,transcriber's ,notes3 ,underscores 80 before and after a word or phrase indicate italics in the original text4 ,small capitals have been converted to ,,solid capitals4 ,illustrations and footnotes have been moved so they do not break up paragraphs4 ,typographical and punctuation errors have been silently corrected4 ,,stars ,,of ,,the ,,southern ,,skies ,illustration3 ,,southern ,,hemisphere ,,stars ,,of ,,the ,,southern ,,skies ,,by ,m4 ,a4 ,,orr 7,,mrs4 ,,john ,,evershed7 ,,author ,,of 8,,an ,,easy ,,guide ,,to ,,southern ,,stars0 ,,and 8,,dante ,,and ,,the ,,early ,,astronomers0 8,all experience is an arch wherethrough ,we glimpse the untravelled world whose margin fades ,forever and forever40 ,,with ,,illustrations ,,longmans1 ,,green ,,and ,,co4 #ci ,,paternoster ,,row1 ,,london ,,fourth ,,avenue #cj,,th ,,street1 ,,new ,,york ,,bombay1 ,,calcutta1 ,,and ,,madras #aiae ,all rights reserved ,,to ,,miss ,,mary ,,proctor ,,contents ,,chap4 ,,page ,,the ,,greek ,,letters x ,,introduction xi ,i4 ,,the ,,constellations ,,of ,,the ,,south3 ,,modern ,,groups #a ,,ii4 ,,the ,,constellations ,,of ,,the ,,south3 ,,ancient ,,groups #f ,,iii4 ,,the ,,ten ,,brightest ,,stars ,,of ,,the ,,southern ,,hemisphere #ae ,,iv4 ,,stars ,,of ,,different ,,ages #bc ,v4 ,,some ,,near ,,neighbours #cb ,,vi4 ,,double ,,and ,,multiple ,,stars #ce ,,vii4 ,,the ,,astonishing ,,star1 ,,eta ,,arg,s #dj ,,viii4 ,,mira1 ,,the ,,wonderful ,,star #df ,,ix4 ,,eclipsing ,,stars #ea ,x4 ,,short-,,period ,,variable ,,stars #ed ,,xi4 ,,irregular ,,and ,,doubtful ,,variables #eg ,,xii4 ,,star-,,clusters #ei ,,xiii4 ,,globular ,,star-,,clusters #ff ,,xiv4 ,,nebulae #gb ,,xv4 ,,other ,,types ,,of ,,nebulae #hj ,,xvi4 ,,the ,,clouds ,,of ,,magellan #he ,,xvii4 ,,the ,,milky ,,way #hh ,,list ,,of ,,illustrations ,,page ,,map ,,of ,,the ,,southern ,,hemisphere to face ,title ,,the ,,old ,,constellation ,,figures ,,of ,,the ,,southern ,,hemisphere to face page #f ,,the ,,archer page #aa ,from a ,babylonian ,boundary ,stone now in the ,british ,museum ,,the ,,star-,,cluster1 #dg ,,toucani to face page #fh ,from ,sir ,john ,herschel's drawing ,,the ,,milky ,,way ,,in ,,scorpio1 ,,lupus1 ,,and ,,ara to face page #hh ,photographed at ,hanover1 ,cape ,colony1 by ,bailey and ,schultz ,,the ,,greek ,,letters ,alpha ,nu ,beta ,xi ,gamma ,omicron ,delta ,pi ,epsilon ,rho ,zeta ,sigma ,eta ,tau ,theta ,upsilon ,iota ,phi ,kappa ,chi ,lambda ,psi ,mu ,omega ,,introduction ,this book is for those who have learned or are learning to recognise the southern constellations1 but have not read much about astronomy1 and have only an opera-glass or small telescope1 or no instrument but their own eyes1 for examining the stars4 ,i assume that they have studied some simple guide to the constellations like ,proctor's1 or my ,southern ,stars1 and that they would like to know something more about the stars they are looking at--how far off they are1 how large1 if they remain always the same1 and if there is any connection between the different parts of this immense universe of stars and nebulae4 ,i hope that the book will be useful to teachers and parents1 helping them to answer some of the searching questions children put1 and to teach some of the facts of astronomy in the most vivid and unforgettable way--viz4 in connection with special stars and nebulae which are at the moment being admired4 ,if an opera-glass or field-glass can be put into the children's hands1 so that they themselves can see a faint white spot turn into a lovely cluster of stars1 it will give them a share in the thrill of discovery1 and help them to understand what large telescopes can show4 ,a map of the southern hemisphere is here given for ready reference1 but it would be well to possess a good atlas which gives the letters and numbers assigned to all bright stars and shows the positions of the brightest star-clusters and nebulae4 ,norton's ,star-,atlas and ,telescopic ,handbook is an excellent one1 small enough to be handy1 yet complete as far as it goes1 and up to date1 clear1 and convenient to use4#a #a ,published at #es4 by ,gall ,inglis1 ,edinburgh and ,london4 ,my intention is to treat specially of stars and nebulae visible in southern countries1 so ,i have confined myself almost entirely to those of the southern hemisphere1 though of course many which are north of the celestial equator can be seen also4 ,my readers will find that the southern hemisphere possesses the most beautiful part of the ,milky ,way1 the two brightest stars in the sky1 the finest coloured star-cluster and the largest globular cluster1 the brightest double star1 the nearest of the stars1 and the brightest of the large gaseous nebulae4 ,let us add that the southern hemisphere has been less studied than the north1 and therefore there is an even wider field for amateur workers4 ,stars of the ,southern ,skies ,i ,,the ,,constellations ,,of ,,the ,,south3 ,,modern ,,groups ,when we speak of the southern constellations1 everyone thinks of the ,southern ,cross1 and every traveller coming south for the first time is eager to see it4 ,some are disappointed because it is small and irregular1 but it is very brilliant1 and lies in an extremely rich region of the ,milky ,way4 ,very beautiful1 too1 is the way in which it is seen rising on its side and gradually becoming upright as it reaches its greatest height above the horizon1 then sloping again as it glides westward4 ,the ,cross seems to have been first so named by the ,spanish explorer ,amerigo ,vespucci1 at the beginning of the sixteenth century1 and it was also described in letters by the ,florentine ,andrea ,corsali1 who says it is so beautiful that in his opinion no other constellation in the sky is worthy to be compared with it4 ,some think1 however1 that the stars had already been recognised as forming a ,cross as early as the thirteenth century1 because ,dante in his ,purgatory speaks of four stars which glorified the southern sky2 but he does not say they were in the form of a cross1 and he tells us that they had never been seen before by mortal man except by our first parents1 whose original dwelling-place he sets in the southern hemisphere4 ,this negatives the suggestion that some traveller had described them to him4 ,about the same time as the ,cross1 other groups were named by sailors and travellers in the part of the sky round about the south pole1 for this region had been left a blank by the framers of the ancient constellations1 doubtless because they lived too far north to see it4 ,some students of astronomy in the ,middle ,ages concluded that there really were no stars in this part1 and ,ristoro of ,arezzo gravely argued that this proved the absence of any land further south than ,india and ,ethiopia2 for where there are no stars to pour down influences on the earth no animals can live1 and therefore no vegetation is needed for their food1 and no land for it to grow on4 ,the new constellations were mostly named after strange birds and fishes seen by explorers in their southern voyages1 and they were admitted to scientific astronomy by ,bayer1 who made a map of the skies in #afjd4 ,he also introduced the plan of naming each star in a constellation by a ,greek letter1 the brightest of each constellation usually being called ,alpha1 the next brightest ,beta1 and so on4 ,one of these constellations is ,grus1 the ,crane 7originally called the ,flamingo71 and it is convenient to be familiar with it1 because from it we may easily identify several others4 ,the chief stars of ,grus form a striking curve with a bright star close beside it4 ,this bright star is ,alpha ,gruis1 and the brightest in the curve is ,beta4 ,a line through ,alpha and ,beta leads in one direction to the brightest star of the ,phoenix1 in the other direction to the brightest of the ,indian2 a line through ,alpha and the little naked-eye double ,delta takes one to ,pavo1 the ,peacock2 a line through ,gamma 7at one end of the curve7 and ,alpha goes to the brightest star in the ,toucan4 ,and these are all the modern groups containing bright stars except the ,southern ,triangle1 near the ,pointers to the ,cross 7see p4 #f71 and ,columba1 the ,dove1 not far from ,sirius1 each of which has one star brighter than third magnitude4#b ,we may1 however1 also notice ,alpha ,hydri1 the brightest star in the small ,water-,snake1 close to the bright star ,achernar1 and ,alpha ,dorads1 the brightest of the ,sword-,fish1 between ,canopus and ,achernar4 #b ,stars are classified by astronomers in 8magnitudes10 i4e4 degrees of brightness1 those of first magnitude being the brightest4 ,stars below sixth magnitude cannot be seen with the naked eye4 ,in the eighteenth century the ,french astronomer ,lacaille1 who did much excellent work in the southern hemisphere with a tiny telescope of only half an inch aperture1 had the unhappy idea of filling up the spaces still left empty with scientific instruments4 ,it is easy to make ,birds of ,paradise and ,flying ,fishes out of the stars1 but such things as telescopes1 easels1 and sextants do not lend themselves to irregular groups1 and they are very much out of place among the mythical beasts and heroes which we are accustomed to see on our star-maps4 ,fortunately the beginner need not learn to recognise these intruders1 for there are no bright stars in them1 although there are many interesting objects for telescopic study4 ,we need only note that ,octans1 the ,octant1 occupies the region in which the south pole is situated1 which is quite bare of bright stars4 ,the pole itself may be found by drawing a line from head to foot of the ,cross and carrying it on about four times as far again2 or if the ,cross is invisible1 the pole may be found near the middle of a line from ,canopus to ,alpha ,pavonis4 ,,ii ,,the ,,constellations ,,of ,,the ,,south3 ,,ancient ,,groups ,let us turn once more to the ,southern ,cross to find the ancient constellations4 ,it is both ancient and modern itself1 for its stars were known to the ,greeks of ,alexandria1 but were included in the ,centaur4 ,the latter1 like all those shown in the accompanying illustration1 is of great antiquity1 and probably of ,babylonian origin4 ,the two stars which we call the ,pointers to the ,cross are ,alpha and ,beta of the ,centaur1 and mark his forefeet4 ,another conspicuous pair1 ,delta and ,gamma1 are on his horse's body1 while his man's shoulders are marked by many bright stars1 and the head is formed by a little group4 ,his arm stretches out through bright ,eta to ,kappa1 which is very close to ,beta ,lupi4 ,for the ,centaur and ,lupus form one large and very brilliant group1 and were perhaps connected with the little constellation of ,ara1 the ,altar1 upon which the ,centaur seems to have been imagined as offering the creature which we now know as the ,wolf1 though its older name was simply the ,beast4 ,aratus1 a ,greek poet of about #cjj ,b4,c41 to whom we owe the earliest description extant of the ancient constellations1 says of the ,centaur3 8,his right hand he ever seems to stretch ,before the ,altar's circle4 ,the hand grasps ,another creature1 very firmly clutched1 ,the ,wild ,beast1--so the men of old it named40 ,illustration3 ,the ,old ,constellation ,figures of the ,southern ,hemisphere4 ,on the other side of the ,cross is another splendid constellation1 the ,ship ,argo1 which covers a large space of the sky with many bright stars1 among them ,canopus1 the brightest in the whole heavens except ,sirius4 ,for convenience this large constellation has been divided into four--the ,keel1 the ,poop1 the ,mast1 and the ,sails4 ,sirius is north of ,canopus1 in the constellation of the ,great ,dog--,orion's ,dog1 as it is often called1 for ,orion is a hunter with two dogs2 but the ,little ,dog is in the northern hemisphere1 and ,orion himself has his head in the north and his feet in the south1 his famous belt and sword lying just south of the equator4 ,thus he is visible all over the world1 and only at the poles would his feet or his head never rise above the horizon4 ,beneath his feet is the little ,hare1 as ,aratus says3 8,and ceaselessly beneath ,orion's feet ,the ,hare is ever chased40 ,four stars of the ,hare 71 1 1 71 which form a small square1 were called by the ,arabs the 8,throne of the ,giant0 7i4e4 of ,orion72 or sometimes 8those which quench the thirst of the camel10 in allusion to the river of the ,milky ,way which flows close by4 ,orion is mentioned in the books of ,job and ,isaiah1 and also by ,hesiod and ,homer4 ,above the ,centaur and the ,ship ,argo stretches