THE GEOGRAPHY OF THE HEAVENS, AND CLASS BOOK OF ASTRONOMY, ACCOMPANIED BT A CELESTIAL ATLAS. BY ELIJAH H. BURRITT, A. M. - *- i* > - REVISED AND CORRECTED BY O. M. MITCHEL, A.M., DIRECTOR OF THE CINCINNATI OBSERVATORY. NEW YORK: PUBLISHED BY HUNTINGTON AND SAVAGE, 216 PEARL STREET. CINCINNATI : H. W. DERBY & CO. 1849. Entered according to Act of Congress/in the year 1848, BY HUNTINGTON & SAVAGE, In the Clerk's Office of the District Court of the United States for the Southern District of New York. o TABLE OF CONTENTS PAOB. Preface to the first edition, . . 7 " Mitchel's edition, ... 11 Preliminary chapter, .... 17 Magnitudes of stars, .... 18 Constellations, ...... 19 Right ascension and declination, 20 Sidereal time, ....... 22 Table for finding meridian pas- sage of objects in mean time, 24 Correction for mean from appa- rent time, ....... 26 Definitions, ........ 26 Greek alphabet, ...... 34 Andromeda, ....... 37 Perseus et Caput Medusse, . . 40 Triangulum, . . ..... 44 Cassiopeia, ........ 45 Pisces, .......... 51 Aries, .......... 55 Cetus, .......... 62 Taurus, ......... 66 Orion, .......... 72 Eridanus, ........ 79 Auriga, ......... 81 Gemini, ..... . . . . 85 Cancer, ......... 90 Canis minor, ....... 93 Monoceros, ....... 95 Canis major, ....... 96 Leo major, ........ 102 Sextans, ........ 107 Hydra, ......... 108 Virgo, .......... 113 Corvus, ......... 118 PAGE. Ursa major, ........ 120 Bootes, ......... 126 Draco, .......... 130 Coma Berenices, ...... 1 34 Canes Venatici, ...... 136 Corona Borealis, ...... 138 Leo minor, ........ 139 The Lynx, ........ 140 Libra, 141 Scorpia, ......... 144 Ursaminor, ....... 148 ....... 153 ...... 155 Sagittarius, . . ...... 157 Scutum Sobieski,' ..... 159 Hercules, ........ 161 Cygnus, ......... 165 Lyra, 170 AquUa et Antinous, . . . .174 Delphinus, 177 Vulpecula et Anser, . . . .179 Serpentarius vel Ophiuchus, .181 Pegasus, 186 Equulus vel Equi Sectio, . .189 Aquarius, 190 Capricornus, 194 Rising, culminating, and setting of the visible constellations in each month, 196 Fixed stars, Parallax, . . . .201 Distances of the fixed stars, . 205 Milky Way, 206 Clusters and Nebula, .... 207 Astral system and central sun, 209 M298706 vi TABLE OF CONTENTS. PAGE, j Solar system, 212 The Sun, 220 Mercury 225 Venus, . 229 The Earth 238 The Moon, 248 Solar, and lunar Eclipses, . . 253 Eclipses of the Sun, .... 255 Eclipses of the Moon, .... 258 Mars, 261 The Asteroids, ...... 264 Jupiter, 270 Saturn, 275 Uranus or Herschel, . . . .281 PAGE. Neptune, 283 Comets, 285 Translation of the sun through space, 296 Law of gravitation, 298 Attractive and projectile forces, 30 1 Precession, 303 Nutation, Aberration, .... 304 Parallax, 305 Refraction, 306 Tides, 307 The Seasons, 312 Astronomical Instruments, . .321 Questions, tables, &c., . . . 324 PREFACE TO THE FIEST EDITION. I HAVE long felt the want of a Class Book, which should be to the starry heavens, what Geography is to the earth ; a work that should exhibit, by means of appropriate delineations, the scenery of the heavens, the various constellations arranged in their order, point out and classify the principal stars, according to their magnitudes and places, and be accompanied at the same time, with such familiar exercises and illustrations, adapted to recitation, as should bring it within the pale of popular instruction, and the scope of juvenile understandings. Such a work I have attempted to supply. I have endeavored to make the descriptions of the stars so familiar, and the instructions for finding them so plain, that the most inexperienced should not fail to understand them. In accomplishing this, I have relied but little upon globes and maps, or books. I very early discovered that it was an easy matter to sit down by a celestial globe, and, by means of an approved catalogue, and the help of a little graduated slip of brass, make out, in detail, a minute (vii) viii PREFACE TO THE FIRST EDITION. description of the stars, and discourse quite fami- liarly of their position, magnitude and arrangement, and that when all this was done, I had indeed given the pupil a few additional facilities for finding those stars upon the artificial globe, but which left him, after all, about as ignorant of their apparent situa- tion in the heavens, as before. I came, at length, to the conclusion, that any description of the stars, to be practically useful, must be made from a careful observation of the stars themselves, and made at the time of observation. To be convinced of this, let any person sit down to a celestial globe or map, and from this alone, make out a set of instructions in regard to some favorite constellation, and then desire his pupil to trace out in the firmament, by means of it, the vari- ous stars which he has thus described. The pupil will find it little better than a fancy sketch. The bearings and distances, and especially, the compar- ative brightness, and relative positions, will rarely be exhibited with such accuracy that the young observer will be inspired with much confidence in his guide. I have demonstrated to myself, at least, that the most judicious instructions to put on paper for the guide of the young in this study are those which I have used most successfully, while in a clear eve- ning, without any chart but the firmament above, I have pointed out, with my finger, to a group of listeners, the various stars which compose this and that constellation. PREFACE TO THE FIRST EDITION. IX In this way, the teacher will describe the stars as they actually appear to the pupil taking ad- vantage of those obvious and more striking features that serve to identify and to distinguish them from all others. Now, if these verbal instructions be committed to writing, and placed in the hands of any other pupil, they will answer nearly the same end. This is the method which I have pursued in this work. The descriptive part of it, at least, was not composed by the light of the sun, principally, nor of a lamp, but by the light of the stars them- selves. Having fixed upon the most conspicuous star, or group of stars, in each constellation, as it passed the meridian, and with a pencil carefully noted all the identifying circumstances of position, bearing, brightness, number and distance their geometrical allocation, if any, and such other de- scriptive, features as seemed most worthy of notice, I then returned to my room to transcribe and classify these memoranda in their proper order ; repeating the same observations at different hours the same evening, and on other evenings at various periods, for a succession of years ; always adding such emen- dations as subsequent observations matured. To satisfy myself of the applicability of these descrip- tions, I have 'given detached portions of them to different pupils, and sent them out to find the stars ; and I have generally had the gratification of hearing them report, that " every thing was just as I had described it." If a pupil found any difficulty in recognizing a star, I re-examined the description X PREFACE TO THE FIRST EDITION. to see if it could be made better, and when I found it susceptible of improvement, it was made on the spot. It is not pretended, however, that there is not yet much room for improvement ; for whoever undertakes to delineate or describe every visible star in the heavens, assumes a task, in the ac- complishment of which he may well claim some indulgence. PREFACE TO MITCHEL'S EDITION. THE extraordinary discoveries which have mark- ed the History of Astronomy, during the last few years, demand corresponding changes in the books designed for the instruction of those who seek a knowledge of this science. Feeling confident that nothing can be more important, than the furnishing of our schools with valuable elementary works in science, I have been induced to undertake the revision and the re- writing of a large part of the well known school book, The Geography of the Heavens. In consequence of the rapid advance in Astronomy, and the important change, which has recently commenced in our country, in the mode of prosecuting its study, this revision has become ab- solutely necessary. When this work first appeared there were very few telescopes in the United States, and of these a very small proportion were employed in the schools and academies, as means of instruction. Hence, at that time, any descrip- tion of the telescopic objects, found within the Xll PREFACE TO MITCHEL'S EDITION. limits of the several constellations, would have been almost useless. Within the last six years a new era in Astronomical science has dawned on our country. A zeal and ardor has been aroused in its behalf, which, at one time, was regarded as quite impossible, in consequence of the peculiar nature of our government and institutions. The reproach cast upon us by Europeans, for our utter neglect of science, if ever just, is no longer so. Only a few years have passed, since the first effort was made to arouse the American people to the importance of the cultivation of Astronomical science, and we now are able to point to no less than three first class observatories, all erected within the last five years, at points widely dis- tant from each other. The example thus set in the West and the East, has prompted to active effort in many parts of our country, and, at this time, there is scarcely a school or college of any rank, at which it has not been resolved to attempt the founding of an Astronomical Observatory, of greater or less magnitude. To meet these rapid changes in the mode of conveying the truths of Astronomy, and to present, in simple and intelligible form, the results of the recent important discoveries r will be the main objects of attention in the revision of this work. A large part of the Mythological notices will be PREFACE TO MITCHEL'S EDITION. Xlll omitted, as less important than the description of telescopic objects found in the various constella- tions. These objects, consisting of nebulae, clusters, double, triple, multiple and binary stars, rich fields and vacant spots, will be noticed, and described, their places given, and drawings of the more im- portant objects, with a note of the diameter of the object glass which will show them, and render their observation possible. Among the new topics treated, we may notice the following as some of the more important. The subject of the binary and double stars, their distances and periods of revolution, has engaged the attention and talent of many of the best As- tronomers of the world, for the last twenty years. These revolving suns will be found to fill- their appropriate places in the revised work. The en- larging of the limits of the solar system, by the discovery of a planet exterior to Uranus, the extra- ordinary means of its discovery, its subsequent history, and the elements of its orbit, constitute a topic of deep interest ; add to this the discovery of five new asteroids, within the last two years, and the perfection of the tables of all the old planets, and we find most important advances in our knowl- edge of the solar system. In the structure of the Sidereal Heavens, and our knowledge of the distribution of the stars in space, B Xiv PREFACE TO MITCHEL'S EDITION. little had been done after the death of Sir W. Herschel, until within the last few years. The dis- covery of the actual distance of a fixed star, by Bessel, gave a new impulse to the investigation of these sublime subjects. This triumph of Bessel was speedily followed by many others, of a like kind. M. Argelander demonstrates the motion of the sun and solar system in space, and fixes the point towards which it is moving ; M. Otho Striive determines its annual angular motion as seen from the fixed stars of the first magnitude ; and, finally, M. Peters, of Russia, fixes the distance of the stars of the second magnitude, from the mean parallax of some thirty stars, deduced from observation. With these data, and the preceding investigations of Sir W. Herschel, M. Striive, of Pulkova, Russia, commences a discussion of the distribution of the stars in space ; the populousness of the Milky Way and the heavens, generally, in stars; determines the relative distances of the spheres of the fixed stars of the different magnitudes ; and, finally, they- abso- lute distances, and the actual velocity of the sun and solar system through space. If we add to these topics the discoveries by Lord Rosse's great reflector, the changes in the views hitherto enter- tained on the subject of La Place's nebular hypo- thesis, and Madler's theory of the great central sun, we find that the last few years have been the PREFACE TO MITCHEL'S EDITION. XV most wonderful, and the most fruitful, in the whole history of Astronomy since the time of Newton. The necessity of a new edition of the Geography of the Heavens need not be urged, after what has been said. To meet the demands, a new set of star charts have been prepared expressly for this work, and the text will be found to conform to these charts. MOUNT ADAMS, May 1st, 1848. THE REVISED GEOGRAPHY OF THE HEAVENS. PRELIMINAEY CHAPTER. THE phenomena of the heavens have excited the curiosity, and fixed the attention, of mankind, in all ages of the world. The beautiful clustering of the bright stars, the moving planets, the extraordinary changes of the moon, the phenomena of the day and night, were themes for study at a period so remote, that neither history nor tradition reach far enough back in the past, to tell us when or by whom, these researches were commenced, or prose- cuted. From the earliest ages, down to the present time, the science of astronomy has presented prob- lems, taxing the highest powers of the human in- tellect, and requiring for their solution the most profound reasoning, the most accurate observation, the most powerful instruments, and an ardor, perse- verance and devotion, which have signalized human effort in no other department of scientific research. " The heavens declare the glory of God," and the successful examination of these same heavens, has most perfectly demonstrated that other great truth, that man has been made " but a little lower than the angels." By the effort of his genius, he has risen to a knowledge of the structure and laws of the universe, he has vindicated the wisdom of God, in the beautiful adjustments of the moving planets, and the harmonious revolutions of a multitude of worlds, linked together by a mysterious bond. He B2 (17) 18 GEOGRAPHY OF THE HEAVENS. has extended the dominion of law to the remote stars, and has computed the periods of these far distant orbs. But these sublime results have not been obtained by any single individual, or by any one nation. The great problem of the universe has been given to the human race, and its solution has been the progressive work of all nations, in all ages, for the last six or seven thousand years. At the end of this vast period, we gather the fruits of all preceding effort, and condense into narrow limits that knowledge, to gain which, has required the highest intellectual activity of the best minds which have adorned the earth. In looking out, of a clear night, on the starry heavens, we find a multitude of brilliant objects, scattered over the sky, without any law or order in their distribution. We readily remark a great dif- ference in the brilliancy of the stars, and our attention is soon fixed upon certain groups of brighter objects, whose configurations, or relative positions, enable us to find them, readily, when they are in the visible heavens. The diversity in brightness has occasioned the classification of the stars, in order of their brilliancy. The brightest occupy the first class, and are called stars of the first magnitude. Of these there are only a few. From the brightest stars down to those just visible to the naked eye, the scale has been so divided that it comprehends six magnitudes, the number of stars in each class increasing as the brightness of the class decreases. We have six magnitudes visible to the naked eye, and then the telescopic stars carry the series down to the sixteenth magnitude, and even still lower. In the description of any star, then, we must always give its magnitude, as one means of fixing its identity. But as there are many stars in each class, the magnitude, alone, would riot serve to point out a particular star. In the early ages 1 ' , PRELIMINARY CHAPTER. 19 of astronomy, the heavens were divided into certain subdivisions, or groups of stars, called constellations; and the figure of some animal, or other object, was assigned, whose outline would embrace all the stars in a given constellation. These subdivisions have been retained in modern times, and although at- tended with many inconveniences, they are too firmly fixed, and too intimately woven, in all works on astronomy, ever to be changed. There is no resemblance between the configura- tion of the stars, and the object, whose name is assigned to the group ; yet when the limits of the constellation, as fixed by the outline of the object whose name it bears, becomes accurately known and laid down on maps, these subdivisions, or constellations of stars, greatly assist in obtaining a knowledge of the heavens. We may even identify a star, by knowing it is the brightest of a given constellation. To render it possible to designate the stars of each constellation, they have been named after the letters of the Greek alphabet, until these are exhausted, calling the brightest star after the first letter, and so on down. In case the num- ber of letters is insufficient to give names to all the visible stars in a constellation, the Roman alphabet is called into use, and after this is exhausted, the Arabic characters, 1, 2, 3, &c., are employed. Thus we call the brightest star in the constellation of the Swan, a Cygni, or Alpha of the Swan; the next brightest in the same constellation is called 3 Cygni, or Beta of the Swan ; Cygnus being the Latin for Swan, and Cygni, meaning of tlie Swan. The same is true of the other constellations, the Latin names being always retained in the designation of the stars. If the constellations contained a very few stars, and those of marked difference of magnitude, this mode of designating them might be sufficient for 20 GEOGRAPHY OF THE HEAVENS. their identification and description. But in con- sequence of the multitude of stars, and the difficulty of distinguishing them from each other by their magnitudes, it has become necessary to fix their positions in the heavens, as the places on the earth's surface are fixed by their longitude and latitude. The corresponding terms applied to heavenly bodies, are right ascension and declination, which terms we proceed to define. To us the sun appears to move among the fixed stars, and in the course of one year to return again to the point of departure. If his track could be mark- ed by leaving behind him a bright line of fire, this line would be found to be a circle traced out among the fixed stars, and this track of the sun is called the ecliptic. There are two points in this track of especial interest, from the fact that on the days when the sun occupies them, the length of the day and night is exactly the same, each being twelve hours. These points, on the ecliptic or sun's track, are called the equinoctial points. The one through which the sun passes in the spring, is called the vernal equinox, that occupied by the sun in autumn is called the autumnal equinox. Each day and night the sun, and other heavenly bodies, appear to describe circles in the heavens, called diurnal circles. They are all parallel to each other. That diurnal circle described by the sun, at either equinox, is called the celestial equator, or the equinoctial. If the equinoctial could be marked by a line of fire in the heavens, it would be found to cut the sun's track, or the ecliptic, in two opposite points, which we have already called the equinoctial points. To fix the place of a star, or other heavenly body, it is referred to the equinoctial, or celestial equa- tor. A star on the north side of the equinoctial is in northern declination, and one on the south side of PRELIMINARY CHAPTER. 21 the same circle is in southern declination. To meas- ure the distance of any object in the heavens, north or south of the equator, an imaginary circle is drawn through the object perpendicular to the equator, and the distance measured on the circle thus drawn from the object to the equator is called its declination. Knowing the declination of a star, north or south of the equator, does not suffice to fix its place in the heavens. It only locates it on the circumfer- ence of a small circle parallel to the equator, and distant from it by an amount equal to the known declination of the object. To fix the exact point of the object on this small circle, it is only neces- sary to know how far the circle, drawn through the object and perpendicular to the equator, cuts the equator from the vernal equinox. This distance measured on the equator, from the vernal equinox round eastward, is called the right ascension. Any circle drawn through a heavenly body, and perpen- dicular to the equator, is called a meridian. That meridian which passes through equinoctial points, is called the prime meridian, or the equinoctial co- lure. Any star, or heavenly body, situated on the prime meridian, has no right ascension, or its right ascension is equal to zero. In case the equator be divided into twenty-four equal parts, and meridians be drawn through the points of division, these meridians are called hour circles. A heavenly body situated on the first hour circle, east of the vernal equinox, has one hour of right ascension ; if it be on the second hour circle, east, it will have two hours of right ascension, and so round, through the twenty- four hours of right ascension to the vernal equinox again. That point in the heavens, directly above us, in which a perpendicular to the surface of still water, carried upward, would pierce the celestial sphere, is called the zenith. If the same perpendicular be 22 GEOGRAPHY OF THE HEAVENS. conceived to pass downward and pierce the lower hemisphere, the point of piercing is called the nadir. The circle perpendicular to the equator, and passing through the zenith of any place, is called the meridian of that place. All points on the earth's surface in the same longitude, will have the same meridian. The instant when the vernal equinox reaches the meridian of any place on the earth's surface, is the beginning of the sidereal day y which terminates when the vernal equinox shall have passed entirely round and returned to the meridian again. A clock, or watch, so regulated as to mark hours at the in- stant when the vernal equinox is on the meridian of a given place, and to mark the hours from to twenty-four hours, is called a sidereal clock, and keeps sidereal time. It will be found that the right ascension (marked R. A.) of each object is given in this work. In case the right ascension of a star is 3 h. 12 m. 10 s., it tells us that it will reach the meridian 3 h. 12 m. 10 s. after the vernal equinox has passed it. If the time, as shown by a sidereal clock, is less than the R. A. of a star, then the star has not yet reached the meridian ; on the contrary, should th^time indicated by the sidereal clock be greater tharHhe R. A. of any object, then the object has already passed the meridian, and is west of it by an amount equal to the difference between the sidereal time and the R. A. To render this clear, take the following examples. The R. A. of a star is 4 h. 26 m. 10 s., the sidereal time is 3 h. 15 m. 25 s. Is the star east or west of the meridian ? It is east of the meridian, and to find the amount by which it is east, From the R. A. = 4 26' 10 Subtract 3 15 25 the time. Diff. = 1 10 45 PRELIMINARY CHAPTER. 23 In case the sidereal time is 5 h. 12 m. 20 s., then the star has already passed the meridian, and is west by an amount found as follows : H. M. S. From the time =5 12 20 Subtract the A. R. =4 26 10 DifE = 46 10 Or the star is h. 46 m. 10 s. west of the meridian. Any one possessing a sidereal time piece, whether clock or chronometer, will find no difficulty in fixing the place of a heavenly body, as to its angular dis- tance east or west of the meridian, at any hour in the twenty-four. The declination of the object, shows its distance north or south of the equator, and combining the two, the A. R. and the Declina- tion, we have the exact position of the object in question. It frequently happens that persons are not provided with sidereal time pieces, but may possess very good solar clocks, chronometers or watches. Mean solar time is reckoned from the instant, that the center of the mean sun (or one moving with the mean motion of the true sun), is on the meridian. It differs from sidereal time, by 3 m. 56.5554 s. in each twenty-four hours, or a sidereal clock gains that amount daily on a mean solar clock. Hence we perceive that mean solar and sidereal time seldom, if ever, agree. When any heavenly body is on the meridian of a given place, a well regulated sidereal clock will show the time exactly equal to the right ascension of the body. No such relation exists between mean solar time and the right ascension. To find the instant that an object, whose right ascension is given, reaches the meridian in mean solar time, or that shown by ordinary clocks and watches, the following table has been computed. 24 GEOGRAPHY OF THE HEAVENS. U's Jan. Feb.) Mir. April. May. June. July. Aug. Sep.. Oct. Nov Dec. h. m. h. m. h. m. h. m. ' b. m. b. in. h. m. h m. h. m b. m. h m h. m 15 14 3 01 1 1223 18 ; 21 27 19 24 17 20 15 15 1 .1 19 11 31 9 35 7 31 25 09 2 57 1 08J23 15 21 23 19 20 17 16 15 ll 13 15 11 27 9 31 727 35 04 2 53 1 04i23 11 21 19 19 16 17 12 15 07 13 12 11 24 9 27 7 22 45 00 2 49 1 01 23 0721 16 19 12 17 08 15 04 13 08 11 20 9 23 7 18 54 56 2 45 57 23 04 21 12 19 08 17 04 15 00 13 0,3 11 17 9 19 7 14 64 51 2 41 53 23 00 21 08 19 04 16 59 14 56 13 01 11 13 9 15 7 09 74 47 2 37 49J22 56 21 04 19 00 16 55 14 52 12 57 11 09 9 11 7 05 8j4 42 2 33 46 22 53 21 00 18 56 16 51 14 48 12 54J11 06 9 07 7 01 9 14 38 2 29 42 22 49 20 56 18 51 16 47 14 44 12 50 11 0-2 9 03 6 56 10 4 34 2 25 38 22 45 ( 20 52 18 47 16 43 14 41 12 47 10 58 8 59 6 52 11 !4 29 a 21 35 22 42'20 48 18 43 16 39 14 3712 43 10 55 8 55 6 47 12 "4 25 2 17 31 22 38:20 44 18 39 16 35 14 33 12 39 10 51 8 51 6 4 J 134 21 2 13 27 22 34, 20 41 18 35 16 31 14 29:12 36 10 47 8 47 6 39 144 162 09 24 22 31 20 37 18 31 16 27 14 2|l2 32 10 43 8 43 6 34 154 12 2 05 2( 22 27 20 33 18 27 16 23 14 22 12 29 10 40 839 6 30 164 OS 2 01 16 22 23120 29 18 2-2 Ifi 19 14 18 12 25 10 3f> 8 35 6 25 174 04 1 57 13 22 20|20 25 18 18 16 15 14 14 12 21 10 32 8 30 6 21 18 3 59 1 54 09 22 16J20 21 18 111 11 14 11 12 18 10 28 8 26 6 16 19 3 55il 50 06 22 1220 17 18 10 16 07 14 07,12 14 10 25 8 22 6 12 203 51 1 46 02 22 08 20 13 18 0616 01 14 03 12 11 10 21 8 18 08 21 '3 47 1 42 23 58 22 05 20 09 18 02 15 59 3 59 12 07 10 17 8 14 6 03 22|3 42 1 38 23 55 J2 01 20 05 17 57 15 55 13 56 12 03 10 13 8 09 5 59 23 3 38 1 34 23 51 21 57 20 01 17 53 15 51 3 52 12 00 10 10 8 05 5 54 243 341 31123 47 21 5319 57 17 49 15 47 13 4811 56 10 06 8 Oi 5 50 25 3 30 1 27 23 44 21 50 19 53 17 45 15 4J 13 4511 53 10 02 7 57 5 45 26326 1 23 23 40 21 46 19 49 17 41 15 39 13 41 11 49 9 58 7 53 5 41 273 21 1 1923 36 21 42il9 45 17 37 15 35 13 37 1 1 45 9 54 7 48 5 36 28 3 17 1 16 23 33 21 38 19 41 17 32 15 31 13 34 11 421 9 50 7 44 5 32 29 3 13 1 14 23 29 21 35 19 37 17 28 15 27 13 30 1 1 38 9 47 7 40 5 28 303 09!.... -J3 25 21 31:19 32 17 24 15 23 13 26 11 35 9 43,7 a' 3 23 31 13 05 .... 23 22 19 28 1 15 19 13 23 9 39|..-- ' 19 A few examples will suffice to explain the use of this table. Given the A. R. of Sirius = 6 h. 38 m. 07 s. required the apparent time of its meridian passage, on January llth. RULE. To the number placed opposite the date, add the A. R. of the star, as found in this work. H. M. S. Thus : A. R. of Sirius = 6 38 07 Tabular No. 4 29 00 11 07 08 PRELIMINARY CHAPTER. 25 Or Sirius passes the meridian at 11 h. 07 m. 08 s. apparent time. EXAMPLE. Required the apparent time of the meridian passage of Vega, on May 30th. A. R. of Vega = 18 31 34 Tabular No. = 19 32 00 Sum = 38 03 34 * Subtract 24 hours 24 00 00 Meridian passage 14 03 34 apparent time. It will be noticed that the foregoing computations have been made for apparent time. This is slightly different from the time shown by clocks and watches, called mean time. Apparent noon is the exact in- stant when the true sun's center is on the meridian. In consequence of the apparent irregular motion of the sun, there is a variable difference between apparent or true time, or that shown by the sun, and mean time, or that shown by the clock. Since we rely for our time on the clock, we here present a table which will exhibit the mean days in the year, on which a clock or watch, regulated to mean time, will be an even number of minutes faster or slower than the sun. From this table it is easy to reduce the apparent time of any meridian passage, found; by the pre- ceding table, to mean or clock time. To be rigidly accurate, the correction should be taken from the nautical almanac, or other accurate ephemeris, but for ordinary gazing these tables are quite sufficient. * In case the sum produced by adding to the tabular number opposite the given date the A. R. of the star, or other heavenly body, be greater than twenty-four hours, from the sum subtract twenty-four hours, and the remainder will be the apparent time of meridian passage. c 26 GEOGRAPHY OF THE HEAVENS. Days. Cor. ID min. Day,. Cor. in linn. Days. Cor. min. Days. Cor. in min. Days. Cor. in min. Days. JSJ Jan. 2 4 F Mar 12 10 F May 1 3 b Aug. 16 4 F Sept. 27 9 S i)ec. j,9 S " 4 5 F " 15 9 F " 15 4 S ' 20 3 F ' 30 10 S '8 S 1 tf 6 F " 19 8 F " 28 3 S 242 F Oct. 3 11 S 107 S " 11 8 F " 22 7 F June 5 2 S " 28 1 F " 612 S 126 S * k 14 9 F " 25 6 F " 11 1 S Sept. 10 " 1013 S 145 S " 16 10 F ' 28 5 F il 15 ' 3 1 S " 14 14 S 164 S 19 11 F April 1 4 F " 19 1 F t; 6 2 S ' 19 15 S 183 S " 23 12 Fj " 4 3 F 24 2 F 9 3 S 2716 S 2012 S 27 1.3 F " 7 2 F 29 3 F ' 12 4 S Nov. 16115 S 22 1 S Feb. 3 14 F 11 1 F Tuly 4 4 F ' 155 S " 2014 S 24 28 13 F " 15 10 5 F ' ; 18 6 S " 2413 S 26 1 F Mar. 4 12 F " 19 1 S " 21 6 F " 21 7 S " 27 12 S 28 2 F ' 8 11 F " 24 2" S A us:. 10 5 F " 24 8 SDec. 310 S 30 3 Fj Now, returning to the examples already given of the meridian passages of Sirius and Vega ; the first of these stars was found to culminate or pass the meridian at 11 h. 07 m. 08s. apparent time, on the lltb Jan. By the last table, on the llth of Janu- ary, the clock is 8 m. faster than the sun. Hence the culmination by the clock will take place at 10 h. 59m. 08s. Again, Vega was found to culminate at 14 h. 03 m. 34s., on the 30th May, apparent time. By the preceding table, on the 28th of May the clock was 3m. slower than the sun, and gaining one minute in 7 days, or about 9s. per day. On the 30th the clock will be slow, about 2 m. 42 s. ; and hence Vega will culminate, by the clock, 14 h. 03 m. 34 s. + 2m. 42s. = 14 h. 06m. 16s. These approximations are sufficiently accurate for ordinary purposes. The first table will not be in error more than 1 m. for twenty years, when the stars will culminate about one minute later than shown by the table. From all the foregoing considerations we deduce the following definitions : The magnitude of a star is its brightness compared with any star assumed as a standard. A star of the 1st magnitude is of the highest order of brightness. PRELIMINARY CHAPTER. 27 All stars below, the 6th magnitude are only rendered visible by telescopic aid. A constellation, is a group of stars falling within the limits of the outline of any animal or object whose name it bears, and whose figure is conceived to be drawn in the heavens, and is actually drawn on globes and maps of the heavens. The ecliptic, is the path which the sun appears to describe in a year among the fixed stars. The equator or the equinoctial, is a great circle cut from the heavens by producing the plane of the earth's equator to meet the celestial sphere. The equinoxes are the points in which the celestial equa- tor and the ecliptic cut each other. Diurnal circles, are those circles which the heaven- ly bodies appear to describe every twenty-four hours. They are all parallel to the equator. Meridians, are great circles perpendicular to the celestial equator, and meeting in the points called the north and south poles of the heavens. Hour circles, are meridians, cutting the equator so as to divide it into twenty-four equal parts ; the first point of division being at the vernal equinox. The zenith, is the point in which a perpendicular to the surface of still water, pierces the celestial sphere above. The nadir ,is where the same perpendicular pierces the celestial sphere below. The meridian of any place, is the great circle, per- pendicular to the celestial equator, and passing through the zenith of the place. The right ascension of a heavenly body, is its distance east of the vernal equinox, -reckoned on the celestial equator. The declination of a heavenly body, is its distance north or south of the equator, measured on a meri- dian passing through the heavenly body. The declination is expressed in degrees, minutes and seconds, of a great circle, and is expressed by 28 GEOGRAPHY OF THE HEAVENS. these symbols, ' ". Thus we write 12 degrees, 17 minutes, 10 seconds : 12 17' 10". A sidereal day ', is the interval from the instant the vernal equinox is on the meridian of a given place, till it again reaches the same meridian. A true solar day, is the interval from the instant the center of the true sun is on the meridian of a given place, till it again reaches the same meridian. A mean solar day, is the interval from the instant that the center of an imaginary sun (moving with the mean daily motion of the true sun) is on the meridian of any given place, till it reaches again the meridian of the same place. The equinoctial colure, is a meridian passing through the equinoctial points. Parallels of declination, are small circles, north or south of the equator, and parallel to it. The rational horizon, is a plane passing through the center of the earth, and perpendicular to the radius drawn to any place on the earth's surface. It divides the heavens into two hemispheres, the upper being the visible, the lower the invisible hemi- sphere. Any heavenly body is in the act of rising, when it passes from below up through the plane of the rational horizon. It is setting, when in the act of passing below this same plane. The sensible horizon, is the circle limiting our view, or where the earth and sky appear to meet. Vertical circles, pass through the zenith, and per- pendicular to the horizon. The prime vertical, is the great circle, which cuts the horizon in the east and west points. Before proceeding to an exploration of the heavens, it will be necessary to acquire some know- ledge of the classes of objects, the individuals of which will be hereafter described. The most ca- sual observer cannot fail, on the first examinaiion PRELIMINARY CHAPTER. 29 of the heavens, to notice an irregular zone, of une- qual brightness, called the Milky Way, which is seen to sweep entirely round the celestial sphere. This bright zone is found to consist of millions of stars, scattered with rich, but irregular profusion, through- out its entire extent. Nearly all its stars are below the sixth magnitude, and are, of course, invisible to the naked eye. But the smallest telescopic aid reveals multitudes of stars ; and as the power of the telescope is increased, the number of stars brought to view increases in a like proportion. Although, according to the investigations of modern science (to be more fully examined hereafter), we may not fix absolute bounds and limits to the mil- lions of stars composing the Milky Way, yet if we confine our examinations to the richer or denser portions, we are able to assign a figure within whose limits the Milky Way will be confined. Were it possible to enclose all the stars composing the Milky Way in some opaque envelope which would shut them out from all space beyond, within this envelope and not very far from its center, our own sun, itself a fixed star, would be found- Having thus enclosed the stars of the Milky Way in imagi- nation, it is found that the space on the outside of this envelope is not void space. Very far beyond this limit, the telescope has revealed objects of greater or less brightness, which, when examined with powerful instruments, are found to consist of millions of minute points, grouped together, and assuming all possible forms, among which the glo- bular manifestly predominates. These are called clusters of stars, and are in many instances so large, as to occupy as much, if not more space than that taken up by the Milky Way, and containing, inall pro- bability, as many stars. These magnificent dusters are so remote, that the telescope may often grasp, at one view, their vast extent, and innumerable millions c2 30 GEOGRAPHY OF* THE HEAVENS. of stars. Other bright objects are seen beyond the limits of the stars composing the Milky Way, which assume all possible shapes, and which, in many respects, resemble the clusters ; with this difference, that no telescopic power has ever revealed any stars within their limits. These are called nebulce, or faint luminous clouds. Among the nebulae, some present characteristics which indicate the fact, that in case they could be examined with greater tele- scopic power, they would be found to be composed of stars too remote to be seen separately, but whose combined light reaches us from their vast distances, and shows them as faint luminous clouds. There are others which exhibit no such characteristics, and which many astronomers believe consist of luminous matter, resembling that composing the tails of comets. These are called irresolvable nebula. In this class, the most remarkable are the planetary nebula, so called from the fact that they present disks, very like those of the planets, with a lumi- nous surface of uniform brightness. They resemble the very distant planets of our system, and are, in some instances, only a little less bright. Among the stars we reckon the following classes, viz. : Single stars, double stars, multiple stars, binary stars, periodical or variable stars, new stars, and nebulous stars. Single stars, are those which, to the naked eye, and under telescopic examination, are found to consist of one individual star. Double stars, are those which, to the naked eye, appear single, but which, under telescopic exami- nation, are found to consist of two stars. Some- times the component stars are equal, at other times they are very unequal, the relative magnitude and distance being different in every set. Multiple stars, are such as are seen single, by the PRELIMINARY CHAPTER. 