,,astronomical ,,curiosities ,,facts ,,and ,,fallacies ,,astronomical ,,curiosities ,,facts ,,and ,,fallacies ,,by ,j4 ,,ellard ,,gore ,,member ,,of ,,the ,,royal ,,irish ,,academy ,,fellow ,,of ,,the ,,royal ,,astronomical ,,society ,,corresponding ,,member ,,of ,,the ,,royal ,,astronomical ,,society ,,of ,,canada ,,etc4 ,,author ,,of ,,astronomical ,,essays1 ,,studies ,,in ,,astronomy1 ,,the ,,visible ,,universe1 ,,etc4 ,,london ,,chatto ,,windus #aiji ,,printed ,,by ,,william ,,clowes ,,and ,,sons1 ,,limited ,,london ,,and ,,beccles ,all rights reserved ,,preface ,the curious facts1 fallacies1 and paradoxes contained in the following pages have been collected from various sources4 ,most of the information given will not1 ,i think1 be found in popular works on astronomy1 and will1 it is hoped1 prove of interest to the general reader4 ,j4 ,e4 ,g4 ,september1 #aiji4 ,,contents ,,page ,,chapter ,i4 ,,the ,,sun #a ,,ii4 ,,mercury #aj ,,iii4 ,,venus #ag ,,iv4 ,,the ,,earth #cb ,v4 ,,the ,,moon #dh ,,vi4 ,,mars #ei ,,vii4 ,,the ,,minor ,,planets #fh ,,viii4 ,,jupiter #gd ,,ix4 ,,saturn #hd ,x4 ,,uranus ,,and ,,neptune #ia ,,xi4 ,,comets #ig ,,xii4 ,,meteors #aag ,,xiii4 ,,the ,,zodiacal ,,light ,,and ,,gegenschein #abg ,,xiv4 ,,the ,,stars #ace ,,xv4 ,,double ,,and ,,binary ,,stars #afj ,,xvi4 ,,variable ,,stars #agj ,,xvii4 ,,nebul ,,and ,,clusters #aia ,,xviii4 ,,historical #bag ,,xix4 ,,the ,,constellations #bci ,,xx4 ,,the ,,visible ,,universe #cac ,,xxi4 ,,general #cbi ,,index #cei ,,illustrations ,,page ,,al-,,sufi',s ,,earthen ,,jar #bdg ,,al-,,sufi',s ,,fishes ,,in ,,andromeda #bdi ,,astronomical ,,curiosities ,,chapter ,i ,the ,sun ,some observations recently made by ,prof4 ,w4 ,h4 ,pickering in ,jamaica1 make the value of sunlight #edj1jjj times that of moonlight4 ,this makes the sun's stellar magnitude minus #bfhc1 and that of moonlight minus #abe4 ,prof4 ,pickering finds that the light of the full moon is equal to #ajj1jjj stars of zero magnitude4 ,he finds that the moon's albedo is about #jjiji2 or in other words1 the moon reflects about one-tenth of the light which falls on it from the sun4 ,he also finds that the light of the full moon is about twelve times the light of the half moon3 a curious and rather unexpected result4 ,m4 ,c4 ,fabry found that during the total eclipse of the sun on ,august #cj1 #aije1 the light of the corona at a distance of five minutes of arc from the sun's limit1 and in the vicinity of the sun's equator1 was about #gbj candle-power4 ,comparing this with the intrinsic light of the full moon 7#bfjj candle-power7 we have the ratio of #jbh to #a4 ,he finds that the light of the sun in the zenith1 and at its mean distance from the earth1 is #ajj1jjj times greater than the light of a decimal candle placed at a distance of one metre from the eye4#a ,he also finds that sunlight is equal to #fj1jjj million times the light of ,vega4 ,this would make the sun's stellar magnitude minus #bfg1 which does not differ much from ,prof4 ,pickering's result1 given above1 and is probably not far from the truth4 ,from experiments made in #aijf at ,moscow1 ,prof4 ,ceraski found that the light of the sun's limb is only #cad to #chd times brighter than the illumination of the earth's atmosphere very near the limb4 ,this is a very unexpected result2 and considering the comparative faintness of the sun's corona during a total eclipse1 it is not surprising that all attempts to photograph it without an eclipse have hitherto failed4#b ,from ,paschen's investigations on the heat of the sun's surface1 he finds a result of #eifa 7absolute71 assuming that the sun is a perfectly black body4#c ,schuster finds that ,there is a stratum near the sun's surface having an average temperature of approximately #eejj ,c41 to which about #jc of the sun's radiation is due4 ,the remaining portion of the radiation has an intensity equal to that due to a black body having a temperature of about #fgjj ,c4 ,the above results agree fairly well with those found by the late ,dr4 ,w4 ,e4 ,wilson4#d ,the assumption of the sun being a black body seems a curious paradox2 but the simple meaning of the statement is that the sun is assumed to act as a radiator as if it were a perfectly black body heated to the high temperature given above4 ,according to ,prof4 ,langley1 the sun's photosphere is #ejjj times brighter than the molten metal in a ,bessemer convertor4#e ,observations of the sun even with small telescopes and protected by dark glasses are very dangerous to the eyesight4 ,galileo blinded himself in this way2 ,sir ,william ,herschel lost one of his eyes2 and some modern observers have also suffered4 ,the present writer had a narrow escape from permanent injury while observing the transit of ,venus1 in #ahgd1 in ,india1 the dark screen before the eyepiece of a #c-;inch telescope having blistered--that is1 partially fused during the observation4 ,mr4 ,cooper1 ,markree ,castle1 ,ireland1 in observing the sun1 used a drum of alum water and dark spectacles1 and found this sufficient protection against the glare in using his large refracting telescope of #acc-;inches aperture4 ,prof4 ,mitchell1 of ,columbia ,university 7,u4,s4,a471 finds that lines due to the recently discovered atmospherical gases argon and neon are present in the spectrum of the sun's chromosphere4 ,the evidence for the existence of krypton and xenon is1 however1 inconclusive4 ,prof4 ,mitchell suggests that these gases may possibly have reached the earth's atmosphere from the sun4 ,this would agree with the theory advanced by ,arrhenius that ionised particles are constantly being repulsed by the pressure of light1 and thus journey from one sun to another4#f ,prof4 ,young in #ahgj1 and ,dr4 ,kreusler in ,june1 #aijd1 observed the helium line ,d#c as a dark line in the spectrum of the region about a sun-spot4#g ,this famous line1 from which helium was originally discovered in the sun1 and by which it was long afterwards detected in terrestrial minerals1 usually appears as a bright line in the spectrum of the solar chromosphere and prominences4 ,it has also been seen dark by ,mr4 ,buss in sun-spot regions4#h ,the discovery of sun-spots was claimed by ,hariotte1 in #afaj1 and by ,galileo1 ,fabricius1 and ,scheiner1 in #afaa4 ,the latter wrote #hjj pages on them1 and thought they were small planets revolving round the sun6 ,this idea was also held by ,tard1 who called them ,astra ,borbonia1 and by ,c4 ,malapert1 who termed them ,sydera ,austricea4 ,but they seem to have been noticed by the ancients4 ,although in modern times there has been no extraordinary development of sun-spots at the epoch of maximum1 it is not altogether impossible that in former times these spots may have occasionally increased to such an extent1 both in number and size1 as to have perceptibly darkened the sun's light4 ,a more probable explanation of recorded sun-darkenings seems1 however1 to be the passing of a meteoric or nebulous cloud between the sun and the earth4 ,a remarkable instance of sun-darkening recorded in ,europe occurred on ,may #bb1 #ahgj1 when the sun's light was observed to be considerably reduced in a cloudless sky in the west of ,ireland1 by the late ,john ,birmingham2 at ,greenwich on the #bcrd2 and on the same date1 but at a later hour1 in ,north-,eastern ,france--a progressive manifestation1 ,mr4 ,birmingham says1 that seems to accord well with the hypothesis of moving nebulous matter4 ,a similar phenomenon was observed in ,new ,england 7,u4,s4,a471 on ,september #f1 #ahha4 ,one of the largest spots ever seen on the sun was observed in ,june1 #ahdc4 ,it remained visible for seven or eight days4 ,according to ,schwabe--the discoverer of the sun-spot period--its diameter was #gd1jjj miles1 so that its area was many times that of the earth's surface4 ,the most curious thing about this spot was that it appeared near a minimum of the sun-spot cycle6 and was therefore rather an anomalous phenomenon4 ,it was suggested by the late ,daniel ,kirkwood that this great spot was caused by the fall of meteoric matter into the sun2 and that it had possibly some connection with the great comet of #ahdc1 which approached the sun nearer than any other recorded comet1 its distance from the sun at perihelion being about #fe1jjj miles1 or less than one-third of the moon's distance from the earth4 ,this near approach of the comet to the sun occurred about three months before the appearance of the great sun-spot2 and it seems probable that the spot was caused by the downfall of a large meteorite travelling in the wake of the comet4#i ,the connection between comets and meteors is well known4 ,the so-called blackness of sun-spots is merely relative4 ,they are really very bright4 ,the most brilliant light which can be produced artificially looks like a black spot when projected on the sun's disc4 ,according to ,sir ,robert ,ball a pound of coal striking a body with a velocity of five miles a second would develop as much heat as it would produce by its combustion4 ,a body falling into the sun from infinity would have a velocity of #dej miles a second when it reached the sun's surface4 ,now as the momentum varies as the square of the velocity we have a pound of coal developing #ijb 7#dej_/e7b1 or #h1ajj times as much heat as would be produced by its combustion4 ,if the sun were formed of coal it would be consumed in about #cjjj years4 ,hence it follows that the contraction of the sun's substance from infinity would produce a supply of heat for #cjjj #hajj1 or #bd1cjj1jjj years4 ,the late ,mr4 ,proctor and ,prof4 ,young believed that the contraction theory of the sun's heat is the true and only available theory4 ,the theory is1 of course1 a sound one2 but it may now be supplemented by supposing the sun to contain a certain small amount of radium4 ,this would bring physics and geology into harmony4 ,proctor thought the sun's real globe is very much smaller than the globe we see4 ,in other words the process of contraction has gone on further than1 judging from the sun's apparent size1 we should suppose it to have done1 and therefore represents more sun work done in past ages4 ,with reference to the suggestion1 recently made1 that a portion1 at least1 of the sun's heat may be due to radium1 and the experiments which have been made with negative results1 ,mr4 ,r4 ,t4 ,strutt--the eminent physicist--has made some calculations on the subject and says1 even if all the sun's heat were due to radium1 there does not appear to be the smallest possibility that the ,becquerel radiation from it could ever be detected at the earth's surface4#aj ,the eminent ,swedish physicist ,arrhenius1 while admitting that a large proportion of the sun's heat is due to contraction1 considers that it is probably the chemical processes going on in the sun1 and not the contraction which constitute the chief source of the solar heat4#aa ,as the centre of gravity of the sun and ,jupiter lies at a distance of about #dfj1jjj miles from the sun's centre1 and the sun's radius is only #dcc1jjj miles1 it follows that the centre of gravity of the sun and planet is about #bg1jjj miles outside the sun's surface4 ,the attractions of the other planets perpetually change the position of the centre of gravity of the solar system2 but in some books on astronomy it is erroneously stated that the centre of gravity of the system is always within the sun's surface4 ,if all the planets lay on the same side of the sun at the same time 7as might possibly happen71 then the centre of gravity of the whole system would lie considerably more than #bg1jjj miles outside the sun's surface4 ,with reference to the sun's great size1 ,carl ,snyder has well said1 ,it was as if in ,vulcan's smithy the gods had moulded one giant ball1 and the planets were but bits and small shot which had spattered off as the glowing ingot was cast and set in space4 ,little man on a little part of a little earth--a minor planet1 a million of which might be tumbled into the shell of the central sun--was growing very small2 his wars1 the convulsions of a state1 were losing consequence4 ,human endeavour1 human ambitions could now scarce possess the significance they had when men could regard the earth as the central fact of the universe4#ab ,with reference to the late ,prof4 ,c4 ,a4 ,young 7,u4,s4,a47--a great authority on the sun--an ,american writer has written the following lines3-- ,the destined course of whirling worlds to trace1 ,to plot the highways of the universe1 ,and hear the morning stars their song rehearse1 ,and find the wandering comet in his place2 ,this is the triumph written in his face1 ,and in the gleaming eye that read the sun ,like open book1 and from the spectrum won ,the secrets of immeasurable space4#ac ,,chapter ,,ii ,mercury ,as the elongation of ,mercury from the sun seldom exceeds #ah1 it is a difficult object1 at least in this country1 to see without a telescope4 ,as the poet says1 the planet-- ,can scarce be caught by philosophic eye ,lost in the near effulgence of its blaze4 ,tycho ,brah1 however1 records several observations of ,mercury with the unaided vision in ,denmark4 ,it can be occasionally caught with the naked eye in this country after sunset1 when it is favourably placed for observation1 and ,i have so seen it several times in ,ireland4 ,on ,february #ai1 #ahhh1 ,i found it very visible in strong twilight near the western horizon1 and apparently brighter than an average star of the first magnitude would be in the same position4 ,in the clear air of the ,punjab sky ,i observed ,mercury on ,november #bd-bi1 #ahgb1 near the western horizon after sunset4 ,its appearance was that of a reddish star of the first magnitude4 ,on ,november #bi ,i compared its brilliancy with that of ,saturn1 which was some distance above it1 and making allowance for the glare near the horizon in which ,mercury was immersed1 its brightness appeared to me to be quite equal to that of ,saturn4 ,in ,june1 #ahgd1 ,i found it equal to ,aldebaran1 and of very much the same colour4 ,mr4 ,w4 ,f4 ,denning1 the famous observer of meteors1 states that he observed ,mercury with the naked eye about #aej times during the years #ahfh to #aije4ad ,he found that the duration of visibility after sunset is about #a;h #djm when seen in ,march1 #a;h #cjm in ,april1 and #a;h #bjm in ,may4 ,he thinks that the planet is1 at its brightest1 certainly much brighter than a first magnitude star4#ae ,in ,february1 #ahfh1 he found that its brightness rivalled that of ,jupiter1 then only #b or #c distant4 ,in ,november1 #ahhb1 it seemed brighter than ,sirius4 ,in #ahgf it was more striking than ,mars1 but the latter was then faint and at a considerable distance from the earth4 ,in #ahgh1 when ,mercury and ,venus were in the same field of view of a telescope1 ,nasmyth found that the surface brightness 7or intrinsic brightness1 as it is called7 of ,venus was at least twice as great as that of ,mercury2 and ,zllner found that from a photometric point of view the surface of ,mercury is comparable with that of the moon4 ,with reference to the difficulty of seeing ,mercury1 owing to its proximity to the sun1 ,admiral ,smyth says1 ,although ,mercury is never in opposition to the earth1 he was1 when in the house of ,mars1 always viewed by astrologers as a most malignant planet1 and one full of evil influences4 ,the sages stigmatized him as a false deceitful star 7sidus dolosum71 the eternal torment of astronomers1 eluding them as much as terrestrial mercury did the alchemists2 and ,goad1 who in #afhf published a whole folio volume full of astro-meteorological aphorisms1 unveiling the choicest secrets of nature1 contemptuously calls ,mercury a 'squinting lacquey of the sun1 who seldom shows his head in these parts1 as if he was in debt4' ,his extreme mobility is so striking that chemists adopted his symbol to denote quicksilver4#af ,prof4 ,w4 ,h4 ,pickering thinks that the shortness of the cusps 7or horns7 of ,mercury's disc indicates that the planet's atmosphere is of small density--even rarer than that of ,mars4 ,the diameter of ,mercury is usually stated at about #cjjj miles2 but a long series of measures made by ,prof4 ,see in the year #aija make the real diameter about #bgjb miles4 ,this would make the planet smaller than some of the satellites of the large planets1 probably smaller than satellites ,,iii4 and ,,iv4 of ,jupiter1 less than ,saturn's satellite ,titan1 and possibly inferior in size to the satellite of ,neptune4 ,prof4 ,pickering thinks that the density of ,mercury is about #c 7water #a74 ,dr4 ,see's observations show no noticeable falling off in the brightness of ,mercury near the limb4 ,there is therefore no evidence of any kind of atmospheric absorption in ,mercury1 and the observer gets the impression that the physical condition of the planet is very similar to that of our moon4#ag ,schrter 7#aghj-ahae7 observed markings on ,mercury1 from which he inferred that the planet's surface was mountainous1 and one of these mountains he estimated at about #aa miles in height6#ah ,but this seems very doubtful4 ,to account for the observed irregularities in the motion of ,mercury in its orbit1 ,prof4 ,newcomb thinks it possible that there may exist a ring or zone of asteroids a little outside the orbit of ,mercury and having a combined mass of one-fiftieth to one-three-hundredth of the mass of ,venus1 according to its distance from ,mercury4 ,prof4 ,newcomb1 however1 considers that the existence of such a ring is extremely improbable1 and regards it more as a curiosity than a reality4#ai ,m4 ,lo ,brenner thinks that he has seen the dark side of ,mercury1 in the same way that the dark side of ,venus has been seen by many observers4 ,in the case of ,mercury the dark side appeared darker than the background of the sky4 ,perhaps this may be due to its being projected on the zodiacal light1 or outer envelope of the sun4#bj ,mercury is said to have been occulted by ,venus in the year #agcg4ba ,but whether this was an actual occultation1 or merely a near approach does not seem to be certain4 ,the first transit of ,mercury across the sun's disc was observed by ,gassendi on ,november #f1 #afca1 and ,halley observed one on ,november #g1 #afgg1 when in the island of ,st4 ,helena4 ,seen from ,mercury1 ,venus would appear brighter than even we see it1 and as it would be at its brightest when in opposition to the sun1 and seen on a dark sky with a full face1 it must present a magnificent appearance in the midnight sky of ,mercury4 ,the earth will also form a brilliant object1 and the moon would be distinctly visible4 ,the other planets would appear very much as they do to us1 but with somewhat less brilliancy owing to their greater distance4 ,as the existence of an intra-,mercurial planet 7that is a planet revolving round the sun within the orbit of ,mercury7 seems now to be very improbable1 ,prof4 ,perrine suggests that possibly the finely divided matter which produces the zodiacal light when considered in the aggregate may be sufficient to cause the perturbations in the orbit of ,mercury4#bb ,prof4 ,newcomb1 however1 questions the exact accuracy of ,newton's law1 and seems to adopt ,hall's hypothesis that gravity does not act exactly as the inverse square of the distance1 and that the exponent of the distance is not #b1 but #bjjjjjjaegd4bc ,voltaire said1 ,if ,newton had been in ,portugal1 and any ,dominican had discovered a heresy in his inverse ratio of the squares of the distances1 he would without hesitation have been clothed in a san benito1 and burnt as a sacrifice to ,god at an auto da f4#bd ,an occultation of ,mercury by ,venus was observed with a telescope on ,may #ag1 #agcg4be ,may transits of ,mercury across the sun's disc will occur in the years #aibd1 #aieg1 and #aigj2 and ,november transits in the years #aiad1 #aibg1 and #aidj4bf ,from measurements of the disc of ,mercury during the last transit1 ,m4 ,r4 ,jonckheere concludes that the polar diameter of the planet is greater than the equatorial6 ,his result1 which is very curious1 if true1 seems to be supported by the observations of other observers4#bg ,the rotation period of ,mercury1 or the length of its day1 seems to be still in doubt4 ,from a series of observations made in the years #ahif to #aiji1 ,mr4 ,john ,mc,harg finds a period of #ajabaafb day1 or #a;d #j;h #agm #bfs#h4 ,he thinks that the planet possesses a considerable atmosphere not so clear as that of ,mars2 that its axis is very considerably tilted2 and that it has fairly large sheets of water4#bh ,,chapter ,,iii ,venus ,venus was naturally--owing to its brightness--the first of the planets known to the ancients4 ,it is mentioned by ,hesiod1 ,homer1 ,virgil1 ,martial1 and ,pliny2 and ,isaiah's remark about ,lucifer1 son of the morning 7,isaiah xiv4 #ab7 probably refers to ,venus as a morning star4 ,an observation of ,venus is found on the ,nineveh tablets of date ,b4,c4 #fhd4 ,it was observed in daylight by ,halley in ,july1 #agaf4 ,in very ancient times ,venus1 when a morning star1 was called ,phosphorus or ,lucifer1 and when an evening star ,hesperus2 but1 according to ,sir ,g4 ,c4 ,lewis1 the identity of the two objects was known so far back as #edj ,b4,c4 ,when ,venus is at its greatest brilliancy1 and appears as a morning star about ,christmas time 7which occurred in #ahhg1 and again in #ahhi71 it has been mistaken by the public for a return of the ,star of ,bethlehem4#bi ,but whatever the star of the ,magi was it certainly was not ,venus4 ,it1 seems1 indeed absurd to suppose that the wise men of the ,east should have mistaken a familiar object like ,venus for a strange apparition4 ,there seems to be nothing whatever in the ,bible to lead us to expect that the star of ,bethlehem will reappear4 ,mr4 ,j4 ,h4 ,stockwell has suggested that the ,star of ,bethlehem may perhaps be explained by a conjunction of the planets ,venus and ,jupiter which occurred on ,may #h1 ,b4,c4 #f1 which was two years before the death of ,herod4 ,from this it would follow that the ,crucifixion took place on ,april #c1 ,a4,d4 #cc4 ,but it seems very doubtful that the phenomenon recorded in the ,bible refers to any conjunction of planets4 ,chacornac found the intrinsic brightness of ,venus to be ten times greater than the most luminous parts of the moon4#cj ,but this estimate is probably too high4 ,when at its brightest1 the planet is visible in broad daylight to good eyesight1 if its exact position in the sky is known4 ,in the clear air of ,cambridge 7,u4,s4,a47 it is said to be possible to see it in this way in all parts of its orbit1 except when the planet is within #aj of the sun4#ca ,mr4 ,a4 ,cameron1 of ,yarmouth1 ,nova ,scotia1 has1 however1 seen ,venus with the naked eye three days before conjunction when the planet was only #f-a_/d from the sun4#cb ,this seems a remarkable observation1 and shows that the observer's eyesight must have been very keen4 ,in a private letter dated ,october #bb1 #ahhh1 the late ,rev4 ,s4 ,j4 ,johnson informed the present writer that he saw ,venus with the naked eye only four days before conjunction with the sun in ,february1 #ahgh1 and ,february1 #ahhf4 ,the crescent shape of ,venus is said to have been seen with the naked eye by ,theodore ,parker in ,america when he was only #ab years old4 ,other observers have stated the same thing2 but the possibility of such an observation has been much disputed in recent years4 ,in the ,chinese ,annals some records are given of ,venus having been seen in the ,pleiades4 ,on ,march #af1 ,a4,d4 #hde1 it is said that ,venus eclipsed the ,pleiades4 ,this means1 of course1 that the cluster was apparently effaced by the brilliant light of the planet4 ,computing backwards for the above date1 ,hind found that on the evening of ,march #af1 #hde1 ,venus was situated near the star ,electra2 and on the following evening the planet passed close to ,maia2 thus showing the accuracy of the ,chinese record4 ,another eclipse of the ,pleiades by ,venus is recorded in the same annals as having occurred on ,march #aj1 ,a4,d4 #ajjb4cc ,when ,venus is in the crescent phase1 that is near ,inferior conjunction with the sun1 it will be noticed1 even by a casual observer1 that the crescent is not of the same shape as that of the crescent moon4 ,the horns or cusps of the planetary crescent are more prolonged than in the case of the moon1 and extend beyond the hemisphere4 ,this appearance is caused by refraction of the sun's light through the planetary atmosphere1 and is1 in fact1 a certain proof that ,venus has an atmosphere similar to that of the earth4 ,observations further show that this atmosphere is denser than ours4 ,seen from ,venus1 the earth and moon1 when in opposition1 must present a splendid spectacle4 ,i find that the earth would shine as a star about half as bright again as ,venus at her brightest appears to us1 and the moon about equal in brightness to ,sirius6 the two forming a superb naked eye double star--perhaps the finest sight of its kind in the solar system4#cd ,some of the earlier observers1 such as ,la ,hire1 ,fontana1 ,cassini1 and ,schrter1 thought they saw evidence of mountains on ,venus4 ,schrter estimated some of these to be #bg or #bh miles in height6 but this seems very doubtful4 ,sir ,william ,herschel severely attacked these supposed discoveries4 ,schrter defended himself1 and was supported by ,beer and ,mdler1 the famous lunar observers4 ,several modern observers seem to confirm ,schrter's conclusions2 but very little is really known about the topography of ,venus4 ,the well-known ,french astronomer ,trouvelot--a most excellent observer--saw white spots on ,venus similar to those on ,mars4 ,these were well seen and quite brilliant in ,july and ,august1 #ahgf1 and in ,february and ,november1 #ahgg4 ,the observations seem to show that these spots do not 7unlike ,mars7 increase and decrease with the planet's seasons4 ,these white spots had been previously noticed by former observers1 including ,bianchini1 ,derham1 ,gruithuisen1 and ,la ,hire2 but these early observers do not seem to have considered them as snow caps1 like those of ,mars4 ,trouvelot was led by his own observations to conclude that the period of rotation of ,venus is short1 and the best result he obtained was #bc;h #dim #bhs4 ,this does not differ much from the results previously found by ,de ,vico1 ,fritsch1 and ,schrter4#ce ,a white spot near the planet's south pole was seen on several occasions by ,h4 ,c4 ,russell in ,may and ,june1 #ahgf4cf ,photographs of ,venus taken on ,march #ah and ,april #bi1 #aijh1 by ,m4 ,qunisset at the ,observatory of ,juvissy1 ,france1 show a white polar spot4 ,the spot was also seen at the same observatory by ,m4 ,a4 ,benoit on ,may #bj1 #aijc4 ,the controversy on the period of rotation of ,venus1 or the length of its day1 is a very curious one and has not yet been decided4 ,many good observers assert confidently that it is short 7about #bd hours72 while others affirm with equal confidence that it is long 7about #bbe days1 the period of the planet's revolution round the sun74 ,among the observers who favour the short period of rotation are3 ,d4 ,cassini 7#affg71 ,j4 ,cassini 7#agcj71 ,schrter 7#aghh-ic71 ,mdler 7#ahcf71 ,de ,vico 7#ahdj87 ,trouvelot 7#ahga-gi71 ,flammarion1 ,lo ,brenner1 ,stanley ,williams1 and ,j4 ,mc,harg2 and among those who support the long period are3 ,bianchini 7#agbg71 ,schiaparelli1 ,cerulli1 ,tacchini1 ,mascari1 and ,lowell4 ,some recent spectroscopic observations seem to favour the short period4 ,flammarion thinks that nothing certain can be descried upon the surface of ,venus1 and that whatever has hitherto been written regarding its period of rotation must be considered null and void2 and again he says1 ,nothing can be affirmed regarding the rotation of ,venus1 inasmuch as the absorption of its immense atmosphere certainly prevents any detail on its surface from being perceived4#cg ,the eminent ,swedish physicist ,arrhenius thinks1 however1 that the dense atmosphere and clouds of ,venus are in favour of a rapid rotation on its axis4#ch ,he thinks that the mean temperature of ,venus may not differ much from the calculated temperature #ajd ,f4 ,under these circumstances the assumption would appear plausible that a very considerable portion of the surface of ,venus1 and particularly the districts about the poles1 would be favourable to organic life4#ci ,the secondary light of ,venus1 or the visibility of the dark side1 seems to have been first mentioned by ,derham in his ,astro ,theology published in #agae4 ,he speaks of the visibility of the dark part of the planet's disc by the aid of a light of a somewhat dull and ruddy colour4 ,the date of ,derham's observation is not given1 but it seems to have been previous to the year #agad4 ,the light seems to have been also seen by a friend of ,derham4 ,we next find observations by ,christfried ,kirch1 assistant astronomer to the ,berlin ,academy of ,sciences1 on ,june #g1 #agba1 and ,march #h1 #agbf4 ,these observations are found in his original papers1 and were printed in the ,astronomische ,nachrichten1 ,no4 #aehf4 ,on the first date the telescopic image of the planet was rather tremulous1 but in #agbf he noticed that the dark part of the circle seemed to belong to a smaller circle than the illuminated portion of the disc4#dj ,the same effect was also noted by ,webb4#da ,a similar illusion is seen in the case of the crescent moon1 and this has given rise to the saying1 the old moon in the new moon's arms4 ,we next come1 in order of date1 to an observation made by ,andreas ,mayer1 ,professor of ,mathematics at ,griefswald in ,prussia4 ,the observation was made on ,october #bj1 #agei1 and the dark part of ,venus was seen distinctly by ,mayer4 ,as the planet's altitude at the time was not more than #ad above the horizon1 and its apparent distance from the sun only #aj1 the phenomenon--as ,professor ,safarik has pointed out--must have had a most unusual intensity4 ,sir ,william ,herschel makes no mention of having ever seen the secondary light of ,venus1 although he noticed the extension of the horns beyond a semicircle4 ,in the spring and summer of the year #agic1 ,von ,hahn of ,remplin in ,mecklenburg1 using excellent telescopes made by ,dollond and ,herschel1 saw the dark part of ,venus on several occasions1 and describes the light as grey verging upon brown4 ,schrter of ,lilienthal--the famous observer of the moon--saw the horns of the crescent of ,venus extended many degrees beyond the semicircle on several occasions in #aghd and #agie1 and the border of the dark part faintly lit up by a dusky grey light4 ,on ,february #ad1 #ahjf1 at #g ,p4,m4 he saw the whole of the dark part visible with an ash-coloured light1 and he was satisfied that there was no illusion4 ,on ,january #bd of the same year1 #ahjf1 ,harding at ,gttingen1 using a reflector of #i inches aperture and power #hd1 saw the dark side of ,venus shining with a pale ash-coloured light1 and very visible against the dark background of the sky4 ,the appearance was seen with various magnifying powers1 and he thought that there could be no illusion4 ,in fact the phenomenon was as evident as in the case of the moon4 ,harding again saw it on ,february #bh of the same year1 the illumination being of a reddish grey colour1 like that of the moon in a total eclipse4 ,the secondary light was also seen by ,pastorff in #ahbb1 and by ,gruithuisen in #ahbe4 ,since #ahbd observations of the light were made by ,berry1 ,browning1 ,guthrie1 ,langdon1 ,noble1 ,prince1 ,webb1 and others4 ,webb saw it with powers of #ij and #bab on a #ich-;inch mirror1 and found it equally visible when the bright crescent was hidden by a field bar4#db ,captain ,noble's observation was rather unique4 ,he found that the dark side was always distinctly and positively darker than the background upon which it is projected4 ,the light was also seen by ,lyman in ,america in #ahfg1 and by ,safarik at ,prague4 ,in #ahga the whole disc of ,venus was seen by ,professor ,winnecke4#dc ,on the other hand1 ,winnecke stated that he only saw it twice in #bd years2 and the great observers ,dawes and ,mdler never saw it at all6#dd ,various attempts have been made to explain the visibility--at times--of the dark side of ,venus4 ,the following may be mentioned#de3--7a7 ,reflected earth-light1 analogous to the dark side of the crescent moon4 ,this explanation was advocated by ,harding1 ,schrter1 and others4 ,but1 although the earth is undoubtedly a bright object in the sky of ,venus1 the explanation is evidently quite inadequate4 7#b7 ,phosphorescence of the planet's atmosphere4 ,this has been suggested by some observers4 7#c7 ,visibility by contrast1 a theory advanced by the great ,french astronomer ,arago4 7#d7 ,illumination of the planet's surface by an aurora borealis4 ,this also seems rather inadequate1 but would account for the light being sometimes visible and sometimes not4 7#e7 ,luminosity of the oceans--if there be any--on ,venus4 ,but this also seems inadequate4 7#f7 ,a planetary surface glowing with intense heat4 ,but this seems improbable4 7#g7 ,the ,kunstliche ,feuer 7artificial fire7 of ,gruithuisen1 a very fanciful theory4 ,flammarion thinks that the visibility of the dark side may perhaps be explained by its projection on a somewhat lighter background1 such as the zodiacal light1 or an extended solar envelope4#df ,it will be seen that none of these explanations are entirely satisfactory1 and the phenomenon1 if real1 remains a sort of astronomical enigma4 ,the fact that the light is visible on some occasions and not on others would render some of the explanations improbable or even inadmissible4 ,but the condition of the earth's atmosphere at times might account for its invisibility on many occasions4 ,a curious suggestion was made by ,zllner1 namely1 that if the secondary light of ,venus could be observed with the spectroscope it would show bright lines6 ,but such an observation would be one of extreme difficulty4 ,m4 ,hansky finds that the visibility of the light is greater during periods of maximum solar activity--that is1 at the maxima of sun spots4 ,this he explains by the theory of ,arrhenius1 in which electrified ions emitted by the sun cause the phenomena of terrestrial magnetic storms and auroras4 ,in the same way the dense atmosphere of ,venus is rendered more phosphorescent1 and therefore more easily visible by the increased solar activity4#dg ,this seems a very plausible hypothesis4 ,on the whole the occasional illumination of the night side of ,venus by a very brilliant aurora 7explanation 7#d7 above7 seems to the present writer to be the most probable explanation4 ,gruithuisen's hypothesis 7#g7 seems utterly improbable4 ,there is a curious apparent anomaly about the motion of ,venus in the sky4 ,although the planet's period of revolution round the sun is #bbdg days1 it remains on the same side of the sun1 as seen from the earth1 for #bij days4 ,the reason of this is that the earth is going at the same time round the sun in the same direction1 though at a slower pace2 and ,venus must continue to appear on the same side of the sun until the excess of her daily motion above that of the earth amounts to #agi1 and this at the daily rate of #cg' will be about #bij days4 ,several observations have been recorded of a supposed satellite of ,venus4 ,but the existence of such a body has never been verified4 ,in the year #ahhg1 ,m4 ,stroobant investigated the various accounts1 and came to the conclusion that in several at least of the recorded observations the object seen was certainly a star4 ,thus1 in the observation made by ,roedickoer and ,boserup on ,august #d1 #agfa1 a satellite and star are recorded as having been seen near the planet4 ,m4 ,stroobant finds that the supposed satellite was the star ,greek3 ch#d ,orionis1 and the star ,greek3 ch#c ,orionis4 ,a supposed observation of a satellite made by ,horrebow on ,january #c1 #agfh1 was undoubtedly ,greek3 th ,libr4 ,m4 ,stroobant found that the supposed motion of the satellite as seen by ,horrebow is accurately represented by the motion of ,venus itself during the time of observation4 ,in most of the other supposed observations of a satellite a satisfactory identification has also been found4 ,m4 ,stroobant finds that with a telescope of #f inches aperture1 a star of the #hth or even the #ith magnitude can be well seen when close to ,venus4#di ,on the night of ,august #ac1 #ahib1 ,professor ,barnard1 while examining ,venus with the great #cf-;inch telescope of the ,lick ,observatory1 saw a star of the #gth magnitude in the same field with the planet4 ,he carefully determined the exact position of this star1 and found that it is not in ,argelander's great catalogue1 the ,durchmusterung4 ,prof4 ,barnard finds that owing to elongation of ,venus from the sun at the time of observation the star could not possibly be an intra-,mercurial planet 7that is1 a planet revolving round the sun inside the orbit of ,mercury72 but that possibly it might be a planet revolving between the orbits of ,venus and ,mercury4 ,as the brightest of the minor planets--,ceres1 ,pallas1 ,juno1 and ,vesta--were not at the time near the position of the observed object1 the observation remains unexplained4 ,it might possibly have been a nova1 or temporary star4#ej ,scheuten is said to have seen a supposed satellite of ,venus following the planet across the sun at the end of the transit of ,june #f1 #agfa4ea ,humboldt speaks of the supposed satellite of ,venus as among the astronomical myths of an uncritical age4#eb ,an occultation of ,venus by the moon is mentioned in the ,chinese ,annals as having occurred on ,march #ai1 #cfa ,a4,d41 and ,tycho ,brah observed another on ,may #bc1 #aehg4ec ,a close conjunction of ,venus and ,regulus 7,greek3 a ,leonis7 is recorded by the ,arabian astronomer1 ,ibn ,yunis1 as having occurred on ,september #i1 #hhe ,a4,d4 ,calculations by ,hind show that the planet and star were within #b' of arc on that night1 and consequently would have appeared as a single star to the naked eye4 ,the telescope had not then been invented4#ed ,seen from ,venus1 the maximum apparent distance between the earth and moon would vary from about #e' to #ca'4ee ,it is related by ,arago that ,buonaparte1 when going to the ,luxembourg in ,paris1 where the ,directory were giving a fte in his honour1 was very much surprised to find the crowd assembled in the ,rue de ,touracour pay more attention to a region of the heavens situated above the palace than to his person or the brilliant staff that accompanied him4 ,he inquired the cause and learned that these curious persons were observing with astonishment1 although it was noon1 a star1 which they supposed to be that of the conqueror of ,italy--an allusion to which the illustrious general did not seem indifferent1 when he himself1 with his piercing eyes1 remarked the radiant body4 ,the star in question was ,venus4#ef ,,chapter ,,iv ,the ,earth ,the earth being our place of abode is1 of course1 to us the most important planet in the solar system4 ,it is a curious paradox that the moon's surface 7at least the visible portion7 is better known to us than the surface of the earth4 ,every spot on the moon's visible surface equal in size to say ,liverpool or ,glasgow is well known to lunar observers1 whereas there are thousands of square miles on the earth's surface--for example1 near the poles and in the centre of ,australia--which are wholly unknown to the earth's inhabitants2 and are perhaps likely to remain so4 ,many attempts have been made by paradoxers to show that the earth is a flat plane and not a sphere4 ,but ,m4 ,ricco has found by actual experiment that the reflected image of the setting sun from a smooth sea is an elongated ellipse4 ,this proves mathematically beyond all doubt that the surface of the sea is spherical2 for the reflection from a plane surface would be necessarily circular4 ,the theory of a flat earth is therefore proved to be quite untenable1 and all the arguments 787 of the earth flatteners have now been--like the ,french ,revolution--blown into space4 ,the pole of minimum temperature in the northern hemisphere1 or the pole of cold1 as it has been termed1 is supposed to lie near ,werchojansk in ,siberia1 where a temperature of nearly -#gj has been observed4 ,from a series of observations made at ,annapolis 7,u4,s4,a47 on the gradual disappearance of the blue of the sky after sunset1 ,dr4 ,see finds that the extreme height of the earth's atmosphere is about #acj miles4 ,prof4 ,newcomb finds that meteors first appear at a mean height of about #gd miles4#eg ,an aurora seen in ,canada on ,july #ae1 #ahic1 was observed from stations #aaj miles apart1 and from these observations the aurora was found to lie at a height of #aff miles above the earth's surface4 ,it was computed that if the auroral arch maintained an equal height above the earth its ends were #aaej miles away1 so that the magnificent sight was presented of an auroral belt in the sky with #bcjj miles between its two extremities4#eh ,luminous clouds are bright clouds sometimes seen at night near the end of ,june and beginning of ,july4 ,they appear above the northern horizon over the sun's place about midnight1 and evidently lie at a great height above the earth's surface4 ,observations made in ,germany by ,dr4 ,jesse1 and in ,england by ,mr4 ,backhouse1 in the years #ahhe-ia1 show that the height of these clouds is nearly constant at about #ea miles4#ei ,the present writer has seen these remarkable clouds on one or two occasions in ,county ,sligo1 ,ireland1 during the period above mentioned4 ,m4 ,montigny has shown that the approach of violent cyclones or other storms is heralded by an increase of scintillation 7or twinkling of the stars74 ,the effect is also very evident when such storms pass at a considerable distance4 ,he has also made some interesting observations 7especially on the star ,capella71 which show that1 not only does scintillation increase in rainy weather1 but that it is very evident1 at such times1 in stars situated at an altitude at which on other occasions it would not be perceptible at all2 thus confirming the remark of ,humboldt's with regard to the advent of the wet season in tropical countries4#fj ,in a paper on the subject of ,optical ,illusions in ,popular ,astronomy1 ,february1 #aijf1 ,mr4 ,arthur ,k4 ,bartlett1 of ,batter ,creek1 ,michigan 7,u4,s4,a471 makes the following interesting remarks3-- ,the lunar halo which by many persons is regarded as a remarkable and unexplained luminosity associated with the moon1 is to meteorological students neither a mysterious nor an anomalous occurrence4 ,it has been frequently observed and for many years thoroughly understood1 and at the present time admits of an easy scientific explanation4 ,it is an atmospheric exhibition due to the refraction and dispersion of the moon's light through very minute ice crystals floating at great elevations above the earth1 and it is explained by the science of meteorology1 to which it properly belongs2 for it is not of cosmical origin1 and in no way pertains to astronomy1 as most persons suppose1 except as it depends on the moon1 whose light passing through the atmosphere1 produces the luminous halo1 which as will be seen1 is simply an optical illusion1 originating1 not in the vicinity of the moon--two hundred and forty thousand miles away--but just above the earth's surface1 and within the aqueous envelope that surrounds it on all sides4444 ,a halo may form round the sun as well as the moon 444 but a halo is more frequently noticed round the moon for the reason that we are too much dazzled by the sun's light to distinguish faint colours surrounding its disc1 and to see them it is necessary to look through smoked glass1 or view the sun by reflection from the surface of still water1 by which its brilliancy is very much reduced4444 ,a 'corona' is an appearance of faintly coloured rings often seen around the sun and moon when a light fleecy cloud passes over them1 and should not be mistaken for a halo1 which is much larger and more complicated in its structure4 ,these two phenomena are frequently confounded by inexperienced observers4 ,with these remarks the present writer fully concurs4 ,mr4 ,bartlett adds-- ,as a halo is never seen except when the sky is hazy1 it indicates that moisture is accumulating in the atmosphere which will form clouds1 and usually result in a storm4 ,but the popular notion that the number of bright stars visible within the circle indicates the number of days before the storm will occur1 is without any foundation whatever1 and the belief is almost too absurd to be refuted4 ,in whatever part of the sky a lunar halo is seen1 one or more bright stars are always sure to be noticed inside the luminous ring1 and the number visible depends entirely upon the position of the moon4 ,moreover1 when the sky within the circle is examined with even a small telescope1 hundreds of stars are visible where only one1 or perhaps two or three1 are perceived with the naked eye4 ,it is possible to have five ,sundays in ,february 7the year must of course be a leap year74 ,this occurred in the year #ahhj1 ,sunday falling on ,february #a1 #h1 #ae1 #bb1 and #bi4 ,but this will not happen again till the year #aibj4 ,no century year 7such as #aijj1 #bjjj1 etc47 could possibly have five ,sundays in ,february1 and the ,rev4 ,richard ,campbell1 who investigated this matter1 finds the following sequence of years in which five ,sundays occur in ,february3 #afjd1 #afcb1 #affj1 #afhh1 #agbh1 #agef1 #aghd1 #ahbd1 #aheb1 #ahhj1 #aibj1 #aidh1 #aigf4fa ,in an article on ,the ,last ,day and ,year of the ,century3 ,remarks on ,time ,reckoning1 in ,nature1 ,september #aj1 #ahif1 ,mr4 ,w4 ,t4 ,lynn1 the eminent astronomer1 says1 ,the late ,astronomer ,royal1 ,sir ,george ,airy1 once received a letter requesting him to settle a dispute which had arisen in some local debating society1 as to which would be the first day of the next century4 ,his reply was1 ',a very little consideration will suffice to show that the first day of the twentieth century will be ,january #a1 #aija4' ,simple as the matter seems1 the fact that it is occasionally brought into question shows that there is some little difficulty connected with it4 ,probably1 however1 this is in a great measure due to the circumstance that the actual figures are changed on ,january #a1 #aijj1 the day preceding being ,december #ca1 #ahii4 ,a century is a very definite word for an interval respecting which there is no possible room for mistake or difference of opinion4 ,but the date of its ending depends upon that of its beginning4 ,our double system of backward and forward reckoning leads to a good deal of inconvenience4 ,our reckoning supposes 7what we know was not the case1 but as an era the date does equally well7 that ,christ was born at the end of ,b4,c4 #a4 ,at the end of ,a4,d4 #a1 therefore1 one year had elapsed from the event1 at the end of ,a4,d4 #ajj1 one century1 and at the end of #aijj1 nineteen centuries4444 ,it is clear1 then1 that the year1 as we call it1 is an ordinal number1 and that #aijj years from the birth of ,christ 7reckoning as we do from ,b4,c4 #a7 will not be completed until the end of ,december #ca in that year1 the twentieth century beginning with ,january #a1 #aija1 that is 7to be exact7 at the previous midnight1 when the day commences by civil reckoning4 ,with these remarks of ,mr4 ,lynn ,i fully concur1 and1 so far as ,i know1 all astronomers agree with him4 ,as the discussion will probably again arise at the end of the twentieth century1 ,i would like to put on record here what the scientific opinion was at the close of the nineteenth century4 ,prof4 ,e4 ,rutherford1 the well-known authority on radium1 suggests that possibly radium is a source of heat from within the earth4 ,traces of radium have been detected in many rocks and soils1 and even in sea water4 ,calculation shows that the total amount distributed through the earth's crust is enormously large1 although relatively small compared with the annual output of coal for the world4 ,the amount of radium necessary to compensate for the present loss of heat from the earth corresponds to only five parts in one hundred million millions per unit mass1 and the observations of ,elster and ,gertel show that the radio-activity observed in soils corresponds to the presence of about this proportion of radium4#fb ,the earth has #ab different motions4 ,these are as follows3-- #a4 ,rotation on its axis1 having a period of #bd hours4 #b4 ,revolution round the sun2 period #cfe-a_/d days4 #c4 ,precession2 period of about #be1gfe years4 #d4 ,semi-lunar gravitation2 period #bh days4 #e4 ,nutation2 period #ah-a_/b years4 #f4 ,variation in obliquity of the ecliptic2 about #dg in #ajj years4 #g4 ,variation of eccentricity of orbit4 #h4 ,change of line of apsides2 period about #ba1jjj years4 #i4 ,planetary perturbations4 #aj4 ,change of centre of gravity of whole solar system4 #aa4 ,general motion of solar system in space4 #ab4 ,variation of latitude with several degrees of periodicity4#fc ,an amusing story has been told which affords a good illustration of the ignorance and popular notions regarding the tides prevailing even among persons of average intelligence4 ',tell me1' said a man to an eminent living ,english astronomer not long ago1 'is it still considered probable that the tides are caused by the moon8' ,the man of science replied that to the best of his belief it was1 and then asked in turn whether the inquirer had any serious reason for questioning the relationship4 ',well1 ,i don't know1' was the answer2 'sometimes when there is no moon there seems to be a tide all the same4'6#fd ,with reference to the force of gravitation1 on the earth and other bodies in the universe1 ,mr4 ,william ,b4 ,taylor has well said1 ,with each revolving year new demonstrations of its absolute precision and of its universal domination serves only to fill the mind with added wonder and with added confidence in the stability and the supremacy of the power in which has been found no variableness neither shadow of turning1 but which--the same yesterday1 to-day and for ever-- ,lives through all life1 extends through all extent1 ,spreads undivided1 operates unspent4#fe ,with reference to the habitability of other planets1 ,tennyson has beautifully said-- ,venus near her6 smiling downwards at this earthlier earth of ours1 ,closer on the sun1 perhaps a world of never fading flowers4 ,hesper1 whom the poets call'd the ,bringer home of all good things2 ,all good things may move in ,hesper2 perfect people1 perfect kings4 ,hesper--,venus--were we native to that splendour1 or in ,mars1 ,we should see the globe we groan in fairest of their evening stars4 ,could we dream of war and carnage1 craft and madness1 lust and spite1 ,roaring ,london1 raving ,paris1 in that spot of peaceful light8 ,might we not in glancing heavenward on a star so silver fair1 ,yearn and clasp the hands1 and murmur1 ',would to ,god that we were there6' ,the ancient ,greek writer1 ,diogenes ,laertius1 states that ,anaximander 7#faj-edg ,b4,c47 believed that the earth was a sphere4 ,the ,greek words are3 ,greek3 misn te tn gn keisthai1 kentry taxin epechousan ousan sphairoeid4#ff ,with reference to the ,aurora ,borealis1 the exact nature of which is not accurately known1 a good story used to be told some years ago of a candidate who1 undergoing the torture of a viv voce examination1 was unable to reply satisfactorily to any of the questions asked4 ',come1 sir1' said the examiner1 with the air of a man asking the simplest question1 'explain to me the cause of the aurora borealis4' ',sir1' said the unhappy aspirant for physical honours1 ',i could have explained it perfectly yesterday1 but nervousness has1 ,i think1 made me lose my memory4' ',this is very unfortunate1' said the examiner2 'you are the only man who could have explained this mystery1 and you have forgotten it4'#fg ,this was written in the year #ahii1 and probably the phenomenon of the aurora remains nearly as great a mystery to-day4 ,in #ahci1 ,,mm4 ,bravais and ,lottin made observations on the aurora in ,norway in about ,n4 latitude #gj4 ,bravais found the height to be between #fb and #ic miles above the earth's surface4 ,the cause of the so-called ,glacial ,epoch in the earth's history has been much discussed4 ,the ,russian physicist1 ,rogovsky1 has advanced the following theory-- ,if we suppose that the temperature of the sun at the present time is still increasing1 or at least has been increasing until now1 the glacial epoch can be easily accounted for4 ,formerly the earth had a high temperature of its own1 but received a lesser quantity of heat from the sun than now2 on cooling gradually1 the earth's surface attained such a temperature as caused a great part of the surface of the northern and southern hemispheres to be covered with ice2 but the sun's radiation increasing1 the glaciers melted1 and the climatic conditions became as they are now4 ,in a word1 the temperature of the earth's surface is a function of two quantities3 one decreasing 7the earth's own heat71 and the other increasing 7the sun's radiation71 and consequently there may be a minimum1 and this minimum was the glacial epoch1 which1 as shown by recent investigations1 those of ,luigi de ,marchi 7,report of ,g4 ,schiaparelli1 ,meteorolog4 ,zeitschr41 #cj1 #acj-acf1 #ahie71 are not local1 but general for the whole earth 7see also ,m4 ,neumahr1 ,erdegeschicht74#fh ,prof4 ,percival ,lowell thinks that the life of geological palozoic times was supported by the earth's internal heat1 which maintained the ocean at a comparatively warm temperature4#fi ,the following passage in the ,book of the ,maccabees may possibly refer to an aurora-- ,now about this time ,antiochus made his second inroad into ,egypt4 ,and it so befell that throughout all the city1 for the space of almost forty days1 there appeared in the midst of the sky horsemen in swift motion1 wearing robes inwrought with gold and carrying spears1 equipped in troops for battle2 and drawing of swords2 and on the other side squadrons of horse in array2 and encounters and pursuits of both armies2 and shaking of shields1 and multitudes of lances1 and casting of darts1 and flashing of golden trappings1 and girding on of all sorts of armour4 ,wherefore all men besought that the vision might have been given for food4#gj ,according to ,laplace the decrease of the mean heat of the earth during a period of #bjjj years has not1 taking the extremist limits1 diminished as much as #a_/cjjth of a degree ,fahrenheit4#ga ,from his researches on the cause of the ,precession of the ,equinoxes1 ,laplace concluded that the motion of the earth's axis is the same as if the whole sea formed a solid mass adhering to its surface4#gb ,laplace found that the major 7or longer7 axis of the earth's orbit coincided with the line of ,equinoxes in the year #dajg ,b4,c4 ,the earth's perigee then coincided with the autumnal equinox4 ,the epoch at which the major axis was perpendicular to the line of equinoxes fell in the year #abej ,a4,d4#gc ,leverrier has found the minimum eccentricity of the earth's orbit round the sun to be #jjjdg2 so that the orbit will never become absolutely circular1 as some have imagined4 ,laplace says-- ,astronomy considered in its entirety is the finest monument of the human mind1 the noblest essay of its intelligence4 ,seduced by the illusions of the senses and of self-pride1 for a long time man considered himself as the centre of the movement of the stars2 his vain-glory has been punished by the terrors which his own ideas have inspired4 ,at last the efforts of several centuries brushed aside the veil which concealed the system of the world4 ,we discover ourselves upon a planet1 itself almost imperceptible in the vast extent of the solar system1 which in its turn is only an insensible point in the immensity of space4 ,the sublime results to which this discovery has led should suffice to console us for our extreme littleness1 and the rank which it assigns to the earth4 ,let us treasure with solicitude1 let us add to as we may1 this store of higher knowledge1 the most exquisite treasure of thinking beings4#gd ,with reference to probable future changes in climate1 the great physicist1 ,arrhenius1 says-- ,we often hear lamentation that the coal stored up in the earth is wasted by the present generation without any thought of the future1 and we are terrified by the awful destruction of life and property which has followed the volcanic eruptions of our days4 ,we may find a kind of consolation in the consideration that here1 as in every other case1 there is good mixed with evil4 ,by the influence of the increasing percentage of carbonic acid in the atmosphere1 we may hope to enjoy ages with more equable and better climates1 especially as regards the colder regions of the earth1 ages when the earth will bring forth much more abundant crops than at present1 for the benefit of rapidly propagating mankind4#ge ,the night of ,july #a1 #aijh1 was unusually bright4 ,this was noticed in various parts of ,england and ,ireland1 and by the present writer in ,dublin4 ,humboldt states that at the time of the new moon at midnight in #agdc1 the phosphorescence was so intense that objects could be distinctly recognized at a distance of more than #fjj feet4#gf ,an interesting proof of the earth's rotation on its axis has recently been found4 ,in a paper in the ,proceedings of the ,vienna ,academy 7,june1 #aijh7 by ,herr ,tumlirz1 it is shown mathematically that if a liquid is flowing outwards between two horizontal discs1 the lines of flow will be strictly straight only if the discs and vessel be at rest1 and will assume certain curves if that vessel and the discs are in rotation1 as1 for example1 due to the earth's rotation4 ,an experimental arrangement was set up with all precautions1 and the stream lines were marked with coloured liquids and photographed4 ,these were in general accord with the predictions of theory and the supposition that the earth is rotating about an axis4#gg ,in a book published in #aije entitled ,the ,rational ,almanac1 by ,moses ,b4 ,cotsworth1 of ,york1 the author states that 7p4 #cig71 ,the explanation is apparent from the ,great ,pyramid's ,slope1 which conclusively proves that when it was built the latitude of that region was #ga more than at present4 ,egyptian ,memphis now near ,cairo was then in latitude #cga1 where ,asia ,minor now ranges1 whilst ,syria would then be where the ,caucasus regions now experience those rigorous winters formerly experienced in ,syria4 ,but the reality of this comparatively great change of latitude in the position of the ,great ,pyramid can be easily disproved4 ,pytheas of ,marseilles--who lived in the time of ,alexander the ,great1 about #ccj ,b4,c4--measured the latitude of ,marseilles by means of a gnomon1 and found it to be about #db #ef'-a_/b4 ,as the present latitude of ,marseilles is #dc #ag' #ej1 no great change in the latitude could have taken place in over #bjjj years4#gh ,from this we may conclude that the latitude of the ,great ,pyramid has not changed by #ga since its construction4 ,there is1 it is true1 a slow diminution going on in the obliquity of the ecliptic 7or inclination of the earth's axis71 but modern observations show that this would not amount to as much as one degree in #fjjj years4 ,eudemus of ,rhodes--a disciple of ,aristotle 7who died in #cbb ,b4,c47--found the obliquity of the ecliptic to be #bd1 which differs but little from its present value1 #bc #bg'4 ,al-,sufi in the tenth century measured the latitude of ,schiraz in ,persia1 and found it #bi #cf'4 ,its present latitude is #bi #cf' #cj1gi so that evidently there has been no change in the latitude in #ijj years4 ,,chapter ,v ,the ,moon ,the total area of the moon's surface is about equal to that of ,north and ,south ,america4 ,the actual surface visible at any one time is about equal to ,north ,america4 ,the famous lunar observer1 ,schrter1 thought that the moon had an atmosphere1 but estimated its height at only a little over a mile4 ,its density he supposed to be less than that of the vacuum in an air-pump4 ,recent investigations1 however1 seem to show that owing to its small mass and attractive force the moon could not retain an atmosphere like that of the earth4 ,prof4 ,n4 ,s4 ,shaler1 of ,harvard 7,u4,s4,a471 finds from a study of the moon 7from a geological point of view7 with the #ae-;inch refractor of the ,harvard ,observatory1 that our satellite has no atmosphere nor any form of organic life1 and he believes that its surface was brought to its present condition before the earth had even a solid crust4#hj ,there is a curious illusion with reference to the moon's apparent diameter referred to by ,proctor4#ha ,if1 when the moon is absent in the winter months1 we ask a person whether the moon's diameter is greater or less than the distance between the stars ,greek3 d and ,greek3 e1 and ,greek3 e and ,greek3 z ,orionis1 the three well-known stars in the belt of ,orion1 the answer will probably be that the moon's apparent