the long straggling constellation of ,hydra1 the ,water-,snake4 ,its head reaches beyond the equator into the northern hemisphere1 but the beautiful red star ,alphard is in our hemisphere4 ,this ,snake is oddly connected with a ,crow and a ,cup1 which are somehow perched on its back4 7,i have seen a snake pursued by an ,indian crow1 which kept pecking at its tail until the snake found refuge in a stream47 ,crater1 the ,cup1 has no bright stars2 ,corvus1 the ,crow1 is an irregular little square which sailors call ,spica's ,spanker1 a spanker being a sail of this shape1 and two stars of the four point to ,spica1 the bright star of the ,virgin4 ,virgo1 the ,virgin1 is one of the constellations of the ,zodiac1 that zone of stars which marks the apparent pathway of sun1 moon1 and planets in the sky4 ,all the twelve zodiacal constellations can be seen in both hemispheres1 but those south of the equator1 which are least well seen in northern countries1 are of course the best seen in the south4 ,these are the ,scales1 ,scorpion1 ,archer1 ,sea-,goat1 and ,water-carrier1 with a very small part of the ,fishes1 and the part of ,virgo which contains her brightest star1 ,spica1 the ,ear of ,corn held in her hand4 ,the ,romans called her the ,goddess of ,justice1 but these constellations were invented long before ,rome was a great power1 and the ear of corn shows that she was rather a goddess of the fields4 ,they added that the ,scales were her balance wherein she weighed the deeds of men1 but this constellation was of much later origin than the ,virgin3 its place was earlier held by the ,claws of the ,scorpion4#c ,in some old books we find a compromise between the two ideas1 for a pair of tiny scales is hung on the great claws of ,scorpio4 #c ,compare ,aratus3 8,the ,virgin and the ,claws1 the ,scorpion1 ,the ,archer and the ,goat40 ,scorpio is a magnificent constellation as seen in the south4 ,in ,england it merely creeps along the southern horizon in the pale summer skies1 but in southern countries its whole splendid length rises high and shines1 from the bright stars in its head and the ruby ,antares on its back to the sting in its tail1 represented by two stars close together4 ,close behind ,scorpio is ,sagittarius1 the ,archer1 also a brilliant constellation1 with his bow strung ready to shoot the ,scorpion2 he is a centaur1 like the figure near the ,southern ,cross4 ,he is followed by ,capricornus1 a very strange animal1 for it has the head and horns of a goat and the tail of a fish4 ,as a modern writer quaintly says3 8,a startling monster's hybrid form ,your eyes will there assail2 ,that sign so often dubbed the ,goat1 ,yet with a fish's tail40 ,capricorn has very few bright stars4 ,there are two in his goat's head1 of which the brightest1 ,alpha1 is a beautiful naked-eye double1 and there are two in his fish's tail4 ,these three figures--a ,scorpion1 ,centaur-archer1 and ,capricorn--are carved on old ,babylonian boundary-stones belonging to the second millennium ,b4,c4 ,following these is ,aquarius1 the ,water-carrier1 his shoulder marked by the star 1 and his pot by four stars 71 1 1 71 from which fall splashes and streams of faint stars1 aptly representing the water which he is pouring out4 ,he is a familiar figure to those who have lived in some countries of the ,east where water is all carried by hand4 ,illustration3 ,,the ,,archer ,from a ,babylonian ,boundary ,stone now in the ,british ,museum4 ,this is a very watery part of the heavens1 for the zodiacal pair of ,fishes follows the ,water-carrier 7their only bright star in the northern hemisphere71 and there is also a solitary ,fish1 ,piscis ,australis1 swimming in the water poured out2 while a little further east is the great ,sea-,monster1 which belongs to the northern group of ,perseus and ,andromeda and her parents ,cepheus and ,cassiopeia4 ,only the head of ,cetus1 the ,sea-,monster1 is in the northern hemisphere1 but that contains its brightest star4 ,between the dim ,sea-,monster and the bright ,orion flows the winding ,river ,eridanus3 it rises near ,orion's foot1 and now ends very far south in the bright star ,achernar2 but this star was not visible to ,ptolemy when he drew up his star-catalogue in ,alexandria1 and the original ,achernar1 or ,last-of-the-,river1 seems to have been what we now call ,theta ,eridani1 which was much brighter some centuries ago than it is now4 ,al-,sufi1 an ,arab writer of the tenth century ,a4,d41 calls it a star of first magnitude4 ,to complete our survey of the constellations south of the equator we must add the tip of the ,eagle's wing1 the legs of the ,unicorn1 and part of ,ophiuchus with the ,serpent he is strangling as he treads the ,scorpion under foot 7a gallant hero1 to contend with both these enemies at once74 ,it is worth noting that just as the three stars of ,orion's belt mark the celestial equator in one part of the sky1 so the three bright stars of the ,eagle mark it in the opposite part 7,altair1 with and on either side72 but they are just north of it1 and ,orion's belt is just south4 ,as it is often interesting to know where the ecliptic lies1 we may point out that the following southern stars lie near it3 ,spica1 ,librae1 ,antares1 and ,capricorni 7and in the north the ,pleiades1 ,aldebaran1 ,regulus74 ,it is also convenient to remember the positions of a few constellations as a guide to right ascension4 ,thus1 ,achernar is in the ,ist hour1 ,canopus and ,sirius are in the ,v,ith1 the ,cross and ,corvus in the ,x,i,ith1 and the ,bow of ,sagittarius is in the ,x,v,i,i,ith4#d #d ,right ascension in the skies corresponds with longitude on earth1 but is more often reckoned in time than in degrees4 ,for instance1 ,r4,a4 #a hour #ce minutes1 the right ascension of ,achernar1 means that this star will be on the meridian #a hour #ce minutes later than the 8first point of ,aries0--that is1 the point at which the equator cuts the ecliptic at the spring equinox1 the fundamental point corresponding with ,greenwich in earthly longitude4 ,there are more bright stars in the southern hemisphere than in the north1 for a count of all those above fourth magnitude shows that there are #bbh south of the equator against only #afd north4 ,but whereas the stars in the north are fairly evenly distributed1 there is a more strongly marked tendency in the south to congregate on the ,milky ,way1 so that1 while the tract through ,argo and the ,cross to ,scorpio and ,sagittarius is extraordinarily rich1 the part between ,orion and ,fomalhaut is comparatively dark and bare1 and the regions round the south pole and north of ,argo are also very barren of bright stars4 ,some regions1 however1 which look dull to the eye abound in marvels for the telescope and camera4 ,the brilliance and the complex structure of the ,milky ,way is undoubtedly what most strikes the northerner travelling south4 ,in ,england we have a glimpse of it in ,cygnus and ,aquila1 where this rich and bright part begins2 but there is nothing to equal the brightness or the mingling of dark and light which we see in ,argo and near the ,cross1 in ,scorpio and in ,sagittarius4 ,when this part is about to rise1 there is often a glow on the horizon as if it were dawn4 ,,iii ,,the ,,ten ,,brightest ,,stars ,,of ,,the ,,southern ,,hemisphere ,the brighter of the two ,pointers to the ,cross1 ,alpha ,centauri1 ranks very high among first-magnitude stars1 though it is excelled in brightness by ,sirius and ,canopus2 but its greatest claim to our interest is that among all the host of stars it is our nearest neighbour4 ,yet1 should we decide to pay a visit and travel with the speed of light 7#aa million miles a minute71 it would be four years and three months before we could reach our destination--so great are the spaces which separate our sun with his family of planets from the nearest of his brother suns4 ,alpha ,centauri is also interesting as a double star4 ,the two components are nearly equal in brightness1 and are seen as a brilliant yellow pair in quite a small telescope4 ,it was one of the first doubles known1 being discovered as such in #afhi2 and ,herschel calls it a 8superb double star1 beyond all comparison the most striking object of the kind in the heavens40 ,the two stars he describes as 8both of a high ruddy or orange colour1 though that of the smaller is of a somewhat more sombre and brownish cast40 ,all stars are suns1 but they vary so much in brightness and size and quality of light that it is as difficult to match two stars in the sky as two trees in a wood4 ,yet one of this pair is an almost exact counterpart of our sun4 ,the pair is approaching us1 and at the same time revolving one about the other in a period of about eighty years4 ,the other ,pointer1 ,beta ,centauri1 is a star very different from our sun4 ,it belongs to a type called 8,orion stars0 because so many are found in that constellation4 ,instead of shining with a yellow light1 they are blue or bluish-white1 and their glowing atmospheres contain quantities of helium1 the gas which was only recently discovered on earth though it had been known for many years in the sun4 ,oxygen and nitrogen and some yet unknown elements are also present4 ,alpha ,crucis1 the brightest star of the ,cross1 is also a blue ,orion star1 and the telescope shows it to be triple4 ,there are two bright twin stars1 and a fainter one which would be just visible to the naked eye if alone1 but being overpowered by the brilliance of the bright pair can only be seen in a large telescope4 ,quite a small telescope will separate the twins4 ,achernar1 the ,last-of-the-,river1 is also an ,orion star1 #ge light-years distant from us--i4e4 light takes #ge years to come from it to us4 ,the sun if removed to a third of this distance would be barely visible to the naked eye4 ,rigel1 ,orion's foot1 is the brightest star of this class4 ,its intrinsic brilliancy and its size must be enormous1 for its distance is certainly more than #cfj light-years1 and may be greatly more4 ,and the distance is increasing at the rate of #ci miles a second4 ,rigel is also a double star1 but its companion is very faint4 ,in an #h-;inch telescope the bright star looks white or pale lemon-yellow1 contrasting beautifully with the little companion which is blue4 ,spica1 the ,ear of ,corn in the hand of the ,virgin1 is immeasurably distant from us1 and its companion is invisible even in the most powerful telescopes4 ,it was discovered by means of the spectroscope1 for1 when the light of the star is drawn out into a long rainbow-coloured ribbon crossed by dark lines1 it is found that there are two ribbons1 one bright1 the other very faint1 and that the lines of these two spectra draw apart and then come together again once in every four days1 showing that there are two stars close together and revolving round one another in this short time4 ,the joint mass of the pair is two and a half times that of the sun4 ,spica is one of the first stars whose invisible companion was discovered in this way1 and it is also connected with another discovery1 made nearly twenty centuries earlier by ,hipparchus in the island of ,rhodes4 ,he was patiently plotting the positions of all the visible stars1 when he found a slight discrepancy between the places given to ,spica by himself and another ,greek astronomer1 who had observed about a hundred and fifty years earlier4 ,examining into this led him to discover that all stars change their apparent positions very slowly1 completing a cycle of change in nearly #bf1jjj years1 so that #bdj centuries more must elapse before any astronomer sees ,spica in exactly the same place as where ,hipparchus saw her4 ,it remained for modern astronomers to discover that the apparent change is due to a slow nodding motion of the ,earth's axis4 ,brightest of all stars in the whole sky is ,sirius1 the ,dog-,star4 ,it was worshipped by the ancient ,egyptians1 and the day on which it rose just before the sun was counted as the first day of their year4 ,the ,arabs1 when they learned the astronomy of more ancient nations1 were forbidden to adopt their star-worship1 hence the saying in the ,koran1 often quoted by ,arab writers3 8,the ,highest saith1 ,he is lord of ,sirius40 ,sirius is moving rapidly through space1 not uniformly but with an oscillating movement1 and ,bessel in #ahdd 8founded the astronomy of the invisible0 by showing that these irregularities might be caused by a dark disturbing companion4 ,eight years later1 ,mr4 ,alvan ,clark1 wishing to test a large lens just made by his firm1 turned it on ,sirius1 and lo6 