31 naked eye, but which the telescope finds composed of three or more components. Binary stars, are double stars, in which the com- ponents have been found to be united in such a way that they revolve around each other. These are suns revolving about suns, and not a planet about a sun. Variable stars, are those which are found to under- go certain fluctuations in brightness. Sometimes they are found to lose their light, and actually to become invisible. Then they regain their brilliancy, by slow degrees, and reach their original brightness. In some individuals these changes are accomplished in a certain fixed period ; in other cases the fluctu- ations of light are not governed by any known law. New stars, are those which have suddenly blazed 'forth in some region of the heavens previously blank or vacant. They generally die away and disappear in the course of one or two years. Nebulous stars, are such as are surrounded by a faint halo, or luminous haze of nebulous matter. It will be readily remarked that all these objects, except the single stars, are telescopic, and are invi- sible to the naked eye. The region in the heavens about four degrees on each side of the ecliptic, or sun's path, is called the zodiac, and is remarkable as the region in which the sun, moon, and large planets perform their revolutions among the fixed stars. The constella- tions, into which the stars in the region of the zo- diac were divided, are doubtless among the most ancient in the heavens. In consequence of the apparent annual motion of the sun among the con- stellations of the zodiac, the stars of these constel- lations will be successively lost in the superior brilliancy of the sun, and will become invisible while in the immediate vicinity of the sun. This remark is true of all the constellations beyond the 32 GEOGRAPHY OF THE HEAVENS. limits of the zodiac, and near enough to the sun's track to be above the horizon with the sun, and to be extinguished by his light. As we approach the north pole of the heavens, we find certain groups of stars or constellations which never sink below the horizon, and are consequently visible at all seasons of the year. Others, more remote from the north pole, sink below the horizon, and disappear for only a short time. As the stars about the south pole of the heavens never rise above the horizon of any place in our northern latitudes, they are never visible to us ; and to be seen to advantage, the spectator must travel to southern latitudes. The Atlas which accompanies this work, contains detailed maps of all the principal constellations, involving the stars down to the sixth magnitude, inclusive, the principal clusters, nebulae, double stars, &c. The constellation exhibited on any map, is, in general, surrounded by its bounding constella- tions, so as to show their relative positions. This necessarily occasions the repetition of certain con- stellations on several maps. But the map intended for use, in the study of each constellation, is referred to in the text describing the constellation. As each judicious instructor will select his own method of teaching the constellations to his classes, it has been thought best not to arrange this work with reference to one invariable plan, which must be followed to render it useful. It is, in general, better to study a constellation, when it occupies a position in the heavens far enough above the hori- zon to render all its stars visible. This can only occur at a certain season of the year ; and as classes will commence the study of astronomy at any con- venient time, this work is so arranged that the teacher can commence at any constellation which may be favorably situated for examination at the PRELIMINARY CHAPTER. 33 time when his class enters upon the study of the heavens. In teaching the constellations, it is certainly best to commence with some one in which the principal stars are large and brilliant, and thus easily recog- nized ; such as the stars in Ursa Major, or in Lyra, or in Orion, or in Taurus. Having adopted any point of departure easily recognized, it will not be difficult to refer the surrounding constellations to this point, and gradually to extend the examina- tion until it embraces the whole visible heavens. The maps present, as nearly as may be, pictures of the heavens, as seen with the naked eye. A faint outline of the figure whose name the constel- lation bears, is found on the map ; not so prominent as to become the striking object, but sufficiently distinct for all useful purposes of reference. These outlines must be retained, as the stars are most readily described, and their places found, by their positions in the constellation. Thus we speak of the bright star Albireo, in the Ull of the Swan ; Al- debaran, in the eye of the Bull, &c. ; and by the lo- cality thus given, the eye seizes the object on the map at a glance. The parallels of declination and the hour circles have not been drawn on the map, to prevent con- fusion ; but the degrees of declination are marked on the right and left of the map, and the hours of Right Ascension at the top and bottom. Hence it is easy to determine, from the maps, the A. R. and Dec. of any object. The double stars are at once recognized, on the maps, by being double and round, while all other stars are stellated or star-shaped. The nebulae and clusters are readily distinguished as small faint objects, on the maps. We commence with the constellations upon and to the east of the prime meridian, and shall trace 34 GEOGRAPHY OF THE HEAVENS. them in the order in which they appear to reach the meridian, going eastward round the celestial sphere. As Greek letters so frequently occur in catalogues and maps of the stars, and on the celestial globes, the Greek alphabet is here introduced for the use of those who are unacquainted with it. The capi- tals are seldom used for designating the stars, but are here given for the sake of regularity. A B r A E z H I K A M N s O n P S T T * X * ii To find in what part of the heavens to look for a constellation, at any season of the year and hour of the night, examine the map, and note the mean right ascension of the constellation in question. Then find by the rule (page 14) the meridian pas- THE GREEK ALPHABET. a Alpha a ft Beta b y Gamma g s Delta d e Epsilon e short f Zeta z n Eta e long Theta th * Iota i x Kappa k X Lambda 1 /* Mu m V Nu n | Xi x O micron o short n Pi P p Rho r f Sigma 8 f Tau t v Upsilon U t Phi ph 2 Chi ch 4* Psi ps to Omega o long PRELIMINARY CHAPTER. 35 sage of the mean right ascension of the constella- tion on the given day. In case the time at which you seek the constellation is later than the time of meridian passage, then the center of the constella- tion has passed the meridian; on the contrary, should it be earlier, the constellation is east of the meridian, and its angular distance from the meri- dian will be expressed by the difference between the time of meridian passage of the center point of the constellation and the time of examination. EXAMPLE. Where must we look for the constel- lation Andromeda, at ten o'clock, p. M., on the 12th of October ? From Map No. 1, the right ascension of the middle point of this constellation is about one hour. H. M. 8. A. R. of the middle point, = 1 00 00 Tab. No., = 10 51 00 Sum = 11 51 00 Time, 10 o'clock, subt., 10 00 00 1 51 00 The center of the constellation is, therefore, Ih. 51m. east of the meridian ; and as the mean declination, shown by the map, is about 40 north, its place may be readily found in the heavens. It will be well for the student to fix in the heavens some standard of measure, in degrees and in hours. Each hour of right ascension contains fifteen de- grees of arc. The distance from the zenith to the horizon is 90, or one quarter of the whole circum- ference. If this distance be divided by the eye into six equal parts, each of these parts will be 15. It should be remembered that hours of A. R. are always measured on the equator, and the hour circles are just 15 apart at the equator, but con- verge to a point at either pole. Hence the space 36 GEOGRAPHY OF THE HEAVENS. intercepted on the parallels of declination by two adjacent hour circles, grow smaller the farther the parallel is from the equator, either north or south. In the notices of the double and binary stars, the distance of the components, and the angle formed by a line drawn from the center of the larger com- ponent through the center of the smaller one, with the meridian, counting from the north to the east round the circle, are given, with the date or epoch at which the given distance and position were ob- served. It is by means of measures of the distances and angles of position, that it becomes possible, after many years of observation, to compute the curves which the binary stars describe, in their orbitual motion around their common center of gravity. In the description of the components, the largest star is called --.---- A, The next in size, - - - B; and if there be more components than two, as is the case with multiple stars, they are named A, B, C, D. &c., in the order of magnitude. In many instances there is a marked difference in the color of the components of double and mul- tiple stars. Whenever this difference is readily recognized, the colois are given in the description of the components. CONSTELLATION OF ANDROMEDA. 37 CHAPTER I. DIRECTIONS FOR TRACING TFIE CONSTELLATIONS ON MAP NO. I. ANDROMEDA. PERSEUS ET CAPUT MEDUSAE. TRIANGULUM. THE TRIANGLE. CASSIOPEIA. Favorably situated for examination in November, De- cember, and January. ANDROMEDA. If we look directly over head at 10 o'clock, on the 10th of November, we shall see the constellation celebrated in fable, by the name of ANDROMEDA. It is represented on the map by the figure of a woman having her arms extended, and chained by her wrists to a rock. It is bounded N. by Cassiopeia, E. by Perseus and the head of Medusa^ and S. by the Triangle and the Northern Fish. It is situated between 20 and 50 of N. declination. Its mean right ascension is nearly 15, or one hour E. of the equinoctial colure. It consists of 66 visible stars, of which two are of the 2d magnitude, and two of the 3d; most of the rest are small. The stars directly in the zenith are too small to be seen in the presence of the moon, but the bright star Almaack, marked y, of the 3d magnitude, in the left knee, may be seen 13 due E., and Merach, marked , of the 2d magnitude, in the girdle, 7 south of the zenith. This star is then nearly on the meridi- an, and with two others N. W. of it, form the girdle. D 38 GEOGRAPHY OF THE HEAVENS. The three stars forming the girdle are of the 2d, 3d, and 4th magnitude, situated in a row, 3 and 4 apart, and are called ,3, i", and v . If a straight line, connecting r with $ be pro- duced southwesterly, 8 farther, it will reach to 6, a star of the 3d magnitude, in the left breast. This star may be otherwise known by its forming a line. N. and 8., with two smaller ones on either side of it ; or by its constituting, with two others, a very small triangle, S. of it. Nearly in a line with r , /3 and 5, but curving a little to the N., 7 farther, is a lone star of the 2d magnitude, in the head, called Aipheratz, or a An- dromeda. This is the N. E. corner of the great f< Square of Pegasus," to be hereafter described. It will be well to have the position of Aipheratz well fixed in the mind, because it is but one minute W. of the great equinoctial colure, or first meridian of the heavens, and forms nearly a right line with a, in the wing of Pegasus, 14 South of it, and with 3, in Cassiopeia, 30 N. of it. If a line, con- necting these three stars, be produced, it will terminate in the pole. These three guides, in con- nection with the North Polar Star, point out to as- tronomers the position of that great circle in the heavens from whiph the right ascension of all the heavenly bodies is measured. Bode has registered 226 stars in Andromeda. TELESCOPIC OBJECTS. A DOUBLE STAR. A. R. = h. 1 m. 43 s. Dec. -f- 25 01' 2", on the crown of Andromeda's head, in a coarse cluster. A 10, B 11 mag., both reported pale blue. According to Sir William Herschel, this star is surrounded by extensive nebulosity, exceedingly faint and diffused. No outline has yet been given by even the most powerful instruments. Pos. 120 0'. Dist. 28".00. Epoch 1836.81. 22 ANDROMEDA. A. R. = h. 2 m. 2 s. Dec. -f- 45 IQf 9", a fine double star, in the Milky Way, between the left hand of Andromeda and the head of Cassiopeia. A 5, B 8 magnitude. CONSTELLATION OF ANDROMEDA. 39 Stationary. Pos. 85 5'. Dist. 4". 7. Epoch 1835. v ANDHOMEDJE A. R.= h. 28 m. 21 s. Dec. = 32 50'. A coarse double star, on the left breast of Andromeda. A 4, B 9 magnitude. Stationary. Pos. 173 9'. Dist. 35". 6. Epoch 1832.90. THE GREAT NEBULA IN ANDROMEDA. A. R. = h. 34 m. 5 s. I) ec- _|_ 40 23' 6". Known as far back as 905 A. D., and of course discovered by the naked eye. Besides being the oldest nebula on record, it is the only one fairly visible without the aid of the telescope ; yet to see it requires a keen eye, and a pure atmosphere. It was rediscovered by Simon Marius, with the unaided eye, and first examined by him with the telescope, on the 15th Dec., 1612. Owing to the variety in the power of the telescopes used by different observers, in the examination of this object, it has received great diversity of description ; some call it round, others oval. Cassini thought it nearly triangular. Sir William Herschel considered this the nearest of all the great nebu- Ise ; on what ground I know not, unless it be its apparent magnitude. He considers its distance to be about two thousand times the distance of Sirius! and if Sirius be as remote as 61 Cygni, then would the light of this object require no less.than twenty thousand years, at twelve million miles per minute of time, to reach us. Such periods and distances are not more overwhelming than the magnitude of the object under exam- ination. Great as the above distance may appear, in case we are to re- gard this mi4y light as an aggregation of millions of distant suns, we must sink it vastly deeper in space, to reconcile the hypothesis with the fact that the stars which compose it have never been revealed by the most powerful instrument. There is a small attendant, or companion, discovered by Le .lentil in Nov., 1749, which has been partially resolved into stars by Lord Rosse's three feet Reflector. The drawing was made while under inspection with the twelve inch Refractor of the Cincinnati Observatory. 36 ANDROMEDJE. A. R. = h. 46 m. 24 s. Dec. -f- 22 45' 7". A very close double star, in the right elbow of Andromeda. A 6, B 7 magnitude ; both of a golden color. The measures indicate a binary character. Pos. 307 04' Dist. 0".90 Epoch 1830.78 Herschel. 320 47 .937 1836.90 Struve. 322 9 1 .000 1843.12 Smyth. 330 14 1 .050 1847.70 Mitchel. ju. ANDROMEDA. A. R. = h. 47 m. 53 s. Dec. -}- 37 37' 8". A wide double star in the girdle of Andromeda. A 4, B 16 magnitude. Pos. 110- 28'. Dist. 49". 19. Epoch 184267, Challis. This object is difficult, in consequence of the minute size of the companion. 55 ANDROMEDA. A. R. = 1 h. 43 m. 42 s. Dec. =-j- 39 56' 2". A delicate double star on the left leg of Andromeda. A 5, B 16 40 GEOGRAPHY OF THE HEAVENS. magnitude. Discovered by Herschel, and marked as " a fine specimen of a nebulous star." Pos. 350 0'. Dist. 25". 0. Epoch 1832.95. y AXDROMED.E. A. R. = 1 h. 54 m. 06 a. Dec. =-}- 41 33' 6". A magnificent triple star on the left knee of Andromeda. A 3^, B and C combined make a star of 5 magnitude. This star was known to be double as far back as 1778. The star was examined and measured as double by all subsequent observers down to Struve, who in 1812, with the great refractor of the Pulkova observatory, first divided the small star into two, making it a triple set. The distance between the close green stars cannot exceed '.4, and to see it fairly double requires a most power- ful instrument. I obtained many measures of this object, and succeeded in dividing the stars, clearly, showing a difference in the magnitude of the components. The measures of angles of position, agree remarkably well with each other, and give the pos. 1 10 C 00'. Dist. 0".40. Epoch 1 846.fi. It is worthy of remark, that the first examinations of this object, made by myself, were with a diminished aperture. These were unsuccessful, and it was only after the full aperture was employed that the stars were clearly divided. This division requires a capital atmosphere, and a smooth clock motion, for its accomplishment. * Pos. A to B, 62 9'. Dist. 10". 6. Epoch 1837.80. AT* ELONGATED NEBTTLA. A. R. = 2 h, 12m. 35 s. Dec. = -f- 41 36' 1". On the right foot, a little above a line drawn from $ Persei to y Andromedae, at about two-thirds the distance from the first star. It very much resembles an annulus seen very obliquely. It was discovered by Miss Caroline Herschel, in August 1783, with a very ordinary reflector, and a power of thirty times. The dark space along the greater axis, was clearly seen by Sir William Herschel, and he regarded the object as an immense ring of myriads of stars, so remote that their individuality was lost under his greatest space-penetrating power. PERSEUS, ET CAPUT MEDUSA. PERSEUS is represented with a sword in his right hand, the head of Medusa in his left. It is situa- ted directly N. of the Pleiades and the Fly, between Andromeda on the W. and Auriga on the E. Its mean declination is 49 N. It is on the meridian the 24th of December. It contains, including the head of Medusa, 59 stars, one of which is of the 2d magnitude, and four of the 3d. According to Eu- dosia, it contains, including the head of Medusa, 67 stars. CONSTELLATION OF PERSEUS. 41 " Perseus next, Brandishes high in heaven his sword of flame, And holds triumphant the dire Gorgon's head, Flashing with fiery snakes ! the stars he counts Are sixty-seven , and two of these he boasts, Nobly refulgent in the second rank One in his vest, one in Medusa's head." THE HEAD OF MEDUSA is not a separate constella- tion, but forms a part of Perseus. It is represented as the trunkless head of a fright- ful Gorgon, crowned with coiling snakes, instead of hair, which the victor Perseus holds in his hand. There are, in all, about a dozen stars' in the Head of Medusa ; two of the 4th magnitude, and one, varying alternately from the 2d to the 4th magnitude. This remarkable star is called Algol, and marked /3. It is situated 12 E. of y , in the knee of Andromeda, and may be known by means of three stars of the 4th magnitude, lying a few degrees S. W. of it, and forming a small triangle. It is on the meridian the 21st of December ; but as it continues above the horizon 18 hours out of 24, it may be seen every evening from September to May. It varies from the 2d to the 4th magni- tude in about 3j hours, and back again in the same time ; after which it remains steadily brilliant for 2f days, when the same changes recur. The periodical variation of Algol was determin- ed in 1783, by John Goodricke of York (Eng.) to be 2 days, 20 hours, 48 minutes, and 56 seconds. Dr. Herschel attributes the variable appearance of Algol to spots upon its surface, and thinks it has a motion on its axis similar to that of the sun. He also observes, of variable stars generally : " The rotary motion of stars upon their axes is a capital feature in their resemblance to the sun. It appears to me now, that we cannot refuse to admit such a motion, and that indeed it may be as evidently prov- ed as the diurnal motion of the earth. Dark spots, D2 42 GEOGRAPHY OF THE HEAVENS. or large portions of the surface less luminous than the rest, turned alternately in certain directions either towards, or from us, will account for all the phenomena -of periodical changes in the luster of the stars, so satisfactorily, that we certainly need not look out for any other cause." It is said that the famous astronomer Lalande, who died at Paris in 1807, was wont to remain whole nights, in his old age, upon the Pont Neuf] to exhibit to the curious the variations in the brillian- cy of the star Algol. Nine degrees E. by N. from Algol, is the bright star Algenib, marked a, of the 2d magnitude, in the side of Perseus, which with y Andromeda, makes a perfect right angle at Algol, with the open part towards Cas- iopeia. By means of this strikingly perfect figure, the three stars last mentioned may always be re- cognized without the possibility of mistaking them. Algenib may otherwise be readily distinguished by its being the brightest and middle one of a number of stars lying four and five degrees apart, in a large semicircular form, curving towards Ursa Major. Algenib comes to the meridian on the 21st De- cember, 15 minutes after Algol, at which time the latter is almost directly over head. When these tw r o stars are on the meridian, that beautiful cluster, the Pleiades, is about half an hour E. of it ; and in short, the most brilliant portion of the starry heav- ens is then visible in the eastern hemisphere. The glories of the scene are unspeakably magnificent ; and the student who fixes his eye upon those lofty mansions of being, cannot fail to covet a knowledge of their order and relations, and to " reverence Him who made the Seven Stars and Orion." The Milky-Way around Perseus is very vivid, being undoubtedly a rich stratum of fixed stars, pre- senting the most wonderful and sublime phenom- enon of the Creator's power and greatness. Koh- CONSTELLATION OF PERSEUS. 43 ler, the astronomer, observed a beautiful nebula near the face of Perseus, besides eight other nebu- lous clusters in different parts of the constellation. Bode has registered 196 stars in this constellation. TELESCOPIC OBJECTS. 76 M. PERSEI. A. R. = 1 h. 32 m. 16s. Dec = -f 50 46' 5", an oval white nebula, close to the toe of Andromeda, though in the limits of Perseus. Discovered by Mechain. Messier pronounced it a compressed cluster ; while Herschel thought it a double irresolvable nebula. With the Northumberland Equatorial, Cambridge, Eng. it has a spangled ap- pearance. Prof. Challis says " the resolution is very doubtful." A MAGNIFICENT CLUSTER. A. R. = 2 h. 07 m. 58 s. Dec. -j- 56 24' 4". In the sword handle of Perseus. This is certainly one of the most brilliant and beautiful objects in the heavens ; under favor- able circumstances, the field of view glows and sparkles with innumer- able diamonds, on a ground dark and rich as the blackest velvet. In the center, five stars are arranged in the form of a bow strongly bent, while a bright 8th mag. star is situated precisely at the point where the thumb and finger would hold the arrow. This cluster is considered by Sir W. Herschel, and with reason, as a protuberant portion of the Milky- Way, or vast stratum of stars of which our own sun is an individual With the full aperture of the 12 inch Refractor, all haziness disappears, and the heavens beyond are completely dark and pure, showing that the vision has pierced entirely beyond the limits of space occupied by these stars, and that the interval between them and the nearest group beyond is so great as to hide them absolutely from the view. No drawing can give any idea of the splendor of this object. The one which accompanies this description was taken with care, and gives a correct idea of position and relative magnitude, but not of the sparkling beauty of the stars. Ax ELONGATED NEBULA. A. R. = 2 h. 30 m. 25 s. Dec, _|_ 38 2 1' Near the head of Medusa. Discovered by Herschel, 1 786. This is probably one of those stupendous rings of stars forming a separate universe, like our own, and seen under great obliquity. S. PERSEI. A. R. =2 h. 33m. 8s Dec = 48 32' 9", A Tri- ple star on the left shoulder of Perseus. A 4, yellow ; B 1 3, violet ; C. 11, gray. No change in position seems to have occurred since first discovered by Herschel in 1782. Dist. A to B = 15" A to C = 27" * PERSEI. A. R. = 2 h. 39 m. 04 s. Dec. = 55 13' 5". A double or rather multiple star on the head of Perseus. A 5, orange ; B 8 $, blue. There are many stars in the field. The principal one has three small stars on one side, and one on the other, all nearly in the same straight line, and forming a miniature of Jupiter and his satellites. 44 GEOGRAPHY OF THE HEAVENS. No change in position, yet detected. PERSEI, Algol A. R. 2 h. 57 m. 46 s. Dec. = _|_ 40 20' A coarse double star in the head of Medusa, on the shield of Perseus. A 2 to 4 mag. B. 1 1. This is the most wonderful among the variable stars. The rapidity and regularity of its changes, the great amount of change in brilliancy, and its double character, mark it as a most extra- ordinary object.-^It diminishes from the 2d to the 4th magnitude in about 3^ hours, retains its diminished splendor about 18 minutes, and in 3^ hours resumes by degrees its former splendor. Its period is '2d. 20 h. 48 m. 56s. PERSEI. A. R. == 3 h. 47 m. 08 s. Dec. = -|- 39 32' 4", a fine double star near the left leg of Perseus. A 3g, B 9. Discovered by Herschel. Pos. = 832 / Dist. = 8'.00 Ep. 1780.59 Herschel. A COMPRESSED GROUP. A. R. = 3 h. 58 m. 11s. Dec. = -|- 49 04' in the left knee of Perseus. First registered by Herschel 1 790. TRIANGULUM. The Triangle is supposed to have derived its name from the Egyptian Delta. Formerly there was but one Triangle ; a second was added by Hevelius, and is retained on the map. The Triangles are situated between the head of Aries, on the south, and the knee of Andromeda, on the north. They contain one star of the third, and one of the fourth magnitude. The other stars are small. Ptolemy reckoned, in this constellation, four stars ; Hevelius, nine ; Piazzi, twenty-five; and Bode has registered thirty-three stars. Most of them are tele- scopic. TELESCOPIC OBJECTS, A LARGE FAINT NEBULA A. R. = 1 h. 24 m. 51 s. Dec. -f- 29 51' 03"; between the head of the Northern Fish and the Triangle. Discovered by Messier, 1764; resolved by Herschel, 1783, into minute stars. He locates this object in the 334th order of distances, or regards it as 334 times more remote than stars of the first magnitude. CONSTELLATION OF CASSIOPEIA. 45 i TRIAXGULI. A. R.=l h. 53 m. 38 s. Dec = -f- 32 30' 05". A close double star on the triangle. A 5, B 15, mag. Discovered by Strive. Pos. 110 0' Dist. =5" Epoch 1835.75 Smyth. / TRIANGULI, A. R. = 2 h. 3m. 06 s. Dec. = -|- 29 33'. A close double star, under the base of the triangle. A 5-, " topaz yellow," B 7, "green." Discovered by Herschel. Recent measures indicate fixity in the components. Pos. 77 50' Dist. 30".598 Epoch 1830.97 Struve. A CLOSE DOUBLE STAR. A. R. = 2 h. 19 m. 26 s. Dec. = -j-29 12' 05". Between the Fly and Triangle. A 6, B 10. Discovered by Struve. Pos. 340 40 7 Dist l".903 Epoch 1332.36 Struve. ';'.' CASSIOPEIA. This constellation is situated 26 N. of Androm- eda, and midway between it and the North Polar Star. It may be seen, from our latitude, at all hours of the night, and may be traced out at almost any season of the year. Its mean declination is 60 N. and its right ascension 12. It is on our meridian the 22d November, but does not sensibly change its position for several days ; for it should be remembered that the apparent motion of the stars becomes slower and slower as they approximate the poles. Cassiopeia is a beautiful constellation, contain- ing 55 stars that are visible to the naked eye ; of which one is of the 2d and four are of the 3d mag- nitude, and so situated as to form, with one or two smaller ones, the figure of an inverted chair. " Wide her stars Dispersed, nor shine with mutual aid improved ; Nor dazzle, brilliant with contiguous flame : Their number fifty-five." 46 GEOGRAPHY OF THE HEAVENS. Caph, /3 Cassiopeia, in the garland of the chair, is almost exactly in the equinoctial colure, 30 N. of Alpheratz, a Andromeda, with which, and the Polar Star, it forms a straight line. Caph is therefore on the meridian the 10th of November, and one hour past it on the 24th. It is the westernmost star of the bright cluster. Schedir, a Cassiopeia, in the breast, is the uppermost star of the five bright ones, and is 5 S. E. of j3 : the other three bright ones, forming the chair, are easily distinguished, as they meet the eye at the first glance. There is an importance attached to the position of j3 that concerns the mariner and the surveyor. ' It is used, in connection with observations on the Polar Star, for determining the latitude of places, and for discovering the magnetic variations of the needle. It is generally supposed that the North Polar Star, so called, is the real immovable pole of the heav- ens ; but this is a mistake. It is so near the true pole that it has obtained the appellation of the North Polar Star ; but it is, in reality, more than a degree and a half distant from it, and revolves about the true pole every 24 hours, in a circle whose radius is 1 31'. It will consequently, in 24 hours, be twice on the meridian, once above, and once below the pole : and twice at its greatest elongation E. and W. The polar Star not being exactly in the N. pole of the heavens, but one degree and 31 minutes on that side of it which is towards Caph, the position of the latter becomes important, as it always shows on which side of the true pole the polar star is. There is another important fact in relation to the position of this star. It is equidistant from the pole, nnd exactly opposite another remarkable star in the square of the Great Bear, on the other side of the pole. It also serves to mark a spot in the starry ^* CONSTELLATION OF CASSIOPEIA. 47 heavens, rendered memorable as being the place of a lost star. Two hundred and sixty-six years ago, a bright star shone 5 N. N. E. of Caph, where now is a dark void ! On the 8th of November, 1572, Tycho Brahe and Cornelius Gemma saw a star in the constellation of Cassiopeia, which became all at once, so brilliant, that it surpassed the splendor of the brightest pla- nets, and might be seen even at noonday ! Gradu- ally, this great brilliancy diminished,* until the 1 5th of March, 1573, when, without moving from its place, it became utterly extinct. Its color, during this time, exhibited all the phe- nomena of a prodigious flame first it was of a dazzling white, then of a reddish yellow, and lastly of an ashy paleness, in which its light ex- pired. It is impossible, says Mrs. Somerville, to imagine any thing more tremendous than a confla- gration that could be visible at such a distance. It was seen for sixteen months. Some astronomers imagined that it would reap- pear again after 150 years ; but it has never been discovered since. This phenomenon alarmed all the astronomers of the age, who beheld it ; and many of them wrote dissertations concerning it. Rev. Professor Vince, one of the most learned and pious astronomers of the age, has this remark : " The disappearance of some stars may be the destruction of that system at the time appointed by the DEITY for the probation of its inhabitants ; and the appearance of new stars may be the forma- tion of new systems, for new races of beings then called into existence, to adore the works of their Creator." Thus, we may conceive the Deity to have been employed from all eternity, and thus he may con- tinue to be employed for endless ages ; forming new systems of beings to adore him ; and trans- 48 GEOGRAPHY OF THE HEAVENS. planting beings already formed into happier regions, who will continue to rise higher and higher in their enjoyments, and go on to contemplate system after system through the boundless universe. LA PLACE says : " As to those stars which sud- denly shine forth with a very vivid light, and then immediately disappear, it is extremely probable that great conflagrations, produced by extraordinary causes, take place on their surface. This conject- ure, is confirmed by their change of color, which is analogous to that presented to us on the earth by those bodies which are set on fire and then gra- dually extinguished." The late eminent Dr. Good also observes that " Worlds and systems of worlds are not only perpet- ually creating, but also perpetually disappearing. It is an extraordinary fact, that within the period of the last century, not less than thirteen stars, in different constellations, seem to have totally perish- ed, and ten new ones to have been created. In many instances it is unquestionable, .that the stars themselves, the supposed habitation of other kinds or orders of intelligent beings, together with the dif- ferent planets by which it is probable they were surrounded, have utterly vanished, and the spots which they occupied in the heavens, have become blanks ! What has befallen other systems, will assuredly befall our own. Of the time and the manner we know nothing, but the fact is incontro- vertible ; it is foretold by revelation ; it is inscribed in the heavens ; it is felt through the earth. Such is the awful and daily text; what then ought to be the comment ?" The great and good Beza, falling in with the superstition of his age, attempted to prove that this was a comet, or the same luminous appearance which conducted the magi, or wise men of the East, CONSTELLATION OF CASSIOPEIA. 49 into Palestine, at the birth of our Saviour, and that it now appeared to announce his second coming ! About 6 N. W. of Caph; the telescope reveals To us a grand nebula of small stars, apparently compressed into one mass, or single blaze of light, with a great number of loose stars surrounding it. TELESCOPIC OBJECTS. A LARGE AJTD LOOSE CLUSTER. A. R. = h. 18m. 10 s. Dec. = -j- 70 30, CONSTELLATION OF PISCES. 59 and so of the rest. Of those who imagine that the twelve constellations of the Zodiac refer to the twelve tribes of Israel, some ascribe Aries to the tribe of Simeon, and others, to Gad. During the campaigns of the French army in Egypt, General Dessaix discovered among the ruins at Dendera, near the banks of the Nile, the great templ6 supposed by some to have been dedicated to Isis, the female deity of the Egyptians, who believed that the rising of the Nile was occasioned by the tears which she continually shed for the loss of her brother Osiris, who was murdered by Typhon. Others suppose this edifice was erected for astronomical purposes, from the circumstance that two Zodiacs were discovered drawn upon the ceiling, on opposite sides. On both these Zodiacs the equinoctial points are in Leo, and not in Aries ; from which it has been concluded, by those who pertinaciously endeavor to array the arguments of science against the chronology of the Bible and the validity of the Mosaic account, that these Zodiacs were constructed when the sun emered the sign Leo, which must have been 9720 years ago, or 4000 years before the inspired account of the creation. The infidel writers in France and Germany, make it io,000 years before. But we may " set to our seal," that whatever is true in fact and correct in inference on this subject will be found, in the end, riot only consistent with the Mosaic record, but with the common meaning of the expressions it uses. The discovery of Champollion has put this question for ever at rest ; and M. Latronne, a most learned antiquary, has very satisfactorily de- monstrated that these Egyptian Zodiacs are merely the horoscopes of distinguished personages, or the precise situation of the heavenly bodies in the Zodiac at their nativity. The idea that such was their purpose and origin, first suggested itself to this gentleman on finding, in the box of a mummy, a similar Zodiac, with such inscriptions and characters as determined it to be the horoscope of the deceased person. Of all the discoveries of the antiquary among the relics of ancient Greece, the ruins of Palmyra, the gigantic pyramids of Egypt, the temples of their gods, or the sepulchres of their kings, scarcely one so aroused and riveted the curiosity of the learned, as did the discovery of Champollion the younger, which deciphers the hieroglyphics of ancient Egypt. The potency of this invaluable discovery has already been signally manifested in settling a formidable controversy between the champions of infidelity and those who maintain the Bible account of the creation. It has been shown that the constellation Pisces, since the days of Hip- parchus, has come, by reason of the annual precession, to occupy the same apparent place in the heavens that Aries did two thousand years ago. The Christian astronomer and the infidel are perfectly agreed as to the fact, and the amount of this yearly gain in the apparent motion of the stars. They both believe, and both can demonstrate, that the fixed stars have gone forward in the Zodiac, about 50" of a degree in every revolution of the heavens since the creation ; so that were the world to light upon any authentic inscription or record of past ages, which should give the true position or longitude of any particular star at that time, it would be easy tp fix an unquestionable date to such a record. Accord- 60 GEOGRAPHY OF THE HEAVENS. ingly, when the famous " Egyptian Zodiacs," which were sculptured on the walls of the temple at Dendera, were brought away en masse, and exhibited in the Louvre at Paris, they enkindled a more exciting interest in the thousands who saw them, than ever did the entrance of Napoleon. M Educated men of every order, and those who had the vanity to think themselves such," says the commentator of Champollion, " rushed to be- hold the Zodiacs. These Zodiacs were immediately published and com- mented upon, with more or less good faith and decorum. Science struck out into systems very bold ; and the spirit of infidelity, seizing upon the discovery, flattered itself with the hope of drawing from thence new sup- port. It was unjustifiably taken for granted, that the ruins of Egypt furnished astronomy with monuments, containing observations that ex- hibited the state of the heavens in the most remote periods. Starting with this assumption, a pretense was made of demonstrating, by means of calculations received as infallible, that the celestial appearances assign- ed to these monuments extended back from forty to sixty-five centuries ; that the Zodiacal system to which they must belong, dated back fifteen thousand years, and must reach far beyond the limits assigned by Moses to the existence of the world." Among those who stood forth more or less bold as the adversaries of revelation, the most prominent was M. Dupuis, the famous author of Uorigine de tous les Cultes. The infidelity of Dupuis was spread about by means of pamphlets, and the advocates of the Mosaic account were scandalized " until a new Alexander arose to cut the Gordian knot, which men had vainly sought to untie. This was Champollion the younger, armed with his discovery." ^ The hieroglyphics now speak a language that all can understand, and no * one gainsay. " The Egyptian Zodiacs, then," says Latronne, " relate in no respect to astronomy, but to the idle phantasies of judicial astrology, as connected with the destinies of the emperors who made or completed them." TELESCOPIC OBJECTS. A CLOSE DOUBLE STAR. A. R. = 1 h. 41 m. 19 s. Dec. = -j- 210 28' 7". On the horn of Aries. A 6, yellow. B 8, blue. Discovered by Herschel. Pos. 1720 26' Dist. 3".378 Epoch 1823.98 Struve. 