Professor A. 0. Leuschner 1868-1953 Gift of Dr.Erida Leuschner Reicheri STAB ATLAS CONTAINING STARS VISIBLE TO THE NAKED EYE AND CLUSTERS, NEBULA AND DOUBLE STARS VISIBLE IN SMALL TELESCOPES TOGETHER WITH VARIABLE STARS, RED STARS, CHARACTERISTIC STAR GROUPS ANCIENT CONSTELLATION FIGURES AND AN EXPLANATORY TEXT BY WINSLOWjJIPTON, A.M. PROFESSOR OF ASTRONOMY IN BROWN UNIVERSITY BOSTON, U.S.A., AND LONDON GINN & COMPANY, PUBLISHERS thenaeum flresa 1896 COPYRIGHT, 1896 BY WIN SLOW UPTON ALL RIGHTS RESERVED REP. GEN. LIB. ACCESS. NO. 7512.0 t ' la GIFT LJ7 P B E FAC E. Tins atlas is designed for teachers and students of Astronomy. Its aim is to supply maps for those who desire to familiarize themselves with the characteristic star groups, and also to include the leading objects of interest in the sky, which those possessing small tele- scopes may wish to examine. As the purpose of the atlas is educational rather than pro- fessional, it has been constructed in a form which it is hoped will be specially adapted to its use, and it contains some features and omits others which would find a place in an atlas for professional use. The maps are on a large scale and are few in number, with liberal overlaps. Con- forming with the plan of systematic study outlined in the text there are six maps, two circumpolar, and four whose areas cover the region between declination N. 40 and S. 40. They are subdivided into four divisions corresponding with the four divisions into which the sky is divided by the equinoctial and solstitial colures. The projection is stereographic, chosen chiefly because of the gradual narrowing of the hour circles on the equatorial maps as the declination increases, and the better correspondence of the equatorial and polar maps at their marginal overlaps. The" six skeleton maps are -reduced from the larger ones, and are designed to give the characteristic stellar figures of each constellation area with greater prominence than they appear on the larger maps. This is secured by omitting the fainter stars and the historical figures, and by connecting the stars by guiding lines. The educational purpose of the atlas has caused the retention of the outlines of the historical figures, which are usually omitted on professional atlases. They are given in merest outline and for the older constellations of the northern sky only, because of frequent allusions to them in literature. Similar figures were supplied by those astronomers of the eighteenth and nineteenth centuries who completed the system of constellations in the southern hemisphere, but they were added when the use of the figures was becoming obso- lete ; they are of decidedly inferior character in their subjects, since they include such mechanical objects as air-pump, clock, telescope, chemical furnace ; and they have no place in literature. For these reasons they are not reproduced. The purpose of the atlas required its preparation according to the best astronomical authorities of to-day. The prevailing usage of modern astronomers has been the criterion adopted ; where usage varies, a decision was necessary, and it has been made with great care. The only place where any serious difficulty has arisen has been the proper location of the boundaries between the constellation areas, in which there is no general agreement. The epoch of the atlas is 1900, and the star places have all been reduced from various catalogues to that epoch before charting. The stars charted are those down to the 6.0 magnitude, thus including those readily visible to the naked eye. A large number of faint stars rarely visible without a iv PREFACE. telescope, and which crowd an atlas, were thus omitted. The authority for the magnitudes is Harvard Photometry, and its extension to the south pole, vols. xiv, xxiv, and xxxiv of the Annals of the Astronomical Observatory of Harvard College. Argelander's Uranometria Nova is the basis of the boundaries between the constella- tion areas, and also of the outlines of the historical figures. Behrmann's extension of the constellations to the southern pole on Argelander's plan has been adopted on the large maps, and Gould's revision, which supersedes Argelander's south of 10 N. declination, for the smaller maps. The designations of the stars follow Argelander, Behrmann, Heis, and Gould. The added letters of Gould are used except where his revision of the areas places a star in another constellation. The Milky Way is drawn only approximately, based upon the drawings of Heis and Gould. The meanings of the Arabic names of stars are taken from Higgins' Arabic Names of Stars. The clusters and nebulae charted were selected from Dreyer's New Catalogue, the variables from Chandler's Second Catalogue, the colored stars from the list in Chambers' Astronomy and from the notes in Gould's Uranometria Argentina and other catalogues. The double stars include those within the limits adopted which are catalogued in Webb's Celestial Objects, and those mentioned by Gould and others. The authority for the posi- tions and notes in the table is Crossley, Gledhill, and Wilson's Handbook of Double Stars, and more recent publications of^ various observers. t The work has been done independently of other publications, but comparisons have been made with other atlases and star lists in order to secure freedom from error as far as possible. Acknowledgment for advice is due and is gratefully made to several astronomers and educators who have been consulted, especially to Prof. E. C. Pickering, Prof. C. A. Young, and Mr. D. W. Hoyt. The reproduction of the outlines of the historical figures is due to the skill of Mr. N. M. Isham of Brown University and the engravers Messrs. Bradley and Poates. WINSLOW UPTON. BROWN UNIVERSITY, PROVIDENCE, R. I., June, 1896. EXPLANATORY TEXT. THE CONSTELLATIONS. THE division of the sky into constellations is the oldest part of the science of Astronomy. It was begun in prehistoric times by Chaldean and Egyptian astronomers, and was further developed by the Greeks. The Arabian scholars of the Middle Ages received the system from the Greeks and handed it down, with a few modifications, to European astronomers. Many additions and alterations were made by astronomers after the sixteenth century. To-day the system is still used, but only for purposes of notation, and it has ceased to be of much importance in the strict science of Astronomy. The primitive astronomers adopted the pictorial plan of distinguishing the stars. ived long ions. ; our ERRATA. iefly tury PAGE 27. Third sentence from foot should read: Cassiopeia is above the pole towards the right, Ursa Major low in the sky below the pole. ' MAPS I AND VI. The names of the months should be changed from January to July, from February to August, and so on. was i the Hist the 3 US, but in Ptolemy's and in subsequent star catalogues the position of each star is given in two ways : (1) by its place in the constellation figure, and (2) by the system of longitude and latitude which the Greeks had adopted. The latter system enables the modern astronomer to identify the stars, and the former to reproduce the outline of the figure with partial success, depending upon the character of the figure and upon the number of the stars in the group. Where the constellation has but few stars, as Canis Minor, which has but two stars in Ptolemy's catalogue, the reproduction of the traditional figure is very uncertain. In the sixteenth century, the German astronomer Heinfogel secured the assistance of the artist Albrecht Diirer in reproducing the classic figures, and his highly embellished drawings formed the basis of the figures given on globes and atlases until the nineteenth century. 2 Present atlases either omit them entirely, or give them in merest outline because of their historical interest and the frequent allusions to them in literature. They have ceased to have any use in modern Astronomy. The first change in the system of constellations described by Ptolemy was made by transferring the name of the constellation from the space included within the outlines of 1 Baily's edition iu Memoirs R. A. S., vol. xiii. * Annales Astronomiques, I, 1878. iv PREFACE. telescope, and which crowd an atlas, were thus omitted. The authority for the magnitudes is Harvard Photometry, and its extension to the south pole, vols. xiv, xxiv, and xxxiv of the Annals of the Astronomical Observatory of Harvard College. Argelander's Uranometria Nova is the basis of the boundaries between the constella- tion areas, and also of the outlines of the historical figures. Behrmann's extension of the constellations to the southern pole on Argelander's plan has been adopted on the large maps, and Gould's revision, which supersedes Argelander's south of 10 N. declination, for the smaller maps. The designations of the stars follow Argelander, Behrmann, Heis, and Gould. The added letters of Gould are used except where his revision of the areas places a star in another constellation. The Milky Way is drawn only approximately, based upon the drawings of Heis and Gould. Th. of Stan Th. variable Astrono The doi Celestia tions ai and me Th been m as poss Ac educate and Mr the skL. u*. +.