7q4 v471 #afh2 in stars 7q4 v471 #bbg2 spectrum 7q4 v471 #bcf4 ,comet-hunters1 #bjd1 #bjg4 ,comets3 chapter1 #aii-bbj2 ,donati's1 #bja1 #bjd1 #bje1 #bjg1 #bji1 #bag2 one part1 #bjc2 parts and name1 #bjh2 tail 7q4 v471 #bjh1 #baa2 diameter and parts1 #baf2 spectroscope1 elements1 dread1 #bai2 numerous1 stone1 #bai1 #bbj2 kernel1 #bbj2 7#aheh71 #bac-baf2 7#ahff71 #bjj4 ,common1 ,a4 ,a41 #bci1 #bdg4 ,compass1 #hf4 ,connecticut ,observations1 #ahf1 #bdb4 ,converter1 #ajd-ajh4 ,coral1 #aea4 ,corn1 #aaa4 7,see ,grain47 ,corona1 #g1 #cf1 #cg1 #dj1 #da1 #dc1 #de-eb1 #ee1 #ef1 #ei1 #fj-fb4 ,cotton-mill1 #gd4 ,counting1 #id4 ,cracks1 celestial1 #afc4 ,craters1 #afd4 7,see special names47 ,crystalline ,structure1 #d1 #bc-bg4 ,cyclones1 #bd1 #ca1 #cb1 #fh4 ,decay1 #bdh1 #bdi4 ,delambre's ,history1 #bjg4 ,de la ,rue's ,engraving1 #abe4 ,delfthaven1 #e4 ,denning's ,theory1 #aig4 ,diamonds1 melted1 #ajc4 ,dies ,ir1 #bdi4 ,dipper1 #bjg1 #bjh4 7,see ,great ,bear1 ,polar47 ,diurnal ,oscillation1 #hg4 ,dog1 anecdote of1 #db4 7,see ,animals47 ,donati1 #bja1 #bjd1 #bje1 #bjg1 #bji1 #bac1 #bag4 7,see ,comets47 ,double ,stars1 #bcc4 ,draper1 ,professor ,henry1 #abh1 #bdf1 #bdg4 ,ducks1 noise1 #ahh4 ,dust1 #cd1 #ajj1 #aja1 #ajb1 #aje1 #aig4 ,dynamite1 #ahb1 #ahe1 #bbj4 ,earth3 relations1 #c1 #d2 description difficult1 #f2 temperature 7q4 v471 #cd1 #aja2 a string of earths1 #if2 stars like1 #aah2 seen from outside1 #acc-ace2 craters1 #adh4 ,earthquakes1 #bbj4 7,see ,charleston47 ,earth-shine1 #afg1 #agb4 ,eclipses3 total1 #g1 #cg2 screen1 #cf2 three1 #ci1 #ee2 partial1 #dj2 singular gloom1 #ci-dc2 causing fright1 #dc2 colors 7q4 v471 #dh1 #ef1 #fa1 #fe1 #ff2 7#ahdb71 #da2 7#aheg71 #dh2 7#ahfi71 #ci1 #dj2 7#ahgj71 #dd1 #fa2 7#ahga71 #ej1 #ff1 #fh2 7#ahgh71 #ch1 #ej1 #eg1 #eh4 7,see ,total47 ,egypt1 #aaf1 #bcd4 7,see ,pyramids47 ,electricity1 #ac1 #ge1 #gf4 ,electric ,light1 #g4 ,electric ,spark1 #bdb4 7,see ,lightning47 ,electric ,storm1 #hd1 #he1 #hh4 ,elizabeth1 ,queen1 #aae4 ,engine-power1 #ih1 #aaa4 ,england3 fleets1 #b2 coal1 #aae4 7,see ,britain1 ,london47 ,engraving1 #ag4 ,enigma1 #bbh4 ,ephemera1 #bej1 #bea4 ,equatorial ,landscape1 #ac1 #ag1 #ah1 #dg4 ,equatorial ,telescope1 #abb4 ,ericsson3 engravings1 #aab1 #aac2 discoveries1 #afc4 ,eruptive ,promontories1 #ff-fh4 ,etna1 #afd1 #aha4 ,europe1 size1 #be4 ,evolution1 planetary1 #aci4 ,explosive ,forces1 #ahb-aid4 ,eye1 #ga1 #bbg4 ,eye-pieces1 #dg1 #fc4 ,fabricius's ,observations1 #h4 ,fact and ,fancy1 #age4 ,factory1 #gc4 ,facul1 #cb1 #cc4 ,falling1 #bdb1 #bdc4 ,falling ,stars1 #aic4 7,see ,meteors1 ,shooting47 ,faraday1 ,michael1 #gf4 ,fault1 technical term1 #aef4 ,faust1 #aci4 ,faye3 theory1 #bi-cb2 on ,comets' ,tails1 #bab4 ,fern-like ,forms1 #be1 #bf4 ,filaments1 #be-bg1 #cj1 #ee1 #ef1 #fe1 #ff1 #fh4 ,fire1 in sun 7q4 v471 #ib4 7,see ,flames1 ,heat47 ,fixed ,stars1 #bcc4 ,flame-like ,appearances1 #bc1 #bd4 ,flames1 #fe1 #ff1 #fi1 #ahe4 ,flashes1 #ahi1 #aie4 ,flax1 #aaa4 ,flowers1 color 7q4 v471 #gj4 7,see ,rose1 ,plants47 ,foliage-forms1 #cb4 ,fontenelle's ,story1 #acc4 ,forbes's ,observations1 #ch1 #ci4 ,frankenstein1 #bba4 ,franklin's ,discoveries1 #gf4 ,fraunhofer ,studies1 #bce4 ,french ,institute1 #ahf4 ,frost-crystals 7q4 v471 #bc4 ,furnaces1 #aja4 ,galileo1 #h1 #aba-abc1 #aci1 #adj4 ,gas3 glowing1 #dd2 in sun1 #fj4 ,gas-jets1 #dj1 #fa1 #fh1 #hh4 ,gassendi's ,view1 #agb1 #agc4 ,gelinck's ,observations1 #hj4 ,geminids1 #aif4 ,genii1 #aic4 ,geographers and ,geologists1 #acc4 ,glare1 #ad1 #ah1 #fb-fd4 ,glass3 spun1 #bf2 globe1 #ade4 ,glow-worms1 #g1 #aag4 ,good ,hope ,observations1 #hj4 ,gould's ,researches1 #hj4 ,grain1 prices1 #gg1 #hj1 #hg4 7,see ,corn1 ,sun-spots1 ,wheat47 ,gramarye1 #ib4 ,grass-blades1 #ff1 #gb4 ,grasses1 #bf4 ,gravitation1 #gb1 #bjc2 negative1 #bae4 ,great ,bear1 #bjg4 7,see ,dipper1 ,polar47 ,green's ,maps1 #acj4 ,greenwich ,observatory1 #b1 #ha1 #hb1 #hd1 #he1 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,humming-bird1 #gj4 ,hunt1 ,professor1 #acf1 #bai4 ,hydrogen1 #fh1 #ii1 #bcg4 ,ibrahim1 ,king1 story1 #aid1 #aie4 ,ice3 melted1 #ie1 #if2 never melted1 #afc1 #afd4 ,imbrian ,sea1 #aea4 ,insects1 #bbd1 #bej4 7,see ,ants1 ,bees47 ,iron3 melting1 #ai1 #ajg2 appearance of cold1 #be2 in sun1 #bh2 in man1 #bba2 in stars1 #bcf1 #bcg4 7,see ,steel47 ,ironstone1 #ahh4 ,ivy1 #aae4 ,janssen's ,observations1 #fa4 ,jevons1 ,professor1 #hj4 ,joseph in ,egypt1 #ij4 ,jumping1 #bda1 #bdb4 ,jupiter1 #gi1 #aah1 #abd1 #abg-abi1 #aef1 #ahe1 #bbi4 ,kensington ,museum1 #bba4 ,kepler1 on ,comets1 #bai4 ,kernels1 #bbj4 ,kew1 #hh4 ,kirchoff's ,researches1 #ab4 ,krakatao1 #aha1 #ahe1 #ahf4 ,la ,harpe1 quoted1 #bjg4 ,landscape1 #afi4 ,langley1 ,prof4 ,s4 ,p43 drawings1 #ae1 #af1 #ah1 #ai1 #ba1 #bb1 #be1 #bh1 #cj2 note-book1 #bd2 expedition1 #ahj2 study of ,reflection1 #baf4 7,see ,allegheny1 ,pittsburg47 ,latent ,power1 #bbj4 ,laws of ,nature1 #bej1 #bea4 ,leaf-like ,appearances1 #bc4 7,see ,willow47 ,lenses1 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