169 54 2.400 1836.11 Smyth. y ARIETIS. A. R. = 1 h. 44 m. 45 s. Dec. =-f- 18 30' 5". In the lower bend of the Ram's horn. A 4, B 5. This is the first double star ever detected. Less than one hundred years have elapsed, and now they are numbered by thousands. Discovered by Dr. Hook 1764. Madler thinks motion is probable. Pos. 183 55' Dist. 10".172 Epoch 1779.63 Herschel. 179 30 8 .957 1831.79 Strive. 178 20 8 .819 1841.78 Madler. 175 37 9 .184 1847.65 MitcheL If we are to receive these observations as conclusive of periodic revolu- CONSTELLATION OF PISCES. 61 tion, the mighty year of these two suns cannot fall much short of four thousand of our years. A ROUND NEBULA. A. R. = 1 h. 50 m. 34 s. Dec. = -j- igo 13' 6". Following y on the neck of Aries. It is quite large but faint. A QUADRUPLE STAR A. R. = 1 h. 50 m. 43 s. Dec. =-J- 20 16' 7". Under the ear of Aries. A 6, B 15, C 10, D 9 magnitude. Measures of A and B only are given. The other distances are great. A to B Pos. = 530 32' Dist. 2". 370 Epoch 1832.42 Struve. 10 ARIETIS. A. R. = 1 h. 54 m. 35 s. Dec. = -f- 25 09' 7". Over the head of the Ram. A 6, B 8$. Discovered by Struve. Pos. 250 ir Dist. 1".98 Epoch 1833.05 Struve. ir ARIETIS. A. R. == 2 h. 40 m. 22 s. Dec. -f 16 47' 8". On the haunch of Aries. A beautiful triple set. A 5, B 8, C 11 magnitude. Discovered by Sir W. Herschel, October 1782. ARIETIS. A. R. = 20 h. 50m. 04s. Dec. = -f- 20O 41' 08"- A very close double star at the root of the tail of Aries. A 5, B 6^. Discovered by Struve, and reckoned by him as among his closest, and marked "pervicinse." It was one of the first tests employed after the erection of the Cincinnati Refractor, and so easily separated as to excite the suspicion that the distance between the components has been in- creasing. This is confirmed by the following measures. Pos. 1880 50' Dist. 0".547 Epoch 1830.16 Struve. 196 11 .764 1841.87 Mudler. 32 ARIETIS.-^A. R. = 2 h. 56 m. 05 s. Dec. = -f- 24O 37' 07". A triple set between the tail of Aries and the Fly. A 6, B 7, C 15, mag. Discovered by Struve. A to B Pos. 2660 34' 08" Dist. 0".45 Epoch 1841.87 Mudler. A to C 355 00 00 5 .00 1835.88 Smyth. A CLOSE DOUBLE STAB. A. R. = 3 h. 1 4 m. 06 s. Dec. = -\- 20<> 23' 07". Following the tail of Aries. A 8, B 9, mag. Discovered by Struve. Pos. 930 42' Dist. 0".75 Epoch 1827.16 Struve. 62 GEOGRAPHY OF THE HEAVENS. DIRECTIONS FOR TRACING THE CONSTELLATIONS ON MAP NO. IV. CETUS THE WHALE. PART OF ERIDANUS THE RIVER Po. Favorably situated for examination in October , Novem- ber , December, and January. THE WHALE. As the whale is the chief monster of the deep. and the largest of the aquatic race, so is it the largest constellation in the heavens. It occupies a space of 50 in length, E. and W., with a mean breadth of 20 from N. to S. It is situated below Aries and the Triangles, with a mean declination of 12 S. It is represented as making its way to the east, with its body below, and its head elevated above the equinoctial; and is six weeks in passing the meridian. Its tail comes to the meridian on the 10th of November, and its head leaves it on the 22d of December. This constellation contains ninety-seven stars ; three of the 2d magnitude, nine of the 3d, and seve- ral of the 4th. The head of Cetus may be readily distinguished, about 20 S. E. of Aries, by means of five remarkable stars, 4 and 5 apart, and so situated as to form a regular pentagon. The brightest of these is Menkar, a Ceti, of the 2d mag- nitude, in the nose of the Whale. It occupies the S. E. angle of the figure. It is 3j N. of the equinoc- tial, and 15 E. of El Rischa,a Piscium, in the bight of the cord between the Two Fishes. It is directly 37 S. of Algol, and nearly in the same direction from the Fly. It makes an equilateral triangle with Arietis and the Pleiades, being distant from CONSTELLATION OF CETUS. 63 each about 23 S., and may otherwise be known by a star of the 3d magnitude in the mouth', 3 W. of it, called y, placed in the south middle angle of the pentagon. v Is a star of the 4th magnitude, 4 N. W. of y, and these two constitute the S. W. side of the pen- tagon in the head of the Whale, and the N. E. side of a similar oblong figure in the neck. Three degrees S. S. W. of y, is another star of the 4th magnitude, in the lower jaw, marked 6, con- stituting the east side of the oblong pentagon ; and 6 S. W. of this, is a noted star in the neck of the Whale, called Mira, marked o, or the " wonderful star of 1596," which forms the S. E. side. This variable star was first noticed as such by Fabricius, on the 13th of August, 1596. It changes from a star of the 2d magnitude so as to become invisible once in 334 days, or about seven times in six years. Her- schel makes its period 331 days, 10 hours, and 19 minutes ; while Hevelius assures us that it once disappeared for four years ; so that its true period, perhaps, has not been satisfactorily determined. The whole number of stars ascertained to be variable, amounts to only 15 ; while those which are suspected to be variable amount to 37. Mira is 7 S. S. E. of a Piscium, in the bend or knot of the ribbon which connects the Two Fishes. Ten degrees S. of Mira, are four small stars, in the breast and paws, about 3 apart, which form a square, the brightest being on the east. Ten de- grees S. W. of Mira, is a star of the 3d magnitude in the heart, called Eaten Kaitos, Ceti, which makes a scalene triangle with two other stars of the same magnitude 7 and 10 west of it ; also, an equilateral triangle with Mira and the easternmost one in the square. A great number of geometrical figures may be formed from the stars in this, and in most of the other constellations, merely by reference to the 64 GEOGRAPHY OF THE HEAVENS. maps ; but it is better that the student should exercise his own ingenuity in this way with reference to the stars themselves, for whr n once he has constructed a group into any letter or figure of his own invention, he never will forget it The teacher should therefore require his class to commit to writing the result of their own observations upon the relative position, magnitude and figures of the principal stars in each constellation. One evening's exer- cise in this way will disclose to the student a surprising multitude of crosses, squares, triangles, arcs and letters, by which he will be better able to identify and remember them, than by any instructions that could be given. For example : o and in the Whale, about 10 apart, make up the S. E. or shorter side of an irregular square, with A in the node of the Ribbon, and another star in the Whale as far to the right of , as a is above o. Again, There are three stars of equal magnitude, forming a straight line W. of Baten; from which, to the middle star is 10, thence to the W. one 12; and 8 or 9 S. of this line, in a triangular direction, is a bright star of the second magnitude in the coil of the tail, called Diphda, or /. TELESCOPIC OBJECTS. 12 CETI. A. R. = Oh. 21 m. 53s. Dec. = 4 50' 06". A difficult double star, between the Whale's tail and the Southern Fish. A 6, yellow ; B 15, blue. Position and distance estimated as follows, in the Bedford Catalogue : Pos. 1800 56' Dist. 6".5 Epoch 1837.89. A LONG NARROW NEBULA. A. R. = h. 39 m. 45 s. Decl. = 26 10'. Near the boundary of the Apparatus Sculptoris. Discovered by Miss Herschel, in 1783. 42 CETI. A, R. = 1 h. llm. 38 s. Dec. = lo 21'. A close double star, between the whale's back and the band of Pisces. A 6, B 8 mag. Discovered by Striive and marked among his " Vicinae " stars. Pos. = 334 30' Dist. I'M 77 Ep. 1836.91 Striive. 61 CETI. A. R. = 1 h. 55 m. 37 s. Dec. = lo 06' 5". A double star on the back of the head of Cetus. A 7, B 8 mag. Dis- covered by Striive, who reports the following measures. Pos. = 2500 00' Dist. 4".78. Epoch 1832.36. o CETI. MIRA. A. R. = 2 h. 11 m. 16 s. Dec. = 30 42' 3". A remarkable variable star, with a distant companion, on the middle of the whale's neck. It is the first of these wonderful objects ever discover- ed, and was noticed by David Fabricius as early as 1596. It becomes as bright as the second magnitude, and then decreases to invisibility. Her- schel estimates its period at 33 1 days 1 hours 1 9 minutes. Its maxi- mum brilliancy is attained about the first of October at this time. The color of this star is also said to vary with the magnitude. CONSTELLATION OF CETUS. 65 A PLANETARY NEBULA. A. R. = 2 h 19 m. 25 s. Dec. = 1 51' 6". In the middle of the whale's neck. Discovered by Herschel, 1T85. v CETI. A. R. = 2 h. 27 m. 29 s. Dec. = -}- 4 53' 5". A double star in the whale's eye. A 4|, yellow, B 1ft, blue. This is one of Struve's " difficiles ". He reports the following measures : Pos. 83030' Dist7".725 Ep. 1831.92. 84 CETI. A. R. = 2 h. 33 m. 02 s. Dec. = 1 22' 7". A difficult object like the preceding, on the whale's under jaw. Striive, its discoverer furnishes these measures : Pos. 3340 37' Dist. 4".855 Ep. 1831.90. A ROUKD NEBULA A. R. = 2 h. 34m. 30s. Dec. = 41' 01". On the Whale's lower jaw. Examined by Herschel, and placed in the 910th order of distances; that is, 910 times more remote than the fixed stars of the first magnitude. Discovered by Messier. y CETI. A. R. = 2 h. 35 m. 01". Decl. = -f 2O 33' 05". A beautiful close double star, in the Whale's mouth. The Bedford Cata- logue regards the < fixity" of the components as established*; while Midler thinks an increasing motion certain, with a period of about 569 years. The following measures are reported : Pos. = 283 12' Dist. 2".835 Epoch 1825 42 Strdve. 287 06 2 .680 1833.36 293 37 2 .946 1841.14 Mudler. AN OVAL NEBULA. A. R. = 2 h. 38 m 08 s. Decl. = 8 15' 1". On the breast of the Whale. " It is pale, though distinct, and brightens at the center." Discovered by Herschel, 1785. 94 CKTI. A. R. = 3 h. 04 m. 38 s. Decl. = 1 47' 09". A difficult double star, in the top of the Whale's tongue. A 5^, B 16, mag. Discovered by Sir John Herschel. ;:-* F* GEOGRAPHY OF THE HEAVENS. DIRECTIONS FOR TRACING THE CONSTELLATIONS ON MAP NO. V. TAURUS THE BULL. ORION. PART OF ERIDANUS THE RIVER Po. Favorably situated for examination in December , Ja- , February and March. TAURUS. . THE BULL is represented in an attitude of rage, as if about to plunge at Orion, who seems to invite the onset by provocations of assault and defiance. Only the head and shoulders of the animal are to be seen ; but these are so distinctly marked that they cannot be mistaken. Taurus is now the se- cond sign and third constellation of the zodiac ; but anterior to the time of Abraham, or more than 4000 years ago, the vernal equinox took place, and the year opened when the sun was in Taurus ; and the Bull, for the space of 2000 years, was the prince and leader of the celestial host. The Ram suc- ceeded next, and now the Fishes lead the year. The head of Taurus sets with the sun about the last of May, when the opposite constellation, the Scorpion, is seen to rise in the S. E. It is situated between Perseus and Auriga on the north, Gemini on the east, Orion and Eridanus on the south, and Aries on the west, having a mean declination of 16 north. It contains 141 visible stars, including two re- markable clusters, called the PLEIADES and HYADES. The first is now on the shoulder, and the latter in the face of the Bull. The Pleiades, according to fable, were the seven daughters of Atlas and the nymph Pleione, who CONSTELLATION OF TAURUS. 67 were turned into stars, with their sisters the Hyades, on account of their amiable virtues and mutual affection. Thus we everywhere find that the ancients, with all their barbarism and idolatry, entertained the belief that unblemished virtue and a merito- rious life would meet their reward in the sky. Thus Virgil represents Magnus Apollo as bending from the sky to address the youth lulus : " Macte nova virtute puer : sic itur ad astra ; Diis genite, et geniture Deos." "Go on, spotless boy, in the paths of virtue ; it is the way to the stars ; offspring of the gods thyself so shalt thou become the father of gods." Our disgust at their superstitions may be in some measure mitigated, by seriously reflecting, that had some of these personages lived in our day, they had been ornaments in the Christian church, and models of social virtue. The names of the Pleiades are Alcyone, Merope, Maia, Electra, Tayeta, Sterope and Celeno. Merope was the only one who married a mortal, and on that account her star is dim among her sisters. Although but six of these are visible to the naked eye, yet Dr. Hook informs us that, with a twelve feet telescope, he saw 78 stars ; and Rheita affirms that he counted 200 stars in this small cluster. The most ancient authors, such as Homer, Attains, and Geminus, counted only six Pleiades ; but Simonides, Varro. Pliny, Aratus, Hip- parchus, and Ptolemy, reckon them seven in number ; and it was as- serted, that the seventh had been seen before the burning of Troy ; but this difference might arise from the difference in distinguishing them with the naked eye. The Pleiades are so called from the Greek word, TtXfftv, pleein, to sail; because, at this season of the year, they were considered *' the star of the ocean" to the benighted mariner. Alcyone, of the 3d mag- nitude, being the brightest star in this cluster, is sometimes called the light of the Pleiades. The other five are principally of the 4th and 5th magnitudes. The Pleiades, or as they are more familiarly termed, the seven stars, come to the meridian 10 minutes before 9 o'clock, on the evening of the 1st of January, and may serve, in place of the sun, to 68 GEOGRAPHY OF THE HEAVENS. v^! indicate the time, and as a guide to the surrounding stars. According to Hesiod, who wrote about 900 years before the birth of our Saviour, the heliacal rising of the Pleiades took place on the llth of May, about the time of harvest. " When, Atlas-born, the Pleiad stars arise Before the sun above the dawning skies, 'Tis time to reap ; and when they sink below The morn-illumin'd west, 'tis time to sow." Thus, in all ages, have the stars been observed by the husbandman, for " signs and for seasons." Pliny says that Thales, the Miletan astronomer, determined the cos- mical setting of the Pleiades to be 25 days after the autumnal equinox. This would make a difference between the setting at that time and the present, of 35 days, and as a day answers to about 59' of the ecliptic, these days will make 34 25'. This, divided by the annual precession (50f ), will give 2465 years since the time of Thales. Thus does astronomy become the parent of chronology. If it be borne in mind that the stars uniformly rise, come to the meri- dian, and set about four minutes earlier every succeeding night, it will IK? very easy to determine at what time the seven stars pass the meridian on any night subsequent or antecedent to the 1st of January. For exam- ple : at what time will the seven stars culminate on the 5th of January "! . Multiply the five days by four, and take the result from the time they culminate on the 1st, and it will give thirty minutes after eight o'clock in the evening. The Pleiades are also sometimes called Vergilice, or the " Virgins of spring ; " because the sun enters this cluster in the " season of blossoms," about the 18th of May. He who made them alludes to this circumstance when he demands of Job : " Canst thou bind the sweet influences of the Pleiades," &c. [Job xxxviii, 31.] The Syrian name of the Pleiades is Succoth, or Succofh-Benotk, de- rived from a Chaldaic word, which signifies " to speculate, to observe," and the "Men of Succoth" (2 Kings xvii, 30), have been thence considered observers of the stars. The Hyades are situated 11 S. E. of the Pleiades, in the face of the Bull, and may be readily dis- tinguished by means of five stars so placed as to form the letter V. The most brilliant star is on CONSTELLATION OF TAURUS. 69 the left, in the top of the letter, and called Aldeba- ran, a Tauri, from which the moon's distance is computed. " A star of the first magnitude illumes His radiant head ; and of the second rank, Another beams not far remote." Aldebaran is of Arabic origin, and takes its name from two words which signify, " He went before, or led the way " alluding to that period in the history of astronomy when this star led up the starry host from the vernal equinox. It comes to the meridian at nine o'clock on the 10th of January, or 48 minutes after Alcyone, ? Tauri, on the 1st. When Aries is about 27 high, Aldebaran is just rising in the east. So MANILIUS : " Thus when the Ram hath doubled ten degrees, And join'd seven more, then rise the Hyades." A line 15 E. N. E. of Aldebaran will point out a bright star of the 2d magnitude in the extremity of the northern horn, marked j3 or El Nath ; (this star is also in the foot of Auriga, and is common to both constellations.) From j3 in the northern horn, to in the tip of the southern horn, it is 8, in a southerly direction. This star forms a right angle with a and p. /3 and . both, in the button of the horns, are in a line nearly north and south, 8 apart, with the brightest on the north. That very bright star 17 N. of j3, is Capella a, in the constel- lation Auriga. This map contains the most brilliant, and on all accounts, the most interesting portions of the heavens. According to the investigations of Striive, this region is nearer to our sun and system than any other portion of the celestial sphere, as will be more fully developed hereafter. Besides this, Alcy- one is regarded as the great center of the millions 70 GEOGRAPHY OF THE HEAVENS. of stars clustered together and forming the Milky Way. This region, on account of its splendor, arid the remarkable configurations of its stars, forms an ad- mirable point in beginning the study of the heavens. TELESCOPIC OBJECTS. 7 TAURI. A. R. = 3 h. 24 m. 58 s. Dec. = -f- 23 55' 4". A triple star on the back of Taurus. A 6, B 6, C 11 magnitude. Discovered by Struve, and two of the components are among his " vicinessemae,'' or close stars. From his measures, compared with Mildler's, a retrograde movement in A and B seems to be certain. A toB Pos. 2710 00' Dist. = 0".G3 Epoch 1827. 16 Struve. 264 35 .55 1841.80 Midler. A -f- B to C Pos. 630 36 Dist. 22".25 Epoch 1827.16 Struve. 2 60 18 22 .50 1841.80 Mudler. The period of A about B, is probably about 580 or 590 years. 30 TAURI. A. R. = 3 h. 39 m. 30 s. Dec. = -}- 1 6 38' 8". A delicate double star on the left shoulder-blade of Taurus. A 6, " pale emerald." B 10, " purple." Discovered by Herschel. Pos. 58 46' Dist. 9".867 Epoch 1824.98 Struve. A DOUBLE STAR. A. R. = 3 h. 51 m. 27 s. Dec. = 22 44' 7". In the neck of Taurus, between the Pleiades and Hyades. A 7, B 8 magnitude. A distant companion of the 12 magnitude. Discovered by Struve. Pos. 127 4 r Dist 7". 208 Epoch 1823.98 South. 80 TAURI. A. R. = 4 h.21 m.Ol s. Dec. = -f- 15O 17'. A close double star on the Bull's face, 1^ south west of Aldebaran. A 6, B8$. Pos. 120 5f>' Dist. 1".74 Epoch 1831.18 Struve. A CLOSE DOUBLE STAR. A. R. = 5 h. 7 m. 23 s. Dec. -f- 18 15' 3". On the southern horn of Taurus. A 8, B 8. Discovered by Strive. Pos. 171 13' Dist. 2".327 Epoch 1830.53 Struve. A DOUBLE STAR. A. R. = 5 h. 8 m. 03 s. Dec. = -{- 19 57' 2". In the middle of the southern horn of Taurus. A 8, B 11 magnitude. Discovered by Struve. Pos. 147 33' Dist. 10".547 Epoch 1828.19 Struve. 118 TAURI. A. R. = 5 h. 19 m. 25 s. Dec. = -f. 25 00' 8". Between the tips of the Bull's horns. A 7, B 74. Pos. I960 46' Dist. 4".89 Epoch 1829.63 Struve. CONSTELLATION OF TAURUS. 71 A LARGE NEBULA. A. R. = 5 h. 24 m. 51 s. Decl. = -j- 21O 54' 02". One degree N. W. of Tauri, on the tip of the Bull's southern horn. Discovered by Messier, 1758, and is No. 1 of his great catalogue. It was accidentally picked up white observing the comet of that year, and induced Messier to commence a search for such objects. It is resolved with difficulty by the best instruments, and Herschel reckons its profun- dity of the 980th order that is, 980 times more remote than stars of the lirst magnitude. H TAURI. A. R. = 3 h. 37 m.- 59 s. Decl. = -f- 23O 36' 3". Al- cyone, the principal star in the Pleiades, a small cluster visible to the eye in the neck of Taurus. This little group has ever been remarkable, but recently a tenfold interest has been given to it by the announcement of Dr. Miidler of Dorpat, Russia, that its chief star, Alcyone, is the central sun of our astral system. It is absolutely certain that the law of gravi- tation extends to the fixed stars, as is abundantly shown by the orbitual revolution of the double stars, whose periods and places have been com- puted and predicted by the application of this law. This being certain, in the mighty group of millions of stars with which our own sun is associated, there must be a center of gravity , and it then remains to determine whether this point is filled by a ponderous globe, of vast dimensions, and bearing the same relation in point of mag- nitude to the millions of suns by which it is surrounded, as our sun does to the planets, satellites, and comets by which it is encircled. Analogy, in the solar 'system, taught the existence of such a ponderous mass, but this analogy was broken in the revolving stars ; in which it often occurs that the components are nearly equal in magnitude, moving round a common center of gravity. Again, in examining the heavens, such a mighty preponderating body would be detected by the swifter proper motion of the stars in its vicinity. After a laborious search, Miidler reached the conclusion that no such vast globe existed, and that the center of gravity, probably vacant, could only t>e found by a severe examination of the proper motions of the fixed stars. By a beautiful train of reasoning and closely conducted research, he finally reached the conclusion that Alcyone, in the Pleiades, now holds the high rank of central sun , but that, in the course of ages, by the perpetual changes constantly going on among the components of our astral system, this rank may pass to some other star. He computes roughly the distance of Alcyone, and reckons it to be so great, that light, flying with a velocity of twelve millions of miles a minute, cannot reach us from that star hi less than 537 years. He further computes roughly, that our sun revolves about Alcyone in a period of 18,200,000, in an orbit inclined to the ecliptic under an angle of 84 00'. Should this wonderful theory be confirmed, the proper motions of the fixed stars assume a new and increased interest (See Midler's Paper, "Central Sun" Mitchel's Sidereal Messenger, Nos. 4 and 5, Vol. I.) A NEBULOUS STAR. A. R. = 3 h. 59 m. 06 s. Decl. -|- 30 20 05". Over the neck of Taurus. This object was discovered by th elder Herschel, and was the final link in that long chain of observation 72 GEOGRAPHY OF THE HEAVENS. which led to the adoption of the nebular theory." The star is perfectly in the center of the nebulous atmosphere which surrounds it, and Her- schel argues the nebulosity of this seeming atmosphere from the fact that, in case each shining point is a star, what must be the magnitude of the central orb, which exceeds them all in the enormous ratio of millions to one. These nebulous stars are certainly most wonderful objects, and deserve the most rigid scrutiny. % TATJHI A. R. == 4h. 12 m. 51 s. Decl. = -\- 25 14' 07". A double star at the back of the Bull's ear. A 6, B 8, mag. Pos. 25QQO' Dist. 19".3 Epoch 1831.91 Smyth. ORION. WHOEVER looks up to this constellation and learns its name, will never forget it. It is too beautifully splendid to need a description. When it is on the meridian, there is then above the horizon the most magnificent view of the celestial bodies that the starry firmament affords ; and it is visible to all the habitable world, because the equinoctial passes through the middle of the constellation. It is rep- resented on celestial maps by the figure of a man in the attitude of assaulting a Bull, with a sword in his belt, a huge club in his right hand, and the skin of a lion in his left, to serve for a shield. Manilius, a Latin poet, who composed five books on astronomy, a short time before the birth of our Saviour, thus describes its appearance : " First next the Twins, see great Orion rise, His arms extended stretch o'er half the skies ; His stride as large, and with a steady pace He marches on, and measures a vast space; On each broad shoulder a bright star display'd, And three obliquely grace his hanging blade. In his vast head, immers'd in boundless spheres, Three stars, less bright, but yet as great, he bears, But farther off removed, their splendor's lost ; Thus grac'd and arm'd, he leads the starry host. " The center of the constellation is midway between the poles of the heavens and directly over the equa- CONSTELLATION OF ORION. 73 tor. It is also about 8 W. of the solstitial colure, and comes to the meridian about the 23d of Janu- ary. The whole number of visible stars in this constellation is seventy-eight ; of which two are of the 1st magnitude, four of the 2d, three of the 3d, and fifteen of the 4th. Those four brilliant stars in the form of a long square or parallelogram, intersected in the middle by the " Three Stars," or " Ell and Yard," about 25 S. of the Bull's horns, form the outline of Orion. The two upper stars in the parallelogram are about 15 N. of the two lower ones ; and, being placed on each shoulder, may be called the epaulets of Orion. The brightest of the two lower ones is in the left foot, on the W., and the other, which is the least brilliant of the four, in the right knee. To be more particular : Bellatrix, y Orionis, is a star of the 2d magnitude on the W. shoulder ; Betelguese, a Orionis, is a star of the 1st magnitude, ?i E. of Bellatrix, on the E. shoulder. It is brighter than Bellatrix, and lies a little farther towards the north ; and comes to the meridian thirty minutes after it, on the 21&t of January. These two form the upper end of the parallelogram. Rigel, /3 Orionis, is a splendid star of the 1st mag- nitude, in the left foot, on the W. and 15 S. of Bellatrix. Saiph, is a star of the 3d magnitude, in the end of the sword scabbard, 8^ E. of Rigel. These two form the lower end of the parallelogram. First in rank The martial star upon his shoulder flames : A rival star illuminates his foot ; And on his girdle beams a luminary Which, in vicinity of other stars, Might claim the proudest honors." There is a little triangle of three small stars in the head of Orion, which forms a larger triangle with the two in his shoulders. In the middle of the G 74 GEOGRAPHY OF THE HEAVENS. parallelogram are three stars of the 2d magnitude, in the belt of Orion, that form a straight line about 3 in length from N. W. to S. E. They are usually distinguished by the name of the Three Stars, be- cause there are no other stars in the heavens that exactly resemble them in position and brightness. They are sometimes denominated the Three Kings, because they point out the Hyades and Pleiades on one side, and Sirius, or the Dog-star on the other. In Job they are called the Bands of Orion; while the ancient husbandmen called them Jacob's rod, and some times the Rake. The University of Leipsic, in 1807. gave them the name of Napoleon. But the more common appellation for them, including those in the sword, is the Ell and Yard. They derive the latter name from the circumstance that the line which unites the " three stars " in the belt measures just 3 in length, and is divided by the central star into two equal parts, like a yard-stick ; thus serving as a graduated standard for measuring the distances of stars from each other. When therefore any star is described as being so many degrees from another, in order to determine the distance, it is recommend- ed to apply this rule. It is necessary that the scholar should task his ingenuity only a few evenings in applying such a standard to the stars, before he will learn to judge of their relative distances with an accuracy that will seldom vary a "degree from the truth. The northernmost star in the belt, called Mintika, a, is less than J S. of the equinoctial, and when on the meridian, is almost exactly over the equator. It is on the meridian, the 24th of January. The " three stars " are situated about 8 W. of the solstitial colure, and uniformly pass the meridian one hour and fifty minutes after the seven stars. There is a row of stars of the 4th and 5th mag- nitudes, S. of the belt, running down obliquely to- wards Saiph, which forms the sword. This row is CONSTELLATION OF ORION. 75 also called the Ell, because it is once and a quarter the length of the Yard or belt. A very little way below Thabit, Orionis, in the sword, there is a nebulous appearance, the most remarkable one in the heavens. With a good tele- scope an apparent opening is discovered, through which, as through a window> we seem to get a glimpse of other heavens, and brighter regions beyond. As the telescope extends our knowledge of the stars and greatly in- creases their visible number, we behold hundreds and thousands, which, but for this almost divine improvement of our vision, had forever remain- ed, unseen by us, in an unfathomable void. A star in Orion's sword, which appears single to the unassisted vision, is multiplied into six by the telescope ; and another into twelve. Galileo found eighty in the belt, twenty-one in a nebulous star in the head, and about five hundred in another part of Orion, within the compass of one or two degrees. Dr. Hook saw seventy-eight stars in the Pleiades, and Rheita with a better telescope, saw about two hundred in the same cluster and more than two thousand in Orion. About 9 W. of Bellatrix, y , are eight stars, chiefly of the 4th magnitude, in a curved line running N. and S. with the concavity towards Orion ; these point out the skin of the lion in his left hand. Of Orion, on the whole, we may remark with Eudosia: " He who admires not, to the stars is blind."' As the constellation Orion, which rises at noon about the 9th day of March, and sets at noon about the 21st of June, is generally supposed to be accompanied, at its rising, with great rains and storms, it became ex- tremely terrible to mariners, in the early adventures of navigation. Virgil, Ovid, and Horace, with some of the Greek poets, make mention of this. Thus Eneas accounts for the storm which cast him on the African coast on his way to Italy : " To that blest shore we steer'd our destined way, When sudden, dire Orion rous'd the sea : All charg'd with tempests rose the baleful star, And on our navy pour'd his wat'ry war." To induce him to delay his departure, Dido's sister advises her to " Tell him, that, charg'd with deluges of rain, Orion rages on the wintry main." 76 GEOGRAPHY OF THE HEAVENS. The name of this constellation is mentioned in the books of Job and Amos, and in Homer. The inspired prophet, penetrated like the psalmist of Israel, with the omniscience and power displayed in the celestial glories, utters this sublime injunction : " Seek Him that maketh the seven stars and Orion, and turneth the shadow of death into morning." Job also, with profound veneration, adores His awfol majesty who " commandeth the sun and sealeth up the stars ; who alone spreadeth out the heavens, and maketh Arcturus, Orion, and Pleiades, and the chambers of the south : " And in another place, the Almighty demands of him ' Knowest thou the ordinances of heaven 1 Canst thou bind the sweet influences of the Pleiades, or loose the bands of Orion ; canst thou bring forth Mazzaroth. in his season, or canst thou guide Arcturus with his sons 1 " Calmet supposes that Mazzaroth is here put for the whole order of celestial bodies in the Zodiac, which by their appointed revolutions, pro- duce the various seasons of the year, and the regular succession of day and night. Arcturus is the name of the principal star in Bootes, and is here put for the constellation itself. The expression, his sons, doubtless refers to Asterion and Chara, the two greyhounds, with which he seems to be pursuing the great bear around the .North pole. TELESCOPIC OBJECTS. 258 P. IV. ORTOXTS. A. R. = 4 h. 49m. 48s. Dec. = 4- 1 25' 04". A double star preceding Orion's right knee. A 8, B 9, mag. Discovered by Herschel. Pos. 1740 51' Dist. 2".00 Epoch 1782.85 Herschel. 179 54 2 .64 1832.09 Striive. ORIONIS. A. R. = 5 h. 04 m. 55 s. Dec. = -|- 2 39' 09". A double star between the right arm and thigh of Orion. A 5, B 8, the first orange, the second blue. Pos. 63 28' Dist. 7". 05 Epoch 1832.05 Striive. ORIOSIS. A. R. = 5 h. 6 m. 51 s. Dec. = 8O 23' 05". Ri- gel, a double star in the right foot of Orion. A 1 , " pale yellow," B 9, " sapphire blue." A third star has been recently added by artificial occultation, at the Cincinnati Observatory. It is of the 20th magnitude, and invisible without hiding the principal stars. The relative positions of the stars remain unchanged since their dis- covery, in 1781. Discovered by Herschel. Pos. 199 46' Dist. 9".14 Epoch 1831.53 Struve. 84 P. V. ORIOKIS. A. R, = 5 h. 16 m. 53 s. Dec. = -f- 1 46' 4". A close double star hi Orion's right side. A 8, B 10. The components are fixed. Discovered by Herschel. Pos. 323 13' Dist 2".61 Epoch 1831.81. 32 ORIOXIS. A. R. = 5 h. 22 m. 13 s: Dec = -f- 5O 49' 03". A close double star on the right shoulder of Orion. A 5, B 7, mag. A CONSTELLATION OF ORION. 77 parison of late measures with those of Herschel in 1780, indicates a slow retrograde motion, amounting to some 10 or 12 in half a century. Pos. 203 45' Dist. 1".04 Epoch 1830.96 Strive. 