diameter is about equal to each of these distances4 ,but in reality the apparent distance between ,greek3 d and ,greek3 e ,orionis 7or between ,greek3 e and ,greek3 z1 which is about the same7 is more than double the moon's apparent diameter4 ,this seems at first sight a startling statement2 but its truth is1 of course1 beyond all doubt and is not open to argument4 ,proctor points out that if a person estimates the moon as a foot in diameter1 as its apparent diameter is about half a degree1 this would imply that the observer estimates the circumference of the star sphere as about #gbj feet 7#cfj #b71 and hence the radius 7or the moon's distance from the earth7 about #aae feet4 ,but in reality all such estimates have no scientific 7that is1 accurate7 meaning4 ,some of the ancients1 such as ,aristotle1 ,cicero1 and ,heraclitus1 seem to have estimated the moon's apparent diameter at about a foot4#hb ,this shows that even great minds may make serious mistakes4 ,it has been stated by some writer that the moon as seen with the highest powers of the great ,yerkes telescope 7#dj inches aperture7 appears just as it would be seen with the naked eye if it were suspended #fj miles over our heads4 ,but this statement is quite erroneous4 ,the moon as seen with the naked eye or with a telescope shows us nearly a whole hemisphere of its surface4 ,but if the eye were placed only #fj miles from the moon's surface1 we should see only a small portion of its surface4 ,in fact1 it is a curious paradox that the nearer the eye is to a sphere the less we see of its surface6 ,the truth of this will be evident from the fact that on a level plain an eye placed at a height1 say #e feet1 sees a very small portion indeed of the earth's surface1 and the higher we ascend the more of the surface we see4 ,i find that at a distance of #fj miles from the moon's surface we should only see a small portion of its visible hemisphere 7about #a_/ijth74 ,the lunar features would also appear under a different aspect4 ,the view would be more of a landscape than that seen in any telescope4 ,this view of the matter is not new4 ,it has been previously pointed out1 especially by ,m4 ,flammarion and ,mr4 ,whitmell1 but its truth is not1 ,i think1 generally recognized4 ,prof4 ,newcomb doubts whether with any telescope the moon has ever been seen so well as it would be if brought within #ejj miles of the earth4 ,a relief map of the moon #ai feet in diameter was added1 in #ahih1 to the ,field ,columbian ,museum 7,u4,s4,a474 ,it was prepared with great care from the lunar charts of ,beer and ,mdler1 and ,dr4 ,schmidt of the ,athens ,observatory1 and it shows the lunar features very accurately4 ,its construction took five years4 ,on a photograph of a part of the moon's surface near the crater ,eratosthenes1 ,prof4 ,william ,h4 ,pickering finds markings which very much resemble the so-called canals of ,mars4 ,the photograph was taken in ,jamaica1 and a copy of it is given in ,prof4 ,pickering's book on the ,moon1 and in ,popular ,astronomy1 ,february1 #aijd4 ,experiments made in ,america by ,messrs4 ,stebbins and ,f4 ,c4 ,brown1 by means of selenium cells1 show that the light of the full moon is about nine times that of the half moon2#hc and that the moon is brighter between the first quarter and full than in the corresponding phase after full moon4 ,they also find that the light of the full moon is equal to #jbc candle power1#hc that is1 according to the method of measurement used in ,america1 its light is equal to #jbc of a standard candle placed at a distance of one metre 7#cicg inches7 from the eye4#hd ,mr4 ,h4 ,h4 ,kimball finds that no less than #eb per cent4 of the observed changes in intensity of the earth-shine visible on the moon when at or near the crescent phase is due to the eccentricity of the lunar orbit1 and this is probably much greater than could be expected from any increase or diminution in the average cloudiness over the hemisphere of the earth reflecting light to the moon4#he ,the moon maiden is a term applied to a fancied resemblance of a portion of the ,sinus ,iridum to a female head4 ,it forms the promontory known as ,cape ,heraclides1 and may be looked for when the moon's age is about #aa days4 ,mr4 ,c4 ,j4 ,caswell1 who observed it on ,september #bi1 #ahie1 describes it as resembling a beautiful silver statuette of a graceful female figure with flowing hair4 ,m4 ,landerer finds that the angle of polarization of the moon's surface--about #cc--;agrees well with the polarizing angle for many specimens of igneous rocks 7#cj #ea' to #cc #df'74 ,the polarizing angle for ice is more than #cg1 and this fact is opposed to the theories of lunar glaciation advanced by some observers4#hf ,kepler states in his ,somnium that he saw the moon in the crescent phase on the morning and evening of the same day 7that is1 before and after conjunction with the sun74 ,kepler could see #ad stars in the ,pleiades with the naked eye1 so his eyesight must have been exceptionally keen4 ,investigations on ancient eclipses of the moon show that the eclipse mentioned by ,josephus as having occurred before the death of ,herod is probably that which took place on ,september #ae1 ,b4,c4 #e4 ,this occurred about #i4de p4m42 and probably about six months before the death of ,herod 7,st4 ,matthew ii4 #ae74 ,the total lunar eclipse which occurred on ,october #d1 #ahhd1 was remarkable for the almost total disappearance of the moon during totality4 ,one observer says that in the open air1 if one had not known exactly where to look for it1 one might have searched for some time without discovering it4 ,i speak of course of the naked eye appearance4#hg ,on the other hand the same observer1 speaking of the total eclipse of the moon on ,august #bc1 #ahgg1 which was a bright one1 says-- ,the moon even in the middle of the total phase was a conspicuous object in the sky1 and the ruddy colour was well marked4 ,in the very middle of the eclipse the degree of illumination was as nearly as possible equal all round the edge of the moon1 the central parts being darker than those near the edge4 ,in ,roger de ,hovedin's ,chronicle 7,a4,d4 #gef7 an account is given of the occultation of a bright star1 by the moon during a total eclipse4 ,this is confirmed by ,simeon of ,durham1 who also dates the eclipse ,a4,d4 #gef4 ,this is1 however1 a mistake1 the eclipse having occurred on the evening of ,november #bc1 ,a4,d4 #gee4 ,calvisius supposed that the occulted star might have been ,aldebaran4 ,pingr1 however1 showed that this was impossible1 and ,struyck1 in #agdj1 showed that the planet ,jupiter was the star referred to by the early observer4 ,further calculations by ,hind 7#ahhe7 show conclusively that ,struyck was quite correct1 and that the phenomenon described in the old chronicles was the occultation of ,jupiter by a totally eclipsed moon--a rather unique phenomenon4#hh ,an occultation of ,mars by the moon is recorded by the ,chinese1 on ,february #ad1 ,b4,c4 #fi1 and one of ,venus1 on ,march #cj1 ,a4,d4 #cfa4 ,these have also been verified by ,hind1 and his calculations show the accuracy of these old ,chinese records4 ,it has been suggested that the moon may possibly have a satellite revolving round it1 as the moon itself revolves round the earth4 ,this would1 of course1 form an object of great interest4 ,during the total lunar eclipses of ,march #aj and ,september #c1 #ahie1 a careful photographic search was made by ,prof4 ,barnard for a possible lunar satellite4 ,the eclipse of ,march #aj was not very suitable for the purpose owing to a hazy sky1 but that of ,september #c was entirely satisfactory1 as the sky was very clear1 and the duration of totality was very long4 ,on the latter occasion six splendid photographs were obtained of the total phase with a #f-;inch ,willard lens4 ,the result was that none of these photographs show anything which might be taken for a lunar satellite1 at least any satellite as bright as the #ajth or #abth magnitude4 ,it is1 of course1 just possible that the supposed satellite might have been behind the moon during the totality4 ,with reference to the attraction between the earth and moon1 ,sir ,oliver ,lodge says-- ,the force with which the moon is held in its orbit would be great enough to tear asunder a steel rod #djj miles thick1 with a tenacity of #cj tons to the square inch1 so that if the moon and earth were connected by steel instead of gravity1 a forest of pillars would be necessary to whirl the system once a month round their common centre of gravity4 ,such a force necessarily implies enormous tensure or pressure in the medium4 ,maxwell calculates that the gravitational stress near the earth1 which we must suppose to exist in the invisible medium1 is #cjjj times greater than what the strongest steel can stand1 and near the sun it should be #bejj times as great as that4#hi ,with reference to the names given to craters on the moon1 ,prof4 ,w4 ,h4 ,pickering says1#ij ,the system of nomenclature is1 ,i think1 unfortunate4 ,the names of the chief craters are generally those of men who have done little or nothing for selenography1 or even for astronomy1 while the men who should be really commemorated are represented in general by small and unimportant craters1 and again-- ,a serious objection to the whole system of nomenclature lies in the fact that it has apparently been used by some selenographers1 from the earliest times up to the present1 as a means of satisfying their spite against some of their contemporaries4 ,under the guise of pretending to honour them by placing their names in perpetuity upon the moon1 they have used their names merely to designate the smallest objects that their telescopes were capable of showing4 ,an interesting illustration of this point is found in the craters of ,galileo and ,riccioli1 which lie close together on the moon4 ,it will be remembered that ,galileo was the discoverer of the craters on the moon4 ,both names were given by ,riccioli1 and the relative size and importance of the craters ,riccioli large1 and ,galileo very small probably indicates to us the relative importance that he assigned to the two men themselves4 ,other examples might be quoted of craters named in the same spirit after men still living4444 ,with the exception of ,maedler1 one might almost say1 the more prominent the selenographer the more insignificant the crater4 ,the mathematical treatment of the lunar theory is a problem of great difficulty4 ,the famous mathematician1 ,euler1 described it as incredibile stadium atque indefessus labor4#ia ,with reference to the earth-shine on the moon when in the crescent phase1 ,humboldt says1 ,lambert made the remarkable observation 7#adth of ,february1 #aggd7 of a change of the ash-coloured moonlight into an olive-green colour1 bordering upon yellow4 ,the moon1 which then stood vertically over the ,atlantic ,ocean1 received upon its night side the green terrestrial light1 which is reflected towards her when the sky is clear by the forest districts of ,south ,america4#ib ,arago said1 ,il n'est donc pas impossible1 malgr tout ce qu'un pareil rsultat exciterait de surprise au premier coup d'oeil qu'un jour les mtorologistes aillent puiser dans l'aspect de la ,lune des notions prcieuses sur l'etat moyen de diaphanit de l'atmosphre terrestre1 dans les hemisphres qui successivement concurrent la production de la lumire cendre4#ic ,the earth-shine on the new moon was successfully photographed in ,february1 #ahie1 by ,prof4 ,barnard at the ,lick ,observatory1 with a #f-;inch ,willard portrait lens4 ,he says-- ,the earth-lit globe stands out beautifully round1 encircled by the slender crescent4 ,all the 'seas' are conspicuously visible1 as are also the other prominent features1 especially the region about ,tycho4 ,aristarchus and ,copernicus appear as bright specks1 and the light streams from ,tycho are very distinct4#id ,kepler found that the moon completely disappeared during the total eclipse of ,december #i1 #afja1 and ,hevelius observed the same phenomenon during the eclipse of ,april #be1 #afdb1 when not a vestige of the moon could be seen4#ie ,in the total lunar eclipse of ,june #aj1 #ahaf1 the moon during totality was not visible in ,london1 even with a telescope6#ie ,the lunar mountains are relatively much higher than those on the earth4 ,beer and ,mdler found the following heights3 ,drfel1 #bc1agd feet2 ,newton1 #bb1ada2 ,casatus1 #ba1ajb2 ,curtius1 #bj1fcb2 ,callippus1 #ah1idf2 and ,tycho1 #ah1gdh feet4#if ,taking the earth's diameter at #giab miles1 the moon's diameter1 #bafc miles1 and the height of ,mount ,everest as #bi1jjj feet1 ,i find that ,everest #a ,drfel #a ---------------- ----1 and --------------- --- ,earth's diameter #addj moon's diameter #dib ,from which it follows that the lunar mountains are proportionately about three times higher than those on the earth4 ,according to an hypothesis recently advanced by ,dr4 ,see1 all the satellites of the solar system1 including our moon1 were captured by their primaries4 ,he thinks1 therefore1 that the moon came to earth from heavenly space4#ig ,,chapter ,,vi ,mars ,mars was called by the ancients the vanishing star1 owing to the long periods during which it is practically invisible from the earth4#ih ,it was also called ,greek3 puroeis and ,hercules4 ,i have seen it stated in a book on the ,solar ,system by a well-known astronomer that the axis of ,mars is inclined to the plane of the orbit at an angle of #bd #ej'6 ,but this is quite erroneous4 ,the angle given is the angle between the plane of the planet's equator and the plane of its orbit1 which is quite a different thing4 ,this angle1 which may be called the obliquity of ,mars' ecliptic1 does not differ much from that of the earth4 ,lowell finds it #bc #ac' from observations in #aijg4ii ,the late ,mr4 ,proctor thought that ,mars is far the reddest star in the heavens2 ,aldebaran and ,antares are pale beside him4#ajj ,but this does not agree with my experience4 ,antares is to my eye quite as red as ,mars4 ,its name is derived from two ,greek words implying redder than ,mars4 ,the colour of ,aldebaran is1 ,i think1 quite comparable with that of the ruddy planet4 ,in the telescope the colour of ,mars is1 ,i believe1 more yellow than red1 but ,i have not seen the planet very often in a telescope4 ,sir ,john ,herschel suggested that the reddish colour of ,mars may possibly be due to red rocks1 like those of the ,old ,red ,sandstone1 and the red soil often associated with such rocks1 as ,i have myself noticed near ,torquay and other places in ,devonshire4 ,the ruddy colour of ,mars was formerly thought to be due to the great density of its atmosphere4 ,but modern observations seem to show that the planet's atmosphere is1 on the contrary1 much rarer than that of the earth4 ,the persistent visibility of the markings on its surface shows that its atmosphere cannot be cloud-laden like ours2 and the spectroscope shows that the water vapour present is--although perceptible--less than that of our terrestrial envelope4 ,the existence of water vapour is clearly shown by photographs of the planet's spectrum taken by ,mr4 ,slipher at the ,lowell ,observatory in #aijh4 ,these show that the water vapour bands a and near ,d are stronger in the spectrum of ,mars than in that of the moon at the same altitude4#aja ,the dark markings on ,mars were formerly supposed to represent water and the light parts land4 ,but this idea has now been abandoned4 ,light reflected from a water surface is polarized at certain angles4 ,prof4 ,w4 ,h4 ,pickering1 in his observations on ,mars1 finds no trace of polarization in the light reflected from the dark parts of the planet4 ,but under the same conditions he finds that the bluish-black ring surrounding the white polar cap shows a well-marked polarization of light1 thus indicating that this dark ring is probably water4#ajb ,projections on the limb of the planet have frequently been observed in ,america4 ,these are known not to be mountains1 as they do not reappear under similar conditions4 ,they are supposed to be clouds1 and one seen in ,december1 #aijj1 has been explained as a cloud lying at a height of some #ac miles above the planet's surface and drifting at the rate of about #bg miles an hour4 ,if there are any mountains on ,mars they have not yet been discovered4 ,the existence of the so-called canals of ,mars is supposed to be confirmed by ,lowell's photographs of the planet4 ,but what these canals really represent1 that is the question4 ,they have certainly an artificial look about them1 and they form one of the most curious and interesting problems in the heavens4 ,prof4 ,lowell says-- ,most suggestive of all ,martian phenomena are the canals4 ,were they more generally observable the world would have been spared much scepticism and more theory4 ,they may of course not be artificial1 but observations here ,flagstaff indicate that they are2 as will1 ,i think1 appear from the drawings4 ,for it is one thing to see two or three canals and quite another to have the planet's disc mapped with them on a most elaborate system of triangulation4 ,in the first place they are this season 7,august1 #ahid7 bluish-green1 of the same colour as the seas into which the longer ones all eventually debouch4 ,in the next place they are almost without exception geodetically straight1 supernaturally so1 and this in spite of their leading in every possible direction4 ,then they are of apparently nearly uniform width throughout their length4 ,what they are is another matter4 ,their mere aspect1 however1 is enough to cause all theories about glaciation fissures or surface cracks to die an instant and natural death4#ajc ,some of the observed colour-changes on ,mars are very curious4 ,in ,april1 #aije1 ,mr4 ,lowell observed that the marking known as ,mare ,erythrum1 just above ,syrtis1 had changed from a blue-green to a chocolate-brown colour4 ,the season on ,mars corresponded with our ,february4 ,signor ,v4 ,cerulli says that1 having observed ,mars regularly for ten years1 he has come to the conclusion that the actual existence of the canals is as much a subject for physiological as for astronomical investigation4 ,he states that the phenomena observed are so near the limit of the range of the human eye that in observing them one really experiences an effect accompanying the 'birth of vision4' ,that is to say1 the eye sees more and more as it becomes accustomed1 or strained1 to the delicate markings1 and thus the joining up of spots to form 'canals' and the gemination of the latter follow as a physiological effect1 and need not necessarily be subjective phenomena seen by the unaccustomed eye4#ajd ,the possibility of life on ,mars has been recently much discussed2 some denying1 others asserting4 ,m4 ,e4 ,rogovsky says-- ,as free oxygen and carbonic dioxide may exist in the atmosphere of ,mars1 vegetable and animal life is quite possible4 ,if the temperature which prevails upon ,mars is nearer to -#cf ,c4 than to -#gc ,c41 the existence of living beings like ourselves is possible4 ,in fact1 the ice of some ,greenland and ,alpine glaciers is covered by red alg 7,sphrella nivalis72 we find there also different species of rotaloria1 variegated spiders1 and other animals on the snow fields illuminated by the sun2 at the edges of glacier snows in the ,tyrol we see violet bells of ,soldanella pusilla1 the stalks of which make their way through the snow by producing heat which melts it round about them4 ,finally the ,siberian town ,verkhociansk1 near ,yakutsk1 exists1 though the temperature there falls to -#fih ,c4 and the mean temperature of ,january to -#eab1 and the mean pressure of the vapour of water is less than #jjemm4 ,it is possible1 therefore1 that living beings have become adapted to the conditions now prevailing upon ,mars after the lapse of many ages1 and live at an even lower temperature than upon the earth1 developing the necessary heat themselves4 ,m4 ,rogovsky adds1 ,water in organisms is mainly a liquid or solvent1 and many other liquids may be the same4 ,we have no reason to believe that life is possible only under the same conditions and with the same chemical composition of organisms as upon the earth1 although indeed we cannot affirm that they actually exist on ,mars4#aje ,with the above views the present writer fully concurs4 ,prof4 ,lowell thinks that the polar regions of ,mars1 both north and south1 are actually warmer than the corresponding regions of the earth1 although the mean temperature of the planet is probably twelve degrees lower than the earth's mean temperature4#ajf ,a writer in ,astronomy and ,astrophysics 7#ahib1 p4 #gdh7 says-- ,whether the planet ,mars is inhabited or not seems to be the all-absorbing question with the ordinary reader4 ,with the astronomer this query is almost the last thing about the planet that he would think of when he has an opportunity to study its surface markings 444 no astronomer claims to know whether the planet is inhabited or not4 ,several suggestions have been made with reference to the possibility of signalling to ,mars4 ,but1 as ,mr4 ,larkin of ,mount ,lowe 7,u4,s4,a47 points out1 all writers on this subject seem to forget the fact that the night side of two planets are never turned towards each other4 ,when the sun is between them it is day on the side of ,mars which is towards us1 and also day on the side of the earth which is towards ,mars4 ,when they are on the same side of the sun1 it is day on ,mars when night on the earth1 and for this reason they could never see our signals4 ,this should make it apparent that the task of signalling to ,mars is a more difficult one than the most hopeful theorist has probably considered4 ,all this is under the supposition that the ,martians 7if there are such7 are beings like ourselves4 ,if they are not like us1 we cannot guess what they are like4#ajg ,these views seem to me to be undoubtedly correct1 and show the futility of visual signals4 ,electricity might1 however1 be conceivably used for the purpose2 but even this seems highly improbable4 ,prof4 ,newcomb1 in his work ,astronomy for ,everybody1 says with reference to this question1 ,the reader will excuse me from saying nothing in this chapter about the possible inhabitants of ,mars4 ,he knows just as much about the subject as ,i do1 and that is nothing at all4 ,it is1 however1 quite possible that life in some form may exist on ,mars4 ,as ,lowell well says1 ,life but waits in the wings of existence for its cue to enter the scene the moment the stage is set4#ajh ,with reference to the canals he says-- ,it is certainly no exaggeration to say that they are the most astonishing objects to be viewed in the heavens4 ,there are celestial sights more dazzling1 spectacles that inspire more awe1 but to the thoughtful observer who is privileged to see them well1 there is nothing in the sky so profoundly impressive as these canals of ,mars4#aji ,the eminent ,swedish physicist ,arrhenius thinks that the mean annual temperature on ,mars may possibly be as high as #ej ,f4 ,he says1 ,sometimes the snow-caps on the poles of ,mars disappear entirely during the ,mars summer2 this never happens on our terrestrial poles4 ,the mean temperature of ,mars must therefore be above zero1 probably about #aj ,centigrade #ej ,fahrenheit4 ,organic life may very probably thrive1 therefore1 on ,mars4#aaj ,he thinks that this excess of mean temperature above the calculated temperature may be due to an increased amount of carbonic acid in the planet's atmosphere1 and says any doubling of the percentage of carbon dioxide in the air would raise the temperature of the earth's surface by #d2 and if the carbon dioxide were increased fourfold1 the temperature would rise by #h4aaa ,denning says1--#aab ,a few years ago1 when christening celestial formations was more in fashion than it is now1 a man simply had to use a telescope for an evening or two on ,mars or the moon1 and spice the relation of his seeings with something in the way of novelty1 when his name would be pretty certainly attached to an object and hung in the heavens for all time6 ,a writer in the ,astronomical ,register for ,january1 #ahgi1 humorously suggested that 'the matter should be put into the hands of an advertising agent1' and 'made the means of raising a revenue for astronomical purposes4' ,some men would not object to pay handsomely for the distinction of having their names applied to the seas and continents of ,mars or the craters of the moon4 ,an occultation of ,mars by the moon is recorded by ,aristotle as having occurred on ,april #d1 #ceg ,b4,c4#aac ,seen from ,mars the maximum apparent distance between the earth and moon would vary from #c-a_/b' to nearly #ag'4aad ,,chapter ,,vii ,the ,minor ,planets ,up to #aijh the number of minor planets 7or asteroids7 certainly known amounted to over #fej4 ,from an examination of the distribution of the first #eab of these small bodies1 ,dr4 ,p4 ,stroobant finds that a decided maximum in number occurs between the limits of distance of #bee and #bhe 7earth's mean distance from sun #a71 #aii of the asteroids considered revolving in this annulus4 ,he finds that nearly all the asteroidal matter is concentrated near to the middle of the ring in the neighbourhood of the mean distance of #bg1 and the smallest asteroids are relatively less numerous in the richest zones4#aae ,there are some striking similarities in the orbits of some of the asteroids4 ,thus1 in the small planets ,sophia 7,no4 #bea in order of discovery7 and ,magdalena 7,no4 #cah7 we have the mean distance of ,sophia #caj1 and that of ,magdalena #cai 7earth's mean distance #a74 ,the eccentricities of the orbits are #jji and #jjg2 and the inclinations of the orbits to the plane of the ecliptic #aj #bi' and #aj #cc' respectively4#aaf ,this similarity may be--and probably is--merely accidental1 but it is none the less curious and interesting4 ,some very interesting discoveries have recently been made among the minor planets4 ,the orbit of ,eros intersects the orbit of ,mars2 and the following have nearly the same mean distance from the sun as ,jupiter3-- ,achilles 7#aijf ,,tg71 ,no4 #ehh1 ,patrocles 7#aijf ,,xy71 ,no4 #fag1 ,hector 7#aijg ,,xm71 ,no4 #fbd1 and another 7,no4 #fei7 has been recently found4 ,each of these small planets moves approximately in a vertex of an equilateral triangle that it forms with ,jupiter and the sun4#aag ,the minor planet known provisionally as ,,hn is remarkable for the large eccentricity of its orbit 7#jch71 and its small perihelion distance 7#af74 ,when discovered it had a very high ,south ,declination 7#fa-a_/b71 showing that the inclination of the plane of its orbit to the plane of the ecliptic is considerable4#aah ,dr4 ,bauschinger has made a study of the minor planets discovered up to the end of #aijj4 ,he finds that the ascending nodes of the orbits show a marked tendency to cluster near the ascending node of ,jupiter's orbit1 a fact which agrees well with ,prof4 ,newcomb's theoretical results4 ,there seems to be a slight tendency for large inclinations and great eccentricities to go together2 but there appears to be no connection between the eccentricity and the mean distance from the sun4 ,the longitudes of the perihelia of these small planets show a well-marked maximum near the longitude of ,jupiter's perihelion1 and equally well-marked minimum near the longitude of his aphelion1 which is again in good agreement with ,newcomb's calculations4#aai ,dr4 ,bauschinger's diameter for ,eros is #bj miles4 ,he finds that the whole group1 including those remaining to be discovered1 would probably form a sphere of about #hcj miles in diameter4 ,the total mass of the minor planets has been frequently estimated1 but generally much too high4 ,mr4 ,b4 ,m4 ,roszel of the ,john ,hopkins ,university 7,u4,s4,a47 has made a calculation of the probable mass from the known diameter of ,vesta 7#cai miles1 ,pickering71 and finds the volume of the first #baf asteroids discovered4 ,from this calculation it appears that it would take #caj asteroids of the #fth magnitude1 or #abjj of the #gth to equal the moon in volume4 ,mr4 ,roszel concludes that the probable mass of the whole asteroidal belt is between #a_/ejth and #a_/ajjth of that of the moon4#abj ,subsequently ,mr4 ,roszel extended his study to the mass of #caa asteroids1#aba and found a combined mass of about #a_/djth of the moon's mass4 ,dr4 ,palisa finds that the recently discovered minor planet 7#aije ,,qy7 varies in light to a considerable extent4#abb ,this planet was discovered by ,dr4 ,max ,wolf on ,august #bc1 #aije2 but it was subsequently found that it is identical with one previously known1 7#afg7 ,urda4#abc ,the light variation is said to be from the #aath to the #acth magnitude4#abd ,variation in some of the other minor planets has also been suspected4 ,prof4 ,wendell found a variation of about half a magnitude in the planet ,eunomia 7,no4 #ae74 ,he also found that ,iris 7,no4 #g7 varies about a quarter of a magnitude in a period of about #f;h #abm4#abe ,but these variations are small1 and perhaps doubtful4 ,the variability of ,eros is well known4 ,the planet ,eros is a very interesting one4 ,the perihelion portion of its orbit lies between the orbits of ,mars and the earth1 and the aphelion part is outside the orbit of ,mars4 ,owing to the great variation in its distance from the earth the brightness of ,eros varies from the #fth to the #abth magnitude4 ,that is1 when brightest1 it is #bej times brighter than when it is faintest4#abf ,this variation of light1 is of course1 merely due to the variation of distance2 but some actual variation in the brightness of the planet has been observed4 ,it has been shown by ,oeltzen and ,valz that ,cacciatore's supposed distant comet1 mentioned by ,admiral ,smyth in his ,bedford ,catalogue1 must have been a minor planet4#abg ,dr4 ,max ,wolf discovered #cf new minor planets by photography in the years #ahib-ie4 ,up to the latter year he had never seen one of these through a telescope6 ,his words are1 ,ich selsbt habe noch nie einen meinen kleinen ,planeten am ,himmel gesehen4#abh ,these small bodies have now become so numerous that it is a matter of much difficulty to follow them4 ,at the meeting of the ,royal ,astronomical ,society on ,january #h1 #aiji1 ,mr4 ,g4 ,f4 ,chambers made the following facetious remarks-- ,i would like to make a suggestion that has been in my mind for several years past--that it should be made an offence punishable by fine or imprisonment to discover any more minor planets4 ,they seem to be an intolerable nuisance1 and are a great burden upon the literary gentlemen who have to keep pace with them and record them4 ,i have never seen1 during the last few years at any rate1 any good come from them1 or likely to come1 and ,i should like to see the supply stopped1 and the energies of the ,german gentlemen who find so many turned into more promising channels4 ,among the minor planets numbered #a to #ejj1 about #dj have not been seen since the year of their discovery1 and must be regarded as lost4#abi ,,chapter ,,viii ,jupiter ,this brilliant planet--only inferior to ,venus in brightness--was often seen by ,bond 7,jun47 with the naked eye in high and clear sunshine2 also by ,denning1 who has very keen eyesight4 ,its brightness on such occasions is so great1 that--like ,venus--it casts a distinct shadow in a dark room4#acj ,the great red spot on ,jupiter seems to have been originally discovered by ,robert ,hooke on ,may #i1 #affd1 with a telescope of #b inches aperture and #ab feet focus4 ,it seems to have existed ever since2 at least the evidence is1 according to ,denning1 in favour of the identity of ,hooke's spot with the red spot visible in recent years4 ,the spot was also observed by ,cassini in the years #affe-gb1 and is sometimes called ,cassini's spot4 ,but the real discoverer was ,hooke4#aca ,the orbit of ,jupiter is so far outside the earth's orbit that there can be little visible in the way of phase--as in the case of ,mars1 where the gibbous phase is sometimes very perceptible4 ,some books on astronomy state that ,jupiter shows no phase4 ,but this is incorrect4 ,a distinct1 although very slight1 gibbous appearance is visible when the planet is near quadrature4 ,webb thought it more conspicuous in twilight than in a dark sky4 ,with large telescopes1 ,jupiter's satellites ,,ii4 and ,,iii4 have been seen--in consequence of ,jupiter's phase--to emerge from occultation at a sensible distance from the limb4#acb ,according to ,m4 ,e4 ,rogovsky1 the high albedo of ,jupiter1 the appearance of the clear 7red7 and dark spots on its surface and their continual variation1 the different velocity of rotation of the equatorial and other zones of its surface1 and particularly its small density 7#acc1 water as unity71 all these facts afford irrefragable proofs of the high temperature of this planet4 ,the dense and opaque atmosphere hides its glowing surface from our view1 and we see therefore only the external surface of its clouds4 ,the objective existence of this atmosphere is proved by the bands and lines of absorption in its spectrum4 ,the interesting photograph obtained by ,draper1 ,september #bg1 #ahgi1 in which the blue and green parts are more brilliant for the equatorial zone than for the adjacent parts of the surface1 appears to show that ,jupiter emits its proper light4 ,it is possible that the constant red spot noticed on its surface by several observers1 as ,gledhill1 ,lord ,rosse1 and ,copeland 7#ahgc71 ,russel and ,bredikhin 7#ahgf71 is the summit of a high glowing mountain4 ,g4 ,w4 ,hough considers ,jupiter to be gaseous1 and ,a4 ,ritter inferred from his formul that in this case the temperature at the centre would be #fjj1jjj ,c4#acc ,the four brighter satellites of ,jupiter are usually known by numbers ,i41 ,,ii41 ,,iii41 and ,,iv42 ,i4 being the nearest to the planet1 and ,,iv4 the farthest4 ,,iii4 is usually the brightest1 and ,,iv4 the faintest1 but exceptions to this rule have been noticed4 ,with reference to the recently discovered sixth and seventh satellites of ,jupiter1 ,prof4 ,perrine has suggested that the large inclination of their orbits to the plane of the planet's equator seems to indicate that neither of these bodies was originally a member of ,jupiter's family1 but has been captured by the planet4 ,this seems possible as the orbits of some of the minor planets lie near the orbit of ,jupiter 7see ,minor ,planets74 ,a similar suggestion has been made by ,prof4 del ,marmol4#acd ,many curious observations have been recorded with reference to ,jupiter's satellites2 some very difficult of explanation4 ,in #agaa ,bianchini saw satellite ,,iv4 so faint for more than an hour that it was hardly visible6 ,a similar observation was made by ,lassell with a more powerful telescope on ,june #ac1 #ahdi4 ,key1 ,t4 ,t4 ,smyth1 and ,denning have also recorded unusual faintness4#ace ,a very remarkable phenomenon was seen by ,admiral ,smyth1 ,maclear1 and ,pearson on ,june #bf1 #ahbh4 ,satellite ,,ii41 having fairly entered on ,jupiter1 was found #ab or #ac minutes afterwards outside the limb1 where it remained visible for at least #d minutes1 and then suddenly vanished4 ,as ,webb says1 ,explanation is here set at defiance2 demonstrably neither in the atmosphere of the earth1 nor ,jupiter1 where and what could have been the cause8 ,at present we can get no answer4#acf ,when ,jupiter is in opposition to the sun--that is1 on the meridian at midnight--satellite ,i4 has been seen projected on its own shadow1 the shadow appearing as a dark ring round the satellite4 ,on ,january #bh1 #ahdh1 at ,cambridge 7,u4,s4,a47 satellite ,,iii4 was seen in transit lying between the shadows of ,i4 and ,,ii4 and so black that it could not be distinguished from the shadows1 except by the place it occupied4 ,this seems to suggest inherent light in the planet's surface1 as the satellite was at the time illuminated by full sunshine2 its apparent blackness being due to the effect of contrast4 ,cassini on one occasion failed to find the shadow of satellite ,i4 when it should have been on the planet's disc1#acg an observation which again points to the glowing light of ,jupiter's surface4 ,sadler and ,trouvelot saw the shadow of satellite ,i4 double6 an observation difficult to explain--but the same phenomenon was again seen on the evening of ,september #ai1 #ahia1 by ,mr4 ,h4 ,s4 ,halbert of ,detroit1 ,michigan 7,u4,s4,a474 ,he says that the satellite was in transit nearing egress1 and it appeared as a white disc against the dark southern equatorial belt2 following it was the usual shadow1 and at an equal distance from this was a second shadow1 smaller and not so dark as the true one1 and surrounded by a faint penumbra4#ach ,a dark transit of satellite ,,iii4 was again seen on the evening of ,december #ai1 #ahia1 by two observers in ,america4 ,one observer noted that the satellite1 when on the disc of the planet1 was intensely black4 ,to the other observer 7,willis ,l4 ,barnes7 it appeared as an ill-defined dark image4#aci ,a similar observation was made on ,october #i of the same year by ,messrs4 ,gale and ,innes4#adj ,a black transit of satellite ,,iv4 was seen by several observers in #ahgc1 and by ,prof4 ,barnard on ,may #d1 #ahhf4 ,the same phenomenon was observed on ,october #cj1 #aijc1 in ,america1 by ,miss ,anne ,s4 ,young and ,willis ,s4 ,barnes4 ,miss ,young says-- ,the ingress of the satellite took place at #h;h #ejm 7,e4 standard time7 when it became invisible upon the background of the planet4 ,an hour later it was plainly visible as a dark round spot upon the planet4 ,it was decidedly darker than the equatorial belt4#ada ,the rather rare phenomenon of an occultation of one of ,jupiter's satellites by another was observed by ,mr4 ,apple1 director of the ,daniel ,scholl ,observatory1 ,franklin and ,marshall ,college1 ,lancaster1 ,pa4 7,u4,s4,a471 on the evening of ,march #af1 #aijh4 ,the satellites in question were ,i4 and ,,ii41 and they were so close that they could not be separated with the #aae-;inch telescope of the ,observatory4#adb ,one of the present writer's first observations with a telescope is dated ,may #ag1 #ahgc1 and is as follows3 ,observed one of ,jupiter's satellites occulted 7or very nearly so7 by another4 ,appeared as one with power #acc 7on #c-;inch refractor in the ,punjab74 ,these satellites were probably ,i4 and ,,ii4 ,jupiter has been seen on several occasions apparently without his satellites2 some being behind the disc1 some eclipsed in his shadow1 and some in transit across the disc4 ,this phenomenon was seen by ,galileo1 ,march #ae1 #afaa2 by ,molyneux1 on ,november #ab1 #afha2 by ,sir ,william ,herschel1 ,may #bc1 #ahjb2 by ,wallis1 ,april #ae1 #ahbf2 by ,greisbach1 ,september #bg1 #ahdc2 and by several observers on four occasions in the years #ahfg-ahie4adc ,the phenomenon again occurred on ,october #c1 #aijg1 ,no4 #a being eclipsed and occulted1 ,no4 #b in transit1 ,no4 #c eclipsed1 and ,no4 #d occulted4#add ,it was not1 however1 visible in ,europe1 but could have been seen in ,asia and ,oceania4#add ,the phenomenon will occur again on ,october #bb1 #aiac4ade ,on the night of ,september #ai1 #aijc1 a star of magnitude #f-a_/b was occulted by the disc of ,jupiter4 ,this curious and rare phenomenon was photographed by ,m4 ,lucien ,rudaux at the ,observatory of ,donville1 ,france4#adf ,the star was ,lalande #defih 7 ,,bac #habi74adg ,prof4 ,barnard1 using telescopes with apertures from #e inches up to #cf inches 7,lick71 has failed to see a satellite through the planet's limb 7an observation which has been claimed by other astronomers74 ,he says1 ,to my mind this has been due to either poor seeing1 a poor telescope1 or an excited observer4#adh ,he adds-- ,i think it is high time that the astronomers reject the idea that the satellites of ,jupiter can be seen through his limb at occultation4 ,when the seeing is bad there is a spurious limb to ,jupiter that well might give the appearance of transparency at the occultation of a satellite4 ,but under first-class conditions the limb of ,jupiter is perfectly opaque4 ,it is quibbling and begging the question altogether to say the phenomenon of transparency may be a rare one and so have escaped my observations4 ,has any one said that the moon was transparent when a star has been seen projected on it when it ought to have been behind it8 ,prof4 ,barnard and ,mr4 ,douglass have seen white polar caps on the third and fourth satellites of ,jupiter4 ,the former says they are exactly like those on ,mars4 ,both caps of the fourth satellite have been clearly distinguished1 that at the north being sometimes exceptionally large1 covering a surface equal to one-quarter or one-third of the diameter of the satellite4#adi ,this was confirmed on ,november #bc1 #aijf1 when ,signor ,j4 ,comas ,sola observed a brilliant white spot surrounded by a dark marking in the north polar region of the third satellite4 ,there were other dark markings visible1 and the satellite presented the appearance of a miniature of ,mars4#aej ,an eighth satellite of ,jupiter has recently been discovered by ,mr4 ,melotte at the ,greenwich ,observatory by means of photography4 ,it moves in a retrograde direction round ,jupiter in an orbit inclined about #cj to that of the planet4 ,the period of revolution is about two years4 ,the orbit is very eccentric1 the eccentricity being about one-third1 or greater than that of any other satellite of the solar system4 ,when nearest to ,jupiter it is about #i millions of miles from the planet1 and when farthest about #bj millions4#aea ,it has been suggested by ,mr4 ,george ,forbes that this satellite may possibly be identical with the lost comet of ,lexell which at its return in the year #aggi became entangled in ,jupiter's system1 and has not been seen since4 ,if this be the case1 we should have the curious phenomenon of a comet revolving round a planet6 ,according to ,humboldt the four bright satellites of ,jupiter were seen almost simultaneously and quite independently by ,simon ,marius at ,ausbach on ,december #bi1 #afji1 and by ,galileo at ,padua on ,january #g1 #afaj4aeb ,the actual priority1 therefore1 seems to rest with ,simon ,marius1 but the publication of the discovery was first made by ,galileo in his ,nuncius ,siderius 7#afaj74aec ,grant1 however1 in his ,history of ,physical ,astronomy1 calls ,simon ,marius an impudent pretender6 7p4 #gi74 ,m4 ,dupret at ,algiers saw ,jupiter with the naked eye on ,september #bf1 #ahij1 twenty minutes before sunset4#aed ,humboldt states that he saw ,jupiter with the naked eye when the sun was from #ah to #bj above the horizon4#aee ,this was in the plains of ,south ,america near the sea-level4 ,,chapter ,,ix ,saturn ,to show the advantages of large telescopes over small ones1 ,mr4 ,c4 ,roberts says that with the #be-;inch refractor of the ,cambridge ,observatory the view of the planet ,saturn is indescribably glorious2 everything ,i had ever seen before was visible at a glance1 and an enormous amount of detail that ,i had never even glimpsed before1 after a few minutes' observation4#aef ,chacornac found that the illumination of ,saturn's disc is the reverse of that of ,jupiter1 the edges of ,saturn being brighter than the centre of the disc1 while in the case of ,jupiter--as in that of the sun--the edges are fainter than the centre4#aeg ,according to ,mr4 ,denning1 ,saturn bears satisfactorily greater magnifying power than either ,mars or ,jupiter4#aeh ,at an occultation of ,saturn by the moon1 which occurred on ,june #ac1 #aijj1 ,m4 ,m4 ,honorat noticed the great contrast between the slightly yellowish colour of the moon and the greenish tint of the planet4#aei ,in the year #ahib1 when the rings of ,saturn had nearly disappeared1 ,prof4 ,l4 ,w4 ,underwood1 of the ,underwood ,observatory1 ,appleton1 ,wisconsin 7,u4,s4,a471 saw one of ,saturn's satellites 7,titan7 apparently moving along the needlelike appendage to the planet presented by the rings4 ,the apparent diameter of the satellite so far exceeded the apparent thickness of the ring that it gave the appearance of a beautiful golden bead moving very slowly along a fine golden thread4#afj ,in #aijg1 when the rings of ,saturn became invisible in ordinary telescopes1 ,professor ,campbell1 observing with the great ,lick telescope1 noticed prominent bright knots1 visible 444 in ,saturn's rings4 ,the knots were symmetrically placed1 two being to the east and two to the west4 ,this was confirmed by ,mr4 ,lowell1 who says1 ,condensations in ,saturn's rings confirmed here and measured repeatedly4 ,symmetric and permanent4 ,this phenomenon was previously seen by ,bond in the years #ahdg-ef4 ,measures of these light spots made by ,prof4 ,barnard with the #dj-;inch ,yerkes telescope show that the outer one corresponded in position with the outer edge of the middle ring close to the ,cassini division1 and the inner condensation1 curious to say1 seemed to coincide in position with the crape ring4 ,prof4 ,barnard thinks that the thickness of the rings must be greatly under #ajj miles1 and probably less than #ej miles1 and he says-- ,the important fact clearly brought out at this apparition of ,saturn is that the bright rings are not opaque to the light of the sun--and this is really what we should expect from the nature of their constitution as shown by the theory of ,clerk ,maxwell1 and the spectroscopic results of ,keeler4#afa ,under certain conditions it would be theoretically possible1 according to ,mr4 ,whitmell1 to see the globe of ,saturn through the ,cassini division in the ring4 ,but the observation would be one of great difficulty and delicacy4 ,the effect would be that1 of the arc of the division which crosses the planet's disc1 a small portion will appear bright instead of dark1 and may almost disappear4#afb ,a remarkable white spot was seen on ,saturn on ,june #bc1 #aijc1 by ,prof4 ,barnard1 and afterwards by ,mr4 ,denning4#afc ,another white spot was seen by ,denning on ,july #i of the same year4#afd ,from numerous observations of these spots1 ,denning found a rotation period for the planet of about #aj;h #cim #bas4#afe ,from observations of the same spots ,signor ,comas ,sola found a period #aj;h #chm#d1 a close agreement with ,denning's result4 ,for ,saturn's equator1 ,prof4 ,hill found a rotation period of #aj;h #adm #bcs#h1 so that--as in the case of ,jupiter--the rotation is faster at the equator than in the northern latitudes of the planet4 ,a similar phenomenon is observed in the sun4 ,mr4 ,denning's results were fully confirmed by ,herr ,leo ,brenner1 and other ,german astronomers4#aff ,photographs taken by ,prof4 ,v4 ,m4 ,slipher in ,america show that the spectrum of ,saturn is similar to that of ,jupiter4 ,none of the bands observed in the planet's spectrum are visible in the spectrum of the rings4 ,this shows that if the rings possess an atmosphere at all1 it must be much rarer than that surrounding the ball of the planet4 ,prof4 ,slipher says that none of the absorption bands in the spectrum of ,saturn can be identified with those bands due to absorption in the earth's atmosphere1 and there is no trace of aqueous vapour4#afg ,in ,september1 #aijg1 ,m4 ,g4 ,fournier suspected the existence of a faint transparent and luminous ring outside the principal rings of ,saturn4 ,he thinks that it may possibly be subject to periodical fluctuations of brightness1 sometimes being visible and sometimes not4#afh ,this dusky ring was again suspected at the ,geneva ,observatory in ,october1 #aijh4afi ,m4 ,schaer found it a difficult object with a #af-;inch ,cassegrain reflector4 ,prof4 ,stromgen at ,copenhagen1 and ,prof4 ,hartwig at ,bamberg1 however1 failed to see any trace of the supposed ring4#agj ,it was seen at ,greenwich in ,october1 #aijh4 ,a dark transit of ,saturn's satellite ,titan across the disc of the planet has been observed on several occasions4 ,it was seen by ,mr4 ,isaac ,w4 ,ward1 of ,belfast1 on ,march #bg1 #ahib1 with a #dc-;inch ,wray refractor4 ,the satellite appeared smaller than its shadow4 ,the phenomenon was also seen on ,march #ab of the same year by the ,rev4 ,a4 ,freeman1 ,mr4 ,mee1 and ,m4 ,f4 ,terby2 and again on ,november #f1 #aijg1 by ,mr4 ,paul ,chauleur and ,mr4 ,a4 ,b4 ,cobham4#aga ,the recently discovered tenth satellite of ,saturn1 ,themis1 was discovered by photography1 and has never been seen by the eye even with the largest telescopes6 ,but its existence is beyond all doubt1 and its orbit round the planet has been calculated4 ,prof4 ,hussey of the ,lick ,observatory finds that ,saturn's satellite ,mimas is probably larger than ,hyperion4 ,he also finds from careful measurements that the diameter of ,titan is certainly overestimated1 and that its probable diameter is about #bejj miles4#agb ,the ,french astronomer1 ,m4 ,lucien ,rudaux1 finds the following variation in the light of the satellites of ,saturn3-- ,japetus from #ith magnitude to #abth ,rhea #i #ajf ,dione #ie #aje ,tethys #ih #aje ,titan #h #hf ,the variation of light is1 he thinks1 due to the fact that the period of rotation of each satellite is equal to that of their revolution round the planet2 as in the case of our moon4#agc ,the names of the satellites of ,saturn are derived from the ancient heathen mythology4 ,they are given in order of distance from the planet1 the nearest being ,mimas and the farthest ,themis4 #a4 ,mimas was a ,trojan born at the same time as ,paris4 #b4 ,enceladus was son of ,tartarus and ,ge4 #c4 ,tethys was wife of ,oceanus1 god of ocean currents4 ,she became mother of all the chief rivers in the universe1 as also the ,oceanides or sea nymphs4 #d4 ,dione was one of the wives of ,zeus4 #e4 ,rhea was a daughter of ,uranus4 ,she married ,saturn1 and became the mother of ,vesta1 ,ceres1 ,juno1 and ,pluto4 #f4 ,titan was the eldest son of ,uranus4 #g4 ,hyperion was the god of day1 and the father of sun and moon4 #h4 ,japetus was the fifth son of ,uranus1 and father of ,atlas and ,prometheus4#agd #i4 ,phoebe was daughter of ,uranus and ,ge4 #aj4 ,themis was daughter of ,uranus and ,ge1 and1 therefore1 sister of ,phoebe4 ,in a review of ,prof4 ,comstock's ,text ,book of ,astronomy in ,the ,observatory1 ,november1 #aija1 the remark occurs1 ,we are astonished to see that ,mr4 ,comstock alludes with apparent seriousness to the nine satellites of ,saturn4 ,as regards the ninth satellite1 we thought that all astronomers held with ,mrs4 ,betsy ,prig on the subject of this astronomical ,mrs4 ,harris4 ,this reads curiously now 7#aiji7 when the existence of the ninth satellite 7,phoebe7 has been fully confirmed1 and a tenth satellite discovered4 ,,chapter ,x ,uranus and ,neptune ,from observations of ,uranus made in #ahif1 ,m4 ,leo ,brenner concluded that the planet rotates on its axis in about #h-a_/b hours 7probably #h;h #bgm74 ,this is a short period1 but considering the short periods of ,jupiter and ,saturn there seems to be nothing improbable about it4 ,prof4 ,barnard finds that the two inner satellites of ,uranus are difficult objects even with the great #cf-;inch telescope of the ,lick ,observatory6 ,they have1 however1 been photographed at ,cambridge 7,u4,s4,a47 with a #ac-;inch lens1 although they are among the most difficult objects known4#age ,sir ,william ,huggins in #ahga found strong absorption lines 7six strong lines7 in the spectrum of ,uranus4 ,one of these lines indicated the presence of hydrogen1 a gas which does not exist in our atmosphere4 ,three of the other lines seen were situated near lines in the spectrum of atmospheric air4 ,neither carbonic acid nor sodium showed any indications of their presence in the planet's spectrum4 ,a photograph by ,prof4 ,slipher of ,neptune's spectrum shows the spectrum of this planet to contain many strong absorption bands4 ,these bands are so pronounced in the part of the spectrum between the ,fraunhofer lines ,f and ,d1 as to leave the solar spectrum unrecognizable4444 ,neptune's spectrum is strikingly different from that of ,uranus1 the bands in the latter planet all being reinforced in ,neptune4 ,in this planet there are also new bands which have not been observed in any of the other planets4 ,the ,f line of hydrogen is remarkably dark 444 this band is of more than solar strength in the spectrum of ,uranus also4 ,thus free hydrogen seems to be present in the atmosphere of both these planets4 ,this and the other dark bands in these planets bear evidence of an enveloping atmosphere of gases which is quite unlike that which surrounds the earth4#agf ,with the #ah-;inch equatorial telescope of the ,strasburgh ,observatory1 ,m4 ,wirtz measured the diameter of ,neptune1 and found from forty-nine measures made between ,december #i1 #aijb1 and ,march #bh1 #aijc1 a value of #bcjc at a distance of #cjajic 7earth's distance from sun #a74 ,this gives a diameter of #ej1bea kilometres1 or about #ca1bbe miles1#agg and a mean density of #aed 7water #a2 earth's mean density #eec74 ,prof4 ,barnard's measures gave a diameter of #cb1ijj miles1 a fairly close agreement1 considering the difficulty of measuring so small a disc as that shown by ,neptune4 ,the satellite of ,neptune was photographed at the ,pulkown ,observatory in the year #ahii4 ,the name ,triton has been suggested for it4 ,in the old ,greek mythology ,triton was a son of ,neptune1 so the name would be an appropriate one4 ,the existence of a second satellite of ,neptune is suspected by ,prof4 ,schaeberle1 who thinks he once saw it with the #cf-;inch telescope of the ,lick ,observatory on an exceptionally fine night in #ahie4agh ,but this supposed discovery has not yet been confirmed4 ,lassell also thought he had discovered a second satellite1 but this supposed discovery was never confirmed4#agh ,the ancient ,burmese mention eight planets1 the sun1 the moon1 ,mercury1 ,venus1 ,mars1 ,jupiter1 ,saturn1 and another named ,rhu1 which is invisible4 ,it has been surmised that ,rhu is ,uranus1 which is just visible to the naked eye1 and may possibly have been discovered by keen eyesight in ancient times4 ,the present writer has seen it several times without optical aid in the ,west of ,ireland1 and with a binocular field-glass of #b inches aperture he found it quite a conspicuous object4 ,when ,neptune was visually discovered by ,galle1 at ,berlin1 he was assisted in his observation by ,prof4 d',arrest4 ,the incident is thus described by ,dr4 ,dreyer1 ,on the night of ,june #ad1 #ahgd1 while observing ,coggia's comet together1 ,i reminded ,prof4 d',arrest how he had once said in the course of a lecture1 that he had been present at the finding of ,neptune1 and that 'he might say it would not have been found without him4' ,he then told me 7and ,i wrote it down the next day71 how he had suggested the use of ,bremiker's map 7as first mentioned by ,dr4 ,galle in #ahgg7 and continued1 ',we then went back to the dome1 where there was a kind of desk1 at which ,i placed myself with the map1 while ,galle1 looking through the refractor1 described the configurations of the stars he saw4 ,i followed them on the map one by one1 until he said3 ,and then there is a star of the #hth magnitude1 in such and such a position1 whereupon ,i immediately exclaimed3 ,that star is not on the map4'#agi ,this was the planet4 ,but it seems to the present writer that if ,galle or d',arrest had access to ,harding's ,atlas 7as they probably had7 they might easily have found the planet with a good binocular field-glass4 ,as a matter of fact ,neptune is shown in ,harding's ,atlas 7#ahbb7 as a star of the #hth magnitude1 having been mistaken for a star by ,lalande on ,may #h and #aj1 #agie2 and the present writer has found ,harding's #hth magnitude stars quite easy objects with a binocular field-glass having object-glasses of two inches diameter1 and a power of about six diameters4 ,,supposed ,,planet ,,beyond ,,neptune4--,the possible existence of a planet beyond ,neptune has been frequently suggested4 ,from considerations on the aphelia of certain comets1 ,prof4 ,forbes in #ahhj computed the probable position of such a body4 ,he thought this hypothetical planet would be considerably larger than ,jupiter1 and probably revolve round the sun at a distance of about #ajj times the earth's mean distance from the sun4 ,the place indicated was between ,r4,a4 #aa;h #bdm and #ab;h #abm1 and declination #j #j' to #f #j' north4 ,with a view to its discovery1 the late ,dr4 ,roberts took a series of eighteen photographs covering the region indicated4 ,the result of an examination of these photographs showed1 ,dr4 ,roberts says1 that no planet of greater brightness than a star of the #aeth magnitude exists on the sky area herein indicated4 ,prof4 ,w4 ,h4 ,pickering has recently revived the question1 and has arrived at the following results3 ,mean distance of the planet from the sun1 #eai 7earth's mean distance #a72 period of revolution1 #cgc-a_/b years2 mass about twice the earth's mass2 probable position for #aiji about ,r4,a4 #g;h #dgm1 north declination #ba1 or about #e south-east of the star ,greek3 k ,geminorum4 ,the supposed planet would be faint1 its brightness being from #aa-a_/b to #ac-a_/b1 according to the albedo 7or reflecting power7 it may have4#ahj ,prof4 ,forbes has again attacked the question of a possible ultra-,neptunian planet1 and from a consideration of the comets of #aeef1 #ahdc ,i1 #ahhj ,i1 and #ahhb ,,ii1 finds a mean distance of #ajed1 with an inclination of the orbit of #eb to the plane of the ecliptic4 ,this high inclination implies that during the greatest part of its revolution it is beyond the zodiac1 and this1 ,mr4 ,w4 ,t4 ,lynn thinks1 may partly account for its not having hitherto been found by observation4#aha ,from a consideration of the approximately circular shape of the orbits of all the large planets of the solar system1 ,dr4 ,see suggests the existence of three planets outside ,neptune1 with approximate distances from the sun of #db1 #ef1 and #gb respectively 7earth's distance #a71 and recommends a photographic search for them4 ,he says1 ,to suppose the planetary system to terminate with an orbit so round as that of ,neptune is as absurd as to suppose that ,jupiter's system terminates with the orbit of the fourth satellite4#ahb ,according to ,grant1 even twenty years before the discovery of ,neptune the error of ,prof4 ,adams' first approximation amounted to little more than #aj4ahc ,,chapter ,,xi ,comets ,we learn from ,pliny that comets were classified in ancient times1 according to their peculiar forms1 into twelve classes1 of which the principal were3 ,pogonias1 bearded2 ,lampadias1 torch-like2 ,xiphias1 sword-like2 ,pitheus1 tun-like2 ,acontias1 javelin-like2 ,ceratias1 horn-like2 ,disceus1 quoit-like2 and ,hippias1 horse-mane-like4#ahd ,of the numerous comets mentioned in astronomical records1 comparatively few have been visible to the naked eye4 ,before the invention of the telescope 7#afaj7 only those which were so visible could1 of course1 be recorded4 ,these number about #djj4 ,of the #djj observed since then1 some #gj or #hj only have been visible by unaided vision2 and most of these now recorded could never have been seen without a telescope4 ,during the last century1 out of #cjj comets discovered1 only #ac were very visible to the naked eye4 ,hence1 when we read in the newspapers that a comet has been discovered the chances are greatly against it becoming visible to the naked eye4#ahe ,although comparatively few comets can be seen without a telescope1 they are sometimes bright enough to be visible in daylight6 ,such were those of ,b4,c4 #dc1 ,a4,d4 #aajf1 #adjb1 #aecb1 #aegg1 #agdd1 #ahdc1 and the great ,september comet of #ahhb4 ,if we except the great comet of #ahfa1 through the tail of which the earth is supposed to have passed1 the comet which came nearest to the earth was that of #aggj1 known as ,lexell's1 which approached us within two millions of miles1 moving nearly in the plane of the ecliptic4 ,it produced1 however1 no effect on the tides1 nor on the moon's motion1 which shows that its mass must have been very small4 ,it was computed by ,laplace that if its mass had equalled that of the earth1 the length of our year would have been shortened by #b hours #dg minutes1 and as there was no perceptible change ,laplace concluded that the comet's mass did not exceed #a_/ejjjth of the earth's mass4 ,this is the comet which passed so near to ,jupiter that its period was reduced to #e-a_/b years4 ,owing to another near approach in #aggi it became invisible from the earth1 and is now lost4#ahf ,its identity with the recently discovered eighth satellite of ,jupiter has been suggested by ,mr4 ,george ,forbes 7see under ,jupiter74 ,at the near approach of ,lexell's comet to the earth in #aggj1 ,messier1 the comet ferret1 found that its head had an apparent diameter of #b-a_/b1 or nearly five times that of the moon6 ,another case of near approach to the earth was that of ,biela's comet at its appearance in #ahje4 ,on the evening of ,december #i of that year1 the comet approached the earth within #c1chj1jjj miles4#ahg ,the comet of ,a4,d4 #aajf is stated to have been seen in daylight