^. ^.. - . Poates. W1NSLOW UPTON. BROWN UNIVERSITY, PROVIDENCE, R. I., June, 1896. EXPLANATORY TEXT. THE CONSTELLATIONS. THE division of the sky into constellations is the oldest part of the science of Astronomy. It was begun in prehistoric times by Chaldean and Egyptian astronomers, and was further developed by the Greeks. The Arabian scholars of the Middle Ages received the system from the Greeks and handed it down, with a few modifications, to European astronomers. Many additions and alterations were made by astronomers after the sixteenth century. To-day the system is still used, but only for purposes of notation, and it has ceased to be of much importance in the strict science of Astronomy. The primitive astronomers adopted the pictorial plan of distinguishing the stars. They selected from the heavens prominent groups of stars, gave to them names derived from natural objects or from their mythology, and imagined figures to be drawn among the stars to represent the objects. Thus was formed the ancient system of constellations. Many of them are mentioned by early writers such as Homer, Hesiod, and Aratus, but our knowledge of the definite location of the groups to which they allude is derived chiefly from the star catalogue of the Greek astronomer Ptolemy, who lived in the second century of the Christian era. This star catalogue 1 contains 1028 stars and is made up of the brighter stars visible in northern latitudes. It groups the stars into forty-eight constel- lations, which include 926 of the whole number ; the others are mentioned as unclassified, and are given as additional to the constellations near which they lie. It is probable that the early astronomers did not intend to map out the whole sky into constellations, but simply to select the prominent groups and give them names for convenience in their study. Astrology furnished the motive for the classification, and the study of the star groups was directed to the determination, if possible, of the influence which the groups had upon the earth and its inhabitants. Some prominent stars, as Arcturus, were in the unclassified list and not in any constellation. The individual stars were named from their positions in the figures which the astronomers drew among the stars. The figures themselves have not come down to us, but in Ptolemy's and in subsequent star catalogues the position of each star is given in two ways : (1) by its place in the constellation figure, and (2) by the system of longitude and latitude which the Greeks had adopted. The latter system enables the modern astronomer to identify the stars, and the former to reproduce the outline of the figure with partial success, depending upon the character of the figure and upon the number of the stars in the group. Where the constellation has but few stars, as Canis Minor, which has but two stars in Ptolemy's catalogue, the reproduction of the traditional figure is very uncertain. In the sixteenth century, the German astronomer Heinfogel secured the assistance of the artist Albrecht Diirer in reproducing the classic figures, and his highly embellished drawings formed the basis of the figures given on globes and atlases until the nineteenth century. 2 Present atlases either omit them entirely, or give them in merest outline because of their historical interest and the frequent allusions to them in literature. They have ceased to have any use in modern Astronomy. The first change in the system of constellations described by Ptolemy was made by transferring the name of the constellation from the space included within the outlines of 1 Baily's editiou in Memoirs 11. A. S., vol. xiii. Annales Astronomiques, I, 1878. 2 EXPLANATORY TEXT. the figure to a larger space in the sky, within which the figure represented by the name was included. Then new constellations were added in the spaces between the original groups, with the design of covering the whole sky with constellations. The new constel- lations were added chiefly by astronomers between the sixteenth and nineteenth centuries, who worked independently of each other. As a result there was no agreement either in the new constellations or in the drawing of the boundaries between adjacent areas. To-day there is still disagreement on both these points ; professional astronomers use different designations for different parts of the sky, and star atlases are not in harmony with each other, especially for the constellations in the southern hemisphere. The ancient system of the constellations, with its subsequent additions, survives in modern Astronomy simply as a means of subdividing the heavens and of giving names to the areas thus set apart. As the system has been one of growth, without any distinct plan except the separation of prominent groups of stars, the resulting areas are of various sizes and shapes. In a few cases the constellation figures crossed each other ; the best example of this is the constellation Serpens, which crossed Ophiuchus, the figure repre- senting the serpent-carrier holding the serpent in his hands. In the modern atlas the area called Serpens is divided into two portions, the western part, marked Caput, and the eastern, Cauda, to correspond with the positions of the head and the tail of the serpent, and the area named Ophiuchus extends between them. In some cases, moreover, the same star was in more than one figure. Thus the northeastern star in the " Square of Pegasus " is given in Bayer's Atlas both as 8 Pegasi and also as a Andromedce. Not only are the constellation areas of various sizes, but there is no law by which the boundaries between them can be definitely marked. The aim of the compilers of atlases has been to preserve the relation of the areas to the ancient figures as far as possible. The lack of concerted action has necessarily resulted in variety of treatment, and the matter of the position of the boundaries is of such minor importance in modern Astronomy that little interest has been shown in the various schemes proposed for rectifying the boundaries. A radical change was suggested by Sir John Herschel in 1841 J ; he advocated a complete rearrangement of the areas, especially of those in the southern sky, and proposed that each area be made a quadrilateral bounded by arcs of hour circles and parallels of declinations. This scheme did not meet with favor, but it was revived in a modified form by Dr. Gould in 1879, 2 for the southern constellations, and their boundaries were drawn by arcs of hour circles or of other great circles and parallels of declination. The new system of boundaries was made to depart from the former system at the parallel 10 north declination, and all the areas south of this region were bounded by definite arcs on the above plan instead of by the irregular lines formerly represented. This system is coming into extensive use, as it is employed for the designation of variable stars, the only growing branch of modern Astronomy in which new star names are needed. The old areas are, however, still retained by some astronomers in preference to the revised areas, and stars previously named on the old plan, which under the new plan would require renaming, are usually mentioned under their earlier names. In this star atlas the constellation areas are named and their boundaries are defined according to modern usage ; where usage varies it has been necessary to adopt one in preference to others. The Uranometry of Argelander, published in 1840, extending from the north pole to 20 or 30 south declination, has been used within these limits ; and its extension to the south pole, executed on the same plan by Behrmann in 1874, has been used for the remainder of the sky. On the smaller maps containing the characteristic star 1 Memoirs R. A. S., vol. xii. 2 Uranometria Argentina. THE CONSTELLATIONS. groups of the constellation areas, the boundaries adopted have been those of Argelander from the north pole to 10 north declination, and the reformed boundaries of Gould from that parallel southward. NAMES OF THE CONSTELLATIONS. The following table contains the names of the constellations included in this atlas. They are given in their Latin form, which is almost universally used, with accents to assist in their pronunciation. The genitive case of the name is also appended, as it is used in the designations of the brighter stars in each constellation. Other columns contain the meaning of each word, where it is not a proper name, and the map or maps upon which it is found. The name of the proposer of the constellation is appended. The letter P in this column indicates that the constellation was in Ptolemy's catalogue, and therefore belongs to the list of constellations used by the ancient astronomers. The twelve constellations ascribed to Bayer were introduced into his atlas from earlier observations. The origin of Crux and Cohimba is not definitely known, and some of Hevelius' constel- lations were in use before his time. The constellation Argo is usually subdivided into four parts, named Carina, Malus, Puppls, and Vela. The genitive Argus is often used with stars designated by Greek letters, but the modern tendency is to use the genitive of the name of the subdivision in which each star is situated. TABLE I. THE CONSTELLATIONS. No. NAME. GENITIVE. MEANING. MAP. PROPOSER. 