33 ORIOX rs. A. R. = 5 h 22 m, 5 1 s. Dec. = -f- 3 09' 9". A close double star on the right shoulder. A 6, B 8, mag. Pos. 25 35' Dist. 1".87 Epoch 1831.22 Struve. x ORIOX.S. A. R. = 5 h. 26 m. 19 s. Dec. = -f 9 49' 03". A double star in the ear of Orion. A 4, w " pale white," B 6, violet. No change has been detected. Discovered by Herschel, 1779. Pos. 40 32' Dist. 4".24 Epoch 1830.21 Struve. Q OHIO* is. A. R. = 5 h. 27 m. 25 s. Dec. 5 30'. A sextuple star in the great nebula in the sword scabbard of Orion. A 6, B 7, C 7, D 8, E 15, F 16, mag. For more than fifty years this object was regarded as only quadruple. After the mounting of the " Dorpat refrac- tor," Strive added a fifth star to the four already known ; and a few years since a sixth was discovered by Sir James South. It is not certain that any change has yet been detected among the components of this remarkable grpup. Pos. A B, 3110 14' Dist, 12".983 Epoch 1832.53 Struve. A C, 60 07 13 .467 1832.53 A D, 342 10 16 .780 1832.53 B E, 355 42 3 .860 1832.53 THE GREAT NEBULA iv OHIOX. A. R. = 5h. 27 m. 25 s. Dec. = 5 30'. This stupendous object is situated in the middle of the scabbard of Orion's sword. Discovered by Huygens, 1656. It has been an object of the greatest interest, to all astronomers, in consequence of its brilliancy and extraordinary magnitude. Sir William Herschel repeat- edly examined it with scrutiny with his forty feet refractor, but detected nothing like resolvability. Most accurate drawings were made by his son, without any suspicion that it was composed of a mass of stars. As Sir John Herschel remarked, the greater the power employed the more mysterious did the object appear. Dr. J. Lamont, of Munich, has exa- mined this nebula with great attention, and many years since affirmed that with the twelve inch refractor of the Munich Observatory, he caught glimpses of multitudes of point-like stars, crowding and producing the brighter parts of the nebula ; yet to this announcement little heed seems to have been given. On mounting the giant reflector of Lord Rosse, it was a matter of deep interest to learn the appearance of this nebula under the scrutiny of this magnificent instrument. More than one astronomer made the journey to the castle of Lord Rosse, to inspect this wonderful object. For a long time it resisted the full power of the greatest of all optical instruments, until at length Lord Rosse makes the following an- nouncement : " Castle Parsantown, March 19, 1846. " In accordance with my promise of communicating to you the result of our examination of Orion, I think I can safely say there can be but 78 GEOGRAPHY OF THE HEAVENS. little, if any doubt, as to the resolvability of the nebula. Since you left us, there was not a single night, when, in absence of the moon, the air was free enough to admit the use of more than half the magnifying power the speculum bears ; still, we could plainly see, that all about the trapezium is a mass of stars ; the rest of the nebula abounding in stars, and exhibiting the characteristics of resolvability strongly marked. " ROSSE." This announcement has been made the basis of an argument, by Dr. Nichol, to overthrow the nebular theory of the formation of the universe ; a theory which had derived much of its popularity from the powerful argument in its behalf made by the same gentleman, a short time before, iu his " Architecture of the Heavens." If Lord Rosse is quite sure of the resolution of the nebula, it but confirms the previous declaration of Dr. Lamont, and the nebular theory loses but little of its former strength by the removal of a prop already much shaken by the Munich Astronomer. Resolved or unresolved, this is certainly, under every aspect, one of the most sublime objects revealed by telescopic agency so vast that the mind fails, utterly, to grasp its mighty outlines. A s a starry system, it is so distant that the light which leaves it, to journey to our eyes, spends no less than 30,000 years in sweeping over the stupendous interval. As a nebula, it contains materials sufficient for the production of millions of suns and systems. View it as we may, its vastness, its magnificence, must exalt our ideas of the omnipotence of the Great Architect of the Heavens. Under the full power of the Cincinnati refractor, the deep contrast be- tween the brilliancy of the stars and nebulosity, and the jet black heavens on which they are seen, is one of the most beautiful sights in the heavens. Whether this blackness be the effect of mere contrast, or an intrinsic darkness, occasioned by the absence of all light, it is difficult to determine. This is not a solitary instance of the phenomenon in question. I have ob- served the same in several other instances but in no case have I remark- ed such intense blackness in the heavens, as about this nebula. a- Oiuoyis. A. R. = 5 h. 30 m. 43 s. Dec, = 2 41' 8". A multiple star just below the belt of Orion, an excellent object for testing the light of telescopes. There are no less than ten stars counted as the components of this one. A 4, a U, B 8, C 7, D 8|, E 9, F 8, magnitudes. 34 HEHSCHEI, ORIONIS. A. R. = 5 h, 33 m. 21 s. Dec. = -f- 9 00' 2". A planetary nebula on Orion's neck. Discovered by Herschel, and described by his son as " a small pale, but distinct nebula, with a faint disc, rather oval, and perhaps a little mottled." 78 MKSSIER, ORIONIS. A. R. = 5 h. 38 m. 33 s. Dec. = -f 00' 7". " Two stars in a wispy nebula, just above Orion's hip." This is a remarkable object. Discovered by Messier in 1780. CONSTELLATION OF ORION. 79 52 ORIOXIS. A. R. = 5 h, 39 m 24 s. Dec. = -f- 6 23' 6". A close double star in Orion's left shoulder. A 6, B 6 magnitude. The position has never changed. Pos. 200 01 Dist. 1".75 Epoch 1831.23 Struve. E RID AN US . THE RIVER Po. This constellation meanders over a large and very irregular space in the heavens. It is not easy, nor scarcely desirable, to trace out all its windings among the stars. Its entire length is not less than 130; which, for the sake of a more easy reference, astronomers divide into two sections, the northern and the southern. That part of it which lies between Orion and the Whale, including the great bend about his paws, is distinguished by the name of the Northern stream ; the remainder of it is called the Southern stream. The Northern stream commences near Rigel (Map No. V), in the foot of Orion, and flows out westerly, in a serpentine course nearly 40, to the Whale (Map No. IV), where it suddenly makes a complete circuit and returns back nearly the same distance towards its source, but bending gradually down towards the south, when it again makes a similar circuit to the S. W. and finally disappears below the horizon. West of /3 Orionis (Map No V) there are five or six stars of the 3d and 4th magnitudes, arching up in a semicircular form, and marking the first bend of the northern stream. About 8 below these, or 19 W. of @>, is a bright star of the 2d magnitude, in the second bend of the northern stream, marked y. This star culminates thirteen minutes after the Pleiades, and one hour and a quarter before $. Passing y, and a smaller star west of it, there are four stars nearly in a row, which bring us to the breast of Cetus. 8 N. of y, is a small star named Kied, which is thought by some to be considerably nearer the earth than Sirius. Theemim, in the southern stream, is a star of the 3d magnitude, about 17- S. W. of the square in Lepus, and may be known by means of a smaller star. 1 above it. Achernar is a brilliant star of the 1 st magnitude, in the extremity of the southern stream ; but having 58 of S. declina- tion, can never be seen in this latitude. 80 GEOGRAPHY OF THE HEAVENS. The whole number of stars in this constellation is eighty-four; of which, one is of the 1st magnitude, one of the 2d, and eleven are of the 3d. Many of these cannot be pointed out by verbal description ; they must be traced from the map. TELESCOPIC OBJECTS. 98, P, IE, ERIDANI. A. R. = 3 h. 28 m. 35 s. Dec. = -j- 03' 7". A delicate double star, in the line joining a. Ceti and $ Orionis, at one-third their distance. A 6, yellow ; B 9, pale blue. Discovered by Herschel. Pos. 225 12' Dist. 5". 812 Epoch 1824.02 Struve. This object is between the Bull's chest and the northern branch of the River. 107 HERSCHEL I, ERIDAWT. A. R. = 3 h. 33 m. 02 s. Dec. = 19 04' 8". A white nebula between the two northern reaches of the River. Discovered by Herschel, and described as " pale but distinct, round and bright in the center." 32 ERIDANI. A. R. = 3 h. 46 m. 16 s. Dec. = 3 25' 9". A double star between the chest of Taurus and the River. A 5, yellow ; B 7, sea green. Discovered by Herschel. Pos. 3490 45' Dist. 6".75 Epoch 1825.00 Struve. 39 ERIDAXI. A. R. = 4 h. 06 m. 48 s. Dec. 10 39' 4". A double star in the north, following bend of the River. A 5, " full yellow ; " B 11, "deep blue.'* Discovered by Herschel. Pos. 1520 12' Dist. 6".28 Epoch 1833.14 Struve. 26 HERSCHEL IV, ERIDANI. A. R. = 4 h. 06 m. 50 s. Dec, = 13 09' 1" A planetary nebula under the N. F. bend of the River. Discovered by Herschel, in 1784, who saw it slightly elliptical, and thought it might be a globular cluster at an immense distance. CONSTELLATION OF AURIGA. 81 DIRECTIONS FOR TRACING THE CONSTELLATIONS ON MAP NO. VI. AURIGA THE WAGONER. Favorably situated for examination in December, January, February and March. AURIGA. THE Charioteer, called also the Wagoner, is rep- resented on the celestial map by the figure of a man in a reclining posture, resting one knee upon the horn of Taurus, with a goat and her kids in his right hand, and a bridle in his left. It is situated N. of Taurus and Orion, between Perseus on the W. and the Lynx on the E. Its mean declination is 45 N. ; so that when on the meridian, it is almost directly ove'r head in New England. It is on the same meridian with Orion, and culminates at the same hour of the night. Both of these constellations are on the meridian at 9 o'clock on the 24th of January, and 1 hour and 40 minutes east of it on the 1st of January. The whole number of visible stars in Auriga is sixty-six, including one of the 1st and one of the 2d magnitude, which mark the shoulders. Capella, a Aurigse, is the principal star in this constellation, and is one of the most brilliant in the heavens. It takes its name from Capella, the goat, which hangs upon the left shoulder. It is situated in the west shoulder of Auriga, 24 E. of Algol, and 28 N. E. of the Pleiades. It may be known by a little shai-p- pointed triangle formed by three stars, 3 or 4 this side of it, on the left. It is also 18 N. of p Tauri, which is common to the northern horn of Taurus, and the right foot of Auriga. Capella conies to the meridian on the 19th of January, just 2^ minutes 82 GEOGRAPHY OF THE HEAVENS, before j3, in the foot of Orion, which it very much resembles in brightness. Menkalina, $ Aurigse, in the east shoulder, is a star of the 2d magni- tude, 7 E. of Capella, and culminates the next minute after Betelguese, A Orionis, 3?3 S. of it. 6, in the right leg, is a star of the 4th magnitude, 8 directly south of Menkalina, It may be remarked as a curious coincidence, that the two stars in the shoulders of Auriga are of the same magnitude, and just as far apart as those in Orion, and opposite to them. Again, the two stars in the shoul- ders of Auriga, with the two in the shoulders of Orion, mark the ex- tremities of a long, narrow parallelogram, lying N. and S., and whose length is just five times its breadth. Also, the two stars in Auriga, and the two hi Orion, make two slender and similar triangles, both meeting in a common point, half way between them, at /g, in the northern horn of Taurus. Delta, a star of the 4th magnitude in the head of Auriga, is about 9 N. of the two in the shoulders, with which it makes a triangle, about half the hight of those just alluded to, with the vertex at Delta. The two stars in the shoulders are therefore the base of two similar triangles, one extending about 9 N., to the head, the other 18 S., to the heel, on the top of the horn : both figures together resembling an elongated diamond. Delta in the head, /3 in the right shoulder, and 6 in the arm of Auriga, make a straight line with Betelguese hi Orion, J* in the square of the Hare, and /3 hi Noah's Dove ; all being very nearly on the same meridian, 40 W. of the solstitial colure. " See next the Goatherd with his kids ; he shines With seventy stars, deducting only four, Of which Capella never sets to us, And scarce a star with equal radiance beams Upon the earth : two other stars are seen Due to the second order." Eudosia. TELESCOPIC OBJECTS. u AURIGJB. A. R. = 4 h. 48 m. 24 s. Dec. = -f 37 38' 5". A double star preceding the hip of Auriga. A 5. pale red ; B 9, light blue. Discovered by Sir W. Herschel, who records the following measures. Pos. = 352 37' Dist. = 5". 50 Epoch 1779.85 351 56 6 .46 18i8.75 Striive. Though the distances recorded by Herschel differ from the later ones, there is no reason to believe that the difference is due to an actual change in the places of these two stars. Herschel's means of making measures were less perfect than those now hi use ; and his measures are less to be relied on, from this cause. 5 AVRIOJE. A little north, and following a> Aurigse. A delicate double star. A 6, B 10 magnitude. Discovered by Striive, with the Polkova refractor. CONSTELLATION OF AURIGA. 83 A CLOSE DOUBLE STAR. A. R. = 4 h. 57 m. 11 s. Dec. = -\- 37 08' 4". On the lower garment of Auriga. A 7, B 8 magnitude, near a loose cluster. Discovered, by Strive, whose measures stood as follows : Pos. 219 12' Dist. = 1'<.61 Epoch 1828.60 14 AuniGas. A. R. = 5 h. 04 m. 59 s. Dec. = -j- 32 29' 8". A triple star in the right knee of Auriga. A 5, B 7|, C 16 magnitude. A and B have been long known, C was recently added by Prof. Striive. He records these measures. AB Pos. 225048' Dist. 14". 653 Epoch 1830.55 AC 342 37 12 .577 1830.55 A CLUSTER. A. R. = 5 h. 17 m. 18 s. Dec. = -{- 35 10' 3". On the robe under the left thigh of Auriga. This object is about 3' in diameter, and is composed of stars of various magnitudes, from the 10th to the 14th. It is preceded by a small double star. A 9^, B 1 1 magni- tude. Dist. 5".00 Discovered by Herschel. 1787. A RICH CLUSTER A. R. = 5 h. 18 m. 41 s. Dec. = -f- 35 44' 9". Dn the left thigh of Auriga. Discovered by Messier, 1764, and described by him as " a mass of stars of a square form, without any nebulosity, extending to about 15' of one degree." A RESOLVABLE NKBULA. A. R = 5 h. 20 m. 51 s. Dec. = -f- 34 06' 9". On the lower garment of Auriga. Discovered by Herschel in 1793, who says that it seems to have one or two stars in the middle, or an irregular nucleus. A FINE CLUSTER. A. R. = 5 h. 41 m. 46 s. Dec. =-{- 32 30' 1". In front of Auriga's left shin. Discovered by Messier, 1764, and described as "a mass of small stars in nebulous matter." 6 AURIGA. A. R. = 5 h. 48m. 48 s. Dec. -f- 37O 11' 7". A fine double star in the left wrist. A 4, lilac ; B 1 0, pale yellow. ' Pos. 28900' Dist. 30".00 Epoch 1832.64 41 AuniojE. A. R. = 5 h. 59 m. 21 s. Dec. = -f- 48 44' 1". On the chin of Auriga. A 7, white ; B 7, violet. Pos. 3530 07' Dist. 7".99 Epoch 1830.31 Struve. Many other double and triple stars, nebulse and clusters, may be found on the charts, and by alignment their places in the heavens may be readily made out. CONSTELLATION OF GEMINI. 85 CHAPTER II. DIRECTIONS FOR TRACING THE CONSTELLATIONS ON MAP NO. VII. GEMINI THE TWINS. CANCER THE CRAB. CANIS MINOR THE LITTLE DOG. Favorably situated for examination in January, Febru- ary ', March and April. GEMINI. THE TWINS. This constellation represents the twin brothers, Castor and Pollux. Gemini is the third sign, but fourth constellation in the order of the Zodiac, and is situated south of the Lynx, between Cancer on the east and Taurus on the west. The orbit of the earth passes through the center of the constellation. As the earth moves round in her orbit from the first point of Aries to the same point again, the sun, in the meantime, will appear to move through the opposite signs, or those which are situated right over against the earth, on the other side of her orbit. Accordingly, if we could see the stars as the sun appeared to move by them, we should see it passing over the constellation Gemini between the 21st of June and the 23d of July ; but we seldom see more than a small part of any constellation through which the sun is then passing, because the feeble luster of the stars is obscured by the superior effulgence of the sun. When the sun is just entering the outlines of a constellation on the H 80 GEOGRAPHY OF THE HEAVENS. east, its wester limits may be seen in the morning twilight, just above the rising sun. So when the sun has arrived at the western limit of a constellation, the eastern part of it may be seen lingering in the evening twilight, just behind the setting sun. Under other circumstances, when the sun is said to be in, or to enter, a particular constellation, it is to be understood that the constellation is not then visible, but that those opposite to it, are. For example : whatever constellation sets with the sun on any day. it is plain that the one opposite to it must be then rising, and continue visible throughout the night. Also, whatever constellation rises and sets with the sun to-day, will, six months hence, rise at sun- setting, and set at sun-rising. For example : the sun is in the center of Gemini about the 6th of July, and must rise and set with it on that day ; consequently, six months from that time, or about the 4th of January, it will rise in the east, just when the sun is setting in the west, and will come to the meridian at midnight ; being then exactly opposite to the sun. Now as the stars gain upon the sun at the rate of two hours every month, it follows that the center of this constellation will, on the 1 7th of February, come to the meridian three hours earlier, or at 9 o'clock in the evening. It would be a pleasant exercise for students to propose questions to each other, somewhat like the following: 'What zodiacal constellation will rise and set with the sun to-day ] What one will rise at sun-setting 1 What constellation is three hours high at sun-set, and where will it be at 9 o'clock ? What constellation rises two hours before the sun 1 How many days or months hence, and what hour of the evening or morning, and in what part of the sky shall we see the constellation whose center is now where the sun isl &c., &c. In solving these and similar questions, it may be remembered that the sun is in the vernal equinox about the 21st of March, from whence it advances through one sign or constellation every succeeding month there- after ; and that each constellation is one month in advance of the sign of that name : wherefore, reckon Pisces in March, Aries in April, Taurus in May, and Gemini in June, &c. ; beginning with each constellation at the 21st, or 22d of the month. Gemini contains eighty-five stars, including two of the 2d, four of the 3d, and six of the 4th magni- tudes. It is readily recognised by means of the tw r o principal stars, Castor and Pollux, a and ]3, of the 2d magnitude, in the head of the Twins, about 4j apart. There being only 11 minutes difference in the transit of these two stars over the meridian, they may both be considered as culminating at 9 o'clock about the 24th of February. Castor, in the head of Castor, is a star of the 2d magnitude, 4^ N. W. CONSTELLATION OF GEMINI. 87 of Pollux, and is the northernmost and the brightest of the two. Pollux is a star of the 2d magnitude, in the head of Pollux, and is 4j S. E. of Castor. This is one of the stars from which the moon's distance is calculated in the Nautical Almanac. " Of the famed Ledean pair, One most illustrious star adorns their sign, And of the second order shine twin lights." The relative magnitude or brightness of these stars has undergone considerable changes at differ- ent periods ; whence it has been conjectured by various astronomers that Pollux must vary from the 1st to the 3d magnitude. But Herschel, who observed these stars for a period of twenty-five years, ascribes the variation to Castor, which he found to consist of two stars, very close together, the less revolving about the larger once in 342 years and two months. Bradly and Maskelyne found that the line joining the two stars which form Castor was, at all times of the year, parallel to the line joining Castor and Pollux ; and that both of the former move around a common center between them, in orbits nearly circular, as two balls attached to a rod would do, if suspended by a string affixed to the center of gravity between them. " These men," says Dr. Bowditch, " were endowed with a sharpness of vision, and a power of penetrating into space, almost unexampled in the history of astronomy." About 20 S. W. of Castor and Pollux, and in a line nearly parallel with them, is a row of stars 3 or 4 apart, chiefly of the 3d and 4th magnitudes, which distinguish the feet of the twins. The brightest of these is Alhena, y, in Pollux's upper foot ; the next small star S. of it, is in his other foot : the two upper stars in the line next above y, mark Castor's feet This row of feet is nearly two-thirds of the distance from Pollux to Betelguese in Orion, and a line connecting them will pass through Alhena, the principal star in the feet. About two-thirds of the distance from the two in the head to those in the feet, and nearly parallel with them, there is another row of three stars about 6 apart, which mark the knees. There are, in this constellation, two other remarkable parallel rows, lying at right angles with the former ; one, leading from the head to the foot of Castor, the brightest star being in the middle, and in the knee ; the 88 GEOGRAPHY OF THE HEAVENS. other, leading from the head to the foot of Pollux, the brightest star, called Wasat, 2 CAXCRI. A. R. = 8 h. 17 m. 6 s. Dec. = -f- 2?o 27' 2". A close double star above the northern legs of Cancer. A 6, B 6^, magnitude. Its position is probably fixed. Pos. 2120 01' Dist. 4". 563 Epoch 1829.45 Struve. v I CANCRI. A. R. = 8 h. 1 7 m 08 s. Dec. = -}- 25O 03' 3". A double star on the crab's northern middle leg. A 7. B 7^. Discovered by Herschel, 1782. Measured by him as follows: Pos. 575l' Epoch 17S3.07 Herschel. In 1822, Sir James South and Sir John Herschel found the position to be 37 C 47', whence a rapid retrograde motion was inferred, but all subse- quent measures disprove this inference, and indicate a direct motion. Pos. 390 04' Dist. 5".7-23 Epoch 1841.35 Midler. 10' 05". A double star between the head of Hydra and Cancer. A 6, " pale yellow ; " B 7, " rose tint." Discovered by Herschel. Pos. 25045' Dist. 10". 33 Epoch 1832.95 Striive. 17 HYDROS. A. R. = 8 h. 47 m. 39 s. Dec. = 7 21' 08". A close double star between the Unicorn's tail and Hydra's heart. A and B 7 magnitude. Discovered by Herschel. Pos. 358 50' Dist. 4".33- Epoch 1831.59 Struve. 27 HERSCHEI IV, HYDROS. A. R. = 10 h. 17 m. 01 s. Dec. = 17 50' 06". A planetary nebula hi the middle of Hydra's body. Discovered by Herschel, 1785. OL CRATERIS. A. R. = 10 h. 52 m. 00 s. Dec. = 17 26' 09". A star with two distant companions on the base of the Cup. These are remarkable for then- color. A 4, orange ; B 8, blood red ; C 9, pale blue. Difference between A and B 42". 1 " A and C 4 .9 CONSTELLATION OF HYDRA. Ill 39 P. XI, CRATERIS. A. R = 11 h. 11 m. 38 s. Dec. = 06 01' 04". A small double star between the Cup and the Lion's hind feet A 8, B 9, magnitude. Discovered by Struve. Pos. 3140 00' Dist. 7".65 Epoch 1830.23 Struve. y CHATEHIS. A. R. = 11 h. 16 m. 54 s. Dec. = 16 48' 03". A close double star in the center of the goblet. A 4, B 14, magnitude. Discovered by Herschel. Pos. 10205' Dist 3".00 Epoch 1838.26 Smyth. 1 7 CRATERIS. A. R. = 1 1 h. 24 m. 2 1 s. Dec. = 28 23' 00". A double star in the boundary of the Cup. A 5 , B 7, magnitude. Discovered by Herschel, 1783. Pos. 207008' Dist 10".01 Epoch 1833.21 Smyth. CONSTELLATION OF VIRGO. 113 CHAPTER III. DIRECTIONS FOR TRACING THE CONSTELLATIONS ON MAP NO. XI. VIRGO THE VIRGIN. CORVUS THE CROW. Favorably situated for examination in April, May and June. VIRGO. THE VIRGIN. This is the sixth sign, and seventh constellation in the ecliptic. It is situated next east of Leo, and about midway between Coma Berenices on the N. and Corvus on the S. It oc- cupies a considerable space in the heavens, and contains, according to Flamsted, one hundred and ten stars, including one of the 1st., six of the 3d, and ten of the 4th magnitudes. Its mean declination is 5 N., and its mean right ascension is 195. Its center is therefore on the meridian about the 23d of May. The sun enters the sign Virgo, on the 23d of August, but does not enter the constellation before the 15th of September. When the sun is in this sign, the earth is in Pisces ; and vice versa. Spica Virginis, marked , in the ear of corn which the Virgin holds in her left hand, is the most brilliant star in this constellation, and situated nearly 15 E. N. E. of Algorab, marked , in the Crow, about 35 S. E. of Denebola, and nearly as far S. S. W. of Arcturus three very brilliant stars of the 1st mag- nitude, that form a large equilateral triangle, point- 114 GEOGRAPHY OF THE HEAVENS. ing to the S. Arcturus and Denebola, marked 0, are also the base of a similar triangle on the north, terminating in Cor Caroli, which, joined to the former, constitutes the Diamond of Virgo. The length of this figure, from Cor Caroli on the north, to Spica Virginis on the south, is 50. Its breadth, or shorter diameter, extending from Arcturus on the east, to Denebola on the west, is 35^. Spica may otherwise be known by its solitary splendor, there being no visible star near it, except one of the 5th magnitude, situated about 1 below it. on the left. The position of this star in the heavens, has been determined with great exactness for the benefit of navigators. It is one of the stars from which the moon's distance is taken for determining the longi- tude at sea. Its situation is highly favorable for this purpose, as it lies within the moon's path, and little more than 2 below the earth's orbit. Its right ascension being 199, it will come to our meridian at 9 o'clock about the 28th of May, in that point of the heavens where the sun is at noon about the 20th of October. Vindemiatrix, marked , is a star of the 3d magnitude, in the right arm, or northern wing of Virgo, and is situated nearly in a straight line with, and midway between Coma Berenices, and Spica Virginis. It is 19^ 6. W. of Arcturus, and about the same distance S. E. of Coma Berenices, and forms with these two a large triangle, pointing to the south. It bears also 18 S. S. E. of Denebola, and comes to the meridian about twenty- three minutes before Spica Virginis. Zeta, is a star 1 of the 3d magnitude, 11 N. of Spica, and very near the equinoctial. Gamma, situated near the left side, is also a star of the 3d magnitude, and very near the equinoctial. It is 13 due west of . with which and Spica it forms a handsome triangle. Eta, is a star of the 3d magnitude, in the southern wing, 5 W. of y, and but 2 E. of the autumnal equinox. Beta, called also Zavijava, is a star of the 3d magnitude, in the shoul- der of the wing, 7% W. of , with which and y, it forms a line near the earth's orbit, and parallel to it. & , y and Spica, form the lower and longer side of a large spherical triangle, whose vertex is in yg. The other stars in this figure may be easily traced by means of the map. About 1 3 E. of Spica, there are two stars of the 4th magnitude, 3 apart, which mark the foot of Virgo. These two stars are on nearly the same meridian with CONSTELLATION OF VIRGO. 115 Arcturus, and culminate nearly at the same time. The lower one marked Lambda, is on the south, and but 8 W. of the principal star in Libra. Several other stars of the 3d magnitude lie scattered about in this con- stellation, and may be traced out by the map. " Her lovely tresses glow with starry light ; Stars ornament the bracelet on her hand ; Her vest in ample fold, glitters with stars : Beneath her snowy feet they shine ; her eyes Lighten, all glorious, with the heavenly rays, But first the star which crowns the golden sheaf." ^ HISTORY. The famous zodiac of Dendera, as we have already noticed, commences with the sign Leo ; but another zodiac, discovered among the ruins at Estne, in Egypt, commences with Virgo ; and from this circum- stance, some have argued, that the regular precession of the equinoxes established a date to this at least 2000 years older than that at Dendera. The discoveries of Champollion, however, render it probable that this ancient relic of astrology at Estne was erected during the reign of the Emperor Claudius, and consequently did not precede the one at Dendera <>pore than fourteefi years. Of this, however, we may be certain : the autumnal equinox now cor- responds with the first degree of Virgo ; and, consequently, if we find a zodiac in which the summer solstice was placed where the autumnal equinox now is, that zodiac carries us back 90 on the ecliptic ; this divided by the annual precession of 50", must fix the date at about 6450 years ago. This computation, according to the chronology of the Sacred writings, carries us back to the earliest ages of the human species on earth, and proves, at least, that astronomy was among the first studies of mankind. The most rational way of accounting for this zodiac, says Jamieson, is to ascribe it to the family of Noah ; or perhaps to the patri- arch himself, who constructed it for the benefit of those who should live after the deluge, and who preserved it as a monument to perpetuate tLe actual state of the heavens immediately subsequent to the. creation. TELESCOPIC OBJECTS. A NKBUOA. A. R. = 12h. 06 m. 01 s. Dec. = -f 15 47' 02". This nebula is situated between Virgo's right wing and Leo's tail. Discovered by Messier, 1781, and described by him as " a nebula with- out a star, with an extremely faint light. A Loxe PALE-WHITE NEBULA. A. R. = 12 h. 07 m. 37 s. Dec. 4- HO 02' 08". On the upper part of Virgo's left wing. Described in the Bedford Catalogue as " a very curious object, resembling a weaver's shuttle, and lying across the parallel. The upper branch is the faintest, and exhibits a palpable nucleus." Discovered by Herschel, 1783. A LARGE NEBULA. A. R. = 12 h. 13 m. 45 s. Dec. = -f 05 116 GEOGRAPHY OF THE HEAVENS. 21' 06". This nebula is situated between the Virgin's shoulders. Her- schel reports it to have two neuclei about 90" apart. Discovered by Messier, 1799. 1? VIRGINS. A. R. = 12 h. 14 m. 24 s. Dec. 06O 1 1' 08". A double star between the shoulders of Virgo. A 6, B 9, magnitude. Pos. 336045' Dist 19".32 Epoch 1829.26 Struve. The components appear to be stationary. A ROUND NEBULA. A. R. = 12 h. 14 m. 52 s Dec. = -}- 16 42' 06". It appears off the upper part of the Virgin's left wing. Discovered by Mechain, 1781. It is one of a multitude of nebulous masses forming a wonderful zone, and passing round the heavens in a direction nearly perpendicular to the Milky Way. The discovery of this great stratum, is the result of the unwearied zeal and perseverance of Sir William Herschel. A BRIGHT NEBULA. A. R. = 12 h. 21 m. 36 s. Dec. -f- 08 52' 09". This nebula is situated on Virgo's left shoulder. Discovered by Orioni, 1771. A LONG ELLIPTICAL NEBULA A. R. = 12 h. 23 m 54 s. Dec. = -f- 15 18' 05". It appears on the outer side of Virgo's left wing. In a zone three degrees square a large number of nebulae are found, whose relative positions are exhibited in the diagram marked nebulae in Virgo. y VIRGINIS. A. R. = 12 h. 33 m. 33 s. Dec. = 00 34' 03". A remarkable binary star, on the Virgin's right side. A 4, B 4, magni- tude. In consequence of some very early observations, by Bradly, Pound, Cassini, and Mayer, it was thought that this star presented an admirable opportunity of testing the influence of gravitation among these remote objects. As early as 1718, the positions of the components seem to have been approximately obtained. Measures were again made in 1720, 1756, and by Sir W. Herschel in 1780. These, combined with modem observations, furnished the data for the computation of the elements of the orbits, described by these two suns about their common center of gravity. From the earliest period of observation, the distance between the two stars composing y Virginia, had been on the decrease, while the angular velocity was rapidly increasing ; following, in this respect, the analogy of the planets and comets, whose angular velocity rapidly increases as their distance from the sun decreases. Sir John Herschel made the first effort at a determination of the elements of the orbit, and found a period of 513.28 years by the first computed elements, and of 628.90 years by the second set of elements. These results were greatly in error, owing to the fact, as Sir John Herschel says, to the use of Bradly's observations of 1718. In the meantime M. Mildler, of Dorpat, had shown that the periodic time could not well exceed 1 57 years, a result finally reached by Herschel himself. After much laborious calculation, M. Miidler reached the conclusion that the perihelion or pereaster passage occurred 1836.31, and that the Pos. H59 53' 0(i" Dist. 02".417 357 43 04 02 .556 355 55 06 02 .689 354 1H 03 02 .816 352 39 06 02 .9:59 351 13 06 0:5 .057 349 53 05 03 .170 CONSTELLATION OF VIRGO. 117 periodic time was 145.409 years. With his last set of elements, he has computed an ephemeris of this system, from which we copy as follows: Epoch 1847 1848 1849 1850 1851 1852 1853 During a part of the year 1836, the star was seen perfectly round, even in the most powerful instruments. Objects which had been so widely separated, when first discovered, were now so placed as that the one eclipsed the other. Towards the close of 1836, the hidden star began to emerge, and this double object was seen elongated. At the beginning of I 37, the best telescopes again saw the two stars separate and distinct. From that time, to the present, the distance has been on the increase, while the angular velocity has been regularly diminishing. My own observations show the ephemeris computed by Mildler, to be pretty ac- curate, but even yet considerable discordance exists between observation and computation, showing that more accurate data are yet wanted to complete this most delicate and difficult investigation A few measures are here given. Pos. = 319007' Dist. 07".49 Epoch 172031 CassinL 350 04 --- 1781.89 Herschel I. 285 04 02 .80 182200 Strive. 262 10 01 .58 183059 Bessel. 245 32 01 .05 1833.:<7 Strive. 077 55 00 .58 1837.41 Struve. 020 11 01 .7-< 1841.44 Midler. Oil 06 01 .90 1843.33 Smyth. 357 28 03 .09 1847.60 MitcheL By a comparison of the last observations with the ephemeris, it will be seen that the angular velocity is greater than predicted, as is also the in- crease of distance between the components. 6 VIIUJTNIS. A. R. = 13 h. 01 m. 40 s. Dec. = 04 41' 00". A coarse triple star on the lower part of the Virgin's southern wing. A 4^, B 9, (J. 10, magnitude. Pos. A B 344002' Dist. 07". 02 Epoch 1 837.07 ? Q , A C 295 00 65 .00 1831.155 y ' A CLOSE BIXATIY STAR. A. R. = 13 h. 26 m. 07 s. Dec. = -{- 00 30' 04". This star is situated on Virgo's lower garment. A 8, B 9, magnitude. Discovered by Stri'ive, 1825. Poe. 100 00' Dist. 01".600 Epoch 1825.37 Struve. 24 08 01 .590 1834.38 Struve. 36 02 01 .747 1841.37 Midler. The period of revolution is, probably, not far from 230 years. 81 VIRGINIS. A. R. = 13 h. 29 m. 13 s. Dec. = 07 03' 02". 118 GEOGRAPHY OF THE HEAVENS. A close double star on the right side of the lower garment of the Virgin. Suspected of slow retrogradation. Pos. 41 07' Dist. 02".82 Epoch 1841.39 Mudler. 84 VIRGINS A. R. = 13 h. 35 m 02 s. Dec. = -}- 04 21' 00". A close double star on the tip of Virgo's left wing. A i, B 9, magnitude. Pos. 23304' Dist. 03".5 . Epoch 1839.37 Smyth. 231 05 03 .48 1847.06 Mitchel. 9 VIRGINIS. A. R. = 14 h. 19 m. 58 s. Dec. = Ol c 30' 04". A delicate double star in the corner of Virgo's skirt. A 5, yellow ; B 13, blue. Discovered by Strive, 1829. Pos. 108 32' Dist. 03".73 Epoch 1829.71 Struve. Other double stars and nebulae will be found on the chart. A DOUBLE NEBULA. A. R. = 12 h. 35 m. 33 s. Dec. = -f- 12 26' 1". This nebula is situated in the center of Virgo's left wing, with two or three smaller ones in the immediate vincinity. In this object we find some support to the celebrated nebular theory, which supposes the sun and stars to have been formed from the condensation of nebulous fluids. The object before us suggests the chaotic state of a binary star, and possi- bly these two shadowy objects are performing, even now, a revolution round each other. Abandoning this theory, and having recourse to the idea that these dim stains are mighty universes of shining stars, here we have two such so located as possibly to be mutually operating upon each other. Should actual physical connection exist, and one of these mighty systems be actually sweeping round the other, what a stupendous period must mark the cycle of these " island universes." By such periods we might even reckon the hours of eternity itself ! " CORVUS. THE CROW. This small constellation is situated on the eastern part of Hydra, 15 E. of the Cup, and is on the same meridian with Coma Berenices, but as far S. of the equinoctial as Coma Berenices is N. of it. It therefore culminates at the same time, on the 12th of May. It contains nine visible stars, including three of the 3d magnitude, and two of the 4th. This constellation is readily distinguished by means of three stars of the 3d magnitude, and one of the 4th, forming a trapezium or irregular square, CONSTELLATION OF CORVUS. 119 the two upper ones being about 3-z apart, and the two lower ones 6 apart. The brightest of the two upper stars, on the left, is called Algorab, marked a, and is situated in the E. wing of the Crow ; it has nearly the same declina- tion S. that the Dog-star has, and is on the meridian about the 13th of May. It is 21^ E. of Alkes in the Cup, 14^ S. W. of Spica Virginis, a brilliant star of the 1st magnitude, to be described in the next chapter. Beta, on the back of Hydra and in the foot of the Crow is a star of the 3d magnitude, nearly 7 S. of Algorab. It is the brightest of the two lower stars, and on the left. The right hand lower one is a star of the 4th magnitude, situated in the neck, marked Epsilon, about 6 W. of j3, and may be known by a star of the same magnitude situated 2 below it, in the eye, and called Al Chiba. t is 21 J S. of the vernal equinox, and if a meridian should be drawn from the pole through Megrez, and produced to Corvi, it would mark the equinoctial colure. Gamma in the W. wing, is a star of the 3d mag- nitude, 3^ W. of Algorab, and is the upper right hand one in the square. It is but 1 E. of the equi- noctial colure. 10 E. of j3 is a star of the 3d magnitude, in the tail of Hydra, marked y ; these two. with Algorab, form nearly a right angled triangle, the right angle being at |3. TELESCOPIC OBJECTS, &. A double star, on the Bear's left hind foot, A 4, B 12. Pos. 147 02' Dist. 7".8 Epoch 1834.31 URsas MAJORTS MIJAR. A. R. = 13 h. 17 m. 28 s. Dec. = -|- 550 4.V 08". A beautiful double star, in the middle of the tail of the Bear, A 3, B 5, magnitude. Pos. 1450 20' Dist. 14".24 Epoch 1819.70 Struve. 