there was the satellite in the position required to explain the vagaries of ,sirius4 ,it is not therefore wholly dark1 but it shines with so feeble a light that1 if it were brought as near to us as our own sun1 it would appear only one-hundredth as bright as he is1 even though it is a somewhat more massive body4 ,sirius itself is only about two and a half times as massive as our sun1 but immensely more brilliant4 ,it is the typical star of the 8,sirian0 class1 to which belong many of the brightest stars in the heavens1 white stars in whose spectra broad hydrogen lines form the most striking feature1 indicating a very extensive atmosphere of glowing hydrogen4 ,bright ,sirius and his dim companion revolve round their common centre of gravity in fifty years4 ,fomalhaut1 the mouth of the ,fish1 belongs to the ,sirian type of stars1 and is also very brilliant1 giving out fourteen and a half times as much light as our sun4 ,its distance is #be light-years4 ,canopus1 the rudder of the ,ship ,argo1 must be a giant sun1 for its distance is altogether beyond reach of measurement and it is steadily receding from us1 yet it shines as the brightest star in the sky except ,sirius4 ,in ,southern ,india it is called ,agastya1 after a ,brahmin rishi who led an early ,aryan colony to the south1 and before whom the ,vindhya ,mountains prostrated themselves as he passed4 ,greek astronomers noticed that this star rose only just above the horizon of ,rhodes1 but #g degrees above it at ,alexandria1 from which ,poseidonius calculated that the circumference of the whole earth1 i4e4 #cfj1 must be #bdj1jjj stadia4 ,this is equal to nearly #bc1ejj miles1 a value surprisingly near the correct figure1 considering how difficult it must have been to measure the distance over the sea between ,rhodes and ,alexandria4 ,antares1 the brightest star in the ,scorpion1 was so named by the ,greeks because it rivals the red planet ,mars 7,greek ,ares7 in colour4 ,it is red because a dense atmosphere shuts out most of its blue rays4 ,like most red stars it is very distant1 and its light takes #aee years to reach us4 ,nevertheless it shines #bjjj times as brightly as our sun would do at the same distance1 hence it must be of an enormous size4 ,this immense red star is accompanied by a little green satellite1 and there is also a very close companion which can never be seen1 but is known to exist through the shifting of lines in the spectrum1 like that of ,spica4 ,what an amazing variety among these ten stars6 ,though the eye can only decide that all are much brighter than the average1 and that they differ somewhat in colour among themselves1 science tells us that they vary enormously in many ways4 ,half belong to the class of blue ,orion stars1 others to the white ,sirian1 yellow solar1 red ,antarian classes2 more than half are known to be double or multiple1 and among these we find twins1 while others have faint companions differing from themselves in colour4 ,in one case the pair is widely separated1 and revolves in a period of half a century1 while another pair is so close that the circuit is performed in four days4 ,again1 while one star is the same size as the sun1 others are much greater1 and their distances from us vary all the way from four light-years to spaces we are powerless to plumb4 ,,iv ,,stars ,,of ,,different ,,ages ,what is the meaning of these different types of stars--the blue1 the yellow1 and the red8 and can a star change its colour and type8 ,yes1 we believe that all the blue stars1 if they follow the normal course1 will in countless ages become red1 and though the life of the whole human race may perhaps not be long enough to witness a single instance1 we feel confident that this process is going on4 ,one walk through a forest is enough to teach us that a tree grows from seed to sapling1 from maturity to decay1 because we see trees around us in all these stages4 ,so with the stars4 ,here the process of development is far more difficult to understand1 and we are still ignorant concerning the birth and death of stars2 but it is clear that we see a series of stages which pass gradually into one another1 and that the cause of a star's growing old is a gradual loss of heat by radiation4 ,the blue ,orion stars are the brightest and hottest of all those about which we have spoken1 and are generally thought to have reached the climax of a star's career4 ,they are great globes of thin gas1 much less dense than water1 but glowing hot through and through4 ,the outer layers naturally part with their heat first1 and in cooling they absorb more and more light from the radiant centre4 ,as the blue rays are always first and most powerfully affected1 the blue tint is soon lost1 and the colour slowly changes through white1 yellow1 and orange to deep-red4 ,at the same time changes take place which cause different gases to become most conspicuous in the star's spectrum at different stages4 ,but what are the early stages which precede the brilliance of an ,orion star8 ,arguments have been brought forward to show that young stars also are comparatively cool1 but even less dense than ,orion stars1 that as they grow denser and smaller through gravity1 which causes all the particles of a star to condense towards its centre1 they must at first grow gradually hotter and brighter until a certain point is reached1 after which they will grow cooler and fainter again until they become quite cold and dark2 and so there is a double progression1 viz4 from red towards blue1 and back again to red1 some stars changing in one direction and some in the other4 ,on the other hand1 the stage which immediately precedes the ,orion type somewhat resembles a peculiar class of nebulae1 so the upward progression of the ,orion stars may have been from nebulae through this stage4 ,let us see what these stages are4 ,at one end of the series we find stars like ,gamma in the ,sails of the ,ship ,argo4 ,when its light is spread out by prisms into a coloured band it is a wonderful sight1 for not only are there dark lines and dark flutings1 but wide bright bands mingle with these and stand out against the fainter background4 ,we are fortunate to possess ,velorum in the southern hemisphere1 for it is the only bright star of its class4 ,the type is known as ,,wolf-,,rayet ,,stars1 from the name of their discoverer4 ,only a few are known1 and because of their faintness not very much has been discovered about them1 but it is remarkable that all of them lie near the middle line of the ,milky ,way4 ,the bright lines in their spectra and some other features of ,wolf-,rayet stars point 7as we have said7 to a connection with gaseous nebulae1 and it is possible that they developed from nebulae not very long ago--as time is reckoned in astronomy4 ,though this past is doubtful1 the future of these stars is clearly indicated3 they are destined to become ,orion stars1 for in stars like ,canis majoris we see an intermediate stage between the two types4 ,,orion ,,stars sometimes have bright lines in their spectra also1 especially the very blue ones found near nebulae1 but the most striking and characteristic feature is the series of dark helium lines1 from which they are often called 8helium stars40 ,the three in ,orion's belt are typical of this class2 several first-magnitude stars belong to it1 as we have seen1 and it contains others which are very bright1 such as and ,crucis1 ,scorpii1 ,lupi1 ,pavonis1 ,gruis1 ,sagittarii4 ,spica is a distinctly blue ,orion star2 ,rigel and ,gruis have already lost the blue tint and are approaching the next stage4 ,for the ,orion class passes by gradual transition into the ,,sirian ,,stars1 which may be called 8hydrogen stars10 from the wide hazy lines of hydrogen which are the most conspicuous feature in their spectrum4 ,they are also very hot and bright1 though less so than the ,orion stars4 ,besides ,sirius1 a large number of bright southern stars belong to this class1 among which we may mention ,fomalhaut1 ,centauri1 ,carinae1 ,velorum1 and ,pavonis4 ,among stars visible to the naked eye this is by far the most numerous class1 partly1 no doubt1 because they are intrinsically bright and therefore visible at distances where redder stars could not be seen4 ,this cannot however be the whole explanation1 or the ,orion stars would be still more numerous instead of being comparatively rare4 ,the blue end of the spectrum begins to be darkened as a star reaches the stage of sun-like or ,,solar ,,stars1 and although the hydrogen lines grow narrower and less intense1 an immense number of fine lines cross the bright band and absorb much of the light4 ,centauri1 as we have seen1 is a replica of the sun1 and another star which almost exactly resembles it1 in spectrum if not in mass1 is ,hydri4 ,gruis and one star of the naked-eye double in ,grus1 ,gruis1 are also solar stars4 ,this class may be subdivided into three3 the ,sirian-solar1 which is typified by ,canopus1 and also by ,crucis and ,hydri2 the solar1 closely resembling the sun2 and the red-solar1 which tend towards the red stars4 ,the temperatures apparently are lower and lower in these three divisions in the order given1 and all solar stars are cooler than those of the preceding classes4 ,among these red-solar stars is the beautiful ,carinae1 the foot of the ,false ,cross1#e which is a rich reddish orange even to the naked eye1 and more brilliantly coloured in a binocular4 ,others are ,toucani1 ,trianguli australi1 ,crucis 7the little fifth star of the ,southern ,cross71 the two brightest stars of ,indus 7 and 71 almost all the bright stars of the ,phoenix 71 1 1 71 and ,scorpii which is beautifully coloured4 ,this class is also extremely numerous among naked-eye stars1 although they cannot be so bright intrinsically as the whiter solar stars3 the significance of the fact is not easy to understand4 #e ,the stars and ,carinae1 and ,velorum1 form a cross much like the ,southern ,cross1 but less bright1 and this is called the ,false ,cross4 ,the deep-red stage is reached in suns like ,antares1 whose spectrum shows not only lines like those in the sun but also a series of broad bands or flutings which absorb much of its light1 and in photographs a great part of the violet end is wholly cut off4 ,were it not such an enormous size1 this would be a very dim star4 ,,antarian ,,stars are almost all very remote4 ,they are often very faint1 and many of them are unstable in their light1 as if fluctuating towards extinction4 and ,gruis and ,hydri are among them1 and ,mira1 the wonderful variable star4 ,compare the ruddy in the ,cross with pale to see the contrast between stars of this class and the ,orion-type4 ,because of the want of blue rays in the former it makes so little impression on a photographic plate compared with 1 1 and 1 which are all ,orion stars1 that one can scarcely recognise the form of the ,cross in a photograph4 ,the brightest of these red stars are in the northern hemisphere1 viz4 ,betelgueux in the shoulder of ,orion1 and ,aldebaran1 the eye of the ,bull3 both are slightly brighter than ,antares4 ,nearly all the stars we know have a place in this series1 though there are individual peculiarities1 but there is one class which seems to lie outside it4 ,stars of this class are red and have spectra crossed by dark bands1 but they are unlike the ,antarian bands and resemble instead those seen in the spectra of comets and of candle-flames4 ,they are due to carbon compounds1 so these stars may be called ,,carbon ,,stars4 ,most of them are extremely remote1 and all are so faint that among the very brightest is ,u ,hydrae1 just visible to the naked eye a little east of ,alphard4 ,they are probably aged stars1 but no links between them and the other types have yet been discovered to enable us to place them in the series4 ,strange and interesting discoveries have been made by grouping large numbers of stars into their classes and comparing the average motions1 distances1 c41 of the groups4 ,it is found that the redder stars are on an average moving more rapidly and in a more random fashion than blue and white stars4 ,thus1 ,wolf-,rayet and ,orion stars have a low average speed1 and both are very much more numerous in and near the ,milky ,way than elsewhere2 ,sirian stars are travelling a good deal faster1 show a marked tendency to congregate in two streams1 and move chiefly parallel with the plane of the ,milky ,way2 solar stars1 including our own sun1 move more rapidly still and show less preference for the ,galaxy and the two streams3 ,antarians have the most rapid motions