1 Androm'-eda Androm'-edse I, II P 2 Ant'-lia Ant'-lise Air pump III Lacaille 3 A'-pus Ap'-odis Bird of Paradise VI Bayer 4 Aqua'-rius Aqua'-rii Water carrier V P 5 A'-quila A'-quilse Eagle V P 6 A'-ra A'-rae Altar VI P - Ar'-go (Navls) Ar'-gus Ship Argo III, VI P 7 A'-ries Ari'-etis Ram II P 8 Auri'-ga Auri'-gae Charioteer I, II, III P 9 Boo'-tes Boo'-tis Bear keeper I, IV P 10 Cae'-lum Cae'-li Sculptor's chisel II, VI Lacaille 11 Camelopar'-dalis Camelopar'-dalis Giraffe I Hevelius 12 Can'-cer Can'-cri Crab III P 13 Ca'-nes Venat'-ici Ca'-numVenatico'-rum Hunting dogs I, IV Hevelius 14 Ca'-nis Ma'-jor Ca'-nis Majo'-ris Greater dog III P 15 Ca'-nis Mi'-nor Ca'-nis Mino'-ris Lesser dog III P 16 Capricor'-nus Capricor'-ni Goat V P 17 Cari'-na Cari'-nse Keel(of ship Argo) VI -r 18 Cassiope-ia Cassiope'-ise I P 19 Centau'-rus Centau'-ri Centaur IV, VI P 20 Ce'-pheus Ce'-phei I P 21 Ce'-tus Ce'-ti Whale II P 22 Chamse'-leon Chamaeleon'-tis Chamaeleon VI Bayer 23 Cir'-cinus Cir'-cini Pair of compasses VI Lacaille 24 Colum'-ba Colum'-bae Dove II, VI 25 Co'-ma Bereni'-ces Co'-mse Bereni'-ces Berenice's hair IV Tycho Brahe 26 Coro'-na Austra'-lis Coro'-nee Austra'-lis Southern crown V, VI P 27 Coro'-na Borea'-lis Coro'-nse Borea'-lis Northern crown IV P 28 Cor'-vus Cor'-vi Crow IV P 29 Cra'-ter C rate -r is Cup III P 30 Crux Cru'-cis Cross VI 31 Cyg'-nus Cyg'-ni Swan I, V P 32 Delphi'-nus Delplii'-ni Dolphin V P EXPLANATORY TEXT. No. NAME. GENITIVE. MEANING. MAP. PROPOSER. 33 Dora'-do Dora'-dus Sword fish VI Bayer 34 Dra'-co Draco '-iris Dragon I P 35 Equu'-leus Equu'-lei Little horse V P 36 Erid'-anus Erid'-ani River Po II, VI P 37 For'-nax (chemica) Forna'-cis Furnace II Lacaille 38 Gem'-ini Gemino'-rum Twins III P 39 Grus Gru'-is Crane V, VI Bayer 40 Her'-cules Her'-culis I, IV P 41 Horolo'-gium Horolo'-gii Clock II, VI Lacaille 42 Hy'-dra Hy'-dree Snake III, IV P 43 Hy'-drus Hy'-dri Watersnake VI Bayer 44 In'-dus In'-di Indian VI Bayer 45 Lacer'-ta Lacer'-tae Lizard i,v Hevelius 46 Le'-o Leo'-nis Lion III P 47 Le'-o Mi'-nor Leo'-nis Mino'-ris Lesser lion III Hevelius 48 Le'-pus Lep'-oris Hare II P 49 Li'-bra Li'-brae Balance IV P 50 Lu'-pus Lu'-pi Wolf IV, VI P 51 Lynx Lyn'-cis Lynx I, III Hevelius 52 Ly'-ra Ly'rse Harp i,v P 53 Ma'-lus Ma'-li Mast(ofshipArgo) III 54 Men'-sa(Mons Mensse) Men'-sae Table (mountain) VI Lacaille 55 Microsco'-pium Microsco'-pii Microscope V Lacaille 56 Monoc'-eros Monocero'-tis Unicorn III Hevelius 57 Mus'-ca Mus'-cse Fly VI Bayer 58 Nor'-ma Nor'-mae Rule IV, VI Lacaille 59 Oc'-tans Octan'-tis Octant VI Lacaille 60 Ophiu'-chus Ophiu'-chi Serpent carrier IV, V P 61 Ori'-on Orio'-nis II, III P 62 Pa'-vo Pavo'-nis Peacock VI Bayer 63 Peg'-asus Peg'-asi Winged horse V P 64 Per'-seus Per'-sei I, II P 65 Phoe'-nix Phceni'-cis Phosnix II, VI Bayer 66 Pic-tor (Equuleus Pic- Picto'-ris Painter's easel VI Lacaille toris) 67 Pis'-ces Pis'-cium Fishes II, V P 68 Pis'-cis Austra'-lis Pis'-cis Austra'-lis Southern fish V P 69 Pup '-pis Pup '-pis Stern (of ship Argo) III, VI 70 Retic'-ulum Retic'-uli Net VI Lacaille 71 Sagit'-ta Sagit-tae Arrow V P 72 Sagitta'-rius Sagitta'-rii Archer V, VI P 73 Scor'-pius Scor'-pii Scorpion IV, VI P 74 Sculp'-tor (Apparatus Sculpto'-ris Sculptor's appara- 1I,V,VI Lacaille Sculptoris) tus 75 Scu'-tum (Sobiesii) Scu'-ti Shield of Sobieski V Hevelius 76 Ser'-pens Serpen'-tis Serpent IV, V P 77 Sex'-tans Sextan '-tis Sextant III Hevelius 78 Tau'-rus Tau'-ri Bull II P 79 Telesco'-pium Telesco'-pii Telescope VI Lacaille 80 Trian'-gulum Trian'-guli Triangle II P 81 Trian'-gulumAustra'-le Trian'-guli Austra'-lis Southern triangle VI Bayer 82 Tuca'-na Tuca'-nae American goose VI Bayer 83 Ur'-sa Ma'-jor Ursae Majo'-ris Greater bear I, III P 84 Ur'-sa Mi'-nor Ursae Mino'-ris Lesser bear I P 85 Ve'-la Velo'-rum Sails (of ship Argo) III, VI 86 Vir'-go Vir'-ginis Virgin IV P 87 Vo'-lans (Piscis volans) Volan'-tis Flying fish VI Bayer 88 Vulpec'-ula (cum an- Vulpec'-ulae Fox with goose V Hevelius sere) DESIGNATIONS OF STARS. 5 The above list of constellations includes all which are generally accepted at the present time. The total number is eighty-five if Argo is considered as one constellation, or eighty-eight if each of its subdivisions is reckoned as a separate constellation. There are many other constellations which have been proposed by eminent astronomers and used to a limited extent. 1 Thus Bode added nine constellations, one of which, Machina Electrica, was inserted by Argelander in his supplementary map of the southern heavens. Lacaille substituted for Malm the name Pyxis (genitive Pyx-idos] mariner's compass, and this is extensively used to-day. The constellation Antinous, ascribed to Tycho Brahe, is included in Aquila; Taurus Poniatowskii, ascribed to Poczobut, is included in Ophiuchus and Serpens. The constellation Libra, which is the only one of the twelve zodiacal groups not bearing the name of an animal as the derivation of the word zodiac implies, is in Ptolemy's catalogue called Clatvs (of the Scorpion). Scutum is sometimes called by its Greek equivalent Clypeus. DESIGNATIONS OP STARS. Individual stars have been designated by astronomers in several different ways : 1. By their position in the constellation figure. This method is now entirely obsolete. 2. By individual names. The names have come down to us chiefly from classical and mediaeval times, and are either of Latin form or in a corrupted form of the Arabic desig- nation of the star in its constellation figure. Very few of the names are now used. The method is nearly obsolete, surviving in only a few of the brightest stars. 3. By Greek or Roman letters, followed by the name of the constellation in the genitive case of its Latin form. This method was introduced by Bayer early in the seventeenth century, who lettered the leading stars in each constellation of the northern heavens, using the Greek alphabet, and if the number of stars in the constellation exceeded the number of Greek letters, using Roman letters. The stars were lettered in the order of their bright- ness as far as the several magnitudes were concerned, but no attempt seems to have been made to distinguish between the stars of any given magnitude. Later astronomers have adopted the same system in constellations not in Bayer's list. Nearly all of the stars readily visible to the naked eye are designated by letters on this plan, and astronomers prefer this system to any of the others. 4. By Arabic numbers, followed by the name of the constellation in the genitive case of its Latin form. This method was introduced by Flamsteed in the seventeenth century, whose numbers follow the order of the stars in right ascension. Other astronomers used the same plan. This method is used by astronomers for stars not already lettered on Bayer's plan. Where both letters and numbers have been given, the letters are preferred. 5. By the current number in any well-known modern star catalogue. This method is used when the star has neither letter nor number. 6. By the position of the star in the sky, the system corresponding to longitude and latitude on the earth. On the celestial sphere, right ascension and declination are the terms employed. This method is used for uncatalogued stars. The brightest stars have designations in all six of the above ways. Thus the bright star which is near the northern celestial pole was designated (1) the star at the end of the tail of the lesser bear, (2) Gjedi, Polaris, Cynosura, Alruccabah, (3) a Ursce Minoris, (4) 1 Ursce Minoris. It might also be referred to under (5) as B. A. C. 360, the current number 1 See Chambers' Astronomy, vol. iii, chap, vii, ed. 1890, and Burritt's Geography of the Heavens. EXPLANATORY TEXT. in the British Association Catalogue (or by a similar designation in any other catalogue in which it occurs), and under (6) as in right ascension 1 h. 23 min., declination + 88 46'. Of these names, a Ursce Minoris is preferred, but Polaris is still in frequent use ; all the other designations are obsolete. The majority of stars readily visible to the naked eye are therefore usually designated by letter and name of constellation area ; a large number, especially of the fainter ones, are called by a number with the name of the constellation area ; a few have individual names. The faintest stars visible without a telescope, and all requiring its aid, are referred to by their numbers in star catalogues, or by their right ascensions and declinations. In this atlas, following present usage, the individual stars are designated by a letter or by a number, if such letter or number is in use. The individual names of stars of the first magnitude, and of a few others which are extensively used, are also given upon the maps. In referring to the stars, the letter or number should be used with the genitive of the name of the constellation given in Table I, as a Herculis, 61 Cygni. The Greek alphabet is here given. GREEK ALPHABET. a alpha V nu P beta 1 xi V gamma o om'-icron 5 delta IT Pi eps'-ilon P rho zeta Centauri, visible to naked eye 5272 13 38 28 53 IV very bright, very large, vast number of stars STAR CLUSTERS AND NEBULA. 11 No. N. G. C. RIGHT ASCENSION. DECLINATION. MAP. DESCRIPTION. 