147 24 14 .40 1839.32 Smyth. It is uncertain whether any physical connection exists between the two components, though an identity of proper motion would lead us to think them united. In exhibiting this double star to those not familiar with the heavens, on taking the eye from the telescope, and looking at the star with the unaided vision, many persons exclaim that they see the small star with the naked eye. This is, however, a mistake. The faint star really seen is not the one shown by the telescope, but a much more distant minute star, called Alcor. Indeed, with the great refractor of the Cincinnati Observatory, Alcor, which to the eye appears so very close to Mizar, does not even fall within that field of view of the telescope, which is occupied by Mizar in its center. From the fact that Alcor and Mizar have an identity of proper motion, it has been argued that they may constitute a binary system two suns revolving around their common center of gravity. Should this be true, L2 126 GEOGRAPHY OF THE HEAVENS. and their distance be assumed as great as that assigned to stars of the same magnitude, they cannot complete their revolution in a period less than 190,000 of our years! In the Memoirs of the Observatory of the Collegio Romano, 1842, some singular notices of Mizar are made, which I venture to translate. I give the substance of the notices as follows : On the 18th April, 1841, M. Mlidler communicated to M. Arago the singular fact that, at 9 o]clock and 8 minutes, on that evening, he had seen Mizar without a companion. About 10 o'clock, the small star re- appeared in all its brilliancy. He thinks he had observed the same phenomenon, with an" inferior instrument, in 1 834, and infers that the small star is variable, with a long period. The Italian astronomers report the detection of four minute points in the same field with Mizar, some or all of which appear to be variable. DIRECTIONS FOR TRACING THE CONSTELLATIONS ON MAP NO. XIII. BOOTES THE BEAR DRIVER. CORONA BOREALIS THE NORTHERN CROWN. . QUADRANS THE QUADRANT. CANES VENATICI THE GREY HOUNDS. COMA BERENICES BERENICES' HAIR. Favorably situated for examination in May, June and July. P O T E S . THE BEAR DRIVER is represented by the figure of a huntsman in a running posture, grasping a club in his right hand, and holding up in his left the leash of his two grey hounds, Asterion and Chara, with which he seems to be pursuing the Great Bear round the pole of the heavens. He is thence called Arcto- phylax, or the " Bear Driver." This constellation is situated between Corona Borealis, on the east, and Cor Caroli, or the Grey- hounds, on the west. It contains fifty-four stars - CONSTELLATION OF BOOTES. 127 including one of the 1st magnitude, seven of the 3d, and ten of the 4th. Its mean declination is 20 N., and mean right ascension is 212 ; its center is therefore on the meridian the 9th of June. Bootes may be easily distinguished by the position and splendor of its principal star, Arcturus, which shines with a reddish luster, very much resembling that of the planet Mars. Arcturus, marked a, is a star of the 1st magnitude, situated near the left knee, 26 S. E. of Cor Caroli and Coma Berenices, with which it forms an elon- gated triangle, whose vertex is at Arcturus. Five or six degrees S. W. of Arcturus are three stars of the 3d and 4th magnitudes, lying in a curved line, about 2 apart, and a little below the left knee of Bootes; and about 7 E. of Arcturus are three or four other stars of similar magnitude, situated in the other leg, making a larger curve N. and S. Mirac, marked e, in the girdle, is a star of the 3d magnitude, 10 N. N. E. of Arcturus, and about 11 W. of Alphacca, or <* in the Northern Crown. Seginus, marked -y, in the west shoulder, is a star of the 3d magnitude, nearly 20 E. of Cor Caroli, and about the same distance N. of Arcturus, and forms, with these two, a right angled triangle, the right angle being at Seginus. Alkaturops, marked p, situated in the top of the club, is a star of the 4th magnitude, about 10 3 in an easterly direction from y, which lies in the left shoulder : and about 4 S. of Alkaturops is another star of the 4th magnitude, in the club near the east shoulder, marked Delta tT is about 9 distant from Mirac, and 73 from Alphacca, and forms, with these two, a regular triangle. Nekkar, marked /2, is a star of the 3d magnitude, situated in the head, and is about 6 N. E. of Seginus, and 5 W. of Alkaturops ; it forms with tT and Seginus, nearly a right angled triangle, the right angle being at Nekkar, These are the principal stars in this constellation, except the three stars of the 4th magnitude situated in the right hand. These stars may be known, by two of them being close together, and about 5 beyond Benetnasch, the first star in the handle of the Dipper. About 6 B. of Benetnasch is another star of the 4th magnitude, situated in the arm, which forms, with Benetnasch and the three in the hand, an equilateral triangle. Arcturus is mentioned by name in that beautiful passage in Job, already referred to, where the 128 GEOGRAPHY OF THE HEAVENS. Almighty answers " out of the whirlwind," and says : " Canst them the sky's benevolence restrain, A nd cause the Pleiades to shine in vain 1 Or, when Orion sparkles from his sphere, Thaw the cold seasons and unbind the year ? Bid Mazzaroth his station know, And teach the bright Ardurus where to glow ! " Young's Paraphrase. TELESCOPIC OBJECTS. i Bor.Tis. A. R. = 14 h. 10 m. 30 s. Dec. = -f- 52 06' 04". A delicate triple star in the right hand of Bootes. A 4, B 4, C 8, magnitude. Discovered by Struve. A B Pos. 149 00' Dist. 00". 3 Epoch 1836.28 ? ~ ., AC 33 09 38 .06 1836.28 5 Ot A WHITE ROUND NEBULA. 14 h. 11 m. 44 s. Dec. = 37 14' 04" Discovered by Herschel, on 1st May, 1785. A NKAT DOUBLE STAR. A. R. = 14 h. 15 m. 31 s. Dec. = -f- 09 10' 07". Between the left foot of Bootes and Virgo, on a line be- tween Spica, Bootis. A 6, B white, B 7, blue. Discovered by Piazzi. Pos. 186003' Dist. 06".26 Epoch 1825.40 Struve. TT BOOTIS. A. R. = 14 h. 33 m. 12 s. Dec. = -f- l?o 06' 05". On the left leg. A 3, B 6, magnitude. ' Pos. 99003' Dist. 08".00 Epoch 1836.51 Smyth. 96 57 08 .28 1847.60 Mitchel. f BOOTIS. A. R. = 14 h. 33 m. 31 s. Dec. = -f- 140 25' 01". A close double star on the left leg of Bootes. A 3, B 4. Discovered by Herschel, 1796. Pos. 1290 IT Dist. 05". 190 Epoch 1830.47 Struve. 128 24 06 .924 1847.62 Mitchel. This result, after an interval of seventeen years, determines, it would seem, the fixity of the components, though from early observations mo- tion had been suspected. BOOTIS. A. R. = 14 h. 38 m. 00 s. Dec. == -f- 27 45' 01". A fine double star on the left hip of Bo tes. A 3, pale orange; B 7, sea green. This is certainly one of the most beautLoil among the double stars. Discovered by Herschel. Pos. 320 47' Dist. 02". 581 Epoch 1831.41 Struve. 323 38 02 .917 1841.41 Mlldler. 320 50 02 .568 1846.66 Mitchel. CONSTELLATION OF BOOTES. 129 BoC-ris. A. R. = 14 h. 44 m. 00 s. Dec. = -f- 19 46' 01". A binary star on the left knee of Bootes. A 3, orange ; B 6^, purple. The orbit was computed by Sir John Herschel in 18:33, but with little success. Mildler thinks the periodic time cannot be nearly so short as that obtained by Herschel. It will probably exceed 400 years. Discovered by Herschel, 1780. Pos. 334 10' Dist. 07".22 Epoch 1829.46 Stn.ve. 324 41 07 .09 1841.43 M:;dler. 317 44 06 .482 1817.63 Mitchel. A SMALL NEBULA. A. R. = 14 h. 53 m. 53 s. Dec. = -j- 54 32' 07". Between the right hand of Bootes and Draco. Discovered by Herschel, 1788. 39 BOOTIS. A. R. = 14 h. 44 m. 16 s. Dec. = -f- 49 22' 08". On the right wrist of Bootes. A 5, B 6, magnitude. Pos. 440 12' Dist 03". 71 Epoch 1830.02 Struve. 37 00 04 .00 1847.60 Mitchel. These measures show a retrograde motion, as do all the previous ones.* 44 Boons. A. R. = 14 h. 58 m. 31 s. Dec. = -f- 48 16' 08". A close double star in the space following the right arm of Bo"tes. A 5, B 6, magnitude. This star has occasioned no little difficulty, owing to the abrupt changes which have occurred in the relative positions of the components. Mildler thinks Herschel's first observation is wrong by 180 degrees ; an error easily committed, considering the near equality of the two stars. On this hypothesis the periodic time may not differ much from sixty or seventy years. A few measures are added. Pos. 60006' Dist. 02".00 Epoch 1781.62 Herschel. 228 00 01 .50 1819.43 Struive. 233 39 02 .55 1829.30 Struve. 237 02 04 .068 1841.47 Midler. 238 20 03 .738 1847.62 Mitchel. p 2 BOUTIS. A. R. = 15 h. 18 m. 28 s. Dec. = -j- -37 54' 07". A binary star on the tip of the staff of Bootes. A 8, B 8, magnitude. The components are preforming their revolution in a retrograde order, and in a period of 300 or 400 years. 1'hese measures will show the rate of motion. Pos. 3570 14' Dist. Epoch 1782.68 Herschel. 327 00 01 ".385 1826.77 Struve. 315 04 01 .060 1830.65 Struve. 308 43 06 .885 1841.46 Madler. 130 GEOGRAPHY OF THE HEAVENS. DRACO.* THE DRAGON. This constellation, which com- passes a large circuit in the polar regions by its ample folds and contortions, contains many stars which may be easily traced. From the head of the monster, which is under the foot of Hercules, there is a complete coil tending eastwardly, about 17 N. of Lyra ; thence he winds down northerly about 14 to the second coil, where he reaches almost to the girdle of Cepheus, then he loops down somewhat in the shape of the letter U, and makes a third coil about 15 below the first. From the third coil he holds a westerly course for about 13, then goes directly down, passing be- tween the head of the Lesser and the tail of the Greater Bear. This constellation contains eighty stars, including four of the 2d magnitude, seven of the 3d, and twelve of the 4th. *... " The Dratrwi next, winds like a mighty stream ; Within its ample folds are eighty stars, Four of the second order. Far he waves His ample spires, involving either Bear." The head of the Dragon is readily distinguished by means of four stars, 3, 4, and 5 apart, so situ- ated as to form an irregular square ; the two upper ones being the brightest, and both of the 2d magni- tude. The right hand upper one, called Etanin, has been rendered very noted in modern astronomy from its connection with the discovery of a new law in ' physical science, called the Aberration of Light. The letter name of this star is Gamma, or Gamma Draconis ; and by this appellation it is most fre- quently called. The other bright star, about 4 from it on the left, is Rastaben, marked . * See Map XVII for part of Draco. CONSTELLATION OF DRACO. 131 About 4 W. of ]3, a small star may, with close attention, be discerned in the nose of the Dragon, which, with the irregular square before mentioned, makes a figure somewhat resembling an Italic F, with the point towards the west, and the open part towards the east. The small star in the nose, is called Er Rakis, marked p. The two small stars 5 or 6 S. of Rastaben are in the left foot of Hercules. Rastaben is on the meridian nearly at the same moment with Ras Alhague. Etanin, 40 N. of it, is on the meridian about the 4th of August, at the same time with the three western stars in the face of Taurus Poniatowski, or the V. It is situated less than 2 west of the solstitial colure, and is exactly in the zenith of London. Its favorable position has led English astronomers to watch its appearance, for long periods, with the most exact and unwearied scrutiny. In the year 1725, Mr. Molyneux and Dr. Bradley fitted up a very accurate and costly instrument, in order to discover whether the fixed stars had any sensible parallax, while the earth moved from one extremity of its orbit to the other ; or which is the same, to determine whether the nearest fixed stars are situated at such an immense distance from the earth, that any star which is seen this night directly north of us, will, six months hence, when we shall have gone 1 90 millions of miles to the eastward of the place we are now in, be then seen exactly north of us still, without changing its position so much as the thickness of a spider's web. These observations were subsequently repeated, with but little inter- mission, for twenty years, by the most acute observers in Europe, and with telescopes varying from twelve to thirty-six feet in length. In the meantime, Dr. Bradley had the honor of announcing to the world the very nice discovery, that the motion of light, combined with the progressive motion of the earth in its orbit, causes the heavenly bodies to be seen in a different position from what they would be, if the eye were at rest. Thus was established the principle of the Aberration of Light. This principle, or law, now that it is ascertained, seems not only very plain, but self evident. For if light be progressive, the position of the telescope, in order to receive the ray, must be different from what it would have been, if light had been instantaneous, or if the earth stood still. 132 GEOGRAPHY OF THE HEAVENS. Hence the place to which the telescope is directed, will be different from Jie true place of the object. The quantity of this aberration is determined by a simple proj>osition. The earth describes 59' 8" of her orbit in a day = 3548", and a ray of light comes from the sun to us in 8' 13" = 493" : now twenty -four hours or 86400" : 493" : : 3548" : 22" ; which is the change in the star's place, arising from the cause above mentioned. Of the four stars forming the irregular square in the head, the lower and right hand one is 5^ N. of Etanin. It is called Grumium, and is of the 4th magnitude. A few degrees E. of the square, may be seen, with a little care, eight stars of the 5th magnitude, and one of the 4th, which lies 8 E. of Grumium. This group is in the first coil of the Dragon. The second coil is about 13 below the first, and may be recognised by means of four stars of the 3d and 4th magnitudes, so situated as to form a small square, about half the size of that in the head. The brightest of them is on the left, and is marked Delta. A line drawn from Rastaben through Grumium, and produced about 14, will point it out. A line drawn from Lyra through Zi Draconis, and pro- duced 10 farther, will point out Zeta, a star of the :*d magnitude, situated in the third coil. " may otherwise be known, by its being nearly in a line with, and midway between. Etanin and Koohab. From the re- maining stars in. this constellation are easily traced. Eta, 7'heta, and Arich, come next ; all stars of the 3d magnitude, and at the distance, severally, of 6, 40 anc | 50 f rO m At Asich, the third star from the tail of the Dragon makes a sudden crook. Thubun, Kappa, Giansar, follow next, and complete the tail. Thuban, marked a, is a bright star of the 3d mag- nitude, 11 from Asich, in a line with, and about midway between, Mizar and the southernmost guard in the Little Bear. By nautical men this star is called the Dragon's Tail, and is considered of much importance at sea. It is otherwise celebrated as being formerly the north polar star. About 2,300 years before the Christian era, Thuban was ten times nearer the true pole of the heavens than Cynosura now is. Kappa is a star of the 3d magnitude, 10 from Alpha, between Megrez and the pole. Mizar and Megrez, in the tail of the Great Bear, form, with Thuban and x., in the tail of the Dragon, a large quadrilateral figure, whose longest side is from Megrez to *. Giansar, the last star in the tail, is between the 3d and 4th magni- tudes, and 5 from K. The two pointers will also point out Giansar, lying at the distance of little more than 8 from them, and in the direction of the pole. CONSTELLATION OF DRACO. 133 TELESCOPIC OBJECTS. AN OVAL NEBULA. A. R. = 15 h. 02 m. 03 s. Dec. = -\- 56 23'. Under the body of Draco. Discovered by Herschel, 1789. It is faint at the edges. A SMALL ROUND NEBULA. A. R. = 15 h. 35 m. 53 s. Dec. -|- 59 52'. In the center of Draco's body. Discovered by Herschel, 1788. This object brightens at the center, presenting a nucleus not very per- fectly denned. It is followed in the same field by a much larger elon- gated nebula, which seems to have escaped all preceding observers. It was discovered, 4th July, 1847, by Mrs. Mitchel, while engaged in a critical examination of the abova object. It is faint, but certain, and haa an oval or elliptical figure. p. DRACONIS A. R. = 17 h. 02 m. 02 s, Dec. = 54 41' 02". A fine binary star, on the tip of Draco's tongue. A 4, B 4^, magnitude. Discovered by Herschel, 1781. Since which period a retrograde mo- tion has been in progress, as is fully sustained by the reported measures, viz. Pos. 2320 22' Dist. 4".35 Epoch 1781.73 Herschel. 205 06 3 .23 1832.22 Stn.ve. 190 57 2 .90 1847.70 Mitchel. 4 1 DHACOXIS. A. R. = 17 h. 44 m. 47 s. Dec. -f- 71 I.T. A double star, in the middle of Draco's back. A 5, B 6. Both white. This distance is about 3 1 "; the position 15. No change seems to have taken place. See Map, No XVII. A DOUBLE STAR. A. R. = 17 h. 25 m. 07 s. Dec. = -\- 50 59' 09". Between the right foot of Hercules and Draco's eye. A 8, B 8, magnitude. Pos. 265 28' Dist. 3". 17 Epoch 1831.29 Strive. 266 20 3 .03 1847.70 Mitchel. A PLANETARY NEBULA. A. R. ^= 17 h. 58 m. 39 s. Dec. 66O 38'. Between the first twist of Draco and his head. Discovered by Herschel, in 1786. This singular object is described in the Bedford Catalogue, without any mention of a remarkably bright but .small nucleus which occupies its center. This point was detected by myself, July, 1847. When the eye and attention is attentively fixed on the central point, the nebula fades from the view, and the moment the attention is withdrawn from the nucleus, and a casual glance is directed to the nebula, the star fades and the nebula brightens up in a most beautiful manner. This curious phenomenon was noticed by many persons in my company. No one can doubt the connection between this nebulous mass and the round central point of light. It is unlike a star, as it is round and clear, with a minute disk and no radiations. I have discovered but one other object like it. Here is the connecting link between planetary nebulse and JVL 134 GEOGRAPHY OF THE HEAVENS. nebulous stars ; at least, such would be the opinion of those who still adhere to the nebulous theory. This remarkable object, as will be seen from the position, is in the pole of the ecliptic. o DHACONIS. A. R. = 18 h. 48 m. 50 s. Dec. = -}- 59 11' 07". A double star, on Draco's neck. A 5, B 9, magnitude. Midler thinks the components physically connected, with a period of about 1600 years. Pos. OOOQO' Dist 26". 37 Epoch 1781.68 Herschel. 346 33 30 .26 1832.50 Strilve. 344 51 32 .10 1841.48 Mildler. t DRACOJTIS. A. R = 19 h. 48 m. 41 s. Dec. 69 51' 06". In the bend of Draco's back. A 5, B 9^, magnitude. Discovered by Herschel, whose first measures are probably wrong in some way, as they would indicate a great motion, between 1781 and 1804, which is not sustained by the later observations. Pos. 355040' Dist. 2".6 9:3 Epoch 184]. 55 Mlldler. COMA BERENICES. BERENICE'S HAIR. This is a beautiful cluster of small stars, situated about 5 E. of the equinoctial colure, and midway between CorCaroli on the north- east, and Denebola on the southwest. If a straight line be drawn from Benetnasch through Cor Caroli, and produced to Denebola, it will pass through it. The principal stars are of between the 4th and 5th magnitudes. According to Flamsted, there are thir- teen of the 4th magnitude, and, according to others, there are seven ; but the student will find, agreeably to his map, that there are but three stars in this group entitled to that rank. Although it is not easy to mistake thjs group for any other in the same region of the skies, yet the stars which compose it are all so small as to be rarely distinguished in the full presence of the moon. The confused luster of this assemblage of small stars, somewhat resembles that of the Milky- Way. It contains, besides the stars already alluded to, a number of nebulae. CONSTELLATION OF COMA BERENICES. 135 The whole number of stars in this constellation is 43; its mean right ascension is 185. It, conse- quently, is on the meridian the 13th of May. Now behold The glittering maze of Berenices Hair ; Forty the stars ; but such as seem to kiss The flowing tresses with a lambent fire : Four to the telescope alone are seen." TELESCOPIC OBJECTS. 35 COMJE BERNICES. A. R. = 12 h. 45 m. 25s. Dec. =4. 22 07'. A triple star, between the Tresses and Virgo's 1 northern wing. A 5, B indistinct, C 10. Such are the magnitudes assigned by Captain Smyth. I measured the components on the *27th July, 1847, and found the individual measures accord well with each other. Pos. A B = 400 04' Dist. = I".3l6 Epoch as above. AtoC 125 31 In 1 830, Strilve gives the measures of A to C as follows : Pos. AtoC 124043' Dist. 28".61 Epoch 1830.13. Captain Smyth makes the distance between A and B, in 1834, T'.OO. In 1843, 1".5. 64 MESSIER, Coyim BERNICES. A. R. = 12 h. 48 m. 52 s. Dec. -f- 22 33' 02". A large elliptical nebula, between Bernice's hair and Virgo's left arm. Discovered by Messier, 1780. Sir John Herschel considers this nebula resolvable, though not re- solved. He says : " I am much mistaken if the nucleus be not a double star, in the general direction of the nucleus ; 320 much increases this sus- picion ; 340 shows well a vacuity below the nucleus." 53 MESSIER, COM*: BERNICES. A. R. = 13 h. 05 m. 03 s. Dec. = -|- 19 01' 03". A globular cluster, between the Coma and Virgo's left hand. A brilliant mass of minute stars, varying from the llth to the 16th magnitudes. Discovered by Messier, 1774. Resolved by Herschel, who finds it greatly compressed at the center. This is one of the many magnificent " island universes." Sir John Herschel, with his 20 feet reflector, saw this object with curved radiations of stars, somewhat resembling the claws of a crab. 42 COM;E BERNICES. A. R. == 13 h. 02 m. 12 s. Dec. = -f- 18 22' 06". A very close double star, between the Lady's hair and Virgo's left hand. A 4^, B 5, magnitude. Both stars are said to be pale-yel- low. It is No. 1728 of StriJve's great catalogue, and is among his " vicinissimae," or very closest stars. The measures run thus : 136 GEOGRAPHY OF THE HEAVENS. Pos. 0930' Dist. Epoch 1827.83 Strive. 11 06 0".649 1829.40 single 1833.37 228 18 somewhat elongated 1834.43 191 12 1335.39 After this, the measures are made with Jittle variation, up to 18-11. when Madler, of Dorpat, gives these : Pos. 183 15' Dist 0".327 Epoch 1841.45. Here is, doubtless, a binary system, but one of great difficulty. The stars being nearly equal in magnitude, it is difficult to distinguish the angle of position from the same, increased by 180. ASTERION ET CHARA; VEL CANES VENATICI. THE GREYHOUNDS. This modern constellation, embracing two in one, was made by Hevelius out of the unformed stars of the ancients, which were scattered between Bootes on the east, and Ursa Major on the west, and between the handle of the Dipper on the north, and Coma Berenices on the south. These Hounds are represented on the celestial sphere as being in pursuit of the Great Bear, which Bootes is hunting round the pole of heaven, while he holds in his hand the leash by which they are fastened together. The northern one is called As- tcrion, and the southern one Chara. The stars in this group are considerably scatter- ed, and are principally of the 5th and 6th magni- tudes ; of the twenty-five stars which it contains, there is but one sufficiently large to engage our at- tention. Cor Caroli, marked a, or Charles's Heart, so named by Sir Charles Scarborough, in memory of King Charles the First, is a star of the 3d mag- nitude, in the neck of Chara, the southern Hound. When on the meridian, Cor Caroli is 17^ directly south of Alioth, the third star in the handle of the Dipper, and is so nearly on' the same meridian, that it culminates only one minute and a half after it. This occurs on the 20th of May. A line drawn from Cor Caroli, through Alioth, will lead to the north polar star. This star may also be readily distinguished by its being in a CONSTELLATION OF THE HOUNDS. 137 straight line with, and midway between, JBenetnasch, the first star in the handle of the Dipper, and Coma Berenices : and, also, by the fact that, when Cor Caroli is on the meridian, Denehola bears 28 S. W., and Arcturus 26 S. E. of it, forming, with these two stars, a very large tri- angle, whose vertex is at the north. It is also at the northern extremity of the large Diamond, already described. The remaining stars in this constellation are too small, and too much scattered, to excite our interest. . ' ? TELESCOPIC OBJECTS. 2 CAWVM VEJTATICORUM. A. R. = 12 h. 08 m. 06 s. Dec. = -f- 410 33'. A double star, near Chara's mouth. A 6, yellow ; B 9, blue. Discovered by Herschel, 1782. Pos. 2590 38' Dist 11 ".42 Epoch 1832.16 Struve. . Its fixity seems to be determined by a comparison of all the recorded observations. A LARGE NEBULA. A. R. = 12 h. 43 m. 2 ' s. Dec. 41 5*9' 07". Immediately preceding the Crown, or Charles's Heart. Discovered by Michain, in 1781. Described in the Bedford Catalogue as " a fine pale white object, with evident symptoms of being a com- pressed cluster of small stars." 51 M. CAHTUM VENATICORUM. A. R. = 13 h. 23m. 06s. Dec. = -f- 48 01' 07". A pair of lucid nebula, near the ear of Asterion. Discovered by Messier, 1772. Figured by Sir John Herschel, 1830. Resolved by Lord Rosse, into one magnificent cluster, in the shape of an immense whirlpool, in 1847. I have repeatedly examined this most wonderful object with the 12 inch refractor of the Cincinnati Observatory. The large nebula is seen with a bright nucleus, surrounded by a ring of hazy light, which is di- vided, in a part of its circumference, into two branches, which ' forcibly remind me of the Milky- Way and its division. The smaller nebula is round, and its light is seen, nearly, if not quite, commingling with that of the ring surrounding the principal object. This object strongly resembled our own great stellar system, so long as it was viewed at the distance to which ordinary telescopes could carry the beholder. But, under the gaze of Lord Rosse's stupendous reflector, the most bewildering object bursts upon the sight. A mighty center, where, in spiral curves, radiate masses of light, so vast as to overwhelm the imagination. The resolution of this most remarkable nebula is one of the great achievements of Lord Rosse's telescope. 3 MESSIER, CAJTUM VEXATTCORUM. A. R. = 13 h. 34 m. 45 s. Dec. = -j- 29 10' 06". A magnificent cluster, said to contain not less than a thousand stars, between the southern Hound and the knee of Bootes. Discovered by Messier, 1764 ; and described as " a nebula without a star, brilliant and round." Resolved by Herschel, 1784, with his 20 M2 138 GEOGRAPHY OF THE HEAVENS. feet reflector, who calls it " a beautiful cluster of stars, 5' or 6' in diame- ter." I have repeatedly examined this fine object. The mass of stars is greatly compacted together at the center, and spread out in brilliant radiations in all directions. The largest radiations extend downward, as seen with an inverting eye-piece. CORONA BOREALIS. THE NORTHERN CROWN. This beautiful constella- tion may be easily known by means of its six prin- cipal stars, which are so placed as to form a circular figure, very much resembling a wreath or crown. It is situated directly north of the Serpent's head, between Bootes, on the west, and Hercules, on the east. This asterism was known to the Hebrews by the name of Ashtaroth ; and by this name the stars in Corona Borealis are called, in the East, to this day. Alphacca, marked o, of the 2d magnitude, is the brightest and middle star in the diadem, and about 11 E. of Mirac, in Bootes. It is very readily dis- tinguished from the others, both on account of its position and superior brilliancy. Alphacca, Arctu- rus and Seginus, form nearly an isosceles triangle, the vertex of which is at Arcturus. This constellation contains twenty-one stars, of which only six or eight are conspicuous; and most of these are not larger than the third magnitude. Its mean declination is 30 north, and its mean right ascension 235. Its center is, therefore, on the meridian about the last of June, and the first of July. " And, near to Helice, effulgent rays Beam, Ariadne, from thy starry crown : Twenty and one her stars ; but eight alone Conspicuous ; one doubtful, or to claim The second order, or accept the third." CONSTELLATION OF LEO MINOR. 139 .f ^ DIRECTIONS FOR TRACING THE CONSTELLATIONS ON MAP NO. XIV. LEO MINOR THE LITTLE LION. LYNX THE LYNX. Favorably situated for examination in March, April and May. LEO MINOR. THE LITTLE LION. This constellation was formed by Hevelius, out of the Stella i?iformes, or unformed stars of the ancients, which lay scattered between the zodiacal constellation Leo, on the south, and Ursa Major, on the north. Its mean right ascension is the same with that of Regulus, and it comes to the meridian at the same time, on the 6th of April. The modern constellations, qr those which have been added to our celestial maps, since the adoption of the Greek notation, in 1603, are referred to by the letters of the English alphabet, instead of the Greek. This is the case in regard to Leo Minor, and all other constellations whose origin is subsequent to that period. Leo Minor contains fifty-three stars, including only two of the 4th magnitude. The principal star is situated in the body of the animal, 13 north of Gamma Leonis, in a straight line with Phad, and may be known by a group of smaller stars, a little above it, on the northwest. It forms an equilateral triangle with Gamma and Delta Leonis, the vertex being in Leo Minor. This star is marked with the letter /, in modern catalogues, and, being the principal representative of the constel- lation, is itself sometimes called the Little Lion : 8 E. of this star (the Little Lion), are two stars of the 4th magnitude, in the last paw of Ursa Major ; and about 10 N. W. of it, are two other stars, of the 3d mag- nitude, in the first hind paw. " The Smaller Lion now succeeds; a cohort Of fifty stars attends his steps ; And three, to sight unarmed, invisible." 140 GEOGRAPHY OF THE HEAVENS. TELESCOPIC OBJECTS. 200 HERSCHEL I, LEGISTS MIDORIS. A. R. = 8 h. 42 m. 44 s. Dec. = -f- 340 00' 06". A bright oval nebula, between Lynx and Cancer. Discovered by Herschel, 1787 ; and registered as a very beautiful ne- bula, 8' long and 3' broad. Other nebula will be found on the chart. THE LYNX. THE constellation of the Lynx, like that of the Camelopard, exhibits no very interesting features, by which it can be distinguished. It contains only a moderate number of inferior stars, scattered over a large space, north of Gemini and between Auriga and Ursa Major. The whole number is forty-four, including only three that are so large as the 4th magnitude. The largest of these, in the nose, is in the solstitial colure, 14 north of Menkalina, in the east shoulder of Auriga. The other two principal stars are in the brush of the tail, 3J south- west of another star, of the same brightness, in the mouth of the Lesser Lion, with which it makes a small triangle. Its center is on the meridian at 9 o'clock, on the 23d, or, at half-past 7, on the 1st, of February TELESCOPIC OBJECTS. 4 LYWCIS. A. R. = 6 h. 07 m. 51 a. Dec. = -|- 59 25' 08". A close double star, in the nose of the Lynx. A 6, B 7. Discovered by Struve. Pos. 88056' Dist 0".815 Epoch 1830.28 Struve. 174 P. VI, LTNCIS. A. R. = 6 h. 30 m. 42 s. Dec. -f- 59 35' 06". A double star, under the eye of the Lynx. A 7, white, B 10, blue. Discovered by Struve. Pos. 133028' Dist. 4". 197 Epoch 1830.58. The companion appears to be variable, ranging from 8 to the 12th magnitude. 14 LYNCIS. A. R. 6 h. 38 m. 57 s. Dec. = 59 37' 06" A close CONSTELLATION OF THE LYNX. 141 double star, under the eye of the Lynx. A 5, "golden yellow," B 1, " purple." Discovered bv Struve. Pos. 50051'" Dist. 0"897 Epoch 1830.88 137. HKRSCHKL I, LYNCIS. A. R. = 09 h. 14 m. 32s. Dec. -f- 35 1 1' 09". A bright nebula, on the fore paws of Leo Minor, but in- cluded within the limits of the Lynx. Discovered by Herschel, in ! 786, who describes it as round, pale white, and sparkling in the center, with an additional faint nebulosity surround- ing the nucleus. Some 3' in diameter. DIRECTIONS FOR TRACING THE CONSTELLATION ON MAP NO. XV. LIBRA THE SCALES. Favorably situated for examination in May, June and July. LIBRA. THE BALANCE. -This is the seventh sign, and eighth constellation, from the vernal equinox, and is situ- ated in the Zodiac, next east of Virgo. The sun enters this sign, at the autumnal equi- nox, on the 23d of September; but does not reach the constellation before the 27th of October. Virgo was the goddess of justice, and Libra, the scales, which she is usually represented as holding in her left hand, are the appropriate emblems of her office. When the sun enters the sign Libra, the days and nights are equal all over the world, and seem to observe a kind of equilibrium, like a balance. When, however, it is said that the vernal and autumnal equinoxes are in Aries and Libra, and the tropics in Cancer and Capricorn, it must be remem- bered that the signs, Aries and Libra, Cancer and 142 GEOGRAPHY OF THE HEAVENS. Capricorn, and not the constellations of these na nes, are meant; for the. equinoxes are now in the con- stellations Pisces and Virgo, and the tropics in Ge- mini and Sagittarius ; each constellation having gone forward one sign in the ecliptic. About twenty-two centuries ago, the constellation Libra coincided with the sign Libra; but, having advanced 30, or more, in the ecliptic, it is now in the sign Scorpio, and the constellation Scorpio is in the sign Sagittarius, and so on. While Aries is now advanced a whole sign above the equinoctial point, into north declination, Libra has descended as far below it. into south declination. Libra contains fifty-one stars, including two of the 2d magnitude, and several of the 4th. Its mean declination is 8 south, and its mean right ascension 226. Its center is, therefore, on the meridian about the 22d of June. It may be known by means of its four principal stars, forming a quadrilateral figure, lying north- east and southwest, and having its upper and lower corners nearly in a line running north and south. The two stars which form the northeast side of the square are situated about 7 apart, and distinguish the northern scale. The two stars which form the southwest side of the square are situated about 6 apart, and distinguish the southern scale. Zubeneschamali, marked $, in the northern scale, about 21 E. of Spica, and 8 E. of Lambda Virginis, is a star of the 2d magnitude, and is situated very near the ecliptic, about 42^ E. of the autumnal equinox. The distance from this star down to Theta Ceutauri, is about ti3, with which, and Spica Virginis, it forms a large triangle, on the right. Zubenelgemabi, marked a., is also of the 2d magnitude, 9^o below Zubeneschamali, towards the southwest, and it comes to the meridian about twenty-six minutes after it, on the 23d of June. Zubenelgemabi is the northernmost of the four bright stars in this figure, and is exactly opposite the lower one, which is 1 1 S. of it. The star marked y, is a star of the 3d magnitude, in the north- ern scale, 7 S. E. of Zubenelgemabi, and nearly opposite to Zubenes- chamali, at the distance of 11 on the east. These two make the diagonal of the square east and west. CONSTELLATION OF LIBRA. 143 Ma is a star of the 4th magnitude, and constitutes the southernmost c< ner of the square. It is about 6 S. E. of Zubeneschamali, and 1 1 8 of Zubenelgemabi, with which it forms the other diagonal, north and so ith. Zubenelgubi is a star of the 2d magnitude, situated below the southern scale, at the distance of 6 from Iota, and marks the southern limit of the Zodiac. It is situated in a right line with, and nearly midway between, Spica Virginis and Beta Scorpii ; and comes to the meridian nearly at the same moment with Nekkar, in the head of Boutes. The remaining stars in the constellation are too small to engage attention. The scholar, in tracing out this constellation hi the heavens, will per- ceive that Lambda and Mu, which lie in the feet of Virgo, on the west, form, with Zubeneschamali and Zubenelgemabi, almost as handsome and perfect a figure as the other two stars in the Balance do, on the east. TELESCOPIC OBJECTS. A DOUBLE STAR. A. R. = 14 h. 14 m. 1 1 s. Dec. = 07 01' 07". 15, east by north, from Spica Virginis. The stars are equal, and of the 8th magnitude Pos. 160008' Dist. 5".02 Epoch 1836.44 Smyth. A CLOSE DOUBLE STAU . A. R. = 14 h. 16 m. 06 s. Dec. 10 56' 03". Close to the heel of the Virgin. A 7, yellow, B 9, greenish. Discovered by Strive, ,1827. Pos. 3260 87' Dist. 1".41 Epoch 1829.83. A CLOSELY COMPACTED CLUSTER. A. R. = 15 h. 10m. 26s, Dec. = -f- 020 41' 03". Over the Balance. Discovered by Messier, 1764, who registers it as a round nebula, in which, he is confident, not a star exists; and yet, in May, 1791, Sir William Herschel, by the aid of his 40 feet reflector, counted in this ob- ject no less than 200 stars This is one of the great clusters comparatively near our sidereal stra- tum, and somewhat resembling that in Hercules, hereafter described and figured. The drawing was made under a power of 280, and 12 inches aperture, the object was thus described. g OR 51 LiBna:. A. R. = 15 h. 58 m. 35 s. Dec. = 10 55 06 . A most elegant triple star, between the upper scale of Libra and the right leg of Ophiuchus. A 4, B 5, magnitude. Pos. A B 187 56' Dist. 1" .50 Epoch 1782.36? , , AC 88 37 6 .38 1 780.39 5 HerscheL AB355 58 1 .147 1825.487 -, .. A C 78 36 6 .75 - 5 otruve - A B 16 43 1 .28 1841.48 AC 74 40 6 .75 - A B 24 52 .97 1846.48 .. , , AC 74 42 7 .16 - - 5 MltcneL The disks are perfect, with a power of 600 times, 144 GEOGRAPHY OF THE HEAVENS. A LARGE COMPRESSED- CLUSTER. A. R. = 15 h. 08 m. 06 s. Dec. = 20 26' 07". Discovered by Herschel, 1785. It forms a sort of connecting link be- tween the congeries of stars and the distant nebulae. DIRECTIONS FOR TRACING THE CONSTELLATION ON MAP NO. XVI. SCORPIO THE SCORPION. Favorably situated for examination in June, July, and August. SCORPIO. THE SCORPION. This is the eighth sign, and ninth constellation, in the order of the Zodiac. It pre- sents one of the most interesting groups of stars, for the pupil to trace .out, that is to be found in the southern hemisphere. It is situated southward and eastward of Libra, and is on the meridian the 10th of July. The sun enters this sign on the 23d of October, but does not reach the constellation before the 20th of November. W hen astronomy was first cultivated in the East, the two solstices and the two equinoxes took place when the sun was in Aquarius and Leo, Taurus and Scorpio, respectively. Scorpio contains, according to Flamsted, forty- four stars; including one of the 1st magnitude, one of the 2d, and eleven of the 3d. It is readily dis- tinguished from all others, by the peculiar luster and the position of its principal stars. Antares, marked a, is the principal star, and is situated in the heart of the Scorpion, about 19 E. of Zubenelgubi,the southernmost star in the Balance. Antares is the most brilliant star in that region of CONSTELLATION OF SCORPIO. 