of all1 but these appear to be haphazard1 and the stars are scattered all over the sky in every direction4 ,these facts are very unexpected and very difficult to explain4 ,it looks as if the ,milky ,way were the birthplace of the stars1 and that as they develop they gradually scatter through space2 but how are we to explain the fact that speed and direction of movement differ for different types8 ,there seems to be no reason why a cooler star should move more quickly than a hotter one1 and none of the theories yet advanced can be considered final4 ,v ,,some ,,near ,,neighbours ,if it is remarked that ,sirius is fifty millions of millions of miles away from us1 it is not at once obvious that he is one of our very near neighbours2 but this is equal to #h light-years1 not twice the distance of ,centauri1 our next-door neighbour among the stars4 ,some faint stars in the south must also be counted as very close to us3 such are a little star in ,cetus1 ,ceti1 only #aj light-years away2 ,indi1 #aa2 and two in the ,river ,eridanus1 and ,eridani1 #aj and #ah respectively4 ,but the most interesting among these near neighbours of the south is a little yellow star in ,pictor1 too faint to be seen without a good binocular or a telescope1 and bearing the very modern name of ,,cz #e4bdc4 ,this stands for ,cordoba ,zones #e4bdc hours1 and means that it was catalogued at ,cordoba ,observatory in ,south ,america and its position fixed in the fifth hour of ,right ,ascension4 ,after this it was observed by ,mr4 ,innes at the ,cape1 and he was startled to find 7like ,hipparchus comparing his work with that of ,timocharis7 that its position no longer agreed with that found at ,cordoba4 8,can this be motion80 he asked1 and found that the star had indeed a larger visible motion across the sky than any other1 not even excepting the famous 8runaway star0 in ,ursa ,major4 ,apparent motion1 however1 depends upon distance as well as real speed1 and when the distance of ,,cz #e4bdc had been calculated it was found that its real speed1 amazing as it is1 yet falls slightly short of that of the northern star4 ,the rates are #afc and #agd miles per second4 ,a few other stars are known to move at speeds approaching #ajj miles a second1 and one was announced in ,december #aiac to have a velocity of #bjj miles a second1 but runaway stars are rare4 ,they do not seem to show any preference for special parts of the sky or special stellar types1 and it is impossible to say what causes them to rush with such headlong haste through space1 or what is their goal4 ,the average rate for a star is about #ac miles a second1 but1 as we have seen1 it differs with different types1 the average speed increasing progressively from the blue to the red classes4 ,another remarkable fact lately discovered is that the different types of stars are not indiscriminately scattered through space4 ,our own sun seems to be surrounded1 to a distance of about #ajj light-years1 by suns more or less like himself1 while the greater number of the red ,antarian stars lie at a much greater distance from us4 ,most distant of all1 considered as a class1 are the bluest of the ,orion stars2 for though the distances of individuals vary greatly1 the average distance of these stars from us is more than #ejj light-years4 ,yet they are often very bright1 so this is another proof of their great intrinsic brilliancy4 ,,vi ,,double ,,and ,,multiple ,,stars ,among the brighter stars at least one in four is double1 and ,i shall only mention a few which for different reasons are of special interest4 ,the brightest double in the sky has already been mentioned1 ,centauri1 and we have also described another southern pair scarcely less brilliant1 ,crucis1 ,sirius with his very dim companion1 ,rigel and ,antares with theirs of contrasting colours4 ,other fine southern doubles are3 ,piscis australis1 a white star with reddish companion1 visible in a #c-;inch telescope4 ,corvi1 an unequal distant pair1 pale yellow and bluish1 easily separated in a #d-;inch telescope4 ,scorpii 7near ,antares71 white and blue4 #cb ,eridani1 yellow and blue-green--8magnifici1 superbi10 according to ,secchi4 ,capricorni 7close to the splendid naked-eye double ,capricorni71 orange-yellow and blue4 ,crucis1 orange-yellow1 companion fifth magnitude1 rather distant4 ,leporis1 companion crimson4 ,there is also a third faint star1 forming a triple group4 ,capricorni1 like ,antares1 besides its visible companion1 has a close invisible one1 only known by the shifting of lines in the spectrum1 and this is not an uncommon case4 ,crucis consists similarly of two bright stars and a spectroscopic companion1 and so also ,eridani4 ,velorum and ,pavonis have spectroscopic companions only1 one revolving in a period of #aaf days1 the other of only #aa days1 and the period of ,scorpii is counted in hours6--#cd hours #db minutes4 ,the brief periods of these spectroscopic binaries#f are in striking contrast with those of many visual binaries1 such as ,sagittarii with a period of #ai years and ,centauri with #aej years2 and this is what one would expect1 since the stars must be comparatively far apart and their orbits ample for them to be visible separately4 ,sometimes the stars of a pair or of a group are known to be moving together through space1 though no movement of revolution round a common centre has yet been detected1 probably because it is very slow4 #f ,a 8binary0 is a system of two stars which are known to be comparatively close together and influencing one another's movements4 ,a 8double star0 may be a binary1 or the two stars may really be very far apart and have no connection1 merely happening to lie one nearly behind the other4 ,it is an interesting fact that most of the spectroscopic binaries1 which are such close and rapid pairs1 are found among the blue and white stars1 the numbers steadily decreasing as we pass through the yellow to the red stars4 ,a significant fact about visual binaries is that companions which differ much in colour invariably differ much in brightness also4 ,this is probably to be explained by supposing that one was from the beginning much larger than the other1 and that there is consequently a difference in the rapidity with which each runs through its life-changes4 ,where the two are alike in colour and spectrum1 like the two solar stars of ,centauri and the two ,orion stars of ,crucis1 it is found that they are also nearly equal in mass1 so they keep the same pace and grow old together4 ,among multiple stars there are some very remarkable instances in ,scorpio4 ,scorpii is a pair of bright stars 7easily separated with a #c-;inch telescope7 with a third fainter companion1 and besides these1 one of the bright components is a spectroscopic pair1 and the whole company is travelling together through space4 ,the joint mass of the spectroscopic pair is twenty-one times as great as that of our sun1 and they revolve about one another in seven days2 but a very strange feature is that some lines in their joint spectrum1 due to calcium gas1 behave differently from the rest1 and it is thought that these two revolving stars may be enveloped in a calcium cloud which travels with them4 ,scorpii is a telescopic double which has been watched throughout a complete revolution of ninety-six years4 ,it was discovered by ,sir ,william ,herschel in #aghb4 ,here also there is a third star1 much fainter and more distant than the brighter companion1 and all are travelling together through space4 ,scorpii is one of the 8double-doubles10 of which a good many are known1 where a star that looks single to the naked eye is seen as a pair with a telescope1 and each of these becomes a pair with higher powers4 ,it has been described as 8perhaps the most beautiful quadruple in the heavens40 ,both pairs journey together through the skies4 ,orionis1 the fourth-magnitude star just below ,orion's belt1 separates very easily into two unequal components4 ,herschel found each of these to be triple1 and called it a 8double-treble40 ,later it was found to be 8double-quadruple10 with more stars between the two groups4 ,in the same way the beautiful naked-eye double star ,capricorni is seen in good telescopes to consist of two groups of stars1 one 77 triple1 the other 77 quadruple4 ,if a group like this forms a connected system1 the motions of the several stars must be highly complicated4 ,,vii ,,the ,,astonishing ,,star1 ,,eta ,,arg,s ,midway between the ,southern ,cross and the ,false ,cross there is a nebula visible to the naked eye1 and in it once shone a bright star4 ,when ,halley was observing in the southern hemisphere towards the end of the seventeenth century1 he catalogued it as of fourth magnitude1 but ,lacaille and later astronomers marked it as second4 ,sir ,john ,herschel first saw it in #ahcd1 when he was at the ,cape1 and he says that it remained steady for three years1 from #ahcd to #ahcg4 ,on the #afth of ,december #ahcg he began his observations as usual by noting the brightest stars in the heavens and arranging them in order on a list1 when to his astonishment he saw 8a new candidate for distinction among the very brightest stars of first magnitude0 in a part of the sky where he was quite sure no such brilliant object had been seen before4 ,he consulted a map and satisfied himself that it was his 8old friend ,eta ,args10 but nearly three times as bright as usual4 ,he made careful comparisons with other bright stars then visible1 and says that 8,fomalhaut and ,alpha ,gruis were at the time not quite so high1 and ,alpha ,crucis much lower1 but all were fine and clear1 and ,eta ,args would not bear to be lowered to their standard40 ,it was a little brighter than ,rigel1 and the only stars which outshone it were ,sirius and ,canopus4 ,still it grew brighter1 for twelve days later it greatly surpassed ,rigel and could only be compared with ,centauri4 ,after this the light began to fade1 and by ,april #ahch it was not much brighter than ,aldebaran4 ,herschel now returned to ,england1 and therefore he did not see the still more startling changes of this wonderful star1 but he has recorded what he heard from others4 ,in ,march #ahdc it became much brighter than ,rigel or ,centauri1 but its light wavered1 and he says3 8,we have here an epoch of great interest1 a temporary minimum1 with a kind of trepidation or fluttering of light1 followed1 however1 by another step in advance even yet more extraordinary40 ,this was in the following month1 ,april #ahdc1 when ,eta became almost equal to ,sirius1 the brightest of all stars4 ,it was the highest point reached by this extraordinary star1 and two years later ,maclear at the ,cape wrote to the ,astronomer-,royal in ,england3 8,when you see ,sir ,john ,herschel again1 tell him that ,eta ,args has been for some time rather larger than ,canopus1 and seems again on the decline40 ,sir ,john's concluding remarks seem to indicate something of pained surprise that a star could behave in so erratic and unaccountable a fashion3 8,a strange field of speculation is opened by this phenomenon4 ,here we have a star fitfully variable to an astonishing extent1 and whose fluctuations extend over centuries4444 ,what origin are we to ascribe to these sudden flashes and relapses8 ,what conclusions are we to draw as to the comfort or habitability of a system depending for its supply of light and heat on so uncertain a source80 ,eta ,args continued to fade1 and for many years it has not been visible to the naked eye4 ,when the present writer looked for it in ,april #aijh it was beyond the power of the binocular1 although seventh-magnitude stars in the neighbourhood were clearly distinguished and identified4 ,in a telescope it in no way stands out from the crowd of small stars scattered over the nebula whose light it once almost blotted out by its brilliance4 ,reports now and then arise that ,eta is brightening again1 but it always turns out that some neighbour in the throng1 a little brighter than the faded star1 has been mistaken for it4 ,a few other cases are known in which a bright star has appeared where none had been seen before4 ,it is said that it was the appearance of such a 8new star0 in ,scorpio in the year #acf ,b4,c4 which led ,hipparchus of ,rhodes to draw up his famous star-catalogue4 ,in ,a4,d4 #aegb 8,tycho's star0 blazed out in ,cassiopeia1 and in #afjd 8,kepler's star0 in ,ophiuchus astonished everyone4 ,the old chronicle says3 8,it was exactly like one of the stars1 except that in the vividness of its lustre and the quickness of its sparkling it exceeded anything ,kepler had ever seen before4 ,it was every moment changing into some of the colours of the rainbow1 as yellow1 orange1 purple1 and red1 though it was generally white when it was at some distance from the vapours of the horizon40 ,this 8new star0 must have been even brighter than ,eta ,args1#g for it outshone ,jupiter1 and was only surpassed by ,venus4 ,it remained visible for about a year and then vanished4 #g ,now often called ,eta ,carinae1 since ,argo has been subdivided 7see p4 #g74 ,since the skies have been more carefully watched by astronomers all over the world1 and especially since they have been frequently photographed1 quite a considerable number of new stars have been recorded1 and about half a dozen have become visible to the naked eye4 ,in the twenty-seven years between #ahhe and #aiab1 twenty were recorded1 and half of these were discovered by ,mrs4 ,fleming of ,harvard ,observatory from the examination of photographs4 ,astronomers are still asking1 like ,herschel1 what is the origin of these mysterious objects8 ,are they literally new stars1 or is it the last flare-up of a dying system1 or are we witnessing some catastrophe which only overtakes a few suns among the universe of stars8 ,a collision between two dark stars1 or between a star and a nebula1 is a supposition which naturally suggests itself1 and some probability is lent to this supposition by the fact that nearly every new star has appeared in or near the ,milky ,way1 where stars throng most thickly2 but there are difficulties in the way of accepting this hypothesis4 ,there is a strong likeness between all that have been examined spectroscopically1 and in the declining stage they become so distinctly nebular in type that we seem justified in saying that new stars change into small gaseous nebulae4 ,does this mean that they are dying1 or is it the first stage in the life-history of a star1 immediately preceding the not altogether dissimilar ,wolf-,rayet stage8 ,we do not know enough yet about nebulae to answer this question4 ,,viii ,,mira1 ,,the ,,wonderful ,,star ,the head of ,cetus1 the ,sea-,monster1 is formed of three stars in a crooked line 71 1 72 and a little beyond them1 as far from as that is from 1 you may sometimes see another star1 marked on the map by the name 8,mira10 which means 8,wonderful40 ,watch it carefully1 and if it is on the upward grade you will see it slowly brighten until it equals 1 then 1 and if you are lucky it may even approach in brightness2 and meanwhile it will pass from red to a clear orange-yellow2 then it will wane once more and gradually be lost to view1 though you can follow it much longer in even a small opera-glass1 and you will notice that as it grows fainter the colour becomes deeper and deeper crimson4 ,unlike ,args with its one brilliant phase in two centuries1 ,mira waxes and wanes once in every eleven months1 although there is a capricious uncertainty in both the period and the brightness which makes her a most fascinating object to observe4 ,sometimes the maximum brightness is several days earlier1 sometimes later1 than the average2 sometimes she only equals 1 she has been seen to excel 2 and no one can foretell exactly what and when her maximum will be4 ,quite a number of other stars have been discovered which behave like ,mira1 and anyone who wishes to contribute something to astronomical research without having to buy large and expensive instruments1 or to study difficult problems1 cannot do better than observe some of these stars1 carefully comparing them night after night with stars in the neighbourhood4 ,here is a list of a few southern 8variable stars of long period10 as they are called1 all of which are easily visible at maximum brightness with a binocular1 and some even without4 ,a map should be made of the surrounding stars1 and a list drawn up of those which are of the different magnitudes through which the variable passes4 ,every fine night the star should be compared with these1 and recorded in a note-book as brighter than one1 fainter than others1 perhaps equal to another1 and so on1 several comparisons being made to check each other4 ,when the variable passes out of the range of the binocular1 this should be noted4 ,the ,british ,astronomical ,association1 which has a branch in ,australia1 has a ,variable-star ,section1 and anyone who becomes a member will receive ready help and advice1 and may have the pleasure of feeling that he is doing useful work in astronomy4 ,most long-period variables are red stars of the ,antarian or of the carbon star classes with banded spectra1 but they differ from ordinary red stars by occasionally showing bright lines1 which indicate an uprush of intensely hot hydrogen gas in their atmospheres4 ,these bright lines always appear at times of maximum1 and prove that the star periodically undergoes some physical change3 but what is the nature and the cause of this change8 ,it can scarcely be due to the near approach of a satellite1 because of the irregularity in the time of maximum4 ,there is a certain resemblance between the way in which the light waxes and wanes and the waxing and waning in the number of sunspots on the sun1 and spectra of these ,mira stars also somewhat resemble sunspot spectra3 can it be that our sun is an incipient variable star with a period of about eleven years8 ,it is true that sunspots seem to be cooler rather than hotter regions on the sun1 but a time of maximum spots is also a time of maximum activity2 slightly more heat is actually radiating1 the corona is brighter and larger1 and the bright scarlet flames of hydrogen and calcium which we call prominences are larger and more abundant4 ,possibly it is a tremendous display of these on ,mira which makes the hydrogen lines bright at maximum4 ,,some ,,southern ,,variable ,,stars ,,of ,,long ,,period ---------------------------------------- ----------------------- ,name4 ,maximum ,minimum ,period4 ,remarks4 ,magnitude4,magnitude4 ---------------------------------------- ----------------------- ,days4 ,mira #a4g #i4f #cca ,discovered in #aeif4 ,large irregular- ities in period and max4 brightness4 ,r ,sculptoris #f4b #h4h #cgf ,a red 8carbon star40 ,r ,leporis #f4a #i4g #dcf ,crimson4 ,a 8carbon star40 ,observed from #aheb to #ahhc1 but very few observations published since1 so new work would be valuable4 ,t ,centauri #f4e #h4j #ij ,period unusually short for this class of variables4 ,r ,centauri #e4c #ac4j #efh ,an ,antarian star4 ,double max4 and min4 ,the secondary min4 about mag4 #h4 ,r ,scuti #d4h #g4h 8 ,bright and faint minima1 usually alternative4 ,period perhaps irregular4 ,s ,sculptoris #e4h #aa4h8 #cff ,r ,horologii #e4i #ab4j #dje ,l ,puppis #c4d #f4b #adj or longer ,r ,carinae #d4e #aj4j #cji ,antarian stars4 ,spectra very similar ,s ,carinae #e4h #i4j #adh to that of ,mira4 ,r ,hydrae #d4j #i4h #dbe ,s ,virginis #e4f #ab4c #cgi ,r ,aquarii #f4b #aa4j #chg ---------------------------------------- ----------------------- ,against this suggestion we must set the fact that no stars have been found to link together the slow and slight change represented by the sunspot period with the rapid and violent change suffered by ,mira variables4 ,their periods1 though never less than three months1 are never more than two years1 and the light radiated by ,mira at maximum sometimes amounts to five thousand times as much as at a faint minimum4 ,nevertheless1 the fact that these perplexing stars are a link in an unbroken chain of which our sun also forms part suggests that research on the sun1 our nearest star1 will some day help us to understand more about ,mira and stars like ,mira4 ,,ix ,,eclipsing ,,stars ,there is another type of variables quite distinct from the ,mira stars4 ,these run through smaller light-changes in much shorter periods1 also they change abruptly with clockwork regularity1 and the spectrum shows no bright lines at maximum1 indicative of physical change4 ,the first known was ,algol1 the ,ghoul or ,demon ,star in ,perseus1 and the brightest southern star of the ,algol type is ,librae4 ,it shines steadily for a little more than two days as a fifth-magnitude star1 then in a few hours drops suddenly to below sixth magnitude1 becoming invisible to the naked eye1 and as quickly recovers its usual brightness4 ,the entire change takes place regularly in less than two and a half days4 ,a few bright ,algol stars in the south are3 ,,southern ,,algol ,,variables ---------------------------------------- ------- ,name4 ,maximum ,minimum ,period4 ,magnitude4,magnitude4 ---------------------------------------- ------- ,days4 ,hours4 ,,rs ,sagittarii #e4i #f4c #b #i ,r ,canis majoris #e4h #f4d #a #b ,librae #d4h #f4b #b #g ,r ,arae #f4h #g4i #d #i ---------------------------------------- ------- ,altogether nearly a hundred ,algol stars are now known1 and seventy-four of these lie in or near the ,milky ,way4 ,unlike the mysterious ,mira stars1 the variation of ,algol stars has been explained4 ,the sudden drop in the light is a partial eclipse1 caused by a dark or partly dark companion which for a time hides the bright star from us4 ,when a source of light is coming towards us1 the lines in its spectrum are shifted towards the violet1 when going away they are shifted towards the red1 exactly as the whistle of an engine becomes more shrill when approaching us1 and falls to a lower pitch when going away4 ,in this way it has been discovered that an ,algol star is revolving round an invisible companion1 for it alternately approaches and recedes1 and these movements correspond with its light-changes4 ,it is1 in fact1 a spectroscopic binary which happens to have an orbit whose plane lies just in our line of sight1 so that at every revolution one star passes behind the other4 ,the speed of the star in its orbit can be accurately determined 7by the amount of shift in the spectrum lines7 in miles per second1 even when we do not know its distance from us2 hence the size of its orbit can be calculated1 since we know the period in which it is completed2 and1 further1 the size of the orbit gives us the mass of the stars1 for their movements depend upon the attraction they exercise over one another1 and this is proportional to their mass2 and so we are able to picture the system1 although the eclipsing star is never seen and the distance from us may never be known4 ,here is indeed a triumph of modern astronomy4 ,very curious are the systems thus discovered4 ,algol stars are extraordinarily light for their size1 their density being always less1 and sometimes immensely less1 than that of water1 and the companions are usually extraordinarily close together4 ,in some pairs they seem to be actually touching4 ,nearly all are ,sirian stars2 a few are of ,orion and solar types4 ,sometimes the companion star gives light also1 instead of being dark1 and then we have a different type of variation4 ,there are two eclipses in one revolution1 each star passing alternately behind the other1 but neither is a very dark eclipse1 only a lessening of light4 ,lyrae was the first star of this kind to be discovered2 its southern counterpart is ,u ,scuti1 which varies from magnitude #i4a to #i4f1 and runs through its two maxima and two minima in less than twenty-three hours6 ,it is a ,sirian star4 ,x ,,short-,,period ,,variable ,,stars ,another extremely interesting class of variable stars runs through the periods as punctually as the ,algol stars1 but the light is varying up and down the whole time without any period of steadiness4 ,the length1 too1 is often much greater1 though not nearly so great as that of the ,mira variables4 ,here are a few stars of this class bright enough to be observed with a binocular1 at least at maximum3 ,,southern ,,short-,,period ,,variables ---------------------------------------- --------- ,name4 ,maximum ,minimum ,period4 ,magnitude4,magnitude4 ---------------------------------------- --------- ,days4 ,w ,sagittarii #d4c #e4a #g ,pavonis #d4c #e4b #i l ,carinae #c4f #e4j #ce ,s ,crucis #f4e #g4f #d ,v ,centaurii #f4d #g4h #e ,s ,trianguli australi #f4d #g4d #f ,s ,normae #f4f #g4f #i ---------------------------------------- --------- ,the three first on the list have been discovered to be spectroscopic binaries1 the motions varying with the light1 and as this is found to be the case with all those whose motions are known1 there can be little doubt that all variables of this class are binaries4 ,their orbits1 however1 are somewhat larger than those of the ,algol variables1 and are tilted towards us so that neither star can be seen to pass