5822 14 h. 58 m. -53 57' VI very large, many stars 5904 15 13 2 27 IV very bright, large, many stars 5986 15 40 -37 27 IV very bright, large 6067 16 5 53 57 VI very bright, very large, very many stars 6087 16 11 -57 39 VI bright, large, stars 7th to 10th magnitude 6093 16 11 -22 44 IV very bright, large, globular, easily resolved 6169 16 27 -43 50 IV, VI about /j. Normce 6171 16 27 -12 50 IV large, very many stars, easily resolved 6205 16 38 36 39 IV very bright, vast number of faint stars 6218 16 42 1 46 IV very bright, very large, easily resolved 6227 16 45 -41 3 IV, VI exceedingly large, very rich in stars 6254 16 52 3 57 IV bright, very large, easily resolved 6259 16 54 -44 31 IV, VI bright, very large, very many stars 6266 16 55 -29 58 IV very bright, large, globular, easily resolved 6333 17 13 -18 25 IV bright, large, globular, easily resolved 6341 17 14 43 15 I, IV very bright, very large, globular, easily resolved 6402 17 32 - 3 11 IV, V bright, very large, very many stars, globular 6444 17 44 -34 50 IV, V very large, very many stars 6475 17 48 -34 47 IV, V very bright, many stars 6494 17 51 -19 IV, V bright, very large, many stars 6523 17 57 -24 23 IV, V very bright, very large 6568 18 7 -21 37 IV, V very large, stars of 10th magnitude 6603 18 13 -18 27 IV, V very many stars, visible to naked eye 6611 18 13 -13 49 IV, V many stars 6626 IS 18 -24 55 IV, V very bright, large, easily resolved 6633 18 23 6 29 IV, V many bright stars, visible to naked eye 6656 18 30 -23 59 IV, V very bright, very large, very many stars, globular 6705 18 46 6 23 V very bright, large 6752 19 2 -60 8 VI bright, very large, easily resolved 6838 19 49 18 31 V very large, very many stars 6866 20 43 43 I, V large, very many stars 6885 20 8 26 10 V very bright, very large, stars 6th to llth magnitude 6940 20 30 27 58 V very bright, very large, very many stars 7078 21 25 11 44 V very bright, very large, easily resolved 7089 21 28 - 1 16 V bright, very large, easily resolved 7092 21 29 48 I very large, stars 7th to 10th magnitude 7099 21 35 -23 38 V bright, large, globular 7243 22 11 49 23 I large, bright stars 7654 23 20 61 3 I large, many stars 7789 23 52 56 10 I very large, very many stars TABLE V. NEBULAE. No. N. G. C. RIGHT ASCENSION. DECLINATION. MAP. DESCRIPTION. 55 Oh. 10m- -39 46' II, V very bright, very large, very much elongated 221 37 40 19 I, II exceedingly bright, large, round 224 37 40 43 I, II exceedingly bright, large and elongated 253 43 -25 51 II, V exceedingly bright, large and elongated 598 1 28 30 9 II very bright, very large, round 613 1 29 -29 55. II very bright, very large, very much elongated 650 1 36 51 4 I very bright } 651 1 36 51 5 I very bright ) 936 2 23 - 1 35 II very bright, very large 1023 2 34 38 38 II very bright, very large and elongated 1365 3 30 -36 32 II very bright, very large and elongated 1535 4 10 -13 II very bright, small, planetary 1559 4 16 -63 2 VI very bright, very large and elongated 12 EXPLANATORY TEXT. No. N. G. C. EIGHT ASCENSION. DECLINATION. MAP. DESCRIPTION. 1763 4 h- 57 m. -66 34' VI very bright, very large 1952 5 28 21 57 11, 111 very bright, very large and elongated 1976 5 30 - 5 27 II, III great nebula about 6 Orionis 1977 5 30 - 4 54 II, III about c Orionis 1978 5 28 -66 18 VI very bright, very large, oval 1982 5 31 - 5 20 II, III very bright, very large 1990 5 31 1 16 II, III very large, about c Orionis 2024 5 37 - 1 54 II, III bright, very large 2070 5 39 -69 9 VI very bright, very large, looped 2392 7 23 21 7 III bright, small, round 2403 7 27 65 49 I quite bright, very large and elongated 2683 8 46 33 48 III very bright, very large and elongated 2841 9 15 51 24 I very bright, large and much elongated 2867 9 19 -57 53 VI very small, planetary 3031 9 47 69 32 I exceedingly bright and large 3115 10 - 7 14 III very bright, large and much elongated 3132 10 , 3 -39 57 III very bright, very large, oval 3199 10 13 -57 28 VI very bright, very large 3242 10 20 -18 8 III very bright, blue tint, planetary 3372 10 41 -59 9 VI diffused and branching about rj Carince (Argus) 3379 10 43 13 6 III very bright, quite large 3587 11 9 55 34 I very bright, very large, planetary 3623 11 14 13 38 III bright, very large 3918 11 45 -56 37 VI small, round, blue tint, planetary 4254 12 14 14 59 III, IV bright, large, round, three-branched spiral 4258 12 14 47 52 I very bright, very large and elongated 4382 12 20 18 45 III, IV very bright, quite large and round 4565 12 31 26 32 III, IV bright, very large and elongated 4594 12 35 -11 4 III, IV very bright, very large and elongated 4595 12 35 28 31 III, IV very bright, very large and elongated 4631 12 37 33 16 III, IV very bright, very large and elongated 4736 12 46 41 40 I, IV very bright, large 4826 12 52 22 43 IV very bright, very large and elongated 5128 13 20 -42 30 IV, VI very bright, very large and elongated 5194 13 26 47 42 I great spiral nebula 5236 13 31 -29 21 IV very bright, very large, three-branched spiral 5367 13 52 39 30 IV very bright, very large and elongated 6210 16 40 23 59 IV very bright, very small, planetary 6326 17 13 -51 38 VI bright, small, planetary 6369 17 23 -23 41 IV, V bright, small, annular 6514 17 56 23 2 IV, V very bright, very large, trifid 6523 17 57 -24 23 IV, V very bright, very large, in cluster 6543 17 58 66 38 I very bright, small, planetary 6572 18 7 6 50 IV, V very bright, small, planetary 6618 18 15 -16 13 IV, V bright, very large, two-hooked 6720 18 50 32 54 IV, V bright, quite large, annular 6853 19 55 22 27 V very bright, very large, double condensation 6905 20 18 19 47 V bright, small, planetary 6960 20 42 30 21 V quite bright, large, around K Cygni 7009 20 59 -11 46 V very bright, small, elliptical 7662 23 21 41 59 I very bright, small, blue tint, planetary NOTES TO TABLES IV AND V. 221. Companion nebula to the Great Nebula in Andromeda. 224. THE GREAT NEBULA IN ANDROMEDA. It is plainly visible to the naked eye, and is the brightest nebula in the heavens. It has a nucleus and dark streaks which in the photographs are curved as if indicating a spiral structure. THE COLORS OF STAliS. 13 869, 884. These two clusters are visible to the naked eye and are designated h and % Persei, respectively. They are magnificent clusters when viewed with a low-power eyepiece. 1952. THE CRAB NEBULA. It is so named from its appearance in Lord Rosse's reflector. 1976. THE GKEAT NEBULA IN ORION. It surrounds Orionis, which is visible to the naked eye as a single star, and in the telescope forms the group of four principal stars and two fainter ones known as the trapezium. The rebula is the largest in the sky and has a great rift in it, and also several extensions of irregular shape. A large number of faint stars are involved in the nebula. 3372. THE NEBULA AROUND -q CARLISLE (ARGUS). This is in a region containing many stars forming an immense cluster involved in nebulous matter. The star 77 Carince, now of about seventh magnitude, was of extraordinary brilliancy in 1843, exceeded only by Sirius ; it fluctuated very much in brightness between 1800 and 1870. 5139. This cluster, visible to the naked eye and known as u> Centauri, is probably the most magnificent in the sky. It contains several thousand stars. 5194. THE GREAT SPIRAL NEBULA. It was so named by Lord Rosse. It is not very con- spicuous in small telescopes, and its structure is distinguishable only in the largest instruments. 6205. This cluster, often called the GREAT CLUSTER IN HERCULES, is perhaps the most magnificent visible to northern observers. It is very densely packed with faint stars. 6514. THE TIUFID NEBULA. It contains several dark rifts, and there is evidence that the nebula lias moved, from the change in position of a star with regard to one of these rifts. 6618. THE HORSESHOE NEBULA. It shows this shape only in large instruments. 6720. THE RING NEBULA IN LYRA. This is the brightest of the circular nebulae whose condensation is around the circumference of the nebula instead of at its centre. 6853. THE DUMBBELL NEBULA. It was so called by Lord Rosse from its double condensation. 7009. Sometimes called the Saturn Nebula, from a ring seen within the nebula in large telescopes. In addition to the clusters of Table IV, the whole Milky Way abounds in regions in which the stars are closely compressed, and a telescope with a low-power eyepiece will reveal many bril- liant star groups. The naked-eye cluster, the Pleiades, also abounds in fainter stars, more than a thousand having been counted and the photographs showing a nebulous background in addition. THE COLORS OF STARS. The stars vary in color from red to blue, according to their physical condition. The red stars are in many cases variable. The estimates of color by different observers are often very conflicting, as they depend not only upon the true color of the star, but also upon the condition of the atmosphere, the color imperfection of the telescope used, and the sensitiveness of the observer's eye to differences of tint. Moreover as the star appears as a mere point of light, the color does not seem as pronounced as the word used to express it suggests. In this atlas, stars of a red color are indicated by the letter R placed as a subscript to the letter or number designating the star. If the star has no letter or number the R is placed in parenthesis. Other colors than red are not indicated. The following table con- tains the stars which are charted as red, in which the color is especially marked, and also a few of other colors which are noteworthy. 14 EXPLANATORY TEXT. TABLE VI. PROMINENT COLORED STARS. NAME. RIGHT ASCENSION. DECLINATION. MAGNI- TUDE. MAP. COLOR. 