145 the skies, and may be otherwise distinguished by its remarkably red appearance. Its declination is about 26 S. It comes to the meridian about three hours after Spica Virginis, or fifty minutes after Corona Borealis, on the 10th of July. It is one of the stars from which the moon's distance is reck- oned, for computing the longitude at sea. There are four great stars in the heavens, Fomalhaut, Aldebaran, Regulus, and Antares, which formerly answered to the solstitial and equinoctial points, and which were much noticed by the astronomer* of the East About 8 N. W. of Antares, is a star of the 2d magnitude, in the head of the Scorpion, called Grqffias, marked ^3. It is but 1 N. of the earth's orbit. It may be recognized by means of a small star, situated about 1 N. E. of it, and also by its forming a slight curve with two other stars of the 3d magnitude, situated below it, each about 3 apart. The broad part of the constellation near Graffias is powdered with numerous small stars, converging down to a point at Antares, and resem- bling in figure a boy's kite. As you proceed from Antares, there are ten con- spicuous stars, chiefly of the 3d magnitude, which mark the tail of the kite, extending down, first in a south-southeasterly direction, about 17, thence easterly, about 8 further, when they turn, and ad- vance about 8 towards the north, forming a curve, like a shepherd's crook, or the bottom part of the letter S. This crooked line of stars, forming the tail of the Scorpion, is very conspicuous, and may be easily traced. The first star below Antares, which is the last in the back, is of only the 4th magnitude. It is about 2 S. E. of Antares, and is marked T. Epsilon, of the 3d magnitude, is the second star from Antares, and the first in the tail. It is situated about 7 below the star T, but inclining a little to the east Mu, of the 3d magnitude, is the 3d star from Antares. It is situated N 146 GEOGRAPHY OF THEl HEAVENS. 4 below Epsilon. It may otherwise be known by means of a small star close by it, on the left. Zetay. of about the same magnitude, and situated about as far below Mu, is the fourth star from Antares. Here the line turns suddenly to the east. Eta, also of the 3d magnitude, is the fifth star from Antares, and about 3 east of Zeta. Theta, of the same magnitude, is the sixth star from Antares, and about 4$ E. of Eta. Here the line turns again, curving to the north, and terminates in a couple of stars. lota, is the seventh star from Antares, 3 above Theta, curving a lit- tle to the left. It is a star of the 3d magnitude, and may be known by means of a small star almost touching it. on the east. Kappa, a star of equal brightness, is less than 2 above Iota, and a little to the right. Lesuth, of the 3d magnitude, is the brightest of the two last in the tail, and is situated about 3 above Kappa, still further to the right. It may readily be known by means of a smaller star close by it, on the west This is a very beautiful group of stars, and easily traced out in the heavens. It furnishes striking evidence of the facility with which most of the con- stellations may be so accurately delineated as to preclude every thing like uncertainty in the knowl- edge of their relative situation. " The heart, with luster of amazing force, Refulgent vibrates; faint the other parts, And ill-defined by stars of meaner note." TELESCOPIC OBJECTS. ANTARES, OR a. SCORPII. A. R. = 16 h. 19 m. 36 s. Dec. = 260 04' 03". Discovered to be double, at the Cincinnati Observatory, July, 1845. A 1, orange, B 12, blue. The contrast of color is distinctly marked. The small star follows the principal one. on the same parallel. Distance 2". 5. The principal star was pronounced to be double, by the Wash- ington observers, in August, 1846, but this error has been subsequently corrected. This forms the most remarkable double star now on the cata- logues, there being no star of the 1st magnitude known, having so minute a companion, at so short a distance. It was first divided with a power of 250, and aperture of 12 niches. The best power for measures is 500, with an aperture reduced to 9 inches. My measures indicate a slight increase in the distance between the two components. This, however, requires confirmation. v SCORPII.=A. R. = 16 h. 02 m. 42 s. Dec. = 19 02' 03". Registered as a double star. Discovered to be triple, at the Cincinnati CONSTELLATION OF SCORPIO. 147 t Observatory, 1846. A and B nearly equal, and of the 6th magnitude; C 7, magnitude. Distance from A to B = I ".2 From A -f- B to C 40".00 ~~2~~ Pos. A -f- B to C = 3380 29' 2 -'V From A to B = 37 57 This star was first seen double by Herschel, in 1779 ; but its great southern declination brought it too near the horizon, in the latitude of his observatory, to see the close star?: The same may be said of Antares. I have recently received intelligence, that measures of Antares have been made in England, 1847. a- SCORPH. A. R. = 16 h. llm. 28 s. Dec. = 25 12' 02". A delicate double star, 2 W. by N. from Antares. A 4, B 9^, mag. Pos. 271 05' Dist. 20". 04 Discovered by Herschel, 1783. There is no evidence of any change in the relative position ot the components. Pos. 2710 05' Dist. 22". 34 Epoch 1817.60 'Mitchel. SCORPII A. R. = 15 h. 56 m. 18 s. Dec. = 19 21' 07". A second rate Greenwich star. Discovered to be double by Herschel, 1779. A 2, B 5^, magnitude. -Miidler thinks this a binary system of long period. The measures are as follow : Pos. 25009' Dist. I4".37 Epoch 1779 72 Herschel. 26 30 13 .65 1823.28 Her. & South. My own measures are : Pos. 260 22' Dist. 13".68 Epoch 1846 50. Agreeing nearly with Herschel and South. The Bedford Catalogue gives : Pos. 24009' Dist. 13".0l Epoch 1835.39. From these measures, there is very little evidence of any change, either in distance or angle of position. A LARGE AND BRILLIANT CLUSTER. A. R. = 16 h. 07 m. 28 s. Dec. 220 35' 04". Discovered by Messier, in 17SO, who describes it as resembling the nucleus of a comet. It is 4 E. of / Scorpii. and midway between A and /g. It is remarkable as being located on the western edge of an im- mense opening, or vacant spot, in the heavens, of 4 in breadth, in which the most powerful telescopes reveal no st irs ! The center of this cluster is very brilliant, ana the surrounding points of light profusely scattered Herschel regards it as one of the richest and most condensed masses of stars yet discovered in the heavens. Examined and figured, 2d August, 1847. A SMALL COMPRESSED CLUSTER. A. R. = 16 h. 13 m. 51 s. Dec. = 26 07' 05". It precedes Antares l^o on the same parallel. Discovered by Messier. Resolved by Herschel; who estimates its profundity of the 344th order. 148 GEOGRAPHY OF THE HEAVENS. This condensed group is also on the western edge of the opening above referred to, and has given rise to the following remarks by Arago. referring to the idea expressed by Herschel, that, wherever chasms in the heavens are found, near by, extensive clusters and nebula will be discovered. " Let us," says M A rago, " connect these facts with the observation which has shown that the stars are greatly condensed toward the center of the spherical clusters, and with that which has afforded the proof that these stars sensibly obey a certain power of condensation (or clustering power), and we shall feel disposed to admit, with Herschel, that nebulfe are formed sometimes, by the incessant operation of a great number of ages, at the expense of the scattered stars which originally occupied the surrounding regions ; and the existence of empty or ravaged spaces to use the picturesque expression of the great astronomer, will no longer present any thing which will confound the imagination " A LARGE RESOLVABLE NEBULA. A. R. = 16 h. 51 m. 04 s. Dec. 290 50' 06". Discovered by Messier. Resolved by Herschel ; who estimates its dis- tance to be of the 73 Ith order. It resembles a comet, and has been reported as such, at least once, in a very public manner. All the reported clusters hi this constellation are readily detected by any ordinary telescope. Their resolution does not require a high power. But to show them in all their richness and brilliancy, a powerful instru- ment is necessary. DIRECTIONS FOR TRACING THE CONSTELLATIONS ON MAP NO. XVII. URSA MINOR THE LESSER BEAR. CEPHEUS. CAMELOPARDUS THE CAMELOPARD. Favorably situated for examination in March, April, and May. URSA MINOR. THE LITTLE BEAR. This constellation, though not remarkable in its appearance, and containing but few conspicuous stars, is, nevertheless, justly dis- tinguished from all others, for the peculiar advan- tages which its position in the heavens is well known to afford to nautical astronomy, and espe- cially to navigation and surveying. CONSTELLATION OF URSA MINOR. 14il The stars in this group being situated near the celestial pole, appear to revolve about it, very slowly, and in circles so small as never to descend below the horizon. In all ages oi the world, this constellation has been more universally observed, and more carefully noticed than any other, on account of the import- ance which mankind early attached to the position of its principal star. This star, which is so near the true pole of the heavens, has from time immemorial, been denomi- nated the NORTH POLAR STA^. By the Greeks it is called Cynosure : by the Romans, Cynosum, and by othes nations, Alruccabah. It is of the 3d magnitude, or between the 2d and 3d, and situated a little more than a degree and a half from the true pole of the heavens, on that side of it which is towards Cassiopeia, and opposite to Ursa Major. Its position is pointed out by the direction of the two Pointers, Merak and Dubhe, which lie in the square of Ursa Major. A line join- ing Cassiopeia, which lies at the distance of 32 on one side, and Megrez, which lies at the same dis- tance on the other side, will pass through the polar star. So general is the popular notion, that the North Polar Star is the true pole of the world, that even surveyors and navigators, who have acquired con- siderable dexterity in the use of the compass and the quadrant, are not aware that it ever had any devia- tion, and consequently never make allowance for any. All calculations derived from the observed position of this star, which are founded upon the idea that its bearing is always due north of any place, are necessarily erroneous, since it is in this position only twice in twenty-four hours; once when above, and once when below the pole. According to the Nautical Almanac, the mean dis- N2 150 GEOGRAPHY OF THE HEAVENS. tance of this star from the true pole of the heavens, for the 1st Jan. 1849, is 1 29' 28", and its mean right ascension is 1 h. 5 m. and 10.60s. Consequently, when the right ascension of the meridian of any place is 1 h. 5 m. and 10.66 s. the star will be exactly on the meridian at that time and place, but 1 29' 28" above the true pole. Six hours after, when the right ascension of the meridian is 7 h. 5 m. and 10.66 s. the star will be at its greatest elongation, or 1 29' 28" directly west of the true pole, and par- allel to it, with respect to the horizon ; and when the right ascension othe meridian is 13 h. 5 m. and 10.66s. the star will be again on the meridian, but at the distance of 1 29' 28" directly below the pole. In like manner, when the right ascension of the meridian is 19 h. 5m. and 10.66s. the star will be at its greatest eastern elongation, or 1 29' 28" east of the true pole ; and when it has finished its revolution, and the right ascension of the meridian is 25 h. 5 m. and 10.66 s. or, what is the same thing, 1 h. 5 m. and 10.66 s. the star will now be on the meridian again, 1 29' 28" above the pole. N. 13. The right ascension of the meridian or of the midheaven, is the distance of the lirst point of Aries from the meridian, at the time and place of observation. The right ascension of the meridian for any time, is found, by adding to the given time the sun's right ascension at the same time, and deducting 24 hours, when the sum exceeds 24 hours. From the foregoing facts we learn, that from the time the star is on the meridian, above the pole, it deviates farther and farther from the true meridian, every hour, as it moves to the west, for the space of six hours, when it arrives at its greatest elongation west, whence it reapproaches the same meridian below the pole, during the next six hours, and is^ then again on the meridian; being thus alternately half the time west of the meridian, and half the time east. of it. CONSTELLATION OF URSA MINOR. 151 Hence, it is evident that the surveyor who regu- la es his compass by the North Polar Star, mast take his observation when the star is on the merid- ian, either above or below the pole, or make allow- ance for its altered position in every other situation. For the same reason must the navigator, who ap- plies his quadrant to this star for the purpose of determining the latitude he is in, make a similar allowance, according as its altitude is greater or less than the true pole of the heavens ; for we have seen that it is alternately half the time above and half the time below the pole. The method of finding the latitude of a place from the altitude of the polar star, as it is quite sim- ple, is very often resorted to. Indeed, in northern latitudes, the situation of this star is more favorable for this purpose than that of any other of the heav- enly bodies, because a single observation, taken at any hour of the night, with a good instrument, will give the true latitude, without any calculation or correction, except that of its polar aberration. If the polar star always occupied that point in the heavens which is directly opposite to the north pole of the earth, it would be easy to under- stand how latitude could be determined from it in the northern hemisphere ; for in this case, to a person on the equator, the poles of the world would be seen in the horizon. Consequently, the star would appear just visible in the northern horizon, without any elevation. Should the person now travel one degree towards the north, he would see one degree below the Star, and he would think it had risen one degree. And since we always see the whole of the upper hemisphere at one view, when there is nothing in the horizon to obstruct our vision, it fol- lows that if we should travel 10 north of the equator, we should see just 10 below the pole, which would then appear to have risen 10; and should we stop at the 42d degree of north latitude, we should, in like manner, have our horizon just 42 below the pole, or the pole would ap- pear to have an elevation of 42. Whence we derive this general truth: Tfte elevation of the pole of the equator, is always equal to the latitude of the place of observation. Any instrument, then, which will give us the altitude of the north pole, will give us also the latitude of the place. The method of illustrating this phenomenon, as given in most treatises on the globe, and as adopted by teachers generally, is to tell the scholar 152 GEOGRAPHY OF THE HEAVENS. that the north pole rises higher and higher, as he travels farther and farther towards it. In other words, whatever number of degrees he ad- vances towards the north pole, so many degrees will it rise above his horizon. This is not only an obvious error in principle, but it misleads the apprehension of the pupil. It is not that the pole is elevaled, but that our horizon is depressed as we advance towards the north. The same objection lies against the artificial globe ; for it ought to be so fixed that the horizon might be raised. or depressed, and the pole remain in its own invariable position. Ursa Minor contains twenty-four stars, including three of the 3d magnitude and four of the 4th. The seven principal stars are so situated as to form a figure very much resembling that in the Great Bear, only that the Dipper is reversed, and about one half as large as the one in that constellation. The first star in the handle, called Cynosura, or Alruccabah, is the polar star, around which the rest constantly revolve. The two last in the bowl of the Dipper, corresponding to the Pointers in the Great Bear, are of the 3d magnitude, and situated about 15 from the pole. The brightest of them is called Kochab, which signifies an axle or hinge, probably in reference to its moving so near the axis of the earth. Kochab may be easily known by its being the brightest and middle one of three conspicuous stars forming a row, one of which is about 2, and the other 3, from Kochab. The two brightest of these are situated in the breast and shoulder of the animal, about 3 apart, and are called the Guards or Pointers of Ursa Minor. They are on the meri- dian about the 20th of June, but may be seen at all hours of the night, when the sky is clear. Of the four stars which form the bowl of the Dipper, one is so small as hardly to be seen. They lie in a direction towards Gamma in Cepheus; but as they are continually changing their position in the heavens, they may be much better traced out from the map, than from description. CONSTELLATION OF URSA MINOR. 153 Kochab is about 25 distant from Benetnasch, and about 24 from Dubhe, and hence forms with them a very nearly equilateral triangle. " The Lesser Bear Leads from the pole the lucid band ; the stars Which form this constellation, faintly shine, Twice twelve in number ; only one beams forth Conspicuous in high splendor, named by Greece The Cynosure,- by us the POLAH STAR." The following stars have small telescopic com- panions : a or the pole star. or Kochab, the right hand upper star in the bowl of the little dipper. The left hand upper star in the bow). The companion discovered 1841, by Prof. Challis, with the Northumberland equatorial, at Cambridge, England. * The star near the root of the tail. Companion 12th magnitude, pale blue. 8 The star next but one to Polaris, in the tail. The principal star is of a greenish tinge, while the companion is grey. There are a few faint nebulae in this con- stellation. CEPHEUS. CEPHEUS is represented on the map as a king, in his royal robe, with a scepter in his left hand, and a crown of stars upon his head. He stands in a commanding posture, with his left foot over the pole, and his scepter extended towards Cassiopeia, as if for favor and defense of the queen. " Cepheus illumes The neighboring heavens ; still faithful to his queen, With thirty-five faint luminaries mark'd." This constellation is about 25 N. W. of Cas- siopeia, near the 2d coil of Draco, and is on the meridian at 8 o'clock the 3d of November; but it will linger near it for many days. Like Cassiopeia, it may be seen at all hours of the night, when the sky is clear, for to us it never sets. 154 GEOGRAPHY OF THE HEAVENS. By reference to the lines on the map, which all meet in the pole, it will be evident that a star, near the pole, moves over a much lts& spai e in one hour, than one at the equinoctial ; and generally, the nearer the pole, the narrower the space, and the slower the motion. The stars that are so near the pole, may be better described by their polar distance, than by their declination. By polar distance, is meant the distance from the pole ; and is what the declination wants of 90. In this constellation there are 35 stars visible to the naked eye; of these, there glitters on the shoulder, a star of the 3d magnitude, called Alder- afnin, marked a, which with two others of the same brightness, 8 and 12 degrees apart, form a slightly curved line towards the N. E. The last, whose letter name is Kappa, is in the right knee, 19 N. of Caph, in Cassiopeia. The middle one in the line, is Alphirk, marked j3, in the girdle. This star is one- third of the distance from Alderamin to the pole, and nearly in the same right line. It cannot be too well understood that the bearings, or directions of one star from another, as given in this treatise, are strictly applicable only when the former one is on, or near the meridian. The bearings given, in many cases, are the least approximations to what appears to be their relative position ; and in some, if relied upon, will lead to errors. For example :-i-It is said, in the preceding paragraph, that Kappa, in Cepheiis, bears 19 N. of Caph in Cassiopeia. This is true, when Caph is on the meridian, but at this very moment, while the author is writing this line, Kappa appears to be 19 due west of Caph ; and six months hence, will appear to be the same distance east of it. The reason is obvious ; the circle which CepheuS appears to describe about the pole, is within that of Cassiopeia, and consequently when on the east of the pole, will be within, or between Cassiopeia and the pole that is. west of Cassiopeia. And for the same reason, when Cephe^s is on the west side of the pole, it is between that and Cassiopeia, or east of it. Let it also be remembered, that in speaking of the pole, which we shall have frequent occasion to do, in the course of this work, the North Polar Star, or an imaginary point very near it, is always meant ; and not as some will vaguely apprehend, a point in the horizon, directly N. of us. The true pole of the heavens, is always elevated just as many degrees above our horizon, as we are north of the Equator. If we live in 42 N. latitude, the N. pole will be 42 above our horizon. (See North Polar Star.) There are also two smaller stars about 9 E. of CONSTELLATION OF CEPHEUS. 155 Alderamin and Alphirk, with which they form a square; Alderamin being the upper, and Alphirk the lower one on the W. 8 apart. In the center of this square there is a bright dot, or semi- visible star. The head of Cepheus, is in the Milky-Way, and may be known by three stars of the 4th magnitude in the crown, which form a small acute triangle, about 9 to the right of Alderamin. The mean polar distance of the constellation is 25, while that of Alderamin is 28 10'. The right ascension of the former is 338 ; consequently, it is 22 E. of the equinoctial colure. \ TELESCOPIC OBJECTS. x CKPHEI. A, R. = 20 h. 14 m. 08 s. Dec. = -f- 77 13' 06". A fine double star on the right knee, about half-way from /3 Cephei to t Ursse Minoris. A 4^, white, B 8, blue, The colors well defined. Pos. 1260 12' Dist ()7".08 Epoch 1820.18 Striive. 123 08 07 .50 1838.83 Smyth. There is little evidence of any change in the position of the components. /2 CKPHEI. A. R. = 21 h. 26 m. 31 s. Dec. = -f- 69 51' 07". A fine double star, on the left side of the girdle. A 3, B 8, magnitude. Pos. 251000' Dist. 13".07 Epoch 1843.16 Smyth. CAMELOPARDUS. THE CAMELOPARD. This constellation was made by Hevelius out of the unformed stars which lay scattered between Perseus, Auriga, the heajfl of Ursa Major, and the Pole Star. It is situated directly N. of Auriga and the head of the Lynx, and occu- pies nearly all the space between these and the pole. It contains nearly 58 small stars; the five largest of which are only' of the 4th magnitude. The principal star lies in the thigh, and is about 20 from Capella, in a northerly direction. It marks the northern boundary of the temperate zone; being less than one degree S. of the Arctic circle. There are two other stars of the 4th magnitude near the 156 GEOGRAPHY OF THE HEAVENS. right knee, 12 N. E. of the first mentioned. They may be known by their standing 1 apart and alone. The other stars in this constellation are too small, and too much scattered to invite observation. TELESCOPIC OBJECTS. A BRIGHT PLANETAE* NEBULA. A. R. = 03 h. 53 m. 29 s. Dec. 60 23' 05". On the flank of the Camelopard. See map, No. VI. Discovered by Herschel, 1787. 1 CAMELOPARBI. A. R. = 04 h. 19 m. 23'. Dec. = -\- 53 33' 03". A double star between the hind hoofs. A 7$, "white," B 8, * blue." See map, No. VI. Pos. 307 05' Dist. 10". 13 Epoch 1830.57 StrLve. 2 CAMELOPARDI. A. R. = 04 h. 27 m. 18 s. Dec. 53 09' 00". A close double star, near the preceding one, and between the hind hools. A 5$, yellow, B 7, pale blue. See map, No. VI. Discovered by Struve, and thus measured by him : Pos. 311040' Dist. 1".585 Epoch 1829.79. A DOUBLE STAB. A. R. = 04 h. 56 m. 19 s. Dec. = -\- 79 1 ' 08". Over the lower part of the back of the Camelopard. A 5, B 9, magnitude. Pos. 31623 / Dist 37". 01 Epoch 1835.10 South. 319 01 33 SO 1836.29 Smyth. CONSTELLATION OF SAGITTARIUS 157 \ CHAPTER IV. DIRECTIONS FOR TRACING THE CONSTELLATIONS ON MAP NO. XVIII. SAGITTARIUS THE ARCHER. SCUTUM SOBIESKI THE SHIELD OF SOBIESKI. Favorably situated for examination in July, August, and September. SAGITTARIUS. THE ARCHER. This is the ninth sign and the tenth constellation of the Zodiac. It is situated next east of Scorpio, with a mean declination of 35 S. or 12 below the ecliptic. The sun enters this sign on the 22d of Novem- ber, but does not reach the constellation before the 7th of December. It occupies a considerable space in the southern hemisphere, and contains a number of subordinate, though very conspicuous stars. The whole num- ber of its visible stars is sixty-nine, including five of the 3d magnitude, and ten of the 4th. It may be readily distinguished by means of five stars of the 3d and 4th magnitudes, forming a figure resembling a little, short, straight-handled Dipper, turned nearly bottom upwards, with the handle to the west, familiarly called the Milk-Dipper, because it is partly in the Milky- Way. This little figure is so conspicuous that it cannot easily be mistaken. It is situated about 33 E. of Antares, and comes to the meridian a few minutes after Lyra, on the 17th of August. Of the four .^ 158 GEOGRAPHY OF THE HEAVENS. stars forming the bowl of the Dipper, the two up- per ones are only 3 apart, and the lower ones 5. The two smaller stars forming the handle, and extending westwardly about 4, and the easternmost one in the bowl of the Dipper, are all of the 4th magnitude. The star in the end of the handle, is marked x, and is placed in the bow of Sagittarius, just within the Milky Way. Lambda may otherwise be known by its being nearly in a line with two other stars about 4^ apart, extending towards the S. E. It is also equidistant from

, and produced about 6 farther to the west, it will point out T, and produced about 3 from tT, it will point out y; stars of the 3d magnitude, in the arrow. The latter is in the point of the arrow, and may be known by means of a small star just above it, on the right. This star is so nearly on the same meridian with Etanin, in the head of Draco, that it culminates only two minutes after it. A few other conspicuous stars in this constellation, forming a variety of geometrical figures, may be easily traced from the map. I TELESCOPIC OBJECTS. A CLUSTER. A. R. = 17 h. 55 m. 01 s. Dec. = 22 30' Near the upper part of the bow of the Archer. It is a coarse cluster of small stars, forming a circular figure. It is 2 S. E. of p. Sagittani Discovered by Messier, 1764. p SAGITTARII. A. R. = 18 h. 04 m. 11 s. Dec. 21 05' 7". A quadruple star on the north end of the Archer's bow. Registered as triple by the elder Herschel. Discovered to be quadruple by his son. A. 3; B. 16; C. 9; D. 10, magnitude. Pos. A B = 260 Dist. 10"0} AC =315 40. C Estimations. A D = 114 5 45.03 A GLOBULAR CLUSTER. A. R. = 18 h. 14 m. 41 s. Dec. 24 56' 9". Discovered by Messier, 1764. Resolved by Sir W. Herschel. It is not very bright, but constitutes a good test for space penetrating power. It is between the Head and Bow of the Archer, and is midway between ft Ophiuchi and ft Lyras. A LOOSE CLUSTER. A. R. = 18 h. 22 m. 14 s. Dec. 19 JO' 2". Between the Archer's head and the shield of Sobeiski. "The gathering portion of the group assumes an arched form, and is thickly strewn in the upper part of the field, where a pretty knot of minute CONSTELLATION OF SAGITTARIUS. 159 glimmerers occupies the center, with much star dust around." It is 5 N. E. of p. Sagittarii. A GLOBULAR CLUSTER. A. R. = 18 h. 26 m. 25 s. Dec. 24 01' 4". In the space between the head and bow of Sagittarius, midway between p and and the Northern Crown on the northwest, may be seen yg and y. two stars of the 3d magnitude, situated in the west shoulder, about 3 apart The north- ernmost of these two are called Rutiltcuft. Those four stars in the shape of a diamond, 8 or 10 southwest of the two in the shoulder of Hercules, are situated in the head of the Serpent. About 12 E. N. E. of Rutilicus, and 10^ directly north of Ras Algethi, are two stars of the 4th magnitude, in the east shoulder. They may be known by two very minute stars a little above them on the left The two stars in each shoulder of Hercules, with Ras Algathi in the head, form a regular triangle. The left, or east arm of Hercules, which grasps the triple-headed monster Cerberus, may be traced by means of three or four stars of the 4th magnitude; situated in a row 3 and 4 apart, extending from the shoulder, in a northeasterly direction. Thai small cluster, situated in a triangular form, about 14 northeast of Ras Algethi, and 13 east- southoast, of the left shoulder, distinguish the head of Cerberus. Eighteen or 20 northeast of the Crown, are four stars of the 3d and 4th magnitudes, marked TT, , > > forming an irregular square, of which the two southern ones are about 4 apart, and in a line 6 or 7 south of the two northern ones, which are nearly 7 apart. Pi, in the northeast corner, may be known by means of one or two other small stars, close by it, on the east. E/a, in the northwest corner, may be known by its being in a row with two smaller stars, extending towards the northwest, and about 4 apart The stars of the 4th mag- nitude, just south of the Dragon's head, point out the left foot and ancle of Hercules. ' Several other stars, of the 3d and 4th magnitudes, may be traced out in this constellation, by reference to the map. TELKSCOPIC OBJECTS. DOUBLE AND BINARY STARS. RAS ALRT.THI or A HERCULIS, A. R. =r 17 h. 07 m. 21 s. Dec. = -f 14O 34' 05". A beautiful double star on the head of Hercules. Dist. = 4".5. Pos. 11 8 08'. The compo- nents are of the magnitudes 3 and 5, the largest star orange, the. smaller one greenish. There is no reason to believe" that these stars are physically united, although the opinion seems to have prevailed among astronomers that such a union would be found to exist among all the colored double stars. Pos. 117036' Dist. 4". 92 Ep. 1847.62 Mitchel. y HKRCTJLTS. A. R. = 16 h. 14 m. 53 s. Dec. =-f 19O 32' 00". A coarse double star on the left arm. ' Dist. 38".7. Pos. 242O 03'. A 3 white, B 10 lilac. No change in distance or position has been detected, except what may be imputed to errors of observation. *<"' CONSTELLATION OF HERCULES. 163 but this should be true, also, of the central s,tar, and when the nebula brightens up under the eye, the star should increase in brilliancy in the like proportion. In case we abandon the nebular hypothesis, this object, and one or two others of like character, become utterly inexplicable. If we say that each particle of nebulous light is a sun or star, and that the mass of hazy light, so uniform in its brightness, is but the clustering of millions of suns in a flat annulus. how stupendous must be the size of that lucid point which occupies the center of this wonderful object, and is so distinctly revealed by the telescope 1 The old idea of a mighty predominant cen- tral globe would, on such an hypothesis, seem to be well founded, for it would require millions of nebulous points to constitute a blaze of light equal to this central star. This object is found on the tip of the pre- ceding wing of the Swan, and 5 north of eT Cygni. A LOOSE SMALL CLUSTER A. R. = 20 h. 18 m. 17 s. Dec, -}- 370 59' 09". Discovered by Messier, 1764. Near the root of the Swan's neck I counted but twenty stars in the field oi view, July, 1847, and these were much scattered. P J70 GEOGRAPHY OF THE HEAVENS. A SMALL CLUSTER, on RICH FIELD. A. R. = 21 h. 26 m. 29 s. Dec. -\- 47 43' 08". It is between the Swan's tail and the Lizard. Many other clusters and nebulae will be found on the chart, from which their places in the heavens may be readily found. LYRA. THE HARP. This constellation is distinguished by one of the most brilliant stars in the northern hem- isphere. It is situated directly south of the first coil of Draco, between the Swan, on the east, and Hercules, on the west ; and, when on the meridian, is almost directly overhead. It contains twenty-one stars, including one of the 1st magnitude, two of the 3d, and as many of the 4th. " There Lyra, for the brightness of her stars, More than their number, eminent ; thrice seven She counts, and one of these illuminates The heavens far round, blazing imperial, In the first order." This star, of " the first order, blazing with impe- rial " luster, is called Vega, marked a, and sometimes Wega ; but more frequently it is called Lyra, after the name of the constellation. There is no possibility of mistaking this star for any other. It is situated 14f S. E. of 7 Draconis. It may be certainly known by means of two small, yet conspicuous stars, of the 5th and 6th magnitude, situated about 2 apart, on the east of it, and making with it a beautiful little triangle, with the angular point at Lyra. The northernmost of these two small stars is marked , and the south- ern one, . About 2 S. E. of ", and in a line with Lyra, is a star of the 4th magnitude, marked B C 76 1 .576 1847.60 Mitchel. The object may be found between the Eagle's wing and the left heel of Antinous. A TRIPLE STAR. A. R. =19 h. 28 m. 01 s. Dec. = 10 46' U8". On the right knee of Antinous. A 9, B 10, C 12, magnitudes. Pos. A B 338 04' Dis. 3".02 Epoch 1835.58 Smyth. A C 153 05 8 .00 " A B 319 04 2 .54 1847.60 Mitchel. 169 17 Some suspicion exists with reference to the possible binary character of the set. A DOUBLE STAR. A. R. 18 h. 57 m. 59 s. Dec. -f- 6 18' 08", on the edge of the Eagle's wing. A ?, B 9 magnitude. Pos. 154038' Dis. 10". 1 33 Epoch 1831.70 Striive. * 152 28 9 .492 1847.65 Mitchel. A SMALL AWU LOOSE CLUSTER. A. R. 19 h. 08 m. 36 s. Dec. 1 IT 09", between the lower wing of the Eagle and the thigh of An- tinous, consisting of fifteen or twenty stars, with indications of star-dust. Examined 16th July, 1847. A STELLAR NEBULA. A. R. = 19 h. 23 m. 55 s. Dec. -{- 8 54' 01", on the Eagle's back, 5 east of Altair, or a. Aquilae. Discovered by Sir W. Herschel, and estimated at the 900th order of distances. Examined on the 16th July, 1847. The object is very small, brightening at a vertex, and running off in the shape of a fan. Several stars in the field ; a bright one above, and one below the nebula. Sir John Herschel says, " It is like a nebula well resolved, and is a curious object." A DELICATE DOUBLE STAR. A. R. = 19 h. 35 m. 02 s. Dec. = 8 00' 05", on the Eagle's back, 2 east of Altair, and a little south of the parallel. A 7, B 9^ magnitude. Pos. 2520 32' Dis. 32". 12 Epoch 1825.52 Striive. v AQ.UILK. A. R. = 19 h. 41 m. 10 s. Dec. = -f- 1 1<> 25' 04". A close double star, near the northern wing of Aquilae. A 6, B 7 mag. Pos. 122 00' Dis. 1".50 Epoch 1831.70 Smyth. 123 09 1 .20 1847.66 MitcheL CONSTELLATION OF AQUILA ET ANTINOUS. 177 A AHUIL*:. A. R. = 19 h. 42 m. 58 s. Dec. = -f- 8 26' 09" A first magnitude star, with a 10th magnitude companion, suspected to be physically united, Pos. 334044' Dis. 143".40 Epoch 178156 Herschel. 326 06 ' 153 .71 " 1821.85 Striive. 323 06 152 .60 " 1834.81 Smith. The change may be due to a difference of proper motion in the two stars. The annual proper motion of Altair has been fixed at rather more than half a second in A. R., and about one third of a second in declination. 23 AQ.UIL*. A. R. = 19 h. 10 m. 24 s. Dec. = -j- 48' 00". A dose double star, under the Eagle's southern wing. Discovered by Herschel, who appears to have made a mistake in en- tering his measures. His position is 162, distance 3".oO, epoch 1781.58. The Bedford Catalogue marks the position more than 180 dif- ferent, arid thinks Herschel wrote south for north, in recording his observations. This star was carefully measured on the 4th of August, 1847, and gave these results: Pos. 12 09' Dis. 3".57. Bedford Cat. Pos. = 12 06' Dis. 3".l Epoch 1833.68. A DOUBLE STAK. A. R. = 19 h. 37 m. 21 s. Dec. -j- 10 23' 06", on the Eagle's head. A 8, B 10 magnitude. Pos. 2780 18' Dis. 3".00 Epoch 1783.60 Herschel. 276 27 3 .99 1825.56 South. 276 30 4 .00 1836.76 Smyth. 276 36 4 .33 1847.72 Mitchel. The distance between the components seems to be on the increase, while the angle of position remains nearly if not quite the same. DELPHINUS. THE DOLPHIN. This beautiful little cluster of stars is situated 13 or 14 northeast of the Eagle. It consists of eighteen stars, including two of the 3d magnitude, and three of the 4th, but none larger. It is easily distinguished from all others, by means of four principal stars in the head, which are so arranged as to form the figure of a diamond, point- ing northeast and southwest. To many, this clus- ter is known by the name of Job's Coffin; but from whom, or from what fancy, it first obtained this appellation, is not known. 