close to the sun4 ,this was on ,february #d of that year4 ,on ,february #aj it had a tail of #fj in length1 according to ,gaubil4#ahh ,the comet of #aegg seems to have been one of the brightest on record4 ,according to ,tycho ,brah1 it was visible in broad daylight4 ,he describes the head as round1 bright1 and of a yellowish light1 with a curved tail of a reddish colour4#ahi ,the comet of #afeb was observed for about three weeks only1 and ,hevelius and ,comiers state that it was equal to the moon in apparent size6 ,this would indicate a near approach to the earth4 ,an orbit computed by ,halley shows that the least distance was about #ab millions of miles1 and the diameter of the comet's head rather less than #aaj1jjj miles1 or about #ad times the earth's diameter4 ,according to ,mr4 ,denning1 most of the periodical comets at perihelion are outside the earth's orbit1 and hence it follows that they escape observation unless the earth is on the same side of the sun as the comet4#aij ,it was computed by ,m4 ,faye that the volume of the famous ,donati's comet 7#aheh7 was about #ejj times that of the sun6 ,on the other hand1 he calculated that its mass 7or quantity of matter it contained7 was only a fraction of the earth's mass4 ,this shows how almost inconceivably tenuous the material forming the comet must have been--much more rarefied1 indeed1 than the most perfect vacuum which can be produced in an air-pump4 ,this tenuity is shown by the fact that stars were seen through the tail as if the tail did not exist4 ,a mist of a few hundred yards in thickness is sufficient to hide the stars from our view1 while a thickness of thousands of miles of cometary matter does not suffice even to dim their brilliancy6 ,at the time of the appearance of the great comet of #ahdc1 it was doubtful whether the comet had transited the sun's disc4 ,but it is now known1 from careful calculations by ,prof4 ,hubbard1 that a transit really took place between #aa;h #bhm and #ab;h #bim on ,february #bg1 #ahdc1 and might have been observed in the southern hemisphere4 ,the distance of this remarkable comet from the sun at its perihelion passage was less than that of any known comet4 ,a little before #aj p4m4 on ,february #bg1 the comet passed within #ha1ejj miles of the sun's surface with the enormous velocity of #cdh miles a second6 ,it remained less than #b-a_/d hours north of the ecliptic1 passing from the ascending to the descending node of its orbit in #b;h #acm#d4aia ,the great comet of #ahhb transited the sun's disc on ,sunday1 ,september #ag1 of that year1 the ingress taking place at #d;h #ejm #ehs1 ,cape mean time4 ,when on the sun the comet was absolutely invisible1 showing that there was nothing solid about it4 ,it was visible near the sun with the naked eye a little before the transit took place4#aib ,this great comet was found by several computors to have been travelling in an elliptic orbit with a period of about eight centuries4 ,morrison found #gab years2 ,frisby1 #gid2 ,fabritius1 #hbc2 and ,kreutz1 #hdc years4#aic ,the great southern comet of #ahhg may be described as a comet without a head6 ,the popular idea of a comet is a star with a tail4 ,but in this case there was no head visible--to the naked eye at least4 ,dr4 ,thome of the ,cordoba ,observatory--its discoverer--describes it as a beautiful object--a narrow1 straight1 sharply defined1 graceful tail1 over #dj long1 shining with a soft starry light against a dark sky1 beginning apparently without a head1 and gradually widening and fading as it extended upwards4#aid ,the great southern comet of #aija had five tails on ,may #f of that year4 ,two were fairly bright1 and the remaining three rather faint4 ,mr4 ,gale saw a number of faint stars through the tails4 ,the light of these seem to have been undimmed4 ,mr4 ,cobham noticed that the stars ,rigel and ,greek3 b ,eridani shone through one of the faint tails1 and showed no perceptible difference4#aie ,prof4 ,w4 ,h4 ,pickering says that the head of a comet1 as far as our present knowledge is concerned1 seems therefore to be merely a meteor swarm containing so much gaseous material that when electrified by its approach to the sun it will be rendered luminous 7,harvard ,annual1 vol4 xxxii4 part ii4 p4 #bie7 444 if the meteors and their atmospheres are sufficiently widely separated from one another1 the comet may be brilliant and yet transparent at the same time4 ,in the case of ,swift's comet of #ahib some periodical differences of appearance were due1 according to ,prof4 ,w4 ,h4 ,pickering1 to a rotation of the comet round an axis passing longitudinally through the tail1 and he estimated the period of rotation at about #id to #ig hours4 ,he computed that in this comet the repulsive force exerted by the sun on the comet's tail was about #cie times the gravitational force4#aif ,the comet known as #aijb;b approached the planet ,mercury within two millions of miles on ,november #bi of that year4 ,prof4 ,o4 ,c4 ,wendell1 of ,harvard ,observatory1 made some observations on the transparency of this comet4 ,he found with the aid of a photometer and the #ae-;inch telescope of the observatory that in the case of two faint stars over which the comet passed on ,october #ad1 #aijb1 the absorption of light by the comet was insensible1 and possibly did not exceed one or two hundredths of a magnitude1#aig an amount quite imperceptible to the naked eye1 and shows conclusively how almost inconceivably rarefied the substance of this comet must be4 ,the comet known as ,morehouse 7#aijh;c7 showed some curious and wonderful changes4 ,mr4 ,borelly found that five tails are visible on a photographic plate taken on ,october #c1 #aijh1 and the trail of an occulted star indicates a slight absorption effect4 ,according to ,m4 ,l4 ,rabourdin1 great changes took place from day to day1 and even during the course of an hour6 ,similar changes were recorded by ,g4 ,m4 ,gauthier2 and ,prof4 ,barnard1 who photographed the comet on #cj nights from ,september #b to ,october #ac1 states that the photographs of ,september #cj are unique1 whilst the transformation which took place between the taking of these and the taking of the next one on ,october #a was very wonderful4#aih ,the spectrum showed the lines of cyanogen instead of the hydrocarbon spectrum shown by most comets4 ,prof4 ,barnard has suggested that all the phenomena of comets' tails cannot be explained by a repulsive force from the sun4 ,short tails issuing from the comet's nucleus at considerable angles with the main tail point to eruptive action in the comet itself4 ,the rapid changes and distortions frequently observed in the tails of some comets suggest motion through a resisting medium2 and the sudden increase of light also occasionally observed points in the same direction4#aii ,it was computed by ,olbers that if a comet having a mass of #a_/bjjjth of the earth's mass--which would form a globe of about #ebj miles in diameter and of the density of granite--collided with the earth1 with a velocity of #dj miles a second1 our globe would be shattered into fragments4#bjj ,but that any comet has a solid nucleus of this size seems very doubtful2 and we may further say that the collision of the earth with any comet is highly improbable4 ,it seems to be a common idea that harvests are affected by comets1 and even comet wines are sometimes spoken of4 ,but we know that the earth receives practically no heat from the brightest comet4 ,even in the case of the brilliant comet of #ahaa1 one of the finest on record1 it was found that all the efforts to concentrate its rays did not produce the slightest effect on the blackened bulb of the most sensitive thermometer4 ,arago found that the year #ahjh1 in which several comets were visible1 was a cold year1 and #ahca1 in which there was no comet1 enjoyed a much higher temperature than #ahai1 when there were three comets1 one of which was very brilliant4#bja ,we may1 therefore1 safely conclude that even a large comet has no effect whatever on the weather4 ,from calculations on the orbit of ,halley's comet1 the next return of which is due in #aiaj1 ,messrs4 ,cowell and ,crommelin find that the identity of the comet shown on the ,bayeux ,tapestry with ,halley's comet is now fully established4 ,they find that the date of perihelion passage was ,march #be1 #ajff1 which differs by only #d days from the date found by ,hind4 ,the imposing aspect of the comet in #ajff described in ,european chronicles of that time is confirmed by the ,chinese ,annals4 ,in the latter records the brightness is compared to that of ,venus1 and even with that of the moon6 ,the comparison with the moon was probably an exaggeration1 but the comet doubtless made a very brilliant show4 ,in the ,bayeux ,tapestry the inscription on the wall behind the spectators reads3 isti mirant stella4 ,now1 this is bad ,latin1 and ,mr4 ,w4 ,t4 ,lynn has made the interesting suggestion that some of the letters are hidden by the buildings in front and that the real sentence is isti mirantur stellam4#bjb ,the present writer has examined the copy of the ,bayeux ,tapestry which is in the ,dublin ,museum1 and thinks that ,mr4 ,lynn's suggestion seems very plausible4 ,but the last letter of stellam is apparently hidden by the comet's tail1 which does not seem very probable6 ,the conditions under which the comet will appear in #aiaj are not unlike those of #ajff and #aade4 ,in each year the comet was discovered as a morning star1 then lost in the sun's rays2 on its emergence it was near the earth and moved with great rapidity1 finally becoming stationary in the neighbourhood of ,hydra1 where it was lost to view4#bjc ,in #aiaj it will probably be an evening star before ,march #ag1 and after ,may #aa1 making a near approach to the earth about ,may #ab4 ,about this time its apparent motion in the sky will be very rapid4 ,as1 however1 periodical comets--such as ,halley's--seem to become fainter at each return1 great expectations with reference to its appearance in #aiaj should not be indulged in4 ,the appearance of ,halley's comet in ,a4,d4 #abbb is thus described by ,pingr--a great authority on comets--7quoting from an ancient writer7-- ,in autumn1 that is to say in the months of ,august and ,september1 a star of the first magnitude was seen1 very red1 and accompanied by a great tail which extended towards the top of the sky in the form of a cone extremely pointed4 ,it appeared to be very near the earth4 ,it was observed 7at first87 near the place of the setting sun in the month of ,december4 ,with reference to its appearance in the year #adef1 when it was of vivid brightness1 and had a tail of #fj in length1 ,admiral ,smyth says1#bjd ,to its malign influence were imputed the rapid successes of ,mahomet ,,ii41 which then threatened all ,christendom4 ,the general alarm was greatly aggravated by the conduct of ,pope ,callixtus ,,iii41 who1 though otherwise a man of abilities1 was a poor astronomer2 for that pontiff daily ordered the church bells to be rung at noon-tide1 extra ,ave-,marias to be repeated1 and a special protest and excommunication was composed1 exorcising equally the ,devil1 the ,turks1 and the comet4 ,with reference to this story1 ,mr4 ,g4 ,f4 ,chambers points out#bje that it is probably based on a passage in ,platina's ,vit ,pontificum4 ,but in this passage there is no mention made of excommunication or exorcism1 so that the story1 which has long been current1 is probably mythical4 ,in confirmation of this view1 the ,rev4 ,w4 ,f4 ,rigge has shown conclusively#bjf that no bull was ever issued by ,pope ,callixtus ,,iii4 containing a reference to any comet4 ,the story would therefore seem to be absolutely without foundation1 and should be consigned to the limbo of all such baseless myths4 ,with reference to the appearance of ,halley's comet1 at his last return in #ahce1 ,sir ,john ,herschel1 who observed it at the ,cape of ,good ,hope1 says-- ,among the innumerable stars of all magnitudes1 from the ninth downwards1 which at various times were seen through it1 and some extremely near to the nucleus 7though not exactly on it7 there never appeared the least ground for presuming any extinction of their light in traversing it4 ,very minute stars indeed1 on entering its brightest portions1 were obliterated1 as they would have been by an equal illumination of the field of view2 but stars which before their entry appeared bright enough to bear that degree of illumination1 were in no case1 so far as ,i could judge1 affected to a greater extent than they would have been by so much lamp-light artificially introduced4#bjg ,it is computed by ,prof4 ,j4 ,holetschak that1 early in ,october1 #aiji1 ,halley's comet should have the brightness of a star of about #ad-a_/b magnitude4#bjh ,it should then--if not detected before--be discoverable with some of the large telescopes now available4 ,according to the computations of ,messrs4 ,cowell and ,crommelin1 the comet should enter ,pisces from ,aries in ,january1 #aiaj4 ,travelling westward towards the star ,greek3 g ,piscium until the beginning of ,may1 and then turning eastward again1 it will travel back through the constellations ,cetus1 ,orion1 ,monoceros1 ,hydra1 and ,sextans4 ,from this it seems that observers in the southern hemisphere will have a better view of the comet than those in northern latitudes4 ,the computed brightness varies from #a on ,january #b1 #aiaj1 to #aaab on ,may #aj4 ,but the actual brightness of a comet does not always agree with theory4 ,it is sometimes brighter than calculation would indicate4 ,according to ,prof4 ,o4 ,c4 ,wendell1 ,halley's comet will1 on ,may #ab1 #aiaj1 approach the earth's orbit within #df millions of miles2 and he thinks that possibly the earth may encounter some meteors1 which are presumably connected with the comet4 ,he has computed the radiant point of these meteors 7that is1 the point from which they appear to come71 and finds its position to be ,r4,a4 #bb;h #dbm#i1 ,decl4 ,n4 #a #ah'4 ,this point lies a little south-west of the star ,greek3 b ,piscium4 ,according to ,dr4 ,smart1 the comet will1 on ,june #b1 cross the ,equator thirteen degrees south of ,regulus1 and will then move slowly in the direction of ,greek3 ph ,leonis4 ,the comet will be at its descending node on the ecliptic in the morning of ,may #af1 and the earth will pass through the node on the comet's orbit about two and a half days later4 ,the comet's orbit at the node is about #ac million miles within that of the earth4 ,matter repelled from the comet's nucleus by the sun with a velocity of about #baf1jjj miles per hour1 would just meet the earth when crossing the comet's orbit plane4 ,matter expelled with a velocity of #hj1jjj miles per hour1 as in the case of ,comet ,morehouse1 would require seven days for the journey4 ,cometary matter is said to have acquired greater velocities than this1 for 7according to ,webb1 who quotes ,chacornac7 ,comet ,,ii41 #ahfb1 shot luminous matter towards the sun1 with a velocity of nearly #bbjj miles per second4 ,it is therefore possible that matter thrown off by the comet at the node may enter our atmosphere1 in which case we must hope that cyanogen1 which so often appears in cometary spectra1 may not be inconveniently in evidence4#bji ,cyanogen is1 of course1 a poisonous gas1 but cometary matter is so rarefied that injurious effects on the earth need not be feared4 ,if we can believe the accounts which have been handed down to us1 some very wonderful comets were visible in ancient times4 ,the following may be mentioned3-- ,b4,c4 #afe4 ,the sun is said to have been seen for several hours in the night4 ,if this was a comet it must have been one of extraordinary brilliancy4#baj ,b4,c4 #adf4 ,after the death of ,demetrius1 king of ,syria1 the father of ,demetrius and ,antiochus1 a little before the war in ,achaia1 there appeared a comet as large as the sun4 ,its disc was first red1 and like fire1 spreading sufficient light to dissipate the darkness of night2 after a little while its size diminished1 its brilliancy became weakened1 and at length it entirely disappeared4#baa ,b4,c4 #acd4 ,it is recorded that at the birth of ,mithridates a great comet appeared which occupied the fourth part of the sky1 and its brilliancy was superior to that of the sun4 787#bab ,b4,c4 #ge4 ,a comet is described as equal in size to the moon1 and giving as much light as the sun on a cloudy day4 767#bac ,a4,d4 #eca4 ,in this year a great comet was observed in ,europe and ,china4 ,it is described as a very large and fearful comet1 and was visible in the west for three weeks4 ,hind thinks that this was an appearance of ,halley's comet1#bad and this has been confirmed by ,mr4 ,crommelin4 ,a4,d4 #hac1 ,august #d4 ,a comet is said to have appeared on this date1 of which the following curious description is given3 ,it resembled two moons joined together2 they separated1 and having taken different forms1 at length appeared like a man without a head4 767#bae ,a4,d4 #hic4 ,a great comet is said to have appeared in this year with a tail #ajj in length1 which afterwards increased to #bjj6baf ,a4,d4 #adjb4 ,a comet appeared in ,february of this year1 which was visible in daylight for eight days4 ,on ,palm ,sunday1 ,march #ai1 its size was prodigious4 ,another comet1 visible in the daytime1 was seen from ,june to ,september of the same year4 ,when the orbit of the comet known as #ahhi ,v was computed1 it was found that it had passed through ,jupiter's system in #ahhf 7,july #ah-ba74 ,the calculations show that it must have passed within a distance of #aab1cjj miles of the planet itself--or less than half the moon's distance from the earth--and its centre may possibly have grazed the surface of ,jupiter4#bag ,sir ,john ,herschel thought that the great comet of #ahfa was by far the brightest comet he had ever seen1 those of #ahaa and #aheh 7,donati's7 not excepted4#bah ,prof4 ,kreutz found its period of revolution round the sun to be about #dji years1 with the plane of the orbit nearly at right angles to the plane of the ecliptic4 99 99 99 99 99 ,on ,november #i1 #agie1 ,sir ,william ,herschel saw the comet of that year pass centrally over a small double star of the #aath and #abth magnitudes1 and the fainter of the two components remained distinctly visible during the comet's transit over the star4 ,this comet was an appearance of the comet now known as ,encke's4#bai ,struve saw a star of the #ajth magnitude through nearly the brightest part of ,encke's comet on ,november #g1 #ahbh1 but the star's light was not dimmed by the comet4 ,sir ,john ,herschel saw a cluster of stars of the #afth or #agth magnitude through ,biela's comet1 although the interposed cometary matter must have been at least #ej1jjj miles in thickness4#bbj ,bessel found that on ,september #bi1 #ahce1 a star of the #ajth magnitude shone with undimmed lustre through the tail of ,halley's comet within #h seconds of arc of the central point of the head4 ,at ,dorpat 7,russia7 ,struve saw the same star in conjunction only #bb from the brightest point of the comet4 ,the star remained continuously visible1 and its light was not perceptibly diminished whilst the nucleus of the comet seemed to be almost extinguished before the radiance of the small star of the #ith or #ajth magnitude4#bba ,webb says-- ,donati saw a #g mg4 star enlarged so as to show a sensible disc1 when the nucleus of comet ,,iii41 #ahfj1 passed very near it4 ,stars are said to have started1 or become tremulous1 during occultations by comets4 ,birmingham observed the comet of ,encke illuminated by a star over which it passed1 ,august #bc1 #ahfh2 and ,klein1 in #ahfa1 remarked an exceptional twinkling in #e mg4 stars involved in the tail4#bbb ,the comet of #agbi had the greatest perihelion distance of any known comet2#bbc that is1 when nearest to the sun1 it did not approach the central luminary within four times the earth's distance from the sun6 ,barnard's comet1 #ahhi ,i41 although it never became visible to the naked eye1 was visible with a telescope from ,september #b1 #ahhh1 to ,august #ah1 #ahij1 or #gae days--the longest period of visibility of any comet on record4 ,when last seen it was #f-a_/d times the earth's distance from the sun1 or about #ehj millions of miles1#bbd or beyond the orbit of ,jupiter6 ,messier1 who was called the comet ferret1 discovered all his comets with a small #b-;foot telescope of #b-a_/d inches aperture1 magnifying #e times1 and with a field of #d4bbe ,it is a very curious fact that ,sir ,william ,herschel1 during all his star-gaugings and sweeps for nebul1 never discovered a comet2#bbf that is an object which was afterwards proved to be a comet4 ,possibly1 however1 some of his nebul which are now missing1 may have been really comets4 ,sir ,william ,herschel found the diameter of the head of the great comet of #ahaa to be #abg1jjj miles4 ,the surrounding envelope he estimated to be at least #fdc1jjj miles1 or about three-fourths of the sun's diameter4 ,on a drawing of the tails of the great comet of #agdd given in a little book printed in ,berlin in that year1 no less than #ab tails are shown6 ,these vary in length and brightness4 ,a copy of this drawing is given in ,copernicus4#bbg ,the observations were made by einen geschichten ,frauenzimmer1 who ,dr4 ,dreyer identifies with ,christian ,kirch1 or one of her two sisters1 daughters of the famous ,gottfried and ,maria ,margaretta ,kirch 7,idem1 p4 #ajg74 ,dr4 ,dreyer thinks that the drawing seems to have been carefully made1 and not to be a mere rough sketch as ,i had at first supposed 7,idem1 p4 #ahe74 ,the tails of some comets were of immense length4 ,that of the comet of #agfi had an absolute length of #ch millions of miles4 ,that of #afhj1 #if million of miles1 or more than the sun's distance from the earth4 ,according to ,sir ,william ,herschel1 the tail of the great comet of #ahaa was over #ajj millions of miles in length4 ,that of the great comet of #ahdc--one of the finest in history--is supposed to have reached a length of #aej millions of miles6#bbh ,in width the tails of comets were in some cases enormous4 ,according to ,sir ,william ,herschel1 the tail of the comet of #ahaa had a diameter of #ae millions of miles6 ,its volume was1 therefore1 far greater than that of the sun6#bbh ,according to ,hevelius the comet of #afeb was of such a magnitude that it resembled the moon when half full2 only it shone with a pale and dismal light4#bbi ,halley's comet at its next appearance will be examined with the spectroscope for the first time in its history4 ,at its last return in #ahce1 the spectroscope had not been invented4 ,for the great comet of #ahaa1 ,arago computed a period of #cjfe years2 and ,encke found a period of #hhjj years for the great comet of #afhj4bcj ,the variation in the orbital velocity of some comets is enormous4 ,the velocity of the comet of #afhj when passing round the sun 7perihelion7 was about #bab miles a second6 ,whereas at its greatest distance from the sun 7aphelion7 the velocity is reduced to about #aj feet a second6 ,,chapter ,,xii ,meteors ,mr4 ,denning thinks that the meteor shower of the month of ,may1 known as the ,aquarids1 is probably connected with ,halley's comet4 ,the meteors should be looked for after #a a4m4 during the first week in ,may1 and may possibly show an enhanced display in ,may1 #aiaj1 when ,halley's comet will be near the sun and earth4#bca ,on ,november #bi1 #aije1 ,sir ,david ,gill observed a fireball with an apparent diameter equal to that of the moon1 which remained visible for #e minutes and disappeared in a hazy sky4 ,observed from another place1 ,mr4 ,fuller found that the meteor was visible #b hours later6 ,sir ,david ,gill stated that he does not know of any similar phenomenon4#bcb ,mr4 ,denning finds that swiftly moving meteors become visible at a greater height above the earth's surface than the slower ones4 ,thus1 for the ,leonids and ,perseids1 which are both swift1 it has been found that the ,leonids appear at an average height of #hd miles1 and disappear at a height of #ef miles2 and the ,perseids at #hj and #ed miles respectively4 ,on the other hand1 the mean height of the very slow meteors average about #fe miles at the beginning and #ch miles at the end of their appearance4#bcc ,during the night of ,july #ba-bb1 #ahif1 ,mr4 ,william ,brooks1 the well-known astronomer1 and director of the ,smith ,observatory at ,geneva 7,new ,york71 saw a round dark body pass slowly across the moon's bright disc1 the moon being nearly full at the time4 ,the apparent diameter of the object was about one minute of arc1 and the duration of the transit #c or #d seconds1 the direction of motion being from east to west4 ,on ,august #bb of the same year1 ,mr4 ,gathman 7an ,american observer7 saw a meteor crossing the sun's disc1 the transit lasting about #h seconds4#bcd ,a meteor which appeared in ,italy on ,july #g1 #ahib1 was shown by ,prof4 von ,niessl to have had an ascending path towards the latter end of its course6 ,the length of its path was computed to be #fhc miles4 ,when first seen1 its height above the earth was about #db miles1 and when it disappeared its height had increased to about #ih miles1 showing that its motion was directed upwards6#bce ,in the case of the fall of meteoric stones1 which occasionally occur1 it has sometimes been noticed that the sound caused by the explosion of the meteorite1 or its passage through the air1 is heard before the meteorite is seen to fall4 ,this has been explained by the fact that owing to the resistance of the air to a body moving at first with a high velocity its speed is so reduced that it strikes the earth with a velocity less than that of sound4 ,hence the sound reaches the earth before the body strikes the ground4#bcf ,the largest meteoric stone preserved in a museum is that known as the ,anighita1 which weighs #cf-a_/b tons1 and was found at ,cape ,york in ,greenland4 ,it was brought to the ,american ,museum of ,natural ,history by ,commander ,r4 ,e4 ,peary1 the ,arctic explorer4 ,the second largest known is that of ,bacubirito in ,mexico1 the weight of which is estimated at #bg-a_/b tons4 ,the third largest is that known as the ,williamette1 which was found in #aijb near the town of that name in ,western ,oregon 7,u4,s4,a474 ,it is composed of metallic nickel-iron1 and weighs about #ac-a_/b tons4 ,it is now in the ,american ,museum of ,natural ,history4 ,a large meteorite was actually seen1 from the deck of the steamer ,african ,prince1 to fall into the ,atlantic ,ocean1 on ,october #g1 #aijf6 ,the captain of the vessel1 ,captain ,anderson1 describes it as having a train of light resembling an immense broad electric-coloured band1 gradually turning to orange1 and then to the colour of molten metal4 ,when the meteor came into the denser atmosphere close to the earth1 it appeared1 as nearly as is possible to describe it1 like a molten mass of metal being poured out4 ,it entered the water with a hissing noise close to the ship4#bcg ,this was a very curious and perhaps unique phenomenon1 and it would seem that the vessel had a narrow escape from destruction4 ,in ,central ,arizona 7,u4,s4,a47 there is a hill called ,coon ,butte1 or ,coon ,mountain4 ,this so-called mountain rises to a height of only #acj to #afj feet above the surrounding plain1 and has on its top a crater of #ecj to #efj feet deep2 the bottom of the crater--which is dry--being thus #djj feet below the level of the surrounding country4 ,this so-called crater is almost circular and nearly three-quarters of a mile in diameter4 ,it has been suggested that this crater was formed by the fall of an enormous iron meteorite1 or small asteroid4 ,the crater has been carefully examined by a geologist and a physicist4 ,from the evidence and facts found1 the geologist 7,mr4 ,barringer7 states that they do not leave1 in my mind1 a scintilla of doubt that this mountain and its crater were produced by the impact of a huge meteorite or small asteroid4 ,the physicist 7,mr4 ,tilghmann7 says that he is justified1 under due reserve as to subsequently developed facts1 in announcing that the formation at this locality is due to the impact of a meteor of enormous and unprecedented size4 ,there are numerous masses of meteoric iron in the vicinity of the crater4 ,the so-called ,canyon ,diabolo meteorite was found in a canyon of that name about #b-a_/b miles from the ,coon ,mountain4 ,the investigators estimate that the great meteoric fall took place not more than #ejjj years ago1 perhaps much less4 ,cedar trees about #gjj years old are now growing on the rim of the mountain4 ,from the results of artillery experiments1 ,mr4 ,gilbert finds that a spherical projectile striking solid limestone with a velocity of #ahjj feet a second will penetrate to a depth of something less than two diameters1 and from this ,mr4 ,l4 ,fletcher concludes that a meteorite of large size would not be prevented by the earth's atmosphere from having a penetration effect sufficient for the production of such a crater4#bch ,the meteoric origin of this remarkable crater is strongly favoured by ,mr4 ,g4 ,p4 ,merrill1 ,head ,curator of ,geology1 ,u4,s4 ,national ,museum4 ,the ,canyon ,diabolo meteorite above referred to was found to contain diamonds6 some black1 others transparent4 ,so some have said that the diamond is a gift from ,heaven1 conveyed to earth in meteoric showers4#bci ,but diamond-bearing meteorites would seem to be rather a freak of nature4 ,it does not follow that all diamonds had their origin in meteoric stones4 ,the mineral known as periodot is frequently found in meteoric stones1 but it is also a constituent of terrestrial rocks4 ,in the year #ahhb it was stated by ,dr4 ,halm and ,dr4 ,weinhand that they had found fossil sponges1 corals1 and crinoids in meteoric stones6 ,dr4 ,weinhand thought he had actually determined three genera6#bdj ,but this startling result was flatly contradicted by ,carl ,vogt1 who stated that the supposed fossils are merely crystalline conformations4#bda ,some meteorites contain a large quantity of occluded gases1 hydrogen1 helium1 and carbon oxides4 ,it is stated that ,dr4 ,odling once lighted up the theatre of the ,royal ,institution with gas brought down from interstellar space by meteorites6#bdb ,on ,february #aj1 #ahif1 a large meteorite burst over ,madrid with a loud report4 ,the concussion was so great that many windows in the city were broken1 and some partitions in houses were shaken down6#bdc ,a very brilliant meteor or fireball was seen in daylight on ,june #i1 #aijj1 at #b;h #eem p4m4 from various places in ,surrey1 ,sussex1 and near ,london4 ,calculations showed that the meteor began #ei miles in height over a point #aj miles east of ,valognes1 near ,cherbourg1 ,france4 ,meteor ended #bc miles in height1 over ,calais1 ,france4 ,length of path #age miles4 ,radiant point1 #bhj1 #ab4bdd ,it was decided some years ago in the ,american ,supreme ,court that a meteorite1 though a stone fallen from heaven1 belongs to the owner of the freehold interest in the land on which it falls1 and not to the tenant4#bde ,with reference to the fall of meteoric matter on the earth1 ,mr4 ,proctor says1 ,it is calculated by ,dr4 ,kleiber of ,st4 ,petersburgh that #dbej lbs4 of meteoric dust fall on the earth every hour--that is1 #ei tons a day1 and more than #aa1dce tons a year4 ,i believe this to be considerably short of the truth4 ,it sounds like a large annual growth1 and the downfall of such an enormous mass of meteoric matter seems suggestive of some degree of danger4 ,but in reality1 ,dr4 ,kleiber's estimate gives only about #be millions of pounds annually1 which is less than #b ounces annually to each square mile of the earth's surface1#bdf a quantity which is1 of course1 quite insignificant4 ,according to ,humboldt1 ,chladni states that a ,franciscan monk was killed by the fall of an arolite at ,milan in the year #affj4bdg ,humboldt also mentions the death by meteoric stones of a monk at ,crema on ,september #d1 #aeaa1 and two ,swedish sailors on board ship in #afgd4bdh ,it is a curious fact that1 according to ,olbers1 no fossil meteoric stones have ever been discovered4#bdi ,considering the number which are supposed to have fallen to the earth in the course of ages1 this fact seems a remarkable one4 ,on ,may #aj1 #ahgi1 a shower of meteorites fell at ,eitherville1 ,iowa 7,u4,s4,a474 ,some of the fragments found weighed #dcg1 #agj1 #ib-a_/b1 #bh1 #aj-a_/b1 #d and #b lbs4 in weight4 ,in the following year 7#ahhj7 when the prairie grass had been consumed by a fire1 about #ejjj pieces were found from the size of a pin to a pound in weight4#bej ,according to ,prof4 ,silvestria of ,catania1 a shower of meteoric dust mixed with rain fell on the night of ,march #bi1 #ahhj4 ,the dust contained a large proportion of iron in the metallic state4 ,in size the particles varied from a tenth to a hundredth of a millimetre4#bea ,it is sometimes stated that the average mass of a shooting star is only a few grains4 ,but from comparisons with an electric arc light1 ,prof4 ,w4 ,h4 ,pickering concludes that a meteor as bright as a third magnitude star1 composed of iron or stone1 would probably have a diameter of #f or #g inches4 ,an average bright fireball would perhaps measure #e or #f feet in diameter4#beb ,in the ,book of ,joshua we are told that the ,,lord cast down great stones from heaven upon them unto ,azekah1 and they died 7,joshua x4 #aa74 ,in the latter portion of the verse hailstones are mentioned1 but as the original ,hebrew word means stones in general 7not hailstones71 it seems very probable that the stones referred to were arolites4#bec ,the stone mentioned in the ,acts of the ,apostles1 from which was found the image which fell down from ,jupiter 7,acts xix4 #ce71 was evidently a meteoric stone4#bec ,the famous stone in the ,caaba at ,mecca1 is probably a stone of meteoric origin4#bec ,i ,stones from ,heaven6 ,can you wonder1 ,you who scrutinize the ,earth1 ,at the love and veneration ,they received before the birth ,of our scientific methods8 ,,ii ,stones from ,heaven6 we can handle ,fragments fallen from realms of ,space2 ,oh6 the marvel and the mystery1 ,could we understand their place ,in the scheme of things created6 ,,iii ,stones from ,heaven6 ,with a mighty ,comet whirling formed they part8 ,fell they from their lofty station ,like a brilliant fiery dart1 ,hurl'd from starry fields of ,night8#bed ,,chapter ,,xiii ,the ,zodiacal ,light and ,gegenschein ,according to ,gruson and ,brugsch1 the ,zodiacal ,light was known in ancient times1 and was even worshipped by the ,egyptians4 ,strabo does not mention it2 but ,diodorus ,siculus seems to refer to it 7,b4,c4 #cgc71 and he probably obtained his information from some ,greek writers before his time1 possibly from ,zenophon1 who lived in the sixth century ,b4,c4#bee ,coming to the ,christian era1 it was noticed by ,nicephorus1 about #daj ,b4,c4 ,in the ,koran1 it is called the false ,aurora2 and it is supposed to be referred to in the ,rubiyt of ,omar ,khayyam1 the ,persian astronomical poet1 in the second stanza of that poem 7,edward ,fitzgerald's translation7-- ,dreaming when ,dawn's ,left ,hand was in the ,sky1#bef ,i heard a voice within the ,tavern cry1 ,awake1 my ,little ones1 and fill the ,cup1 ,before ,life's ,liquor in its ,cup be dry4 ,it was observed by ,cassini in #affh1beg and by ,hooke in #agje4 ,a short description of its appearance will be found in ,childrey's ,britannia ,baconica 7#affa71 p4 #ahc4 ,the finest displays of this curious light seem to occur between the middle of ,january and the middle of ,february4 ,in ,february1 #ahef1 ,secchi found it brighter than he had ever seen it before4 ,it was yellowish towards the axis of the cone1 and it seemed to be brighter than the ,milky ,way in ,cygnus4 ,he described it as un grande spectacle4 ,in the middle of ,february1 #ahff1 ,mr4 ,lassell1 during his last residence in ,malta1 saw a remarkable display of the ,zodiacal ,light4 ,he found it at least twice as bright as the brightest part of the ,milky ,way1 and much brighter than he had previously seen it4 ,he found that the character of its light differed considerably from that of the ,milky ,way4 ,it was of a much redder hue than the ,galaxy4 ,in #ahgd very remarkable displays were seen in the neighbourhood of ,london in ,january and ,february of that year2 and in #ahge on ,january #bd1 #be1 and #cj4 ,on ,january #bd it was noticed that the light was distinctly reddish and much excelled in brightness any portion of the ,milky ,way4 ,humboldt1 who observed it from ,andes 7at a height of #ac1jjj to #ae1jjj feet71 from ,venezuela and from ,cumana1 tells us that he has seen the ,zodiacal ,light equal in brightness to the ,milky ,way in ,sagittarius4 ,as probably many people have never seen the light1 a caution may be given to those who care to look for it4 ,it is defined by the ,rev4 ,george ,jones1 ,chaplain to the ,united ,states' ,japan ,expedition 7#ahec-ee71 as a brightness that appears in the western sky after sunset1 and in the east before sunrise2 following nearly or quite the line of the ecliptic in the heavens1 and stretching upwards to various elevations according to the season of the year4 ,from the description some might suppose that the light is visible immediately after sunset4 ,but this is not so2 it never appears until twilight is over and the night has fully set in4 ,the light is usually seen after sunset or before sunrise4 ,but attempts have recently been made by ,prof4 ,simon ,newcomb to observe it north of the sun4 ,to avoid the effects of twilight the sun must be only slightly more than #ah below the horizon 7that is1 a little before or after the longest day74 ,this condition limits the place of observation to latitudes not much south of #df2 and to reduce atmospheric absorption the observing station should be as high as possible above the level of the sea4 ,prof4 ,newcomb1 observing from the ,brienzer ,rothorn in ,switzerland 7latitude #df #dg' ,n41 longitude #h #c' ,e471 succeeded in tracing the light to a distance of #ce north of the sun4 ,it would seem1 therefore1 that the ,zodiacal ,light envelops the sun on all sides1 but has a greater extension in the direction of the ecliptic4#beh ,from observations at the ,lick ,observatory1 ,mr4 ,e4 ,a4 ,fath found an extension of #df north of the sun4#bei ,from observations of the light made by ,prof4 ,barnard at the ,yerkes ,observatory during the summer of #aijf1 he finds that it extends to at least #fe north of the sun1 a considerably higher value than that found by ,prof4 ,newcomb4#bfj ,the difference may perhaps be explained by actual variation of the meteoric matter producing the light4 ,prof4 ,j4 ,h4 ,poynting thinks that possibly the ,zodiacal ,light is due to the dust of long dead comets4#bfa ,from careful observations of the light1 ,mr4 ,gavin ,j4 ,burns finds that its luminosity is some #dj or #ej per cent4 brighter than the background of the sky4 ,prof4 ,newcomb has made a precisely similar remark about the luminosity of the ,milky ,way1 viz4 that it is surprisingly small4 ,this agrees with my own observations during many years4 ,it is only on the finest and clearest nights that the ,milky ,way forms a conspicuous object in the night sky4 ,and this only in the country4 ,the lights of a city almost entirely obliterate it4 ,mr4 ,burns finds that the ,zodiacal ,light appears to be of a yellowish tint2 or if we call it white1 then the ,milky ,way is comparatively of a bluish tint4 ,during my residence in the ,punjab the ,zodiacal ,light seemed to me constantly visible in the evening sky in the spring months4 ,in the west of ,ireland ,i have seen it nearly as bright as the brightest portions of the ,milky ,way visible in this country 7,february #bj1 #ahij74 ,the meteoric theory of the light seems to be the one now generally accepted by astronomers1 and in this opinion ,i fully concur4 ,from observations made in ,jamaica in the years #ahii and #aija1 ,mr4 ,maxwell ,hall arrived at the conclusion that the ,zodiacal ,light is caused by reflection of sunlight from masses of meteoric matter still contained in the invariable plane1 which may be considered the original plane of the solar system4#bfb ,according to ,humboldt1 ,cassini believed that the ,zodiacal ,light consisted of innumerably small planetary bodies revolving round the sun4#bfc ,,the ,,gegenschein1 or ,,counter-,,glow4--,this is a faint patch of light seen opposite the sun's place in the sky1 that is on the meridian at midnight4 ,it is usually elliptical in shape1 with its longer axis lying nearly in the plane of the ecliptic4 ,it seems to have been first detected by ,brorsen 7the discoverer of the short-period comet of #ahdf7 about the middle of the nineteenth century4 ,but it is not easy to see1 for the famous ,heis of ,mnster1 who had very keen eyesight1 did not succeed in seeing it for several years after ,brorsen's announcement4#bfd ,it was afterwards independently discovered by ,backhouse1 and ,barnard4 ,prof4 ,barnard's earlier observations seemed to show that the ,gegenschein does not lie exactly opposite to the sun1 but very nearly so4 ,he found its longitude is within one degree of #ahj1 and its latitude about #ac north of the ecliptic4#bfe ,but from subsequent observations he came to the conclusion that the differences in longitude and apparent latitude are due to atmospheric absorption1 and that the object really lies in the ecliptic and exactly opposite to the sun4#bff ,barnard finds that the ,gegenschein is not so faint as is generally supposed4 ,he says it is best seen by averted vision1 the face being turned #fj or #gj to the right or left1 and the eyes alone turned towards it4 ,it is invisible in ,june and ,december1 while in ,september it is round1 with a diameter of #bj1 and very distinct4 ,no satisfactory theory has yet been advanced to account for this curious phenomenon4 ,prof4 ,arthur ,searle of ,harvard attributes it to a number of asteroids too small to be seen individually4 ,when in opposition to the sun these would be fully illuminated and nearest to the earth4 ,its distance from the earth probably exceeds that of the moon4 ,dr4 ,johnson ,stoney thinks that the ,gegenschein may possibly be due to a tail of hydrogen and helium gases repelled from the earth by solar action2 this tail being visible to us by reflected sunlight4 ,it was observed under favourable circumstances in ,january and ,february1 #aijc1 by the ,french astronomer1 ,m4 ,f4 ,qunisset4 ,he found that it was better seen when the atmosphere was less clear1 contrary to his experience of the ,zodiacal ,light4 ,prof4 ,barnard's experience confirms this4 ,m4 ,qunisset notes that--as in the case of the ,zodiacal ,light--the southern border of the ,gegenschein is sharper than the northern4 ,he found that its brightness is less than that of the ,milky ,way between ,betelgeuse and ,greek3 g ,geminorum2 and thinks that it is merely a strengthening of the ,zodiacal ,light4#bfg ,a meteoritic theory of the ,gegenschein has been advanced by ,prof4 ,f4 ,r4 ,moulton1 which explains it by light reflected from a swarm of meteorites revolving round the sun at a distance of #icj1bdj miles outside the earth's orbit4 ,both the ,zodiacal ,light and ,gegenschein were observed by ,herr ,leo ,brenner on the evening of ,march #d1 #ahif4 ,he found the ,zodiacal ,light on this evening to be perhaps eight times brighter than the ,milky ,way in ,perseus4 ,the ,gegenschein distinctly visible as a round1 bright1 cloud-like nebula below ,leo 7,virgo71 and about twice the brightness of the ,milky ,way in ,monoceros between ,canis ,major and ,canis ,minor4#bfh ,humboldt thought that the fluctuations in the brilliancy of the ,zodiacal ,light were probably due to a real variation in the intensity of the phenomenon rather than to the elevated position of the observer4#bfi ,he says that he was astonished in the tropical climates of ,south ,america1 to observe the variable intensity of the light4 ,,chapter ,,xiv ,the ,stars ,pliny says that ,hipparchus ventured to count the stars1 a work arduous even for the ,deity4 ,but this was quite a mistaken idea4 ,those visible to the naked eye are comparatively few in number1 and the enumeration of those visible in an opera-glass--which of course far exceed those which can be seen by unaided vision--is a matter of no great difficulty4 ,those visible in a small telescope of #b-c_/d inches aperture have all been observed and catalogued2 and even those shown on photographs taken with large telescopes can be easily counted4 ,the present writer has made an attempt in this direction1 and taking an average of a large number of counts in various parts of the sky1 as shown on stellar photographs1 he finds a total of about #fd millions for the whole sky in both hemispheres4#bgj ,probably the total number will not exceed #ajj millions4 ,but this is a comparatively small number1 even when compared with the human population of our little globe4 ,with reference to the charts made by photography in the ,international scheme commenced some years ago1 it has now been estimated that the charts will probably contain a total of about #i1hed1jjj stars down to about the #adth magnitude 7#acg74 ,the catalogue plates 7taken with a shorter exposure7 will1 it is expected1 include about #b1fgf1ejj stars down to #aa-a_/b magnitude4 ,these numbers may1 however1 be somewhat increased when the work has been completed4#bga ,if this estimate proves to be correct1 the number of stars visible down to the #adth magnitude will be considerably less than former estimates have made it4 ,prof4 ,e4 ,c4 ,pickering estimates that the total number of stars visible on photographs down to the #afth magnitude 7about the faintest visible in the great ,lick telescope7 will be about #ej millions4#bgb ,in the present writer's enumeration1 above referred to1 many stars fainter than the #afth magnitude were included4 ,admiral ,smyth says1 with reference to ,sir ,william ,herschel--perhaps the greatest observer that ever lived--,as to ,sir ,william himself1 he could unhesitatingly call every star down to the #fth magnitude1 by its name1 letter1 or number4#bgc ,this shows great powers of observation1 and a wonderful memory4 ,on a photographic plate of the ,pleiades taken with the ,bruce telescope and an exposure of #f hours1 ,prof4 ,bailey of ,harvard has counted #cigb stars within an area #b square1 having ,alcyone at its centre4#bgd ,this would give a total of about #da millions for the whole sky1 if of the same richness4 ,with an exposure of #af hours1 ,prof4 ,h4 ,c4 ,wilson finds on an area of less that #aaj' square a total of #dfba stars4 ,he thinks1 ,that all of these stars belong to the ,pleiades group is not at all probable4 ,the great majority of them probably lie at immense distances beyond the group1 and simply appear in it by projection4#bgd ,he adds1 ,it has been found1 however1 by very careful measurements made during the last #ge years at the ,knigsbergh and ,yale ,observatories1 that of the sixty-nine brighter stars1 including those down to the #ith magnitude1 only eight show any certain movement with reference to ,alcyone4 ,since ,alcyone has a proper motion or drift of #f per century1 this means that all the brightest stars except the eight mentioned are drifting with ,alcyone and so form a true cluster1 at approximately the same distance from the earth4 ,six of the eight stars which show relative drift are moving in the opposite direction to the movement of ,alcyone1 and at nearly the same rate1 so that their motion is only apparent4 ,they are really stationary1 while ,alcyone and the rest of the cluster are moving past them4#bge ,this tends to show that the faint stars are really behind the cluster1 and are unconnected with it4 ,it is a popular idea with some people that the ,pole ,star is the nearest of all the stars to the celestial pole4 ,but photographs show that there are many faint stars nearer to the pole than the ,pole ,star4 ,the ,pole ,star is at present at a distance of #a #ac' from the real pole of the heavens1 but it is slowly approaching it4 ,the minimum distance will be reached in the year #bajd4 ,from photographs taken by ,m4 ,flammarion at the ,juvisy ,observatory1 he finds that there are at least #abh stars nearer to the pole than the ,pole ,star6 ,the nearest star to the pole was1 in the year #aijb1 a small star of about #ab-a_/b magnitude1 which was distant about #d minutes of arc from the pole4#bgf ,the estimated magnitude shows that the ,pole ,star is nearly #aj1jjj times brighter than this faint star6 ,it has been found that ,sirius is bright enough to cast a shadow under favourable conditions4 ,on ,march #bb1 #aijc1 the distinguished ,french astronomer ,touchet succeeded in photographing the shadow of a brooch cast by this brilliant star4 ,the exposure was #a;h #em4 ,martinus ,hortensius seems to have been the first to see stars in daylight1 perhaps early in the seventeenth century4 ,he mentions the fact in a letter to ,gassendi dated ,october #ab1 #afcf1 but does not give the date of his observation4 ,schickard saw ,arcturus in broad daylight early in #afcb4 ,morin saw the same bright star half an hour after sunset in ,march1 #afce4 ,some interesting observations were made by ,professors ,payne and ,h4 ,c4 ,wilson1 in the summer of #aijd1 at ,midvale1 ,montana 7,u4,s4,a471 at a height of #dgij feet above sea-level4 ,at this height they found the air very clear and transparent4 ,many more stars were visible at a glance1 and the familiar stars appeared more brilliant4444 ,in the great bright cloud of the ,milky ,way1 between ,greek3 b and ,greek3 g ,cygni1 one could count easily sixteen or seventeen stars1 besides the bright ones ,greek3 and ,greek3 ch1#bgg while at ,northfield it is difficult to distinctly see eight or nine with the naked eye4 ,some nebul and star fields were photographed with good results by the aid of a #b-a_/b-;inch ,darlot lens and #c hours' exposure4#bgh ,prof4 ,barnard has taken some good stellar photographs with a lens of only #a-a_/b inches in diameter1 and #d or #e inches focus belonging to an ordinary magic lantern6 ,he says that these photographs with the small lens show us in the most striking manner how the most valuable and important information may be obtained with the simplest means4#bgi ,with reference to the rising and setting of the stars due to the earth's rotation on its axis1 the late ,sir ,george ,b4 ,airy1 ,astronomer ,royal of ,england1 once said to a schoolmaster1 ,i should like to know how far your pupils go into the first practical points for which reading is scarcely necessary4 ,do they know that the stars rise and set8 ,very few people in ,england know it4 ,i once had a correspondence with a literary man of the highest rank on a point of ,greek astronomy1 and found that he did not know it6#bhj ,admiral ,smyth says1 ,i have been struck with the beautiful blue tint of the smallest stars visible in my telescope4 ,this1 however1 may be attributed to some optical peculiarity4 ,this bluish colour of small stars agrees with the conclusion arrived at by ,prof4 ,pickering in recent years1 that the majority of faint stars in the ,milky ,way have spectra of the ,sirian type and1 like that brilliant star1 are of a bluish white colour4 ,sir ,william ,herschel saw many stars of a redder tinge than other observers have noticed4 ,admiral ,smyth says1 ,this may be owing to the effect of his metallic mirror or to some peculiarity of vision1 or perhaps both4#bha ,the ancient astronomers do not mention any coloured stars except white and red4 ,among the latter they only speak of ,arcturus1 ,aldebaran1 ,pollux1 ,antares1 and ,betelgeuse as of a striking red colour4 ,to these ,al-,sufi adds ,alphard 7,greek3 a ,hydr74 ,sir ,william ,herschel remarked that no decidedly green or blue star has ever been noticed unassociated with a companion brighter than itself4 ,an exception to ,herschel's rule seems to be found in the case of the star ,greek3 b ,libr1 which ,admiral ,smyth called pale emerald4 ,mr4 ,george ,knott observed it on ,may #ai1 #aheb1 as beautiful pale green 7#cg inches achromatic1 power #hj71 and on ,may #i1 #ahgb1 as fine pale green 7#ee inches achromatic1 power #fe74 ,the motion of stars in the line of sight1 as shown by the spectroscope--should theoretically alter their brightness in the course of time2 those approaching the earth becoming gradually brighter1 while those receding should become fainter4 ,but the distance of the stars is so enormous that even with very high velocities the change would not become perceptible for ages4 ,prof4 ,oudemans found that to change the brightness of a star by only one-tenth of a magnitude--a quantity barely perceptible to the eye-a number of years would be necessary1 which is represented by the formula #eiaf years ----------------- parallax motion for a star approaching the earth1 and for a receding star #faie years ---------- p m ,this is in geographical miles1 #a geographical mile being equal to #dfa ,english miles4 ,reducing the above to ,english miles1 and taking an average for both approaching and receding stars1 we have #bg1ffj years ------------ p m where p parallax in seconds of arc1 and m radial velocity in ,english miles per second4 ,prof4 ,oudemans found that the only star which could have changed in brightness by one-tenth of a magnitude since the time of ,hipparchus is ,aldebaran4 ,this is taking its parallax as #jeb4 ,but assuming the more reliable parallax #jab found by ,dr4 ,elkin1 this period is #d-a_/c times longer4 ,for ,procyon1 the period would be #eejj years4#bhb ,the above calculation shows how absurd it is to suppose that any star could have gained or lost in brightness by motion in the line of sight during historical times4 ,the secular variation of stars is quite another thing4 ,this is due to physical changes in the stars themselves4 ,the famous astronomer ,halley1 the second ,astronomer ,royal at ,greenwich1 says 7,phil4 ,trans41 #agif71 ,supposing the number of #ast magnitude stars to be #ac1 at twice the distance from the sun there may be placed four times as many1 or #eb2 which with the same allowance would nearly represent the star we find to be of the #bnd magnitude4 ,so #i #ac1 or #aag1 for those at three times the distance2 and at ten times the distance #ajj #ac1 or #acjj stars2 of which distance may probably diminish the light of any of the stars of the #ast magnitude to that of the #fth1 it being but the hundredth part of what1 at their present distance1 they appear with4 ,this agrees with the now generally accepted light ratio of #beab for each magnitude1 which makes a first magnitude star #ajj times the light of a #fth magnitude4 ,on the #dth of ,march1 #agif1bhc the famous ,french astronomer ,lalande observed on the meridian a star of small #fth magnitude1 the exact position of which he determined4 ,on the #aeth of the same month he again observed the star1 and the places found for #ahjj refer to numbers #afbib-c of the reduced catalogue4 ,in the observation of ,march #d he attached the curious remark1 toile singulire 7the observation of ,march #ae is without note74 ,this remark of ,lalande has puzzled observers who failed to find any peculiarity about the star4 ,indeed1 the remark is a strange one for the observer of so many thousands of stars to attach unless there was really something singular in the star's aspect at the time4 ,on the evening of ,april #ah1 #ahhg1 the star was examined by the present writer1 and the following is the record in his observing book1 ,lalande's toile singulire 7#afbib-c7 about half a magnitude less than ,greek3 ,cancri4 ,with the binocular ,i see two streams of small stars branching out from it1 north preceding like the tails of comet4 ,this may perhaps have something to do with ,lalande's curious remark4 ,the star numbered #afdg in ,baily's ,flamsteed ,catalogue is now known to have been an observation of the planet ,uranus4#bhd ,prof4 ,pickering states that the fainter stars photographed with the #h-;inch telescope at ,cambridge 7,u4,s4,a47 are invisible to the eye in the #ae-;inch telescope4#bhe ,sir ,norman ,lockyer finds that the lines of sulphur are present in the spectrum of the bright star ,rigel 7,greek3 b ,orionis74#bhf ,about #h-a_/b south of the bright star ,regulus 7,greek3 a ,leonis7 is a faint nebula 7,h ,i1 #d ,sextantis74 ,on or near this spot the ,capuchin monk ,de ,rheita fancied he saw1 in the year #afdc1 a group of stars representing the napkin of ,s4 ,veronica--sudarium ,veronic sive faciem ,domini maxima similitudina in astris expressum4 ,and he gave a picture of the napkin and star group4 ,but all subsequent observers have failed to find any trace of the star group referred to by ,de ,rheita6#bhg ,the ,bible story of the star of the ,magi is also told in connection with the birth of the sun-gods ,osiris1 ,horus1 ,mithra1 ,serapis1 etc4#bhh ,the present writer has also heard it suggested that the phenomenon may have been an apparition of ,halley's comet6 ,but as this famous comet is known to have appeared in the year ,b4,c4 #aa1 and as the date of the ,nativity was probably not earlier than ,b4,c4 #e1 the hypothesis seems for this 7and other reasons7 to be inadmissible4 ,it has also been suggested that the phenomenon might have been an appearance of ,tycho ,brah's temporary star of #aegb1 known as the ,pilgrim star2 but there seems to be no real foundation for such an hypothesis4 ,there is no reason to think that temporary or new stars ever appear a second time4 ,admiral ,smyth has well said1 ,it checks one's pride to recollect that if our sun with the whole system of planets1 asteroids1 and moons1 and comets were to be removed from the spectator to the distance of the nearest fixed star1 not one of them would be visible1 except the sun1 which would then appear but as a star of perhaps the #bnd magnitude4 ,nay1 more1 were the whole system of which our globe forms an insignificant member1 with its central luminary1 suddenly annihilated1 no effect would be produced on those unconnected and remote bodies2 and the only annunciation of such a catastrophe in the ,sidereal ,times would be that a small star once seen in a distant quarter of the sky had ceased to shine4#bhi ,prof4 ,george ,c4 ,comstock finds that the average parallax of #fg selected stars ranging in brightness between the #ith and the #abth magnitude1 is of the value of #jjjea4bij ,this gives a distance representing a journey for light of about #fci years6 ,mr4 ,henry ,norris ,russell thinks that nearly all the bright stars in the constellation of ,orion are practically at the same distance from the earth4 ,his reasons for this opinion are3 7#a7 the stars are similar in their spectra and proper motions1 7#b7 their proper motions are small1 which suggests a small parallax1 and therefore a great distance from the earth4 ,mr4 ,russell thinks that the average parallax of these stars may perhaps be #jjje1 which gives a distance of about #fej light years4#bia ,according to ,sir ,norman ,lockyer's classification of the stars1 the order of increasing temperature is represented by the following1 beginning with those in the earliest stage of stellar evolution3--,nebul1 ,antares1 ,aldebaran1 ,polaris1 ,greek3 a ,cygni1 ,rigel1 ,greek3 e ,tauri1 ,greek3 b ,crucis4 ,then we have the hottest stars represented by ,greek3 e ,puppis1 ,greek3 g ,argus1 and ,alnitam 7,greek3 e ,orionis74 ,decreasing temperature is represented by 7in order71 ,achernar1 ,algol1 ,markab1 ,sirius1 ,procyon1 ,arcturus1 #ai ,piscium1 and the ,dark ,stars4#bib ,but other astronomers do not agree with this classification4 ,antares and ,aldebaran are by some authorities considered to be cooling suns4 ,according to ,ritter's views of the ,constitution of the ,celestial ,bodies1 if we divide the stars into three classes according to age corresponding to these three stages of development1 we shall assign to the first class1 ,a1 those stars still in the nebular phase of development2 to the second class1 ,b1 those in the transient stage of greatest brilliancy2 and to the class ,c1 those stars which have already entered into the long period of slow extinction4 ,it should be noted in this classification that we refer to relative and not absolute age1 since a star of slight mass passes through the successive phases of its development more rapidly than the star of greater mass4#bic ,ritter comes to the conclusion that the duration of the period in which the sun as a star had a greater brightness than at present was very short in comparison with the period in which it had and will continue to have a brightness differing only slightly from its present value4#bid ,in a valuable and interesting paper on ,the ,evolution of ,solar ,stars1#bie ,prof4 ,schuster says that measurements by ,e4 ,f4 ,nichols on the heat of ,vega and ,arcturus indicated a lower temperature for ,arcturus1 and confirms the conclusion arrived at on other grounds1 that the hydrogen stars have a higher temperature than the solar stars4 ,an inspection of the ultraviolet region of the spectrum gives the same result4 ,these different lines of argument1 all leading