8 Andromedse h- 34 m. 30 19' 3 II, V Orange R Sculptoris 1 22 -33 4 var. II Red a Eridani 1 34 -57 44 1 VI Red y Andromedae 1 58 41 51 2 I, II Orange o Ceti 2 14 3 26 var. II Red at maximum R Trianguli 2 31 33 50 var. II Red a Ceti 2 57 3 42 3 II Orange - Eridani 4 30 - 9 10 6 II Red a Tauri 4 30 16 19 1 II Red R Doradus 4 36 -62 16 var. VI Red 5 Orionis 4 48 2 21 6 II Orange R Leporis 4 55 -14 57 var. II Very red Aurigae 4 56 40 56 4 1,11 Orange a Orionis 5 47 7 23 var. II, III Red 5 Lyncis 6 18 58 29 6 I Very red Aurigae 6 30 38 31 6 II, III Very red /n Canis Majoris 6 51 -13 54 5 III Very red L 2 Puppis 7 10 44 29 var. III, VI Very red Puppis 7 29 -14 18 5 III Very red Mali 9 4 25 27 5 III Red R Leonis 9 42 11 54 var. III Red U Hydras 10 33 -12 52 var. III Red /JL Argus 10 42 -48 54 3 VI Red Centauri 12 37 48 16 5 VI Very red R Hydrae 13 22 -22 32 var. IV Red R Centauri 14 9 59 27 var. VI Red a Bootis 14 11 19 42 IV Yellow Trianguli Australis 15 5 -69 42 5 VI Red /3 Librae 15 12 9 1 3 IV Pale green 1 Lupi 15 16 35 54 3 IV Very red X Herculis 16 47 31 var. I Red Scorpii 16 2 -26 3 5 IV Red a Scorpii 16 23 -26 13 1 IV Very red a 1 Herculis 17 10 14 31 3 IV Orange y Draconis 17 54 51 30 2 I Orange 4 Vulpeculaa 19 21 19 37 5 V Orange R Cygni 19 34 49 58 var. I Red X Cygni 19 47 32 40 ' var. V Red T Cephei 21 8 68 5 var. I Red /n Cephei 21 40 58 19 var. I Red 8 Andromedae 23 13 48 28 5 I Red 19 Piscium 23 41 2 56 5 II, V Red R Cassiopeiae 23 53 50 50 var. I Red 30 Piscium 23 57 - 6 34 5 II, V Red VARIABLE STARS. 15 VARIABLE STARS. In this atlas are included variable stars whose brightness at their maximum equals the sixth magnitude, and also temporary stars which at their brightest were visible to the naked eye but now require a telescope or are wholly invisible. They are indicated by the letter F placed as a subscript to the letter or number designating the star ; if the star has no letter or number the letter V is placed in parenthesis. Variable stars, if not already lettered, are designated by the later letters of the alphabet, beginning with R, followed by the Latin genitive of the constellation. They are lettered in the order of their discovery, and after Z is reached the letters 'are repeated in pairs, RR, RS, etc. The star symbol used on the maps corresponds with the maximum brightness, except in the case of temporary stars now invisible to the naked eye. The following table con- tains those charted, with notes regarding the changes in brightness which they experience. The list is made from Chandler's Second Catalogue of Variable Stars. 1 The numbers in the first column are those of that catalogue. Stars of the Algol-type are those which are usually at their maximum brightness, but which periodically decrease to a minimum and return again to the maximum. The variability of the light of stars is of especial interest, because it must be accounted for in any theory of the physical state of the stars. Slow changes in the amount of light given out are to be expected, but periodical changes require special explanation. The greatest interest attaches to stars of the Algol-iype, which are most naturally accounted for by the periodic passing between us and the star of an eclipsing body. That such a body exists in the case of Algol has been proved by the periodic displacement of the lines in the spectrum of the star, so that the star and its companion really form a binary, the two revolving around their common centre of gravity. Another class of variables exhibits the light change in a manner precisely the reverse of that of the Algol stars, the star remaining at its minimum brightness the greater part of the time and periodically increasing to a maximum. The periods are not always the same, nor is the brightness at the successive maxima uniform, so that the explanation of this type of variability is not simple and is at present quite conjectural. Another class of variables shows continuous changes in the light, now increasing and now decreasing, the star not remaining at all at any definite degree of brightness. The successive maxima and minima and the rates of change are often variable also, so that the phenomenon is very complicated. Other stars occasionally fluctuate in brightness, but not in any distinct period which can be determined. Another class of variables includes the New or Temporary Stars, improperly so called because they are not new creations, and it is only the great increase of light which is temporary. In every case the light increases rapidly to a maximum, and decreases more slowly, with fluctuations that are remarkably irregular and accompanied by changes in the star's spectrum whose explanation is wholly conjectural. The Astronomical Journal, Nos. 300, 347, 369. 16 EXPLANATORY TEXT. CO CO B tH d 3 3 | O % a S o 00 iO o ^ iH >, rfl r*5 .s PH 3 a O> & 1 bo fc, >^i ^ rr+ O cu S PH o 5 o o> 2 S f S _0 I a o rt -^ r^H CO '- Q *j .5 "r O c H pS 43 o W "^ fa ,-r-J O ^ 5 H^ rv, 1 > ^ CJ 1-^3 ^ O " 1- o C*^ 1 5 rH PH fl I-T^ t * ^ | M Q; a 44 O f*i > > 1 1 t 3 1 S 60 S _g c3 n T3 S CO o ^"^ H ^J C -v cQ bo > -M ] CO "^j f-l 3 2 fl j ) r& * c3 11 2 "0 of H fl K_ li"' .PH ^ C^l I } 1 i o tl' T t S -t-9 -4-3 P 2 S 3 D F^i 111 o fe a, o " 00 * T^ J ! CO "g S o> S Q} TH !>> co ci.. 13 co o ^0 01 t>, 01 oq "S < o 2 j ? s a S co ^ -4^" 4J~ ^H ^H o o e8 0) .. ., c3 d C* IS S 03 JS g J 01 W "i * I j i s 'i TH p i S - i i * ! | g | O OQ [zj M CO I r-J r^ r^ bo 2 o CD 'C ' E 8 8 M PH PH 11.1 g < PH M P 1 j j w ^ ^ g ,5 S J^i HH .2 -~ .2 .2 PH H QJ C3 n i OM f h ao ^ S M HH3 Ig tH 00 C<) C-l CJ 5 b- CO t~ 10 ^H'CO S 01 COOOS Ol - < O CO o 5 CO CM TH CO * 10 "* TH TH CO H* o o "* O} CO C-l ^ 5. 01 TH CO CO CO TH CO q q 00 S" 5 CM Ol o ^ 9 s " 7 0>' CO C-. * Oi t_ CM iO CN) t- iO i^ 3 1Q ^ * ^ ^ iO CO b- ? CM iH rt* V V ^ T ^ 5 ^ 1 T-H - i^J rH V o 1 | s * TH T^ CO ^^ CO "^ t ~ V ^ ^ ^. " ^ CO CO ^ 10 v* CO * r H TH S S PH co CO t- CO OS OS OS Cl S S S CO CO o Tf CO CO b- t- Ol a - IO 00 TH u, *-.i 00 ^ co ^* t- b- O ^ iO TH 01 ^ 05 b- iO os l>: Tin ' -* "* ^ b- U 5 00 K s 1 1 A <*i *~ id 1 LO CO CM CO id cd ^ CO 1 ^ cd co id 1 Tji 1 CO 1 1 CO CD T * 1 * 2 TH CO t-- c. ) 00 o> o CO CM O S pq id >d T-i id id CO Tj3 id CO HH 1 h-T H-T HH 1 1 ^ I 1 1 1 M hH HH ^ ~ ^ H HH > HH H-T HH HH c 1=1 s HH H HH HH t K^ HH , K.^ H 1 4 1 H* HH f> p- HH f> f> H. H HH B O P- T-H CO OS CO CO iO CO -^ CO Tj< Oq s t>* ^^ o^ Ol CO TH CO O t- TH ^ U j ^Sc^ 00 ^ -^SS ct 1C CO S iO if 5 TH O O OO CO iO O} CO CO 15 O CO CO Tjl CO CO CO CO O CM CO -* iH Ol CO T co.lr H TH 4 CO CM ^ CO OS CO 01 CO S TH CO CD T i Oi H CO fi 1 1 1 1 1 1 1 ' 1 I'M" J ~ a t~ OS OS IO TH TH TH CO b (N T^ CO OI TH TH CO OS CM id iO IO CO iO if co in if S O CO O OV O IO CM iO CM CO 00 O iO CD iO TH 00 O Ol CM CO P : oo 5 CO 2 u i4 o o o o O TH 01 OI CO CO **<; P 10 10 CO CO CO CO b- b- b- b- 00 03 TH T- H rH ca H 1 Ceti Andromedae Cassiopeiae Cassiopeiae Andromedae Sculptoris Ceti Trianguli 1 1 1 d> O> o3 PH PH EH Doradus Aurigae 3 .2 LI j h 5 O d -2 .2 H -J3 43 S R M C E8 .2 2 o bo B .a o o ' s .2 a g g 4i o o S g Geminorum Puppis Canis Majori Monocerotis 111 p-;3 S .2 S 8 8 .3 a 13 .S ^ 3J|5 _O 'c? 3 ^ i ffi J> 2 J & EH HH* PH" cj GO PH o ^ * CQ. -< P^ w P- !* H s P- H oc -HHPH& t>^^ .- A^ ^^ r/% ' 6 CM CO Oi rH TH O CM O5 O CM O iH t^ C71 TH * CO T- iO CO t- H O iO O TH ( b- O CO TH b- iO -r)l O TH Oi O CO C i 01 TH TH TH O3 CM T)< CO TH TH TH TH TH T- 00 1 iH 2o3o5c^ ololc^o^ SS3 c^c^^c^^ VARIABLE STARS. 17 TH 1 1 CO 10 t>^ a 1 3 Pn 60 fi eg d c "43 c3 a c 2 1 | ' 1 H 1 (~i "^ ^* ^ 'S cL 1 1^ a & rH, -H fi 13 60 3 8 e i TH aj CD 1 ^ IS a 53 ^ .2' .2 , r-H rrf Tj E 43 1 g JS CO SCO SJ o * B ^ O TH 6O -*H O b CO COCUgCC ^ a -g CO IO TH ^H TH ^ ^ TH J^ ^_j ^ ,_( 1- o O Oa>~.O O-g^ o r- 1 3 ^ OI rf TJ "9 "w 30 to 60 fe 60 L 6O ^ bJO L "^ .5 ^ ^ J * 03 & ,1 CD S j H B n PH rH r^ ^A^^PM^^ si^is: ^ * t- t-. 05 o TH CO 01 CM b- % CO b-GCCOrHCJiCOrHCOCX O b- TH 10 01 C CO CO TH T 5 b- CO ) 1 o CO 00 01 oi co q !3 *| T^ t- iq ^H TH C-l OI O M 5 OlSni'T'iOOst TH COCOb-^iOiOb-^b-^I ^ b- TH ' ; " 1 1 OS b- CO_ w w CO CO TH OS b*\/ 1 lcNicdco'id^~'^idcoid 1 TH'IOTH 1 id\/ c "'c' 5 TH CO H T-H X rH TH IO T-5 CO O TH TH o >0 oo eo CO CO IO IO b- TH O K 5 T- - 1 co oo 1- t- to b- 04 IO O CO ^ O oo idb^ U5THOC> TH Tj(OOOOC ,id^ oo t- co co co 5 IO CO / ^ 1 1 t I 1 >o id id id 1 oi cOb-^| |iOCOcOTH/\ THiOidlcOTHTH'lidl co id o IO *( c; CJ CO t-; 05 b- os os <: > *6 eo id S 10 id TH 10 TH id 10 H M ..*..b- - h ' f> > > r i > > M > !> > > ^M~ > r-T^HH^ t> fc> H r^ K^ 1"^ c 5 CO o rH t- O 1- 10 b- CO CO OI iH^COt-^Oa.iM^ lO^OOCi 31OO1 T H IO "* ** rH >o OI OI TH CO ^^ ^1^ CO T^ ^H C^ ^^ CO ^O ^j^ TH C"$ ^^ IO ^O T < TH OI C 5 CO o C-l O b- .O500OlCCOt-COOOOO^t-C 1 O CO ll o Cl 10 01 C-l i- OI TH OI T^C^^r-(THTH COCMtNC^rH COO 1 ^ iHT^C^C' 5 TH 5 7 1 1 1 1 1 1 1 1 1 1 1 1 1 T H a 00 OS CO ce CO TH CO 10 OrHlOb-THOTHTHlOTHOSCOOIOICOb-OIOIOlTHCOt- t TH H| H TH S3 eS 5 CO eo -t iO TH TH iO THOlTH10THTHrHOlTHlOrHOlTHTHTHO COTHT c 5 01 r. 00 CO H TH -t -t TH 10 10 10 COCOCOCOCOb-b-b-b-b-b-OOOOOOOOCOCC050>CT;OJO - O^ O5 " H T^ H iH rH to ._ .-i .-. 8 C 2 .T-i r-l Q} "^ Q) .2 .2 .2 3 .2 IS .2 ^ "C ' 3 'fi -^ m m fR "i B 2 3| 53 i s g ?c E 1 a u TO ' o CO p w .2 ! S3 C TO 1 ^1 __Q ^ ^ f-| --< O Q3 O g'p-g S .3 S 1 g.2i5SS .H 03 9 coS'i"? S'' i 1 1 1, 1 a J "i,*!* y y 1*1 1,1 !!'!' *"* ' , Jj .2 o'Sn'Sb > 5^ cs 5 TH Oi J C^ -^ c c o TH ie X i o C-1 10 CJ CC CO CO CO b- b-COOSOOTHTHOIOICO^lOCDb-b-b-b-cbcOOTHr H rH r-i - b- t~ 18 EXPLANATORY TEXT. o n $ O Pi 00 g Z ft o >^ f- T3 t C3 s, 0> a 1 GQ o CO CO 7-1 CO CO CO i-l o t- O5 CO Ol CO ^f M sg zZ ~ a pq tO OS t-; OS CO' i i *s li 3 I I CO 1C ", - W ? T f co 1C C I I Ol O 1C C 1C CO 1C O 00 00 1C -^ COOO11C!OCOO>5O^O1OO >* C 1CO1T-I CCO1C>C t- * t- 00 -^ CO CO Ol CO ^ oo o t^ t- in o >n co in CM IH in H S s ^COt-OOO10OOOl>CO3O3CO t-H ^ T^ CO CO ^ 71 Ol *C CO 1C ja OOOTHi-liHi-IOlOlOlCOCO O1O1O1O1O1O1O1O1O1O1O1O1 .