178 GEOGRAPHY OF TEE HEAVENS. There is a star of the 4th magnitude, situated in the body of the Dolphin, about 3 southwest of the Diamond, and marked Epsilon. The other four are marked A/p/ia, Beta, Gamma, and Delta. Between these are several smaller stars, too small to be seen in presence of the moon. The mean declination of the Dolphin is about 15 north. It comes to the meridian the same moment with Deneb Cygni, and about 50 minutes after Altair, on the 16th of September. " Thee I behold, majestic Cygnus, On the marge dancing of the heavenly sea, Arion's friend ; eighteen thy stars appear One telescopic." TELESCOPIC OBJECTS. A PLANETARY NEBULA. A. R. = 20 h. 15 m. 15 s. Dec. 19 36' 06". Between the Dolphin's pectoral fin and the arrow's head. Discovered by Sir William Herschei, 1782. This is a large though faint planetary nebula, the surface being evenly illuminated, ^ir John Herschei suggests that the minute stars in close proximity to the nebula, may be satellites. He remarks " that the enormous magnitude of their bodies, and consequent probable mass (if they be not hollow shells) ; may give them a gravitating energy, which, however large we may conceive them to be 1 , may yet be capable of retain- ing in orbits three or four times their own diameter, and in periods of great length, small bodies of stellar character." Should this suggestion ever be verified, we might be led to attribute eome of the anomalous motions (as yet unaccounted for), among some of the fixed stars, to the disturbing influence of an invisible body of this character. In case any such faint body were situated near Sirius, for example, the brilliancy of this star would entirely hide the nebula. Arti- ficial occultation may detect some of these unknown objects. A SMALL CLUSTER. A. R. = 20 h. 26 m. 21 s. Dec. -f- 06 53', near the Dolphin's tail. Discovered by Sir W. Herschei, 1785. It is a mass of small stars, with several larger stars in the field. $ DELPHIXI. A. R. 20 h. 30 m. 03 s. Dec. -\- 14 02' 06". A delicate triple star, in the Dolphin's body. A 4, B 1 2, magnitude. The minute star B, was added to the previously discovered pair by Sir John Herschei. It had escaped his father and Striive. Pos. A B 1050 00' Dis. 15".() Epoch 1734.79 A C 341 08 30 .0 " CONSTELLATION OF DELPHINUS. 179 y DKLPHINI A. R. 20 h. 39 m. 15 s. Dec. -f- 15O 33' 02". A beautiful double star on the Dolphin's head. A 4, yellow ; B 7, light green. J\o change has been detected. Pos. 2730 03' 00" Dis. 12".0 Epoch 1830. VULPECULA ET ANSER. THE Fox AND THE GOOSE. This is a modern con- stellation, introduced by Hevelius, into a space between the Arrow and the Swan. " I wished," remarked Hevelius, " to place a Fox with a Goose in this space of sky well fitted to it, because such an animal is very cunning, voracious, and fierce. Aquila and Vultur are of the same nature, rapa- cious and greedy." In 1672, while examining this new constellation, Hevelius discovered a star in the head of the Fox, which he had never before seen. This star remained visible for the space of about two years, after which period it disappeared, and has never since been recognized. This nevv constellation has been pretty fairly adopted by astronomers, and may now be said to be pretty firmly fixed in the heavens. Its author counted 27 stars within its limits. The number has been successively increased by later astrono- mers, until finally, Bode has fixed the places of 126 stars in this small space. *.!.S r * The intrusions or additions of Hevelius to the old constellations have been better received by astronomers than those of any other modern inno- vator, probably because his constellations were placed where they seemed to be actually required for convenience of reference. TELESCOPIC OBJECTS. A DELICATE DOUBLE STAR. A. R. = 29 h. 00 m. 10 s. De^ -j- 20 38' 07". Close to the Arrow, under the Fox's shoulder. A 8 B 10, magnitude. Discovered by Sir James South in 1828. Pos. 340 05 Dis. 5".5 Epoch 1839.70 l&O GEOGRAPHY OF THE HEAVENS. A SMALL DOUBLE STAR A. R. 20 h. 15 m. 47 s. Dec. = -f- 23 34' 02". On the Fox's loins. A 8, B 14, indigo blue. About a minute of time preceding this object, and 20' south of it, is a minute close double star, discovered by Struve, and is No. 2672 of his great catalogue. DUMB-BELL NEBULA. A. R. 19 h. 52 m. 39 s. Dec. 22 17' 01". Discovered by Messier, 1764. This is one of the large and magnificent nebulae, located in one of the richest parts of the heavens. As first seen, it resembled two balls joined together like a dumb-bell, or double headed shot, and hence its name. As more powerful instruments have been directed to its exam- ination, its form has become more wonderful and mysterious. The drawing represents this object as seen with the Cincinnati Refractor, July, 1847, at which time it was described while under the eye, as follows : " The shape of the nebula is an oval or ellipse, whose larger axis occupies four-fifths of the field of view, with a power of 250. The figure imperfect to the left of the lower vertex. The right hand ball of light rather the largest, the round figure being broken by two blunt points. 7'he upper star is seen a little outside the outline. The left hand mass of light takes the same form as that on the right, only the light does not extend up or down quite as far. At each extremity a star is located. The vertices of the great or general outline comparatively faint. Several stars are visible on the nebula. One distinctly seen in the center of the right hand mass of light, one in the center of the principal axis, fainter than the first mentioned ; one still more faint midway between these two. Another is seen by glimpses below, and to the right of the one first mentioned. There are besides many stars in the same field of view." Lord Rosse's great telescope has produced no great change in the figure, while it has revealed more light in the compressed parts of the nebula. Nichol describes it as having " no longer distinctness of com- pletion of form, but a strange mass internally most irregular, cluster- ing apparently around two principal nuclei, or knots of stars, and pre- senting, where it merges into the dark, the utmost indehniteuess of outline," and yet the figure has an outline quite as well defined as those usually presented in drawings of this object. I his object is doubtless the union of two mighty clusters of myriads of suns, and as the double stars are scattered profusely through space, we occasionally find what may be justly termed double nebulae and double clusters. The distance of this object must be absolutely over- whelming, and its dimensions beyond the powers of computation. It may be picked up on a line joining f& Cygni and the Dolphin, and about 7 southeast of the first named star. The angle of position of the line joining the centers of the nebulous masses, is 31 08', as measured by Capt Smyth. SERPENT ARIUS, VEL OPHIUCUS. 181 ;!^';;- * 'v##P**& DIRECTIONS FOR TRACING THE CONSTELLATION ON MAP NO. XXII. SERPENTARIUS, VEL OPHIUCHUS THE SERPENT-BEARER. Favorably situated for examination in June, July, and August. SERPENTARIUS, VEL OPHIUCUS. THE SERPENT-BEARER is also called JEsculapius, or tfye god of medicine. He is represented as a man having both hands clenched in the folds of a prodigious serpent, which is writhing in his grasp. The constellation occupies a considerable space in the mid heavens, directly south of. Hercules, and west of Taurus Poniatowski. Its center is very nearly over the equator, opposite to Orion, and comes to the meridian the 26th of July. It con- tains seventy-four stars, including one of the 2d magnitude, five of the 3d, and ten of the 4th. The principal star in Serpentarius is called Has Alhague, marked a. It is of the 2d magnitude, and situated in the head, about 5 east-southeast of Ras Algethi, marked a, in the head of Hercules. Ras Alhague is nearly 13 north of the equinoctial, while Rho y in the southern foot, is about 25 south of the equinoctial. These two stars serve to point out the extent of the constellation from north to south. Ras Alhague comes to the meridian on the 28th of July, about 21 minutes after Ras Algethi. About 10 southwest of Ras Alhague are two small stars, one of the 3d, the other of the 4th magnitude, scarcely more than a degree apart. They distinguish the left or west shoulder. The northern one is marked Iota, and the other Kappa. Eleven or twelve degrees south-southeast of Ras Alhague, are two other stars of the 3d magnitude, in the east shoulder, and about 2 apart. The upper one is called Cheleb, or , and the lower one Gamma. Q 182 GEOGRAPHY OF THE HEAVENS. These stars in the head and shoulders of Serpentarius form a triangle, with the vertex in Ras Alhague, and pointing towards the northeast. About 4 east of r , is a remarkable cluster of four or five stars, in the form of the letter V, with the open part to the north. It very much resembles the Hyades. This beautiful little group marks the face of TAURUS PONIATOWSKI. The solstitial colure passes through the equinoctial about 2 east of the lower star in the vertex of the V. The letter name of this star is k. There is something remarkable in its central position. It is situated almost exactly in the mid heavens, being nearly equidistant from the poles, and midway between the vernal and autumnal equinoxes. It is, how- ever, about one and a third degrees nearer the north than the south pole, and about two degrees nearer the autumnal than the vernal equinox, being about two degrees west of the solstitial colure. Directly south of the V, at the distance of about 12, are two very small stars, about 2 apart, situated in the right hand, where it grasps the serpent. About halfway between, and nearly in a line with the two in the hand and the two in the shoulder, is another star of the 3d magnitude, marked Ztta, situated in the Serpent, opposite the right elbow. It may be known by means of a minute star just under it. Marsic, marked A, in the left arm, is a star of the 4th magnitude, about 10 southwest of / and x . About 7 farther in the same direc- tion, are two stars of the 3d magnitude, situated near the hand, and a little more than a degree apart. The upper one of the two, which is about 1 6 north of Graffias in Scorpio, is called Yed, marked ef, the other is marked s . These two stars mark the other point in the folds of the monster where it is grasped by Serpentarius. The left arm of Serpentarius may be easily traced by means of the two stars in the shoulder, the one (x) near the elbow, and the other two in the hand ; all lying nearly in a line north-northeast, and south- southwest. In the same manner may the right arm be traced, by stars very similarly situated ; that is to say, first by the two in the east shoulder, just west of the V, thence 8 in a southerly direction inclin- ing a little to the east, by (known by a little star right under it), and then by the two small ones in the right hand, situated about 6 below About 12 from Antares, in an easterly direction, are two stars in the right foot, about 2 apart. The largest and lower of the two, is on the left hand. It is of between the 3d and 4th magnitudes, and marked p . There are several other stars in this constellation, of the 3d and 4th magnitudes. They may be traced out from the maps. SERPENTARIUS, VEL OPHIUCHUS. 183 TELESCOPIC OBJECTS. /> OPHIUCHI. A. R. = 16 h. 16 m. 00 s. Dec. = 23O 04' 03". A fine double star, on the Serpent Bearer's foot. A 5, B 7 magnitude. Pos. 3 01' Dis. 3".08 Epoch 1832.38 Discovered by Sir W. Herschel, 1 780. There is but little evidence of any physical connection between the components. *. OPHIUCHI, a binary star. A- R. = 16 h. 22 m. 51 s. Dec. -f- 2 20' 04". A 4, B 6, magnitude. The following measures are recorded : Pos. 75030' Dis. 0".50 Epoch 1783.18 Herschel. 331 48 0.84 1825.51 Struve, 356 05 1 .00 1839.67 Smyth. 2 47 8" 1 .29 1841.59 Madler. 3 42 1 .42 1847.65 Mitchel. From these observations, it is evident that the stars are revolving about their common center of gravity, in a period of about 120 years. T OPHIUCHI. A. R. = 17 h. 54 m. 22 s. Dec. = 8 10' 04". A very close binary star, on the right hand of Ophiuchus, the closest of Herschel's double stars. Discovered, April, 1783. A 5, B 6, magnitude. A third star, dis- tant 83", in the same field of view. The following measures will exhibit the progressive changes : Pos. 3310 36' Dis. elongated Epoch 1783.27 Herschel. 199 54 0".436 1836.62 Struve. 225 36 .772 1842.57 Mildler. 229 24 .779. 1846.51 Mitchel. Miidler remarks, with reference to this system, as follows : The pe- riodic time must be about 110 years. The inclination and eccentricity appear to be considerable. The distance was a minimum in 1825, or a short time before. It has regularly increased ever since. It is hoped that observations further south than Derpat may follow this binary sys- tem with attention." Combining all the observations, a shorter period seems to be indicated, perhaps not exceeding 90 years. The yearly change in the angle of position, from 1827 to 1846, amounts to 4O 33'. 70, or p OPHIUCHI. A. R. = 17h.57m. 22s. Dec. = -f- 2O 32' 06" A swiftly revolving binary system. A 4, B 7, magnitude. This star has engaged the attention of many distinguished astrono- mers. The rapidity of its motion excited the notice of its discoverer, and caused the following record : " The alteration of the angle of posi- tion that has taken place in the angle of position of this double star is remarkable. October 7, 1779, the stars were exactly in the same paral- lel, the preceding star being largest. September 24, 1781, it was 9 14', n f ; and, May 29, 1804, it was 48 01', n p; which gives a change of 131 59', in 24 years and 254 days." The orbit has been computed by several astronomers; but with the greatest care, recently, by M. Miidler, who has reached the extraordinary conclusion, that these re- 184 GEOGRAPHY OF THE HEAVENS. volving stars are moving under the disturbing influences of some third body, as yet undiscovered. Midler's elements are the following : Periastre passage, T = 1812.73 Periodic time, P == 92.869 years. The angle between the maj. axis and line of nodes, . >,- . *# \ = 142 05' 08" Eccentricity, - - e = 0.4438 Mean annual angle of motion, m = 232.584 Angle of position, - ^ = 126 47 02 Inclination of the plane of the orbit, t== 64 51 04 The following measures will show the changes which have occurred Pos. 90 00' Dis. 3". 59 Epoch 1779.77 Herschel. 157 86 3 .79 1821.74 Striive. 137 20 5 .53 1830.57 Dawes. 178 54 6 .44 1837.52 Bessel. 175 26 6 .38 1841.53- Midler. 120 45 6 .53 1847.55 Mitchel. The discrepances between computation and observation, ascribed by Miidter to the influence of some unknown disturbing body, have been recently attributed to aberration, produced by the motion of the stars in their orbits. This matter is yet in a state of uncertainty. There are many double stars in this constellation, which will be readily found on the charts, distinguished, as usual, by their round furm, all other stars being angular, or star-shaped. Under favorable circumstances, all stars appear round, and disk-like, in large and perfect instruments. A RICH GLOBULAR CLUSTER. A. R. = 16h. 38m. 56s. Dec. = _ 10 40' 03". This object' I have repeatedly examined. It nearly fills the field of view, with a power of 250, its diameter being from 7 to 8 minutes of space. There are three bright stars in the cluster, with many smaller but prominent ones scattered in the field. Messier discovered it, in 1764, but saw no stars. Herschel locates it at the distance 186. It may be found nearly on the line joining i and & and 8$ distant from the first star. It is represented in the Bedford Catalogue as greatly condensed at the center. I find this remark scarcely applicable to its appearance, as seen with the 12 inch refractor. The resolution is complete. A CLUSTER OF COMPRESSED STARS. A. R. = 16 h. 48 m. 45s. Dec. = 3 51' 08". Discovered by Messier, 1764, and by him de- scribed as a beautiful round nebula. It is easily resolved, and, under a full aperture of 12 inches, is a noble object. There are three pretty dis- tinct star-like radiations, running out from the center, and four or five little patches of separate stars in the same field of view. It follows Ophiuchi, on the same parallel nearly, and about 8 distant. Sir W Herschel makes its profundity of the 243d order. A LAROI GLOBULAR CLUSTER. A. R. = 17 h. 29 m. 13 s. Dec. __ 30 00' 09". Sir William Herschel describes this object as follows : SERPENTARIUS, VEL OPHIUCUS. 185 " Extremely bright, round, easily resolvable. With a power of 500, I can see the stars. The heavens are pretty rich in stars of a certain size, but they are larger than those in the cluster, and easily to be distinguished from them. This cluster is considerably behind the scattered stars, as some of them are projected on it. From the observations of the 20 feet telescope, which had the power of discerning objects 75.08 times as far as the eye, the profundity of this cluster must be of the 900th order." This cluster may be found 6 south by west from y Ophiuchi, nearly midway from /3 Scorpii and the tail of Aquila. It is a fine object, large and well defined. A LARGE AND EASILY RESOLVED CLUSTER. A. R. = 17h. 47m. 32 s. Dec. = 18 58' 02", between the left leg of Ophiuchus and the bow of Sagittarius. Discovered by Messier, 1 764. It is on a line northwest from p. Sa- gittarii, and distant about 5. A CLOSE DOUBLE STAR. A. R. 16 h. 54 m, 18 s. Dec. = -\- 8 41' 03". On the right shoulder. A 7, B 8. Pos. 135040' Dis. 1".34 Epoch 1830.97 Striive. 137 00 1 .50 1832.41 Smyth. 146 57 .826 1847.70 Mitchel. These last measures would indicate binary character, and I am con fident that they were well made. 36 OPHIUCHI. A. R. = 17 h. 05 m, 29 s. Dec. = 26 21' 05* A double, or rather, multiple, star, between the left foot and the Scor pion's tail. A 4^, B 6, magnitude. Pos. 213020 Dis. 5".32 Epoch 1843.52 Airy. 215 49 4 .27 1847.62 Mitchel. 73 OPHIUCHI, A. R. = 18 h. 01 m. 37 s. Dec. = -f- 30 58' 03" Between the left shoulder of Ophiuchus and the Serpent's tail. A 6, B 7, magnitude. Discovered by Herschel. Pos. 2670 12' Dis. 0".90 Epoch 1783.32 Herschel. 257 37 1 .98 1822.46 Her. & South. 259 44 1 .54 1831.05 Struve. 255 00 . 1 .40 1842.00 Smyth. 253 00 1 .274 1847.55 Mitchel. Here is certainly a binary system. The early measures of Sir W. Herschel, as well as those by Herschel and South, are discordant with the later measures. From 1831 to 1847, a period of 16 years, there has been a change of 6. The motion is retrograde. A DOUBLE STAR. A. R. = 17 h. 17 m. 21 s. Dec. = -j- 15O 45' 04". Between the heads of Ophiuchus and Hercules. A 7, B 13. Discovered by Struve. Pos. 610 54' Dig. 4 <0 73 Epoch 1830.23 Struve. 62 33 3 .654 1847.60 Mitchel. These observations imply fixity in this set. 186 GEOGRAPHY OF THE HEAVENS. 88 P. XIV, OPHIUCHI. A. R. = 16 h. 20 m. 10s. Dec. = 7 45' 09". A delicate double star, near the right thigh of Ophiuehus. A 7, B 12. Reckoned a difficult object, from the small size of B. Pos. 302 44' Dis. 4" .687 Epoch 1831.48 Striive. 305 00 5 .000 1833.47 Smvth. 304 14 5 .292 1817.70 L. M. There is strong evidence of fixity in these measures, and there is little reason to believe that these stars are otherwise than optically related. DIRECTIONS FOR TRACING THE CONSTELLATIONS ON MAP NO. XXIII. PEGASUS THE FLYING HORSE. EQUULUS THE HORSE'S HEAD. Favorably situated for examination in September, Oc- tober, November and December. PEGASUS. THE FLYING HORSE. This constellation is repre- sented in an inverted posture, with wings. It occu- pies a large space in the heavens, between the Swan, the Dolphin and the Eagle, on the west; and the Northern Fish and Andromeda, on the east. Its mean right ascension is 340, or, it is situated 20 W. of the prime meridian. It extends from the equinoctial N. 35. Its mean length, E. and W., is about 40, and it is six weeks in passing our meri- dian, viz. from the 1st of October to the 10th of November. We see but a part of Pegasus, the rest of the ani- mal being, as the poets imagined, hid in the clouds. It is readily distinguished from all other constel- lations by means of four remarkable stars, about 15 apart, forming the figure of a square, called the square of Pegasus. The two western stars in this square *come to the meridian about the 23d of CONSTELLATION OF PEGASUS. 187 October, and are about 13 apart. The northern one, which is the brightest of three triangular stare in the martingale, is of the second magnitude, and is called Scheat, marked 0. Its declination is 26f N. Markab, marked a, also of the second magnitude, situated in the head of the wing, is 13 S. of Scheat, and passes the meridian 11 minutes after it. The two stars which form the eastern side of the square, come to the meridian about an hour after those in the western. The northern one has al- ready been described as Alpheratz, or a, in the head of Andromeda ; but it also belongs to this constel- lation, and is 14 E. of Scheat. 14 S. of Alphe- ratz, is Algenib, a Persei (see Map No. I), the last star in the wing, situated 6 E. of Markab. Algenib, in Pegasus, Alpheratz, in Andromeda, and Caph, in Cas- siopeia, are situated on the prime meridian, and point out its direction through the pole. For this reason, they are sometimes called the three guides. They form an arc of that great circle in the heavens from which the distances of all the heavenly bodies are measured. It is an arc of the equinoctial colure, which passes through the vernal equinox, and which the sun crosses about the 21st of March. It is, in astronomy, what the meridian of Greenwich is in geography. If the sun, or a planet, or a star, be said to have so many degrees of right ascension, it means that the sun or planet has ascended so many degrees from this prime meridian. Enif, marked , sometimes called Enir, is a star of the third magni- tude, in the nose of Pegasus, about 20 W. S. W. of Markab, and half way between it and the Dolphin. About one-third of the distance from Markab towards Enif, but a little to the S. there is a star of the 3d mag- nitude, in the neck, whose letter name is Zeta. The loose cluster di- rectly S. of a line joining Enif and Zeta, forms the head of Pegasus. In this constellation, there are eighty-nine stars visible to the naked eye, of which three are of the second magnitude, and three of the third. TELESCOPIC OBJECTS. A DOUBLE STAR. A. R. = 21 h. 14 m. 41 s. Dec. = 19 o or 04", between the head of Pegasus and the hind legs of the Fox. A 4, considered variable ; B 9, magnitude. Pos. 310008' Dis. 36".4 Epoch 1333.95 188 GEOGRAPHY OF THE HEAVENS. Although no sensible change has yet been discovered in this set, a common proper motion would indicate some physical union. A LARGE AWD BRILLIANT CLUSTER. A. R. = 21 h. 22 m. 13s. Dec. = -{- 1 10 27' 04", between the mouths of Pegasus and Equulus. Discovered by Meraldi, 1745, and described by him as " a nebulous star, quite bright, and composed of several stars." It was fully resolved by Sir William Herschel, 1783, and placed by him in the 243d order of distances. This object is greatly condensed at the center, and has many radiations. There is a great condensation at the center, and even a brilliant nucleus, around which the stars are scattered in rich profusion for a distance of about 2' in diameter. Beyond this the cluster is less rich in stars. The space preceding the cluster is nearly vacant. The follow- ing space is tolerably well filled with stars. A SMALL DOUBLE STAR. A. R. = 22 h. 06 m 37 s. Dec. = -f- 160 24' 02", between the head and legs of Pegasus. A 7, B lO^. The first yellow, the second green. Discovered by Striive. Pos. 316 24' Dis. 7".63 Epoch 1828.95 Striive. 331 29 8 .03 1847.65 Milchel. This is certainly a binary system. 37 PEGASI.A. R. = 22 h. 21 m. 53 s. Dec. = -f 03 37' 03", a binary star on the mane and near the head of Pegasus. A 6, B 7. Discovered by Striive. Pos. 112 36' Dis. 1".36 Epoch 1831.12 Struve. 118 54 I .10 1839.66 Smyth. 121 46 .98 1847.70 Mitchel. Here is strong evidence of binary character, as the angular velocity has been on the increase, and the distance is certainly diminishing. 55 H. L, PEGASI. A. R. = 22 h. 56 m. 58 s. Dec. = -J- 11 27' 09", an elongated nebula in the Horse's mane. Discovered by Herschel in 1784. This is an exceedingly faint and difficult object. I examined it care- fully in September, 1847, and although it was readily found, it required very close gazing to make any thing out of it. It stretches between two stars, the upper one of which is not touched by the nebulous matter. A minute telescopic star just precedes the upper extremity of the nebu- lous matter, which seems to have been overlooked by preceding observ- ers. There is something of a glow at the center after long gazing, and under a side glance. This object is thought to be a flat ring seen obliquely. It is one of the most difficult objects in the heavens, and requires a powerful instru- ment for satisfactory examination. EQUULUS, VEL EQUI SECTIO. 189 EQUULUS, VEL EQUI SECTIO. THE LITTLE HORSE, OR THE HORSE'S HEAD. This Asterism, or small cluster of stars, is situated about 7 west of Enif, in the head of Pegasus, and about halfway between it and the Dolphin. It is on the meridian at 8 o'clock on the llth of October. It contains ten stars, of which the two principal are only of the 4th magnitude. These may be readily distinguished by means of the long irregular square which they form. The two in the nose, are much nearer together than the two in the eyes; the former being 1 apart, and the latter 2?. Those in the nose are uppermost, being 4 north of those in the eyes. This figure also is in an inverted posi- tion. These four stars are situated 10 or Ii2 southeast of the diamond in the Dolphin's head. Both of these clusters are noticeable on account of their figure rather than their brilliancy. TELESCOPIC OBJECTS. 376 P. XX, EQ.UULEI.P A. R. = 20 h. 47 m.' 40 s. Dec. = -j- 03 55' 06", a close double star between the Horse's head and the bow of A ruinous. A 6, B 8, magnitude. Discovered by Struve. Pos. 289 10' Dis. 1".8 Epoch 1829.48 Struve. . 287 45 + 1 .874 1847.65 Mitchel. These measures may possibly indicate a slow retrograde motion, a change of 2 about in 18 years. This would give an annus magnus to the system of more than 4000 years. A. R. = 20 h. 51 m. 05 s. Dec. = 03 41' 01", a delicate triple star, preceding the Horse's forehead. A 5^, B 7. Discovered to be double by Herschel ; subdivided by Struve. Pos. A B 290 00' Dis. 0".50 Epoch 1838.83 Smyth. 288 06 .574 1847.60 Mitchel. AC 84 21 9 .37 1780.59 Herschel. 79 21 12 .37 1823.58 Her. & South. 78 01 11 .20 1838.83 Smyth. 76 25 It .08 1847.60 Mitchel. These measures determine the binary character of A and C, which is likewise rendered more certain by the equality of their proper motion. 190 GEOGRAPHY OF THE HEAVENS. Here we are presented with a magnificent system. Three suns revolv- ing about their common center of gravity, and sweeping, together with their trains of planets and comets, through the regions of space. A EQ.UULEI. A. R. = 20 h. 54 rn. 19 s. Dec. = -f- 06 33' 03". A fine double star preceding the Horse's nose. A 6, B 6^, magnitude. Discovered by Striive. Pos. 2250 36' Dis. 2".6 Epoch 1833.72 Smyth. 227 42 I .9 1847.60 Mitchel. These observations are not sufficient to determine the binary character. DIRECTIONS FOR TRACING THE CONSTELLATIONS ON MAP NO. XXIV. AQUARIUS THE WATER-BEARER. CAPRICORNUS THE GOAT. Favorably situated for examination in September, October, November and December. AQUARIUS. THE WATER-BEARER. This constellation is rep- resented by the figure of a man, pouring out water from an urn. It is situated in the Zodiac, immedi- ately south of the equinoctial, and bounded by the Little Horse, Pegasus, and the Western Fish on the north, the Whale on the east, the southern Fish on the south, and the Goat on the west. It is now the 12th in order, or last of the Zodiacal constella- tions ; and is the name of the llth sign in the ecliptic. Its mean declination is 14 south, and its mean right ascension 335, or 22 hours, 20 min.; it being 1 hour and 40 min. west of the equinoctial colure ; its center is, therefore, on the meridian the 15th of October. It contains one hundred and eight stars ; of which toe four largest are all of the 3d magnitude. CONSTELLATION OF AQUARIUS* ^ f 191 " His head, his shoulders, and his lucid breast, Glisten with stars ; and where his urn inclines, Rivers of light brighten the wat'ry track." The northeastern limit of Aquarius may be readily distinguished by means of three stars of the 4th, and one of the 5th magnitude, in the hand and handle of the urn, so placed as to form the letter Y, very plainly to be seen, 15 southeast of Enif, or * Equulei, or 18 S. S. W. of Markab, in Pegasus ; making with the two latter nearly a right angle. About 4 west of this figure is El Melik, marked a., a star of the 3d magnitude, in the east shoulder, and the principal one in this con- stellation. 10 southwest of a., is another star of the same magnitude, situated in the west shoulder, called Sad es Saud, marked @. Ancha, marked 6, of the 5th magnitude, is in the right side, 8 south of A. 9 east of 6, is another star of the 4th magnitude, whose letter name is Lambda. Scheat, marked cf, of the 3d magnitude, lying below the knee, is situated 8^ south of x; and 14 south of f, the brilliant star Fomalhaut, of the 1st magnitude, terminates the cascade in the mouth of the Southern Fish. This star is common to both these constsellations, and is one of those from which the lunar distance is computed for ascer- taining the longitude at sea. It culminates at 9 o'clock on the 22d of October. Fomalhaut, Deneb Kaitos, and Alpha in the head of Phoenix, make a large triangle, whose vertex is in Deneb Kaitos. Those two stars of the 4th magnitude, situated 4 south of @, and nearly the same distance from 6 , are in the tail of Capricorn. They are about 2 apart. The western one is called Deneb Algedi. The rest of the stars in the cascade are quite small ; they may be traced from the letter Y, in the urn, in a southeasterly direction towards the tail of Cetus, from which the cascade suddenly bends off near eF, in an opposite course, and finally disappears in the mouth of the South- ern Fish, 30 south of Y. TELESCOPIC OBJECTS. 4 AauARii. A. R. = 20 h. 42 m. 57 s. Dec. = 6 13' 02". - A close binary star, between Aquarius and Equuleus. A 6, yellow ; B 8, purple. Discovered by Sir W. Herschel. The following measures are the only ones which I have been able to find. Pos. 3510 30' Dis. 00".30 Epoch 1782.68 Herschel. 25 07 00 .81 1825.59 Struve. 24 36 00 .6 1841.51 Mitdler. Vf 192 ' -fr GEOGRAPHY OF THE HEAVENS. A PLANETARY NEBULA. A. R. = 20 h. 55 m. 27 s. Dec. = 110 59' 00". i n ^ middle of the Scarf of Aquarius. It maybe found nearly on the parallel of <* Capricorni, and 12 east of it. Discovered by Sir William Herschel in 1782. Its diameter amounts to no less than 20". The surface evenly tinted and of a delicate pale blue. Its disk is comparatively well defined, and the tint resembles that of Uranus and Neptune. Its distance must be equal to that of the fixed stars, as it has no annual parallax. Its diameter, therefore, cannot be less than three thousand millions of miles. I have frequently examined this wonderful object, and on the 9th of September, 1847, found its diameter to be about 9" or 10". The upper part ia wanting in roundness, giving it the appearance of an obtuse crescent 12 AQ.UARII A. R. = 20 h. 55 m/37 s. Dec, = 06 27' 00". A close double star in the space between the Scarf of Aquarius, and the head of Equuleus. A 5, white ; B 8, light blue. Discovered by Striive. Pos. 1890 36' Dis. 02".66 Epoch 1831.31 Striive. 191 00 02 .80 1831.82 Smyth. 191 30 08 .23 1847.63 Mitchel. There is something extraordinary about this star. The distance obtained by my measures is nearly four tirm s as great as that in the books ; and the star B instead of being of the 8 magnitude, is certainly as low as the 15th. I satisfied myself of this by turning the instrument on yg Aquarii, whose companion is of the 15th magnitude. The star may be variable, but the increase of distance is unaccountable. AauABiT A. R. = 21 h. 23 rn. 07. Dec. = 06O 16' 00", on the right shoulder of Aquarius. A 3, yellow ; B 15, blue. Discovered by Herschel, who gave the Pos. 325 48' Dis. uncertain. Epoch 1 782 370 00 02".00 1833 Smyth. This last is a mere estimation. : f !,. 29 AQ.UARII. A. R. = 21 h. 53 m. 41 s. Dec. = 17 43* 09". A beautiful double star on the tail of Capricorn. A 6, B 8, magnitude. Pos. 2430 34' Dis. 04".50 Epoch 1823.19 Striive. 242 08 04 .466 1847.70 Mitchel. These measures decide the character of the star. The components must be optically united. A FIXE GLOBULAR CLUSTER A. R. = 21 h. 25 m. 10 s. Dec. : 01 32' 01"; on the neck of Aquarius. Discovered by Meraldi in 1 746, more than a hundred years ago, and among the first known nebula. It was fully resolved by Sir William Herschel, with his 40 feet reflector, when the entire mass was found to consist of myriads of stars, ranged in a compressed form, and closely clustering about the center. He estimated its profundity as of the 243d order. This object CONSTELLATION OF AQUARIUS. 193 was examined with a power of 250, and a 12 inch aperture, on the evening of the 9th of September, 1845, and described as follows. The cluster enters the field in great beauty. It is distinctly resolved, though the stars composing it are very minute, with great condensation at and around the center. The diameter of the brightest portion is about 2' by estimation. A coarse double star follows above the cluster. Several bright stars in the field. There are no radiations of stars, the mass being nearly globular, with an outline somewhat broken. 41 AauARir A. R. = 22 h. 05 m. 27 s. Dec. = 21O 51' 00". A double star between the Water-bearer and the Southern Fish. A 6, B 8, magnitude. Discovered by Herschel, bul registered by him without measures. Pos. 1200 42' Dis. 05".17 Epoch 1823.78 Herschel & South. 120 22 04 .326 1847.70 Mitchel & L. An interval of 24 years between these measures, indicates the fixity of the components of these stars. AauARii.- A. R. = 22 h. 20 m. 35 s. Dec. = 00 50' 02". A binary star on the left wrist of Aquarius. A 4, B 4, magnitudes. Discovered by Herschel in 1779, and found to be binary as early as 1804. Pos. 3550 14' Dis. 03".525 Epoch 1830.98 Bessel. 352 43 03 .389 1836.05 Struve. 352 10 04 .123 1841.48 Miidler. 348 54 02 .70 1842.59 Smyth. 346 42 03 .948 1847.70 Mitchel. The last measures but one seem to be in error both in distance and position. Miidler thinks the period of this system may be about 780 years. My own measures were confirmed by those of my assistant, the readings agreeing admirably with each other. A CLOSE DOUBLE STAR. A. R. = 22 h. 34 m. 40 s. Dec. = 9 08' 08". near the stream issuing from the vase and near the vase's mouth. A 7, B 8, magnitude. Discovered by Herschel. Pos. 311 12' Dis. 03".00 Epoch 1782.74 Herschel. :<17 22 1821.92 Striive. 313' 08 02 .7 1838.67 Smyth. 314 35 01 .82 1847.70 Mitchel. The distance in this set seems to be diminishing, and a revolution in an orbit whose plane is nearly coincident with the visual ray appears probable. T AQ.UARIT. A. R. = 22 h. 39 m. 13 s. Dec. = 14 53' 09". Above the left knee of Aquarius. A 6, B 9, magnitude. Discovered by Herschel in 1782. A TRIPLE STAR. A. R. = 22 h. 39 m. 35 s. Dec. = &o 03* 05". In the mouth of the vase. A 7, B 8, C 9, magnitude, R 194 GEOGRAPHY OF THE HEAVENS. 94 AatTARii. A. R. = 23 h. 10 m.41 s. Dec. = HO 19' 07 . In the space between the stream and the left knee of Aquarius. A 6, B 8, magnitude. Discovered by Piazzi. 107 AQ.UAHII. A. R. = 23 h. 37 m. 42 s. Dec. = 19 34' 01". Near the center of the stream flowing from the urn. A 6, white; B 7^, blue. Discovered by Herschel in 1780. CAPRICORNUS. THE GOAT. This is the tenth sign, and eleventh constellation, in the order of the Zodiac, and is situated south of the Dolphin, and next east of Sagittarius. Its mean declination is 20 south, and its mean right ascension, 310. It is therefore on the meridian about the 18th of September. It is to be observed that the first point of the sign Capricorn, not the constellation, marks the southern tropic, or winter solstice. The sun, therefore, arrives at this point of its orbit the 21st of Decem- ber, but does not reach the constellation of Capricorn until the 16th of January. The sun having now attained its utmost declina- tion south, after remaining a few days apparently stationary, begins once more to retrace its progress northwardly, affording to the wintry latitudes of the north, a grateful presage of returning spring. At the period of the winter solstice, the sun is vertical to the tropic of Capricorn, and the south- ern hemisphere enjoys the same light and heat which the northern hemisphere enjoys on the 21st of June, when the sun is vertical to the tropic of Cancer. It is at this period, mid day at the south pole, and midnight at the north pole. The whole number of stars in this constellation is fifty one ; none of which are very conspicuous. The ,three largest are only of the 3d magnitude. There is an equal number of the 4th. CONSTELLATION OF CAPRICORNUS. The head of Capricorn may be recognized by means of two stars of the 3d magnitude, situated a little more than 2 apart, called Giedi, marked a, and Dabih, marked /3. They are 28 from the Dol- phin, in a southerly direction. Giedi is the most northern star of the two, and is double. If a line be drawn from Lyra through Altair, and produced about 23 farther, it will point out the head of Capricorn. These two stars come to the meridian the 9th of September, a few minutes after Sad'r, in Cygnus. A few other stars, of inferior note, may be traced out by reference to the maps. The sign of the Goat was called by the ancient orientalists the " Southern Gate of the Sun," as Cancer was denominated the " Northern gate." The ten stars in the sign Capricorn, known to the ancients by the name of the " Tower of Gad," are probably now in the constellation Aquarius. TELESCOPIC OBJECTS. at a CAPHICORISI. A. R. 20 h. 09 m. 10 s. Dec. = 13 02' 01". A double star of special interest. A 3, B 16, magnitude. This minute point of light was regarded by Sir John Herschel as possibly a satellite, and shining by a reflected light. On a cursory review of this region of the heavens, in September, 1846, I turned the instrument on a a Capricorn! in the presence of nearly a full moon, and instantly detected the small companion. I had forgotten that this was one of the stars to which Herschel had directed attention, and supposed that 1 might be the first who had seen the companion. A slight reference to the catalogues showed this to be wrong. It does not appear on Striive's great catalogue, neither do I find any measures, except a few of position by Sir John Herschel, in Sept. 26th r 1832. Pos. 141 42' No distance given. I measured this object in August and September, 1846, and found Pos. 1440 H' Dis. 6".36 This star is really quintupk, the most distant star of the five being 373" from the principal. t p CAPHICORNI. A. R. = 20 h. 19 m. 44 s. Dec. = 18 20' 02". A double star with a distant companion. A 5, B 9, C 7, mag. Pos. A B 1760 42' Dis. 3".8 Epoch 1830.73 Smyth. 