in front of the other4 ,for the gradual and continual change of light cannot possibly be caused by an eclipse4 ,yet it seems clear that it is in some way connected with the revolution of two stars about one another4 ,various suggestions have been made1 such as that the revolving star is unequally bright over its surface1 and shows us now its brighter and now its duller face2 that the two pull one another out of shape when they approach most nearly2 that they are permanently elliptical1 and turn to us first the broad and then the narrow face4 ,any or all of these may play some part in the variations of the light4 ,but the most hopeful theory takes into account a very strange fact lately established1 viz4 that the variable is at its brightest not when approaching its fellow but when coming directly toward us1 and at its faintest when receding directly from us4 ,this theory is that a dark and bright star are involved in a kind of thin nebulous cloud1 and that the bright revolving star has an enveloping atmosphere4 ,as it moves through the cloud this atmosphere is continually brushed back from its advancing face1 and therefore we shall see it when coming straight towards us through a less thickness of atmosphere1 and it will look brighter than when it is retreating from us4 ,there are grave difficulties in accepting this view1 but it receives some support from the case of ,scorpii1 in which1 as we saw1 a double star is suspected1 for quite a different reason1 of being surrounded by a thin cloud4 ,and the atmosphere supposed to be surrounding the bright star may resemble the 8smoky veil0 which we know envelops our own sun1 and causes a considerable absorption of light1 for these variables are solar stars4 ,the resistance of the cloud to the motion of the revolving star ought in time to shorten its period1 and some variables have been found to be shortening their periods4 ,short-period variables are found chiefly in the ,milky ,way4 ,,xi ,,irregular ,,and ,,doubtful ,,variables ,besides these well-marked classes of long-period1 short-period1 and ,algol variables1 there are some stars which seem to vary spasmodically1 remaining sometimes for months or even for years without any change2 and there are others whose variability is suspected but has never been confirmed4 ,useful work might be done by amateurs in trying to decide the status of these doubtful stars4 ,it must be borne in mind that red stars are notoriously difficult objects4 ,two observers comparing one at the same time with the same star will often come to opposite conclusions1 showing how difficult it is to compare stars which differ much in colour4 ,whenever possible1 red comparison stars should be selected to avoid this uncertainty4 ,the second star on the list below has a very peculiar type of variation1 unlike any other except a northern star1 ,r ,coronae1 and a third recently discovered4 ,the spectra of ,,ry ,sagittarii and ,r ,coronae are also peculiar and resemble one another4 ,the following are bright southern variables suspected to vary1 or known to vary without recognised laws3 ,,southern ,,irregular ,,and ,,suspected ,,variables ---------------------------------------- ----------------------- ,name4 ,maximum ,minimum ,remarks4 ,magnitude4,magnitude4 ---------------------------------------- ----------------------- ,z ,sculptoris #f #h ,period unknown4 ,,ry ,sagittarii #f4e ,fainter ,usually steady1 but subject than #aa4e to a sudden drop at irregular intervals4 ,worth watching4 ,,rt ,capricorni #f4e ,about #h ,period probably irregular4 ,very few observations published4 ,s ,phoenicis #g4b #h4g ,observers differ4 or or ,period irregular4 #f4h #h4d ,w ,ceti #f4e #ab ,period perhaps #cff days ,t ,ceti #e4d #f4i ,irregular4 ,s ,leporis #f4e #g4e ,irregular4 ,u ,hydrae #d4e #f4c ,irregular4 ,red 8carbon star40 ,apodis #e4e #f4f ,period probably irregular4 ,r ,apodis #e4e #f4b ,suspected4 ,t ,indi #g4b #h4i ,no regular period found ---------------------------------------- ----------------------- ,,xii ,,star-,,clusters ,endlessly varied is the grouping of the stars4 ,we find solitary stars1 twin stars1 large stars with small companions1 bright stars with faint companions1 stars alike in colour and type1 stars in strongly contrasted colours1 one young1 the other aged1 stars with invisible companions1 couples close enough to touch one another1 and couples so distant that the satellite takes more than a century to revolve round its primary4 ,one or even both components of a bright pair may be themselves divisible into a closer pair1 sometimes into a whole group of stars4 ,more beautiful and wonderful still are the clusters of stars of various tints and magnitudes1 where scores1 even hundreds1 are gathered together in what to the eye is a tiny patch1 though it may in fact take light many years to cross from one side of it to the other4 ,the finest example in the heavens of this kind of cluster is ,kappa ,crucis1 near in the ,southern ,cross4#h ,it is just visible to the naked eye as a small star1 and in a binocular the main star is seen to be surrounded by a number of others2 in a telescope it is a glorious sight4 ,orange and red stars are easily distinguished in the brilliant throng1 even if we have not ,herschel's eye for colour and fail to discriminate the 8greenish-white1 green1 red1 blue-green1 and ruddy0 which made up what he likened to 8a superb piece of fancy jewellery40 ,he charted over a hundred stars of all magnitudes from #g to #ag4 ,herschel's observations at the ,cape were made between #ahcd and #ahch4 ,when ,mr4 ,russell charted the stars of ,kappa ,crucis at the ,sydney ,observatory in #ahgb1 he found #be that had not been recorded by ,herschel1 although the great reflector was much larger than the ,sydney instrument2 many of ,herschel's stars had drifted1 and five could not be found at all4 ,if changes so striking as this take place in less than forty years1 8it is evident10 as ,russell observed1 8that more attention should be bestowed on clusters40 #h ,it is easy to remember the names of the stars in the ,southern ,cross4 ,begin at the foot1 which is obviously the brightest1 and count round the ,cross in clockwise direction 1 1 1 4 is beyond in a line with 1 4 ,quite a dozen star-clusters of this kind are visible to the naked eye in the southern hemisphere1 the most striking being in ,scorpio1 where it shines as a conspicuous silvery spot just beyond the ,scorpion's tail1 midway between ,scorpii and ,sagittarii4 ,it is named ,m #g1 which means the seventh in ,messier's list of clusters and nebulae4 ,in a binocular it is seen to be a group of very many stars1 some close together1 others scattered4 ,lacaille1 with his little half-inch telescope1 counted from #ae to #bj stars1 and ,herschel1 with his large reflector1 estimated the number at #fj4 ,at ,cordoba ,observatory no less than #aci were catalogued4 ,m #f1 a little north and west of ,m #g1 is also visible to the naked eye as a nebulous patch1 and is a fine cluster4 ,about #ej stars between magnitudes eight and twelve have been photographed1 and there are doubtless many more of lesser brightness4 ,look also just above the naked-eye double in ,scorpio1 and see what appears to be a hazy star4 ,a binocular separates this into a number of small stars1 and #aej have been photographed1 of magnitudes seven to twelve4 ,it is known as h #cfeb or ,n4,g4,c4 #fbca1 the former being the number in ,sir ,john ,herschel's catalogue1 the latter in ,dreyer's ,new ,general ,catalogue of star-clusters and nebulae4 ,a little south of ,sirius is a patch of nebulous light which shows as stars in a binocular4 ,this was registered by ,messier in #agfd as a 8mass of small stars10 and is known as ,m #da4 ,webb saw the brighter stars arranged in curves and a ruddy star near the centre4 ,one hundred and forty-four stars were registered by ,gould1 of which only five are as bright as eighth magnitude4 ,in the neighbourhood of the ,cross there are quite a number of large bright clusters1 for they must be large and bright above the average to be seen by the naked eye4 ,a line passing through the shorter arm of the ,false ,cross--i4e4 from ,velorum to ,carinae1 the naked-eye double--and continued for an equal distance beyond1 leads to a white oval patch which is plainly visible to the naked eye1 and in the binocular appears like a few stars sparkling on a nebulous background4 ,with higher powers the background also is resolved into stars1 of which there are some two hundred of the fifteenth magnitude and brighter up to the eighth4 ,this is ,n4,g4,c4 #caad4 ,in the same direction is ,carinae1 a bright ,orion-type star with numerous small stars crowding close to it4 ,this is a very lovely group in a good binocular4 ,it contains about twenty stars of magnitudes between three and eight1 and with high powers appears as a brilliant1 loosely scattered cluster covering a portion of sky equal in breadth to twice the sun's apparent diameter4 ,very similar is a cluster close to the bright and richly coloured star ,x ,carinae4 ,it looks like an elliptical nebula in a binocular1 with a few stars scattered over it4 ,two hundred have been photographed4 ,near ,carinae1 the beautiful ruddy star at the foot of the ,false ,cross1 is yet another most beautiful cluster1 which contains about fifty stars of the ninth magnitude and brighter4 ,it is visible to the naked eye1 but when a telescope is turned upon it the brilliancy is startling4 ,radiant stars are scattered all over the field4 ,just east of ,puppis1 the top of the poop of ,argo1 is a fourth-magnitude star ,c of a bright orange colour1 and round it is a cluster which ,gould describes as 8extremely impressive to the naked eye40 ,ninety-two stars show on his photograph4 ,close to ,velorum 7in the ,false ,cross7 is the star ,velorum4 ,even to the naked eye the bright star 7#c mag47 is seen to be surrounded by a cluster of faint stars1 and in a binocular it is a splendid sight4 ,the number of stars is small1 but they are bright1 ten being above the ninth magnitude4 ,lastly we may mention a remarkably fine cluster which is visible in a binocular though not to the naked eye1 in the ,centaur1 among a stream of small stars between the ,cross and ,args4 ,dunlop called it 8a pretty large cluster of stars of mixt magnitudes02 ,brisbane1 8a prodigious number of small stars very close together40#i ,there are at least a hundred above the sixteenth magnitude4 #i ,these two astronomers observed at ,paramatta1 ,new ,south ,wales1 in the early part of the nineteenth century4 ,it should be noticed that nearly all these clusters are in the ,milky ,way1 and the rest are very near it1 for this is characteristic of star-clusters like these1 viz4 irregular groups containing mixed magnitudes of stars4 ,in a list of all bright objects of this kind1 only two are found as far as #cj away from the middle line of the ,galaxy1 while #hi are within #cj north or south of it4 ,there are besides #ch in the ,clouds of ,magellan1 which resemble the ,milky ,way in constitution4 ,many clusters are simply unusually dense portions of the ,milky ,way1 and we may almost say that this type forms part of it and of the ,magellan ,clouds4 ,,xiii ,,globular ,,star-,,clusters ,if ,kappa ,crucis is the finest irregular star-cluster in the sky1 ,omega ,centauri is undoubtedly the largest and most splendid of all the globular star-clusters1 for its diameter is more than twice the diameter of the famous northern cluster in ,hercules4 ,it is easily found1 being nearly in line with and ,centauri 7the two conspicuous stars just north of the ,cross7 and a little further from than is from 4 ,the cluster looks to the naked eye just like a tailless comet1 and was mistaken for one by the author when first seen4 ,in a binocular it is quite round1 the soft milky light growing gradually brighter towards the centre1 but without the slightest suggestion of irregularity1 and no appearance of stars4 ,it must have been seen by the early navigators who named the southern constellations1 but it was first discovered as a star-cluster by ,halley in the island of ,st4 ,helena4 ,most amazing is its appearance in a telescope1 for the milky disc breaks up into thousands of tiny points of light1 densely crowded1 all alike1 innumerable4 8,this most glorious object10 as ,herschel calls it1 8the noble globular cluster ,centauri1 beyond all comparison the richest and largest object of the kind in the heavens10 is evidently quite distinct from ,crucis and clusters like those described in the last chapter4 ,in form it is