^H <** a> i> a e , 43 O O K* O 'S 'a * -2 * S Sooi's a u 1 a" 6 S o CD :3 a. t- o oS o PH H H H no in O3 co 05 T^ b~ co ^^ co co 01 c^ comoooicoooo5t^t-7-io Ol^'ftOb-t-ODCSOOlincO t- t-t-t-t-t-tb-OOCCCOCO DOUBLE STARS. 19 DOUBLE STARS. The double stars in the sky number many thousands. The term is used to include those stars which are within 30" of each other. The eye cannot separate stars unless the distance of the stars is very much greater than this, so that a telescope is necessary for the examination of these objects. A distinction must be made between naked-eye doubles and telescopic doubles, the latter only receiving the name Double Stars. The former are two stars whose separation must be several minutes of arc, as Ursce Majoris in the handle of the Dipper, and e Lyrce. The former is evidently two stars, but the latter is a severe test for the unaided eye, just as the separation of each of its components into two stars is a good test for a telescope. The main components of e Lyrce are distant 3', about the smallest angle which the eye can distinguish. A further distinction must be made between Double Stars and Binaries. The former is a generic term, applying to all stars separated by less than 30". (Some authorities would adopt even a smaller limit, as 15".) The latter is a specific term, and is limited to such double stars as are proved to form a system, the two stars revolving about their common centre of gravity. The aim of the study of double stars is the detection of bin- aries, which is accomplished by observing the changes in the relative position of the component stars. The existence of stellar systems is a definite proof of the universality of attraction, as announced by Newton when he formulated the law of gravitation. In addition to the binaries ocularly revealed by the telescope are those whose com- ponents are so near each other that they cannot be distinguished with the telescope. They have been detected by the periodic doubling of the lines of their spectra, and are known as spectroscopic binaries. In this atlas those double stars only are included the brighter component of which is as bright as the sixth magnitude, and the other as bright as the ninth or tenth magnitude. The list therefore contains those double stars which are seen as single stars with the naked eye, but which may be seen as double with small-sized telescopes. These stars are marked D upon the maps, this letter placed as a subscript to the letter or number designating the star. If the star is without letter or number the D is placed in parenthesis. The following table contains the most interesting double stars of those charted, com- piled from various authorities, with the important facts regarding each. The list includes those which surely form a binary system, and also those which are optically interesting because of contrast of color between their components. The magnitudes of the components are given and the position angle and distance of each pair. The position angle is reckoned from the north point towards the east, the vertex of the angle at the brighter component. The position angles and distances of the stars which are known to be revolving about their common centre of gravity are subject to change ; the values given are necessarily approxi- mate, but are sufficient for purposes of identification. 20 EXPLANATORY TEXT. O = -o 1O oj fl cS s " a a 2 a a a f * 8 5 s 9 9 oo - ~ O rt I ^ "S i J u pq PH PM pq IO 2 B eg s * I I s S 1C O CM O O *f <0 O5 OO t- t- CO T!< CO CO 00 CO 1O CO t- 00 rf ^ * i 10" IO I CO IO t- 00 IO CO CO OO IO TH CO *O Tl< Tj< O t- 00 CO O OO iH N IO iH Oa>O>r5>O>OCOCOCOCOCO - a & a a a 's s o .3 2 .3 " rrt O q .2 ^ 53 E O H III 2 GO r-4 2 .2 j* - 2 o> J? S 1 B e 3 i ' a ? ef .2 C i o o K5 10 DOUBLE STARS. 21 I tn PH M 03 O a) O to 1 1 bo || fo= T^H s TH rt TH ID " 3 .r- rt ^ ^ ft J3 r^ Q3 f3 H ^ n "3 _g 'St _2 ^ "^ _g ' ^3 _J CO ^ - 3 CO '* 3 03 ^1 CO ^ C3 3 li OQ TO 03 42 fl be P* ^ CQ ^ - a ID a S ^H ^J rt ^ O ^"^ <3J M r T^ " hD '^ QJ CJ ID 9 -2 03 C3 p ^ ^ O fl g i. S 03 o> -S fl te CO S "S C3 "*^ - 03 **> S 2 = o O nn "^ -S3 H^> 4? M r3 Q TH fe* I CH P5 H" cs d Q S S 03 te~ .5 2 ^'3 TJ "S bo d S 2 +3 a ^ r-H H OQ S ID H o3 tn o3 t-c o ^j ,p o> o> o> cs - rt >, >,.3 2 &H s^ TH Q) b- 0) ff TH O TH >> > ,fl M TH d <* tO S ^ ^ -S Tj Tj .2-2 g 'o .2 .23 .2 | ^ ^5 g ^^'-SS ^a| S THgc^S .So3o COoS .2tO^(N bfl-S^ ^ -2 i^-S 1 - 1 gg-g^-T 1 T3^3 p^Tj^eTj aobc o.. joo/o .PH CH '*"* pq W "~* *2 i a f riod uncertain DQ I O !O Cl 1 I ID O i pP q ^^ M r4 a p^ PH PH P . ' 0; 3 <1 '2 p^"^ Sft^p, PH T 3 *f 9 ft 0) ID PH ^> ^ . "M ^ ^ . - o5 r^s l>j l>> > t^i -p -0 b f>j r*' 9 >, i-Q c3 p) j c3 c3 ^ c3 c3 ct dO> id< idd*^ 2ddddc 3 d 'o 1 S s S ^ C PH pq H pq pq pq pq pq pq WW^OWOpqpqH O 1 1 TH rH co SO 0~ 10 irT 1 1 1 1 > 1 i i ^ t l 1 II II 1 1 1 t> ^ > > < i I i M M O b- CC CO SO Ci C^l O CO TH b" tO 10 S S S 5 3 S 5 S - S 3 " 3 o T- o rH S CC TH eo 00 CO 00"OSD- a> .,, > 4>o3f> Borealis o o o A S S ^ p3 C S -^ -PH 83 co w CQ ' .2 .2 s 2 '3 fg a '3 jg a '3 _ i '~t 2 g 9 00 S | artrt^OrrtKt-Wrtrtft H M p Q jT^ W o w O O & O O O O O M t^ h^ \~~* h-^ h^ t d 83 d ^ 'o a -*^ 'Sn a 2 'be d ^ 3 'bi) t? S c 9 w B 9 fl 1? M Q C^ M g H ? 5 t-H 1 ! '1-300^0 b^oo^o^ot^pq 43 a O ^s O "o K 1 :q '^ m o $. 1 m "En o G o O sotj^xj," s-e-^-t*^ , ^ b- j,, d ^ ^-f-' 8'M*J.''* 1 a k ^ w UJ, -rH 4. P. 22 EXPLANATORY TEXT. c5 - 1 in W J* 3 1 s 3 S i 04 1 I as 43* 1 ^ - > g >> >> & co " a to ^ t- , pa f GO as co >., g^^ . is g I -1 1 >, S '3 US S i >a ft "^ a> ^ ' ' 3 oc ^ _, g a) TH 00 g S :^ ^ 3 ^ &> 3 o o '3> o 2, "So S S > >> ft ~GO t>^ t>^ 3 !^~ t>- ^^ fcfc! 3 Kfc^ 2 hfc^ f*>>>>^ S ^to^ o3 ^>S*^a5>^ .S'S^ 1 S 9 a S2S'38S'J S S H O 1 M S PQ S PH W O PH S C. 5 .S -2 .S P 2 3 .2 -fi 1 2 2 & 2 jpqpqpq c? WOW H pqpqHW w o i t- "^ < ^41 O | ^ 2] Q CO *O CO W iH CO W5 *O ^ C 5 O^ C^-l iH ^* ^~ ^ J CM TH CO ^ 1 ^^ ^ 1-1 O eo | r-T S . O H J J2 S3 5OO lH S o 5W S "TH S fc &* TH ^ g g ^ C, TH TH N TH ^ CO C 8 " 1* 1" CD H oo (C s ^ t-T T- ,H t~ b H g ^lO-* ^CO t _U5COTH-*CO5O-' > > > a >>>!>>>> >>>. &f fe fef fef fe B O H 1O1OCO COlH ^iHTH-*COS x COOTHO- jTHC^giSctg^^S^SS^^SS X o 3 o H iHcoiMTHTHTHeoo CO>OOTHCMCOC> I^^^ScOTH^^^THTHCOTHCO 00 * a III 1 1 1 K a H O tD Oi C5 O ?D iH CO CO CO GO CO Ci O iH O b- GO O *O CO Y-H ^ O tr- C^l *^* CO C^ C5OiC50OOOOTH < CO CO _CQ c^ ci c3 CJ O D ^< tU FH o o o X en CD CG CO .1-1 ^GQ ^COW^MCOCOO *rH .f- .pH m 1 ,fl ,C ,13 .2 .^ J "22 "^ "^ *^^ 2 Q **^ r 3C3rtC33S3 r IllllllllillllllJ S22fl 8 S6-2-S S ; .2 .2 .2 g rS 'S 'S "5 5 - 15 'S ^ '3 "9 'S CO *W ?" ^JJ> 03,, Sk b P* ^ ^^ S. "^ ^ ^^ Q. J- 1 t~* t '^ TH ^* ' Vl "i. 1^ * **^ ^^ a IH M DOUBLE STARS. 23 1 -3 b tao o i i b o> .1 B o> P< 'i s bbb OT Oa a B a s s s s s c cS 03 c a B o -f ^ o o . 'O O >O lO O O CO CO 00 T-t -* O5 Tf C^ CO iH CO CO rH rH oot-cot-ioeot-t oot-oi co C5t i-HiHTH-^H (NCO i-HrH^lO - - S8 :a a S '? S o 00 24 EXPLANATORY TEXT. USE OF THE STAR ATLAS. The following suggestions are offered for the assistance of those using the atlas for either constellation study or the examination of the sky with the telescope. DESIGNATION OF STELLAR POSITIONS IN THE SKY. The method used by astronomers for designating positions of the heavenly bodies should be understood. This is precisely the same as that of designating positions on the earth by their longitude and latitude. Upon the sky, which appears to us as a sphere, one half of whose inner surface is always visible, we must imagine the equator to be drawn and a system of meridians and parallels to be added. The celestial equator is the trace upon the sky which the plane of the earth's equator would make. As we see it from any point of the earth's surface except the poles, it passes through the east and west points of the horizon, and is inclined to the horizon by an angle which is 90 minus the latitude of the place. Where it crosses the meridian, it is distant from the zenith by an angle equal to the latitude of the place. The sun in its daily path across the sky describes the equator at the time of the equinoxes, about March 20th and September 21st; on other days it describes parallels either north or south of the equator. The pole of the equator is the fixed point in the sky which marks the prolongation of the earth's axis. It is always due north of the observer in the northern hemisphere or due south in the southern hemisphere, and is as many degrees above the horizon as the latitude of the place of observation. Its place is indicated roughly for northern observers by the second magnitude star a Ursce Minoris, or Polaris, and for southern observers by the fifth magnitude star a- Octantis. The great circles, all of which intersect at the pole and are drawn perpendicular to the equator at its several points, like the meridians on the earth, are called in the sky hour circles, not meridians. The term meridian is reserved for the circle passing through the pole and the observer's zenith. Each hour circle in turn momentarily coincides with the observer's meridian, as the earth turns on its axis. The parallels to the celestial equator are drawn precisely as upon the earth. They