to the same result1 justify us in saying that the surface temperature of the hydrogen stars is higher than that of the solar stars4 ,an extension of the same reasoning leads to the belief that the helium stars have a temperature which is higher still4 ,hence we have ,schuster1 ,hale1 and ,sir ,william ,huggins in agreement that the ,sirian stars are hotter than the solar stars2 and personally ,i agree with these high authorities4 ,the late ,dr4 ,w4 ,e4 ,wilson1 however1 held the opinion that the sun is hotter that ,sirius6 ,schuster thinks that ,lane's law does not apply to the temperature of the photosphere and the absorbing layers of the sun and stars1 but only to the portions between the photosphere and the centre1 which probably act like a perfect gas4 ,on this view he says the interior might become hotter and hotter until the condensation had reached a point at which the laws of gaseous condensation no longer hold4 ,with reference to the stars having spectra of the #crd and #dth type 7usually orange and red in colour71 ,schuster says-- ,the remaining types of spectra belong to lower temperature still1 as in place of metallic lines1 or in addition to them1 certain bands appear which experiments show us invariably belong to lower temperature than the lines of the same element4 ,if an evolutionary process has been going on1 which is similar for all stars1 there is little doubt that from the bright-line stars down to the solar stars the order has been 7#a7 helium or ,orion stars1 7#b7 hydrogen or ,sirian stars1 7#c7 calcium or ,procyon stars1 7#d7 solar or ,capellan stars4 ,my investigations on ,the ,secular ,variation of ,starlight 7,studies in ,astronomy1 chap4 #ag1 and ,astronomical ,essays1 chap4 #ab7 based on a comparison of ,al-,sufi's star magnitudes 7tenth century7 with modern estimates and measures1 tend strongly to confirm the above views4 ,with regard to the #crd-type stars1 such as ,betelgeuse and ,mira ,ceti1 ,schuster says1 ,it has been already mentioned that observers differ as to whether their position is anterior to the hydrogen or posterior to the solar stars1 and there are valid arguments on both sides4 ,scheiner1 however1 shows1 from the behaviour of the lines of magnesium1 that stars of type ,i4 7,sirian7 are the hottest1 and type ,,iii4 the coolest1 and he says1 we have for the first time a direct proof of the correctness of the physical interpretation of ,vogel's spectral classes1 according to which class ,,ii4 is developed by cooling from ,i41 and ,,iii4 by a further process of cooling from ,,ii4#bif ,prof4 ,hale says that the resemblance between the spectra of sun-spots and of #crd-type stars is so close as to indicate that the same cause is controlling the relative intensities of many lines in both instances4 ,this cause1 as the laboratory work indicates1 is to be regarded as reduced temperature4#big ,according to ,prof4 ,schuster1 a spectrum of bright lines may be given by a mass of luminous gas1 even if the gas is of great thickness4 ,there is1 therefore1 no difficulty in explaining the existence of stars giving bright lines4 ,he thinks that the difference between bright line stars and those showing dark lines depends upon the rate of increase of the temperature from the surface towards the centre4 ,if this rate is slow1 bright lines will be seen4 ,if the rate of increase is rapid1 the dark-line spectrum shown by the majority of the stars will appear4 ,this rate1 he thinks1 is regulated by the gravitational force4 ,so that in the early stages of condensation bright lines are more likely to occur4 ,if the light is not fully absorbed1 both bright and dark lines of the same element may be visible in the same star4 ,schuster considers it quite possible that if we could remove the outer layers of the ,sun's atmosphere1 we should obtain a spectrum of bright lines4#bih ,m4 ,stratonoff finds that stars having spectra of the ,orion and ,sirian types--supposed to represent an early stage in stellar evolution--tend to congregate in or near the ,milky ,way4 ,star clusters in general show a similar tendency1 but to this law the globular clusters form an exception4#bii ,we may add that the spiral nebul--which seem to be scattered indifferently over all parts of the sky--also seem to form an exception2 for the spectra of these wonderful objects seem to show that they are really star clusters1 in which the components are probably relatively small2 that is1 small in comparison with our sun4 ,if we accept the hypothesis that suns and systems were evolved from nebul1 and if we consider the comparatively small number of nebul hitherto discovered in the largest telescopes--about half a million2 and if we further consider the very small number of red stars1 or those having spectra of the third and fourth types--usually considered to be dying-out suns--we seem led to the conclusion that our sidereal system is now at about the zenith of its life-history2 comparatively few nebul being left to consolidate into stars1 and comparatively few stars having gone far on the road to the final extinction of their light4 ,prof4 ,boss of ,albany 7,u4,s4,a47 finds that about forty stars of magnitudes from #c-a_/b to #g in the constellation ,taurus are apparently drifting together towards one point4 ,these stars are included between about ,r4,a4 #c;h #dgm to #e;h #dm1 and ,declination #e to #bc 7that is1 in the region surrounding the ,hyades74 ,these motions apparently converge to a point near ,r4,a4 #f;h1 ,declination #g 7near ,betelgeuse74 ,prof4 ,boss has computed the velocity of the stars in this group to be #def kilometres 7about #bh miles7 a second towards the vanishing point1 and he estimated the average parallax of the group to be #jjbe--;about #acj years' journey for light4 ,although the motions are apparently converging to a point1 it does not follow that the stars in question will1 in the course of ages1 meet at the vanishing point4 ,on the contrary1 the observed motions show that the stars are moving in parallel lines through space4 ,about #ae kilometres of the observed speed is due to the sun's motion through space in the opposite direction4 ,prof4 ,campbell finds from spectroscopic measures that of these forty stars1 nine are receding from the earth with velocities varying from #ab to #fj kilometres a second1 and twenty-three others with less velocities than #ch kilometres4#cjj ,it will be obvious that1 as there is a vanishing point1 the motion in the line of sight must be one of recession from the earth4 ,it has been found that on an average the parallax of a star is about one-seventh of its proper motion4#cja ,adopting ,prof4 ,newcomb's parallax of #jad for the famous star #ahcj ,groombridge1 the velocity perpendicular to the line of sight is about #aej miles a second4 ,the velocity in the line of sight--as shown by the spectroscope--is #ei miles a second approaching the earth4 ,compounding these two velocities we find a velocity through space of about #afa miles a second6 ,an eminent ,american writer puts into the mouth of one of his characters1 a young astronomer1 the following3-- ,i read the page ,where every letter is a glittering sun4 ,from an examination of the heat radiated by some bright stars1 made by ,dr4 ,e4 ,f4 ,nicholls in ,america with a very sensitive radiometer of his own construction1 he finds that we do not receive from ,arcturus more heat than we should from a candle at a distance of #e or #f miles4 ,with reference to the progressive motion of light1 and the different times taken by light to reach the earth from different stars1 ,humboldt says1 ,the aspect of the starry heavens presents to us objects of unequal date4 ,much has long ceased to exist before the knowledge of its presence reaches us2 much has been otherwise arranged4#cjb ,the photographic method of charting the stars1 although a great improvement on the old system1 seems to have its disadvantages4 ,one of these is that the star images are liable to disappear from the plates in the course of time4 ,the reduction of stellar photograph plates should1 therefore1 be carried out as soon as possible after they are taken4 ,the late ,dr4 ,roberts found that on a plate originally containing #cfd stars1 no less than #acj had completely disappeared in #i-a_/d years6 ,it has been assumed by some writers on astronomy that the faint stars visible on photographs of the ,pleiades are at practically the same distance from the earth as the brighter stars of the cluster1 and that consequently there must be an enormous difference in actual size between the brighter and fainter stars4 ,but there is really no warrant for any such assumption4 ,photographs of the vicinity show that the sky all round the ,pleiades is equally rich in faint stars4 ,it seems1 therefore1 more reasonable to suppose that most of the faint stars visible in the ,pleiades are really far behind the cluster in space4 ,for if all the faint stars visible on photographs belonged to the cluster1 then if we imagine the cluster removed1 a hole would be left in the sky1 which is of course utterly improbable1 and indeed absurd4 ,an examination of the proper motions tends to confirm this view of the matter1 and indicates that the ,pleiades cluster is a comparatively small one and simply projected on a background of fainter stars4 ,it has long been suspected that the famous star #fa ,cygni1 which is a double star1 forms a binary system--that is1 that the two stars composing it revolve round their common centre of gravity and move together through space4 ,but measures of parallax made by ,herman ,s4 ,davis and ,wilsing seem to show a difference of parallax between the two components of about #jjh of a second of arc4 ,this difference of parallax implies a distance of about #b-a_/d light years between the two stars1 and if this is correct1 the stars are too remote to form a binary system4 ,the proper motions of #eba and #eae seem to show that they are moving in nearly parallel directions2 but are probably slowly separating4 ,mr4 ,lewis1 however1 thinks that a physical connection probably exists4#cjc ,dante speaks of the four bright stars of the ,southern ,cross as emblematical of the four cardinal virtues1 ,justice1 ,temperance1 ,fortitude1 and ,prudence2 and he seems to refer to the stars ,canopus1 ,achernar1 and ,foomalhaut under the symbols of ,faith1 ,hope1 and ,charity4 ,the so-called ,false ,cross is said to be formed by the stars ,greek3 k1 ,greek3 d1 ,greek3 e1 and ,greek3 i of the constellation ,argo ,navis4 ,but it seems to me that a better 7although larger7 cross is formed by the stars ,greek3 a ,centauri and ,greek3 a1 ,greek3 b1 and ,greek3 g of ,triangulum ,australis4 ,mr4 ,monck has pointed out that the names of the brightest stars seem to be arranged alphabetically in order of colour1 beginning with red and ending with blue4 ,thus we have ,aldebaran1 ,arcturus1 ,betelgeuse1 ,capella1 ,procyon1 ,regulus1 ,rigel1 ,sirius1 ,spica and ,vega4 ,but as the origin of these names is different1 this must be merely a curious coincidence4#cjd ,and1 to my eye at least1 ,betelgeuse is redder than ,arcturus4 ,the poet ,longfellow speaks of the-- ,stars1 the thoughts of ,god in the heavens1#cje and ,drayton says-- ,the stars to me an everlasting book ,in that eternal register1 the sky4#cjf ,observing at a height of #ab1edj feet on the ,andes1 the late ,dr4 ,copeland saw ,sirius with the naked eye less than #aj minutes before sunset4#cjg ,he also saw ,jupiter #cm #dgs before sunset2 and the following bright stars--,canopus1 #jm #ebs before sunset2 ,rigel 7,greek3 b ,orionis7 #afm #cbs after sunset2 and ,procyon #aam #bhs after sunset4 ,from a height of #ab1jej feet at ,la ,paz1 ,bolivia1 he saw with the naked eye in ,february1 #ahhc1 ten stars in the ,pleiades in full moonlight1 and seventeen stars in the ,hyades4 ,he also saw ,greek3 s ,tauri double4#cjh ,humboldt says1 ,in whatever point the vault of heaven has been pierced by powerful and far-penetrating telescopic instruments1 stars or luminous nebul are everywhere discoverable1 the former in some cases not exceeding the #bjth or #bdth degree of telescopic magnitude4#cji ,but this is a mistake4 ,no star of even the #bjth magnitude has ever been seen by any telescope4 ,even on the best photographic plates it is doubtful that any stars much below the #ahth magnitude are visible4 ,to show a star of the #bjth magnitude--if such stars exist--would require a telescope of #add inches or #ab feet in aperture4 ,to show a star of the #bdth magnitude--if such there be--an aperture of #cc feet would be necessary6#caj ,it is a popular idea that stars may be seen in the daytime from the bottom of a deep pit or high chimney4 ,but this has often been denied4 ,humboldt says1 ,while practically engaged in mining operations1 ,i was in the habit1 during many years1 of passing a great portion of the day in mines where ,i could see the sky through deep shafts1 yet ,i never was able to observe a star4#caa ,stars may1 however1 be seen in the daytime with even small telescopes4 ,it is said that a telescope of #a inch aperture will show stars of the #bnd magnitude2 #b inches1 stars of the #crd magnitude2 and #d inches1 stars of the #dth magnitude4 ,but ,i cannot confirm this from personal observation4 ,it may be so1 but ,i have not tried the experiment4 ,sir ,george ,darwin says-- ,human life is too short to permit us to watch the leisurely procedure of cosmical evolution1 but the celestial museum contains so many exhibits that it may become possible1 by the aid of theory1 to piece together1 bit by bit1 the processes through which stars pass in the course of their evolutions4#cab ,the so-called telluric lines seen in the solar spectrum1 are due to water vapour in the earth's atmosphere4 ,as the light of the stars also passes through the atmosphere1 it is evident that these lines should also be visible in the spectra of the stars4 ,this is found to be the case by ,prof4 ,campbell1 ,director of the ,lick ,observatory1 who has observed all the principal bands in the spectrum of every star he has examined4#cac ,the largest proper motion now known is that of a star of the #h-a_/b magnitude in the southern hemisphere1 known as ,cordoba ,zone ,v4 ,no4 #bdc4 ,its proper motion is #hjg seconds of arc per annum1 thus exceeding that of the famous runaway star1 #ahcj ,groombridge1 which has a proper motion of #gje seconds per annum4 ,this greater motion is1 however1 only apparent4 ,measures of parallax show that the southern runaway is much nearer to us than its northern rival1 its parallax being #jcb1 while that of ,groombridge #ahcj is only #jad4 ,with these data the actual velocity across the line of sight can be easily computed4 ,that of the southern star comes out #hj miles a second1 while that of ,groombridge #ahcj is #adh miles a second4 ,the actual velocity of ,arcturus is probably still greater4 ,the poet ,barton has well said-- ,the stars6 the stars6 go forth at night1 ,lift up thine eyes on high1 ,and view the countless orbs of light1 ,which gem the midnight sky4 ,go forth in silence and alone1 ,this glorious sight to scan1 ,and bid the humbled spirit own ,the littleness of man4 ,,chapter ,,xv ,double and ,binary ,stars ,prof4 ,r4 ,g4 ,aitken1 the eminent ,american observer of double stars1 finds that of all the stars down to the #ith magnitude--about the faintest visible in a powerful binocular field-glass--#a in #ah1 or #a in #bj1 on the average1 are double1 with the component stars less than #e seconds of arc apart4 ,this proportion of double stars is not1 however1 the same for all parts of the sky2 while in some regions double stars are very scarce1 in other places the proportion rises to #a in #h4 ,for the well-known binary star ,castor 7,greek3 a ,geminorum71 several orbits have been computed with periods ranging from #bcb years 7,mdler7 to #ajja years 7,doberck74 ,but ,burnham finds that the orbit is absolutely indeterminate at this time1 and likely to remain so for another century or longer4#cad ,both components are spectroscopic binaries1 and the system is a most interesting one4 ,the well-known companion of ,sirius became invisible in all telescopes in the year #ahij1 owing to its near approach to its brilliant primary4 ,it remained invisible until ,august #bj1 #ahif1 when it was again seen by ,dr4 ,see at the ,lowell ,observatory4#cae ,since then its distance has been increasing1 and it has been regularly measured4 ,the maximum distance will be attained about the year #aibb4 ,the star ,greek3 b ,cephei has recently been discovered to be a spectroscopic binary with the wonderfully short period of #d;h #cdm #aas4 ,the orbital velocity is about #aj-a_/b miles a second1 and as this velocity is not very great1 the distance between the components must be very small1 and possibly the two component bodies are revolving in actual contact4 ,the spectrum is of the ,orion type4#caf ,according to ,slipher the spectroscopic binary ,greek3 g ,geminorum has the comparatively long period 7for a spectroscopic binary7 of about #c-a_/b years4 ,this period is comparable with that of the telescopic binary system1 ,greek3 d ,equulei 7period about #eg years74 ,the orbit is quite eccentric4 ,i have shown elsewhere#cag that ,greek3 g ,geminorum has probably increased in brightness since the time of ,al-,sufi 7tenth century74 ,possibly its spectroscopic duplicity may have something to do with the variation in its light4 ,with reference to the spectra of double stars1 ,mr4 ,maunder suggests that the fact of the companion of a binary star showing a ,sirian spectrum while the brighter star has a solar spectrum may be explained by supposing that1 on the theory of fission1 the smaller body when thrown off consisted of the lighter elements1 the heavier remaining in the principal star4 ,in other words1 in these cases spectral type depends upon original chemical constitution1 and not upon the stage of stellar development attained4#cah ,a curious paradox with reference to binary stars has recently come to light4 ,for many years it was almost taken for granted that the brighter star of a pair had a larger mass than the fainter component4 ,this was a natural conclusion1 as both stars are practically at the same distance from the earth4 ,but it has been recently found that in some binary stars the fainter component has actually the larger mass6 ,thus1 in the binary star ,greek3 e ,hydr1 the magnitude of the component stars are #c and #f1 indicating that the brighter star is about #af times brighter than the fainter component4 ,yet calculations by ,lewis show that the fainter star has #f times the mass of the brighter1 that is1 contains #f times the quantity of matter6 ,in the well-known binary #gj ,ophiuchi1 ,prey finds that the fainter star has about #d times the mass of the brighter6 ,in #he ,pegasi1 the brighter star is about #dj times brighter than its companion1 while ,furner finds that the mass of the fainter star is about #d times that of the brighter6 ,and there are other similar cases4 ,in fact1 in these remarkable combinations of suns the fainter star is really the primary1 and is1 so far as mass is concerned1 the predominant partner4 ,this is a curious anomaly1 and cannot be well explained in the present state of our knowledge of stellar systems4 ,in the case of ,greek3 a ,centauri the masses of the components are about equal1 while the primary star is about #c times brighter than the other4 ,but here the discrepancy is satisfactorily explained by the difference in character of the spectra1 the brighter component having a spectrum of the solar type1 while the fainter seems further advanced on the downward road of evolution1 that is1 more consolidated and having1 perhaps1 less intrinsic brightness of surface4 ,in the case of ,sirius and its faint attendant1 the mass of the bright star is about twice the mass of the satellite1 while its light is about #dj1jjj times greater6 ,here the satellite is either a cooled-down sun or perhaps a gaseous nebula4 ,there seems to be no other explanation of this curious paradox4 ,the same remark applies to ,procyon1 where the bright star is about #ajj1jjj times brighter than its faint companion1 although its mass is only #e times greater4 ,the bright star ,capella forms a curious anomaly or paradox4 ,spectroscopic observations show that it is a very close binary pair4 ,it has been seen elongated at the ,greenwich ,observatory with the great #bh-;inch refractor--the work of ,sir ,howard ,grubb--and the spectroscopic and visual measurements agree in indicating that its mass is about #ah times the mass of the sun4 ,but its parallax 7about #jjh7 shows that it is about #abh times brighter than the sun6 ,this great brilliancy is inconsistent with the star's computed mass1 which would indicate a much smaller brightness4 ,the sun placed at the distance of ,capella would1 ,i find1 shine as a star of about #e-a_/b magnitude1 while ,capella is one of the brightest stars in the sky4 ,as the spectrum of ,capella's light closely resembles the solar spectrum1 we seem justified in assuming that the two bodies have pretty much the same physical composition4 ,the discrepancy between the computed and actual brightness of the star cannot be explained satisfactorily1 and the star remains an astronomical enigma4 ,three remarkable double-star systems have been discovered by ,dr4 ,see in the southern hemisphere4 ,the first of these is the bright star ,greek3 a ,phoenicis1 of which the magnitude is #bd1 or only very slightly fainter than the ,pole ,star4 ,it is attended by a faint star of the #acth magnitude at a distance of less than #aj seconds 7#ahig74 ,the bright star is of a deep orange or reddish colour1 and the great difference in brightness between the component stars renders the system both striking and difficult4 ,the second is ,greek3 m ,velorum1 a star of the #crd magnitude1 which has a companion of the #aath magnitude1 and only #b-a_/b from its bright primary 7#ahig74 ,dr4 ,see describes this pair as one of the most extraordinary in the heavens4 ,the third is ,greek3 ,centauri1 of #b-a_/b magnitude1 with a companion of #ac-a_/b magnitude at a distance of #efe 7#ahig72 colours yellow and purple4 ,this pair is extremely difficult1 requiring a powerful telescope to see it4 ,dr4 ,see thinks that these three objects may be regarded as amongst the most splendid in the heavens4 ,the following notes are from ,burnham's recently published ,general ,catalogue of ,double ,stars4 ,the ,pole ,star has a well-known companion of about the #ith magnitude1 which is a favourite object for small telescopes4 ,burnham finds that the bright star and its faint companion are relatively fixed1 and are probably only an optical pair4 ,some other companions have been suspected by amateur observers1 but ,burnham finds that there is nothing nearer than the known companion within the reach of the great #cf-;inch telescope of the ,lick ,observatory 7,cat41 p4 #bii74 ,the well-known companion to the bright star ,rigel 7,greek3 b ,orionis7 has been suspected for many years to be a close double star4 ,burnham concludes that it is really a binary star1 and its period may be shorter than that of any known pair 7,cat41 p4 #daa74 ,burnham finds that the four brighter stars in the trapezium in the great ,orion nebula 7in the sword7 are relatively fixed 7,cat41 p4 #dbf74 ,greek3 g ,leonis4 ,this double star was for many years considered to be a binary1 but ,burnham has shown that all the measures may be satisfactorily represented by a straight line1 and that consequently the pair merely forms an optical double4 #db ,com ,berenices4 ,this is a binary star of which the orbit plane passes nearly through the earth4 ,the period is about #be-a_/b years1 and ,burnham says the orbit is as accurately known as that of any known binary4 ,greek3 s ,coron ,borealis4 ,burnham says that the orbits hitherto computed--with periods ranging from #aie years 7,jacob7 to #hdf years 7,doberck7 are mere guess work1 and it will require the measures of at least another century1 and perhaps a much longer time1 to give an approximate period 7,cat41 p4 #bji74 ,so here is some work left for posterity to do in this field4 #gj ,ophiuchi4 ,with reference to this well-known binary star1 ,burnham says1 the elements of the orbit are very accurately known4 ,the periods computed range from #hfff years 7,doolittle7 to #ihae years 7,powell74 ,the present writer found a period of #hghd years1 which cannot be far from the truth4 ,burnham found #hgge years 7,cat41 p4 #ggd74 ,in this case there is not much left for posterity to accomplish4 #fa ,cygni4 ,with reference to this famous star ,burnham says1 ,so far the relative motion is practically rectilinear4 ,if the companion is moving in a curved path1 it will require the measures of at least another half-century to make this certain4 ,the deviation of the measured positions during the last #gj years from a right line are less than the average errors of the observations4 ,burnham once saw a faint companion to ,sirius of the #afth magnitude1 and measured its position with reference to the bright star 7#bhjf3 #djbe3 #ahiihf74 ,but he afterwards found that it was not a real object but a reflection from ,sirius 7in the eye-piece74 ,such false images are called ghosts4 ,with reference to the well-known double 7or rather quadruple7 star ,greek3 e ,lyr1 near ,vega1 and supposed faint stars near it1 ,burnham says1 ,from time to time various small stars in the vicinity have been mapped1 and much time wasted in looking for and speculating about objects which only exist in the imagination of the observer4 ,he believes that many of these faint stars1 supposed to have been seen by various observers1 are merely ghosts produced by reflection4 ,the binary star ,greek3 z ,botis1 which has long been suspected of small and irregular variation of light1 showed remarkable spectral changes in the year #aije1cai somewhat similar to those of a nova1 or temporary star4 ,it is curious that such changes should occur in a star having an ordinary ,sirian type of spectrum6 ,a curious quadruple system has been discovered by ,mr4 ,r4 ,t4 ,a4 ,innes in the southern hemisphere4 ,the star ,greek3 k ,toucani is a binary star with components of magnitudes #e and #gg1 and a period of revolution of perhaps about #ajjj years4 ,within #f' of this pair is another star 7,lacaille #cec71 which is also a binary1 with a period of perhaps #gb years4 ,both pairs have the same proper motion through space1 and evidently form a vast quadruple system2 for which ,mr4 ,innes finds a possible period of #cjj1jjj years4#cbj ,it is a curious fact that the performance of a really good refracting telescope actually exceeds what theory would indicate6 at least so far as double stars are concerned4 ,for example1 the famous double-star observer ,dawes found that the distance between the components of a double star which can just be divided1 is found by dividing #def by the aperture of the object-glass in inches4 ,now theory gives #eeb divided by the aperture4 ,the actual telescope--if a really good one--thus exceeds its theoretical requirements4 ,the difference between theory and practice in this case seems to be due to the fact that in the 'spurious' star disc shown by good telescopes1 the illumination at the edges of the star disc is very feeble1 so that its full size is not seen except in the case of a very bright star4#cba ,,chapter ,,xvi ,variable ,stars ,in that interesting work ,a ,cycle of ,celestial ,objects1 ,admiral ,smyth says 7p4 #bge71 ,geminiano ,montanari1 as far back as #afgj1 was so struck with the celestial changes1 that he projected a work to be intituled the ,instabilities of the ,firmament1 hoping to show such alterations as would be sufficient to make even ,aristotle--were he alive--reverse his opinion on the incorruptibility of the spangled sky3 ',there are now wanting in the heavens1' said he1 'two stars of the #bnd magnitude in the stem and yard of the ship ,argo4 ,i and others observed them in the year #affd1 upon occasion of the comet that appeared in that year4 ,when they first disappeared ,i know not2 only ,i am sure that on ,april #aj1 #affh1 there was not the least glimpse of them to be seen4' ,smyth adds1 ,startling as this account is--and ,i am even disposed to question the fact--it must be recollected that ,montanari was a man of integrity1 and well versed in the theory and practice of astronomy2 and his account of the wonder will be found--in good set ,latin--in page #bbjb of the ,philosophical ,transactions for #afga4 ,there must be1 ,i think--as ,smyth suggests--some mistake in ,montanari's observations1 for it is quite certain that of the stars mentioned by ,ptolemy 7second century ,a4,d47 there is no star of the #bnd magnitude now missing4 ,it is true that ,al-,sufi 7tenth century7 mentions a star of the third magnitude mentioned by ,ptolemy in the constellation of the ,centaur 7about #b east of the star ,greek3 e ,centauri7 which he could not find4 ,but this has nothing to do with ,montanari's stars4 ,montanari's words are very clear4 ,he says1 ,desunt in ,coelo du stell ,secund ,magnitudinis in ,puppi ,navis ejusve ,transtris ,bayero ,greek3 b et ,greek3 g1 prope ,canem ,majoris1 me et aliis1 occasione prsertim ,comet ,a4 #affd observat et recognit4 ,earum ,disparitionem cui ,anno debeam1 non novi2 hoc indubium1 quod die #aj ,april1 #affh1 ne vestigium quidem illarum adesse amplius observe2 cteris circa eas etium quart et quint magnitudinis1 immotis4 ,so the puzzle remains unsolved4 ,sir ,william ,herschel thought that of all stars which are singly visible1 about one in thirty are undergoing an observable change4#cbb ,now taking the number of stars visible to the naked eye at #fjjj1 this would give about #bjj variable stars visible at maximum to the unaided vision4 ,but this estimate seems too high4 ,taking all the stars visible in the largest telescopes--possibly about #ajj millions--the proportion of variable stars will probably be much smaller still4 ,the theory that the variation of light in the variable stars of the ,algol type is due to a partial eclipse by a companion star 7not necessarily a dark body7 is now well established by the spectroscope1 and is accepted by all astronomers4 ,the late ,miss ,clarke has well said to argue this point would be enforcer une porte ouverte4 ,according to ,dr4 ,a4 ,w4 ,roberts1 the components of the following ,algol variables revolve in contact3 ,v ,puppis1 ,x ,carin1 ,greek3 b ,lyr1 and ,greek3 u ,pegasi4 ,of those ,v ,puppis and ,greek3 b ,lyr are known spectroscopic binaries4 ,the others are beyond the reach of the spectroscope1 owing to their faintness4 ,a very curious variable star of the ,algol type is that known as ,r ,r ,draconis4 ,its normal magnitude is #aj1 but at minimum it becomes invisible in a #g-a_/b-;inch refracting telescope4 ,the variation must1 therefore1 be over #c magnitudes1 that is1 at minimum its light must be reduced to about one-sixteenth of its normal brightness4 ,the period of variation from maximum to minimum is about #bhc days4 ,the variation of light near minimum is extraordinarily rapid1 the light decreasing by about #a magnitude in half an hour4#cbc ,a very remarkable variable star has been recently discovered in the constellation ,auriga4 ,prof4 ,hartwig found it of the #ith magnitude on ,march #f1 #aijh1 the star having increased four magnitudes in one day1 whilst within eight days it was less than the #adth magnitude4#cbd ,in other words its light increased at least one-hundredfold in eight days6 ,the period of the well-known variable star ,greek3 b ,lyr seems to be slowly increasing4 ,this ,dr4 ,roberts 7of ,south ,africa7 considers to be due to the component stars slowly receding from each other4 ,he finds that a very slight increase of one-thousandth part of the radius of the orbit would account for the augmentation in time1 #cjm in a century4 ,according to the theory of stellar evolution the lengthening of the period of revolution of a binary star would be due to the drag caused by the tides formed by each component on the other4#cbe ,m4 ,sebastian ,albrecht finds that in the short-period variable star known as ,t ,vulpecul 7and other variables of this class1 such as ,y ,ophiuchi71 there can be no eclipse to explain the variation of light 7as in the case of ,algol74 ,the star is a spectroscopic binary1 it is true1 but the maximum of light coincides with the greatest velocity of approach in the line of sight1 and the minimum with the greatest velocity of recession4 ,thus the light curve and the spectroscopic velocity curve are very similar in shape1 but one is like the other turned upside down4 ,that is1 the two curves have a very close correspondence in phase in addition to correspondence of shape and period4#cbf ,the star now known as ,w ,urs ,majoris 7the variability of which was discovered by ,mller and ,kempf in #aijb71 and which lies between the stars ,greek3 th and ,greek3 u of that constellation1 has the marvellously short period of #d hours 7from maximum to maximum74 ,messrs4 ,jordan and ,parkhurst 7,u4,s4,a471 find from photographic plates that the star varies from #gbd to #hag magnitude4#cbg ,the light at maximum is1 therefore1 more than double the light at minimum4 ,a sun which loses more than half its light and recovers it again in the short period of #d hours is certainly a curious and wonderful object4 ,in contrast with the above1 the same astronomers have discovered a star in ,perseus which seems to vary from about the #fth to the #gth magnitude in the very long period of #g-a_/b years6 ,it is now known as ,x ,persei1 and its position for #aijj is ,r4,a4 #c;h #dim #hs1 ,dec4 ,n4 #cj #df'1 or about one degree south-east of the star ,greek3 z ,persei4 ,it seems to be a variable of the ,algol type1 as the star remained constant in light at about the #fth magnitude from #ahhg to #ahia4 ,it then began to fade1 and on ,december #a1 #ahig1 it was reduced to about the #gth magnitude4 ,on the night of ,august #bj1 #ahhf1 ,prof4 ,colbert1 of ,chicago1 noticed that the star ,greek3 z ,cassiopei increased in brightness by quite half a magnitude1 and about half an hour afterwards began to return to its normal magnitude4#cbh ,this curious outburst of light in a star usually constant in brightness is 7if true7 a very unusual phenomenon4 ,but a somewhat similar fluctuation of light is recorded by the famous ,german astronomer ,heis4 ,on ,september #bf1 #ahej1 he noted that the star ,greek3 z ,lyr became1 for a moment1 very bright1 and then again faint4 7,the words in his original observing book are3 ,greek3 z ,lyr wurde einen ,moment sehr hell und hierauf wieder dunkel47 ,as ,heis was a remarkably accurate observer of star brightness1 the above remark deserves the highest confidence4#cbi ,the variable star known as the ,v ,delphini was found to be invisible in the great #dj-;inch telescope of the ,yerkes ,observatory on ,july #bj1 #aijj4 ,its magnitude was1 therefore1 below the #agth4 ,at its maximum brightness it is about #g-a_/b1 or easily visible in an ordinary opera-glass1 so that its range of variation is nearly1 or quite1 ten magnitudes4 ,that is1 its light at maximum is about #aj1jjj times its light at minimum4 ,that a sun should vary in light to this enormous extent is certainly a wonderful fact4 ,a variable discovered by ,ceraski 7and numbered #gegi in ,chandlers' ,catalogue7 had passed below the limit of the #dj-;inch in ,june1 #aijj1 and was1 therefore1 not brighter than #ag mag4#ccj ,the late ,sir ,c4 ,e4 ,peck and his assistant1 ,mr4 ,grover1 made many valuable observations of variable stars at the ,rousden ,observatory during many years past4 ,among other interesting things noted1 ,peck sometimes saw faint stars in the field of view of his telescope which were at other times invisible for many months1 and he suggested that these are faint variable stars with a range of brightness from the #acth to the #bjth magnitude4 ,he adds1 ,here there is a practically unemployed field for the largest telescopes4 ,considering the enormous number of faint stars visible on stellar photographs the number of undiscovered variable stars must be very large4 ,admiral ,smyth describes a small star near ,greek3 b ,leonis1 about #e' distant1 of about #hth magnitude1 and dull red4 ,in #ahfd ,mr4 ,knott measured a faint star close to ,smyth's position1 but estimated it only #aaf magnitude4 ,the ,admiral's star would thereupon seem to be variable4#cca ,the famous variable star ,greek3 ,argus1 which ,sir ,john ,herschel1 when at the ,cape of ,good ,hope in #ahch1 saw involved in dense nebulosity1 was in ,april1 #ahfi1 seen on the bare sky1 with the great ,melbourne telescope1 the nebula having disappeared for some distance round it4 ,other changes were noticed in this remarkable nebula4 ,the ,melbourne observers saw three times as many stars as were seen by ,herschel4 ,but of course their telescope is much larger--#dh inches aperture1 compared with ,herschel's #bj inches4 ,prof4 ,e4 ,c4 ,pickering thinks that the fluctuations of light of the well-known variable star ,r ,coron 7in the ,northern ,crown71 are unlike those of any known variable4 ,this very curious object--one of the most curious in the heavens--sometimes remains for many months almost constant in brightness 7just visible to the naked eye71 and then rapidly fades in light by several magnitudes6 ,thus its changes of light in ,april and ,may1 #aije1 were as follows3-- #aije1 ,april #a #fj magnitude #aa #gc #ab #hd ,may #a #aad #g #abe ,thus between ,april #a and ,may #a1 its light was reduced by over #e magnitudes4 ,in other words1 the light of the star on ,may #a was reduced to less than one-hundredth of its light on ,april #a4 ,if our sun were to behave in this way nearly all life would soon be destroyed on the face of the earth4 ,m4 ,h4 ,e4 ,lau finds that the short-period variable star ,greek3 d ,cephei varies slightly in colour as well as in light1 and that the colour curve is parallel to the light curve4 ,near the minimum of light the colour is reddish yellow1 almost as red as ,greek3 z ,cephei2 a day later it is pure yellow1 and of about the same colour as the neighbouring ,greek3 e ,cephei4#ccb ,but it would not be easy to fully establish such slight variations of tint4 ,a remarkably bright maximum of the famous variable ,mira ,ceti occurred in #aijf4 ,in ,december of that year it was fully #bnd magnitude4 ,the present writer estimated it #ah1 or nearly equal to the brightest on record--#ag observed by ,sir ,william ,herschel and ,wargentin in the year #aggi4 ,from photographs of the spectrum taken by ,mr4 ,slipher at the ,lowell ,observatory in #aijg1 he finds strong indications of the presence of the rather rare element vanadium in the star's surroundings4 ,prof4 ,campbell finds with the ,mills spectrograph attached to the great #cf-;inch telescope of the ,lick ,observatory that ,mira is receding from the earth at the apparently constant velocity of about #ch miles a second4#ccc ,this1 of course1 has nothing to do with the variation in the star's light4 ,prof4 ,campbell failed to see any trace of the green line of hydrogen in the star's spectrum1 while two other lines of the hydrogen series glowed with singular intensity4 ,mr4 ,newall has found evidence of the element titanium in the spectrum of ,betelgeuse 7,greek3 a ,orionis72 ,mr4 ,goatcher and ,mr4 ,lunt 7of the ,cape ,observatory7 find tin in ,antares 7and ,scorpii74 ,if the latter observation is confirmed it will be the first time this metal has been found in a star's atmosphere4#ccd ,it is a curious fact that ,al-,sufi 7tenth century7 does not mention the star ,greek3 e ,aquil1 which lies closely north-west of ,greek3 z ,aquil1 as it is now quite conspicuous to the naked eye4 ,it was suspected of variation by ,sir ,william ,herschel4 ,it was first recorded by ,tycho ,brah about #aeij1 and he called it #crd magnitude4 ,bayer also rated it #c1 and since his time it has been variously estimated from #c-a_/b to #d4 ,if it was anything like its present brightness 7#dba ,harvard7 in the tenth century it seems difficult to explain how it could have escaped ,al-,sufi's careful scrutiny of the heavens1 unless it is variable4 ,its colour seems reddish to me4 ,mr4 ,w4 ,t4 ,lynn has shown--and ,i think conclusively--that the so-called new star of ,a4,d4 #chi 7which is said to have appeared near ,altair in the ,eagle7 was really a comet4#cce ,near the place of ,tycho ,brah's great new star of #aegb 7the ,pilgrim ,star71 ,hind and ,w4 ,e4 ,plummer observed a small star 7,no4 #abi of d',arrest's catalogue of the region7 which seemed to show small fluctuations of light1 which scarcely include a whole magnitude4 ,this may possibly be identical with ,tycho ,brah's wonderful star1 and should be watched by observers4 ,the place of this small star is 7for #ahfe7 ,r4,a4 #j;h #agm #ahs1 ,n4,p4,d4 #bf #cg'a4 ,the region was examined by ,prof4 ,burnham in #ahij with the #cf-;inch telescope of the ,lick ,observatory4 ,none of the faint stars near the place presented any peculiarity worthy of remark1 but three double stars were found4#ccf ,with reference to the famous ,nova 7,t7 ,coron--the ,blaze ,star of #ahff--,prof4 ,barnard finds from careful comparisons with small stars in its vicinity that the ,nova is now essentially of the same brightness it was before the outburst of #ahff 444 there seems to be no indication of motion in the ,nova4 ,with reference to the cause of temporary stars1 or nov1 as they are now called by astronomers--the late ,prof4 ,h4 ,c4 ,vogel said-- ,a direct collision of two celestial bodies is not regarded by ,huggins as an admissible explanation of the ,nova2 a partial collision has little probability1 and the most that can be admitted is perhaps the mutual penetration and admixture of the outer gaseous envelopes of the two bodies at the time of their closest approach4 ,a more probable explanation is given by an hypothesis which we owe to ,klinkerfues1 and which has more recently been further developed by ,wilsing1 viz4 that by the very close passage of two celestial bodies enormous tidal disturbances are produced and thereby changes in the brightness of the bodies4 ,in the case of the two bodies which form the ,nova1 it must be assumed that these phenomena are displayed in the highest degree of development1 and that changes of pressure have been produced which have caused enormous eruptions from the heated interior of the bodies2 the eruptions are perhaps accompanied by electrical actions1 and are comparable with the outbursts in our own sun1 although they are on a much larger scale4#ccg ,it will be noticed that this hypothesis agrees with the fundamental assumption of the ,planetesimal ,hypothesis advocated by ,professors ,chamberlin and ,moulton 7see my ,astronomical ,essays1 p4 #cbd74 ,the rush of a comparatively small body through a mass of gaseous matter seems also a very plausible hypothesis4 ,this idea was originally advanced by ,prof4 ,seeliger1 and independently by ,mr4 ,monck4 ,with reference to the nebula which was observed round the great new star of #aija--,nova ,persei--,prof4 ,lewis ,bell supports the theory of ,seeliger1 which accounts for the apparent movements of the brightest portions of the nebula by supposing that the various parts of the highly tenuous matter were successively lighted up by the effects of a travelling electro-magnetic wavefront1 and he shows that this theory agrees well with the observed phenomenon4#cch ,the collision theory which explained the sudden outburst of light by the meeting of two dark bodies in space1 seems to be now abandoned by the best astronomers4 ,the rapid cooling down of the supposed bodies indicated by the rapid decrease of light is quite inconsistent with this hypothesis4 ,the rapid diminution in the light of some of these new stars is very remarkable4 ,thus the new star which suddenly blazed out near the nucleus of the great nebula in ,andromeda in ,august1 #ahhe1 faded down in #e months from the limit of visibility to the naked eye to that of a #bf-;inch telescope6 ,a large body could not cool in this way4 ,mr4 ,harold ,k4 ,palmer thinks that the complete and astonishingly rapid changes of spectral type observed in the case of ,nova ,cygni and ,nova ,aurig1 and likewise those observed in ,nova ,norm1 ,nova ,sagittarii and ,nova ,persei1 leave little doubt that the masses of these objects are small4#cci ,no less than #cgdh variable stars had been discovered up to ,may1 #aijg4 ,of these #biji were found at ,harvard ,observatory 7,u4,s4,a47 chiefly by means of photography4#cdj ,the star #ad4 #aijd ,cygni has a period of only #c hours #ad minutes1 which is the shortest period known for a variable star4 ,a very interesting discovery has recently been made with reference to the star ,greek3 m ,herculis4 ,it has been long suspected of variable light with a period of #ce or #dj days1 or perhaps irregular4 ,frost and ,adams now find it to be a spectroscopic binary1 and further observations at ,harvard ,observatory show that it is a variable of the ,algol 7or perhaps ,greek3 b ,lyr7 type4 ,the ,algol variation of light was suggested by ,,mm4 ,baker and ,schlesinger4 ,the period seems to be about #bje days4#cda ,the northern of the two pointers in the ,plough 7so called because they nearly point to the ,pole ,star7 is about the #bnd magnitude1 as ,al-,sufi rated it4 ,it was thought to be variable in colour by ,klein1 ,konkoly1 and ,weber2 and ,m4 ,lau has recently found a period of #ej days with a maximum of jaune rougetre on ,april #b1 #aijb4 ,the famous variable star ,greek3 ,argus did not exceed the #hth magnitude in ,february1 #aijg1 according to ,mr4 ,tebbutt4#cdb ,this is the faintest ever recorded for this wonderful star4 ,it is stated in ,knowledge 7vol4 #e1 p4 #c1 ,january #d1 #ahhd7 that the temporary star of #ahgf 7in the constellation of ,cygnus7 had long been known and catalogued as a telescopic star of the #ith magnitude with nothing to distinguish it from the common herd4 ,but this is quite erroneous4 ,the star was quite unknown before it was discovered by ,schmidt at ,athens on ,november #bd of that year4 ,the remark apparently refers to the ,blaze ,star of #ahff in ,corona ,borealis1 which was known previously as a star of about the #ith magnitude before its sudden outburst on ,may #ab of that year4 ,this new star of #ahff--,t ,coron1 as it is now called--was1 with the possible exception of ,nova ,persei 7#aija71 the only example of a nova which was known to astronomers as a small star previous to the great outburst of light4 ,it is the brightest of the nov still visible4 ,it was the first of these interesting objects to be examined with the spectroscope4 ,it was observed by ,burnham in the years #aijd-aijf with the great #dj-;inch telescope of the ,yerkes ,observatory 7,u4,s4,a474 ,he found its colour white1 or only slightly tinged with yellow4 ,in ,august and ,september1 #aijf1 he estimated its magnitude at about #ic1 and it would seem therefore that the ,nova is now essentially of the same brightness it was before the outburst in #ahff4 ,it shows no indication of motion4 ,burnham found no peculiarity about its telescopic image4 ,a small and very faint nebula was found by ,burnham a little following 7that is east of7 the nova4#cdc ,the following details of the great new star of #aegb--the ,pilgrim ,star of ,tycho ,brah--are given by ,delambre4#cdd ,in ,november1 #aegb1 it was brighter than ,sirius1 ,vega1 and ,jupiter1 and almost equal to ,venus at its brightest4 ,during ,december it resembled ,jupiter in brightness4 ,in ,january1 #aegc1 it was fainter and only a little brighter than stars of the #ast magnitude4 ,in ,february and ,march it was equal to #ast magnitude stars1 and in ,april and ,may was reduced to the #bnd magnitude4 ,in ,june and ,july it was #crd magnitude2 in ,september of the #dth1 and at the end of #aegc it was reduced to the #eth magnitude4 ,in ,february1 #aegd1 it was #fth magnitude1 and in ,march of the same year it became invisible to the naked eye4 ,from this account it will be seen that the decrease in light of this curious object was much slower than that of ,nova ,persei 7#aija7 7the new star of the new century74 ,this would suggest that it was a much larger body4 ,there were also changes in its colour4 ,when it was of the brightness of ,venus or ,jupiter it shone with a white light4 ,it then became golden1 and afterwards reddish like ,mars1 ,aldebaran1 or ,betelgeuse4 ,it afterwards became of a livid white colour like ,saturn1 and this it retained as long as it was visible4 ,tycho ,brah thought that its apparent diameter might have been about #c-a_/b minutes of arc1 and that it was possibly #cfa times smaller than the earth767 ,but we now know that these estimates were probably quite erroneous4 ,temporary stars were called by the ancient ,chinese ,ke-sing1 or guest stars4#cde ,a temporary star recorded by ,ma-tuan-lin 7,chinese ,annals7 in ,february1 #aegh1 is described as a star as large as the sun4 ,but its position is not given4#cdf ,about the middle of ,september1 #ahgh1 ,mr4 ,greely1 of ,boston 7,u4,s4,a471 reported to ,mr4 ,e4 ,f4 ,sawyer 7the eminent observer of variable stars7 that1 about the middle of ,august of that year1 he had seen the famous variable star ,mira ,ceti of about the #bnd magnitude1 although the star did not attain its usual maximum until early in ,october1 #ahgh4 ,mr4 ,greely stated that several nights after he first saw ,mira it had faded to the #dth or #eth magnitude4 ,if there was no mistake in this observation 7and ,sawyer could find none7 it was quite an unique phenomenon1 as nothing of the sort has been observed before or since in the history of this famous star4 ,it looks as if ,mr4 ,greely had observed a new or temporary star near the place of ,mira ,ceti2 but as the spot is far from the ,milky ,way1 which is the usual seat of such phenomena1 this hypothesis seems improbable4 ,in the so-called ,cepheid and ,geminid variables of short period1 the principal characteristics of the light variation are as follows3-- #a4 ,the light varies without pause4 #b4 ,the amount of their light variation is usually about #a magnitude4 #c4 ,their periods are short--a few days only4 #d4 ,they are of a spectral type approximately solar2 no ,orion1 ,sirian or ,arcturian stars having been found among them4 #e4 ,they seem to be found in greater numbers in certain parts of the sky1 notably in the ,milky ,way1 but exhibit no tendency to form clusters4 #f4 ,all those stars whose radial velocities have been studied have been found to be binaries whose period of orbital revolution coincides with that of their light change4 #g4 ,the orbits1 so far as determined1 are all small1 a sin i being #b1jjj1jjj kilometres or less4 #h4 ,their maximum light synchronizes with their maximum velocity of approach1 and minimum light with maximum velocity of recession4 #i4 ,no case has been found in which the spectrum of more than one component has been bright enough to be recorded in the spectrograms4#cdg ,it is very difficult to find an hypothesis which will explain satisfactorily all these characteristics1 and attempts in this direction have not proved very successful4 ,mr4 ,j4 ,c4 ,duncan suggests the action of an absorbing atmosphere surrounding the component stars4 ,on ,march #cj1 #afab1 ,scheiner saw a star near ,jupiter4 ,it was at first equal in brightness to ,jupiter's satellites4 ,it gradually faded1 and on ,april #h of the same year it was only seen with much difficulty in a very clear sky4 ,after that date it was never seen again1 although carefully looked for under favourable conditions4 ,an attempted identification of ,scheiner's star was made in recent years by ,winnecke4 ,he found that its position1 as indicated by ,scheiner1 agrees with that of the ,bonn ,durchmusterung star #ae1 #bjhc 7#h-a_/b magnitude74 ,this star is not a known variable4 ,winnecke watched it for #ag years1 but found no variation of light4 ,from ,scheiner's recorded observations his star seems to have reached the #fth magnitude1 which is considerably brighter than the ,durchmusterung star watched by ,winnecke4#cdh ,with reference to the colours of the stars1 the supposed change of colour in ,sirius from red to white is well known1 and will be considered in the chapter on the ,constellations4 ,the bright star ,arcturus has also been suspected of variation in colour4 ,about the middle of the nineteenth century ,dr4 ,julius ,schmidt1 of ,athens1 the well-known observer of variable stars1 thought it one of the reddest stars in the sky1 especially in the year #ahda1 when he found its colour comparable with that of the planet ,mars4#cdi ,in #aheb1 however1 he was surprised to find it yellow and devoid of any reddish tinge2 in colour it was lighter than that of ,capella4 ,in #ahfc1 ,mr4 ,jacob ,ennis found it decidedly orange4 ,ptolemy and ,al-,sufi called it red4 ,mr4 ,ennis speaks of ,capella as blue 7classing it with ,rigel71 and comparing its colour with that of ,vega6#cej ,but the present writer has never seen it of this colour4 ,to his eye it seems yellowish or orange4 ,it was called red by ,ptolemy1 ,el ,fergani1 and ,riccioli2 but ,al-,sufi says nothing about its colour4 ,of ,greek3 b ,urs ,minoris1 ,heis1 the eminent ,german astronomer said1 ,i have had frequent opportunities of convincing myself that the colour of this star is not always equally red2 at times it is more or less yellow1 at others most decidedly red4#cea ,among double stars there are many cases in which variation of colour has been suspected4 ,in some of these the difference in the recorded colour may possibly be due to colour blindness in some of the observers2 but in others there seems to be good evidence in favour of a change4 ,the following may be mentioned3-- ,greek3 ,cassiopei4 ,magnitudes of the components about #d and #g-a_/b4 ,recorded as red and green by ,sir ,john ,herschel and ,south2 but yellow and orange by ,sestini4 ,greek3 i ,trianguli4 ,magnitudes #e-a_/b and #g4 ,secchi estimated them as white or yellow and blue2 but ,webb called them yellow and green 7#ahfb74 ,greek3 g ,leonis1 #b and #c-a_/b4 ,sir ,william ,herschel noted them white and reddish white2 but ,webb1 light orange and greenish yellow4 #ab ,canum ,venaticorum1 #b-a_/b and #f-a_/b4 ,white and red1 ,sir ,william ,herschel2 but ,sir ,john ,herschel says in #ahcj1 ,with all attention ,i could perceive no contrast of colours in the two stars4 ,struve found them both white in #ahcj1 thus agreeing with ,sir ,john ,herschel4 ,sestini saw them yellow and blue in #ahdd2 ,smyth1 in #ahee1 pale reddish white and lilac2 ,dembowski1 in #ahef1 white and pale olive blue2 and ,webb1 in #ahfb1 flushed white and pale lilac4 ,on ,october #ac1 #aijg1 ,nova ,persei1 the great new star of #aija1 was estimated to be only #aadd magnitude1 or about #aa-a_/b4 ,when at its brightest this famous star was about zero magnitude2 so that it has in about #f years faded about #aa-a_/b magnitudes in brightness2 in other words1 it has been reduced to #a_/djjjj of its greatest brilliancy6 ,,chapter ,,xvii ,nebul and ,clusters ,in his interesting and valuable work on ,the ,stars1 the late ,prof4 ,newcomb said-- ,great numbers of the nebul are therefore thousands of times the dimensions of the earth's orbit1 and most of them are thousands of times the dimensions of the whole solar system4 ,that they should be completely transparent through such enormous dimensions shows their extreme tenuity4 ,were our solar system placed in the midst of one of them it is probable that we should not be able to find any evidence of its existence6 ,prof4 ,perrine thinks that the total number of the nebul will ultimately be found to exceed a million4#ceb ,dr4 ,max ,wolf has discovered a number of small nebul in the regions near ,algol and ,nova ,persei 7the great new star of #aija74 ,he says1 ,they mostly lie in two bands1 and are especially numerous where the two bands meet1 a region of #ab minutes of arc square containing no less than #adh of them4 ,they are usually round with central condensation1 and form of ,andromeda nebula4#cec ,some small nebul have been found in the vicinity of the globular clusters4 ,they are described by ,prof4 ,perrine as very small and like an out of focus image of a small star4 ,they appear to be most numerous about clusters which are farthest from the galaxy4 ,prof4 ,perrine says1 ,practically all the small nebul about the globular clusters are elliptical or circular4 ,those large enough to show structure are spirals4 ,doubtless the majority of these are spirals4#ced ,this seems further evidence in favour of the spiral nebular hypothesis of ,chamberlin and ,moulton4 ,a great photographic nebula in ,orion was discovered by ,prof4 ,barnard in #ahid4 ,in a drawing he gives of the nebula1#cee it forms a long streak beginning a little south of ,greek3 g ,orionis 7,bellatrix71 passing through the star #ch ,orionis north of #ea and south of #ef and #fj ,orionis4 ,then turning south it sweeps round a little north of ,greek3 k ,orionis2 then over #bi ,orionis1 and ends a little to the west of ,greek3 ,orionis4 ,there is an outside patch west of ,rigel4 ,barnard thinks that the whole forms a vast spiral structure2 probably connected with the great nebula in the sword of ,orion1 which it surrounds4 ,from calculations of the brightness of surface 7intrinsic brightness7 of several planetary nebul made by the present writer in the year #aije1 he finds that the luminosity is very small compared with that of the moon4 ,the brightest of those examined 7h #ccfe1 in the southern hemisphere1 near the ,southern ,cross7 has a surface luminosity of only #a_/djj of that of the moon4#cef ,the great nebul in ,orion and ,andromeda seem to have still smaller intrinsic brightness4 ,arago says-- ,the spaces which precede or which follow simple nebul1 and a fortiori groups of nebul1 contain generally few stars4 ,herschel found this rule to be invariable4 ,thus every time that1 during a short interval1 no star appeared1 in virtue of the diurnal motion1 to place itself in the field of his motionless telescope1 he was accustomed to say to the secretary who assisted him 7,miss ,caroline ,herschel71 ',prepare to write2 nebul are about to arrive4'#ceg ,commenting on this remark of ,arago1 the late ,herbert ,spencer says-- ,how does this fact consist with the hypothesis that nebul are remote galaxies8 ,if there were but one nebula1 it would be a curious coincidence were this one nebula so placed in the distant regions of space as to agree in direction with a starless spot in our sidereal system6 ,if there were but two nebul1 and both were so placed1 the coincidence would be excessively strange4 ,what shall we say on finding that they are habitually so placed8 7the last five words replace some that are possibly a little too strong74444 ,when to the fact that the general mass of nebul are antithetical in position to the general mass of the stars1 we add the fact that local regions of nebul are regions where stars are scarce1 and the further fact that single nebul are habitually found in comparatively starless spots1 does not the proof of a physical connection become overwhelming8#ceh ,with reference to the small elongated nebula discovered by ,miss ,caroline ,herschel in #aghc near the great nebula in ,andromeda1 ,admiral ,smyth says1 ,it lies between two sets of stars1 consisting of four each1 and each disposed like the figure #g1 the preceding group being the smallest4#cei ,speaking of the nebula ,messier #c--;a globular cluster in ,canes ,venatici--,admiral ,smyth says1 ,this mass is one of those balls of compact and wedged stars whose laws of aggregation it is so impossible to assign2 but the rotundity of the figure gives full indication of some general attractive bond of union4#cfj ,the terms compact and wedged are1 however1 too strong1 for we know that in the globular clusters the component stars must be separated from each other by millions of miles6 ,prof4 ,chamberlin suggests that the secondary nebula 7as it is called7 in the great spiral in ,canes ,venatici 7,messier #ea7 may possibly represent the body which collided with the other 7the chief nucleus7 in a grazing collision1 and is now escaping4 ,he considers this secondary body to have been a dead sun--that is1 a dark body4#cfa ,this would be very interesting if it could be proved4 ,but it seems to me more probable that the secondary nucleus is simply a larger portion of the ejected matter1 which is now being gradually detached from the parent mass4 ,scheiner says the previous suspicion that the spiral nebul are star clusters is now raised to a certainty1 and that the spectrum of the ,andromeda nebula is very similar to that of the sun4 ,he says there is a surprising agreement of the two1 even in respect to the relative intensity of the separate spectral regions4#cfb ,in the dynamical theory of spiral nebul1 ,dr4 ,e4 ,j4 ,wilczynski thinks that the age of a spiral nebula may be indicated by the number of its coils2 those having the largest number of coils being the oldest1 from the point of view of evolution4#cfc ,this seems to be very probable4 ,in the