circular1 and the condensation towards the centre suggests that it is spherical4 ,there are some scattered members of the group lying outside the bright crowded sphere4 ,the stars are also immensely more numerous and more closely packed than in the irregular clusters1 their total number being estimated at #aj1jjj1 and #fjjj have been actually counted on photographs1 and all these in a space which looks little larger than that occupied by the sun in the sky4 ,another striking difference is that1 instead of bright and faint stars mingled together1 here they are all nearly alike and very minute4 ,curiously enough1 it is found that they belong to two magnitudes1 and two only1 the thirteenth and fifteenth1 and this seems to be a feature of all globular clusters1 as well as the form and the dense crowding of the stars4 ,herschel at first thought the stars in ,centauri 8singularly equal1 and distributed with the most exact equality1 the condensation being that of a sphere equally filled40 ,but he immediately adds3 8,looking attentively1 ,i retract what is said about the equal scattering and equal sizes of the stars4 ,there are two sizes 444 without greater or less1 and the larger stars form rings like lace-work on it40 ,in his later notes he is again doubtful1 for he thinks that the effect may be optical1 and the larger stars only knots of faint stars2 but photography has settled the question in our day4 ,yet another point of difference between globular and irregular clusters is that the latter often have wisps of nebulosity clinging about them1 but globular clusters are entirely free from it4 ,illustration3 ,,the ,,star-,,cluster #dg ,,toucani ,from ,sir ,john ,herschel's drawing ,smaller than ,centauri1 but even more beautiful in the telescope1 is the cluster #dg ,toucani1#aj which to the unaided eye appears like a fourth-magnitude star near the smaller ,cloud of ,magellan4 ,the long curve of ,grus followed southwards leads to it4 ,nearly as many stars as in ,centauri1 or about #iejj1 are here massed into a still smaller space1 so the cluster is brighter1 and is 8compressed to a blaze of light0 at the centre4 ,the two sets of stars1 which are mingled together throughout1 are of thirteenth to fifteenth and of seventeenth magnitudes respectively4 ,herschel saw the inner denser part rose-coloured while the outer was white1 but the present writer could not see this nor find anyone to confirm it to-day1 possibly because the refracting telescopes now so often used do not show colour so well as large reflectors like ,herschel's4 ,a double star of #aath magnitude1 which is conspicuous in ,herschel's drawing1 is doubtless far outside the cluster1 and only appears projected against it by perspective4 #aj ,also named ,toucani4 ,near ,aquarii there shines with the light of a sixth-magnitude star another 8magnificent ball of stars0 which has been compared to 8a heap of fine sand40 ,it is named #b ,m ,aquarii4 ,over seventy of these tightly packed balls of stars are known1 even counting only the brightest1 and their distribution is rather curious4 ,a large number 7about twenty7 occur in the ,clouds of ,magellan1 and more than half of the seventy are in the ,milky ,way1 not scattered evenly along its course1 but almost if not entirely confined to its southern part1 and chiefly gathered in a great group in its brightest portion1 where it passes through ,sagittarius1 ,ophiuchus1 and ,aquila4 ,here they are mingled with--or perhaps projected against--numerous stars of the same magnitudes2 but many balls are also found outside the ,milky ,way1 widely scattered1 and in these parts of the sky there are relatively few of the faint-magnitude stars which compose all the globular clusters4 #dg ,toucani1 for instance1 though it is near the small ,magellanic ,cloud1 stands quite apart from it1 isolated in a black sky4 ,we do not know the distances of any of these balls of stars4 ,those which have been examined spectroscopically shine like ,canopus--that is1 they are of a type intermediate between ,sirius and our sun--but the chief light comes1 of course1 from the brighter stars1 and it may be that the fainter stars mingled with them belong to a different type4 ,a remarkable fact lately discovered is that many globular clusters--but not all--contain a large number of variable stars4 ,these vary in light in a period of about a day and have a range of about one magnitude4 ,they are not of the ,algol type1 nor quite of the usual 8short-period0 types1 and it is not yet clear what is the cause of variation1 though it seems probable that 8cluster-variables0 are double stars4 ,,xiv ,,nebulae ,athwart the ,false ,cross1 from ,velorum to ,carinae1 a line passing on leads to the round white spot which we found to be a star-cluster4 ,a little further in the same direction is a larger curved white patch1 bright enough to be visible1 once it is familiar1 even after the moon has risen4 ,this is the ,great ,nebula in ,argo1 the ,keyhole ,nebula1 in which ,eta ,args once blazed out4 ,even a binocular will divide it into two parts separated by a chasm1 and will show the pearly background powdered over with many small stars4 ,but even the most powerful telescopes do not resolve this pale background into stars1 as they resolve the star-cluster just mentioned3 it remains a pearly mist1 the brighter part strangely broken by dark rifts1 the fainter1 beyond the chasm1 a tangled skein of long cloudy streaks reaching out into the darkness and gradually1 irregularly1 fading away4 ,when ,herschel found this background unresolvable into stars1 he concluded that it did not form part of the ,milky ,way1 but was at an immeasurable distance behind1 so that here he was looking right through the ,galaxy at a still more distant region of stars1 too distant and faint for his telescope to distinguish them separately4 ,but the spectroscope has taught us that these cloud-like nebulae1 though stars are often mingled with them1 are not formed of stars at all1 but of inchoate masses of faintly luminous gas2 and they cluster so thickly in the ,milky ,way1 generally avoiding other parts of the sky1 that it seems evident that they lie in it and form part of it4 ,they are also found in great numbers in the ,greater ,magellanic ,cloud4 ,if the days of the ,herschel's photography had not come to the aid of astronomers1 and ,sir ,john speaks of the feeling of despair which often almost overcame him when trying1 night after night1 to draw the 8endless details0 of this nebula1 so capricious in their forms are its curving branches and the dark spaces between1 so strangely does its brightness vary in different regions1 and so numerous are the stars scattered over it4 ,with extraordinary patience he succeeded in cataloguing the positions of over #abjj of these4 ,to compare the present aspect of the stars with his catalogue would be a laborious task1 but might lead to results of great value4 ,the curious dark oval rift in the midst of the bright part1 which he compared with a keyhole1 he found to be not entirely devoid of light1 a thin nebulous veil covering part of it2 and many of the dark lanes and holes which in small instruments look perfectly black1 are actually filled with faint stars and extremely faint nebulosity4 ,the whole region near the nebula is exceedingly rich in stars1 and also in star-clusters1 as we have already seen4 ,to quote ,herschel once again3 8,nor is it easy for language to convey a full impression of the beauty and sublimity of the spectacle it offers when viewed in a sweep1 ushered in as it is by so glorious and innumerable a procession of stars1 to which it forms a sort of climax1 justifying expressions which1 though ,i find them written in my journal1 in the excitement of the moment1 would be thought extravagant if conveyed to these pages4 ,in fact1 it is impossible for anyone with the least spark of astronomical enthusiasm about him to pass soberly in review1 with a powerful telescope and in a fine night1 that portion of the southern sky 444 such are the variety and interest of the objects he will encounter1 and such the dazzling richness of the starry ground on which they are presented to his gaze40 ,in the constellation of the ,sword-fish1 on the edge of the ,great ,cloud of ,magellan1 is another nebula1 #cj ,dorads1 the ,great ,looped ,nebula1 which is even more marvellous in complexity of structure than the ,keyhole ,nebula in ,argo4 ,no photograph can reproduce1 and no words can describe1 the filmy appearance of these nebulae as seen in a telescope4 ,the ,looped ,nebula seems to consist entirely of strangely curved and twisted streamers on a background of dark sky1 with a few sparkling stars of various brightness scattered over it4 ,at the complicated centre one of the loops forms a nearly perfect figure-of-eight1 and another takes the outline of an eye4 ,brightest of all the large gaseous nebulae is the well-known ,orion ,nebula1 in the sword of the giant4 ,a #c-;inch telescope shows the main features well1 the dark bay running into its brightest region1 the row of three brilliant stars and the 8trapezium0 of four tiny ones very close together1 and the long outlying branches which have such fantastic curves4 ,because of its comparative brightness1 its entrancing beauty1 and its position where it can be seen from all latitudes1 this nebula has been studied more than any other4 ,the first drawing of it was made in #afef1 the first photograph in #ahhj4 ,it remains a baffling mystery still1 but a few facts have emerged4 ,its distance is immeasurable3 it has been guessed at a thousand light-years4 ,it must1 therefore1 be inconceivably vast in extent1 but it is probably excessively tenuous1 like a comet's tail1 of which a million miles contain a negligible amount of matter4 ,it is almost stationary in space1 and a careful study of its form since #ageh proves that there has been no visible change1 except perhaps in the relative brightness of some of its parts4 ,yet a recent spectroscopic investigation shows that movements are taking place in different directions within the nebula1 and a slow rotation of the whole mass1 or of its brightest portion1 is suggested4 ,it is composed of faintly luminous gas1 though whether it glows from heat or from some other cause we do not know4 ,photographs of nebulae are very misleading with regard to brightness3 one must remember that they have often been exposed for many hours4 ,helium1 hydrogen1 and an unknown gas which we call nebulium are mingled together1 but not in equal quantities4 ,in some of the fainter regions of the nebula1 especially on the south and west borders1 hydrogen produces a great deal of the light2 in the brightest parts1 near the trapezium1 the glow of nebulium is much more prominent4 ,it is scarcely doubtful that many of the stars which appear to be involved in the nebula are physically connected with it1 especially since they are of a type frequently found near nebulae1 viz4 very blue ,orion-type stars with some of their hydrogen lines not dark but bright1 as in the nebula4 ,the southern hemisphere is rich in nebulae smaller but of the same kind as these three magnificent objects1 the ,keyhole1 the ,looped1 and the ,orion ,nebulae--that is1 large irregular masses of gas1 often spangled with stars--and each has some special beauty of its own2 but for most of them large telescopes are needed to grasp the faint details4 ,there is a nest of them in the northern part of ,sagittarius3 a cloudy streak visible to the naked eye1 a little north of the star ,sagittarii1 represents three nebulae and clusters close together--,m #h1 ,m #bj1 and ,m #ba4 ,the first is a wonderful combination of a bright scattered star-cluster and a gaseous nebula1 with dark rifts dividing the cloudy structure4 ,the second is the celebrated ,trifid ,nebula1 less bright and large1 but with even more striking black lanes which split the principal part into three almost separate portions4 ,many faint stars are scattered over it1 but as they are scarcely more numerous than in the surrounding regions1 most of them probably are not connected with the nebula4 ,m #ba is a star-cluster4 ,near these1 where ,sagittarius borders on ,aquila1#aa is a small but very remarkable nebula1 known from its shape as the ,horseshoe or the ,omega ,nebula 7,m #ag74 ,it has a curious mottled appearance1 with bright knots here and there4 #aa ,on ,scutum in maps where this constellation is not included in ,aquila4 ,and a little further west1 near together1 are two wonderful nebulae which surround the two stars ,rho ,ophiuchi and ,nu ,scorpii4 ,professor ,barnard1 who has studied and taken exquisite photographs of many nebulae1 considers the first of these the finest in the sky1 because of its dark1 winding lanes and the veiling of the stars in places by partly transparent nebulous matter4 ,,xv ,,other ,,types ,,of ,,nebulae ,the large irregular nebulae described in the last chapter are all more or less mingled with stars1 at least in appearance1 and it has been suggested that they are star-clusters in process of formation1 with larger and brighter masses of filmy nebulosity all about them than at later stages1 for long-exposure photographs reveal some exceedingly faint nebulosities surrounding ,kappa ,crucis and the ,pleiades and other fully-developed star-clusters4 ,but this can only be a guess until we know more about the nature of nebulae4 ,in some regions of the sky we find vast spaces thinly veiled by nebulosity so faint and transparent that it seems to have reached the very limit at which matter can exist and be recognised as such4 ,thus in the constellation of ,orion nearly all the bright stars are connected together by the vast convolutions of an exceedingly faint diffused nebula in spiral form1 the innermost curve of which ends in the ,great ,nebula of the ,sword1 and the whole region within is filled with faint light4 ,quite distinct from these nebulae are others of perfectly regular form1 very small1 purely gaseous1 without intermingling of any stars1 but usually with one bright star-like nucleus at the centre4 ,one form is the ring nebula1 of which much the best known is that in the northern constellation of the ,lyre4 ,there are1 however1 some in the south4 ,in a large telescope they appear like little golden wedding-rings against the dark sky background4 ,another regular form is the 8planetary nebula10 so called because they look much like planets in large telescopes1 being perfectly round or oval with a sharply-defined edge1 and in several cases there are handle-like appendages1 which may possibly be encircling rings1 like the rings of ,saturn4 ,these nebulae shine with a peculiar bluish-green light1 the colour of the unknown gas nebulium1 of which they are chiefly composed4 ,in ,hydra1 south of the star ,mu1 is one of the brightest and largest1 known as ,h #bg--that is1 ,no4 #bg on ,william ,herschel's list4 ,it is elliptical and of a lovely bluish colour1 with a bright nucleus exactly in the centre4 ,by means of these sharply-defined central nuclei it has been found possible to measure the approaching or receding movements of these nebulae1 and although the one just mentioned is receding from us with a speed of only #c miles a second1 their average speed is high1 amounting to #dj or #ej miles a second4 ,one in ,sagittarius is receding at more than #hj miles a second1 and another in ,lupus attains a speed of over a hundred4 ,these are movements comparable with those of stars1 but the average is higher than even for the most rapidly moving class of stars1 the red-solar and ,antarians4 ,may we1 then1 place the planetary nebulae at the end of our star-series1 since we saw that from the blue down to the red the average movements became faster and faster1 and may we believe that all stars eventually become gaseous nebulae1 as 8new stars0 seem to do8 ,but we saw that in spectrum these nebulae rather resemble the stars at the other end of the series1 the ,wolf-,rayet1 which lead directly to the hottest and brightest of all1 the ,orion stars4 ,planetary nebulae also resemble ,wolf-,rayet1 ,orion1 and ,sirian stars1 and differ from solar and red stars in that they cluster near the ,milky ,way1 and are scarcely ever found far from it4 ,their place in the universe cannot be established yet4 ,one more kind of nebula1 the most numerous of all1 remains to be mentioned1 the so-called 8white nebulae10 which do not glow green like many of the brighter planetaries1 but shine with a white light and have more or less star-like spectra1 although not even the most powerful telescopes can resolve the white cloudiness into stars4 ,the typical nebula of this class is the famous ,andromeda ,nebula1 visible to the naked eye in northern skies as a large oval spot shining softly 8like a candle shining through horn40 ,photography first disclosed the remarkable fact that it has the form of a great1 closely-wound spiral1 and further research has shown that by far the greater number of 8white nebulae0 have this form4 ,there is a very fine one in ,aquarius1#ab which has been known since #ahbd1 but visual observations gave absolutely no idea of its true form4 ,a photograph exposed for four hours in ,september #aiab showed it clearly as about two turns of a great spiral4 #ab ,n4 ,g4 ,c4 #gbic4 ,the distribution of this kind of nebula is quite different from that of the gaseous nebulae1 for1 instead of clustering towards the ,milky ,way1 they avoid it1 and especially the brightest region1 where we saw that the others most abound1 viz4 in ,scorpio1 ,sagittarius1 and ,ophiuchus4 ,on the contrary1 the largest number of these is found near the north pole of the ,galaxy--that is1 as far removed from it as possible1 in ,virgo4 ,there is1 however1 no corresponding group about the south pole of the ,galaxy4 ,one investigator has found the distance of the ,andromeda ,nebula to be twenty light-years1 but the distance and the movements of this type are difficult to discover4 ,they are evidently very different from the others1 and quite as mysterious4 ,,xvi ,,the ,,clouds ,,of ,,magellan ,one of the wonders which most attracted the attention of early explorers in the southern hemisphere1 and roused as much interest as the ,southern ,cross1 was the pair of faint clouds1 looking like detached pieces of the ,milky ,way1 which are seen in the neighbourhood of the ,south ,pole4 ,marco ,polo made a sketch of the ,greater ,cloud1 which he describes wonderingly as 8a star as big as a sack40 ,although some star-maps show short branches of ,milky ,way pointing towards the two ,clouds1 this is incorrect1 and they are quite separate from it4 ,herschel was struck by their isolation1 especially in the case of the ,little ,cloud1 which he described as situated in a 8most oppressively desolate desert10 its only neighbour being the globular cluster #dg ,toucani1 which is near1 but separated by a perfectly black sky4 ,the ,greater ,cloud is much brighter to the naked eye than the ,lesser1 and it is much more complex and interesting in the telescope4 ,it contains1 moreover1 the wonderful ,looped ,nebula1 of which we have already spoken4 ,both ,clouds consist of gaseous nebulae and star-clusters on a background of vague nebulosity and crowds of almost indistinguishable stars4 ,but the white nebulae shun the ,clouds1 just as they shun the ,milky ,way4 ,an immense number of variable stars have been discovered in the ,clouds of ,magellan1 of the same type as those in globular clusters4 ,miss ,leavitt of ,harvard ,observatory catalogued from photographs no less than #ifi in the ,lesser ,cloud and #hjj in the ,greater4 ,in the latter the greatest number of variables was found in a stream of faint stars which connects a group of star-clusters with the ,looped ,nebula1 and others occur locally in certain parts of the ,cloud1 but few are in its northern region or in parts where many of the brighter stars congregate4 ,all the variables are very faint1 the usual minimum in both ,clouds being about fourteenth magnitude1 and the maximum seldom more than one magnitude brighter4 ,a few in the ,lesser ,cloud have been found with periods unusually long for this 8cluster type0 of variables1 amounting to #cb1 #ff1 and even #abg days4 ,these longer periods seem to belong to somewhat brighter stars1 but they are quite as exact as the usual period of a few days or a single day4 ,,xvii ,,the ,,milky ,,way ,like a great river returning into itself1 the ,galaxy encircles the starry heavens1 and those who know only its northern course have no idea of its brilliance and wonderful complexity in its brightest part4 ,its light is soft1 milky1 and almost uniform1 between ,cygnus and ,sirius1 but when it enters ,argo it becomes extremely broad1 and spreads out like a river on a flat marshy plain1 in many twisting channels with spaces between4 ,where ,canopus shines on the bank there is a narrow winding ford right across its whole breadth1 as if a path had been made by the crossing of a star4 ,after this it suddenly becomes extremely narrow1 but so bright that all the light which was shining in the broad channel seems to be condensed in this narrow bed4 ,in the brightest1 richest part the ,great ,nebula of ,argo is easily distinguished by the naked eye4 ,contrasting with this and other bright condensations are black gaps1 the largest and blackest of which is the well-known ,coal-,sack near the ,southern ,cross4 ,illustration3 ,,the ,,milky ,,way ,,in ,,scorpio1 ,,lupus1 ,,and ,,ara ,photographed at ,hanover1 ,cape ,colony1 by ,bailey and ,schultz ,the river now divides4 ,one short stream1 which goes north from ,centaur towards ,antares1 is faint and soon lost2 but another northern stream is so bright and so persistent that from ,centaur to ,cygnus we may say that the ,galaxy flows in a double current4 ,this northern portion forms first the smoke of the ,altar on which the ,centaur is about to offer the ,beast1 then passes through the ,scorpion into the ,serpent-,holder1 and here1 between ,ophiuchi and ,corona ,australis1 the double stream has its greatest width4 ,the northern division soon grows dim and seems to die out1 but begins again near ,ophiuchi1 and1 curving through a little group of stars1 passes through the head of the ,eagle and forms an oval lagoon in the ,swan4 ,the southern stream passes through the ,scorpion's ,tail into ,sagittarius1 then through the ,eagle and the ,arrow till it flows close beside the northern stream in the ,swan1 and finally rejoins it in a bright patch round ,cygni4 ,except just here it is much brighter than the northern stream1 and its structure is even fuller of wonderful detail than in ,argo4 ,in ,sagittarius it consists of great rounded patches with dark spaces between4 ,the brightest of these contains the star ,sagittarii2 then follows a remarkable region of small patches and streaks1 the portion passing through ,sagittarius and ,aquila being thickly studded with nebulae4 ,this is followed by another bright patch1 rivalling that round ,sagittarii1 which involves the stars and #f ,aquilae4 ,this ends the most brilliant and wonderful part of the ,milky ,way4 ,when well seen1 as we see it in the south1 it recalls ,herschel's words1 written at the ,cape when it came into view in his telescope3 8,the real ,milky ,way is just come on in great semi-nebulous masses1 running into one another1 heaps on heaps40 ,and again3 8,the ,milky ,way is like sand1 not strewed evenly as with a sieve1 but as if flung down by handfuls1 and both hands at once40 ,what is it8 ,the ancients thought it the pathway of departed spirits1 or fiery exhalations from the earth imprisoned in the skies1 or a former road of the sun through the stars4 ,but ,democritus and some other inquiring ,greeks believed it to be the shining of multitudes of stars too faint and too close together to be seen separately1 and we know this to be the truth4 ,we know also1 from simply counting the stars in different regions of the sky1 that their numbers increase regularly as we go from north or south towards the ,milky ,way1 and stars of all magnitudes are most abundant within its course4 ,we saw also that star-clusters and certain kinds of nebulae frequent it1 while other kinds avoid it1 and that blue and white stars are the most abundant near it1 and tend to move through space in planes parallel with it1 while the redder stars are scattered and move about in all directions4 ,facts like these lead astronomers to believe that the ,milky ,way has a definite relation with all the visible universe1 that even the most distant nebula is not an outlying universe apart from ours1 but all are parts of one vast stellar system4 ,it is possible that the ,milky ,way1 which we see as a great circle1 double in one part1 is really an immense spiral1 and that we are nearest one curve of it1 the great southern division which looks so bright4 ,it may be that the spiral nebulae1 vast though they are in terms of earthly measurement1 are tiny models of one tremendous spiral which enfolds the universe with its coils4 ,,printed ,,in ,,great ,,britain ,,by ,,ballantyne1 ,,hanson ,,co4 ,,ltd4 ,,edinburgh ,,and ,,london