are called parallels of decli- nation instead of parallels of latitude. Each of the heavenly bodies describes the equator or one of these parallels as the daily rotation of the earth on its axis causes it to move across the sky. One of the best ways of fixing the whole system of circles in the mind is to watch the movements of the heavenly bodies for a few hours on some clear night, having first located the east and west points of the horizon and the position of the pole. Each star in the sky has an hour circle passing through it, just as each point on the earth is upon one of the terrestrial meridians. The distance of the star from the celestial equator is called its declination, north or + if the star is north of the equator, and south or if south of the equator. This corresponds precisely with latitude on the earth. In order to get the other measure corresponding with longitude, it is necessary to select one of the hour circles as a reference circle, just as the meridian passing through Greenwich is chosen on the earth. The hour circle passing through the point on the celestial equator where the sun crosses it in the spring, called therefore the vernal equinox, is selected as the reference hour circle. It is called the equinoctial colure. The hour circle at right angles to this, which therefore passes through the sun's solstitial points in summer and winter, is called the solstitial colure. The angle between the equinoctial colure and the hour circle passing through any star is called its right ascension. It corresponds with longitude on the earth, USE OF THE STAR ATLAS. 25 with the exception that it is reckoned from the equinoctial colure towards the east all the way around the sphere, amounting therefore to 24 hours or 360, while longitude is reckoned both eastward and westward from the meridian of Greenwich and therefore does not exceed 12 hours or 180. Right ascension is usually given in hours, minutes, and seconds instead of degrees, minutes, and seconds, just as is frequently done in expressing terrestrial longitudes. It is a great help to a living appreciation of the system of circles above described and their use in determining the right ascension and declination of the heavenly bodies, if one will take the trouble to estimate the right ascension and declination of any star, and then compare them with the true values given on the chart. To do this it is necessary first to know where the vernal equinox is in the sky, or else the right ascension of some star which can be used instead for reference. In the latter case the difference between the right as- cension of the given star and the reference star is estimated, and this difference added to the known right ascension. It is wise to select for these estimates stars in different parts of the sky. CONSTELLATION STUDY. An acquaintance with the leading star groups is to be recommended not only for itself, but because it gives a clearer idea of the motion of the earth on its axis and about the sun, and also of lunar and planetary movements. It is well, however, to remember that the tracing of the old figures is no part of modern Astronomy, and that little resemblance is to be sought between the names of the constellations and the stars grouped within them. It is very doubtful if the ancient astronomers who invented this method of designating star groups fancied close resemblances between the groups and the names assigned. In only a few cases, notably those of a snake-like figure, as Draco, Serpens, and Hydra, is it possible to detect any resemblance whatever. It is also well to recall that the constellations occupy a very humble position in the modern science of Astronomy, as their use is simply the giving of names to areas in the sky. The chief difficulties to be encountered in studying the constellations arise from their changing positions in the sky due to the earth's daily motion on its axis and its annual motion around the sun. As a result of the former, the same constellation appears tipped at a different angle in one part of the sky than in another a few hours later. As a result of the latter the constellations appear farther westward on any evening than they did at the same time the previous evening. The remedy for these difficulties is to learn the con- stellations with regard to each other and not with regard to the time of day or of year, and certainly not with regard to terrestrial objects. The following plan is suggested for a systematic study of the constellations : 1. Divide the heavens into four grand divisions, bounded by the equinoctial and solstitial colures. Trace these colures in the sky by the prominent stars near which they pass. In the northern sky the seven stars of Ursa Major known popularly as the Dipper will furnish a beginning. The two stars a and ft, forming the side of the bowl of the Dipper and known as the "pointers," will lead to the pole star, a Ursce Minoris, by pro- longing the line from ft to a to about five times its length. The middle star of the seven, 8 Ursce Majoris, at the junction of the handle with the bowl of the Dipper, and the faintest star of the seven, is very near the equinoctial colure. Imagine a line connecting the pole star with 8 Ursce Majoris. It is a portion of the equinoctial colure ; if prolonged from the pole star beyond 8 Ursce Majoris it will intersect the equator at the autumnal equinox. The star 77 Virginia is not far from this point. If prolonged in the other direction from 8 2G EXPLANATORY TEXT. Ursce Majoris beyond the pole star it will intersect the equator at the vernal equinox. There is a line of bright stars easily traced which marks the way, made up of /8 Cassiopeice, a Andromedce, and j Pegasi. The first of these is in the foot of the chair-shaped figure which is the characteristic figure of Cassiopeia ; the second and third form the eastern side of the conspicuous quadrilateral known as the " Square of Pegasus." The vernal equinox it- self is in the relatively starless region south of y Pegasi ; the line from a Andromedce to y Pegasi should be prolonged as far beyond the latter as they are apart. After the equinoc- tial colure has been traced as above, and the vernal and autumnal equinoxes located, the solstitial colure may be similarly traced at right angles to the above. It will lead nearly to 77 Geminorum for the summer solstice, and in the reverse direction to p. Sagittarii for the winter solstice. 2. Learn the zodiacal groups. Each of these has a characteristic figure, by which it may be recognized. The groups are of first importance, because in them lies the ecliptic or the suix's path through the heavens, and also the paths of the moon and leading planets. It is advisable to note from the maps just where the ecliptic itself passes among the stars of these groups. 3. Add the leading constellations north and south of the zodiacal groups, and later the less conspicuous groups. At first only the leading stars should be noted, the fainter ones to be added later if desired. 4. Learn the twenty stars usually known as stars of the first magnitude. The constellations are best learned by their characteristic figures. In order to aid in this study, six smaller maps precede the main maps of the atlas. Their outlines and general plan are precisely the same as those of the larger maps. They contain the stars down to the fourth magnitude, with a few fainter stars where necessary to complete a characteristic figure. In many cases there is no question as to what constitutes the leading stellar figure of any constellation area, but in others different observers may sometimes differ as to the figures. The connecting lines which are drawn upon these maps are intended as guides to help in tracing the characteristic figures. It is to be expected of course that different students will oftentimes prefer different arrangements to those here presented. The student who is interested in the historical development of the subject may profit- ably refer to the larger maps and note the outlines of the old figures in their relation to the actual stellar figures. In order to facilitate the study of the constellations in an orderly way, a rearrange- ment of the constellations according to the four divisions of the sky is here given. The circumpolar constellations of all four divisions can best be studied together, but the equa- torial constellations of the four divisions by themselves. For this reason, the maps of this atlas are arranged as two circumpolar maps, and the intermediate parts of the sky in four divisions bounded by the equinoctial and solstitial colures. The Roman numerals I, II, III, and IV refer to the four divisions respectively. The zodiacal constellations are printed in small capitals, and the other original constellations of Ptolemy's list, which have the most conspicuous figures in the northern sky, in italics. Where a constellation area is partly in one and partly in another division, it is here listed in the division in which the greater part of its area lies. USE OF THE STAR ATLAS. 