spectrum of the gaseous nebul1 the ,f line of hydrogen 7,h,greek3 b7 is visible1 but not the ,c line 7,h,greek3 a74 ,the invisibility of the ,c line is explained by ,scheiner as due to a physiological cause1 the eye being less sensitive to that part of the spectrum in which the line appears than to the part containing the ,f line4#cfd ,an apparent paradox is found in the case of the gaseous nebul4 ,the undefined outlines of these objects render any attempt at measuring their parallax very difficult1 if not impossible4 ,their distance from the earth is therefore unknown1 and perhaps likely to remain so for many years to come4 ,it is possible that they may not be farther from us than some of the stars visible in their vicinity4 ,on the other hand1 they may lie far beyond them in space4 ,but whatever their distance from the earth may be1 it may be easily shown that their attraction on the sun is directly proportioned to their distance--that is1 the greater their distance1 the greater the attraction6 ,this is evidently a paradox1 and rather a startling one too4 ,but it is nevertheless mathematically true1 and can be easily proved4 ,for1 their distance being unknown1 they may be of any dimensions4 ,they might be comparatively small bodies relatively near the earth1 or they may be immense masses at a vast distance from us4 ,the latter is1 of course1 the more probable4 ,in either case the apparent size would be the same4 ,take the case of any round gaseous nebula4 ,assuming it to be of a globular form1 its real diameter will depend on its distance from the earth--the greater the distance1 the greater the diameter4 ,now1 as the volumes of spheres vary as the cubes of their diameters1 it follows that the volume of the nebula will vary as the cube of its distance from the earth4 ,as the mass of an attracting body depends on its volume and density1 its real mass will depend on the cube of its distance1 the density 7although unknown7 being a fixed quantity4 ,if at a certain distance its mass is m1 at double the distance 7the apparent diameter being the same7 it would have a mass of eight times m 7#h being the cube of #b71 and at treble the distance its mass would be #bg m1 and so on1 its apparent size being known1 but not its real size4 ,this is obvious4 ,now1 the attractive power of a body varies directly as its mass--the greater the mass1 the greater the attraction4 ,again1 the attraction varies inversely as the square of the distance1 according to the well-known law of ,newton4 ,hence if d be the unknown distance of the nebula1 we have its attractive power varying as d#c divided by d#b1 or directly as the distance d4 ,we have then the curious paradox that for a nebula whose distance from the earth is unknown1 its attractive power on the sun 7or earth7 will vary directly as the distance--the greater the distance the greater the attraction1 and1 of course1 conversely1 the smaller the distance the less the attractive power4 ,this result seems at first sight absurd and incredible1 but a little consideration will show that it is quite correct4 ,consider a small wisp of cloud in our atmosphere4 ,its mass is almost infinitesimal and its attractive power on the earth practically nil4 ,but a gaseous nebula having the same apparent size would have an enormous volume1 and1 although probably formed of very tenuous gas1 its mass would be very great1 and its attractive power considerable4 ,the large apparent size of the ,orion nebula shows that its volume is probably enormous1 and as its attraction on the sun is not appreciable1 its density must be excessively small1 less than the density of the air remaining in the receiver of the best air-pump after the air has been exhausted4 ,how such a tenuous gas can shine as it does forms another paradox4 ,its light is possibly due to some phosphorescent or electrical action4 ,the apparent size of the great nebula in ,andromeda shows that it must be an object of vast dimensions4 ,the nearest star to the earth1 ,alpha ,centauri1 although probably equal to our sun in volume1 certainly does not exceed one-hundredth of a second in diameter as seen from the earth4 ,but in the case of the ,andromeda nebula we have an object of considerable apparent size1 not measured by seconds of arc1 but showing an area about three times greater than that of the full moon4 ,the nebula certainly lies in the region of the stars--much farther off than ,alpha ,centauri--and its great apparent size shows that it must be of stupendous dimensions4 ,a moment's consideration will show that whatever its distance may be1 the farther it is from the earth the larger it must be in actual size4 ,the sun is vastly larger than the moon1 but its apparent size is about the same owing to its greater distance4 ,sir ,william ,herschel thought the ,andromeda nebula to be undoubtedly the nearest of all the great nebul1 and he estimated its distance at #bjjj times the distance of ,sirius4 ,this would not1 however1 indicate a relatively near object1 as it would imply a light journey of over #ag1jjj years6 7,the distance of ,sirius is about #hh light years47 ,it has been generally supposed that this great nebula lies at a vast distance from the earth1 possibly far beyond most of the stars seen in the same region of the sky2 but perhaps not quite so far as ,herschel's estimate would imply4 ,recently1 however1 ,prof4 ,bohlin of ,stockholm has found from three series of measures made in recent years a parallax of #jag4cfe ,this indicates a distance of #a1bac1ccj times the sun's distance from the earth1 and a light journey of about #ai years4 ,this would make the distance of the nebula more than twice the distance of ,sirius1 about four times the distance of ,greek3 a ,centauri1 but less than that of ,capella4 ,prof4 ,bohlin's result is rather unexpected1 and will require confirmation before it can be accepted4 ,but it will be interesting to inquire what this parallax implies as to the real dimensions and probable mass of this vast nebula4 ,the extreme length of the nebula may be taken to represent its diameter considered as circular4 ,for1 although a circle seen obliquely is always foreshortened into an ellipse1 still the longer axis of the ellipse will always represent the real diameter of the circle4 ,this may be seen by holding a penny at various angles to the eye4 ,now1 ,dr4 ,roberts found that the apparent length of the ,andromeda nebula is #b-a_/c degrees1 or #hdjj seconds of arc4 ,the diameter in seconds divided by the parallax will give the real diameter of the nebula in terms of the sun's distance from the earth taken as unity4 ,now1 #hdjj divided by #jag gives nearly #ej1jjj1 that is1 the real diameter of the ,andromeda nebula would be--on ,bohlin's parallax--nearly #ej1jjj times the sun's distance from the earth4 ,as light takes about #ejj seconds to come from the sun to the earth1 the above figures imply that light would take about #bij days1 or over #i months to cross the diameter of this vast nebula4 ,elementary geometrical considerations will show that if the ,andromeda nebula lies at a greater distance from the earth than that indicated by ,bohlin's parallax1 its real diameter1 and therefore its volume and mass1 will be greater4 ,if1 therefore1 we assume the parallax found by ,bohlin1 we shall probably find a minimum value for the size and mass of this marvellous object4 ,among ,dr4 ,roberts' photographs of spiral nebul 7and the ,andromeda nebula is undoubtedly a spiral7 there are some which are apparently seen nearly edgeways1 and show that these nebul are very thin in proportion to their diameter4 ,from a consideration of these photographs we may1 ,i think1 assume a thickness of about one-hundredth of the diameter4 ,this would give a thickness for the ,andromeda nebul of about #ejj times the sun's distance from the earth4 ,this great thickness will give some idea of the vast proportions of the object we are dealing with4 ,the size of the whole solar system--large as it is--is small in comparison4 ,the diameter and thickness found above can easily be converted into miles1 and from these dimensions the actual volume of the nebula can be compared with that of the sun4 ,it is merely a question of simple mensuration1 and no problem of high mathematics is involved4 ,making the necessary calculations1 ,i find that the volume of the ,andromeda nebula would be about #bcb trillion times 7#bcb #ajah7 the sun's volume6 ,now1 assuming that the nebulous matter fills only one-half of the apparent volume of the nebula 7allowing for spaces between the spiral branches71 we have the volume #aaf #ajah4 ,if the nebula had the same density as the sun1 this would be its mass in terms of the sun's mass taken as unity1 a mass probably exceeding the combined mass of all the stars visible in the largest telescopes6 ,but this assumption is1 of course1 inadmissible1 as the sun is evidently quite opaque1 whereas the nebula is1 partially at least1 more or less transparent4 ,let us suppose that the nebula has a mean density equal to that of atmospheric air4 ,as water is about #ggc times heavier than air1 and the sun's density is #ad 7water #a7 we have the mass of the nebula equal to #aaf #ajah divided by #ggc #ad1 or about #ajae times the sun's mass1 which is still much greater than the probable combined mass of all the visible stars4 ,as it seems unreasonable to suppose that the mass of an individual member of our sidereal system should exceed the combined mass of the remainder of the system1 we seem compelled to further reduce the density of the ,andromeda nebula4 ,let us assume a mean density of1 say1 a millionth of hydrogen gas 7a sufficiently low estimate7 which is about #addd times lighter than air1 and we obtain a mass of about #h #ajg or #hj million times the mass of the sun1 which is still an enormous mass4 ,as possibly ,i may have assumed too great a thickness for the nebula1 let us take a thickness of one-tenth of that used above1 or one thousandth of the length of the nebula4 ,this gives a mass of #h million times the sun's mass4 ,this seems a more probable mass if the nebula is--as ,bohlin's parallax implies--a member of our sidereal system4 ,if we assume a parallax of say #jja--or one-hundredth of a second of arc--which would still keep the nebula within the bounds of our sidereal system--we have the dimensions of the nebula increased #ag times1 and hence its mass nearly #ejjj times greater 7#agc7 than that found above4 ,the mass would then be #dj1jjj million times the sun's mass6 ,this result seems highly improbable1 for even this small parallax would imply a light journey of only #cbf years1 whereas the distance of the ,milky ,way has been estimated by ,prof4 ,newcomb at about #cjjj years' journey for light4 ,in ,dr4 ,roberts' photograph many small stars are seen scattered over the surface of the nebula2 but these do not seem to be quite so numerous as in the surrounding sky4 ,if the nebula lies nearer to us than the fainter stars visible on the photograph1 some of them may be obscured by the denser portions of the nebula2 some may be visible through the openings between the spiral branches2 while others may be nearer to us and simply projected on the nebula4 ,to add to the difficulty of solving this celestial problem1 the spectroscope shows that the ,andromeda nebula is not gaseous4 ,the spectrum is1 according to ,scheiner1 very similar to that of the sun1 and there is a surprising agreement of the two1 even in respect to the relative intensities of the separate spectral regions4#cff ,he thinks that the greater part of the stars comprising the nucleus of the nebula belong to the second spectral class 7solar71 and that the nebula is now in an advanced stage of development4 ,no trace of bright nebular lines are present1 so that the interstellar space in the ,andromeda nebula1 just as in our stellar system1 is not appreciably occupied by gaseous matter4#cff ,he suggests that the inner part of the nebula the nucleus corresponds to the complex of those stars which do not belong to the ,milky ,way1 while the latter corresponds to the spirals of the ,andromeda nebula4#cff ,on this view of the matter we may suppose that the component particles are small bodies widely separated1 and in this way the mean density of the ,andromeda nebula may be very small indeed4 ,they cannot be large bodies1 as the largest telescopes have failed to resolve the nebula into stars1 and photographs show no sign of resolution4 ,it has often been suggested1 and sometimes definitely stated1 that the ,andromeda nebula may possibly be an external universe1 that is an universe entirely outside our sidereal system1 and comparable with it in size4 ,let us examine the probability of such hypothesis4 ,assuming that the nebula has the same diameter as the ,milky ,way1 or about #fjjj light years1 as estimated by ,prof4 ,newcomb1 ,i find that its distance from the earth would be about #aej1jjj light years4 ,as this is about #hjjj times the distance indicated by ,bohlin's parallax1 its dimensions would be #hjjj times as great1 and hence its volume and mass would be #hjjj cubed1 or #eab1jjj1jjj1jjj times greater than that found above4 ,that is1 about #d trillion 7#d #ajah7 times the sun's mass6 ,as this appears an incredibly large mass to be compressed into a volume even so large as that of our sidereal system1 we seem compelled to reject the hypothesis that the nebula represents an external universe4 ,the sun placed at the distance corresponding to #aej1jjj light years would1 ,i find1 shine as a star of less than the #bcrd magnitude1 a magnitude which would be invisible in the largest telescope that man could ever construct4 ,but the combined light of #d trillion of stars of even the #bcrd magnitude would be equal to one of minus #bce magnitude1 that is1 #bc-a_/b magnitude brighter than the zero magnitude1 or not very much inferior to the sun in brightness4 ,as the ,andromeda nebula shines only as a star of about the #eth magnitude the hypothesis of an external universe seems to be untenable4 ,it is evident1 however1 that the mass of the ,andromeda nebula must be enormous2 and if it belongs to our sidereal system1 and if the other great nebul have similar masses1 it seems quite possible that the mass of the visible universe may much exceed that of the visible stars1 and may be equal to #ajjj million times the sun's mass--as supposed by the late ,lord ,kelvin--or even much more4 ,with reference to the small star which suddenly blazed out near the nucleus of the ,andromeda nebula in ,august1 #ahhe1 ,prof4 ,seeliger has investigated the decrease in the light of the star on the hypothesis that it was a cooling body which had suddenly been raised to an intense heat by the shock of a collision1 and finds a fair agreement between theory and observation4 ,prof4 ,auwers points out the similarity between this outburst and that of the temporary star of #ahfj1 which appeared in the cluster #hj ,messier1 and he thinks it very probable that both phenomena were due to physical changes in the nebul in which they appeared4 ,the appearance of this temporary star in the ,andromeda nebula seems to afford further evidence against the hypothesis of the nebula being an external universe4 ,for1 as ,i have shown above1 our sun1 if placed at a distance of #aej1jjj light years1 would shine only as a star of the #bcrd magnitude1 or over #ae magnitudes fainter than the temporary star4 ,this would imply that the star shone with a brightness of over a million times that of the sun1 and would therefore indicate a body of enormous size4 ,but the rapid fading of its light would1 on the contrary1 imply a body of comparatively small dimensions4 ,we must1 therefore1 conclude that the nebula1 whatever it may be1 is not an external universe1 but forms a member of our own sidereal system4 ,in ,sir ,john ,herschel's catalogue of ,nebul and ,clusters of ,stars1 published in #ahcc1 in the ,philosophical ,transactions of the ,royal ,society1 there are many curious objects mentioned4 ,of these ,i have selected the following3-- ,no4 #dif is described as a superb cluster which fills the whole field2 stars #i1 #aj 444 #ac magnitude and none below1 but the whole ground of the sky on which it stands is singularly dotted over with infinitely minute points4 ,this is ,no4 #bb of ,sir ,william ,herschel's #fth class1 and will be found about #c degrees south and a little east of the triple star #bi ,monocerotis4 ,no4 #fej4 ,this object lies about #c degrees north of the star ,greek3 m ,leonis1 the most northern of the bright stars in the well-known ,sickle1 and is thus described by ,sir ,john ,herschel3 ,a star #abth magnitude with an extremely faint nebulous atmosphere about #aj to #ab4 ,it is between a star #h-i magnitude north preceding1 and one #ajth magnitude south following1 neither of which are so affected4 ,a curious object4 ,no4 #aeeh4 ,messier #ec4 ,a little north-east of the star ,greek3 a ,com ,berenices4 ,described as a most beautiful highly compressed cluster4 ,stars very small1 #abth 444 #bjth magnitude1 with scattered stars to a considerable distance2 irregularly round1 but not globular4 ,comes up to a blaze in the centre2 indicating a round mass of pretty equable density4 ,extremely compressed4 ,a most beautiful object4 ,a mass of close-wedged stars #e' in diameter2 a few #abth magnitude1 the rest of the smallest size and innumerable4 ,webb says1 ,not very bright with #c-g_/aj inches2 beautiful with #i inches4 ,this should be a magnificent object with a very large telescope1 like the ,lick or ,yerkes4 ,no4 #bjah4 ,a more than usually condensed portion of the enormous cluster of the ,milky ,way4 ,the field has #bjj or #cjj stars in it at once4 ,this lies about #b south-west of the star #f ,aquil1 which is near the northern edge of the bright spot of ,milky ,way light in ,sobieski's ,shield--one of the brightest spots in the sky4 ,no4 #bjic4 ,a most wonderful phenomenon4 ,a very large space #bj' or #cj' broad in ,polar ,distance1 and #am or #bm in ,right ,ascension1 full of nebula and stars mixed4 ,the nebula is decidedly attached to the stars1 and is as decidedly not stellar4 ,it forms irregular lace-work marked out by stars1 but some parts are decidedly nebulous1 wherein no star can be seen4 ,sir ,john ,herschel gives a figure of this curious spot1 which he says represents its general character1 but not the minute details of this object1 which would be extremely difficult to give with any degree of fidelity4 ,it lies about #c degrees west of the bright star ,greek3 z ,cygni4 ,among the numerous curious objects observed by ,sir ,john ,herschel during his visit to the ,cape of ,good ,hope1 the following may be mentioned3-- h #becd 7,h iv4 #gg74 ,near ,greek3 t#d ,eridani4 ,sir ,john ,herschel says1 ,attached cometically to a #ith magnitude star which forms its head4 ,it is an exact resemblance to ,halley's comet as seen in a night glass4444 ,a complete telescopic comet2 a perfect miniature of ,halley's comet1 only the tail is rather broader in proportion4#cfg h #cjge4 ,between ,greek3 g ,monocerotis and ,greek3 g ,canis ,majoris4 ,a very singular nebula1 and much like the profile of a bust 7head1 neck1 and shoulders7 or a silhouette portrait1 very large1 pretty well defined1 light nearly uniform1 about #ab' diameter4 ,in a crowded field of ,milky ,way stars1 many of which are projected on it4#cfh h #ccae 7,dunlop #cbc74 ,in the ,milky ,way2 about #c east of the ,eta ,args nebula4 ,sir ,john ,herschel says1 ,a glorious cluster of immense magnitude1 being at least #b fields in extent every way4 ,the stars are #h1 #i1 #aj1 and #aath magnitudes1 but chiefly #ajth magnitude1 of which there must be at least #bjj4 ,it is the most brilliant object of the kind ,i have ever seen 444 has several elegant double stars1 and many orange-coloured stars4#cfi ,this should form a fine object in even a comparatively small telescope1 and may be recommended to observers in the southern hemisphere4 ,a telescope of #c-;inches aperture should show it well4 ,among astronomical curiosities may be counted clusters within clusters4 ,a cluster in ,gemini 7,n4,g4,c4 #bcca7 has a small group of six or seven stars close together and well isolated from the rest4 ,lord ,rosse describes ,no4 #deaa of ,sir ,john ,herschel's ,general ,catalogue of ,nebul and ,clusters 7,phil4 ,trans41 #ahfd7 as a most gorgeous cluster1 stars #ab-ae magnitude1 full of holes4#cgj ,his sketch of this cluster shows #c rings of stars in a line1 each ring touching the next on the outside4 ,sir ,john ,herschel described it as ,cluster2 very large2 very rich2 stars #aa-ae magnitude 7,harding1 #ahbg71 but says nothing about the rings4 ,this cluster lies about #e degrees south of ,greek3 d ,cygni4 ,dr4 ,see1 observing with the large telescope of the ,lowell ,observatory1 found that when the sky is clear1 the moon absent1 and the seeing perfect1 the sky appeared in patches to be of a brownish colour1 and suggests that this colour owes its existence to immense cosmical clouds1 which are shining by excessively feeble light6 ,dr4 ,see found that these brown patches seem to cluster in certain regions of the ,milky ,way4#cga ,from a comparison of ,trouvelot's drawing of the small elongated nebula near the great nebula in ,andromeda with recent photographs1 ,mr4 ,easton infers that this small nebula has probably rotated through an angle of about #ae in #be years4 ,an examination ,i have made of photographs taken in different years seems to me to confirm this suspicion1 which1 if true1 is evidently a most interesting phenomenon4 ,dr4 ,max ,wolf of ,heidelberg finds1 by spectrum photography1 that the well-known ring nebula in ,lyra consists of four rings composed of four different gases4 ,calling the inner ring ,a1 the next ,b1 the next ,c1 and the outer ,d1 he finds that ,a is the smallest ring1 and is composed of an unknown gas2 the next largest1 ,b1 is composed of hydrogen gas2 the next1 ,c1 consists of helium gas2 and the outer and largest ring1 ,d1 is composed--like ,a--of an unknown gas4 ,as the molecular weight of hydrogen is #bjaf1 and that of helium is #cif1 ,prof4 ,bohuslav ,brauner suggests that the molecular weight of the gas composing the inner ring ,a is smaller than that of hydrogen1 and the molecular weight of the gas forming the outer ring ,d is greater than that of helium4 ,he also suggests that the gas of ring ,a may possibly be identical with the coronium of the solar corona1 for which ,mendelief found a hypothetical atomic and molecular weight of #jd4cgb ,with reference to the nebular hypothesis of ,laplace1 ,dr4 ,a4 ,r4 ,wallace argues that if there exists a sun in a state of expansion in which our sun was when it extended to the orbit of ,neptune1 it would1 even with a parallax of #a_/fjth of a second1 show a disc of half a second1 which could be seen with the ,lick telescope4 ,my reply to this objection is1 that with such an expansion there would probably be very little intrinsic brightness1 and if luminous enough to be visible the spectrum would be that of a gaseous nebula1 and no known star gives such a spectrum4 ,but some planetary nebul look like small stars1 and with high powers on large telescopes would probably show a disc4 ,on these considerations1 ,dr4 ,wallace's objection does not seem to be valid4 ,it is usually stated in popular works on astronomy that the spectra of gaseous nebul show only three or four bright lines on a faint continuous background4 ,but this is quite incorrect4 ,no less than forty bright lines have been seen and measured in the spectra of gaseous nebul4#cgc ,this includes #b lines of nebulium1 #aa of hydrogen1 #e of helium1 #a of oxygen 7871 #c of nitrogen 7871 #a of silicon 7871 and #ag of an unknown substance4 ,in the great nebul in ,orion #cj bright lines have been photographed4#cgd ,d',arrest found that gaseous nebul are rarely met with outside the ,milky ,way1 and never at a considerable distance from it4#cge ,mr4 ,a4 ,e4 ,fath thinks that no spiral nebula investigated has a truly continuous spectrum4 ,he finds that so feeble is the intensity of the light of the spiral nebul that1 while a spectrogram of ,arcturus can be secured with the ,mills spectrograph in less than two minutes1 an exposure of about #ejj hours would be required for the great nebula in ,andromeda1 which is of the same spectral type4#cgf ,mr4 ,fath thinks that in the case of the ,andromeda nebula1 the star cluster theory seems to be the only one that can at all adequately explain the spectrum obtained4#cgg ,prof4 ,barnard finds that the great cluster in ,hercules 7,messier #ac7 is composed of stars of different spectral types4 ,this result was confirmed by ,mr4 ,fath4#cgh ,from observations with the great #dj-;inch telescope of the ,yerkes ,observatory 7,u4,s4,a471 ,prof4 ,barnard finds that the nucleus of the planetary nebula ,h4 iv4 #ah in ,andromeda is variable to the extent of at least #c magnitudes4 ,at its brightest it is about the #abth magnitude2 and the period seems to be about #bh days4 ,barnard says1 ,i think this is the first case in which the nucleus of a planetary or other nebula has been shown to be certainly variable4 ,the normal condition seems to be faint--the nucleus remaining bright for a few days only4 ,in an ordinary telescope it looks like a small round disc of a bluish green colour4 ,he estimated the brightness of the nebula as that of a star of #hb magnitude4#cgi ,even in a telescope of #d inches aperture1 this would be a fairly bright object4 ,it lies about #c-a_/b degrees south-west of the star ,greek3 i ,andromed4 ,the so-called globular clusters usually include stars of different brightness2 comparatively bright telescopic stars of the #ajth to #acth magnitude with faint stars of the #aeth to #agth magnitude4 ,prof4 ,perrine of the ,lick ,observatory finds that 7a7 the division of the stars in globular clusters into groups1 differing widely in brightness1 is characteristic of these objects2 7b7 the globular clusters are devoid of true nebulosity2 and 7c7 stars fainter than #aeth magnitude predominate in the ,milky ,way and globular clusters1 but elsewhere are relatively scarce4 ,he found that exposures of one hour or thereabouts showed as many stars as exposures four to six times as long2 the only effect of the longer exposures being in the matter of density4 ,this last result confirms the late ,dr4 ,roberts' conclusions4 ,perrine finds that for clusters in the ,milky ,way1 the faint stars 7#aeth to #agth magnitude7 are about as numerous in proportion to the bright stars 7#ajth to #acth magnitude7 as in the globular clusters themselves4 ,this is1 however1 not the case with globular clusters at a distance from the ,milky ,way4 ,in these latter clusters he found that in the regions outside the limits of the cluster there are usually very few faint stars1 hardly more than one-fourth or one-tenth as many as there are bright stars2 and he thinks that this paucity of faint stars in the vicinity of these clusters gives rise to the suspicion that all regions at a distance from the ,galaxy may be almost devoid of these very faint stars4 ,the late ,prof4 ,keeler's series of nebular photographs in or near the ,milky ,way tend to confirm the above conclusions4 ,perrine finds the northernmost region of the ,milky ,way to be almost1 if not entirely1 devoid of globular clusters4#chj ,according to ,sir ,john ,herschel1 the sublimity of the spectacle afforded by ,lord ,rosse's great telescope of #f feet in diameter of some of the larger globular and other clusters is declared by all who have witnessed it1 to be such that no words can express4#cha ,in his address to the ,british ,association at ,leicester in #aijg1 ,sir ,david ,gill said-- ,evidence upon evidence has accumulated to show that nebul consist of the matter out of which stars have been and are being evolved4444 ,the fact of such an evolution with the evidence before us1 can hardly be doubted4 ,i most fully believe that1 when the modifications of terrestrial spectra under sufficiently varied conditions of temperature1 pressure1 and environment1 have been further studied1 this connection will be greatly strengthened4 ,,chapter ,,xviii ,historical ,the grouping of the stars into constellations is of great antiquity4 ,the exact date of their formation is not exactly known1 but an approximate result may be arrived at from the following considerations4 ,on the celestial spheres1 or globes1 used by the ancient astronomers1 a portion of the southern heavens of a roughly circular form surrounding the ,south ,pole was left blank4 ,this space presumably contained the stars in the southern hemisphere which they could not see from their northern stations4 ,now1 the centre of this circular blank space most probably coincided with the ,south ,pole of the heavens at the time when the constellations were first formed4 ,owing to the ,precession of the ,equinoxes this centre has now moved away from the ,south ,pole to a considerable distance4 ,it can be easily computed at what period this centre coincided with the ,south ,pole1 and calculations show that this was the case about #bgjj ,b4,c4 ,the position of this circle also indicates that the constellations were formed at a place between #cf and #dj north latitude1 and therefore probably somewhere in ,asia ,minor north of ,mesopotamia4 ,again1 the most ancient observations refer to ,taurus as the equinoxial constellation4 ,virgil says-- ,candidus auratis aperit cum cornibus annum ,taurus4#chb ,this would indicate a date about #cjjj ,b4,c4 ,there is no tradition1 however1 that the constellation ,gemini was ever seen to occupy this position1 so that #cjjj ,b4,c4 seems to be the earliest date admissible4#chc ,prof4 ,sayce thinks that the signs of the ,zodiac had their origin in the plains of ,mesopotamia in the twentieth or twenty-third century ,b4,c41 and ,brown gives the probable date as #bjhd ,b4,c4#chd ,according to ,seneca1 the study of astronomy among the ,greeks dates back to about #adjj ,b4,c42 and the ancient constellations were already classical in the time of ,eudoxus in the fourth century ,b4,c4 ,eudoxus 7#djh-cee ,b4,c47 observed the positions of forty-seven stars visible in ,greece1 thus forming the most ancient star catalogue which has been preserved4 ,he was a son of ,eschinus1 and a pupil of ,archytas and probably ,plato4 ,the work of ,eudoxus was put into verse by the poet ,aratus 7third century ,b4,c474 ,this poem describes all the old constellations now known1 except ,libra1 the ,balance1 which was at that time included in the ,claws of the ,scorpion4 ,about ,b4,c4 #ej1 the ,romans changed the ,claws1 or ,chel1 into ,libra4 ,curious to say1 ,aratus states that the constellation ,lyra contained no bright star6#che ,whereas its principal star1 ,vega1 is now one of the brightest stars in the heavens6 ,with reference to the origin of the constellations1 ,aratus says-- ,some men of yore ,a nomenclature thought of and devised ,and forms sufficient found4 ,this shows that even in the time of ,aratus the constellations were of great antiquity4 ,brown says-- ,writers have often told us1 speaking only from the depths of their ignorance1 how ',chaldean' shepherds were wont to gaze at the brilliant nocturnal sky1 and to imagine that such and such stars resemble this or that figure4 ,but all this is merely the old effort to make capital out of nescience1 and the stars are before our eyes to prove the contrary4 ,having already certain fixed ideas and figures in his mind1 the constellation-former1 when he came to his task1 applied his figures to the stars and the stars to his figures as harmoniously as possible4#chf ,thus e4g4 he arranged the stars of ,andromeda into the representation of a chained lady1 not because they naturally reminded him 7or anybody else7 of such a figure1 but because he desired to express that idea4 ,a coin of ,manius ,aquillus1 ,b4,c4 #id1 shows four stars in ,aquila1 and seems to be the oldest representation extant of a star group4 ,on a coin of ,b4,c4 #dc1 ,dr4 ,vencontre found five stars1 one of which was much larger than the others1 and concludes that it represents the ,hyades 7in ,taurus74 ,he attributes the coin to ,p4 ,clodius ,turrinus1 who probably used the constellation ,taurus or ,taurinus as a phonetic reference to his surname4 ,a coin struck by ,l4 ,lucretius ,trio in #gd ,b4,c41 shows the seven stars of the ,plough1 or as the ancients called them ,septem ,triones4 ,here we have an allusion to the name of the magistrate ,trio4#chg ,in a work published in ,berne in #agfj1 ,schmidt contends that the ancient ,egyptians gave to the constellations of the ,zodiac the names of their divinities1 and expressed them by the signs which were used in their hieroglyphics4#chh ,hesiod mentions ,orion1 the ,pleiades1 ,sirius1 ,aldebaran1 and ,arcturus2 and ,homer refers to ,orion1 ,arcturus1 the ,pleiades1 the ,hyades1 the ,great ,bear 7under the name of ,amaxa1 the ,chariot71 and the tail of the ,little ,bear1 or ,cynosura4 ,hipparchus called the constellations ,asterisms 7,greek3 asterismos71 ,aristotle and ,hyginus ,greek3 ,somata 7bodies71 and ,ptolemy ,greek3 ,schmata 7figures74 ,by some they were called ,greek3 ,morphseis 7configurations71 and by others ,greek3 ,metere4 ,proclus called those near the ecliptic ,greek3 ,zdia 7animals74 ,hence our modern name ,zodiac4 ,hipparchus1 ,ptolemy1 and ,al-,sufi referred the positions of the stars to the ecliptic4 ,they are now referred to the equator4 ,aboul ,hassan in the thirteenth century 7#abhb7 was the first to use ,right ,ascensions and ,declinations instead of ,longitudes and ,latitudes4 ,the ancient writers described the stars by their positions in the ancient figures4 ,thus they spoke of the star in the head of ,hercules1 the bright star in the left foot of ,orion 7,rigel72 but ,bayer in #afjc introduced the ,greek letters to designate the brighter stars1 and these are now universally used by astronomers4 ,these letters being sometimes insufficient1 ,hevelius added numbers1 but the numbers in ,flamsteed's ,catalogue are now generally used4 ,ptolemy and all the ancient writers described the constellation figures as they are seen on globes1 that is from the outside4 ,bayer in his ,atlas1 published in #afjc1 reversed the figures to show them as they would be seen from the interior of a hollow globe and as1 of course1 they are seen in the sky4 ,hevelius again reversed ,bayer's figures to make them correspond with those of ,ptolemy4 ,according to ,bayer's arrangement1 ,betelgeuse 7,greek3 a ,orionis7 would be on the left shoulder of ,orion1 instead of the right shoulder according to ,ptolemy and ,al-,sufi1 and ,rigel 7,greek3 b ,orionis7 on the right foot 7,bayer7 instead of the left foot 7,ptolemy74 ,this change of position has led to some confusion2 but at present the positions of the stars are indicated by their ,right ,ascensions and ,declinations1 without any reference to their positions in the ancient figures4 ,the classical constellations of ,hipparchus and ,ptolemy number forty-eight1 and this is the number described by ,al-,sufi in his ,description of the ,fixed ,stars written in the tenth century ,a4,d4 ,firminicus gives the names of several constellations not mentioned by ,ptolemy4 ,m4 ,frret thought that these were derived from the ,egyptian sphere of ,petosiris4 ,of these a ,fox was placed north of the ,scorpion2 a constellation called ,cynocephalus near the southern constellation of the ,altar 7,ara72 and to the north of ,pisces was placed a ,stag4 ,but all these have long since been discarded4 ,curious to say neither the ,dragon nor ,cepheus appears on the old ,egyptian sphere4#chi ,other small constellations have also been formed by various astronomers from time to time1 but these have disappeared from our modern star maps4 ,the total number of constellations now recognized in both hemispheres amounts to eighty-four4 ,the first catalogue formed was nominally that of ,eudoxus in the fourth century ,b4,c4 7about #cgj ,b4,c474 ,but this can hardly be dignified by the name of catalogue1 as it contained only forty-seven stars1 and it omits several of the brighter stars1 notably ,sirius6 ,the first complete 7or nearly complete7 catalogue of stars visible to the naked eye was that of ,hipparchus about #abi ,b4,c4 ,ptolemy informs us that it was the sudden appearance of a bright new or temporary star in the year #acd ,b4,c4 in the constellation ,scorpio which led ,hipparchus to form his catalogue1 and there seems to be no reason to doubt the accuracy of this statement1 as the appearance of this star is recorded in the ,chinese ,annals4 ,the ,catalogue of ,hipparchus contains only #ajhj stars2 but as many more are visible to the naked eye1 ,hipparchus must have omitted those which are not immediately connected with the old constellation figures of men and animals4 ,hipparchus' ,catalogue was revised by ,ptolemy in his famous work the ,almagest4 ,ptolemy reduced the positions of the stars given by ,hipparchus to the year #acg ,a4,d42 but used a wrong value of the precession which only corresponded to about #ej ,a4,d42 and he probably adopted the star magnitudes of ,hipparchus without any revision4 ,indeed1 it seems somewhat doubtful whether ,ptolemy made any observations of the brightness of the stars himself4 ,ptolemy's catalogue contains #ajbb stars4 ,prof4 ,de ,morgan speaks of ,ptolemy as a splendid mathematician and an indifferent observer2 and from my own examination of ,al-,sufi's work on the ,fixed ,stars1 which was based on ,ptolemy's work1 ,i think that ,de ,morgan's criticism is quite justified4 ,al-,sufi's ,description of the ,fixed ,stars was written in the tenth century and contains #ajah stars4 ,he seems to have adopted the positions of the stars given by ,ptolemy1 merely correcting them for the effects of precession2 but he made a very careful revision of the star magnitudes of ,ptolemy 7or ,hipparchus7 from his own observations1 and this renders his work the most valuable1 from this point of view1 of all the ancient catalogues4 ,very little is known about ,al-,sufi's life1 and the few details we have are chiefly derived from the works of the historians ,abu'-l-faradji and ,casiri1 and the ,oriental writers ,hyde1 ,caussin1 ,sedillot1 etc4 ,al-,sufi's complete name was ,abd-al-,rahmn ,bin ,umar ,bin ,muhammad ,bin ,sahl ,abu'l-husan al-,sufi al-,razi4 ,the name ,sufi indicates that he belonged to the sect of ,sufis 7,dervishes71 and the name ,razi that he lived in the town of ,ra in ,persia1 to the east of ,teheran4 ,he was born on ,december #g1 #ijc ,a4,d41 and died on ,may #be1 #ihf1 so that1 like many other astronomers1 he lived to a good old age4 ,according to ancient authorities1 ,al-,sufi--as he is usually called--was a very learned man1 who lived at the courts of ,schiraz and ,baghdad under ,adhad-al-,davlat--of the dynasty of the ,budes--who was then the ruler of ,persia4 ,al-,sufi was held in high esteem and great favour by this prince1 who said of him1 ,abd-al-,rahmn al-,sufi taught me to know the names and positions of the fixed stars1 ,scharif ,ibn al-,aalam the use of astronomical tables1 and ,abu ,ali al-,farisi instructed me in the principles of grammar4 ,prince ,adhad-al-,davlat died on ,march #bf1 #ihc4 ,according to ,caussin1 ,al-,sufi also wrote a book on astrology1 and a work entitled ,al-,ardjouze1 which seems to have been written in verse1 but its subject is unknown4 ,he also seems to have determined the exact length of the year1 and to have undertaken geodetic measurements4 ,the al-,aalam mentioned above was also an able astronomer1 and in addition to numerous observations made at ,baghdad1 he determined with great care the precession of the equinoxes4 ,he found the annual constant of precession to be #ead1 a value which differs but little from modern results4 ,in the year #ahgd1 the late ,m4 ,schjellerup1 the eminent ,danish astronomer1 published a ,french translation of two ,arabic manuscripts written by ,al-,sufi and entitled ,a ,description of the ,fixed ,stars4 ,one of these manuscripts is preserved in the ,royal ,library at ,copenhagen1 and the other in the ,imperial ,library at ,st4 ,petersburgh4#cij ,al-,sufi seems to have been a most careful and accurate observer1 and although1 as a rule1 his estimates of the relative brightness of stars are in fairly good agreement with modern estimates and photometric measures1 there are many remarkable and interesting differences4 ,al-,sufi's observations have an important bearing on the supposed secular variation of the stars2 that is1 the slow variation in light which may have occurred in the course of ages in certain stars1 apart from the periodical variation which is known to occur in the so-called variable stars4 ,more than #ijj years have now elapsed since the date of ,al-,sufi's observations 7about ,a4,d4 #ifd7 and over #bjjj years in the case of ,hipparchus1 and although these periods are of course very short in the life-history of any star1 still some changes may possibly have taken place in the brightness of some of them4 ,there are several cases in which a star seems to have diminished in light since ,al-,sufi's time4 ,this change seems to have certainly occurred in the case of ,greek3 th ,eridani1 ,greek3 b ,leonis1 ,greek3 z ,piscis ,australis1 and some others4 ,on the other hand1 some stars seem to have certainly increased in brightness1 and the bearing of these changes on the question of stellar evolution will be obvious4 ,in most cases ,al-,sufi merely mentions the magnitude which he estimated a star to be2 such as third magnitude1 fourth1 small third magnitude1 large fourth1 etc4 ,in some cases1 however1 he directly states that a certain star is a little brighter than another star near it4 ,such cases--unfortunately not numerous--are very valuable for comparison with modern estimates and measures1 when variation is suspected in the light of a star4 ,the estimates of ,argelander1 ,heis1 and ,houzeau are based on the same scale as that used by ,ptolemy and ,al-,sufi4 ,al-,sufi's estimates are given in thirds of a magnitude4 ,thus1 small third magnitude means #c-a_/c1 or #ccc magnitude in modern measures2 large fourth1 #c-b_/c or #cff magnitude4 ,these correspond with the estimates of magnitude given by ,argelander1 ,heis1 and ,houzeau in their catalogues of stars visible to the naked eye1 and so the estimates can be directly compared4 ,i have made an independent identification of all the stars mentioned by ,al-,sufi4 ,in the majority of cases my identifications concur with those of ,schjellerup2 but in some cases ,i cannot agree with him4 ,in a few cases ,i have found that ,al-,sufi himself1 although accurately describing the position of the stars observed by him1 has apparently misidentified the star observed by ,hipparchus and ,ptolemy4 ,this becomes evident when we plot ,ptolemy's positions 7as given by ,al-,sufi7 and compare them with ,al-,sufi's descriptions of the stars observed by him4 ,this ,i have done in all cases where there seemed to be any doubt2 and in this way ,i have arrived at some interesting results which have escaped the notice of ,schjellerup4 ,this examination shows clearly1 ,i think1 that ,al-,sufi did not himself measure the positions of the stars he observed1 but merely adopted those of ,ptolemy1 corrected for the effect of precession4 ,the great value of his work1 however1 consists in his estimates of star magnitudes1 which seem to have been most carefully made1 and from this point of view1 his work is invaluable4 ,prof4 ,pierce says1 ,the work which the learning of ,m4 ,schjellerup has brought to light is so important that the smallest errors of detail become interesting4#cia ,although ,al-,sufi's work is mentioned by the writers referred to above1 no complete translation of his manuscript was made until the task was undertaken by ,schjellerup1 and even now ,al-,sufi's name is not mentioned in some popular works on astronomy6 ,but he was certainly the best of all the old observers1 and his work is deserving of the most careful consideration4 ,al-,sufi's descriptions of the stars were1 it is true1 based on ,ptolemy's catalogue1 but his work is not a mere translation of that of his predecessor4 ,it is1 on the contrary1 a careful and independent survey of the heavens1 made from his own personal observations1 each of ,ptolemy's stars having been carefully examined as to its position and magnitude1 and ,ptolemy's mistakes corrected4 ,in examining his descriptions1 ,schjellerup says1 ,we soon see the vast extent of his labours1 his perseverance1 and the minute accuracy and almost modern criticism with which he executed his work4 ,in fact1 ,al-,sufi has given us a careful description of the starry sky as it appeared in his time1 and one which deserves the greatest confidence4 ,it far surpasses the work of ,ptolemy1 which had been without a rival for eight centuries previously1 and it has only been equalled in modern times by the surveys of ,argelander1 ,gould1 ,heis1 and ,houzeau4 ,plato remarked with reference to the catalogue of ,hipparchus1 ,coelam posteris in hereditatem relictum1 and the same may be said of ,al-,sufi's work4 ,in addition to his own estimates of star magnitudes1 ,al-,sufi adds the magnitudes given by ,ptolemy whenever ,ptolemy's estimate differs from his own2 and this makes his work still more valuable1 as ,ptolemy's magnitudes given in all the editions of the ,almagest now extant are quite untrustworthy4 ,in the preface to his translation of ,al-,sufi's work1 ,schjellerup mentions some remarkable discrepancies between the magnitudes assigned to certain stars by ,ptolemy and ,argelander4 ,this comparison is worthy of confidence as it is known that both ,al-,sufi and ,argelander adopted ,ptolemy's 7or ,hipparchus'7 scale of magnitudes4 ,for example1 all these observers agree that ,greek3 b ,urs ,minoris 7,ptolemy's ,no4 #f of that constellation7 is of the #bnd magnitude1 while in the case of ,greek3 g ,urs ,minoris 7,ptolemy's ,no4 #g71 ,ptolemy called it #bnd1 and ,argelander rated it #crd2 ,argelander thus making ,greek3 g one magnitude fainter than ,ptolemy's estimate4 ,now1 ,al-,sufi1 observing over #ijj years ago1 rated ,greek3 g of the #crd magnitude1 thus correcting ,ptolemy and agreeing with ,argelander4 ,modern photometric measures confirm the estimates of ,al-,sufi and ,argelander4 ,but it is1 of course1 possible that one or both stars may be variable in light1 and ,greek3 b has actually been suspected of variation4 ,almost all the constellations afford examples of this sort4 ,in the majority of cases1 however1 ,al-,sufi agrees well with ,argelander and ,heis1 but there are in some cases differences which suggest a change in relative brightness4 ,among other remarkable things contained in ,al-,sufi's most interesting work may be mentioned the great nebula in ,andromeda1 which was first noticed in ,europe as visible to the naked eye by ,simon ,marius in #afab4 ,al-,sufi1 however1 speaks of it as a familiar object in his time4 ,schjellerup says-- ,for a long time many of the stars in ,ptolemy's catalogue could not be identified in the sky4 ,most of these discordances were certainly due to mistakes in copying1 either in longitude or latitude4 ,many of these differences were1 however1 corrected by the help of new manuscripts4 ,for this purpose ,al-,sufi's work is of great importance4 ,by a direct examination of the sky he succeeded in finding nearly all the stars reported by ,ptolemy 7or ,hipparchus74 ,and even if his criticism may sometimes seem inconclusive1 his descriptions are not subject to similar defects1 his positions not depending solely on the places given in ,ptolemy's catalogue4 ,for1 in addition to the longitudes and latitudes quoted from ,ptolemy1 he has described by alignment the positions of the stars referred to4 ,in going from the brightest and best known stars of each constellation he indicates the others either by describing some peculiarity in their position1 or by giving their mutual distance as so many cubits 7dzir71 or a span 7schibr71 units of length which were used at that time to measure apparent celestial distances4 ,the term dzir means literally the fore-arm from the bone of the elbow to the tip of the middle finger1 or an ell4 ,we should not1 however1 conclude from this that the ,arabians were so unscientific as to measure celestial distances by an ell1 as this would be quite in contradiction to their well-known knowledge of ,geometry and ,trigonometry4 ,with reference to the arc or angular distance indicated by the cubit1 ,al-,sufi states in his description of the constellation ,auriga that the dzir 7or cubit7 is equal to #b #bj'4 ,three cubits1 therefore1 represent #g1 and #d cubits #i #bj'4 ,in ,al-,sufi's own preface to his work1 after first giving glory to ,god and blessings on his elected messenger ,muhammed and his family1 he proceeds to state that he had often met with many persons who wished to know the fixed stars1 their positions on the celestial vault1 and the constellations1 and had found that these persons may be divided into two classes4 ,one followed the method of astronomers and trust to spheres designed by artists1 who not knowing1 the stars themselves1 take only the longitudes and latitudes which they find in the books1 and thus place the stars on the sphere1 without being able to distinguish truth from error4 ,it then follows that those who really know the stars in the sky find on examining these spheres that many stars are otherwise than they are in the sky4 ,among these are ,al-,battani1 ,atrid and others4 ,al-,sufi seems rather hard on ,al-,battani 7or ,albategnius as he is usually called7 for he is generally considered to have been the most distinguished of the ,arabian astronomers4 ,his real name was ,mohammed ,ibn ,jaber ,ibn ,senan ,abu ,abdallah ,al-,harrani4 ,he was born about ,a4,d4 #hej at ,battan1 near ,harran in ,mesopotamia1 and died about ,a4,d4 #ibi4 ,he was the first to make use of sines instead of chords1 and versed sines4 ,the ,alphonsine ,tables of the moon's motions were based on his observations4 ,after some severe criticisms on the work of ,al-,battani and ,atrid1 ,al-,sufi goes on to say that the other class of amateurs who desire to know the fixed stars follow the method of the ,arabians in the science of ,anva#cib and the mansions of the moon and the books written on this subject4 ,al-,sufi found many books on the anva1 the best being those of ,abu ,hanifa al-,dnavari4 ,this work shows that the author knew the ,arabic tradition better than any of the other writers on the subject4 ,al-,sufi1 however1 doubts that he had a good knowledge of the stars themselves1 for if he had he would not have followed the errors of his predecessors4 ,according to ,al-,sufi1 those who know one of these methods do not know the other4 ,among these is ,abu-,hanifa1 who states in his book that the names of the twelve signs 7of the ,zodiac7 did not originate from the arrangement or configuration of the stars resembling the figure from which the name is derived4 ,the stars1 ,abu-,hanifa said1 change their places1 and although the names of the signs do not change1 yet the arrangement of the stars ceases to be the same4 ,this shows that he was not aware of the fact that the arrangement of the stars does not change1 and their mutual distances and their latitudes1 north and south of the ecliptic1 are neither increased nor diminished4 ,the stars1 ,al-,sufi says1 do not change with regard to their configurations1 because they are carried along together by a physical motion and by a motion round the poles of the ecliptic4 ,this is why they are called fixed4 ,abu-,hanifa supposed that they are termed fixed because their motion is very slow in comparison with that of the planets4 ,these facts1 he says1 can only be known to those who follow the method of the astronomers and are skilled in mathematics4 ,al-,sufi says that the stars of the ,zodiac have a certain movement following the order of the signs1 which according to ,ptolemy and his predecessors is a degree in #ajj years4 ,but according to the authors of al-mumtahan and those who have observed subsequently to ,ptolemy1 it is a degree in #ff years4 ,according to modern measures1 the precession is about #ejce per annum1 or one degree in #ga-a_/b years4 ,al-,sufi says that the ,arabians did not make use of the figures of the ,zodiac in their proper signification1 because they divided the circumference of the sky by the number of days which the moon took to describe it--about #bh days--and they looked for conspicuous stars at intervals which1 to the eye1 the moon appeared to describe in a day and a night4 ,they began with al-scharatan1 the two marks 7,greek3 a and ,greek3 b ,arietis7 which were the first striking points following the point of the spring equinox4 ,they then sought behind these two marks another point at a distance from them1 equal to the space described by the moon in a day and a night4 ,in this way they found al-butan 7,greek3 e1 ,greek3 d1 and ,greek3 r ,arietis72 after that al-tsuraija1 the ,pleiades2 then al-dabaran1 the ,hyades1 and thus all the mansions of the moon4 ,they paid no attention to the signs of the ,zodiac1 nor to the extent of the figures which composed them4 ,this is why they reckoned among the mansions al-haka 7,greek3 l ,orionis7 which forms no part of the signs of the ,zodiac1 since it belongs to the southern constellation of the ,giant 7,orion74 ,and similarly for other stars near the ,zodiac1 of which ,al-,sufi gives some details4 ,he says that ,regulus 7,greek3 a ,leonis7 was called by the ,arabians al-maliki1 the ,royal ,star1 and that al-anva consists of five stars situated in the two wings of the ,virgin4 ,these stars seem to be ,greek3 b1 ,greek3 1 ,greek3 g1 ,greek3 d1 and ,greek3 e ,virginis1 which form with ,spica 7,greek3 a ,virginis7 a ,y-shaped figure4 ,spica was called simak al-azal1 the unarmed simak2 the armed simak being ,arcturus1 simak al-ramih4 ,these old ,arabic names seem very fanciful4 ,al-,sufi relates that in the year #ccg of the ,hegira 7about ,a4,d4 #idh7 he went to ,ispahan with ,prince ,abul-fadhl1 who introduced him to an inhabitant of that city1 named ,varvadjah1 well known in that country1 and famous for his astronomical acquirements4 ,al-,sufi asked him the names of the stars on an astrolabe which he had1 and he named ,aldebaran1 the two bright stars in the ,twins 7,castor and ,pollux71 ,regulus1 ,sirius1 and ,procyon1 the two ,simaks1 etc4 ,al-,sufi also asked him in what part of the sky ,al-fard 7,greek3 a ,hydr7 was1 but he did not know6 ,afterwards1 in the year #cdi1 this same man was at the court of ,prince ,adhad-al-,davlat1 and in the presence of the ,prince1 ,al-,sufi asked him the name of a bright star--it was al-nasr al-vaki1 the falling ,vulture 7,vega71 and he replied1 ,that is al-aijuk 7,capella76 thus showing that he only knew the names of the stars1 but did not know them when he saw them in the sky4 ,al-,sufi adds that all the women who spin in their houses knew this star 7,vega7 by the name of al-atsafi1 the ,tripod4 ,but this could not be said even of educated women at the present day4 ,with reference to the number of stars which can be seen with the naked eye1 ,al-,sufi says1 ,many people believe that the total number of fixed stars is #ajbe1 but this is an evident error4 ,the ancients only observed this number of stars1 which they divided into six classes according to magnitude4 ,they placed the brightest in the #ast magnitude2 those which are a little smaller in the #bnd2 those which are a little smaller again in the #crd2 and so on to the #fth4 ,as to those which are below the #fth magnitude1 they found that their number was too great to count2 and this is why they have omitted them4 ,it is easy to convince one's self of this4 ,if we attentively fix our gaze on a constellation of which the stars are well known and registered1 we find in the spaces between them many other stars which have not been counted4 ,take1 for example1 the ,hen ,cygnus2 it is composed of seventeen internal stars1 the first on the beak1 the brightest on the tail1 the others on the wings1 the neck and the breast2 and below the left wing are two stars which do not come into the figure4 ,between these different stars1 if you examine with attention1 you will perceive a multitude of stars1 so small and so crowded that we cannot determine their number4 ,it is the same with all the other constellations4 ,these remarks are so correct that they might have been written by a modern astronomer4 ,it should be added1 however1 that all the faint stars referred to by ,al-,sufi--and thousands of others still fainter--have now been mapped down and their positions accurately determined4 ,about the year #adcg1 ,ulugh ,beigh1 son of ,shah ,rokh1 and grandson of the ,mogul ,emperor ,tamerlane1 published a catalogue of stars in which he corrected ,ptolemy's positions4 ,but he seems to have accepted ,al-,sufi's star magnitudes without any attempt at revision4 ,this is unfortunate1 for an independent estimate of star magnitudes made in the fifteenth century would now be very valuable for comparison with ,al-,sufi's work and with modern measures4 ,ulugh ,beigh's catalogue contains #ajah stars1 nearly the same number as given by ,ali-,sufi4#cic ,,chapter ,,xix ,the ,constellations#cid ,curious to say1 ,al-,sufi rated the ,pole ,star as #crd magnitude2 for it is now only slightly less than the #bnd4 ,at present it is about the same brightness as ,greek3 b of the same constellation 7,ursa ,minor7 which ,al-,sufi rated #bnd magnitude4 ,it was1 however1 also rated #crd magnitude by ,ptolemy 7or ,hipparchus71 and it may possibly have varied in brightness since ancient times4 ,admiral ,smyth says that in his time 7#ahcj7 it was not even a very bright third size 767#cie ,spectroscopic measures show that it is approaching the earth at the rate of #af miles a second2 but this would have no perceptible effect on its brightness in historical times4 ,this may seem difficult to understand1 and to some perhaps incredible2 but the simple explanation is that its distance from the earth is so great that a journey of even #bjjj years with the above velocity would make no appreciable difference in its distance6 ,this is undoubtedly true1 as a simple calculation will show1 and the fact will give some idea of the vast distance of the stars4 ,the well-known #ith magnitude companion to the ,pole ,star was seen by day in the ,dorpat telescope by ,struve and ,wrangel2 and on one occasion by ,encke and ,argelander4#cif ,the star ,greek3 b ,urs ,minoris was called by the ,arabians ,kaukab al-shamli1 the ,north ,star1 as it was--owing to the precession of the ,equinoxes--nearer to the ,pole in ancient times than our present ,pole ,star was then4 ,the ,plough 7or ,great ,bear7 is supposed to represent a waggon and horses4 ,charles' ,wain is a corruption of churl's wain1 or peasant's cart4 ,the ,arabians thought that the four stars in the quadrilateral represented a bier1 and the three in the tail the children of the deceased following as mourners6 ,in the ,greek mythology1 ,ursa ,major represented the nymph ,callisto1 a daughter of ,lycaon1 who was loved by ,jupiter1 and turned into a bear by the jealous ,juno4 ,among the old ,hindoos the seven stars represented the seven ,rishis4 ,it is the ,otawa of the great ,finnish epic1 the ,kalevala4 ,it was also called ,david's ,chariot1 and in ,america it is known as ,the ,dipper4 ,closely north of the star ,greek3 th in ,ursa ,major is a small star known as ,flamsteed #bf4 ,this is not mentioned by ,al-,sufi1 but is now1 ,i find from personal observation1 very visible1 and indeed conspicuous1 to the naked eye4 ,i find1 however1 that owing to the large proper motion of the bright star 7#aa per annum7 the two stars were much closer together in ,al-,sufi's time than they are at present1 and this probably accounts for ,al-,sufi's omission4 ,this is an interesting and curious fact1 and shows the small changes which occur in the heavens during the course of ages4 ,close to the star ,greek3 z1 the middle star of the tail of ,ursa ,major 7or handle of the ,plough71 is a small star known as ,alcor1 which is easily visible to good eyesight without optical aid4 ,it is mentioned by ,al-,sufi1 who says the ,arabians called it al-suha1 the little unnoticed one4 ,he says that ,ptolemy does not mention it1 and it is a star which seems to test the powers of the eyesight4 ,he adds1 however1 an ,arabian proverb1 ,i show him al-suha1 and he shows me the moon1 which seems to suggest that to some eyes1 at least1 it was no test of sight at all4 ,it has1 however1 been suspected of variation in light4 ,it was rated #eth magnitude by ,argelander1 ,heis1 and ,houzeau1 but was measured #djb at ,harvard ,observatory4 ,it has recently been found to be a spectroscopic binary4 ,the constellation of the ,dragon 7,draco7 is probably referred to in ,job 7chap4 xxvi4 v4 #ac71 where it is called the crooked serpent4 ,in the ,greek mythology it is supposed to represent the dragon which guarded the golden apples in the ,garden of the ,hesperides4 ,some have suggested that it represented the serpent which tempted ,eve4 ,dryden says1 in his translation of ,virgil-- ,around our ,pole the spiry ,dragon glides1 ,and like a wand'ring stream the ,bears divides4 ,the fact that the constellation ,botis rises quickly and sets slowly1 owing to its lying horizontally when rising and vertically when setting1 was noted by ,aratus1 who says-- ,the ,bearward now1 past seen1 ,but more obscured1 near the horizon lies2 ,for with the four ,signs the ,ploughman1 as he sinks1 ,the deep receives2 and when tired of day ,at even lingers more than half the night1 ,when with the sinking sun he likewise sets ,these nights from his late setting bear their name4#cig ,the cosmical setting of ,botis--that is1 when he sets at sunset--is stated by ,ovid to occur on ,march #e of each year4 ,with reference to the constellation ,hercules1 ,admiral ,smyth says-- ,the kneeling posture has given rise to momentous discussion2 and whether it represents ,lycaon lamenting his daughter's transformation1 or ,prometheus sentenced1 or ,ixion ditto1 or ,thamyrus mourning his broken fiddle1 remains still uncertain4 ,but in process of time1 this figure became a lion1 and ,hyginus mentions both the lion's skin and the club2 while the right foot's being just over the head of the ,dragon1 satisfied the mythologists that he was crushing the ,lernan hydra4444 ,some have considered the emblem as typifying the serpent which infested the vicinity of ,cape ,tnarus1 whence a sub-genus of ,ophidians still derives its name4 ,at all events a poet1 indignant at the heathen exaltation of ,hevelius1 has said-- ',to ,cerberus1 too1 a place is given-- ,his home of old was far from heaven4'#cih ,aratus speaks of ,hercules as the ,phantom whose name none can tell4 ,there were several heroes of the name of ,hercules1 but the most famous was ,hercules the ,theban1 son of ,jupiter and ,alcmene wife of ,amphitryon1 ,king of ,thebes1 who is said to have lived some years before the siege of ,troy1 and went on the voyage of the ,argonauts about #acjj ,b4,c4 ,according to some ancient writers1 another ,hercules lived about #bdjj ,b4,c41 and was a contemporary of ,atlas and ,theseus4 ,but according to ,ptau1 ,atlas lived about #afch ,b4,c41 and ,lalande thought that this chronology is the more probable4 ,the small constellation ,lyra1 which contains the bright star ,vega1 is called by ,al-,sufi the ,lyre1 the ,goose1 the ,persian harp1 and the ,tortoise4 ,in his translation of ,al-,sufi's work1 ,schjellerup suggests that the name ,goose may perhaps mean a plucked goose1 which somewhat resembles a ,greek lyre1 and also a tortoise4 ,the name of the bright star ,vega is a corruption of the ,arabic vki4 ,ptolemy and ,al-,sufi included all the very brightest stars in the first magnitude1 making no distinction between them1 but it is evident at a glance that several of them1 such as ,arcturus and ,vega1 are brighter than an average star of the first magnitude1 like ,aldebaran4 ,the constellation ,perseus1 which lies south-east of ,cassiopeia's ,chair1 may be recognized by the festoon formed by some of its stars1 the bright star ,greek3 a ,persei being among them4 ,it is called by ,al-,sufi barschnsch1 ,greek3 ,perseus1 ,perseus1 who is hamil rs al-gul1 the ,bearer of the head of al-gul4 ,according to ,kazimirski1 ,gul was a kind of demon or ogre who bewilders travellers and devours them1 beginning at the feet4 ,in general any mischievous demon capable of taking all sorts of forms4 ,in the ,greek mythology ,perseus was supposed to be the son of ,jupiter and ,dan4 ,he is said to have been cast into the sea with his mother and saved by ,king ,polydectus4 ,he afterwards cut off the head of ,medusa1 one of the ,gorgons1 while she slept1 and armed with this he delivered ,andromeda from the sea-monster4 ,the constellation ,auriga lies east of ,perseus and contains the bright star ,capella1 one of the three brightest stars in the northern hemisphere 7the others being ,arcturus and ,vega74 ,theon1 in his commentary on ,aratus1 says that ,bellerophon invented the chariot1 and that it is represented in the heavens by ,auriga1 the celestial coachman4 ,according to ,dupuis1 ,auriga represents ,phton1 who tried to drive the chariot of the sun1 and losing his head fell into the river ,eridanus4 ,the setting of ,eridanus precedes by a few minutes that of ,auriga1 which was called by some of the ancient writers ,amnis ,pha-tontis4#cii ,auriga is called by ,al-,sufi numsick al-ainna--,he who holds the reins1 the ,coachman2 also al-inz1 the ,she-goat4 ,m4 ,dorn found in ,ptolemy's work1 the ,greek name ,greek3 ,hniochoi1 ,auriga1 written in ,arabic characters4 ,al-,sufi says1 ,this constellation is represented by the figure of a standing man behind ',he who holds the head of al-gl' ,perseus1 and between the ,pleiades and the ,great ,bear4 ,capella is1 ,al-,sufi says1 the bright and great star of the first magnitude which is on the left shoulder of the ancient figure on the eastern edge of the ,milky ,way4 ,it is that which is marked on the astrolabe as al-aijk4 ,the real meaning of this name is unknown4 ,schjellerup thought1 contrary to what ,ideler says1 that the name is identical with the ,greek word ,greek3 ,aix 7a goat74 ,capella was observed at ,babylon about #bjjj ,b4,c41 and was then known as ,dilgan4 ,the ,assyrian name was ,icu1 and the ,persian name colca4 ,it was also called ,capra ,hircus1 ,cabrilla1 ,amalthea1 and ,olenia4 ,in ancient times the rising of ,capella was supposed to presage the approach of storms4 ,ovid says1 ,olenia sidus pluviale ,capell4 ,the constellation ,aquila is called by ,al-,sufi al-ukab1 the ,eagle1 or al-nasr al-tr1 the flying vulture4 ,according to the ancient poets the eagle carried nectar to ,jupiter when he was hidden in a cave in ,crete4 ,this eagle also assisted ,jupiter in his victory over the ,giants and contributed to his other pleasures4 ,for these reasons the eagle was consecrated to ,jupiter1 and was placed in the sky4 ,al-,sufi says1 ,there are in this figure three famous stars ,greek3 g1 ,greek3 a1 and ,greek3 b ,aquil1 which are called al-nasr al-tr4 ,hence is derived the modern name ,altair for the bright star ,greek3 a ,aquil4 ,al-,sufi says that the common people call the three famous stars al-mzn1 the ,balance1 on account of the equality of the stars4 ,this probably refers to the approximately equal distances between ,greek3 g and ,greek3 a1 and ,greek3 a and ,greek3 b1 and not to their relative brightness4 ,he says ,between the bright one of the tail ,greek3 x ,aquil and the star in the beak of the ,hen ,greek3 b ,cygni in the thinnest part of the ,milky ,way1 we see the figure of a little earthen jar1 of which the stars begin at the bright one in the tail1 and extend towards the north-west4 ,this seems to refer to ,greek3 e ,aquil and the small stars near it4 ,they then turn towards the east in the base of the jar1 and then towards the south-east to a little cloud #d1 #e1 etc4 ,vulpecul1 a well-known group of small stars which is found to the north of the two stars in the shaft of the ,arrow ,greek3 a and ,greek3 b ,sagitt4 ,the cloud is on the eastern edge of the jar1 and the bright one on the tail on the western edge2 the orifice is turned towards the flying ,vulture ,aquila1 and the base towards the north4 ,among these are distinguished some of the fourth1 fifth1 and sixth magnitudes including1 probably1 #aaj1 #aaa1 #aab1 #aac ,hercules1 and #a ,vulpecul and ,ptolemy says nothing of this figure1 except the bright star in the tail of the ,eagle 7see figure74 ,the above is a good example of the minute accuracy of detail in ,al-,sufi's description4 ,illustration3 ,,al-,,sufi',s ,,earthen ,,jar4 ,the southern portion of ,aquila was formerly called ,antinous1 who was said to have been a young man of great beauty born at ,claudiopolis in ,bithynia1 and drowned in the ,nile4 ,others say that he sacrificed his life to save that of the ,emperor ,hadrian1 who afterwards raised altars in his honour and placed his image on coins4#djj ,the constellation ,pegasus1 ,al-,sufi says1 is represented by the figure of a horse1 which has the head1 legs1 and forepart of the body to the end of the back1 but it has neither hind quarters nor hind legs4 ,according to ,brown1 ,pegasus was the horse of ,poseidon1 the sea god4 ,half of it was supposed to be hidden in the sea1 into which the river ,eridanus flowed4#dja ,in the ,greek mythology it was supposed to represent the winged horse produced by the blood which fell from the head of ,medusa when she was killed by ,perseus6 ,some think that it represents ,bellerophon's horse1 and others the horse of ,nimrod4 ,it was also called ,sagmaria and ,ephippiatus1 and was sometimes represented with a saddle instead of wings4 ,in describing the constellation ,andromeda1 ,al-,sufi speaks of two series of stars which start from the great nebula in ,andromeda2 one series going through #cb ,andromed1 ,greek3 p1 d1 and ,greek3 e to ,greek3 z and ,greek3 2 and the other through ,greek3 n1 m1 b ,andromed into the constellation ,pisces4 ,he says they enclose a fish-shaped figure called by the ,arabians al-ht1 the ,fish1 par excellence4 ,he speaks of two other series of stars which begin at ,greek3 t and ,greek3 u1 and diverging meet again at ,greek3 ch ,persei1 forming another fish-like figure4 ,the eastern stream starts from ,greek3 t and passes through #ee1 ,greek3 g1 #fj1 #fb1 #fd1 and #fe ,andromed2 and the western stream from ,greek3 u through ,greek3 ch #ea1 #ed1 and g ,persei up to ,greek3 ch ,persei4 ,the head of the first fish1 al-ht1 is turned towards the north1 and that of the second towards the south 7see figure74 ,illustration3 ,,al-,,sufi',s ,,fishes ,,in ,,andromeda4 ,al-,sufi says that the stars ,greek3 a ,persei1 ,greek3 g1 b1 d1 and ,greek3 a ,andromed1 and ,greek3 b ,pegasi form a curved line4 ,this is quite correct1 and this fine curve of bright stars may be seen at a glance on a clear night in ,september1 when all the stars are high in the sky4 ,the first constellation of the ,zodiac1 ,aries1 the ,ram1 was called1 according to ,aratus and ,eratosthenes1 ,greek3 krios4 ,it is mentioned by ,ovid under the name of ,hellas4 ,it was also called by the ancients the ,ram with the golden horns4 ,manilius 7fourth century ,b4,c47 called it ,the ,prince4 ,it is supposed to have represented the god ,bel4 ,among the ,accadians the sign meant ,he who dwells on the altar of uprightness4 ,it first appears on the ,egyptian ,zodiac2 and it was sacred to ,jupiter ,ammon4 ,in the ,greek mythology it was supposed to represent the ram1 the loss of whose fleece led to the voyage of the ,argonauts4 ,in the time of ,hipparchus1 about #bjjj years ago1 it was the first sign of the ,zodiac1 or that in which the sun is situated at the ,vernal ,equinox 7about ,march #ba in each year74 ,but owing to the precession of the equinoxes1 this point has now moved back into ,pisces4 ,the brightest star of ,aries 7,greek3 a7 is sometimes called ,hamal1 derived from the ,arabic al-hamal1 a name given to the constellation itself by ,al-,sufi4 ,in the ,accadian language it was called ,dilkur1 the dawn proclaimer4 ,ali-,sufi says that close to ,greek3 a1 as if it were attached to it1 is a small star of the #fth magnitude1 not mentioned by ,ptolemy4 ,this is clearly ,greek3 k ,arietis4 ,the fact of ,al-,sufi having seen and noticed this small star1 which modern measures show to be below the #eth magnitude1 is good evidence of his keen eyesight and accuracy of observation4 ,according to ,al-,sufi1 the stars ,greek3 b and ,greek3 g ,arietis were called by the ,arabians al-scharatain1 the two marks4 ,they marked the first mansion of the moon1 and ,greek3 e1 d1 and ,greek3 r the second mansion4 ,with reference to these so-called mansions of the moon1 ,admiral ,smyth says-- ,the famous ,manazil al-kamar1 i4e4 ,lunar mansions1 constituted a supposed broad circle in ,oriental astronomy divided into twenty-eight unequal parts1 corresponding with the moon's course1 and therefore called the abodes of the moon4 ,this was not a bad arrangement for a certain class of gazers1 since the luminary was observed to be in or near one or other of these parts1 or constellations every night4 ,though tampered with by astrologers1 these ,lunar mansions are probably the earliest step in ancient astronomy4#djb ,taurus1 the second constellation of the ,zodiac1 was in ancient times represented by the figure of a bull1 the hinder part of which is turned towards the south-west1 and the fore part towards the east4 ,it had no hind legs1 and the head was turned to one side1 with the horns extended towards the east4 ,its most ancient name was ,te1 possibly a corruption of the ,accadian dimmena1 a foundation-stone4 ,the ,greek name is ,greek3 athr 7,greek3 thr1 ,eusebius74 ,in the old ,egyptian mythology ,taurus represented the god ,apis4 ,according to ,dupuis it also represented the #ajth labour of ,hercules1 namely1 his victory over the cows of ,geryon1 ,king of ,spain4#djc ,it was also supposed to represent the bull under the form of which ,jupiter carried off ,europa1 daughter of ,agenor1 ,king of the ,phoenicians4 ,it may also refer to ,io or ,isis1 who is supposed to have taught the ancient ,egyptians the art of agriculture4 ,aldebaran is the well-known bright red star in the ,hyades4 ,it was called by ,ptolemy ,fulgur succularum4 ,ali-,sufi says it was marked on the old astrolabes as al-dabaran1 the ,follower 7because it follows the ,hyades in the diurnal motion71 and also ain al-tsaur1 the eye of the bull4 ,it may be considered as a standard star of the #ast magnitude4 ,modern observations show that it has a parallax of #jajg4 ,it is receding from the earth1 according to ,vogel1 at the rate of about #cj miles a second2 but even with this high velocity it will take thousands of years before its brightness is perceptibly diminished4 ,it has a faint companion of about the #ajth magnitude at the distance of #aah1 which forms a good light test for telescopes of #c or #d inches aperture4 ,i saw it well with a #d-;inch ,wray in the ,punjab sky4 ,the ,hyades were called ,succul by the ,romans1 and in the ,greek mythology were said to be children of ,atlas4 ,the star ,greek3 b ,tauri1 sometimes called ,nath1 from the ,arabic al-ntih1 the butting1 is a bright star between ,capella and ,greek3 g ,orionis 7,bellatrix74 ,it is on the tip of the horn in the ancient figure of ,taurus1 and therefore 7says ,admiral ,smyth7 at the greatest distance from the hoof2 can this have given rise to the otherwise pointless sarcasm of not knowing ,b from a bull's foot8#djd ,al-,sufi says that an imaginary line drawn from the star now known as ,a ,tauri to ,greek3 t ,tauri would pass between ,greek3 u and ,greek3 k ,tauri1 which is quite correct1 another proof of the accuracy of his observations4 ,he also says that the star ,greek3 ,tauri is exactly midway between ,a and ,greek3 e1 which is again correct4 ,he points out that ,ptolemy's position of ,greek3 is incorrect4 ,this is often the case with ,ptolemy's positions1 and tends to show that ,ptolemy adopted the position given by ,hipparchus without attempting to verify their position in the sky4 ,al-,sufi himself adopts the longitudes and latitudes of the stars as given by ,ptolemy in the ,almagest1 but corrects the positions in his descriptions1 when he found ,ptolemy's places erroneous4 ,the famous group of the ,pleiades is well known2 but there is great difficulty in understanding ,al-,sufi's description of the cluster4 ,he says1 ,the #bith star 7of ,taurus7 is the more northern of the anterior side of the ,pleiades themselves1 and the #cjth is the southern of the same side2 the #cast is the following vertex of the ,pleiades1 and is in the more narrow part4 ,the #cbnd is situated outside the northern side4 ,among these stars1 the #cbnd is of the #dth magnitude1 the others of the #eth4 ,now1 it is very difficult or impossible to identify these stars with the stars in the ,pleiades as they are at present4 ,the brightest of all1 ,alcyone 7,greek3 ,tauri71 now about #crd magnitude1 does not seem to be mentioned at all by ,al-,sufi6 as he says distinctly that the brightest star 7,no #cb of ,taurus7 is outside the ,pleiades on the northern side4 ,it seems impossible to suppose that ,al-,sufi could have overlooked ,alcyone had it the same brightness it has now4 ,the #cbnd star seems to have disappeared1 or at least diminished greatly in brightness1 since the days of ,al-,sufi4 ,more than four stars were1 however1 seen by ,al-,sufi1 for he adds1 ,it is true that the stars of the ,pleiades must exceed the four mentioned above1 but ,i limit myself to these four because they are very near each other and the largest that is1 the brightest2 this is why ,i have mentioned them1 neglecting the others4 ,a full examination of the whole question is given by ,flammarion in his interesting work ,les toiles 7pp4 #bhi-cjg71 and ,i must refer my readers to this investigation for further details4 ,according to ,brown1 ,simonides of ,keos 7,b4,c4 #eef-dfg7 says1 ,atlas was the sire of seven daughters with violet locks1 who are called the heavenly ,peleiades4#dje ,the name is by some supposed to be derived from the ,greek ,greek3 plein1 full4 ,the ,old ,testament word ,kimah 7,job ix4 #i and xxviii4 #ca7 and ,amos 7v4 #h7 is derived from the ,assyrian ,kimta1 a family4 ,aratus describes the ,pleiades in the following lines3-- ,near his#djf left thigh together sweep along ,the flock of ,clusterers4 ,not a mighty span ,holds all1 and they themselves are dim to see1 ,and seven paths aloft men say they take1 ,yet six alone are viewed by mortal eye4 ,these seven are called by name ,alkyon ,kelain1 ,merop and ,sterop ,tayget1 ,elecktr1 ,maia queen4 ,they thus together small and faint roll on ,yet notable at morn and eve through ,zeus4#djg ,the ,pleiades are mentioned by ,ovid4 ,according to the ancient poets they were supposed to represent the children of ,atlas and ,hesperus1 and on this account they were called ,atlantids or ,hesperides4 ,from the resemblance in sound to the word ,greek3 pleias1 a pigeon1 they were sometimes called the doves1 and for the same reason the word ,greek3 plein1 to navigate1 led to their being called the shipping stars4 ,the word ,greek3 pleias was also applied to the priestesses of the god ,zeus 7,jupiter7 at ,dordona1 in the groves of which temple there were a number of pigeons4 ,this is1 perhaps1 what ,aratus refers to in the last line of the extract quoted above4 ,according to ,neapolitan legends1 the name of ,virgil's mother was ,maia4 ,the mother of ,buddha1 the ,hindoo avatar1 was also named ,maia4 ,in ,italy the ,pleiades were called ,gallinata1 and in ,france poussinire1 both of which mean the hen and chickens1 a term also given to them by ,al-,sufi4 ,the old ,blackfoot ,indians called them ,the ,seven ,perfect ,ones4 ,the ,crees and ,ojibway ,indians called them the ,fisher ,stars4 ,the ,adipones of ,brazil and some other nations claimed that they sprang from the ,pleiades6 ,the ,wyandot ,indians called them ,the ,singing ,maidens4 ,photographs show that the brighter stars of the ,pleiades are involved in nebulosity4 ,that surrounding ,maia seems to be of a spiral form4 ,now1 there is a ,sanscrit myth which represents ,maia as weaving the palpable universe1 for which reason she was typified as a spider4 ,this seems very appropriate1 considering the web of nebulous light which surrounds the stars of the group4 ,maia was also considered as a type of the universe1 which again seems appropriate1 as probably most of the stars were evolved from spiral nebul4 ,the name ,hyades is supposed to be derived from the ,greek word ,greek3 hyein1 to rain1 because in ancient times they rose at the rainy season4 ,in ancient ,egypt1 ,aldebaran was called ary2 and the ,pleiades chooa1 a word which means thousands4 ,the name ,aldebaran seems to have been originally applied to the whole of the ,hyades group4 ,aldebaran was also called by the ,arabians al-fanik1 the great ,camel1 and the ,hyades al-kilas1 the young ,camels4 ,the two close stars ,greek3 u and ,greek3 k ,tauri were called al-kalban1 the dogs of ,aldebaran4 ,la ,condamine states that the ,indians of the ,amazon saw in the ,hyades the head of a bull4 ,gemini1 the ,twins1 is the third constellation of the ,zodiac4 ,it was also called ,gemelli1 etc4 ,according to ,dupuis it represents the #aath labour of ,hercules--his triumph over the dog ,cerberus4#djh ,but some of ,dupuis' ideas seem very fanciful4 ,the ,twins are usually called ,castor and ,pollux1 but they were also called by the ancient writers ,apollo and ,hercules2 ,jason and ,triptolemus2 ,amphion and ,zethus2 and ,theseus and ,peritheus4 ,in ,egypt they represented the deities ,horus and ,hippocrates4 ,brown thinks that the ,great ,twins were originally the sun and moon1 who live alternately4 ,as one is born the other dies2 as one rises the other sets4#dji ,this applies to the full moon1 but does not seem applicable to the other lunar phases4 ,gemini was the constellation to which ,dante supposed himself transported when he visited the stellar heavens4#daj ,he says he was born under the influence of this sign4 ,cancer1 the ,crab1 is the next sign of the ,zodiac4 ,in the ,greek mythology it was supposed to have been placed in the sky by ,juno to commemorate the crab which pinched the toes of ,hercules in the ,lernan marsh4 ,the ,greek name was ,greek3 tybi4 ,according to ,dupuis it represents the #abth labour of ,hercules--his capture of the golden apples in the ,garden of the ,hesperides1 which were guarded by a ,dragon4 ,this ,dragon is ,draco1 which was also called ,custos ,hesperidum4#daa ,but the connection between a crab and the myth of the golden apples is not obvious--unless some reference to crab apples is intended6 ,among the ,romans1 ,cancer was consecrated to ,mercury1 and by the ancient ,egyptians to their god ,anubis4 ,the well-known cluster in ,cancer called the ,prsape1 ,al-,sufi says1 is a little spot which resembles a cloud1 and is surrounded by four stars1 two to the west ,greek3 and ,greek3 th ,cancri and two to the east ,greek3 g and ,greek3 d4 ,this cluster is mentioned by ,aratus1 who calls it the ,manger4 ,the word ,prsape is often translated ,beehive1 but there can be no doubt that it really means ,manger1 referring to the stars ,greek3 g and ,greek3 d ,cancri1 which the ancients called ,aselli1 the ass's colts4 ,these were supposed to represent the asses which in the war of ,jupiter against the ,giants helped his victory by their braying6 ,admiral ,smyth says in his ,bedford ,catalogue 7p4 #bjb7 that he found ,greek3 g and ,greek3 d ,cancri both of #dth magnitude2 but the photometric measures show that ,greek3 d is now distinctly brighter than ,greek3 g4 ,an occultation of ,greek3 d ,cancri by the moon is recorded as having occurred on ,september #c1 ,b4,c4 #bdj4 ,the fine constellation ,leo1 the ,lion1 is the next sign of the ,zodiac1 and is marked by the well-known ,sickle4 ,according to ,dupuis1 it represents the first labour of ,hercules--the killing of the ,nemlian lion4 ,manilius called it ,nemus4 ,it was also called ,janonus sidus1 ,bacchi sidus1 etc4 ,the ,greek name was ,greek3 mechir1 ,greek3 mecheir1 or ,greek3 mechos4 ,in ancient ,egypt1 ,leo was sacred to ,osiris1 and many of the ,egyptian monuments are ornamented with lions' heads4 ,it is stated in the ,horapolla that its appearance was supposed to announce the annual rising of the ,nile4 ,regulus 7,greek3 a ,leonis7 is the brightest and most southern of the stars in the ,sickle4 ,al-,sufi says it is situated in the heart and is of the #ast magnitude4 ,it is that which is called al-maliki1 the royal star4 ,it is marked on the astrolabe as kalb al-asad1 the ,heart of the ,lion 7whence the name ,cor ,leonis74 ,modern photometric measures make it about #ac magnitude4 ,it has an #h-a_/b magnitude companion at about #agg distance 7,burnham7 which is moving through space with the bright star1 and is therefore at probably the same distance from the earth as its brilliant primary4 ,this companion is double 7#he1 #abe3 #cje1 ,burnham74 ,the spectroscope shows that ,regulus is approaching the earth at the rate of #e-a_/b miles a second4 ,its parallax is very small--about #jjbb1 according to ,dr4 ,elkin--which indicates that it is at a vast distance from the earth2 and its brightness shows that it must be a sun of enormous size4 ,ptolemy called it ,greek3 basiliskos1 whence its ,latin name ,regulus1 first used by ,copernicus as the diminutive of rex4#dab ,the next constellation of the ,zodiac is ,virgo1 the ,virgin4 ,it was also called by the ancients ,ceres1 ,isis1 ,erigone1 ,fortuna1 ,concorda1 ,astra1 and ,themis4 ,the ,greek name was ,greek3 phamenth4 ,ceres was the goddess of the harvest4 ,brown thinks that it probably represents the ancient goddess ,istar1 and also ,ashtoreth4 ,according to ,prof4 ,sayce it is the same as the ,accadian sign of the errand of ,istar1 a name due to the belief that it was in ,august that the goddess ,astarte descended into ,hades in search of her betrothed1 the sun god ,tammuz1 or ,adonis1 who had been slain by the boar's tusk4#dac ,the ear of corn 7,spica7 is found on the ancient ,egyptian monuments1 and is supposed to represent the fertility caused by the annual rising of the ,nile4 ,according to ,aratus1 the ,virgin lived on earth during the golden age under the name of ,justice1 but that in the bronze age she left the earth and took up her abode in the heavens4 ,justice1 loathing that race of men1 ,winged her flight to heaven4 ,the ,sphinx near the ,great ,pyramid has the head of a virgin on the body of a lion1 representing the goddess ,isis 7,virgo7 and her husband ,osiris 7,leo74 ,al-,sufi's #eth star of ,virgo is ,flamsteed #fc ,virginis4 ,al-,sufi says it is a double star of the #eth magnitude4 ,in ,al-,sufi's time it formed a naked-eye double with #fa ,virginis1 but owing to large proper motion1 #fa has now moved about #bf minutes of arc towards the south1 and no longer forms a double with #fc4 ,this interesting fact was first pointed out by ,flammarion in his work ,les toiles 7p4 #cgc74 ,libra1 the ,balance1 is one of the signs of the ,zodiac1 but originally formed the claws of the ,scorpion4 ,it was called ,juguna by ,cicero1 and ,mochos by ,ampelius4 ,the ,greek name was ,greek3 pharmouthe4 ,virgil suggests that it represented the justice of the emperor ,augustus1 honoured by the name of a constellation2 but probably this refers to the birth of ,augustus under the sign of ,libra1 as ,scaliger has pointed out4 ,according to ,brown1 the daily seizing of the dying western sun by the claws of the ,scorpion of darkness is reduplicated annually at the ,autumnal ,equinox1 when the feeble waning sun of shortening days falls ever earlier into his enemy's grasp2#dad and he says1 ,the ,balance or ,scales 7,libra71 which it will be observed is in itself neither diurnal nor nocturnal1 is the only one of the zodiacal signs not ,euphratean in origin1 having been imported from ,egypt and representing originally the balance of the sun at the horizon between the upper and under worlds2 and secondarily the equality of the days and nights at the equinox4#dae ,according to ,houzeau1 ,libra was formed at the beginning of the second century ,b4,c41 and it does not appear in any writings before those of ,geminus and ,varron4#daf ,milton says in ,paradise ,lost3-- ,the ,eternal to prevent such horrid fray1 ,hung forth in heaven his golden scales1 yet seen ,betwixt ,astra and the ,scorpion's sign4 7,here ,astra is ,virgo47 ,it is worth noticing that both ,ptolemy and ,al-,sufi rated the star ,greek3 k ,libr as two magnitudes brighter than ,greek3 l ,libr4 ,the two stars are now practically of equal brightness 7#eth magnitude71 and it seems impossible to believe that this could have been the case in ,al-,sufi's time4 ,surely a careful observer like ,al-,sufi1 who estimated the relative brightness of stars to a third of a magnitude1 could not possibly have made an error of two magnitudes in the brightness of two stars near each other6 ,it should be stated1 however1 that ,greek3 k ,libr was rated #eth magnitude by ,argelander and ,heis1 and ,greek3 l1 #fth magnitude by the same excellent observers4 ,the next sign of the ,zodiac1 ,scorpion1 was consecrated by the ,romans to ,mars1 and by the ,egyptians to ,typhon4#dag ,it was called ,nepa by ,cicero1 ,martis sidus by ,manilius1 and ,fera magna by ,aratus4 ,the ,greek name was ,greek3 pachn4 ,mr4 ,e4 ,b4 ,knobel has called attention to a curious remark of ,ptolemy with reference to the bright star ,antares 7,greek3 a ,scorpii71 ,media earum qu tendit ad rapinam qu dicitur ,cor ,scorpionis2 and he made a similar remark with reference to ,betelgeuse 7,greek3 a ,orionis7 and others4 ,but ,mr4 ,robert ,brown#dah explains the remark by the fact that in ancient times these stars rose in the morning at a time when caravans were exposed to dangers from robbers4 ,thus the term had nothing to do with the aspect or colour of these stars1 but was merely a reference to their supposed astrological influence on human affairs4 ,in the ,egyptian ,book of the ,dead1 ,silkit was a goddess who assumed the form of a scorpion in the sky4 ,she was supposed to be the daughter of ,ra4 ,with reference to stars outside the ancient figure of ,scorpio1 the first1 ,al-,sufi says1 is a star which immediately follows al-schaulat ,greek3 l and ,greek3 k1 it is of small #dth magnitude2 ,ptolemy calls it ,greek3 nepheloeids nebulous4 ,schjelerup1 in his translation of ,al-,sufi's work1 does not identify this object2 but it is very evidently ,greek3 g ,telescopii1 which lies exactly in the position described by ,al-,sufi4 ,now1 it is a very interesting and curious fact that ,ptolemy called it nebulous1 for in the same telescopic field with it is the nebula h #cgje 7 ,dunlop #eeg74 ,dunlop describes it as a small well-defined rather bright nebula1 about #bj in diameter2 a very small star precedes it1 but is not involved2 following ,greek3 g ,telescopii4 ,sir ,john ,herschel at the ,cape found it fairly resolved into very faint stars1 and adds1 ,the whole ground of the heavens1 for an immense extent is thickly sown with such stars4 ,a beautiful object4#dai ,this perhaps accounts for the nebulous appearance of the star as seen by ,ptolemy4 ,several nov or temporary stars are recorded as having appeared in ,scorpio4 ,one in the year ,b4,c4 #acd is stated by ,pliny to have induced ,hipparchus to form his catalogue of stars4 ,this star was also observed in ,china4 ,its exact position is unknown1 but ,flammarion thinks it may possibly have appeared about #d north of the star ,greek3 b ,scorpii4 ,another new star is said to have appeared in ,a4,d4 #cic1 somewhere in the ,scorpion's tail4 ,one in ,a4,d4 #abjc and another in #aehd are also mentioned1 the latter near ,greek3 p ,scorpii4 ,the constellation ,scorpio seems to be referred to by ,dante in his ,purgatorio 7ix4 #d-f7 in the lines-- ,de gemma la sua fronte era lucenta ,poste in figura del fredda animale ,che con la coda percota la genta1 perhaps suggested by ,ovid's remark-- ,scorpius exhibit caudaque menabitur unca4#dbj ,next to ,scorpio comes ,sagittarius1 the ,archer4 ,it is said to have been placed in the sky as a symbol of ,hercules1 a hero who was held in the greatest veneration by the ancient ,egyptians4 ,the horse1 usually associated with this constellation1 was a symbol of war4 ,it was also called by the ancients ,chiron1 ,arcitenens1 ,minotaurus1 ,croton1 etc4 ,the ,greek name was ,greek3 pauni1 or ,greek3 pani4 ,chiron was supposed to be the son of ,saturn and ,phillyra1 and first taught men to ride on horses4 ,the name is derived from the ,greek ,greek3 cheir1 a hand4 ,some writers1 however1 think that ,chiron is represented by the constellation of the ,centaur1 and others say that ,sagittarius represents the ,minotaur loved by ,persephone4 ,according to ,dupuis1 ,sagittarius represents the #eth labour of ,hercules1 which consisted in hunting the birds of the lake ,stymphalus1 which ravaged the neighbouring countries4 ,these birds are perhaps represented by ,cygnus1 ,altair1 and the ,vulture 7,lyra74 ,the ,lyre probably represents the musical instrument which ,hercules used to frighten the birds4#dba ,according to ,al-,sufi1 the ,arabians called the stars ,greek3 g1 d1 e1 and ,greek3 ,sagittarii which form a quadrilateral figure1 the ,ostrich which goes to the watering place1 because they compared the ,milky ,way to a river4 ,they compared the stars ,greek3 s1 ph1 t1 and ,greek3 z ,sagittarii1 which form another quadrilateral1 to an ostrich which has drunk and returns from the watering place4 ,he says that the star ,greek3 l ,sagittarii forms with these two ostriches a tent1 and certainly the figure formed by ,greek3 l1 ph1 z1 e1 and ,greek3 d is not unlike a tent4 ,al-,sufi says more about these ostriches2 but the ideas of the old ,arabians about the stars seem very fanciful4 ,a temporary star is recorded in the ,chinese ,annals of ,ma-touan-lin as having appeared in ,may1 ,b4,c4 #dh1 about #d distant from ,greek3 m ,sagittarii4 ,another in the year #ajaa ,a4,d4 appeared near the quadrilateral figure formed by the stars ,greek3 s1 t1 z1 and ,greek3 ph ,sagittarii4 ,this may perhaps be identified with the object referred to by ,hepidannus in the year #ajab1 which was of extraordinary brilliancy1 and remained visible in the southern part of the heavens during three months4 ,another is mentioned near the same place in ,a4,d4 #chf 7,april to ,july74#dbb ,the number of temporary stars recorded in this part of the heavens is very remarkable4 ,according to ,brown1 ,sagittarius is depicted on a stone1 cir4 ,b4,c4 #aajj1 found at ,bbilu1 and now in the ,british ,museum4#dbc 99 99 99 99 99 ,the next of the signs of the ,zodiac is ,capricornus1 the ,goat4 ,in the ,arabo-,latin edition of ,ptolemy's ,almagest it is called ,alcaucurus4 ,it is supposed to represent ,amalthea1 the goat which nursed ,jupiter4 ,according to ,dupuis it represented the #fth labour of ,hercules1 which was the cleaning out of the ,augean stables4#dbd ,greek3 a#b ,capricorni is the northern of two stars of the #dth magnitude 7,greek3 a and ,greek3 b ,capricorni74 ,it really consists of two stars visible to the naked eye4 ,the second of these two stars 7,greek3 a#a7 is not mentioned by ,al-,sufi1 but ,i find that1 owing to proper motion1 they were nearer together in his time 7tenth century71 and were evidently seen by him as one star4 ,greek3 b ,capricorni 7about #crd magnitude7 is a very wide double star 7#c-a_/b1 #f2 #bje71 which may be seen with any small telescope4 ,the fainter star was found to be a close double by ,burnham4 ,at present ,greek3 b is brighter than ,greek3 a1 although rated of the same brightness by ,al-,sufi4 ,aquarius is the next sign of the ,zodiac4 ,it is supposed to represent a man pouring water out of an urn or bucket4 ,other names given to this constellation were ,aristus1 ,ganymede1 ,cecrops1 ,amphora1 ,urna1 and ,aqua tyrannus4 ,according to ,dupuis it represents the #gth labour of ,hercules1 which was his victory over the famous bull which ravaged ,crete4#dbe ,but the connection between a bull and a bucket is not obvious4 ,aquarius is represented in several places on the ,egyptian monuments4 ,some of the ancient poets supposed that it represented ,deucalion 7the ,noah of the ,greek story of the ,deluge72 others thought that it represented ,cecrops1 who came to ,greece from ,egypt1 built ,athens1 and was also called ,bifornis4 ,others say that he was ,ganymede1 the cup-bearer of the gods4 ,there is some difficulty about the identification of some of ,al-,sufi's stars in ,aquarius4 ,his sixth star 7,fl4 #g7 is nearly #aj south-west of ,greek3 b ,aquarii1 and is1 ,al-,sufi says1 the following of three stars in the left hand1 and precedes the fourth ,greek3 b 444 it is of the #fth magnitude4 ,ptolemy calls it third1 but in reality it is very faint now about #fth magnitude4 ,the seventh ,greek3 m is the middle one of the three and about #d-a_/b magnitude1 although ,al-,sufi calls it small fifth ,ptolemy rated it #d4 ,the eighth star1 ,greek3 e1 is the preceding of the three and about #ch1 agreeing closely with ,al-,sufi's #dc4 ,ptolemy rated it #c4 ,this star is mentioned under the name nou in the time of ,tcheou-,kong in the twelfth century ,b4,c4 ,al-,sufi says1 ,these three stars are followed by a star of the #eth magnitude which ,ptolemy has not mentioned4 ,it is brighter than the sixth star ,fl4 #g4 ,this is evidently ,greek3 n ,aquarii4 ,if1 however1 we plot ,ptolemy's positions as given by ,al-,sufi1 it seems probable that ,ptolemy's sixth star was really ,greek3 n1 and that either ,greek3 m or ,fl4 #g was not seen by him4 ,as ,ptolemy called his seventh star #dth magnitude1 and his sixth and eighth stars #crd magnitude1 some considerable change of brightness seems to have taken place in these stars2 as ,greek3 n is now only #d-a_/b and ,fl4 #g only a bright sixth4 ,variation was suspected in ,fl4 #gdbf by ,gould4 ,i found it very reddish with binocular in ,october1 #ahib4 ,burnham found it to be a close double star1 the companion being about #abth magnitude at a distance of only #b4 ,it is probably a binary4 ,according to ,al-,sufi1 the ,arabians called the second and third stars of the figure 7,greek3 a and ,greek3 o ,aquarii7 sad al-malik 7malk or mulk71 the ,good ,fortune of the king4 ,they called the fourth and fifth stars 7,greek3 b and ,greek3 x ,aquarii7 with the twenty-eighth star of ,capricornus 7c7 sad al-sund1 the ,good ,fortune of the ,happy ,events4 ,this is the #bdth mansion of the moon4 ,these stars rose at the time of year when the cold ends1 and they set at the time the heat ends4 ,hence1 ,al-,sufi says1 when they rise the rains begin1 and when they set the unhealthy winds cease1 fertility abounds1 and the dew falls4 ,hence probably the ,arabic names4 ,this1 of course1 applies to the climate of ,persia and ,arabia1 and not to the ,british ,isles4 ,al-,sufi says1 ,they call the #fth1 #gth1 and #hth stars sad bula1 ',the ,good ,fortune which swallows up6' ,this is the #bcrd mansion of the moon4 ,they say that it is so called because that at the time of the ,deluge it rose at the moment when ,god said1 ',o earth6 absorb the waters' 7,koran1 chap1 xi41 v4 #df74 ,they called the stars ,greek3 g1 p1 z and ,greek3 ,aquarii sad al-achbija1 'the the ,good ,fortune of the tents'2 this is the #beth mansion of the moon1 and they give them this name because of these four stars1 three form a triangle1 the fourth ,greek3 z being in the middle4 ,the three were considered to form a tent4 ,the ,arabians called the bright star ,fomalhaut in the mouth of the southern fish al-dhifda al-auval1 'the first ,frog1' as the bright one on the southern point of the tail of ,ktus ,cetus is called al-dhifda al-tsani ,greek3 b ,ceti1 'the second ,frog4' ,fomalhaut was also called al-zhalim1 the male ostrich4 ,al-,sufi says1 ,some of the ,arabians state that a ship is situated to the south of ,aquarius4 ,the stars in the ,southern ,fish 7,piscis ,australis7 seem to be here referred to4 ,the constellation ,pisces1 the ,fishes1 is the last of the signs of the ,zodiac4 ,the ,fishes appear on an ancient ,greek obelisk described by ,pococke4 ,among the ,greeks this sign was consecrated to ,venus2 and in ,egypt to ,nepthys1 wife of ,typhon and goddess of the sea4 ,pisces is said to end the ,zodiac as the ,mediterranean ,sea terminated ,egypt4 ,this idea was suggested by ,schmidt1 who also conjectured that the ,ram 7,aries7 was placed at the beginning of the ,zodiac because ,thebes1 a town sacred to ,jupiter ,ammon1 was at the beginning of ,egypt in ancient times2 and he thought that the constellation ,triangulum1 the ,triangle1 represented the ,nile ,delta1 ,eridanus being the ,nile4#dbg ,the constellation was represented in ancient times by two fishes connected by a cord tied to their tails4 ,the southern of these fishes lies south of the ,square of ,pegasus1 and the northern between ,andromeda and ,aries4 ,according to ,manilius1 the origin of these fishes is as follows3 ,venus1 seeing ,typhon on the banks of the river ,euphrates1 cast herself with her son into the river and they were transformed into fishes6 ,some of the ,arabians substituted a swallow for the northern of the two fishes--the one below ,andromeda4 ,the swallow was a symbol of ,spring4 ,according to ,dupuis1 ,pisces represents the #hth labour of ,hercules1 his triumph over the mares of ,diomed which emitted fire from their nostrils4#dbh ,but the connection between fishes and mares is not obvious1 and some of ,dupuis' ideas seem very fanciful4 ,here he seems to have found a mare's nest4 ,the constellation ,cetus1 the ,whale1 represents1 according to ancient writers1 the sea monster sent by ,neptune to devour ,andromeda when she was chained to the rock4 ,aratus calls ,cetus the dusky monster1 and ,brown remarks that the ',dusky ,star' would be peculiarly appropriate to ,mira 7the wondrous ,greek3 o ,ceti74#dbi ,cetus was also called ,canis ,tritonis1 or ,dog of the ,sea1 ,bayer in his ,atlas 7#afjc7 shows a dragon instead of a whale1 finding it so represented on some ancient spheres4 ,al-,sufi calls it ,ktus or ,greek3 ktos1 the whale4 ,he says1 it is represented by the figure of a marine animal1 of which the fore part is turned towards the east1 to the south of the ,ram1 and the hinder part towards the west behind the three 'extern' stars of ,aquarius4 ,al-,sufi does not mention the variable star ,greek3 o ,ceti1 now called ,mira1 or the wonderful1 nor does he refer to any star in its immediate vicinity4 ,we may1 therefore1 conclude that it was near a minimum of light at the time of his observation of the stars of ,cetus4 ,the constellation of ,orion1 one of the finest in the heavens1 was called by ,al-,sufi al-djabbar1 the ,giant1 and also al-djauza1 the ,spouse4 ,the poet ,longfellow says-- ,sirius was rising in the east ,and1 slow ascending one by one1 ,the kindling constellations shone ,begirt with many a blazing star ,stood the great giant ,al-gebar ,orion1 hunter of the beast6 ,his sword hung gleaming at his side ,and on his arm1 the lion's hide-- ,scattered across the midnight air ,the golden radiance of its hair4 ,al-,sufi says it is represented by the figure of a standing man1 to the south of the sun's path4 ,this constellation very much resembles a human figure with a head and two shoulders4 ,it is called al-djabbar1 'the ,giant1' because it has two thrones1 holds a club in his hand1 and is girded with a sword4 ,orion is supposed to have been a son of ,neptune2 but there are many stories of the origin of the name4 ,it is also said to be derived from the ,greek word ,greek3 ra1 because the constellation was used to mark the different times of the year4 ,according to the ancient fable1 ,orion was killed by a scorpion1 and was placed in the sky at the request of ,diana4 ,according to ,houzeau1 the name comes from oriri1 to be born4 ,scorpio rises when ,orion sets1 and he thinks that the idea of the ancients was that the ,scorpion in this way kills the giant ,orion4 ,in ancient ,egypt ,orion was called ,sahu4 ,this name occurs on the monuments of the ,ptolemies1 and also on those of the ,pharaohs4 ,it is also mentioned in the ,book of the ,dead4 ,it seems to have been considered of great importance in ancient ,egypt1 as its heliacal rising announced that of ,sirius1 which heralded the annual rising of the ,nile4 ,the constellation ,eridanus lies south of ,taurus1 east of ,cetus1 and west of ,lepus4 ,in ancient times it was supposed to represent the ,nile or the ,po4 ,ptolemy merely calls it ,greek3 ,potamou asterismos1 or asterism of the river4 ,it was called ,eridanus by the ,greeks1 and ,fluvius by the ,romans4 ,it appears to correspond with the ,hebrew ,shicor4 ,al-,sufi calls it al-nahr1 the ,river4 ,one of the most interesting points in ,al-,sufi's most interesting work is the identity of the bright star known to the ancient astronomers as achir al-nahr1 the ,end of the ,river1 and called by ,ptolemy ,greek3 ,eschatos tou potamou1 the ,last in the ,river4 ,some astronomers have identified this star with ,greek3 a ,eridani 7,achernar71 a bright southern star of the #ast magnitude1 south of ,eridanus4 ,but ,al-,sufi's description shows clearly that the star he refers to is really ,greek3 th ,eridani2 and the reader will find it interesting to follow his description with a star map before him4 ,describing ,ptolemy's #cdth star of ,eridanus 7the star in question71 he says1 the #cdth star is found before that is west of these three stars the #cast1 #cbnd1 and #ccrd1 which are ,greek3 u#b1 ,du1 and ,greek3 u' in ,proctor's ,atlas1 the distance between it and that of the three which is nearest being about #d cubits #i #bj'4 ,it is of the first magnitude2 it is that which is marked on the southern astrolabe1 and called achir al-nahr1 'the ,end of the ,river4' ,there are before this bright one two stars1 one to the south1 ,greek3 s ,eridani1 not shown in ,proctor's small ,atlas1 the other to the north ,greek3 i ,eridani2 ,ptolemy does not mention these4 ,one of these stars is of the #dth magnitude1 the other of the #eth4 ,there is behind the same that is1 east of it a star of the #dth magnitude distant from it two cubits ,greek3 e ,eridani4 ,to the south of the three stars which follow the bright one there are some stars of the #dth and #eth magnitudes1 which he ,ptolemy has not mentioned4 ,now1 a glance at a star map of this region will show clearly that the bright star referred to by ,al-,sufi is undoubtedly ,greek3 th ,eridani1 which is therefore the star known to the ancients as the ,end of the ,river1 or the ,last in the ,river4 ,the position given by ,ptolemy agrees fairly well with ,al-,sufi's description1 although the place is slightly erroneous1 as is also the case with ,fomalhaut and ,greek3 b ,centauri4 ,it is impossible to suppose that either ,ptolemy or ,al-,sufi could have seen ,greek3 a ,eridani1 as it is too far south to be visible from their stations1 and1 owing to the precession of the equinoxes1 the star was still further south in ancient times4 ,al-,sufi says distinctly that the distance between ,ptolemy's #ccrd star 7which is undoubtedly h ,eridani1 or ,proctor's ,greek3 u'7 and the #cdth star was #d cubits1 or #i #bj'4 ,the actual distance is about #i #aa'1 so that ,al-,sufi's estimate was practically correct4 ,halley1 in his ,catalogus ,stellarium ,australium1 identifies ,ptolemy's star with ,greek3 th ,eridani1 and ,baily agreed with him4#dcj ,ulugh ,beigh also identifies the ,last in the ,river with ,greek3 th ,eridani4 ,the ,arabic observer ,mohammed ,ali ,achsasi1 who observed in the seventeenth century1 called ,greek3 th ,eridani ,achr al-nahr1 and rated it first magnitude4#dca ,to argue1 as ,bode and ,flammarion have done1 that ,ptolemy and ,al-,sufi may have heard of ,greek3 a ,eridani from travellers in the southern hemisphere1 is to beg the whole question at issue4 ,this is especially true with reference to ,al-,sufi1 who says1 in the preface to his work1 that he has described the stars as seen with my own eyes4 ,greek3 a ,eridani is over #aa cubits from h ,eridani instead of #d cubits as ,al-,sufi says4 ,this shows conclusively that the star seen by ,al-,sufi was certainly not ,greek3 a ,eridani4 ,the interest of the identification is that ,al-,sufi rated ,greek3 th ,eridani of the first magnitude1 whereas it is now only #crd magnitude6 ,it was measured #cjf at ,harvard and estimated #cd by ,stanley ,williams1 so that it has evidently diminished greatly in brightness since ,al-,sufi's time4 ,there is an interesting paper on this subject by ,dr4 ,anderson 7the discoverer of ,nova ,aurig and ,nova ,persei7 in ,knowledge for ,july1 #ahic1 in which he states that the ,last in the ,river1 according to the statements of ,hipparchus and ,ptolemy1 did rise above their horizon at a certain time of the year1 which ,greek3 a ,eridani could not possibly have done4 ,this seems sufficient to settle the question in favour of ,greek3 th ,eridani4 ,dr4 ,anderson says1 ,it is much to be regretted that ,professor ,schjellerup1 the able and industrious translator of ,sufi1 has allowed this to escape his notice1 and helped in the preface and note to his work to propagate the delusion that ,greek3 a ,eridani is ,ptolemy's ',last in the ,river'2 and in this opinion ,i fully concur4 ,al-,sufi's clear account places it beyond a doubt that the star known to ,hipparchus1 ,ptolemy1 ,al-,sufi1 and ,ulugh ,beigh as the ,last in the ,river was ,greek3 th ,eridani4 ,greek3 th must have diminished greatly in brightness since ,al-,sufi's time1 for in ranking it as #ast magnitude he placed it in a very select list4 ,he only rated thirteen stars in the whole heavens as being of the #ast magnitude4 ,these are3 ,arcturus1 ,vega1 ,capella1 ,aldebaran1 ,regulus1 ,greek3 b ,leonis1 ,fomalhaut1 ,rigel1 ,greek3 th ,eridani1 ,sirius1 ,procyon1 ,canopus1 and ,greek3 a ,centauri4 ,all these stars were actually seen by ,al-,sufi1 and described from his own observations4 ,he does not mention ,greek3 a ,eridani1 as it was not visible from his station in ,persia4 ,greek3 th ,eridani is a splendid double star 7#cdj1 #ddi3 #hch1 #aijb1 ,tebbutt74 ,i found the components white and light yellow with #c-;inch refractor in the ,punjab4 ,dr4 ,gould thinks that one of the components is variable to some extent4 ,this is interesting1 considering the brilliancy of the star in ,al-,sufi's time4 ,the brighter component was found to be a spectroscopic binary by ,wright1 so that on the whole the star is a most interesting object4 ,the small constellation ,lepus1 the ,hare1 lies south of ,orion4 ,pliny calls it ,dasypus1 and ,virgil ,auritus4 ,in ancient ,egypt it was the symbol of vigilance1 prudence1 fear1 solitude1 and speed4#dcb ,it may perhaps represent the hare hunted by ,orion2 but some say it was placed in the sky to commemorate a terrible plague of hares which occurred in ,sicily in ancient times4 ,a little north-west of the star ,greek3 m ,leporis is ,hind's crimson star 7,r4,a4 #d;h #ecm1 ,s4 #ad #eg'1 #aijj7 described by him as of the most intense crimson1 resembling a blood drop on the background of the sky2 as regards depth of colour1 no other star visible in these latitudes could be compared with it4 ,it is variable from about the #fth to the #hth magnitude1 with a period of about #dcf days from maximum to maximum4 ,the constellation ,canis ,major1 the ,great ,dog1 is remarkable for containing ,sirius1 the brightest star in the heavens4 ,in the ,greek mythology it was supposed to represent a dog given by ,aurora to ,cephalus as the swiftest of all dogs4 ,cephalus wished to match it against a fox which he thought surpassed all animals for speed4 ,they both ran for so long a time1 so the story goes1 that ,jupiter rewarded the dog by placing it among the stars4 ,but probably the dog comes from ,anubis1 the dog-headed god of the ancient ,egyptians4 ,according to ,brown1 ,theogirius 7,b4,c4 #edd7 refers to the constellation of the ,dog4#dcc ,he thinks that ,canis ,major is probably a reduplication of ,orion2 ,sirius and ,greek3 b ,canis ,majoris corresponding to ,greek3 a and ,greek3 g ,orionis2 ,greek3 d1 #bb1 and ,greek3 e ,canis ,majoris to the stars in ,orion's belt 7,greek3 d1 e1 and ,greek3 z ,orionis72 and ,greek3 2 and ,greek3 k ,canis ,majoris with ,greek3 k and ,greek3 b ,orionis4#dcd ,the ,arabic name of ,sirius was al-schira1 which might easily be corrupted into ,sirius4 ,the ,hebrew name was ,sihor4 ,according to ,plutarch1 the ,ethiopians paid regal honours to the ,celestial ,dog4 ,the ,romans used to sacrifice a dog in its honour at the fetes called ,robigalia1 which were held on the seventh day before the ,calends of ,may1 and nine days after the entry of the sun into ,taurus4 ,pliny says1 ,hoc tempus ,varro determinat sole decimam partem ,tauri obtinenti quod canis occidit1 sidus per se vehemens1 etc4#dce ,owing to some remarks of ,cicero1 ,horace1 and ,seneca1 it has been supposed that in ancient times ,sirius was of red colour4 ,seneca says1 ,nec mirum est1 si terra omnis generis et varia evaporatio est2 quam in coelo quoque non unus appareat color rerum1 sed acrior sit ,canicul rubor1 ,nartis remissior1 ,jovis nullus1 in lucem puram nitore perducto4#dcf ,it is now brilliantly white with a bluish tinge4 ,but this change of colour is somewhat doubtful4 ,the remarks of the ancient writers may possibly refer to its great brilliancy rather than its colour4 ,al-,sufi says nothing about its colour1 and it was probably a white star in his time4 ,if it were red in his day he would most probably have mentioned the fact1 as he does in the case of several red stars4 ,brown1 however1 quotes the following from ,ibn ,alraqqa1 an ,arabian observer3-- ,i recognize ,sirius shining red1 whilst the morning is becoming white4 ,the night fading away1 has risen and left him1 ,the night is not afraid to lose him1 since he follows her4 ,schjellerup thinks that it is very doubtful that ,sirius was really red as seen by ,hipparchus and ,ptolemy4 ,but in an exhaustive inquiry made by ,dr4 ,see on the supposed change of colour1#dcg he comes to the conclusion that ,sirius was really red in ancient times4 ,seneca states distinctly that it was redder than ,mars 7see extract above71 and other ancient writers refer to its red colour4 ,it has been generally supposed that the ,arabian astronomer ,alfraganus1 in his translation of ,ptolemy's ,almagest1 refers to only five red stars observed by ,ptolemy1 namely1 ,arcturus1 ,aldebaran1 ,betelgeuse1 ,antares1 and ,pollux4 ,but ,dr4 ,see shows that this idea is due to a mistranslation of ,alfraganus by ,plato ,tibertinus in #aecg1 and that ,ptolemy did not speak of five red stars1 but five nebulous stars1 as stated by ,christmann and ,golius4 ,ptolemy described ,sirius as ,greek3 upokirros1 fiery red1 the same word used with reference to the other stars mentioned above4 ,the change of colour1 if any1 probably took place before ,al-,sufi's time4 ,dr4 ,see says-- ,prof4 ,newcomb rejects the former well-authenticated redness of ,sirius1 because he cannot explain the fact4 ,but the ink was scarcely dry on his new book on the stars1 in which he takes this position1 when ,nova ,persei blazed forth in #aija2 and observers saw it change colour from day to day and week to week4 ,could any one explain the cause of these numerous and conspicuous changes of colour8 ,shall we1 then1 deny the changes of colour in ,nova ,persei1 some of which were noticed when it was nearly as bright as ,sirius8#dch ,on the ceiling of the ,memnonium at ,thebes the heliacal rising of ,sirius is represented under the form and name of ,isis4 ,the coincidence of this rising with the annual rising of the ,nile is mentioned by ,tibullus and ,aclian4 ,about #djjj ,b4,c4 the heliacal rising of ,sirius coincided with the summer solstice 7about ,june #ba7 and the beginning of the rising of the ,nile4 ,the festival in honour of this event was held by the ,egyptians about ,july #bj1 and this marked the beginning of the sacred ,egyptian year4 ,on the summit of ,mount ,pelion in ,thessaly there was a temple dedicated to ,zeus1 where sacrifices were offered at the rising of ,sirius by men of rank who were chosen for the purpose by the priests and wore fresh sheepskins4 ,sirius seems to have been worshipped by the ancient ,egyptians under the name of ,sothis1 and it was regarded as the star of ,isis and ,osiris4 ,the last name without the initial ,o very much resembles our modern name4 ,according to ,al-,sufi1 the ,arabians called ,sirius al-schira al-abr1 ,sirius which has passed across1 also al-schira al ,jamnija1 the ,sirius of ,ymen4 ,he says it is called al-abr1 because it has passed across the ,milky ,way into the southern region4 ,he relates a mythological story why ,sirius fled towards the south and passed across the ,milky ,way towards ,suhail 7,canopus74 ,the same story is told by ,albufaragius#dci 7thirteenth century74 7,the story was probably derived from ,al-,sufi47 ,now1 it seems to me a curious and interesting fact that the large proper motion of ,sirius would have carried it across the ,milky ,way from the eastern to the western border in a period of #fj1jjj years4 ,possibly the ,arabian story may be based on a tradition of ,sirius having been seen on the opposite1 or eastern1 side of the ,milky ,way by the men of the early ,stone ,age4 ,however this may be1 we know from the amount and direction of the star's proper motion that it must have passed across the ,milky ,way from east to west within the period above stated4 ,the ,arabic name al-abr is not1 therefore1 a merely fanciful one1 but denotes an actual fact4 ,the proper motion of ,sirius could not possibly have been known to the ancients1 as it was only revealed by accurate modern observations4 ,the little constellation ,canis ,minor1 the ,little ,dog1 lies south of ,gemini and ,cancer4 ,small as it is1 it was one of the original forty-eight constellations of ,ptolemy4 ,in the ,greek mythology it was supposed to represent either one of ,diana's hunting dogs1 or one of ,orion's hounds4 ,ovid calls it the dog of ,icarus4 ,others say it was the dog of ,helen1 who was carried off by ,paris4 ,according to the old poets1 ,orion's dog1 or the dog of ,icarus1 threw himself into a well after seeing his master perish4 ,the name ,fovea1 given to the constellation by ,bayer1 signifies a pit where corn was deposited4 ,this comes from the fact that the rising of the star ,procyon 7,greek3 a ,canis ,minoris7 indicated the season of abundance4 ,but ,lalande thought it more probable that the idea of a pit came from the ,greek ,greek3 seiros1 which means a corn store1 and that it was confounded with ,sirius4 ,the name of the bright star ,procyon 7,greek3 a ,canis ,minoris7 is derived from the ,greek ,greek3 prokun1 the advanced day1 because it appeared in the morning sky before ,sirius4 ,procyon was called by the ,hindoos ,hanouman after their famous monkey god1 from whose tail a bridge is said to have been formed to enable the army of ,rama to pass from ,india to ,ceylon4 ,al-,sufi says that the star was marked on the old astrolabes as al-schira al-schamia1 the ,syrian ,sirius4 ,it was also called1 he says1 al-schira al-gumaisa1 the ,sirius with blear eyes 767 from weeping because ,sirius had passed across the ,milky ,way1 ,procyon remaining on the eastern side4 ,here we have the same legend again4 ,the proper motion of ,procyon 7about the same in amount and direction as that of ,sirius7 shows that the star has been on the eastern side of the ,milky ,way for many ages past4 ,about #fj1jjj years hence1 ,procyon will be near the star ,greek3 th ,canis ,majoris1 and will then--like ,sirius--have passed across the ,milky ,way4 ,argo1 the ,ship1 is a large constellation south of ,hydra1 ,monoceros1 and ,canis ,major4 ,it is called by ,al-,sufi al-safna1 the ,ship4 ,it is supposed to represent the first ship ever built4 ,the name is derived from the builder ,argo1 or from the ,greek word ,greek3 ,argos4 ,this ship is said to have been built in ,thessaly by order of ,minerva and ,neptune1 to go on the expedition for the conquest of the golden fleece4 ,the date of this expedition1 commanded by ,jason1 is usually fixed at #acjj or #adjj ,b4,c4 ,with reference to the position of this supposed ship in the sky1 ,proctor says1 ,it is noteworthy that when we make due correction for the effects of precession during the past #djjj years1 the old constellation ,argo is set on an even keel1 instead of being tilted some #de to the horizon1 as at present when due south4 ,he connects ,argo with ,noah's ,ark4 ,the brightest star of ,argo is ,canopus1 called ,suhal by ,al-,sufi4 ,it is the second brightest star in the heavens2 but it is not visible in northern latitudes4 ,the ,harvard photometric measures make it nearly one magnitude brighter than the zero magnitude1 about two magnitudes brighter than ,aldebaran1 and about half the brightness of ,sirius4 ,this fine star has been suspected of variable light4 ,webb says1 ,it was thought 7#ahfa7 in ,chili brighter than ,sirius4 ,observing it in the ,punjab1 the present writer found it on several occasions but little inferior to ,sirius1 although very low on the southern horizon4 ,from recent observations by ,mr4 ,h4 ,c4 ,mc,kay in ,australia1 he believes that it is variable to the extent of at least half a magnitude4#ddj ,but it is difficult to establish variations of light in very bright stars4 ,the parallax of ,canopus is very small1 so its distance from the earth is very great1 and it must be a sun of gigantic size4 ,according to ,al-,fargani1 ,canopus was called the star of ,st4 ,catherine by the ,christian pilgrims in the tenth century4#dda ,it was called ,suhal by the old ,arabians1 a name apparently derived from the root sahl1 a plain2 and ,schjellerup suggests that the name was probably applied to this and some other southern stars because they seem to move along a plain near the southern horizon4 ,al-,sufi says that he measured the latitude of ,schiraz