27 TABLE IX. CONSTELLATIONS ARRANGED ACCORDING TO THEIR POSITION IN THE SKY. NORTHERN POLAR. I. II. III. IV. Cassiopeia Lynx Ursa, Minor Cygnus Camelopardalis Ursa Major Draco Lacerta Perseus Cepheus EQUATORIAL I. EQUATORIAL II. EQUATORIAL III. EQUATORIAL IV. Andromeda Leo Minor Coma Berenices Lyra Triangulum GEMINI Canes Venatici Aquila Auriga CANCER Bootes Sagitta PISCES LEO Hercules Vulpecula ARIES Monoceros Corona Borealis Delphinus TAURUS Canis Minor Ophiuchus Equuleus Cetus Sextans Serpens Pegasus Eridanus Hydra VIRGO Scutum Orion Crater LIBRA SA(iITTARIUS Lepus Canis Major SCORPIUS CAPRICORNUS Sculptor Argo (Puppis) Corvus AQUARIUS Fornax (Malus) Lupus Microscopium Cselum Antlia Piscis Australis Colurnba SOUTHERN POLAR. I. II. III. IV. Phoenix Argo (Vela) Centaurus Corona Australis Horologium (Carina) Norma Grus Hydrus Volans Ara Telescopium Reticulum Chamaeleon Crux Indus Dorado Circinus Tucana Pictor Musca Pavo Mensa Triangulum Australe Octans Apus The names of the months given at the margins of the star maps show the times of year when the constellations can best be studied in the evening. The names are placed be- neath the hour circles which correspond with the meridian at 9 P.M. local time. On the circumpolar maps the names are placed under the hour circles which extend from the pole downward to the horizon at the time named. To illustrate, suppose that the heavens are to be examined October 1st, 9 P.M. Map V shows that at that time the hour circle which marks the right ascension, 21 h. 40 min., nearly coincides with the meridian. The constellations west of the meridian are those west of this hour circle and are given on Map V; those east of the meridian are partly on Map V and Map II. Map I shows how the northern constellations appear to a person in the northern hemisphere when the page is turned so that the date is at the bottom. Cassiopeia is below the pole towards the left, Ursa Major high in the sky above the pole. The following table is given to aid still further in determining the position of the constellations at different times of the year. It gives the right ascensions which coincide with the meridian at 9 P.M. on the dates named. 28 EXPLANATORY TEXT. TABLE X. SIDEREAL TIME AT 9 P.M., OR RIGHT ASCENSION OF THE HOUR CIRCLE WHICH COINCIDES WITH THE MERIDIAN OF THE OBSERVER. January 1 3 ^ 45 m. 15 4 40 February 1 5 47 15 6 42 March 1 7 37 15 8 32 April 1 9h.39m. 15 10 34 May 1 11 37 15 12 33 June 1 13 40 15 14 35 July 1 15 h. 38m. 15 16 33 August 1 17 40 15 18 35 September 1 19 42 15 20 38 October 1 21 h. 41 m, 15 22 36 November 1 23 43 15 38 December 1 1 41 15 2 36 The maps giving the constellations near the equator, Maps II-V, are arranged with the west toward the right and the east toward the left, just as the sky appears to a person in the northern hemisphere when facing south. If the atlas is used in the southern hemi- sphere, the page is to be inverted. The equator is drawn as a horizontal line ; it must be remembered that in the sky it is a semicircle which extends from the eastern point of the horizon to the western point, and that where it crosses the meridian it is distant from the zenith by an amount equal to the observer's latitude. Therefore, if the map is held so that the hour circle which is on the meridian is nearly vertical, the equator at both the left and the right will gradually approach the horizon, touching it at hour circles six hours greater and less than that on the meridian. If one views the constellations facing the east or west, he may turn the atlas so that the equator as drawn will make an angle with the ver- tical equal to the latitude of the place, and the star groups will appear at about the angle which they have in that part of the sky. TELESCOPIC STUDY. The atlas is designed to assist those with small telescopes who may desire to find objects in the sky. For this reason, in addition to the stars readily visible without a tele- scope, the leading clusters, nebulas, double stars, red stars, and variables have been located on the maps. The number of stars of the fainter magnitudes visible in a telescope of only 2 inches aperture is so large that they could not be charted without crowding the maps. The stars charted can be seen with the naked eye and examined themselves, or used as starting-points from which to find the other objects charted. The lists given in the preceding pages contain the leading objects of each class in the sky. It is well to know what can be expected of any given telescope. One of 2 inches aperture will show stars as faint as the 10th magnitude ; of 4 inches aperture, as faint as the 12th magnitude ; of 10 inches aperture, as faint as the 14th magnitude. But stars on the extreme limit of brightness thus stated can be seen only when atmospheric conditions are good and the instrument well focussed for the observer's eye. The dividing power of a telescope in the examination of double stars depends upon the magnifying power used and also upon the steadiness of the atmosphere and the magnitudes of the components. The magnifying power of the telescope under ordinary atmospheric conditions is rarely more than 20 or 30 times the aperture of the telescope in inches. Familiarity with the instru- ment and its different eyepieces will show the observer what eyepieces are best adapted for use under different conditions. Double stars, the distance of whose components is less than 2" or 3". are difficult objects for the amateur to divide with telescopes under 6 inches aperture, especially if the components are bright. The quadruple star e Lyrce is an excel- lent object with which to test the capacity of the telescope for this kind of observing. USE OF THE STAB ATLAS. 29 In order to use the star chart to find objects invisible to the naked eye, when the tele- scope is not provided with setting circles, it is well to know the diameter of the field of view in minutes of arc. This will differ for different eyepieces, diminishing as the magni- fying power increases. It can be determined in several ways, as (1) by estimating the diameter of the field in terms of the diameter of the moon seen with the given eyepiece. The moon's diameter is about 32'. (2) By determining the time which it takes a star to move centrally across the field, the telescope remaining at rest. If the star is near the equator and the time is expressed in minutes and a fraction, simply multiplying by 15 will give the diameter of the field in minutes of arc. If the star is not near the celestial equa- tor,, the resulting value will be too large and must be multiplied by the cosine of the star's declination. When the diameter of the field is known, it is easy to move the telescope from a star towards which the telescope may be directed a sufficient amount to bring the desired object into the field. If the object, for instance a nebula, is on the star map, its distance and direction from a star visible to the naked eye may be estimated, and the former converted into diameters of the field of the telescope. If an object not upon the map is to be examined, for instance a comet, it may be located upon the map by its right ascension and declination, and then its relation to some star determined. Nebulas are usually disappointing objects in a small telescope. The descriptions pub- lished describe them as they appear in very large instruments. Very few of them are suf- ficiently bright to show much detail of structure unless the telescope is of at least 12 inches aperture. The colors of stars are usually not so marked in the telescope as one might expect. The uncorrected color of the telescope itself and the color added by the atmosphere, espec- ially if the star is near the horizon, give a spurious tint which must not be confounded with the real color of the star. It is also very necessary for noting colors of the star that the telescope should be well focussed. The stars marked red are usually of a less pronounced shade of red than the word might seem to indicate. In the use of a telescope too little attention is often given to the firmness of the sup- port of the telescope and to a careful focussing for the individual eye of the observer. Care in these matters will enable the observer to use the instrument to better advantage, and experience will often show that its capabilities are much greater than at first supposed. CHARACTERISTIC CONSTELLATION FIGURES. MAPI RIGHT ASCENSION O^xxiv DECLINATION + 40-+9Q CONSTELLATIONS AROUND NORTfl POLE. BRIGHTER~THAN I^MAQ. 2 MAG 3 MAG. 4A\AG. 5 TH MA& RIGHT ASCENSION O >1 -VI 1 ' MAP II DECLI NATION - 40 - + 40 RIGHT ASCENSION VI K XII K MAP III DECUNATION-40"- 40 ' Tl CRATER BRIGHTER THAN I 5T MAG. I" MA.G. 2 MAG. 3 MAS. 4 T "A\A&. RIGHT ASCENSION, XH h XVIII' MAP IV DECUNATION.-40 -<~4O RI6HT ASCENSION, XVIII - XXIV MAP V OE;CLINATION,-40 *-40 BRIGHTER THAN h T MAG '4'"MAG. 5'"MA& MAP VI RIGHT ASCENSION O h -XXIV h DECLINATION-40--90 CONSTELLATIONS ABOUND 5QUTH MAP I. Right Ascension, Oh XXIVh. Declination,* 40 +S0 SYMBOLS. ... A\ 16 +*x* * "m -'V^ ; V*. % \ A / Q nR I + U V W . * ^ vi^l \*>^p \ v> i. f \ Jik ^J7 ' :4/ i. \ \x I + 4 , *#- \ ^^ ,*- / I +*< ' <^ 49 ,^''T "~~ '-^ ' . _,'^ B) 8 ---V / T"" ; i ' ^1 -- * ~L - ,_- "-- 4 > V O O TO brighter than 1st Mag. % 1st Mag. # ^nd Jlfagr. * 5rd Jtfagr. * 4th Mag. -f 5*ft 6th J V. Declination^- 40 +40" 4O SO xym XVII fainter than 6th Mag. B red. v variable. D double. two stars. S cluster. as nebula. MAP VI. Right Ascension, Oh XXIVh. Declination 40- 90 SYMBOLS. & brighter than 1st Mag. 1st Mag. # 2nd Mag. # 3rd Mag. * 4M Mag. + 5th Mag. 6th Mag. , ~ firr\ o 4QC3 SEP * LIBRARY USB MAR 3 1961 D i_O 1 MM^so 1961 General Library LD 21A-50m-8,'57 University of California (C8481slO)476B Berkeley 188 1