in ,persia1 where he observed1 and found it to be #bi #cf'2 and hence for that place ,canopus1 when on the meridian1 had an altitude of about #i4 ,canopus was the ancient name of ,aboukir in ,egypt1 and is said to have derived its name from the pilot of ,menelaus1 whose name was ,kanobus1 and who died there from the bite of a snake4 ,the star is supposed to have been named after him1 and it was worshipped by the ancient ,egyptians4 ,al-,sufi does not mention the famous variable star ,greek3 ,args1 which1 owing to the precession of the equinoxes1 he might possibly have seen close to the horizon1 if it had been a bright star in his day4 ,it lies between ,greek3 ph ,velorum and ,greek3 a ,crucis4 ,both of these stars are mentioned by ,al-,sufi1 but he says nothing of any bright star 7or indeed any star7 between them4 ,this negative evidence tends to show that ,greek3 ,args was not visible to the naked eye in ,al-,sufi's time4 ,this extraordinary star has in modern times varied through all degrees of brightness from ,sirius down to the #hth magnitude6 ,schnfeld thought that a regular period is very improbable4 ,it seems to be a sort of connecting link between the long period variables and the nov or temporary stars4 ,it is reddish in colour1 and the spectrum of its light is very similar to that of the temporary stars4 ,whether it will ever become a brilliant object again1 time alone can tell2 but from the fact that it was presumably faint in ,al-,sufi's time1 and afterwards increased to the brightness of ,sirius1 it seems possible that its light may again revive4 ,the long constellation ,hydra lies south of ,cancer1 ,leo1 ,crater1 ,corvus1 ,virgo1 and ,libra4 ,it was also called ,asina1 ,coluber1 ,anguis1 ,sublimatus1 etc4 ,in the ,greek mythology it was supposed to represent the ,lernan serpent killed by ,hercules4 ,according to ,ovid1 who fixed its acronycal rising for ,february #ad1 it had a common origin with ,corvus and ,crater4 ,apollo1 wishing to sacrifice to ,jupiter1 sent the ,crow with a cup to fetch water4 ,on his way to the well the ,crow stopped at a fig tree and waited for the fruit to ripen6 ,afterwards1 to excuse his delay1 he said that a serpent had prevented him from drawing the water4 ,but ,apollo1 to punish the ,crow for his deception1 changed his plumage from white to black1 and ordered the serpent to prevent the ,crow from drinking4#ddb ,hydra was called by ,al-,sufi al-schudja1 the ,serpent1 or ,hydra4 ,he says that it contains twenty-five stars in the figure and two 'outside'1 and its head is to the south of the southern scale of the ,balance 7,greek3 a ,libr74 ,but this is clearly a mistake 7one of the very few errors to be found in ,al-,sufi's work71 for he goes on to say that the head is composed of four stars forming a figure like the head of a horse1 and he adds1 ,this head is in the middle between al-shira al-gumaisa ,procyon and ,kalb al-asad ,regulus the ,heart1 inclining from these two stars a little to the south4 ,this clearly indicates the stars ,greek3 d1 e1 1 and ,greek3 s ,hydr which1 with ,greek3 z ,hydr1 have always been considered as forming the ,hydra's head4 ,these stars lie south of ,greek3 a and ,greek3 b ,cancri1 not south of ,libra as ,al-,sufi says 7doubtless by a slip of the pen74 ,ptolemy's #abth star of ,hydra 7,greek3 a ,hydr7 is1 ,al-,sufi says1 the bright red star which is found at the end of the neck where the back begins2 it is of the #bnd magnitude4 ,it is that which is marked on the astrolabe as unk al-schudja1 'the neck of the serpent1' also al-fard1 'the solitary one4' ,al-,sufi's estimate of its brightness agrees well with modern measures2 but it has been suspected of variable light4 ,sir ,john ,herschel's estimates at the ,cape of ,good ,hope varied from #age to #beh magnitude4 ,he thought that its apparent variation might be due to its reddish colour1 and compares it to the case of ,greek3 a ,cassiopei4 ,but as this latter star is now known to be irregularly variable it seems probable that ,greek3 a ,hydr may be variable also4 ,gemmill found it remarkably bright on ,may #i1 #ahhc1 when he thought it nearly equal to ,pollux 7#ab magnitude74 ,on the other hand1 ,franks thought it nearer the #crd than the #bnd magnitude on ,march #b1 #ahgh4 ,on ,april #i1 #ahhd1 the present writer found it only slightly less than ,regulus 7#ac magnitude74 ,on ,april #f1 #ahhf1 how-ever1 it was considerably less than ,regulus1 but half a magnitude brighter than ,greek3 b ,canis ,minoris1 or about #b-a_/b magnitude4 ,in the ,chinese ,annals it is called the ,red ,bird4 ,in a list of thirty stars found on a tablet at ,birs-,nimroud1 it is called ,the son of the supreme temple4 ,although to the naked eye deserving the name of ,alphard or the solitary one1 it is by no means an isolated star when examined with a telescope4 ,it has a faint and distant companion1 observed by ,admiral ,smyth2 and about #be' to the west of it ,ward saw a small double star 7#h1 #ac3 #ij3 #ej74 ,with a #c-;inch refractor in the ,punjab1 ,i saw a small star of about #h-a_/b magnitude to the south and a little east of the bright star1 probably identical with ,smyth's companion4 ,farther off in the same direction ,i saw a fainter star1 and others at greater distances in the field4 ,there is also a faint star a little to the north4 ,i also saw ,ward's double with the #c-;inch telescope4 ,there is some difficulty in identifying the stars numbered by ,ptolemy #ac1 #ad1 and #ae in ,hydra4 ,having plotted a map from ,ptolemy's positions 7as given by ,al-,sufi71 ,i have come to the conclusion that ,ptolemy's stars are #ac ,greek3 k ,hydr2 #ad ,greek3 u2 and #ae ,greek3 l ,hydr1 probably4 ,from the clear description given by ,al-,sufi of the stars observed by him1 ,i find that his stars are #ac ,greek3 u#a2 #ad ,greek3 u#b2 and #ae ,greek3 l ,hydr4 ,we must1 therefore1 conclude that ,ptolemy and ,al-,sufi saw only three stars where now there are four1#ddc and that ,greek3 k ,hydr was not seen1 or at least is not mentioned by ,al-,sufi4 ,greek3 k is1 therefore1 probably variable4 ,it was rated #d by ,tycho ,brah1 ,bayer1 and ,hevelius2 it is at present about #eth magnitude4 ,if ,ptolemy did not see ,greek3 u#b it is probably variable also1 and1 indeed1 it has been suspected of variable light4#ddd ,the small constellation of ,crater1 the ,cup1 lies north of ,hydra1 and south of ,leo and ,virgo4 ,al-,sufi calls it al-batija1 the ,jar1 or ,cup4 ,he says the ,arabians called it al-malif1 the ,crib1 or ,manger4 ,according to ,brown1 the stars of ,crater exactly form a ,bakhian ,greek3 kantharos1 with its two handles rising above the two extremities of the circumference4#dde ,an ,asia ,minor legend connected ,crater with the mixing of human blood with wine in a bowl4 ,crater is referred to by ,ovid in the lines-- ,dixit et antiqui monumenta perennia facti ,anguis1 ,avis1 ,crater sidera1 juncta micunt4 ,the star ,greek3 a ,crateris was rated #dth magnitude by ,al-,sufi and all other observers1 and the ,harvard measures make it #dbj1 a satisfactory agreement4 ,it has three companions noted by ,admiral ,smyth4 ,one of these he called intense blood colour4 ,this is ,r ,crateris1 now known to be variable from above the #hth magnitude to below the #ith4 ,sir ,john ,herschel called it an intense scarlet star1 a curious colour4 ,with #c-;inch refractor in the ,punjab ,i found it full scarlet4 ,it is one of an open pair1 the further of the two from ,greek3 a4 ,there is a third star about #ith magnitude a little south of it4 ,ward saw a #acth magnitude star between ,greek3 a and ,r with a #b-g_/h-;inch 7,wray7 refractor4 ,this ,i saw readily with my #c-;inch4 ,smyth does not mention this faint star1 although he used a much larger telescope4 ,corvus1 the ,crow1 is a small constellation1 north of ,hydra4 ,aratus says the ,crow form seems to peck the fold of the water snake 7,hydra74 ,the victory which ,valerius ,corvinus is said to have owed to a crow has given it the name of ,pomptina1 because the victory took place near the ,pontine marshes4#ddf ,a quadrilateral figure is formed by its four brightest stars1 ,greek3 g1 d1 b1 and ,greek3 e ,corvi4 ,this figure has sometimes been mistaken for the ,southern ,cross by those who are not familiar with the heavens4 ,but the stars of the ,southern ,cross are much brighter4 ,the constellation ,centaurus1 the ,centaur1 lies south of ,hydra and ,libra1 and north of the ,southern ,cross4 ,according to ,dupuis1 ,centaurus represents the #crd labour of ,hercules1 his triumph over the ,centaurs4#ddg ,the ,centaurs were supposed to be a people living in the vicinity of ,mount ,ossa1 who first rode on horses4 ,the constellation was also called ,semivir1 ,chiron1 ,phobos1 ,minotaurus1 etc4 ,al-,sufi says it is represented by the figure of an animal1 of which the forepart is the upper part of a man from the head to end of the back1 and its hinder part is the hinder part of a horse1 from the beginning of the back to the tail4 ,it is to the south of the ,balance ,libra turning its face towards the east1 and the hinder part of the beast towards the west4 ,al-,sufi describes very clearly the four bright stars of the famous ,southern ,cross4 ,owing to precession these stars were some #g further north in the tenth century than they are at present1 and they could have been all seen by ,al-,sufi1 when on the meridian4 ,in the time of ,ptolemy and ,hipparchus1 they were still further north1 and about #ejjj years ago they were visible in the latitude of ,london4 ,dante speaks of these four stars as emblematical of the four cardinal virtues1 ,justice1 ,temperance1 ,fortitude1 and ,prudence4 ,closely south-east of ,greek3 a and ,greek3 b ,crucis is the dark spot in the ,milky ,way known as the ,coal ,sack1 which forms such a conspicuous object near the ,southern ,cross4 ,it was first described by ,pinzon in #adii2 and afterwards by ,lacaille in #agee4 ,although to the naked eye apparently black1 photographs show that it contains many faint stars1 but1 of course1 much less numerous than in the surrounding regions4 ,the dark effect is chiefly caused by contrast with the brilliancy of the ,milky ,way surrounding it4 ,al-,sufi also mentions the bright stars ,greek3 a and ,greek3 b ,centauri which follow the ,southern ,cross4 ,he says that the distance between them is four cubits1 that is about #i #bj'1 but it is less than this now4 ,greek3 a has a large proper motion of #cfg per annum1 and was farther from ,greek3 b in ,al-,sufi's time than it is at present4 ,this1 however1 would not wholly account for the difference1 and ,al-,sufi's over-estimate is probably due to the well-known effect by which the distance between two stars is apparently increased when they are near the horizon4 ,several of ,al-,sufi's distances between southern stars are over-estimated1 probably for the same reason4 ,the constellation ,lupus1 the ,wolf1 is south of ,libra and ,scorpio4 ,it lies along the western border of the ,milky ,way4 ,according to ancient writers it represents ,lycaon1 ,king of ,arcadia1 a contemporary of ,cecrops1 who is said to have sacrificed human victims1 and on account of his cruelty was changed into a wolf4 ,another fable is that it represents a wolf sacrificed by the ,centaur ,chiron4 ,according to ,brown1 ,lupus appears on the ,euphratian planisphere discovered by ,george ,smyth in the palace of ,sennacherib4 ,al-,sufi called it al-sabu1 the ,wild ,beast4 ,it was also called al-fand1 the ,leopard1 and al-asada1 the ,lioness4 ,ara1 the ,altar1 lies south of ,scorpio4 ,according to ancient writers it represents an altar built by ,vulcan1 when the gods made war against the ,titans4 ,it is called by ,al-,sufi al-midjman1 the ,scent ,box1 or the ,altar4 ,the little constellation ,corona ,australis1 the ,southern ,crown1 lies south and west of ,sagittarius1 east of ,scorpio1 and west of ,telescopium4 ,aratus refers to the stars in ,corona ,australis as-- ,other few ,before the ,archer under his forefeet ,led round in circle roll without a name4#ddi ,but the constellation was known by the names ,caduceus1 ,orbiculus1 ,corona ,sagittarii1 etc4 ,the ancient poets relate that ,bacchus placed this crown in the sky in honour of his mother ,semele4#dej ,others say that it represents the crown conferred on ,corinne of ,thebes1 famous as a poet4 ,the small constellation ,piscis ,australis1 or the ,southern ,fish1 lies south of ,capricornus and ,aquarius4 ,in the most ancient maps it is represented as a fish drinking the water which flows from the urn of ,aquarius4 99 99 99 99 99 ,a good many constellations have been added to the heavens since the days of ,al-,sufi1 and notes on some of these may be of interest4 ,,camelopardalis4--,this constellation first appears on a celestial planisphere published by ,bartschius in the year #afbd4 ,it was not formed by ,bartschius himself1 but by the navigators of the sixteenth century4 ,it lies south of ,ursa ,minor1 north of ,perseus and ,auriga1 east of ,draco1 and west of ,cassiopeia4 ,it contains no star brighter than the #dth magnitude4 ,,lynx4--,this constellation is south of ,camelopardalis and ,ursa ,major1 and north of ,gemini and ,cancer4 ,it was formed by ,hevelius in #affj1 and he called it the ,lynx1 because1 he said1 it contained only faint stars and it was necessary to have the eyes of a lynx to see them6 ,some of them were1 however1 observed by ,ptolemy and ,al-,sufi1 and are mentioned by the latter under ,ursa ,major4 ,,canes ,,venatici1 or the ,hunting ,dogs4--,this was formed by ,hevelius in #affj4 ,it lies south of the ,great ,bear's tail1 north of ,coma ,berenices1 east of ,ursa ,major1 and west of ,botis4 ,its brightest stars ,greek3 a 7#ab7 and ,greek3 b 7#h7 were observed by ,al-,sufi1 and included by him in the extern stars of ,ursa ,major4 ,,coma ,,berenices4--,this constellation lies between ,canes ,venatici and ,virgo4 ,although it was not included among the old forty-eight constellations of ,ptolemy1 it is referred to by ,al-,sufi as the ,plat1 or ,tress of ,hair1 and he included its stars ,flamsteed #ab1 #ae1 and #ba in the extern stars of ,leo4 ,it was originally formed by the poet ,callimachus in the third century ,b4,c41 but was not generally accepted until reformed by ,hevelius4 ,callimachus lived at ,alexandria in the reigns of ,ptolemy ,philadelphus and ,ptolemy ,euergetes1 and was chief librarian of the famous library of ,alexandria from about ,b4,c4 #bfj until his death in ,b4,c4 #bdj4 ,eratosthenes was one of his pupils4 ,the history of the constellation is as follows3 ,berenice1 wife of ,ptolemy ,euergetes1 made a vow1 when her husband was leaving her on a military expedition1 that if he returned in safety she would cut off her hair and consecrate it in the temple of ,mars4 ,her husband returned1 and she fulfilled her vow4 ,but on the next day the hair had disappeared--stolen from the temple--and ,conon the mathematician showed ,ptolemy seven stars near the constellation of the ,lion which did not belong to any constellation4 ,these were formed into a constellation and called ,berenice's ,hair4 ,conon is referred to by ,catullus in the lines-- ,idem me ille ,conon coeleste numine vidit ,e4 ,berenico vertice ,csariem4 ,coma ,berenices first occurs as a distinct constellation in the catalogue contained in the ,rudolphine ,tables formed by ,kepler 7epoch #afjj7 from the observations of ,tycho ,brah4#dea ,bayer substituted a sheaf of corn1 an idea derived from an ancient manuscript4 ,,leo ,,minor4--,this small constellation lies between ,ursa ,major and ,leo1 and east of the ,lynx4 ,it was formed by ,halley about the year #affj2 but is referred to by ,al-,sufi1 who includes one of its stars 7,fl4 #da7 in the extern stars of ,leo4 ,there are1 however1 several brighter stars in the group4 ,the brightest1 ,fl4 #df1 was measured #cib at ,harvard4 ,the star ,fl4 #cg was called prcipua 7or brightest7 by ,tycho ,brah1 and rated #c1 but as it was measured only #dgg at ,harvard it may possibly have diminished in brightness4 ,,sextans4--,this constellation lies south of ,leo1 and north and east of ,hydra4 ,it was formed by ,hevelius about the year #afhj4 ,according to the ,harvard photometric measures its brightest star is ,fl4 #ae 7#dej74 ,,monoceros1 or the ,unicorn1 lies south of ,gemini and ,canis ,minor1 north of ,canis ,major and ,argo1 east of ,orion1 and west of ,hydra4 ,it appears on the planisphere of ,bartschius1 published in #afbd4 ,according to ,scaliger it is shown on an old ,persian sphere4 ,one of its stars1 ,fl4 #bb1 is mentioned by ,al-,sufi among the extern stars of ,canis ,major 7,no4 #a74 ,another1 ,fl4 #cj1 is given under ,hydra 7,extern ,no4 #a7 and ,fl4 #h1 #ac1 and #ae are apparently referred to in ,gemini4 ,the star #ae ,monocerotis is a little south of ,greek3 x ,geminorum1 and was measured #dei magnitude at ,harvard4 ,it was at one time supposed to be variable with a short period 7about #c-a_/b days71 but this variation has not been confirmed4 ,the spectrum is of the fifth type--with bright lines--a very rare type among naked-eye stars4 ,it is a triple star 7#e1 #hh1 #aab3 #bi1 #afc7 and should be seen with a #d-;inch telescope4 ,it has several other small companions1 one of which 7#acib3 #geg7 has been suspected of variation in light4 ,it was estimated #h-a_/b by ,main in #ahfc1 but only #ab by ,sadler in #ahge4 ,observing it on ,march #bh1 #ahhi1 with #c-;inch refractor1 ,i found it about one magnitude brighter than a star closely preceding1 and estimated it #h or #h-a_/b magnitude4 ,it is probably variable and should be watched4 ,,scutum ,,sobieski4--,this is1 or was1 a small constellation in the southern portion of ,aquila1 which was formed by ,hevelius in #affj in honour of the ,polish hero ,sobieski4 ,its principal stars1 which lie south-west of ,greek3 l ,aquil1 were mentioned by ,al-,sufi and are referred to by him under that constellation4 ,it contains a very bright spot of ,milky ,way light1 which may be well seen in the month of ,july just below the star ,greek3 l ,aquil4 ,closely south of the star #f ,aquil is a remarkable variable star ,r ,scuti 7,r4,a4 #ah;h #dbm#b1 ,s4 #e #di'74 ,it varies from #dh to #gh with an irregular period4 ,all the light changes can be observed with a good opera-glass4 ,,vulpecula1 the ,fox4--,this modern constellation lies south of ,cygnus1 north of ,sagitta and ,delphinus1 east of ,hercules1 and west of ,pegasus4 ,it was formed by ,hevelius in #affj4 ,one of its stars1 #f ,vulpecul1 is mentioned by ,al-,sufi in describing the constellation ,cygnus4 ,closely north-west of #cb ,vulpecul is the short-period variable ,t ,vulpecul4 ,it varies from #ee to #fb magnitude1 and its period is #ddcf days4 ,this is an interesting object1 and all the changes of light can be observed with an opera-glass4 ,,lacerta4--,this little constellation lies south of ,cepheus and north of ,pegasus4 ,its formation was first suggested by ,roger and ,anthelm in #afgi1 and it was called by them ,the ,sceptre and the ,hand of ,justice4 ,it was named ,lacerta by ,hevelius in #afij1 and this name it still retains4 ,al-,sufi seems to refer to its stars in his description of ,andromeda1 but does not mention any star in particular4 ,it brightest star ,fl4 #g 7,greek3 a ,lacert7 is about the #dth magnitude4 ,about one degree south-west of #g is #e ,lacert1 a deep orange star with a blue companion in a fine field4 ,there are some constellations south of the ,equator which1 although above ,al-,sufi's horizon when on the meridian1 are not described by him1 as they were formed since his time4 ,these are as follows3-- ,,sculptor4--,this constellation lies south of ,aquarius and ,cetus1 and north of ,phoenix4 ,some of its stars are referred to by ,al-,sufi under ,eridanus as lying within the large triangle formed by ,greek3 b ,ceti1 ,fomalhaut1 and ,greek3 a ,phoenicis4 ,the brightest star is ,greek3 a1 about #ab south of ,greek3 b ,ceti 7#dci magnitude ,harvard74 ,about #g south-east of ,greek3 a is the red and variable star ,r ,sculptoris2 variable from #fb to #hh magnitude1 with a period of about #cgf days4 ,gould describes it as intense scarlet4 ,it has a spectrum of the fourth type4 ,,phoenix4--,this constellation lies south of ,sculptor4 ,some of its stars are referred to by ,al-,sufi1 under ,eridanus1 as forming a boat-shaped figure4 ,these are evidently ,greek3 a1 k1 m1 b1 n1 and ,greek3 g4 ,greek3 a is at the south-eastern angle of ,al-,sufi's triangle referred to above 7under ,sculptor74 7,see ,proctor's ,atlas1 ,no4 #c47 ,,fornax1 the ,furnace1 lies south of ,cetus1 west of ,eridanus1 and east of ,sculptor and ,phoenix4 ,it was formed by ,lacaille1 and is supposed to represent a chemical furnace with an alembic and receiver6 ,its brightest star1 ,greek3 a ,fornacis1 is identical with #ab ,eridani4 ,c,,lum1 the ,sculptor's ,tools1 is a small constellation east of ,columba1 and west of ,eridanus4 ,it was formed by ,lacaille4 ,the brightest stars are ,greek3 a and ,greek3 g1 which are about #d-a_/b magnitude4 ,greek3 a has a faint companion2 and ,greek3 g is a wide double star to the naked eye4 ,,antlia1 the ,air ,pump1 lies south of ,hydra1 east and north of ,argo1 and west of ,centaurus4 ,it was formed by ,lacaille4 ,it contains no star brighter than #dth magnitude4 ,the brightest1 ,greek3 a1 has been variously rated from #d to #e1 and ,stanley ,williams thinks its variability highly probable4 ,,norma1 the ,rule1 lies south of ,scorpio4 ,it contains no star brighter than the #dth magnitude4 ,,telescopium4--,this modern constellation lies south of ,corona ,australis1 and north of ,pavo4 ,its stars ,greek3 a1 d1 and ,greek3 z1 which lie near the northern boundary of the constellation1 are referred to by ,al-,sufi in his description of ,ara4 ,,microscopium4--,this small constellation is south of ,capricornus1 and west of ,piscis ,australis4 ,its stars seem to be referred to by ,al-,sufi as having been seen by ,ptolemy1 but he does not specify their exact positions4 ,it contains no star brighter than #d-a_/b magnitude4 99 99 99 99 99 ,south of ,al-,sufi's horizon are a number of constellations surrounding the south pole1 which1 of course1 he could not see4 ,most of these have been formed since his time1 and these will now be considered2 beginning with that immediately surrounding the ,south ,pole 7,octans71 and then following the others as nearly as possible in order of ,right ,ascension4 ,,octans4--,this is the constellation surrounding the ,south ,pole of the heavens4 ,there is no bright star near the ,pole1 the nearest visible to the naked eye being ,greek3 s ,octantis1 which is within one degree of the pole4 ,it was estimated #eh at ,cordoba4 ,the brightest star in the constellation is ,greek3 n ,octantis 7,greek3 a1 ,proctor71 which lies about #ab degrees from the pole in the direction of ,indus and ,microscopium4 ,the ,harvard measure is #cgd magnitude4 ,,hydrus1 the ,water-,snake1 is north of ,octans in the direction of ,achernar 7,greek3 a ,eridani74 ,the brightest star is ,greek3 b1 which lies close to ,greek3 th ,octantis4 ,the ,harvard measure is #bij4 ,gould says its colour is clear yellow4 ,it has a large proper motion of #bbh per annum4 ,sir ,david ,gill found a parallax of #jacd1 and this combined with the proper motion gives a velocity of #ej miles a second at right angles to the line of sight4 ,greek3 g ,hydri is a comparatively bright star of about the #crd magnitude1 about #ae-a_/b degrees from the ,south ,pole4 ,it is reddish1 with a spectrum of the third type4 ,,horologium1 the ,clock1 is north of ,hydra1 and south of ,eridanus4 ,three of its stars1 ,greek3 a1 d1 and ,greek3 ps1 at the extreme northern end of the constellation1 seem to be referred to by ,al-,sufi in his description of ,eridanus1 but he does not give their exact positions4 ,most of the stars forming this constellation were below ,al-,sufi's horizon4 ,,reticulum1 the ,net1 is a small constellation to the east of ,hydrus and ,horologium4 ,the brightest star of the constellation is ,greek3 a 7#ccf ,harvard1 #cc ,cordoba1 and coloured74 ,,dorado1 the ,sword ,fish1 lies east of ,reticulum and west of ,pictor4 ,it contains only two stars brighter than the #dth magnitude4 ,these are ,greek3 a 7#cdg ,harvard7 and ,greek3 b 7#cha ,harvard1 but suspected of variation74 ,about #c east of ,greek3 a ,reticuli is the variable star ,r ,doradus4 ,it varies from #dh to #fh1 and its period is about #cde days4 ,gould calls it excessively red4 ,it may be followed through all its fluctuations of light with an opera-glass4 ,,mensa1 or ,mons ,mensa1 the ,table ,mountain1 lies between ,dorado and the ,south ,pole1 and represents the ,table ,mountain of the ,cape of ,good ,hope4 ,it contains no star brighter than the #eth magnitude4 ,,pictor1 the ,painter's ,easel1 lies north of ,doradus1 and south of ,columba4 ,it contains no very bright stars1 the brightest being ,greek3 a 7#ccj ,harvard74 ,,volans1 the ,flying ,fish1 is north of ,mensa1 and south and west of ,argo4 ,its brighter stars1 with the exception of ,greek3 a and ,greek3 b1 form an irregular six-sided figure4 ,its brightest star is ,greek3 b 7#cfe7 according to the ,harvard measures4 ,the ,cordoba estimates1 however1 range from #cf to #dd1 and ,gould says its colour is bright yellow4 ,williams rated it #ch4 ,,cham,,lion4--,this small constellation lies south of ,volans1 and north of ,mensa and ,octans4 ,none of its stars are brighter than the #dth magnitude1 its brightest being ,greek3 a 7#djh ,harvard7 and ,greek3 g 7#daj74 ,,argo4--,this large constellation extends much further south than ,al-,sufi could follow it4 ,the most southern star he mentions is ,greek3 e ,carin1 but south of this are several bright stars4 ,greek3 b ,carin is #ahj according to the ,harvard measures2 ,greek3 u ,carin1 #cjh2 ,greek3 th1 #cjc2 ,greek3 1 #cef2 and others4 ,a little north-west of ,greek3 i is the long-period variable ,r ,carin 7#i;h #bim#g1 ,s4 #fb #ba'1 #aijj74 ,it varies from #de at maximum to #aj at minimum1 and the period is about #cjig days4 ,a little east of ,r ,carin is another remarkable variable star1 l ,carin 7,r4,a4 #i;h #dbm#e1 ,s4 #fb #c'74 ,it varies from #cf to #ej magnitude1 with a period of #ce-a_/b days from maximum to maximum4 ,all the light changes can be observed with an opera-glass1 or even with the naked eye4 ,it was discovered at ,cordoba4 ,the spectrum is of the solar type 7,g74 ,,musca1 the ,bee1 is a small constellation south of the ,southern ,cross and ,centaurus4 ,its brightest stars are ,greek3 a 7#bhd ,harvard7 and ,greek3 b 7#cbf74 ,these two stars form a fine pair south of ,greek3 a ,crucis4 ,closely south-east of ,greek3 a is the short-period variable ,r ,musc4 ,it varies from #fe to #gf magnitude1 and its period is about #ai hours4 ,all its changes of light may be observed with a good opera-glass4 ,,apus1 the ,bird of ,paradise1 lies south-east of ,musca1 and north of ,octans4 ,its brightest star is ,greek3 a1 about the #dth magnitude4 ,williams calls it deep yellow4 ,about #c north-west of ,greek3 a1 in the direction of the ,southern ,cross1 is ,greek3 th ,apodis1 which was found to be variable at ,cordoba from #e-a_/b to #f-a_/b4 ,the spectrum is of the third type1 which includes so many variable stars4 ,,triangulum ,,australis1 the ,southern ,triangle1 is a small constellation north of ,apus1 and south of ,norma4 ,a fine triangle1 nearly isosceles1 is formed by its three bright stars1 ,greek3 a1 b1 g1 the brightest ,greek3 a being at the vertex4 ,these three stars form with ,greek3 a ,centauri an elongated cross4 ,the stars ,greek3 b and ,greek3 g are about #crd magnitude4 ,greek3 b is reddish4 ,greek3 e 7#daa1 ,harvard7 is also reddish1 and is nearly midway between ,greek3 b and ,greek3 g1 and near the centre of the cross above referred to4 ,greek3 a is a fine star 7#ahh ,harvard7 and is one of the brightest stars in the sky--,no4 #cc in a list of #aejj highest stars given by ,pickering4 ,about #a #dj' west of ,greek3 e is the short-period variable ,r ,trianguli ,australis 7,r4,a4 #ae;h #ajm#h1 ,s4 #ff #h'7 discovered at ,cordoba in #ahga4 ,it varies from #fg to #gd1 and the period is about #c;d #g;h#b4 ,although not visible to ordinary eyesight it is given here1 as it is an interesting object and all its light changes may be well seen with an opera-glass4 ,a little south-east of ,greek3 b is another short-period variable1 ,s ,trianguli ,australis 7,r4,a4 #ae;h #ebm#b1 ,s4 #fc #cj'71 which varies from #fd to #gd1 with a period of #fc days2 and all its fluctuations of light may also be observed with a good opera-glass4 ,,circinus1 the ,compass1 is a very small constellation lying between ,triangulum and ,centaurus4 ,its brightest star1 ,greek3 a1 is about #c-a_/b magnitude1 about #d south of ,greek3 a ,centauri4 ,,pavo1 the ,peacock1 lies north of ,octans and ,apus1 and south of ,telescopium4 ,its brightest star is ,greek3 a1 which is a fine bright star 7#bab ,harvard74 ,greek3 k is a short-period variable4 ,it varies from #ch to #eb1 and the period is about #i days4 ,this is an interesting object1 as all the fluctations of light can be observed by the naked eye or an opera-glass4 ,greek3 e ,pavonis was measured #daj at ,harvard1 but the ,cordoba estimates vary from #cf to #db4 ,gould says it is of a remarkably blue colour4 ,,indus4--,this constellation lies north of ,octans1 and south of ,sagittarius1 ,microscopium1 and ,grus4 ,one of its stars1 ,greek3 a1 is probably referred to by ,al-,sufi in his description of ,sagittarius2 it lies nearly midway between ,greek3 b ,sagittarii and ,greek3 a ,gruis1 and is the brightest star of the constellation4 ,the star ,greek3 e ,indi 7#dgd ,harvard7 has a remarkably large proper motion of #dfh per annum4 ,its parallax is about #jbh1 and the proper motion indicates a velocity of about #di miles a second at right angles to the line of sight4 ,,toucan4--,this constellation lies north of ,octans1 and south of ,phoenix and ,grus1 east of ,indus1 and west of ,hydrus4 ,its brightest star is ,greek3 a1 of about the #crd magnitude4 99 99 99 99 99 ,there are seven celestial rivers alluded to by the ancient astronomers3-- #a4 ,the ,fish ,river1 which flows from the urn of ,aquarius4 #b4 ,the ,river of the ,bird1 or the ,milky ,way in ,cygnus4 #c4 ,the ,river of the ,birds--#b1 including ,aquila4 #d4 ,the ,river of ,orion--,eridanus4 #e4 ,the ,river of the god ,marduk--perhaps the ,milky ,way in ,perseus4 #f4 ,the ,river of ,serpents 7,serpens1 or ,hydra74 #g4 ,the ,river of ,gan-gal 7,the ,high ,cloud7--probably the ,milky ,way as a whole4 ,there are four serpents represented among the constellations4 ,these are ,hydra1 ,hydrus1 ,serpens1 and ,draco4 ,according to the late ,mr4 ,proctor the date of the building of the ,great ,pyramid was about #cdjj ,b4,c4#deb ,at this time the ,spring ,equinox was in ,taurus1 and this is referred to by ,virgil4 ,but this was not so in ,virgil's time1 when--on account of the precession of the equinoxes--the equinoctial point had already entered ,pisces1 in which constellation it still remains4 ,at the date #cdjj ,b4,c4 the celestial equator ran along the whole length of the constellation ,hydra1 nearly through ,procyon1 and a little north of the bright red star ,antares4 ,the star ,fomalhaut 7,greek3 a ,piscis ,australis7 is interesting as being the most southern #ast magnitude star visible in ,england1 its meridian altitude at ,greenwich being little more than eight degrees4#dec ,with reference to the ,greek letters given to the brighter stars by ,bayer 7in his ,atlas published in #afjc71 and now generally used by astronomers1 ,mr4 ,lynn has shown that although ,bayer did uniformly designate the brightest stars in each constellation by the letter ,greek3 a1#ded it is a mistake to suppose--as has often been stated in popular books on astronomy--that he added the other ,greek letters in order of brightness4 ,that this is an error clearly appears from ,bayer's own ,explicatio to his ,atlas1 and was long since pointed out by ,argelander 7#ahcb71 and by ,dr4 ,gould in his ,uranometria ,argentina4 ,gould says1 ,for the stars of each order1 the sequence of the letters in no manner represents that of their brightness1 but depended upon the positions of the stars in the figure1 beginning usually at the head1 and following its course until all the stars of that order of magnitude were exhausted4 ,mr4 ,lynn says1 ,perhaps one of the most remarkable instances in which the lettering is seen at a glance not to follow the order of the letters is that of the three brightest stars in ,aquila ,al-,sufi's 'three famous stars'1 ,greek3 g being evidently brighter than ,greek3 b4 ,but there is no occasion to conjecture from this that any change of relative brightness has taken place4 ,bayer reckoned both of these two of the third magnitude1 and appears to have arranged ,greek3 b before ,greek3 g1 according to his usual custom1 simply because ,greek3 b is in the neck of the supposed eagle1 and ,greek3 g at the root of one of the wings4#dee ,another good example is found in the stars of the ,plough1 in which the stars are evidently arranged in the order of the figure and not in the order of relative brightness4 ,in fact1 ,bayer is no guide at all with reference to star magnitudes4 ,how different ,al-,sufi was in this respect6 ,the stars ,aldebaran1 ,regulus1 ,antares1 and ,fomalhaut were called royal stars by the ancients4 ,the reason of this was that they lie roughly about #ij apart1 that is #f hours of ,right ,ascension4 ,so1 if through the north and south poles of the heavens and each of these stars we draw great circles of the sphere1 these circles will divide the sphere into four nearly equal parts1 and the ancients supposed that each of these stars ruled over a quarter of the sphere1 an idea probably connected with astrology4 ,as the position of ,aldebaran is ,r4,a4 #d;h #cjm1 ,declination ,north #af #ai'1 and that of ,antares is ,r4,a4 #af;h #aem1 ,declination ,south #be #b'1 these two stars lie at nearly opposite points of the celestial sphere4 ,from this it follows that our sun seen from ,aldebaran would lie not very far from ,antares1 and seen from ,antares it would appear not far from ,aldebaran4 ,the following may be considered as representative stars of different magnitudes4 ,for those of first magnitude and fainter ,i have only given those for which all the best observers in ancient and modern times agree1 and which have been confirmed by modern photometric measures4 ,the ,harvard measures are given3-- ,brighter than zero magnitude ,sirius 7-#aeh72 ,canopus 7-#jhf7 ,zero magnitude ,greek3 a ,centauri 7#jjf7 #j to #jd magnitude ,vega 7#jad72 ,capella 7#jba72 ,arcturus 7#jbd72 ,rigel 7#jcd7 #je magnitude ,procyon 7#jdh7 #ast ,aldebaran 7#ajf7 #bnd ,greek3 a ,persei 7#aij72 ,greek3 b ,aurig 7#bjg7 #crd ,greek3 ,botis 7#cjh72 ,greek3 z ,capricorni 7#bih7 #dth ,greek3 r ,leonis 7#che72 ,greek3 l ,scorpii 7#daf72 ,greek3 g ,crateris7#dad72 ,greek3 r ,herculis 7#dad7 #eth ,greek3 o ,pegasi 7#dhe72 ,greek3 m ,capricorni 7#eaj7 ,,chapter ,,xx ,the ,visible ,universe ,some researches on the distribution of stars in the sky have recently been made at the ,harvard ,observatory 7,u4,s4,a474 ,the principal results are3--7#a7 ,the number of stars on any given area of the ,milky ,way is about twice as great as in an equal area of any other region4 7#b7 ,this ratio does not increase for faint stars down to the #abth magnitude4 7#c7 ,the ,milky ,way covers about one-third of the sky and contains about half of the stars4 7#d7 ,there are about #aj1jjj stars of magnitude #ff or brighter1 #ajj1jjj down to magnitude #hg1 one million to magnitude #aa1 and two millions to magnitude #aai4 ,it is estimated that there are about #ah millions of stars down to the #aeth magnitude visible in a telescope of #ae inches aperture4#def ,according to ,prof4 ,kapteyn's researches on stellar distribution1 he finds that going out from the earth into space1 the star density--that is1 the number of stars per unit volume of space--is fairly constant until we reach a distance of about #bjj light years4 ,from this point the density gradually diminishes out to a distance of #bejj light years1 at which distance it is reduced to about one-fifth of the density in the sun's vicinity4#deg ,in a letter to the late ,mr4 ,proctor 7,knowledge1 ,november1 #ahhe1 p4 #ba71 ,sir ,john ,herschel suggested that our ,galaxy 7or stellar system7 contained within itself miniatures of itself4 ,this beautiful idea is probably true4 ,in his account of the greater ,magellanic cloud1 ,sir ,john ,herschel describes one of the numerous objects it contains as follows3-- ,very bright1 very large2 oval2 very gradually pretty1 much brighter in the middle2 a beautiful nebula2 it has very much the resemblance to the ,nubecula ,major itself as seen with the naked eye1 but it is far brighter and more impressive in its general aspect as if it were doubled in intensity4 ,note--,july #bi1 #ahcg4 ,i well remember this observation1 it was the result of repeated comparisons between the object seen in the telescope and the actual nubecula as seen high in the sky on the meridian1 and no vague estimate carelessly set down4 ,and who can say whether in this object1 magnified and analysed by telescopes infinitely superior to what we now possess1 there may not exist all the complexity of detail that the nubecula itself presents to our examination8#deh ,the late ,lord ,kelvin1 in a remarkable address delivered before the ,physical ,science ,section of the ,british ,association at its meeting at ,glasgow in #aija1 considered the probable quantity of matter contained in our ,visible ,universe4 ,he takes a sphere of radius represented by the distance of a star having a parallax of one-thousandth of a second 7or about #cjjj years' journey for light71 and he supposes that uniformly distributed within this sphere there exists a mass of matter equal to #ajjj million times the sun's mass4 ,with these data he finds that a body placed originally at the surface of the sphere would in #e million years acquire by gravitational force a velocity of about #ab-a_/b miles a second1 and after #be million of years a velocity of about #fg miles a second4 ,as these velocities are of the same order as the observed velocities among the stars1 ,lord ,kelvin concludes that there is probably as much matter in our universe as would be represented by a thousand million suns4 ,if we assumed a mass of ten thousand suns the velocities would be much too high4 ,the most probable estimate of the total number of the visible stars is about #ajj millions2 so that if ,lord ,kelvin's calculations are correct we seem bound to assume that space contains a number of dark bodies4 ,the nebul1 however1 probably contain vast masses of matter1 and this may perhaps account--partially1 at least--for the large amount of matter estimated by ,lord ,kelvin4 7,see ,chapter on ,nebul47 ,in some notes on photographs of the ,milky ,way1 ,prof4 ,barnard says with reference to the great nebula near ,greek3 r ,ophiuchi1 ,the peculiarity of this region has suggested to me the idea that the apparently small stars forming the ground work of the ,milky ,way here1 are really very small bodies compared with our own sun2 and again1 referring to the region near ,greek3 b ,cygni1 ,one is specially struck with the apparent extreme smallness of the general mass of the stars in this region4 ,again1 with reference to ,greek3 ch ,cygni1 he says1 ,the stars here also are remarkably uniform in size4#dei ,eastman's results for parallax seem to show that the fainter rather than the brighter stars are nearest to our system4 ,but this apparent paradox is considered by ,mr4 ,monck to be very misleading2#dfj and the present writer holds the same opinion4 ,prof4 ,kapteyn finds that stars whose proper motions exceed #jje are not more numerous in the ,milky ,way than in other parts of the sky2 or1 in other words1 if only the stars having proper motions of #jje or upwards were mapped1 there would be no aggregation of stars showing the existence of the ,milky ,way4#dfa ,with reference to the number of stars visible on photographs1 the late ,dr4 ,isaac ,roberts says-- ,so far as ,i am able at present to judge1 under the atmospheric conditions prevalent in this country1 the limit of the photographic method of delineation will be reached at stellar1 or nebular1 light of the feebleness of about #ahth-magnitude stars4 ,the reason for this inference is that the general illumination of the atmosphere by starlight concentrated upon a film by the instrument will mask the light of objects that are fainter than about #ahth-magnitude stars4#dfb ,with reference to blank spaces in the sky1 the late ,mr4 ,norman ,pogson remarked-- ,near ,s ,ophiuchi we find one of the most remarkable vacuities in this hemisphere--an elliptic space of about #fe' in length in the direction of ,r4,a41 and #dj' in width1 in which there exists no star larger than the #acth magnitude 444 it is impossible to turn a large telescope in that direction and1 if ,i may so express it1 view such black darkness1 without a feeling that we are here searching into the remote regions of space1 far beyond the limits of our own sidereal system4#dfc ,prof4 ,barnard describes some regions in the constellation ,taurus containing dark lanes in a groundwork of faint nebulosity4 ,he gives two beautiful photographs of the regions referred to1 and says that the dark holes and lanes are apparently darker than the sky in the immediate vicinity4 ,he says1 ,a very singular feature in this connection is that the stars also are absent in general from the lanes4 ,a close examination of these photographs has given the present writer the impression that the dark lanes and spots are in the nebulosity1 and that the nebulosity is mixed up with the stars4 ,this would account for the fact that the stars are in general absent from the dark lanes4 ,for if there is an intimate relation between the stars and the nebulosity1 it would follow that where there is no nebulosity in this particular region there would be no stars4 ,prof4 ,barnard adds that the nebulosity is easily visible in a #ab-;inch telescope4#dfd ,with reference to the life of the universe1 ,prof4 ,f4 ,r4 ,moulton well says-- ,the lifetime of a man seems fairly long1 and the epoch when ,troy was besieged1 or when the ,pharaohs piled up the pyramids in the valley of the ,nile1 or when our ancestors separated on the high plateaux of ,asia1 seems extremely remote1 but these intervals are only moments compared to the immense periods required for geological evolutions and the enormously greater ones consumed in the developement of worlds from widely extended nebulous masses4 ,we recognize the existence of only those forces whose immediate consequences are appreciable1 and it may be that those whose effects are yet unseen are really of the highest importance4 ,a little creature whose life extended over only two or three hours of a summer's day might be led1 if he were sufficiently endowed with intelligence1 to infer that passing clouds were the chief influence at work in changing the climate instead of perceiving that the sun's slow motion across the sky would bring on the night and its southward motion the winter4#dfe ,in a review of my book ,astronomical ,essays in ,the ,observatory1 ,september1 #aijg1 the following words occur4 ,they seem to form a good and sufficient answer to people who ask1 ,what is there beyond our visible universe8 ,if the stellar universe is contained in a sphere of say #ajjj stellar units radius1 what is there beyond8 ,to this the astronomer will reply that theories and hypotheses are put forward for the purpose of explaining observed facts2 when there are no facts to be explained1 no theory is required4 ,as there are no observed facts as to what exists beyond the farthest stars1 the mind of the astronomer is a complete blank on the subject4 ,popular imagination can fill up the blank as it pleases4 ,with these remarks ,i fully concur4 ,in his address to the ,british ,association1 ,prof4 ,g4 ,h4 ,darwin 7now ,sir ,george ,darwin7 said-- ,man is but a microscopic being relatively to astronomical space1 and he lives on a puny planet circling round a star of inferior rank4 ,does it not1 then1 seem futile to imagine that he can discover the origin and tendency of the ,universe as to expect a housefly to instruct us as to the theory of the motions of the planets8 ,and yet1 so long as he shall last1 he will pursue his search1 and will no doubt discover many wonderful things which are still hidden4 ,we may indeed be amazed at all that man has been able to find out1 but the immeasurable magnitude of the undiscovered will throughout all time remain to humble his pride4 ,our children's children will still be gazing and marvelling at the starry heavens1 but the riddle will never be read4 ,the ancient philosopher ,lucretius said-- ,globed from the atoms falling slow or swift ,i see the suns1 ,i see the systems lift ,their forms2 and even the system and the suns ,shall go back slowly to the eternal drift4#dff ,but it has been well said that the structure of the universe has a fascination of its own for most readers quite apart from any real progress which may be made towards its solution4#dfg ,the ,milky ,way itself1 ,mr4 ,stratonoff considers to be an agglomeration of immense condensations1 or stellar clouds1 which are scattered round the region of the galactic equator4 ,these clouds1 or masses of stars1 sometimes leave spaces between them1 and sometimes they overlap1 and in this way he accounts for the great rifts1 like the ,coal ,sack1 which allow us to see through this great circle of light4 ,he finds other condensations of stars2 the nearest is one of which our sun is a member1 chiefly composed of stars of the higher magnitudes which thin out rapidly as the ,milky ,way is approached4 ,there are other condensations3 one in stars of magnitudes #fe to #he2 and a third1 farther off1 in stars of magnitudes #gf to #h4 ,these may be called opera-glass1 or field-glass stars4 ,stratonoff finds that stars with spectra of the first type 7class ,a1 ,b1 ,c1 and ,d of ,harvard7 which include the ,sirian and ,orion stars1 are principally situated near the ,milky ,way1 while those of type ,,ii4 7which includes the solar stars7 are principally condensed in a region coinciding roughly with the terrestrial pole1 and only show a slight increase1 as compared with other stars1 as the galaxy is approached4#dfh ,prof4 ,kapteyn thinks that undoubtedly one of the greatest difficulties1 if not the greatest of all1 in the way of obtaining an understanding of the real distribution of the stars in space1 lies in our uncertainty about the amount of loss suffered by the light of the stars on its way to the observer4#dfi ,he says1 ,there can be little doubt in my opinion1 about the existence of absorption in space1 and ,i think that even a good guess as to the order of its amount can be made4 ,for1 first we know that space contains an enormous mass of meteoric matter4 ,this matter must necessarily intercept some part of the star-light4 ,this absorption1 however1 seems to be comparatively small4 ,kapteyn finds a value of #jjaf 7about #a_/fjth7 of a magnitude for a star at a distance corresponding to a parallax of one-tenth of a second 7about #cc light years74 ,this is a quantity almost imperceptible in the most delicate photometer4 ,but for very great distances--such as #cjjj light years--the absorption would evidently become very considerable1 and would account satisfactorily for the gradual thinning out of the fainter stars4 ,if this were fully proved1 we should have to consider the fainter stars of the ,milky ,way to be in all probability fairly large suns1 the light of which is reduced by absorption4 ,that some of the ancients knew that the ,milky ,way is composed of stars is shown by the following lines translated from ,ovid3-- ,a way there is in heaven's extended plain ,which when the skies are clear is seen below ,and mortals1 by the name of ,milky1 know2 ,the groundwork is of stars1 through which the road ,lies open to great ,jupiter's abode4#dgj ,from an examination of the distribution of the faint stars composing the ,milky ,way1 and those shown in ,argelander's charts of stars down to the #i-a_/b magnitude1 ,easton finds that there is a real connection between the distribution of #ith and #ajth magnitude stars1 and that of the faint stars of the ,milky ,way1 and that consequently the faint or very faint stars of the galactic zone are at a distance which does not greatly exceed that of the #ith and #ajth magnitude stars4#dga ,a similar conclusion was1 ,i think1 arrived at by ,proctor many years ago4 ,now let us consider the meaning of this result4 ,taking stars of the #aeth magnitude1 if their faintness were merely due to greater distance1 their actual brightness--if of the same size--would imply that they are at #aj times the distance of stars of the #ajth magnitude4 ,but if at the same distance from us1 a #ajth magnitude star would be #ajj times brighter than a #aeth magnitude star1 and if of the same density and intrinsic brightness 7or luminosity of surface7 the #ajth magnitude would have #aj times the diameter of the fainter star1 and hence its volume would be #ajjj times greater 7#ajc71 and this great difference is not perhaps improbable4 ,the constitution of the ,milky ,way is not the same in all its parts4 ,the bright spot between ,greek3 b and ,greek3 g ,cygni is due to relatively bright stars4 ,others equally dense but fainter regions in ,auriga and ,monoceros are only evident in stars of the #hth and #ith magnitude1 and the light of the well-known luminous spot in ,sobieski's ,shield1 closely south of ,greek3 l ,aquil1 is due to stars below magnitude #i-a_/b4 ,the correspondence in distribution between the stars of ,argelander's charts and the fainter stars of the ,milky ,way shows1 as ,easton points out1 that ,herschel's hypothesis of a uniform distribution of stars of approximately equal size is quite untenable4 ,it has been suggested that the ,milky ,way may perhaps form a ring of stars with the sun placed nearly1 but not exactly1 in the centre of the ring4 ,but were it really a ring of uniform width with the sun eccentrically placed within it1 we should expect to find the ,milky ,way wider at its nearest part1 and gradually narrowing towards the opposite point4 ,now1 ,herschel's gages and ,celoria's counts show that the ,galaxy is wider in ,aquila than in ,monoceros4 ,this is confirmed by ,easton1 who says1 for the faint stars taken as a whole1 the ,milky ,way is widest in its brightest part 7the italics are ,easton's74 ,from this we should conclude that the ,milky ,way is nearer to us in the direction of ,aquila than in that of ,monoceros4 ,sir ,john ,herschel suggested that the southern parts of the galactic zone are nearer to us on account of their greater brightness in those regions4#dgb ,but greater width is a safer test of distance than relative brightness4 ,for it may be easily shown than the intrinsic brightness of an area containing a large number of stars would be the same for all distances 7neglecting the supposed absorption of light in space74 ,for suppose any given area crowded with stars to be removed to a greater distance4 ,the light of each star would be diminished inversely as the square of the distance4 ,but the given area would also be diminished directly as the square of the distance1 so we should have a diminished amount of light on an equally diminished area1 and hence the intrinsic brightness1 or luminosity of the area per unit of surface1 would remain unaltered4 ,the increased brightness of the ,milky ,way in ,aquila is accounted for by the fact that ,herschel's gages show an increased number of stars1 and hence the brightness in ,aquila and ,sagittarius does not necessarily imply that the ,milky ,way is nearer to us in those parts1 but that it is richer in small stars than in other regions4 ,easton is of opinion that the annular hypothesis of the ,milky ,way is inconsistent with our present knowledge of the galactic phenomena1 and he suggests that its actual constitution resembles more that of a spiral nebula4#dgc ,on this hypothesis the increase in the number of stars in the regions above referred to may be due to our seeing one branch of the supposed two-branched spiral projected on another branch of the same spiral4 ,this seems supported by ,sir ,john ,herschel's observations in the southern hemisphere1 where he found in some places a tissue as it were of large stars spread over another of very small ones1 the immediate magnitudes being wanting4 ,again1 portions of the spiral branches may be richer than others1 as photographs of spiral nebul seem to indicate4 ,celoria1 rejecting the hypothesis of a single ring1 suggests the existence of two galactic rings inclined to each other at an angle of about #bj1 one of these including the brighter stars1 and the other the fainter4 ,but this seems to be a more artificial arrangement then the hypothesis of a spiral4 ,further1 the complicated structure of the ,milky ,way cannot be well explained by ,celoria's hypothesis of two distinct rings one inside the other4 ,from analogy the spiral hypothesis seems much more probable4 ,considering the ,milky ,way to represent a colossal spiral nebula viewed from a point not far removed from the centre of the spiral branches1 ,easton suggests that the bright region between ,greek3 b and ,greek3 g ,cygni1 which is very rich in comparatively bright stars1 may possibly represent the central accumulations of the ,milky ,way1 that is1 the portion corresponding to the nucleus of a spiral nebula4 ,if this be so1 this portion of the ,milky ,way should be nearer to us than others4 ,easton also thinks that the so-called solar cluster of ,gould1 ,kapteyn1 and ,schiaparelli may perhaps be the expression of the central condensation of the galactic system itself1 composed of the most part of suns comparable with our own1 and which would thus embrace most of the bright stars to the #ith or #ajth magnitude4 ,the distance of the galactic streams and convolutions would thus be comparable with the distances of these stars4 ,he thinks that the sun lies within a gigantic spiral1 in a comparatively sparse region between the central nucleus and ,orion4 ,scheiner thinks that the irregularities of the ,milky ,way1 especially in streams1 can be quite well accounted for1 as ,easton has attempted to do1 if they are regarded as a system of spirals1 and not as a ring system4 ,evidence in favour of the spiral hypothesis of the ,milky ,way1 as advocated by ,easton and ,scheiner1 may be found in ,kapteyn's researches on the proper motions of the stars4 ,this eminent astronomer finds that stars with measurable proper motions--and therefore in all probability relatively near the earth--have mostly spectra of the solar type1 and seem to cluster round a point adjacent to the sun1 in total disregard to the position of the ,milky ,way1 and that stars with little or no proper motion collect round the galactic plain4 ,he is also of opinion that the ,milky ,way resembles the ,andromeda nebula1 the globular nucleus representing the solar cluster1 and the far spreading wings or whorls the compressed layer of stars enclosed by the rings of the remote ,galaxy4 ,with reference to the plurality of inhabited worlds1 it has been well said by the ancient writer ,metrodorus 7third century ,b4,c471 ,the idea that there is but a single world in all infinitude would be as absurd as to suppose that a vast field had been formed to produce a single blade of wheat4#dgd ,with this opinion the present writer fully concurs4 ,,chapter ,,xxi ,general ,the achievements of ,hipparchus in astronomy were very remarkable1 considering the age in which he lived4 ,he found the amount of the apparent motion of the stars due to the precession of the equinoxes 7of which he was the discoverer7 to be #ei per annum4 ,the correct amount is about #ej4 ,he measured the length of the year to within #i minutes of its true value4 ,he found the inclination of the ecliptic to the plane of the equator to be #bc #ea'4 ,it was then #bc #df'--;as we now know by modern calculations--so that ,hipparchus' estimation was a wonderfully close approximation to the truth4 ,he computed the moon's parallax to be #eg'1 which is about its correct value4 ,he found the eccentricity of the sun's apparent orbit round the earth to be one twenty-fourth1 the real value being then about one-thirteenth4 ,he determined other motions connected with the earth and moon2 and formed a catalogue of #ajhj stars4 ,all this work has earned for him the well-merited title of ,the ,father of ,astronomy4#dge ,the following is a translation of a ,greek passage ascribed to ,ptolemy3 ,i know that ,i am mortal and the creature of a day1 but when ,i search out the many rolling circles of the stars1 my feet touch the earth no longer1 but with ,zeus himself ,i take my fill of ambrosia1 the food of the gods4#dgf ,this was inscribed 7in ,greek7 on a silver loving cup presented to the late ,professor ,c4 ,a4 ,young1 the famous ,american astronomer4#dgg ,some curious and interesting phenomena are recorded in the old ,chinese ,annals1 which go back to a great antiquity4 ,in #fhg ,b4,c4 a night is mentioned without clouds and without stars 767 ,this may perhaps refer to a total eclipse of the sun2 but if so1 the eclipse is not mentioned in the ,chinese list of eclipses4 ,in the year #ada ,b4,c41 it is stated that the sun and moon appeared of a deep red colour during #e days1 a phenomenon which caused great terror among the people4 ,in #gd ,b4,c41 it is related that a star as large as the moon appeared1 and was followed in its motion by several stars of ordinary size4 ,this probably refers to an unusually large bolide or fireball4 ,in #ch ,b4,c41 a fall of meteoric stones is recorded of the size of a walnut4 ,in ,a4,d4 #hh1 another fall of stones is mentioned4 ,in ,a4,d4 #cba1 sun-spots were visible to the naked eye4 ,homer speaks of a curious darkness which occurred during one of the great battles in the last year of the ,trojan war4 ,mr4 ,stockwell identifies this with an eclipse of the sun which took place on ,august #bh1 #aahd ,b4,c4 ,an eclipse referred to by ,thucydides as having occurred during the first year of the ,peloponnesian ,war1 when the darkness was so great that some stars were seen1 is identified by ,stockwell with a total eclipse of the sun1 which took place on ,august #b1 #dcj ,b4,c4 ,a great eclipse of the sun is supposed to have occurred in the year #dc or #dd ,b4,c41 soon after the death of ,julius ,csar4 ,baron de ,zach and ,arago mention it as the first annular eclipse on record4 ,but calculations show that no solar eclipse whatever1 visible in ,italy1 occurred in either of these years4 ,the phenomenon referred to must therefore have been of atmospherical origin1 and indeed this is suggested by a passage in ,suetonius1 one of the authors quoted on the subject4 ,m4 ,guillaume thinks that the ninth ,egyptian plague1 the thick darkness 7,exodus x4 #ba-bc71 may perhaps be explained by a total eclipse of the sun which occurred in #accb ,b4,c4 ,it is true that the account states that the darkness lasted three days1 but this1 ,m4 ,guillaume thinks1 may be due to an error in the translation4#dgh ,this explanation1 however1 seems very improbable4 ,according to ,hind1 the moon was eclipsed on the generally received date of the ,crucifixion1 ,a4,d4 #cc1 ,april #c4 ,he says1 ,i find she had emerged from the earth's dark shadow a quarter of an hour before she rose at ,jerusalem 7#f;h #cfm p4m472 but the penumbra continued upon her disc for an hour afterwards4 ,an eclipse could not have had anything to do with the darkness over all the land during the ,crucifixion4 ,for this lasted for three hours1 and the totality of a solar eclipse can only last a few minutes at the most4 ,as a matter of fact the eclipse of ,phlegon1 a partial one 7,a4,d4 #bi1 ,november #bd7 was the only solar eclipse that could have been visible in ,jerusalem during the period usually fixed for the ministry of ,christ4 ,it is mentioned in the ,anglo-,saxon ,chronicle that a total eclipse of the sun took place in the year after ,king ,alfred's great battle with the ,danes4 ,now1 calculation shows that this eclipse occurred on ,october #bi1 #hgh ,a4,d4 ,king ,alfred's victory over the ,danes must1 therefore1 have taken place in #hgg ,a4,d41 and his death probably occurred in #hii ,a4,d4 ,this solar eclipse is also mentioned in the ,annals of ,ulster4 ,from this it will be seen that in some cases the dates of historical events can be accurately fixed by astronomical phenomena4 ,it is stated by some historians that an eclipse of the sun took place on the morning of the battle of ,crecy1 ,august #bf1 #acdf4 ,but calculation shows that there was no eclipse of the sun visible in ,england in that year4 ,at the time of the famous battle the moon had just entered on her first quarter1 and she was partially eclipsed six days afterwards--that is on the #ast of ,september4 ,the mistake seems to have arisen from a mistranslation of the old ,french word esclistre1 which means lightning4 ,this was mistaken for esclipse4 ,the account seems to indicate that there was a heavy thunderstorm on the morning of the battle4 ,a dark shade was seen on the waning moon by ,messrs4 ,hirst and ,j4 ,c4 ,russell on ,october #ba1 #ahgh1 as dark as the shadow during an eclipse of the moon4#dgi ,if this observation is correct1 it is certainly most difficult to explain4 ,another curious observation is recorded by ,mr4 ,e4 ,stone ,wiggins1 who says that a partial eclipse of the sun by a dark body was observed in the ,state of ,michigan 7,u4,s4,a47 on ,may #af1 #ahhd1 at #g p4m4 ,the moon at that moment was #ab degrees south of the equator and the sun as many degrees north of it4 ,the existence of a dark satellite of the earth has been suggested1 but this seems highly improbable4 ,the sun's corona seems to have been first noticed in the total eclipse of the sun which occurred at the death of the ,roman emperor ,domitian1 ,a4,d4 #ie4 ,philostratus in his ,life of ,apollonius says1 with reference to this eclipse1 ,in the heavens there appeared a prodigy of this nature3 a certain corona resembling the ,iris surrounded the orb of the sun1 and obscured its light4#dhj ,in more modern times the corona seems to have been first noticed by ,clavius during the total eclipse of ,april #i1 #aefg4dha ,kepler proved that this eclipse was total1 not annular1 so that the ring seen by ,clavius must have been the corona4 ,with reference to the visibility of planets and stars during total eclipses of the sun2 in the eclipse of ,may #ab1 #agjf1 ,venus1 ,mercury1 and ,aldebaran1 and several other stars were seen4 ,during the totality of the eclipse of ,may #c1 #agae1 about twenty stars were seen with the naked eye4#dhb ,at the eclipse of ,may #bb1 #agbd1 ,venus and ,mercury1 and a few fixed stars were seen4#dhc ,the corona was also noticed4 ,at the eclipse of ,may #b1 #agcc1 ,jupiter1 the stars of the ,plough1 ,capella1 and other stars were visible to the naked eye2 and the corona was again seen4#dhc ,during the total eclipses of ,february #i1 #agff1 ,june #bd1 #aggh1 and ,june #af1 #ahjf1 the corona was again noticed4 ,but its true character was then unknown4 ,at the eclipse of ,july #h1 #ahdb1 it was noticed by observers at ,lipesk that the stars ,aldebaran and ,betelgeuse 7,greek3 a ,orionis71 which are usually red1 appeared quite white4#dhd ,there will be seven eclipses in the years #aiag1 #aice1 and #aihe4 ,in the year #aice there will be five eclipses of the sun1 a rare event2 and in #aihe there will be three total eclipses of the moon1 a most unusual occurrence4#dhe ,among the ancient ,hindoos1 the common people believed that eclipses were caused by the interposition of a monstrous demon called ,raha4 ,this absurd idea1 and others equally ridiculous1 were based on declarations in their sacred books1 and no pious ,hindoo would think of denying it4 ,the following cases of darkenings of the sun are given by ,humboldt3-- ,according to ,plutarch the sun remained pale for a whole year at the death of ,julius ,csar1 and gave less than its usual heat4#dhf ,a sun-darkening lasting for two hours is recorded on ,august #bb1 #ceh ,a4,d41 before the great earthquake of ,nicomedia4 ,in #cfj ,a4,d4 there was a sun-darkening from early morn till noon4 ,the description given by the historians of the time corresponds to an eclipse of the sun1 but the duration of the obscurity is inexplicable4 ,in #dji ,a4,d41 when ,alaric lay siege to ,rome1 there was so great a darkness that the stars were seen by day4 ,in #ecf ,a4,d4 the sun is said to have been darkened for a year and two months6 ,in #fbf ,a4,d41 according to ,abul ,farag1 half the sun's disc was darkened for eight months6 ,in #icd ,a4,d4 the sun lost its brightness for two months in ,portugal4 ,in #ajij ,a4,d4 the sun was darkened for three hours4 ,in #ajif1 sun-spots were seen with the naked eye on ,march #c4 ,in #abjf ,a4,d4 on the last day of ,february1 there was complete darkness for six hours1 turning the day into night4 ,this seems to have occurred in ,spain4 ,in #abda the sun was so darkened that stars could be seen at #c p4m4 on ,michaelmas day4 ,this happened in ,vienna4#dhg ,the sun is said to have been so darkened in the year #aedg ,a4,d4 for three days that stars were visible at midday4 ,this occurred about the time of the battle of ,mhlbergh4#dhh ,some of these darkenings may possibly have been due to an enormous development of sun-spots2 but in some cases the darkness is supposed by ,chladni and ,schnurrer to have been caused by the passage of meteoric masses before the sun's disc4 ,the first observer of a transit of ,venus was ,jeremiah ,horrocks1 who observed the transit of ,november #bd 7,o4,s471 #afci4 ,he had previously corrected ,kepler's predicted time of the transit from #h;h #hm a4m4 at ,manchester to #e;h #egm p4m4 ,at the end of #ahge a marble scroll was placed on the pedestal of the monument of ,john ,conduitt 7nephew of ,sir ,isaac ,newton1 and who adopted ,horrocks' theory of lunar motions7 at the west end of the nave of ,westminster ,abbey1 bearing this inscription from the pen of ,dean ,stanley-- ,ad majora avocatus qu ob hc parerga negligi non decuit ,,in ,,memory ,,of ,,jeremiah ,,horrocks ,curate of ,hoole in ,lancashire ,who died on the #c;d of ,january1 #afda1 in or near his #bb;d year ,having in so short a life ,detected the long inequality in the mean motion of ,jupiter and ,saturn ,discovered the orbit of the ,moon to be an ellipse2 ,determined the motion of the lunar aspe1 ,suggested the physical cause of its revolution2 ,and predicted from his own observations1 the ,transit of ,venus ,which was seen by himself and his friend ,,william ,,crabtree ,on ,sunday1 the #bdth ,november 7,o4,s47 #afci2 ,this ,tablet1 facing the ,monument of ,newton ,was raised after the lapse of more than two centuries ,december #i1 #ahgd4dhi ,the transit of ,venus which occurred in #agfa was observed on board ship767 by the famous but unfortunate ,french astronomer ,le ,gentil4 ,the ship was the frigate ,sylphide1 sent to the help of ,pondicherry 7,india7 which was then being besieged by the ,english4 ,owing to unfavourable winds the ,sylphide was tossed about from ,march #be1 #agfa1 to ,may #bd of the same year4 ,when1 on the later date1 off the coast of ,malabar1 the captain of the frigate learned that ,pondicherry had been captured by the ,english1 the vessel returned to the ,isle of ,france1 where it arrived on ,june #bc1 after touching at ,point de ,galle on ,may #cj4 ,it was between these two places that ,le ,gentil made his observations of the transit of ,venus under such unfavourable conditions4 ,he had an object-glass of #ae feet 7,french7 focus1 and this he mounted in a tube formed of four pine planks4 ,this rough instrument was fixed to a small mast set up on the quarter-deck and worked by ropes4 ,the observations made under such curious conditions1 were not1 as may be imagined1 very satisfactory4 ,as another transit was to take place on ,june #c1 #agfi1 ,le ,gentil made the heroic resolution of remaining in the southern hemisphere to observe it6 ,this determination was duly carried out1 but his devotion to astronomy was not rewarded2 for on the day of the long waited for transit the sky at ,pondicherry 7where he had gone to observe it7 was clouded over during the whole phenomenon1 although for many days previous the sky had been cloudless4 ,to add to his feeling of disappointment he heard that at ,manilla1 where he had been staying some time previously1 the sky was quite clear1 and two of his friends there had seen the transit without any difficulty4#dij ,truly the unfortunate ,le ,gentil was a martyr to science4 ,the famous ,german astronomer ,bessel once said that a practical astronomer could make observations of value if he had only a cart-wheel and a gun barrel2 and ,watson said that the most important part of the instrument is the person at the small end4#dia ,with reference to ,father ,hell's supposed forgery of his observations of the transit of ,venus in #agfi1 and ,littrow's criticism of some of the entries in ,hell's manuscript being corrected with a different coloured ink1 ,professor ,newcomb ascertained from ,weiss that ,littrow was colour blind1 and could not distinguish between the colour of ,aldebaran and the whitest star4 ,newcomb adds1 ,for half a century the astronomical world had based an impression on the innocent but mistaken evidence of a colour-blind man respecting the tint of ink in a manuscript4 ,it is recorded that on ,february #bf1 ,b4,c4 #bjab1 the moon1 ,mercury1 ,venus1 ,jupiter1 and ,saturn1 were in the same constellation1 and within #ad degrees of each other4 ,on ,september #ad1 #aahf ,a4,d41 the sun1 moon1 and all the planets then known1 are said to have been situated in ,libra4#dib ,in the ,sanscrit epic poem1 ,the ,ramaya1 it is stated that at the birth of ,rama1 the moon was in ,cancer1 the sun in ,aries1 ,mercury in ,taurus1 ,venus in ,pisces1 ,mars in ,capricornus1 ,jupiter in ,cancer1 and ,saturn in ,libra4 ,from these data1 ,mr4 ,walter ,r4 ,old has computed that ,rama was born on ,february #aj1 #agfa ,b4,c4#dic ,a close conjunction of ,mars and ,saturn was observed by ,denning on ,september #bi1 #ahhi1 the bright star ,regulus 7,greek3 a ,leonis7 being at the time only #dg' distant from the planets4#did ,an occultation of the ,pleiades by the moon was observed by ,timocharis at ,alexandria on ,january #bi1 #bhb ,b4,c4 ,calculations by ,schjellerup show that ,alcyone 7,greek3 ,tauri7 was occulted2 but the exact time of the day recorded by ,timocharis differs very considerably from that computed by ,schjellerup4#die ,another occultation of the ,pleiades is recorded by ,agrippa in the reign of ,domitian4 ,according to ,schjellerup the phenomenon occurred on ,november #bi1 ,a4,d4 #ib4 ,kepler states that on the #ith of ,january1 #aeia1 ,mstlin and himself witnessed an occultation of ,jupiter by ,mars4 ,the red colour of the latter on that occasion plainly indicated that it was the inferior planet4#dif ,that is1 that ,mars was nearer to the sun than ,jupiter4 ,but as the telescope had not then been invented1 this may have been merely a near approach of the two planets4 ,according to ,kepler1 ,mstlin saw an occultation of ,mars by ,venus on ,october #c1 #aeij4 ,but this may also have been merely a near approach4#dif ,a curious paradox is that one can discover an object without seeing it1 and see an object without discovering it6 ,the planet ,neptune was discovered by ,adams and ,leverrier by calculation before it was seen in the telescope by ,galle2 and it was actually seen by ,lalande on ,may #h and #aj1 #agie1 but he took it for a star and thus missed the discovery4 ,in fact1 he saw the planet1 but did not discover it4 ,it actually appears as a star of the #hth magnitude in ,harding's ,atlas 7#ahbb74 ,the great new star of ,february1 #aija1 known as ,nova ,persei1 was probably seen by some people before its discovery was announced2 and it was actually noticed by a well-known ,american astronomer1 who thought it was some bright star with which he was not familiar6 ,but this did not amount to a discovery4 ,any one absolutely ignorant of astronomy might have made the same observation4 ,an object must be identified as a new object before a discovery can be claimed4 ,some years ago a well-known ,irish naturalist discovered a spider new to science1 and after its discovery he found that it was common in nearly every house in ,dublin6 ,but this fact did not detract in the least from the merit of its scientific discovery4 ,there is a story of an eminent astronomer who had been on several eclipse expeditions1 and yet was heard to remark that he had never seen a total eclipse of the sun4 ,but your observations of several eclipses are on record1 it was objected4 ,certainly1 ,i have on several occasions made observations1 but ,i have always been too busy to look at the eclipse4 ,he was probably in a dark tent taking photographs or using a spectroscope during the totality4 ,this was observing an eclipse without seeing it6 ,humboldt gives the credit of the invention of the telescope to ,hans ,lippershey1 a native of ,wesel and a spectacle-maker at ,middleburgh2 to ,jacob ,adreaansz1 surnamed ,metius1 who is also said to have made burning-glasses of ice2 and to ,zachariah ,jansen4#dig ,with reference to the parabolic figure of the large mirrors of reflecting telescopes1 ,dr4 ,robinson remarked at the meeting of the ,british ,association at ,cork in #ahdc1 between the spherical and parabolic figures the extreme difference is so slight1 even in the telescope of #f-;feet aperture ,lord ,rosse's that if the two surfaces touched at their vertex1 the distance at the edge would not amount to the #a_/ajjjjth of an inch1 a space which few can measure1 and none without a microscope4#dih ,in the year #ageh1 ,roger ,long1 ,lowndean ,professor of ,astronomy at ,cambridge1 constructed an orrery on a novel principle4 ,it was a hollow metal sphere of about #ah feet in diameter with its fixed axis parallel to the earth's axis4 ,it was rotated1 by means of a winch and rackwork4 ,it held about thirty persons in its interior1 where astronomical lectures were delivered4 ,the constellations were painted on the interior surface2 and holes pierced through the shell and illuminated from the outside represented the stars according to their different magnitudes4 ,this ingenious machine was much neglected for many years1 but was still in existence in ,admiral ,smyth's time1 #ahdd4dii ,a temporary star is said to have been seen by ,hepidanus in the constellation ,aries in either #ajjf or #ajab ,a4,d4 ,the late ,m4 ,schnfeld1 a great authority on variable stars1 found from an ,arabic and ,syrian chronicle that #ajab is the correct year 7#cif of the ,hegira71 but that the word translated ,aries would by a probable emendation mean ,scorpio4 ,the word in the ,syrian record is not the word for ,aries4#ejj ,mr4 ,heber ,d4 ,curtis finds that the faintest stars mentioned in ,ptolemy's ,catalogue are about #ech magnitude on the scale of the ,harvard ,photometric ,durchmustering4#eja ,heis and ,houzeau saw stars of #f-g magnitude 7about #fd on ,harvard scale74 ,the present writer found that he could see most of ,heis' faintest stars in the west of ,ireland 7,co4 ,sligo7 without optical aid 7except short-sighted spectacles74 ,with reference to the apparent changes in the stellar heavens produced by the precession of the equinoxes1 ,humboldt says-- ,canopus was fully #a #bj' below the horizon of ,toledo 7#ci #ed' north latitude7 in the time of ,columbus2 and now the same star is almost as much above the horizon of ,cadiz4 ,while at ,berlin1 and in northern latitudes1 the stars of the ,southern ,cross1 as well as ,greek3 a and ,greek3 b ,centauri1 are receding more and more from view1 the ,magellanic ,clouds are slowly approaching our latitudes4 ,canopus was at its greatest northern approximation during last century eighteenth1 and is now moving nearer and nearer to the south1 although very slowly1 owing to its vicinity to the south pole of the ecliptic4 ,the ,southern ,cross began to become invisible in #eb #cj' north latitude #bijj years before our era1 since1 according to ,galle1 this constellation might previously have reached an altitude of more than #aj4 ,when it had disappeared from the horizon of the countries of the ,baltic1 the great pyramid of ,cheops had already been erected more than five hundred years4 ,the pastoral tribe of the ,hyksos made their incursion seven hundred years earlier4 ,the past seems to be visibly nearer to us when we connect its measurement with great and memorable events4#ejb ,with reference to the great ,grecian philosopher and scientist ,eratosthenes of ,cyrene1 keeper of the ,alexandrian ,library under ,ptolemy ,euergetes1 ,carl ,snyder says1 ,above all the ,alexanders1 ,csars1 ,tadema-,napoleons1 ,i set the brain which first spanned the earth1 over whose little patches these fought through their empty bootless lives4 ,why should we have no poet to celebrate so great a deed8#ejc ,and with reference to ,aristarchus he says1 ,if grandeur of conceptions be a measure of the brain1 or ingenuity of its powers1 then we must rank ,aristarchus as one of the three or four most acute intellects of the ancient world4#ejd ,lagrange1 who often asserted ,newton to be the greatest genius that ever existed1 used to remark also--and the most fortunate2 we do not find more than once a system of the world to establish4#eje ,grant says-- ,lagrange deserves to be ranked among the greatest mathematical geniuses of ancient or modern times4 ,in this respect he is worthy of a place with ,archimedes or ,newton1 although he was far from possessing the sagacity in physical enquiries which distinguished these illustrious sages4 ,from the very outset of his career he assumed a commanding position among the mathematicians of the age1 and during the course of nearly half a century previous to his death1 he continued to divide with ,laplace the homage due to pre-eminence in the exact sciences4 ,his great rival survived him fourteen years1 during which he reigned alone as the prince of mathematicians and theoretical astronomers4#ejf ,a writer in ,nature 7,may #be1 #ahga7 relates the following anecdote with reference to ,sir ,john ,herschel3 ,some time after the death of ,laplace1 the writer of this notice1 while travelling on the continent in company with the celebrated ,french savant ,biot1 ventured to put to him the question1 not altogether a wise one1 ',and whom of all the philosophers of ,europe do you regard as the most worthy successor of ,laplace8' ,probably no man was better able than ,biot to form a correct conclusion1 and the reply was more judicious than the question4 ,it was this1 ',if ,i did not love him so much ,i should unhesitatingly say1 ,sir ,john ,herschel4' ,dr4 ,gill 7now ,sir ,david ,gill71 in an address at the ,cape of ,good ,hope in ,june1 #ahih1 spoke of ,sir ,john ,herschel as the prose poet of science2 his popular scientific works are models of clearness1 and his presidential addresses teem with passages of surpassing beauty4 ,his life was a pure and blameless one from first to last1 full of the noblest effort and the noblest aim from the time when as a young ,cambridge graduate he registered a vow 'to try to leave the world wiser than he found it'--a vow that his life amply fulfilled4#ejg ,prof4 ,newcomb said of ,adams1 the co-discoverer of ,neptune with ,leverrier1 ,adams' intellect was one of the keenest ,i ever knew4 ,the most difficult problem of mathematical astronomy and the most recondite principles that underlie the theory of the celestial motions were to him but child's play4 ,airy he regarded as the most commanding figure in the astronomy of our time4#ejh ,he spoke of ,delaunay1 the great ,french astronomer1 as a most kindly and attractive man1 and says1 ,his investigations of the moon's motion is one of the most extraordinary pieces of mathematical work ever turned out by a single person4 ,it fills two quarto volumes1 and the reader who attempts to go through any part of the calculations will wonder how one man could do the work in a lifetime4#eji ,sir ,george ,b4 ,airy and ,prof4 ,j4 ,c4 ,adams died in the same month4 ,the former on ,january #b1 #ahib1 and the latter on ,january #bb of the same year4 ,it is known from the parish register of ,burstow in ,surrey that ,flamsteed 7,rev4 ,john ,flamsteed71 the first ,astronomer ,royal at ,greenwich1 was buried in the church at that place on ,january #ab1 #agbj2 but a search for his grave made by ,mr4 ,j4 ,carpenter in #ahff and by ,mr4 ,lynn in #ahhj led to no result4 ,in ,mrs4 ,flamsteed's will a sum of twenty-five pounds was left for the purpose of erecting a monument to the memory of the great astronomer in ,burstow ,church2 but it does not appear that any monument was ever erected4 ,flamsteed was ,rector of the ,parish of ,burstow4#eaj ,he was succeeded in #agbj by the ,rev4 ,james ,pound1 another well-known astronomer4 ,pound died in #agbd4eaa ,evelyn says in his ,diary1 #afgf1 ,september #aj1 ,dined with ,mr4 ,flamsteed1 the learned astrologer and mathematician1 whom his ,majesty had established in the new ,observatory in ,greenwich ,park furnished with the choicest instruments4 ,an honest sincere man4#eab ,this shows that in those days the term astrologer was synonymous with astronomer4 ,in an article on ,our ,debt to ,astronomy1 by ,prof4 ,russell ,tracy ,crawford 7,berkeley ,astronomical ,department1 ,california1 ,u4,s4,a471 the following remarks occur3-- ,behind the artisan is a chemist1 behind the chemist is a physicist1 behind the physicist is a mathematician1 and behind the mathematician is an astronomer4 ,were it not for the data furnished by astronomers1 commerce by sea would practically stop4 ,the sailing-master on the high seas could not determine his position1 nor in what direction to head his ship in order to reach a desired harbour4 ,think what this means in dollars and cents1 and estimate it if you can4 ,for this one service alone the science of astronomy is worth more in dollars and cents to the world in one week than has been expended upon it since the beginning of civilization4 ,do you think that ,great ,britain1 for instance1 would take in exchange an amount equal to its national debt for what astronomy gives it8 ,i answer for you most emphatically1 ',no4' ,in his interesting book1 ,reminiscences of an ,astronomer1 ,prof4 ,simon ,newcomb says with reference to the calculations for the ,nautical ,almanac 7referred to in the above extract7-- ,a more hopeless problem than this could not be presented to the ordinary human intellect4 ,there are tens of thousands of men who could be successful in all the ordinary walks of life1 hundreds who could wield empires1 thousands who could gain wealth1 for one who could take up this astronomical problem with any hope of success4 ,the men who have done it are1 therefore1 in intellect the select few of the human race--an aristocracy ranking above all others in the scale of being4 ,the astronomical ephemeris is the last outcome of their productive genius4 ,in a paper on the ,aspects of ,american ,astronomy1 ,prof4 ,newcomb says1 ,a great telescope is of no use without a man at the end of it1 and what the telescope may do depends more upon this appendage than upon the instrument itself4 ,the place which telescopes and observatories have taken in astronomical history are by no means proportional to their dimensions4 ,many a great instrument has been a mere toy in the hands of its owner4 ,many a small one has become famous4 ,twenty years ago there was here in your city ,chicago a modest little instrument which1 judged by its size1 could not hold up its head with the great ones even of that day4 ,it was the private property of a young man holding no scientific position and scarcely known to the public4 ,and yet that little telescope is to-day among the famous ones of the world1 having made memorable advances in the astronomy of double stars1 and shown its owner to be a worthy successor of the ,herschels and ,struves in that line of work4#eac ,here ,prof4 ,newcomb evidently refers to ,prof4 ,burnham1 and the #f-;inch telescope with which he made many of his remarkable discoveries of double stars4 ,with reference to ,burnham's work1 ,prof4 ,barnard says-- ,it represents the labour of a struggling amateur1 who during the day led the drudging life of a stenographer in the ,united ,states court in ,chicago1 and at night worked among the stars for the pure love of it4 ,such work deserves an everlasting fame1 and surely this has fallen to ,mr4 ,burnham4 ,admiral ,smyth says-- ,a man may prove a good astronomer without possessing a spacious observatory3 thus ,kepler was wont to observe on the bridge at ,prague2 ,schrter studied the moon1 and ,harding found a planet from a gloriette2 while ,olbers discovered two new planets from an attic of his house4#ead ,it is probably not generally known that some of the greatest astronomers of modern times1 such as ,kepler1 ,newton1 ,hansen1 ,laplace1 and ,leverrier1 scarcely ever looked through a telescope4#eae ,kepler1 who always signed himself ,keppler in ,german1 is usually supposed to have been born on ,december #ba1 #aega1 in the imperial town of ,weil1 but according to ,baron von ,breitschwert1#eaf he was really born on ,december #bg1 #aega1 in the village of ,magstadt in ,wurtemberg4 ,according to ,lieut4 ,winterhalter1 ,m4 ,perrotin of the ,nice ,observatory declared that two hours' work with a large instrument is as fatiguing as eight with a small one1 the labour involved increasing in proportion to the cube of the aperture1 the chances of seeing decreasing in the same ratio1 while it can hardly be said that the advantages increase in like proportion4#eag ,the late ,mr4 ,proctor has well said-- ,it is well to remember that the hatred which many entertain against the doctrine of development as applied to solar systems and stellar galaxies is not in reality a sign1 as they imagine1 of humility1 but is an effort to avoid the recognition of the nothingness of man in the presence of the infinities of space and time and vitality presented within the universe of ,god4#eah ,humboldt says-- ,that arrogant spirit of incredulity1 which rejects facts without attempting to investigate them1 is in some cases almost more injurious than an unquestioning credulity4 ,both are alike detrimental to the force of investigations4#eai ,with reference to the precession of the equinoxes and the changes it produces in the position of the ,pole ,star1 it is stated in a recent book on science that the entrance passage of the ,great ,pyramid of ,ghizeh is inclined at an angle of #cj to the horizon1 and therefore points to the celestial pole4 ,but this is quite incorrect4 ,the ,great ,pyramid1 it is true1 is situated close to the latitude of #cj4 ,but the entrance passage does not point exactly to the pole4 ,the inclination was measured by ,col4 ,vyse1 and found to be #bf #de'4 ,for six out of the nine pyramids of ,ghizeh1 ,col4 ,vyse found an average inclination of #bf #dg'1 these inclinations ranging from #be #ee' 7#bnd1 or pyramid of ,mycerinus7 to #bh #j' 7#ith pyramid74#ebj ,sir ,john ,herschel gives #cigj ,b4,c4 as the probable date of the erection of the ,great ,pyramid4#ebj ,at that time the distance of ,greek3 a ,draconis 7the ,pole ,star of that day7 from the pole was #c #dd' #be1 so that when on the meridian below the pole 7its lower culmination as it is termed7 its altitude was #cj - #c #dd' #be #bf #ae' #ce1 which agrees fairly well with the inclination of the entrance passage4 ,letronne found a date of #cdcj ,b4,c42 but the earlier date agrees better with the evidence derived from ,egyptology4 ,emerson says-- ,i am brother to him who squared the pyramids ,by the same stars ,i watch4 ,from ,february #f to #ae1 #aijh1 all the bright planets were visible together at the same time4 ,mercury was visible above the western horizon after sunset1 ,venus very brilliant with ,saturn a little above it1 ,mars higher still1 all ranged along the ecliptic1 and lastly ,jupiter rising in the east4#eba ,this simultaneous visibility of all the bright planets is rather a rare occurrence4 ,with reference to the great improbability of ,laplace's original ,nebular ,hypothesis being true1 ,dr4 ,see says1 ,we may calculate from the preponderance of small bodies actually found in the solar system--eight principal planets1 twenty-five satellites 7besides our moon71 and #fbe asteroids--that the chances of a nebula devoid of hydrostatic pressure producing small bodies is about #bfeh to #a1 or a decillion decillion 7#ajff7f to the sixth power1 to unity4 ,this figure is so very large that we shall content ourselves with illustrating a decillion decillion1 and for this purpose we avail ourselves of a method employed by ,,archimedes to illustrate his system of enumeration4 ,imagine sand so fine that #aj1jjj grains will be contained in the space occupied by a poppy seed1 itself about the size of a pin's head2 and then conceive a sphere described about our sun with a radius of #bjj1jjj astronomical units#ebb 7,greek3 a ,centauri being at a distance of #bge1jjj7 entirely filled with this fine sand4 ,the number of grains of sand in this sphere of the fixed stars would be a decillion decillion#ebc 7#ajff7f4 ,all these grains of sand against one is the probability that a nebula devoid of hydrostatical pressure1 such as that which formed the planets and satellites1 will lead to the genesis of such small bodies revolving about a greatly predominant central mass4#ebd ,in other words1 it is practically certain that the solar system was not formed from a gaseous nebula in the manner originally proposed by ,laplace4 ,on the other hand1 the evolution of the solar system from a rotating spiral nebula seems very probable4 99 99 99 99 99 ,some one has said that the world knows nothing of its greatest men4 ,the name of ,mr4 ,george ,w4 ,hill will probably be unknown to many of my readers4 ,but the late ,prof4 ,simon ,newcomb said of him that he will easily rank as the greatest master of mathematical astronomy during the last quarter of the nineteenth century4#ebe ,of ,prof4 ,newcomb himself--also a great master in the same subject--,sir ,robert ,ball says he was the most conspicuous figure among the brilliant band of contemporary ,american astronomers4#ebf ,an astronomer is supposed to say1 with reference to unwelcome visitors to his observatory1 ,who steals my purse steals trash2 but he that filches from me my clear nights1 robs me of that which not enriches him1 and makes me poor indeed4#ebg ,cicero said1 ,in the heavens there is nothing fortuitous1 unadvised1 inconstant1 or variable2 all there is order1 truth1 reason1 and constancy2 and he adds1 ,the creation is as plain a signal of the being of a ,god1 as a globe1 a clock1 or other artificial machine1 is of a man4#ebh ,of all the epigrams attributed rightly or wrongly to ,plato1 the most famous has been expanded by ,shelley into the four glorious lines-- ',thou wert the morning star among the living ,ere thy pure light had fled1 ,now having died1 thou art as ,hesperus1 giving ,new splendour to the dead4'#ebi ,sir ,david ,brewster has well said1#ecj ,isaiah furnishes us with a striking passage1 in which the occupants of the earth and the heavens are separately described1 ',i have made the earth1 and created man upon it3 ,i1 even ,my hands1 have stretched out the heavens1 and all their host have ,i commanded' 7,isaiah xlv4 #ab74 ,but in addition to these obvious references to life and things pertaining to life1 we find in ,isaiah the following remarkable passage3 ',for thus saith the ,lord that created the heavens2 ,god ,himself that formed the earth and made it2 ,he hath established it1 ,he created it not ,,in ,,vain1 ,he formed it to be inhabited' 7,isaiah xlv4 #ah74 ,here we have a distinct declaration from the inspired prophet that the earth would have been created ,,in ,,vain if it had not been formed to be inhabited2 and hence we draw the conclusion that as the ,creator cannot be supposed to have made the worlds of our system and those in the sidereal system in vain1 they must have been formed to be inhabited4 ,this seems to the present writer to be a good and sufficient reply to ,dr4 ,wallace's theory that our earth is the only inhabited world in the ,universe6#eca ,such a theory seems incredible4 ,the recent discovery made by ,prof4 ,kapteyn1 and confirmed by ,mr4 ,eddington1 of two drifts of stars1 indicating the existence of two universes1 seems to render untenable ,dr4 ,wallace's hypothesis of the earth's central position in a single universe4#eca ,,note ,,added ,,in ,,the ,,press4 ,while these pages were in the ,press1 it was announced1 by ,dr4 ,max ,wolf of ,heidelberg1 that he found ,halley's comet on a photograph taken on the early morning of ,september #ab1 #aiji4 ,the discovery has been confirmed at ,greenwich ,observatory4 ,the comet was close to the position predicted by the calculations of ,messrs4 ,cowell and ,crommelin of ,greenwich ,observatory 7,nature1 ,september #af1 #aijh74 ,,index ,a ,aboukir1 #bhg ,aboul ,hassan1 #bba ,abu ,ali al ,farisi1 #bbe ,abu-,hanifa1 #bcc1 #bcd ,abul-fadl1 #bcf ,accadians1 #bej1 #beb ,achernar1 #bge ,aclian1 #bhb ,adam1 #if1 #cdg ,adhad-al-,davlat1 #bbe1 #bcf ,adonis1 #bfa ,adreaansz1 #cdb ,airy1 ,sir ,g4 ,b41 #hg1 #adj1 #cdg1 #ceg ,aitken1 #afj ,al-,battani1 #bcb1 #bcc ,albrecht1 #agc ,albufaragius1 #bhc ,alcor1 #bda ,alcyone1 #acg ,aldebaran1 #fj1 #aef1 #bcf1 #beb1 #beg1 #caj1 #caa ,alfard1 #bcf1 #bhi ,alfargani1 #bhf ,alfraganus1 #bha ,almagest1 #bha ,al-,sufi1 #dg1 #adi1 #agi1 #ahi1 #bba1 #bbd1 #bbe-bch1 #bdd1 #bdf1 #bej1 #bea1 #bec1 #bed1 #bfa1 #bfc1 #bfd1 #bff-bgj1 #bgb1 #bgd-bgh1 #bhe1 #bhg1 #bhi1 #bij1 #bic1 #bih1 #cjj-cjb1 #cjd1 #cjg ,altair1 #bdf ,ampelius1 #bfb ,amphion1 #beg ,ancient eclipses1 #eb1 #ec ,anderson1 #abj1 #bgg ,andromeda nebula1 #aih-bjf1 #bca ,annals of ,ulster1 #ccb ,antares1 #fj1 #agi1 #caj1 #caa ,anthelm1 #cjj ,antinous1 #bdh ,antlia1 #cjb ,apollo1 #beg ,apparent diameter of moon1 #di ,apple1 #gi ,apples1 golden1 #beh ,apus1 #cjf ,aquarius1 #bfh ,aquila1 #bdf ,aquillus1 #bbj ,ara #bie ,arago1 #bf1 #cj1 #eg1 #aaf1 #aic1 #cca ,aratus1 #bai1 #bdb1 #bde1 #bej1 #bee1 #bef1 #bfa1 #bfc1 #bgb ,archimedes1 #cdf1 #ced ,arcturus1 #adh1 #ahh1 #bdd ,argelander1 #bi1 #bbg1 #bbi1 #bcj1 #bdj ,argo1 #bhe-bhh1 #cje ,argon in sun1 #d ,argonauts1 #bdc1 #bej ,aries1 #bej ,aristotle1 #di1 #fg ,arrhenius1 #d1 #h1 #bb1 #de1 #ff ,ashtoreth1 #bfj ,astra ,borbonia1 #d ,astra1 #bfc ,astronomy1 ,laplace on1 #dd ,astro ,theology1 #bc ,atarid1 #bcb1 #bcc ,atmosphere1 height of1 #cc ,augean stables1 #bfi ,augustus1 #bfb ,auriga1 #bde ,aurora1 #cc1 #da1 #db ,auwers1 #bjf ,axis of ,mars1 #ei ,b ,babilu1 #bfg ,baily1 #acg1 #add ,baker1 #ahc ,ball1 ,sir ,robert1 #f1 #cee ,barnard1 ,prof41 #bi1 #ed1 #eg1 #gi1 #hj1 #ha1 #he1 #hf1 #ia1 #ic1 #ajc1 #ajd1 #aad1 #acj1 #acb1 #aci1 #aib1 #bac1 #caf1 #cag1 #cej ,barnes1 #gh1 #gi ,bartlett1 #ce1 #cf ,bartschius1 #bif1 #bih ,bauschingen1 #fi1 #gj ,bayer1 #agi1 #bba1 #bgb1 #bhd1 #cji1 #caj ,bayeux ,tapestry1 #aje ,becquerel1 #h ,beehive1 #bei ,beer1 #bj ,bel1 #bej ,bellatrix1 #bec ,benoit1 #bb ,berenice1 #big ,berry1 #be ,bessel1 #cci ,betelgeuse1 #agi1 #bbb1 #bfd ,bianchini1 #ba1 #bb1 #gg ,biela's comet1 #ii ,bifornis1 #bfh ,binary stars1 #afb ,birmingham1 #e1 #aad ,black body1 #c ,blackness of sun-spots1 #f ,blaze star1 #ahj1 #ahd ,bode1 #bgf ,bohlin1 #aii1 #bjj ,bond1 #he ,bond 7,jun471 #gd ,book of the ,dead1 #bfd1 #bgd ,borelly1 #ajc ,boserup1 #bh ,boss1 #aeb ,brah1 ,tycho4 ,see ,tycho ,brah ,brauner1 #baa ,bravais1 #db ,bredikhin1 #gf ,bremiker1 #id ,brenner1 ,lo1 #ac1 #bb1 #hg1 #ia1 #acc ,brewster1 #cef ,brightness of ,mercury1 #aj-ab of nebul1 #aic of sun1 #a1 #b1 #c of ,venus1 #ad1 #ag1 #ai1 #ca ,bright clouds1 #cc1 #cd night1 #de stars1 #bgh ,brooks1 #aah ,brown1 #bah1 #bai1 #bdh1 #bee1 #bfj1 #bfg1 #bgb1 #bgi1 #bha1 #bia1 #bie ,browning1 #be ,brugsch1 #abg ,buddha1 #bef ,bull1 ,pope's1 #ajg ,bull's foot1 #bec ,buonaparte1 #cj ,burnham1 #afj1 #afe-afg1 #ahj1 #ahd1 #bfj1 #cej1 #cea ,burns1 #acj ,buss1 #d ,c ,caaba1 #abe ,cacciatore1 #gb ,clum1 #cjb ,callimachus1 #big ,callixtus ,,iii41 #ajg ,calvisius1 #ec ,camelopardalis1 #bif ,cameron1 #ah ,campbell1 #he1 #aec1 #aei1 #agh ,canals on ,mars1 #fa-fc ,cancer1 #beh1 #bei ,canes ,venatici1 #bif ,canicula1 #bhj ,canis ,major1 #bgi ,minor1 #bhd ,canopus1 #aeg1 #bhf1 #cdd ,capella1 #aef1 #afd1 #ahi1 #bcf1 #bde1 #bdf ,capricornus1 #bfg1 #bfh ,capture of satellites1 #eh ,carbonic acid1 #ff ,cassini1 #bj1 #bb1 #gd1 #gh1 #ceh ,cassiopeia's ,chair1 #bdd ,castor1 #afj1 #beg ,caswell1 #eb ,catullus1 #big ,caussin1 #bbe ,cecrops1 #bfh ,celestial ,rivers1 #cjh ,celoria1 #cbd1 #cbf ,centaurus1 #bib1 #bic ,centre of gravity1 #h ,cephalus1 #bgi ,cepheid variables1 #ahg ,ceraski1 #b1 #agf ,cerberus1 #bdc1 #beg ,ceres1 #bfj ,cerulli1 #bb1 #fb ,cetus1 #bgb ,chacornac1 #ah1 #hd ,chamlion1 #cje ,chamberlin1 #aid ,chambers1 #gb ,charles' ,wain1 #bdj ,chinese ,annals1 #ai1 #cj1 #aje1 #ahf1 #bbc1 #bfg1 #ccj ,childrey1 #abh ,chiron1 #bie ,christmann1 #bha ,chromosphere1 sun's1 #d ,cicero1 #di1 #bfb1 #bhj1 #cee ,circinus1 #cjg ,clavius1 #ccd ,climate1 #de ,coal ,sack1 #bic1 #cbj ,cobham1 #hh1 #ajb ,colbert1 #age ,colours of stars1 #adj1 #ada1 #ahh-aij ,coma ,berenices1 #big1 #bih ,comets1 number of1 #ih tails of1 #aae1 #aaf ,comet years1 #ajd ,comiers1 #ii ,comstock1 #ij1 #adf ,condamine1 #beg ,conon1 #big ,coon ,butte mountain1 #abj1 #aba ,cooper1 #c ,copeland1 #gf1 #aeg ,corona1 sun's1 #a1 #ccd round moon1 #ce1 #cf ,corona ,australis1 #bie ,corvinus1 #bib ,corvus1 #bib ,cotsworth1 #df ,cowell1 #aje ,crabtree1 #ccg ,crater1 #bia ,craters on moon1 #ee1 #ef ,crawford1 #cdh ,crecy1 ,battle of1 #ccc ,crescent of ,venus1 #ai1 #bj ,crommelin1 #aje1 #aaa ,crucifixion1 #ah ,curtis1 #cdd ,cusps of ,venus1 #bj ,cygnus1 7#fa71 #aee ,cynocephalus1 #bbb ,d ,dante1 #aef1 #beh1 #bfe ,dark shade on moon1 #ccc ,d',arrest1 #id ,darwin1 ,sir ,george1 #aeh1 #cai ,david's ,chariot1 #bda ,davis1 #aee ,dawes1 #afh ,dawn proclaimer1 #bea ,delambre1 #ahe ,delauney1 #cdg ,dembowski1 #aij ,demetrius1 #aaa ,denning1 #aa1 #gd1 #gg1 #hd1 #hf1 #hg1 #hi1 #ii1 #aah1 #cdj ,derham1 #ba1 #bc ,deucalion1 #bfh ,de ,vico1 #ba1 #bb ,diamonds in meteorites1 #abg ,dilkur1 #bea ,diodorus ,siculus1 #abg ,diogenes ,laertius1 #da ,diomed1 #bgb ,dione1 #hi ,dipper1 #bda ,doberck1 #afj ,dollond1 #bd ,domitian1 #ccd ,donati's comet1 #ajj ,dorado1 #cjd ,dordona1 #bef ,dorn1 #bde ,douglass1 #ha ,dragon1 #bdb ,draper1 #ge ,drayton1 #aef ,dreyer1 #aae ,drifting stars1 #aeb ,dryden1 #bdb ,duncan1 #ahg ,dunlop1 #bfd ,dupret1 #hc ,dupuis1 #bde1 #beb1 #beg1 #beh1 #bei1 #bff1 #bfg1 #bfh ,dusky star1 #bgb ,e ,earthen jar1 #bdg ,earth's attraction on moon1 #ee ,earth's motions1 #ci rotation1 #df surface1 #cb ,earthshine on moon1 #ea1 #eb1 #ef1 #eg ,eastmann1 #caf ,easton1 #cbc1 #cbd1 #cbe ,eclipses1 ancient1 #eb1 #ec1 #eg1 #eh dark1 of moon1 #ec1 #eg1 #eh ,ecliptic1 obliquity of1 #dg ,eddington1 #ceg ,electra1 #ai ,elster1 #ci ,emerson1 #cec ,enceladus1 #hi ,encke1 #aac1 #aaf1 #bdj ,ennis1 #ahi ,eratosthenes1 #bej1 #big1 #cde ,eridanus1 #bgd-bgh ,eros1 #fi1 #gj1 #ga ,eta ,argus1 #agg1 #bhg ,eudemus1 #dg ,eudoxus1 #bah1 #bai1 #bbc ,euler1 #ef ,eunomia1 #ga ,europa1 #beb ,f ,fabritius1 #d1 #aja ,fabry1 #a ,faint stars in telescope1 #agf ,false ,cross1 #aef ,famous stars1 #bdf ,fath1 #acj1 #bac ,faye1 #ajj ,february1 ,five ,sundays in1 #cf ,fergani1 #ahi ,fisher ,stars1 #bef ,fishes in ,andromeda1 #bdi ,fitzgerald1 #abg ,flammarion1 #bb1 #bf1 #ej1 #ach1 #bee1 #bfe1 #bgf ,flamsteed1 #cdh ,flat earth theory1 #cb ,fomalhaut1 #bga1 #cji1 #caj ,fontana1 #bj ,fontenelle1 #ceg ,forbes1 #hb1 #ie1 #if ,fornax1 #cja ,fournier1 #hg ,fovea1 #bhd ,freeman1 #hh ,frret1 #bbb ,frisby1 #aja ,fritsch1 #ba ,furner1 #afc ,g ,gale1 #gh ,galileo1 #c1 #d1 #hj1 #hb ,galle1 #id1 #cda ,ganymede1 #bfh ,gaseous nebula1 spectra of1 #aie-aih1 #bab ,gassendi1 #ad1 #aci ,gathman1 #aah ,gaubil1 #ii ,gauthier1 #ajc ,gegenschein1 #aca ,gemini1 #beg1 #beh ,geminid variables1 #ahg ,gentil1 ,le1 #cch1 #cci ,gertel1 #ci ,ghizeh1 ,pyramids of1 #cec ,gibbous phase of ,jupiter1 #ge ,gill1 ,sir ,david1 #aah1 #bae1 #baf1 #cdf ,glacial epoch1 #db ,gledhill1 #gf ,globular clusters1 #bad1 #bae ,goad1 #ab ,goatcher1 #agi ,golden apples1 #beh ,golius1 #bha ,gould1 #bbi1 #bgh1 #cja1 #cjd1 #cji1 #caj1 #cbf ,grant1 #hb1 #if1 #cde ,gravitation1 ,law of1 #ae1 #dj ,greely1 #ahf ,greisbach1 #hj ,groombridge #ahcj1 #aei ,grubb1 ,sir ,howard1 #afd ,gruithuisen1 #ba1 #be1 #bf1 #bh ,gruson1 #abg ,guillaume1 #cca ,guthrie1 #be ,h ,habitability of ,mars1 #fc-ff of planets1 #dj ,hadrian1 #bdh ,halbert1 #gh ,hale1 #adh1 #aej ,hall1 #ae1 #aca ,halley1 #ad1 #ag1 #ii1 #aje1 #ajf1 #ajh1 #aji1 #aaf1 #adc1 #ade1 #bgf ,halm1 #abb ,halo1 #ce1 #cf ,hanouman1 #bhd ,hansen1 #cea ,hansky1 #bg ,harding1 #be1 #bf1 #id ,harris1 ,mrs41 #ij ,hartwig1 #hh1 #agc ,harvests1 #ajd ,heat of sun1 #b1 #c1 #g ,height of atmosphere1 #cc ,heis1 #acb1 #age1 #ahi1 #bbg1 #bbi1 #cdd ,helium1 #d ,hepidanus1 #bfg1 #cdh ,hercules1 #bdc1 #bei1 #bfh ,herod1 #ah1 #ec ,herschel1 ,miss ,caroline1 #aic1 #aid1 #cbd1 #ceg ,herschel1 ,sir ,john1 #aab1 #agg1 #aij1 #bjg1 #bji1 #baj1 #bae1 #bhi1 #cad1 #cdf1 #cec ,herschel1 ,sir ,wm41 #c1 #bd1 #hj1 #aab1 #aad1 #aae1 #aaf1 #aga1 #agh1 #agi1 #aij1 #cbd1 #cbe ,hesiod1 #ag1 #bbj ,hesperus1 #bef ,hevelius1 #ii1 #aaf1 #bba1 #bif1 #bii1 #cjj ,hill1 #hg1 #cee ,hind1 #ai1 #cj1 #ed1 #aje1 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,society of the ,pacific1 ,august1 #aijh4 #aah ,monthly ,notices1 ,r4,a4,s41 #aijb1 p4 #bia4 #aai ,monthly ,notices1 ,r4,a4,s41 ,february1 #aijb1 p4 #bia4 #abj ,nature1 ,may #bd1 #ahid4 #aba ,ibid41 ,february #ad1 #ahie4 #abb ,ibid41 ,september #ad1 #aije4 #abc ,ibid41 ,september #ba1 #aije4 #abd ,ibid41 ,september #bh1 #aije4 #abe ,ibid41 ,july #ac1 #aije4 #abf ,nature1 ,november #c1 #ahih4 #abg ,ibid41 ,july #ad1 #ahha1 p4 #bce4 #abh ,quoted in ,the ,observatory1 ,february1 #ahif1 p4 #ajd1 from ,ast4 ,nach41 ,no4 #ccai4 #abi ,monthly ,notices1 ,r4,a4,s41 ,february1 #aiji4 #acj ,celestial ,objects1 vol4 i4 p4 #afc4 #aca ,nature1 ,december #bi1 #ahih4 #acb ,celestial ,objects1 vol4 i4 p4 #aff4 #acc ,astrophysical ,journal1 vol4 #ad 7#aija71 pp4 #bdh-i4 #acd ,nature1 ,august #bg1 #aijh4 #ace ,webb's ,celestial ,objects1 vol4 i4 p4 #agg4 #acf ,ibid41 vol4 i4 p4 #ahg4 #acg ,celestial ,objects1 vol4 i4 p4 #ahf4 #ach ,astronomy and ,astrophysics1 #ahib1 p4 #hg4 #aci ,ibid41 #ahib1 pp4 #id-e4 #adj ,observatory1 ,december1 #ahia4 #ada ,popular ,astronomy1 vol4 #aa 7#aijc71 p4 #egd4 #adb ,ibid41 ,october1 #aijh4 #adc ,bulletin1 ,ast4 ,soc4 de ,france1 ,august1 #aijg4 #add ,nature1 ,august1 #bi #aijg4 #ade ,ibid41 ,march #g1 #aijg4 #adf ,bulletin1 ,ast4 ,soc4 de ,france1 ,june1 #aijd4 #adg ,the ,observatory1 ,october1 #aijc1 p4 #cib4 #adh ,astronomy and ,astrophysics1 #ahid1 p4 #bgg4 #adi ,nature1 ,november #ah1 #ahig4 #aej ,journal1 ,b4,a4,a41 ,january1 #aijg4 #aea ,journal1 ,b4,a4,a41 ,february1 #aiji1 p4 #afa4 #aeb ,cosmos1 vol4 ii4 p4 #gjc4 #aec ,ibid4 #aed ,denning1 ,telescopic ,work for ,starlight ,evenings1 p4 #cdi4 #aee ,cosmos1 vol4 iii4 p4 #ge4 #aef ,journal1 ,b4,a4,a41 ,june1 #ahif4 #aeg ,celestial ,objects1 vol4 i4 p4 #aia4 #aeh ,nature1 ,may #cj1 #aija4 #aei ,bulletin1 ,ast4 ,soc4 de ,france1 ,august1 #aijj4 #afj ,astronomy and ,astrophysics1 #ahib4 #afa ,astrophysical ,journal1 ,january1 #aijh1 p4 #ce4 #afb ,nature1 ,may #bb1 #aijb4 #afc ,ibid41 ,july #i1 #aijc4 #afd ,ibid41 ,july #af1 #aijc4 #afe ,nature1 ,september #bd1 #aijc4 #aff ,ibid41 ,october #h1 #aijc4 #afg ,astrophysical ,journal1 vol4 #bf 7#aijg71 p4 #fj4 #afh ,nature1 ,january #cj1 #aijh4 #afi ,ibid41 ,october #ae1 #aijh4 #agj ,ibid41 ,october #bi1 #aijh4 #aga ,journal1 ,b4,a4,a41 ,march1 #aijh1 and ,june #bb1 #aijh4 #agb ,nature1 ,june #be1 #aijc4 #agc ,bulletin1 ,ast4 ,soc4 de ,france1 ,june1 #aijd4 #agd ,pop4 ,ast41 vol4 #ab1 pp4 #djh-i4 #age ,nature1 ,august #bi1 #ahhi4 #agf ,astrophysical ,journal1 vol4 #bf 7#aijg71 p4 #fb4 #agg ,bulletin1 ,ast4 ,soc4 de ,france1 ,january1 #aijd4 #agh ,humboldt's ,cosmos1 vol4 iv4 p4 #ecb4 #agi ,copernicus1 vol4 ii4 p4 #fd4 #ahj ,knowledge1 ,may1 #aiji4 #aha ,journal1 ,british ,astronomical ,association1 ,january1 #aiji1 p4 #acb4 #ahb ,ast4 ,nach41 ,no4 #dcjh4 #ahc ,history of ,physical ,astronomy1 p4 #bjd4 #ahd ,smyth's ,celestial ,cycle1 pp4 #baj1 #baa4 #ahe ,poor1 ,the ,solar ,system1 p4 #bgd4 #ahf ,celestial ,cycle1 p4 #bdf4 #ahg ,nature1 ,october #b1 #ahgi4 #ahh ,ibid41 ,may #f1 #ahhj4 #ahi ,ibid41 ,february #ai1 #ahhj4 #aij ,nature1 ,september #cj1 #ahig4 #aia ,nature1 ,august #e1 #ahge4 #aib ,ibid41 ,october #ab1 #ahhb1 and ,copernicus1 vol4 iii4 p4 #he4 #aic ,nature1 ,may #h1 #ahhd4 #aid ,ibid41 ,june #af1 #ahhg4 #aie ,journal1 ,b4,a4,a41 ,december #ac1 #aija4 #aif ,nature1 ,september #bj1 #aijj4 #aig ,ast4 ,nach41 ,no4 #chfh1 and ,nature1 ,march #ab1 #aijc4 #aih ,nature1 ,november #ac1 #aijh4 #aii ,nature1 ,december #g1 #aije4 #bjj ,celestial ,cycle1 p4 #bei4 #bja ,celestial ,cycle1 p4 #bfj4 #bjb ,journal1 ,b4,a4,a41 ,april1 #aijg4 #bjc ,monthly ,notices1 ,r4,a4,s41 ,march1 #aijh4 #bjd ,celestial ,cycle1 p4 #bca4 #bje ,journal1 ,b4,a4,a41 ,july1 #aijh4 #bjf ,popular ,astronomy1 ,october1 #aijh4 #bjg ,cape ,obs41 p4 #dja4 #bjh ,nature1 ,july #b1 #aijh4 #bji ,journal1 ,b4,a4,a41 ,january #bj1 #aiji1 pp4 #abc-d4 #baj ,chambers' ,handbook of ,astronomy1 ,catalogue of ,comets4 #baa ,seneca1 quoted by ,chambers1 ,handbook1 vol4 i4 p4 #eed 7,fourth ,edition74 #bab ,ibid4 #bac ,ibid4 #bad ,ibid41 p4 #ecd4 #bae ,ibid4 #baf ,ma-tuoan-lin1 quoted by ,chambers1 ,handbook1 p4 #egj4 #bag ,astronomy and ,astrophysics1 #ahic1 p4 #gih4 #bah ,the ,observatory1 ,october1 #ahih4 #bai ,grant's ,history of ,physical ,astronomy1 p4 #bic4 #bbj ,ibid41 p4 #bid4 #bba ,humboldt's ,cosmos1 vol4 i4 pp4 #hi1 #ij 7,ott's translation74 #bbb ,celestial ,objects1 vol4 i4 p4 #baa1 footnote4 #bbc ,denning1 ,telescopic ,work for ,starlight ,evenings1 p4 #bdh4 #bbd ,ibid41 p4 #bdh4 #bbe ,ibid41 p4 #bej4 #bbf ,ibid41 p4 #bca4 #bbg ,vol4 iii4 p4 #ajf4 #bbh ,grant's ,history of ,physical ,astronomy1 p4 #bih4 #bbi ,ibid41 p4 #cje4 #bcj ,humboldt's ,cosmos1 vol4 i4 p4 #ie4 #bca ,nature1 ,april #cj1 #aijh4 #bcb ,bulletin1 ,ast4 ,soc4 de ,france1 ,may1 #aijf4 #bcc ,nature1 ,november #bd1 #aijd4 #bcd ,ibid41 ,september #aj1 #ahif4 #bce ,ibid41 ,june #bi1 #ahic4 #bcf ,journal1 ,b4,a4,a41 ,may #bb1 #aijc4 #bcg ,nature1 ,december #ac1 #aijf1 p4 #aei4 #bch ,nature1 ,september #ac1 #aijf4 #bci ,nature1 ,october #ab1 #aije1 p4 #eif4 #bdj ,knowledge1 ,january #ac1 #ahhb4 #bda ,ibid41 ,january #bj1 #ahhb4 #bdb ,popular ,astronomy1 ,june-,july1 #aijh1 p4 #cde4 #bdc ,the ,observatory1 ,march1 #ahif1 p4 #ace4 #bdd ,the ,observatory1 ,february1 #aijj1 pp4 #ajf-g4 #bde ,knowledge1 ,march1 #ahic1 p4 #ea4 #bdf ,ibid41 ,july #c1 #ahhe1 p4 #aa4 #bdg ,cosmos1 vol4 i4 p4 #ajh 7,ott's translation74 #bdh ,ibid41 vol4 i4 p4 #abd4 #bdi ,ibid41 vol4 i4 p4 #aai1 footnote4 #bej ,copernicus1 vol4 i4 p4 #gb4 #bea ,ibid4 #beb ,astrophysical ,journal1 ,june1 #aiji1 pp4 #cgh-i4 #bec ,knowledge1 ,july1 #aiji1 p4 #bfd4 #bed ,quoted by ,miss ,irene ,e4 ,t4 ,warner in ,knowledge1 ,july1 #aiji1 p4 #bfd4 #bee ,the ,observatory1 ,november1 #aijj4 #bef ,or1 ,before the phantom of false morning died 7#dth edition72 ,the ,observatory1 ,september1 #aije1 p4 #cef4 #beg ,the ,observatory1 ,july1 #ahif1 p4 #bgd4 #beh ,journal1 ,b4,a4,a41 ,january #bd1 #aijf4 #bei ,ast4 ,soc4 of the ,pacific1 ,december1 #aijh1 p4 #bhj4 #bfj ,nature1 ,november #a1 #aijf4 #bfa ,ibid41 ,november #bb1 #aijf1 p4 #ic4 #bfb ,nature1 ,august #cj1 #aijf4 #bfc ,cosmos1 vol4 i4 p4 #aca1 footnote4 #bfd ,nature1 ,december #af1 #ahge4 #bfe ,ibid41 ,july #bc1 #ahia4 #bff ,bulletin1 ,ast4 ,soc4 de ,france1 ,april1 #aijc4 #bfg ,bulletin1 ,ast4 ,soc4 de ,france1 ,april1 #aijc4 #bfh ,the ,observatory1 ,may1 #ahif4 ,the italics are ,brenner's4 #bfi ,cosmos1 vol4 iv4 p4 #efc4 #bgj ,for details of this enumeration1 see ,astronomical ,essays1 p4 #bbb4 #bga ,nature1 ,june #aa1 #aijh4 #bgb ,popular ,astronomy1 vol4 #ad 7#aijf71 p4 #eaj4 #bgc ,bedford ,catalogue1 p4 #ecb4 #bgd ,popular ,astronomy1 vol4 #ae 7#aijg71 p4 #aid4 #bge ,popular ,astronomy1 vol4 #ae 7#aijg71 p4 #aie4 #bgf ,bulletin1 ,ast4 ,soc4 de ,france1 ,february1 #aijc4 #bgg ,here ,greek3 ch is probably #ag ,cygni1 ,greek3 ch being the famous variable near it4 #bgh ,popular ,astronomy1 vol4 #ac 7#aijd71 p4 #eji4 #bgi ,astrophysical ,journal1 ,december1 #ahie4 #bhj ,the ,observatory1 ,july1 #ahie1 p4 #bij4 #bha ,celestial ,cycle1 p4 #cjb4 #bhb ,nature1 ,december #ac1 #ahid4 #bhc ,histoire ,celeste1 p4 #baa4 #bhd ,nature1 ,october1 #ahhg4 #bhe ,ibid41 ,august #bi1 #ahhi4 #bhf ,science ,abstracts1 ,february #be1 #aijh1 pp4 #hb1 #hc4 #bhg ,bedford ,catalogue1 pp4 #bbg-h4 #bhh ,knowledge1 ,february #a1 #ahhh4 #bhi ,celestial ,cycle1 p4 #bhj4 #bij ,popular ,astronomy1 ,february1 #aijd4 #bia ,ibid41 vol4 #ae 7#aijg71 p4 #ddd4 #bib ,journal1 ,b4,a4,a41 ,june1 #ahii4 #bic ,astrophysical ,journal1 vol4 #h 7#ahih71 p4 #cad4 #bid ,astrophysical ,journal1 vol4 #h1 p4 #bac4 #bie ,ibid41 vol4 #ag1 ,january to ,june1 #aijb4 #bif ,astronomy and ,astrophysics1 #ahid1 pp4 #efi-gj4 #big ,the ,study of ,stellar ,evolution 7#aijh71 p4 #aga4 #bih ,astrophysical ,journal1 ,january1 #aije4 #bii ,journal1 ,b4,a4,a41 ,june1 #aija4 #cjj ,ast4 ,soc4 of the ,pacific1 ,december1 #aijh4 #cja ,the ,observatory1 ,november1 #aijb1 p4 #cia4 #cjb ,cosmos1 vol4 iv4 p4 #efg 7,ott's translation74 #cjc ,journal1 ,b4,a4,a41 ,february1 #ahih4 #cjd ,the ,observatory1 ,april1 #ahhg4 #cje ,evangeline1 ,part the ,second1 ,,iii4 #cjf ,legend of ,robert1 ,duke of ,normandy4 #cjg ,copernicus1 vol4 iii4 p4 #bca4 #cjh ,ibid41 p4 #fa4 #cji ,cosmos1 vol4 i4 p4 #adb4 #caj ,these apertures are computed from the formula1 minimum visible #i #e log4 aperture4 #caa ,cosmos1 vol4 iii4 p4 #gc4 #cab ,darwin and ,modern ,science1 p4 #efc4 #cac ,journal1 ,b4,a4,a41 ,october1 #ahie4 #cad ,burnham's ,general ,catalogue of ,double ,stars1 p4 #did4 #cae ,journal1 ,b4,a4,a41 ,november #ah1 #ahif4 #caf ,ibid41 ,b4,a4,a41 ,january1 #aijg4 #cag ,studies in ,astronomy1 p4 #ahe4 #cah ,knowledge1 ,june1 #ahia4 #cai ,seen by ,drs4 ,ludendorff and ,eberhard1 ,the ,observatory1 ,april1 #aijf1 p4 #aff1 quoted from ,ast4 ,nach41 ,no4 #djfg4 #cbj ,the ,observatory1 ,january1 #aijg1 p4 #fa4 #cba ,astronomy and ,astrophysics1 #ahid4 #cbb ,smyth's ,celestial ,cycle1 p4 #bbc4 #cbc ,nature1 ,february #g1 #aijg4 #cbd ,ibid41 ,march #ai1 #aijh4 #cbe ,popular ,astronomy1 vol4 #ae 7#aijg71 p4 #i4 #cbf ,astrophysical ,journal1 ,june1 #aijg1 p4 #ccj4 #cbg ,ibid41 vol4 #bb1 p4 #agb4 #cbh ,nature1 ,november #ah1 #ahhf4 #cbi ,astrophysical ,journal1 vol4 #ag 7#aijc71 p4 #bhb4 #ccj ,astrophysical ,journal1 vol4 #ab 7#aijj71 p4 #ed4 #cca ,nature1 ,march #ba1 #ahgh4 #ccb ,bulletin1 ,ast4 ,soc4 de ,france1 ,june1 #aijd4 #ccc ,journal1 ,b4,a4,a41 vol4 #ag 7#aijc71 p4 #bhb4 #ccd ,nature1 ,june #bj1 #aiji4 #cce ,the ,observatory1 vol4 #g 7#ahhd71 p4 #ag4 #ccf ,the ,observatory1 vol4 #ad 7#ahia71 p4 #fi4 #ccg ,astronomy and ,astrophysics1 #ahif1 p4 #ed #cch ,nature1 ,august #bh1 #aijb4 #cci ,astrophysical ,journal1 ,october1 #aijc4 #cdj ,nature1 ,may #cj1 #aijg4 #cda ,popular ,astronomy1 ,february1 #aiji1 p4 #abe4 #cdb ,the ,observatory1 ,may1 #aijg1 p4 #baf4 #cdc ,astrophysical ,journal1 ,may1 #aijg4 #cdd ,histoire de l',astronomie ,moderne1 vol4 i4 pp4 #ahe-f4 #cde ,humboldt's ,cosmos1 vol4 iii4 p4 #baj 7,ott's translation74 #cdf ,ibid41 vol4 iii4 pp4 #bac-ad4 #cdg ,j4 ,c4 ,duncan1 ,lick ,observatory ,bulletin1 ,no4 #aea4 #cdh ,astrophysical ,journal1 vol4 #ag1 p4 #bhc4 #cdi ,the ,origin of the ,stars1 p4 #adc4 #cej ,ibid41 p4 #ace4 #cea ,quoted by ,ennis in ,the ,origin of the ,stars1 p4 #acc4 #ceb ,astrophysical ,journal1 vol4 #bj 7#aijd71 p4 #ceg4 #cec ,nature1 ,march #h1 #aijf4 #ced ,astronomical ,society of the ,pacific1 ,august1 #aijh4 #cee ,astronomy and ,astrophysics1 #ahid1 p4 #hab4 #cef ,the ,observatory1 ,may1 #aije4 #ceg ,this is a misquotation4 ,see my ,astronomical ,essays1 p4 #ace4 #ceh ,nature1 ,february #c1 #ahgj4 #cei ,bedford ,catalogue1 p4 #ad4 #cfj ,ibid41 p4 #cjg4 #cfa ,astrophysical ,journal1 vol4 #ad1 p4 #cg4 #cfb ,ibid41 vol4 #i1 p4 #adi4 #cfc ,nature1 ,july #bj1 #ahii4 #cfd ,ast4 ,nach41 ,no4 #cdgf4 #cfe ,astronomische ,nachrichten1 ,no4 #dbac4 #cff ,astrophysical ,journal1 vol4 #i1 p4 #adi4 #cfg ,cape ,observations1 p4 #fa4 #cfh ,ibid41 p4 #he4 #cfi ,cape ,observations1 p4 #ih4 #cgj ,transactions1 ,royal ,dublin ,society1 vol4 #b4 #cga ,ast4 ,nach41 #cfbh1 quoted in ,the ,observatory1 ,april1 #aijj4 #cgb ,nature1 ,april #h1 #aiji4 #cgc ,problems in ,astrophysics1 p4 #dgg4 #cgd ,ibid41 p4 #dii4 #cge ,copernicus1 vol4 iii4 p4 #ee4 #cgf ,lick ,observatory ,bulletin1 ,no4 #adi4 #cgg ,ibid4 #cgh ,ibid4 #cgi ,monthly ,notices1 ,r4,a4,s41 ,april1 #aijh1 pp4 #dfe-dha4 #chj ,lick ,observatory ,bulletin1 ,no4 #aee 7,february1 #aiji74 #cha ,outlines of ,astronomy1 par4 #hgj 7,edition of #ahge74 #chb ,georgics1 i4 ,,ii4 #bag-ah4 #chc ,see paper by ,mr4 and ,mrs4 ,maunder in ,monthly ,notices1 ,r4,a4,s41 ,march1 #aijd1 p4 #ejf4 #chd ,primitive ,constellations1 vol4 ii4 p4 #adc4 #che ,recherches sur l',histoire de l',astronomie ,ancienne1 by ,paul ,tannery 7#ahic71 p4 #bih4 #chf ,primitive ,constellations1 vol4 ii4 p4 #bbe4 #chg ,nature1 ,october #b1 #ahij4 #chh ,lalande's ,astronomie1 vol4 i4 pp4 #bdc-d4 #chi ,lalande's ,astronomie1 vol4 i4 pp4 #bdb-c4 #cij ,there are three copies of ,al-,sufi's work in the ,imperial ,library at ,paris1 but these are inaccurate4 ,there is also one in the ,british ,museum ,library1 and another in the ,india ,office ,library2 but these are imperfect1 considerable portions of the original work being missing4 #cia ,harvard ,annals1 vol4 ix4 p4 #ea4 #cib ,the science of the risings and settings of the stars was called ilm el-anwa 7,caussin1 ,notices et ,extraits des ,manuscrits de la ,bibliothque due ,roi1 tome xii4 p4 #bcg74 #cic ,see ,mr4 ,e4 ,b4 ,knobel's papers on this subject in the ,monthly ,notices1 ,r4,a4,s41 for #ahgi and #ahhd4 #cid ,in reading this chapter the reader is recommended to have a ,star ,atlas beside him for reference2 ,proctor's smaller ,star ,atlas will be found very convenient for this purpose4 ,on the title-page of this useful work the author quotes ,carlyle's words1 ,why did not somebody teach me the constellations and make me at home in the starry heavens which are always overhead1 and which ,i don't half know to this day8 #cie ,bedford ,catalogue1 p4 #bi4 #cif ,cosmos1 vol4 iii4 p4 #hg4 #cig ,heavenly ,display1 #egi-he4 #cih ,bedford ,catalogue1 p4 #che4 #cii ,lalande's ,astronomie1 vol4 iv4 p4 #ebi4 #djj ,lalande's ,astronomie1 vol4 i4 pp4 #bfh-i4 #dja ,primitive ,constellations1 vol4 i4 p4 #dh4 #djb ,bedford ,catalogue1 pp4 #bg1 #bh4 #djc ,lalande's ,astronomie1 vol4 iv4 p4 #dib4 #djd ,bedford ,catalogue1 p4 #abj4 #dje ,primitive ,constellations1 vol4 i4 p4 #adc4 #djf ,perseus4 #djg ,heavenly ,display1 #bed-h1 #bfa-e1 quoted by ,brown in ,primitive ,constellations1 vol4 i4 p4 #bgd4 #djh ,lalande's ,astronomie1 vol4 iv4 p4 #dic4 #dji ,primitive ,constellations1 vol4 i4 p4 #bib4 #daj ,paradiso1 xxii4 #aaa4 #daa ,lalande's ,astronomie1 vol4 iv4 p4 #dic4 #dab ,bedford ,catalogue1 p4 #bbe4 #dac ,nature1 ,april #f1 #ahhb4 #dad ,primitive ,constellations1 vol4 i4 p4 #fh4 #dae ,ibid41 vol4 i4 p4 #ga4 #daf ,bibliographie ,gnrale de l',astronomie1 vol4 i4 ,introduction1 pp4 #aca1 #acb4 #dag ,lalande's ,astronomie1 vol4 i4 p4 #bif4 #dah ,primitive ,constellations1 vol4 i4 p4 #gd4 #dai ,cape ,observations1 p4 #aaf4 #dbj ,metamorphoses1 xv4 #cga4 #dba ,lalande's ,astronomie1 vol4 iv4 p4 #dhg4 #dbb ,monthly ,notices1 ,r4,a4,s41 ,april #ad1 #ahdh4 #dbc ,prim4 ,const41 vol4 ii4 p4 #de4 #dbd ,lalande's ,astronomie1 pp4 #dgb-c4 #dbe ,lalande's ,astronomie1 vol4 iv4 p4 #dhe4 #dbf ,this star is not shown in ,proctor's small ,atlas1 but it lies between ,greek3 m and ,greek3 n1 nearer to ,greek3 m4 #dbg ,lalande's ,astronomie1 vol4 i4 p4 #bdg4 #dbh ,lalande's ,astronomie1 vol4 iv4 p4 #dhi4 #dbi ,primitive ,constellations1 vol4 i4 p4 #ia4 #dcj ,memoirs1 ,r4,a4,s41 vol4 xiii4 #fa4 #dca ,monthly ,notices1 ,r4,a4,s41 ,june1 #ahie4 #dcb ,lalande's ,astronomie1 vol4 i4 p4 #bgd4 #dcc ,primitive ,constellations1 vol4 i4 p4 #adc4 #dcd ,primitive ,constellations1 vol4 i4 p4 #bgh4 #dce ,lalande's ,astronomie1 vol4 iv4 p4 #dfh4 #dcf ,qust4 ,nat41 ,lib4 #a1 ,cap4 ,i4 #f2 quoted by ,dr4 ,see4 ,canicula is ,sirius1 and ,nartis1 ,mars4 #dcg ,astronomy and ,astrophysics1 vol4 #aa1 #ahib4 #dch ,the ,observatory1 ,april1 #aijf1 p4 #age4 #dci ,houzeau1 ,bibliographie ,gnrale de l',astronomie1 vol4 i41 ,introduction1 p4 #abi4 #ddj ,english ,mechanic1 ,march #be1 #aijd1 p4 #ade4 #dda ,humboldt's ,cosmos1 vol4 iii4 p4 #ahe1 footnote 7,ott's translation74 #ddb ,lalande's ,astronomie1 vol1 i4 p4 #bgg4 #ddc ,this was pointed out by ,flammarion in his work ,les toiles1 page #ecb2 but his identifications do not agree exactly with mine4 #ddd ,see ,proctor's ,map #g1 now x4 #dde ,primitive ,constellations1 vol4 i4 p4 #ajf4 #ddf ,lalande's ,astronomie1 vol4 i4 p4 #bgh4 #ddg ,lalande's ,astronomie1 vol4 iv4 #ddh ,primitive ,constellations1 vol4 i4 p4 #aab4 #ddi ,ibid41 vol4 i4 p4 #aac4 #dej ,lalande's ,astronomie1 vol4 i4 #dea ,w4 ,t4 ,lynn in ,the ,observatory1 vol4 #bb1 p4 #bcf4 #deb ,knowledge1 ,may #a1 #ahhi4 ,sir ,john ,herschel1 however1 gives #cigj ,b4,c4 #dec ,the ,observatory1 ,november #aijg1 p4 #dab4 #ded ,this is not1 however1 invariably the case1 as pointed out by ,mr4 ,denning in ,the ,observatory1 #ahhe1 p4 #cdj4 #dee ,the ,observatory1 vol4 #h 7#ahhe71 pp4 #bdf-g4 #def ,harvard ,college ,observatory ,annals1 vol4 xlviii4 ,no4 #e4 #deg ,popular ,astronomy1 vol4 #ae 7#aijg71 p4 #ebi4 #deh ,cape ,observations1 p4 #gg4 #dei ,monthly ,notices1 ,r4,a4,s41 ,march1 #ahii4 #dfj ,nature1 ,february #ac1 #ahij4 #dfa ,popular ,astronomy1 vol4 #ae 7#aijg71 p4 #ecj4 #dfb ,photographs of ,star-,clusters and ,nebul1 vol4 ii4 p4 #ag4 #dfc ,monthly ,notices1 ,r4,a4,s41 ,may #i1 #ahef4 #dfd ,astrophysical ,journal1 vol4 #be 7#aijg71 p4 #bai4 #dfe ,popular ,astronomy1 vol4 #aa 7#aijc71 p4 #bic4 #dff ,translated by ,w4 ,h4 ,mallock1 ,nature1 ,february #h1 #aijj1 p4 #ceb4 #dfg ,howard ,payn1 ,nature1 ,may #af1 #aija1 p4 #ef4 #dfh ,howard ,payn1 ,nature1 ,may #af1 #aija1 p4 #ef4 #dfi ,contributions from the ,mount ,wilson ,solar ,observatory1 ,no4 #ca4 #dgj ,quoted by ,denning in ,telescopic ,work for ,starlight ,evenings1 p4 #big4 #dga ,astrophysical ,journal1 ,march1 #ahie4 #dgb ,outlines of ,astronomy1 ,tenth ,edition1 p4 #ega4 #dgc ,astrophysical ,journal1 vol4 #ab1 p4 #acf4 #dgd ,de ,placitis4 ,quoted by ,carl ,snyder in ,the ,world ,machine p4 #ced4 #dge ,popular ,astronomy1 vol4 #ad 7#aijf71 p4 #fch4 #dgf ,article on ,the ,greek ,anthology1 ,nineteenth ,century1 ,april1 #aijg1 quoted in ,the ,observatory1 ,may1 #aijg4 #dgg ,popular ,astronomy1 vol4 #ac 7#aije71 p4 #cdf4 #dgh ,bulletin de la ,soc4 ,ast4 de ,france1 ,april1 #aijh4 #dgi ,the ,observatory1 vol4 #aa1 p4 #cge4 #dhj ,grant1 ,history of ,physical ,astronomy1 p4 #cfd4 #dha ,ibid41 p4 #cgg4 #dhb ,ibid41 p4 #cff4 #dhc ,ibid41 p4 #cfg4 #dhd ,grant1 ,history of ,physical ,astronomy1 p4 #cgj4 #dhe ,nature1 ,july #be1 #ahhi4 #dhf ,cosmos1 vol4 iv4 p4 #cha4 #dhg ,cosmos1 vol4 iv4 pp4 #cha-f4 #dhh ,ibid41 vol4 i4 p4 #aba4 #dhi ,the ,observatory1 vol4 #f 7#ahhc71 pp4 #cbg-h4 #dij ,nature1 ,june #be1 #ahgd4 #dia ,popular ,astronomy1 ,may1 #ahie1 ,reflectors or ,refractors4 #dib ,denning1 ,telescopic ,work for ,starlight ,evenings1 p4 #bbe4 #dic ,nature1 ,november #b1 #ahic4 #did ,telescopic ,work1 p4 #bbf4 #die ,copernicus1 vol4 i4 p4 #bbi4 #dif ,grant1 ,history of ,physical ,astronomy1 p4 #dcc4 #dig ,cosmos1 vol4 ii4 p4 #fii4 #dih ,grant1 ,history of ,physical ,astronomy1 p4 #ecf1 footnote4 #dii ,bedford ,catalogue1 p4 #agi4 #ejj ,the ,observatory1 ,july1 #ahia4 #eja ,nature1 ,september #c1 #aijc4 #ejb ,cosmos1 vol4 ii4 p4 #ffi4 #ejc ,the ,world ,machine1 p4 #hj4 #ejd ,ibid41 p4 #hi4 #eje ,grant1 ,history of ,physical ,astronomy1 p4 #ajg4 #ejf ,grant1 ,history of ,physical ,astronomy1 p4 #aac4 #ejg ,nature1 ,august #aa1 #ahih4 #ejh ,ibid41 ,august #ah1 #ahih4 #eji ,ibid41 ,october #bj1 #ahih4 #eaj ,the ,observatory1 vol4 iv4 7#ahha71 p4 #bcd4 #eaa ,w4 ,t4 ,lynn1 ,the ,observatory1 ,july1 #aiji1 p4 #bia4 #eab ,quoted in ,the ,observatory1 ,july1 #aijb1 p4 #bha4 #eac ,astrophysical ,journal1 vol4 #f1 #ahig1 p4 #cjd4 #ead ,celestial ,cycle1 p4 #cfg4 #eae ,the ,observatory1 vol4 #e 7#ahhb71 p4 #bea4 #eaf ,quoted by ,humboldt in ,cosmos1 vol4 ii4 p4 #fif1 footnote4 #eag ,quoted by ,denning in ,telescopic ,work1 p4 #cdg4 #eah ,knowledge1 ,february #bj1 #ahhe1 p4 #adi4 #eai ,humboldt's ,cosmos1 vol4 i4 p4 #abc4 #ebj ,outlines of ,astronomy1 par4 #cai2 edition of #ahge4 #eba ,bulletin de la ,soc4 ,ast4 de ,france1 ,march1 #aijh1 p4 #adf4 #ebb ,an astronomical unit is the sun's mean distance from the earth4 #ebc ,this is on the ,american and ,french system of notation1 but on the ,english system1 #ajff #ajfj #ajf would be a million decillion4 #ebd ,astronomical ,society of the ,pacific1 ,april1 #aiji 7,no4 #abe71 and ,popular ,astronomy1 ,may1 #aiji4 #ebe ,nature1 ,july #bb1 #aiji4 #ebf ,ibid4 #ebg ,the ,observatory1 vol4 #i 7,december1 #ahhf71 p4 #chi4 #ebh ,de ,nat4 ,deorum1 quoted in ,smyth's ,cycle1 p4 #ai4 #ebi ,the ,observatory1 ,may1 #aijg4 #ecj ,more ,worlds than ,ours1 p4 #ag4 #eca ,man's ,place in ,nature4 ,transcriber's ,notes3 ,passages in italics are indicated by italics4 ,superscripted characters are indicated by superscript4 ,subscripted characters are indicated by subscript4 ,the original text includes ,greek characters4 ,for this text version these letters have been replaced with transliterations4 ,foonote #dh appears on page #bh of the text1 but there is no corresponding marker on the page4 ,foonote #ddh appears on page #bie of the text1 but there is no corresponding marker on the page4