176 56 3 .094 1847.70 Mitchel. This object is found on the right ear of Capricorn. 196 GEOGRAPHY OF THE HEAVENS. o 2 CAPHTCORNI. A. R. = 20 h. 20 m. 43 s. Dec. = 1QO 06' 04". A double star between the right ear and the eye of the aniiaaL A 6, B 7, magnitude. Pos. 239 09' Dis. 21 ".8 Epoch 1832.59 Smyth. The connexion is merely optical, as seems to be shown by the recorded measures. A GLOIIULAR CLUSTER. A. R. = 20 h. 44 m. 39 s. Dec. = 13 07' 06". Between Aquarius and the neck of Capricorn, due east of t Capricorni. Discovered by Messier in 1 780. , Resolved by Herschel, and pronounced to be in the 243d order of distances, and described by him as follows. " It is a cluster of stars of a round figure, but the very faint stars on the outside of globular clusters are generally a little dispersed, so as to deviate from a perfectly circular form There are many stars in the same field of view, but they are of several magnitudes, totally different from the excessively small ones which compose the cluster. It is not possible to form an idea of the number of stars which form such a cluster, but we are not to estimate them by hundreds." A FINE CLUSTER A. R. = 21 h. 31 m. 16 s. Dec. = 23 52' 04". Under the caudal fin of the animal. Discovered by Messier in 1764, who saw it circular, and without any star. Resolved by Sir William Herschel in 1783. Examined by myself in September, 1 847, and described as follows. An irregular cluster. It brightens at the center, and throws out three distinct radiations of stars. All are directed downwards, or towards the north. An 8th magnitude star precedes the cluster by about 5 minutes of arc. Several stars are in the field. In closing our review of the constellations, we present the following table, exhibiting, for each month in the year, the rising, culminating, and set- ting of the visible constellations. Rising. Hercules, Corona Borealis, Bootes, Virgo, Crater, Pyxis Nautica, Argo Navis. JANUARY. Cui/tiiriatittg. Draco, Polaris, Camelopardus, Lynx, Gemini, Monoceros, Canis Major. Setting. Cygnus, tfie neck, Pegasus, the hoofs, Pisces, the ribbon, Cetus, the body, Eridanus, Columba Noachi. TABLE OF CONSTELLATIONS. 197 FEBRUARY. Riaing. Culminating. Setting. Lyra, Cygnus, the tail, Pisces, the N. fish, Hercules, shoulders, Cepheus, the knee, Aries, the fore legs, Serpens, the head, Polaris, Cetus, the head, Virgo, the feet, Ursa Major, fore legs, Eridanus, Corvus, Lynx, the tail, Lepus, the fore legs, Hydra, the lower fold. Cancer, the claws, Canis Maj . , hind legs Hydra, the head. Argo Navis. MARCH. 4< Cygnus,foll'g wing Lyra, Lacerta, the back, Cepheus, the arm, Andromeda, the body, Triangulum, Hercules, the head, Polaris, Musca, Ophiuchus, the head, Ursa Major, hind legs Taurus, Serpens, the middle, Leo, thefiank, Orion, Libra, Crater, Canis Maj., the head. Hydra, the tail Hydra, the body. APRIL. Lacerta, Vulpecula, Andromeda, the body Cassiopeia, the waist Andromeda, the feet, Medusa's Head, Sagitta, Polaris, Taurus, the horns, Aquila, the tail, Ursa Major, the tail, Orion, the head, Ophiuchus, the knees, Canis Venatici, the Monoceros, fore legs, Scorpio, the head, Vergo, the waist, Pyxis Nautica, Centaurus, the head. Corvus, the tail. Antlia Pneumatica. MAY. Andromeda, the feet, Perseus, the head, Auriga, the tegs, Pega.sus, the fore kgs, Cassiopeia, the feet, Gemini, the legs, Equulus, the nose, Polaris, Cancer, Delphinus,^ body, Draco, the tail, Hydra, the heart, Antinous, Bootes, the body, Crater, Scorpio, the tail, Libra, Corvus, Lupus, ike head, /i Centaurus, the hand. Centaurus, the head. JUNE. Medusa's Head, Auriga, the kids, Gemini, the head, Triangulum, Camelopardus, Cancer, the body, Pisces, the N. fish, Polaris, Leo, the fore legs, Pegasus, the wing, Draco, the body, Sex. Uraniae, Aquarius, shoulders, Hercules, the back, dorvus, Capricornus, the head, Ophiuchus, Hydra, the tail, Sagittarius, the body. Scorpio, the tail. Lupus, the head. R2 198 GEOGRAPHY OF THE HEAVENS. JULY. Rising. Culminating. Setting Auriga, ttie waist., Lynx, the head, Lynx, the hind legs, Perseus, the feet, Camelopardus, neck, Leo Minor, the kgs t Musca, Polaris, Leo, the tail, Aries, the head, Draco, Virgo, the shoulders, Pisces, the tail, Lyra, Libra, Aquarius, the legs, Scutum Sobieski, Scorpio, the body. Sagittarius, the hips. Sagittarius, the head. / AUGUST. Lynx, the body, Ursa Maj., the head, Leo Minor, Gemini, Castor's arm Polaris, Coma Bernices, Auriga, the knees, Cepheus, the sceptre, Bootes, the feet, Taurus, the head, Cygnus, the body, Libra, Cetus, the mouth, Vulpecula, Serpentarius, leg** Pisces Australis, Delphinus, Sagittarius, the waist* Microscopium. Capricornus, neck. SEPTEMBER. Leo Minor, the head, Ursa Major, the body, Canes Venatici, Lynx, the hind legs, Draco, the tail, Bootes, the knees, Gemini, the bodies, Polaris, Serpens, the head, Orion, the shoulders, Cepheus, head <$- body Ophiuctfus, the waist, Eridanus, Pegasus, the chest, Scutum Sobieski, Cetus, the legs, Aquarius, Sagittarius, App. Sculptoris. Piscis Australis. Piscis Australis. OCTOBER. Leo Minor, the body, Ursa Major, the tail, Bootes, the shoulders, Cancer, the body, Draco, the tail, Corona Borealis, Canis Minor, head, Polaris, Hercules, shoulders, Monoceros, the neck, Cassiopeia, the head, Ophiuchus, the head, Orion, the kgj Andromeda, breast, Taurus Poniatowski, Lepus, the head, Pisces, the ribbon, Capricornus, the head Fornax Chemica. Cetus, the tati. Piscis Australis. NOVEMBER. Canes Venatici, Draco, the last coil, Hercules, the legs, Leo, the body, Ursa Minor, the head, Cerberus, et Ramus. Hydra, the head, Polaris, Sagitta, Monoceros, Perseus, shoulders, Aquila, the body, Canis Major, head, Aries, the body Equulusf Lepus, body, Cetus, the mouth, Aquarius, Eridanus. Fornax Chemica. App. Sculptoris. TABLE OF CONSTELLATIONS. DECEMBER. 199 Rising. Bootes, Coma Bernices, Leo, Sextans Uraniae, Hydra, Argo Navis, Canis Major. Culminating. Draco, the middle, Ursa Minor, haunch, Polaris, Camelopardus, body, Taurus, the head. Eridanus. Setting. Lyra, Cygnus, the head, Vulpecula, the legs, Pegasus, the head, Pisces, the W.Jish, Cetus, the tail, Fornax Chemica. N. B. The risings are taken along the horizon, from the north, round by the east, to the south ; the culminations from the north horizon, over the pole and zenith, and thence down to the south hori- zon ; the settings are reckoned from the north, by the west, round to the south. Polaris, though not always precisely on the meridian, is included in every month as a guide. THE FIXED STARS. 201 ; CHAPTER V. THE FIXED STARS THEIR DISTANCE AND MOTIONS THE MILKY WAY CLUSTERS NEBULJE. THUS far in our examination of the constellations, the stars have only been considered in their relations of apparent magni- tude or brilliancy and position. Their absolute magnitudes, distances, motions, and positions, have not been regarded, except as notices have been taken of a few among the telescopic objects. We propose to consider, now, the discoveries which have recently been made in sidereal astronomy ; and we commence with the parallax of the fixed stars. DEFINITION. The parallax of any heavenly body is the ap- parent change in its position, occasioned by any real change in the position of the spectator. Thus, if a person on the earth's surface should, while looking at the moon just rising, be suddenly transported down to the earth's center, as he descended the moon would appear to ascend, and this seeming change in the moon's place is a paralladic change. The rapid apparent whirling of the forest trees, occasioned by fly- ing swiftly past them in a coach or car, is a similar effect from a like cause. More accurately, the moon's parallax is the angle formed at the moon's center by two lines, the one drawn tangent to the earth's surface, the other drawn to the earth's center. In case a spectator could be transported to the moon's center, at the instant she is rising above the horizon of any place, and could see the earth's radius drawn to this place, the two visual rays drawn to the extremities of this radius would form an angle at the eye of the observer, which would be the moon's horizontal parallax. These two visual rays and the earth's radius form a triangle, in which one side (the earth's radius) is known, the angles are readily measured, and hence it becomes possible to learn the value of the remaining sides, either of which measures the moon's distance from the earth. When, therefore, the parallax of any heavenly body is once determined, it is an easy matter to compute its distance. If one could be transported to a fixed star, when rising, and view from this position the earth's radius, the angle formed by the visual rays drawn to the two extremities of this radius, would be the star's parallax. In consequence of the vast distance of the fixed stars, this angle, thus formed, is too minute to be appreciable ; no instruments devised by human skill or science, can be con- 202 GEOGRAPHY OF THE HEAVENS. structed so as to measure so minute a quantity. We are, there- fore, obliged to resort to some other method to determine the parallax of the stars. In case the earih were at rest in the universe, there would be no possibility of ever measuring the distance of the fixed stars; but its annual sweep around the sun in an orbit whose radius is about ninety-five millions of miles, transports the astronomer through space, around an orbit whose longest diameter is nearly two hundred millions of miles. If, now, the observer send up a visual ray to a fixed star, when at one extremity of the longest diameter of the earth's orbit, and at the end of six months, when he shall have reached the other extremity of the same diameter, he send up a second visual ray to the same star, these two rays will stand upon a base whose length is nearly two hundred millions of miles, and the angle formed by them, at the fixed star, will be its parallax. To render this plainer, suppose a globe bright as the sun, and of a diameter equal to that of the earth's orbit, filled this grand cir- cumference; the apparent diameter of such a globe, as seen from the star in' question, would be its parallax. At first view it would seem almost impossible to remove a spectator so far, that a globe of two hundred millions of miles in diameter should shrink to a point almost imperceptible, or that by distance its diameter should become scarcely perceptible with the most powerful instruments; yet this is literally true. To measure this apparent diameter, or to obtain the angle of the visual rays drawn from its extremities to a fixed star, has for more than a hundred years, called into requisition the highest skill, genius, and patience, ever put forth by man. The problem is no less than the determination of the distances of the fixed stars. Three pro- cesses have been employed in the investigation of this problem, each of which, and its results, we shall succinctly present. 1. BRADLEY'S METHOD. Suppose a telescope bolted firmly to a solid rock, hewn in the form of a vertical shaft. This rock is absolutely immovable, and the telescope is so situated that its axis is exactly vertical, and is perfectly immovable. In the focus of the eye piece of the telescope, let two spider's webs of the finest texture cross each other at right angles, and by their intersection form a point of almost mathematical minuteness, precisely in the axis of the telescope. With this instrument the astronomer is prepared to commence his research of the parallax of a fixed star. Placing his eye to the instrument, he watches until a certain fixed star enters the field of the telescope. It actually threads like a bead of light, the spider's line drawn parallel to the direction of the star's apparent diurnal motion ; it moves on, and the precise instant when it reaches the intersection of the spider's lines is noted and recorded, and thus the first observation is terminated. Now the telescope, its rocky base. THE FIXED STARS. 203 and the observer, are carried by the earth round the sun, and in case any change in the apparent place of the star is occasioned by the revolution of the earth in its orbit, as the star is watched night after night, throughout the year, it will be found slowly to leave the spider's line which it at first threaded, and gradu- ally to move either towards the north or south, while it fails to cross the center at the exact instant of time first recorded. A little thought will render clear this beautiful and simple method of ascertaining the parallax, or apparent change of place, of the fixed stars. Such was mainly the method employed by Bradley, the great English astronomer. Its accuracy was wonderful, but it failed to detect any parallax. Buried in depths almost infinite, the stars escaped from this first scrutinizing process. 2. HERSCHEL'S METHOD. In the outset of Herschel's explora- tions among the double stars, he believed them to be only optically related ; that is, their proximity was occasioned by the fact that the visual ray drawn by the observer to one star, passed almost exactly through the other. In case then, two stars could be found very near to each other, of whose compo- nents the one was about double the other, it was fair to conclude that the smaller was twice as remote as the larger, and jf properly chosen, the annual revolution of the earth in its orbit could hardly fail to cause some change in the relative positions of these stars. Suppose that on the first of January the small star is seen exactly on the right of the large one; at the end of three months it is seen a little to the south and just under the large one; at the close of six months it is to the left; at the end of nine months it is just above and a little north of the large star; and when the year closes it comes to resume its primitive position. In case such changes are repeated from year to year, and in the same order, and in many double stars, it is impossible to resist the conclusion that it is a parallactic change. Such was the method practised by Herschel, but an unforeseen discovery destroyed the hope of detecting the parallax in this way. It was found that these double stars, in many instances at least, were not merely related by accidental position, but were actually united by the great law of universal gravita- tion ; one star or sun revolving about the other, or rather the two suns revolving about their common center of gravity. The actual motions became, in this way, so involved in these only apparent or parallactic motions, that to distinguish them became impossible. These methods then failed to reveal the distances of the stars, although they were not without results of the most important character, and without a knowledge of which, the problem of the parallax could never have been resolved. Bradley discovered the nutation and aberration of the fixed stars, while Herschel reached the grand fact of the binary character of the double stars. 204 GEOGRAPHY OF THii HEAVENS. 3. BESSKL'S METHOD. After mounting a large telescope call- ed a hetiometer, peculiarly adapted for the micrornetrical measure of large as well as minute distances among the double stars, Bessel selected 61 Cygni as the object on which he determined to concentrate his entire attention. This double star was eligi- bly situated in the heavens, and could be observed nearly every mo.nth in the year. It had near it several minute stars which could be used as points of reference, and finally the rapidity of its proper motion indicated its probable nearness to our sun and system. Bessel selected two minute stars as points of reference, the one in a line nearly perpendicular to the middle point of the line joining the components of 61 Cygni, the other in the direc- tion of this line. With the heliometer he measured the distance of the middle point of the line joining the components of 61 Cygni, from each of the points of reference, 16 times each night, and finally detected a change in these distances which seemed to depend on the orbitual revolution of the earth. Some three years of observation confirmed the accuracy of the first results, and gave the parallax of this double star equal to 0".3480, or only about three-tenths of one second of arc, so that if a globe of 100,000,000 of miles in diameter, could be seen from this fixed star, its diameter would not appear greater than about the six- thousandth part of the sun's apparent diameter. The parallax once obtained, the distance is readily deduced, and is found to be 657,700 times greater than the earth's distance from the sun, or so remote that the light of the star only reaches us after a jour- ney of more than ten years, although it flies at the rate of twelve millions of miles in every minute. The distance of the double star being known, observation gives us about 540 years for the period in which the components revolve around their common center of gravity in an orbit whose diameter is about ninety times the diameter of the earth's orbit, while the amount of matter in these two stars is a little less than half that contained in our sun. Since Bessel determined the parallax of 61 Cygni, other astronomers have pursued the investigation with success. The following have been deduced by the Russian astronomer M. Peters, and announded in a recent work by M. Striive, of Pulkova. Absolute parallax of 61 Cygni + 00".349. " " * Lyra? -f 00 .103. , " Polaris -f 00 .067. " " Groombridge No. 1830 -f- 00 .226. " " * Aurigae or Copella -|- 00 .046, Ursa Major -f- 00 .133. a. Botitis, Arcturis -4- 00 .127. THK FIXED STARS. 205 From the table it is readily seen that 61 Cygni is the nearest of all the fixed stars whose distances have been discovered. M. Striive, by a beautiful train of reasoning, deduces the rela- tive distances of the stars of the various magnitudes, from the 1st to the 6th magnitude inclusive, and finds them to constitute a geometrical progression whose common ratio is 1 divided by the square root of 2. Calling the distance of the 6th magni- tude stars 10 000 he finds Magnitude. Dist. determined. 6 1.0000 1 0000. 5 0.6998 0.7071. 4 0.5001 0.5000. 3 0.3602 0.3536. 2 0.2413 0.2500. 1 0.1424 0.1768. It will be seen that the numbers in the two columns scarcely differ, except in the case of stars of the 1st magnitude, and here too few exist to furnish M. Striive with the requisite data for his computations. So that this most curious law of distances would seem to be founded in nature. Every even term is half the preceding even one, and the same of every odd term. If it were now possible to determine the absolute mean distance of the stars of any one magnitude, the real distances of all other magnitudes would readily be derived from this remarkable law. This has been approximately accomplished by the Russian astronomers. From the actual parallax of about thirty stars of the 2d magnitude, the value of the mean parallax of all the stars of that magnitude has been derivecT, and we are now able to present the following table: App. mag. 1 Distance (radius of ) ( Time for light to Parallax. /Earth's orbit =1). S I'^um* jit wirs 1 00' '.166 1,216.000 19.6 2 00 .098 2,111.000 33.3 3 00 .065 3,151.000 49.7 4 00 .047 4,375.000 69.0 5 00 .034 6,121.000 96.6 6 00 .024 8,746.000 137.9 7 00 .014 14,230.000 224.5 8 00 .008 24,490.000 386.3 9 00 .006 37,200.000 5865 Herschel's smallest stars Joo .00092 224,500.000 3541.0 It is not pretended that these results are absolute. These values are only approximate, but the errors are comparatively small; and show to us clearly, the vastness of the universe of God. S 206 GEOGRAPHY OF THE HEAVENS. Having learned in this way the distances cf the fixed stars, the inquiry arises, how are these objects distributed throughout space? Are they scattered indifferently in all directions, and at distances nearly equal from each other, or is their distribution governed by any attainable law? The bright circle of light called the Milky Way^ which sweeps round the entire circuit of the heavens, and which to the naked eye appears only faintly luminous, when examined with the telescope, is found to consist of millions of stars, crowded and condensed together with the most extraordinary richness and profusion. Herschel conceived the idea of measuring the depths to which the stars extended in the Milky Way, and by reaching out beyond its extreme limits, ascertaining the figure which would be formed by cutting this vast bed of stars by a plane drawn perpendicularly to its surface. It is manifest, that if the stars are all at equal distances, and finite in number, that wherever the stratum extends deepest into space, there will we be enabled to count the greatest number of stars in the field of a given telescope. And indeed, the number counted in any two directions, by the same telescope, will give the relative depth to which the stars extend at these two points. Such was Herschel's plan of sounding the Milky Way, and of learning its figure. With the full power of his twenty feet reflecting telescope, he thought it possible to pierce through even the deepest portions of the Milky Way, and to send the visual ray far beyond. This idea, so long maintained by the followers of Herschel, has recently been attacked by Prof. Striive of Pulkova, who maintains that it was abandoned by Herschel himself in his later papers. Sir John Herschel does not accord with the views of Striive, but maintains the original opinions of his father. From the investigations of the two Herschels, the vast stra- tum of stars, called the Milky Way, appears to be arranged under the figure of a flat ring, whose thickness is small when compared with its diameter. The central parts of the ring are not so thickly strewn with stars as the outer portions or circum- ference. The rim is divided into two branches, or streams of stars, which diverge from each other for a certain distance, but finally re-unite and flow on together. The two Herschels have made a sufficient number of observations to determine the figure cut from this bed of stars by a plane perpendicular to its surface, and cutting across the portion where the two streams are most distant from each other. There are portions of the Milky Way included in this section, in which it is said, the stars extend so deep in space that the series in a right line, from the sun out to the extreme limit, cannot number less than five hundred stars, each as remote from the other as 61 Cygni is from our sun. ID case we admit this statement, there are stars belonging to oui THE MILKY WAY. 207 Milky Way so widely separated, that their light will require more than ten thousand years to pass from one to the other, or to sweep across the longest diameter of this mighty universe of stars. If Striive's idea of the absolute unfathomable character of the Milky Way be adopted, it only increases the sweep or range of suns and systems, grouping them into subordinate clusterings, and uniting them into one unbounded, immeasurable, ^numer- able, whole. In whatever way, under whatever aspect, we contemplate this vast constellation of constellations ; this mag- nificent cluster of clusters ; the number, distance, magnitude, and brilliancy, of its components, cannot fail to fill the mind with wonder and astonishment. Admitting that the telescopic vision sweeps beyond the limits of the Milky Way, it may be asked, what does the eye encounter in these remote regions ? Many objects lying in these far distant portions of space, have already been noticed among the tele- scopic objects of the different constellations. These are the clusters and nebulas. By a careful examination of these wonder- ful objects, Herschel finally reached the conclusion, that all the clusters^ and many of the nebulae, were immense aggregations of stars, forming separate universes, as extensive and rich as the Milky Way itself. He even ventured to attempt the measure of the relative depths of these remote objects. His method is simple, and may be readily comprehended. The naked eye can discern stars of the sixth magnitude, or those twelve times as remote as Sirius, the largest and brightest star in the heavens. In case the pupil of the eye could be expanded to twice its present dimensions, it could then penetrate twice as deep into space as it now can, or would see Sirius if it were removed backward twenty-four times deeper into space. Now, although the pupil of the eye cannot literally be expanded to twice or thrice its present size, the telescope comes in to accomplish precisely the same effects ; and admitting that an object glass permits all the light which falls on it to pass through, its power to penetrate space will be in the ratio of its surface to that of the pupil of the human eye. By covering a large object glass with circular coverings, pierced with apertures of one inch, two inches, &c., diameter in the center, we may give to it, at pleasure, different space penetra- ting powers. Fixing the relation of these to the eye, we are pre- pared to examine any object, and determine, approximately, its distance. Suppose a nebula is seen faintly visible, with three inches of aperture to the object glass. We expand the aper- ture to four inches it appears brighter, but no 'stars are seen. We increase the aperture to five inches, the nebula grows still brighter at the center, but as yet no point-like stars are visible ; a farther increase to six inches, however, shows the object to 208 GEOGRAPHY OF THE HEAVENS. consist of millions of minute stars, just rendered visible to the eye. Now the length of the visual ray of the telescope, com- pared with that of the unaided eye, is readily determined; and knowing this, we learn, approximately, the distance of this cluster of stars. In this way Sir W. Herschel determined the profundity of all the principal clusters. Some of the nebulae could not, by any space penetrating power of his great telescopes, be resolved into stars. Their shapes were irregular, and their outlines ill defined. Some were easily visible to the naked eye, and yet no telescopic power could resolve them into stars. Others were found to contain occasional stars, with centers of more or less condensed light ; finally, stars were found surrounded by a nebulous haze of vast extent, whose center was occupied by the star. Examining and comparing all these phenomena, Herschel finally reached the conclusion, that while vast numbers of apparent nebulae were real clusters of stars, yet there were some in which the material composing them was a kind of luminous mist, like that forming the tails of comets. He conjectured that this chaotic matter might possibly furnish the material out of which, by condensa- tion, stars might be forming. The nebulous stars, as well as the planetary nebula, seemed to accord very perfectly with this hypothesis. Double and triple nebulae were found, from which the double and triple stars might eventually spring, and thus grew up, imperceptibly, the outlines of a magnificent theory, a sort of sublime cosmogony of the universe. These speculations, enlarged by La Place, as we shall see hereafter, were made to render an account of the sun and planets, and the peculiar arrangement of the solar system. The nebular theory, as it is termed, had for a long while its ardent supporters, and if not absolutely adopted by distinguished astronomers, at least, it was received by them with no inconsiderable favor. The resolution of the nebula in Orion, by Lord Rosse, and by Prof. Bond, of Cambridge, has in some degree shaken the faith of some in this remarkable hypothesis, while it is justly remarked, that Herschel only adopted it after the resolution of hundreds of nebulae. In case we abandon the idea of chaotic matter existing in space, and adopt the notion that the filmy, almost spiritual, objects, which barely stain with light the blue of the heavens, are immense congeries of stars, it only expands our knowledge of the illimitable extent of the universe of God. Some of these objects are so remote, that a hundred thousand years must roll away, before the light which they emit could traverse the dis- tance by which we are separated from them. Many of the clusters of stars appear under globular forms, and from the manifest condensation about their centers, seem to in- dicate the existence of some active energetic power, like gravita- THE MILKY WAY. 209 tion, which is exerting its influence on the individual stars of these grand systems. The extension of the law of universal gravitation to the region of the fixed stars, was long believed, before it could be positively demonstrated. By the discovery of the binary or revolving suns, this conjecture became a positive fact. In a large number of instances, the orbits described by these bodies around their common centers of gravity, have been com- puted according to the law of gravitation, and in every instance the predictions have been verified. That stars do attract each other is now positively demonstrated, and the law of attraction is the inverse ratio of the square of the distance, or that of gravita- tion. If two or three stars, grouped together, are subject to this law, it is reasonable to conclude that larger collections, such as the Pleiades, or Coma Berenices, may be under the controlling power of the same force. And if this be true, why not extend its operation to the mighty cluster of clusters, the Milky Way itself. This has been done recently by M. Madler, of Dorpat, Russia, and he thi-nks he has determined, approximately, the center of the stratum of stars, or the astral system, composing the Milky Way. By comparing the absolute places of the fixed stars, at intervals of one or two hundred years, it is found that a large number of them are in motion, and with an appreciable velocity. This is not merely apparent, but in many instances must be absolute change of place in space. Some stars are moving very swiftly, and exhibit their progressive changes in a few months ; while others, again, move with such extreme slowness, that even hundreds of years are necessary to render their change appre- ciable. It seems quite as reasonable to suppose that these com- plex and involved motions of the distant stars, should be governed by some simple and beautiful law, as that the planets, whose apparent motions were far more complicated, should be reduced to order and simplicity. This great task of unraveling the complicated phenomena of the proper motion of the fixed stars, has been attempted by the Russian astronomer. It had long been conjectured that the analogy existing in the solar system would hold among the systems of stars. And that as the sun was vastly larger than his revolving planets, and as each primary planet was much superior to his revolving moons, so there might exist in space some mighty central sun, whose vast proportions would far exceed all the stars subject to its con- trolling influence. This analogy was broken by the discovery of the binary stars. Here we find many instances in which the components are exactly equal in magnitude ; others, again in which the one is slightly superior to the other ; in short, all possi- ble relations of magnitude. This does not interfere with the sta- bility and perfection of the systems. The components revolve about their common center of gravity as though it were filled s2 210 GEOGRAPHY OF THE HEAVENS. with a mass of solid matter. Madler rejects the idea, then, of the existence of any vast central globe, and argues thut in case it existed, it would be impossible to prevent its discovery. The stars in its immediate neighborhood would reveal it by their swift- er proper motions ; as no such motions are known, or have ever been discovered, it is fair to conclude that none such exist, and that there is no central predominant orb, but a mere center of gravity, which should be the object of research. By a train of beautiful and ingenious reasoning, he demonstrates to his own satisfaction, that this central point must be found somewhere in the Milky Way, and finally locates it in the cluster called the Pleiades, The brightest star of the group is called Alcyone or Tauri, and the star at present occupies the center of gravity of the. grand stratum of stars composing the Milky Way^ and around this center all the millions of stars are slowly performing their vast revolutions. Among these our own sun and system is comprehended, and Madler estimates that one single revolution of the sun around this distant center requires no less than eighteen millions two hun- dred thousand years. The distance of Alcyone from our sun cannot be less than thirty-four millions of times the radius of the earth's orbit. Should the universe endure so long, at the end of nine or ten millions of years, the revolution of the sun in its orbit will cause a total change in the apparent relative positions of the fixed stars. The present well known constellations will have been swept from the heavens, and new configurations of the stars will have usurped the places of the old ones. No new creation will cause these changes, but they come as the in- evitable consequences of the motion of the solar system. When we shall have examined the construction of this system, we shall then present the evidences of its swift translation through space. It seems next to impossible to estimate the number of fixed stars constituting our own astral system. Catalogues of all the brighter stars have been formed. Some of these contain even fifty thousand stars, observed by a single individual. Striive reaches the conclusion, that Herschel's twenty feet reflector could reach no less than twenty millions three hundred and seventy-four thousand stars in the celestial sphere ; and it has been estimated that the forty feet instrument would carry the number up to at least one hundred millions. Let it be remembered that these stars compose but a single astral system, or as the Germans term them " Island Universes." More than three thousand of these systems have been discovered, some of them doubtless far more magnificent and populous in stars than our own ; and yet all these innumerable worlds and suns and systems have been brought within the range of human vision by the powers of the telescope. THE MILKY WAY. 21 The power of this instrument in penetrating space is only equaled by its extraordinary capacity to divide space. The micrometer of the great refractors now in use, can divide a single inch into eighty thousand equal parts ! and should two close fixed stars commence to separate from each other hy so small a quan- tity that even three millions of years would be required for a complete revolution in the heavens, these delicate instruments would detect the motion in a single year. With such instru- ments, it is not wonderful that human genius dares the most dif- ficult researches. 212 GEOGRAPHY OF THE HEAVENS. CHAPTER VI. GENERAL PHENOMENA OF THE SOLAR SYSTEM. THUS far our attention has been directed to the phenomena of the sidereal heavens. The names, positions, and relative mag- nitudes of the stars; their changes of light, proper motion, and physical association into systems of greater or less complexity, have been considered and explained. The mind has penetrated but a comparatively short distance in its investigations of the starry heavens, and a great many mysterious points yet remain to be explained. The phenomena of the new stars, of the lost stars, of the nebulous stars, of the variable stars, all remain without satisfactory explanation. Advances are constantly making; and reasoning from past success, the future may be looked forward to with the highest anticipations. The confir- mation or disproof of the nebular theory, and of Miiedler's hypothesis of the central sun, will probably in a few years reward the diligent and unremitting researches of philosophers. Leaving the region of the fixed stars, there now remain to be considered certain other celestial bodies, all of which, from their remarkable appearance and changes, and some of them from their intimate connection with the comfort, convenience, and even existence of man, must have always attracted especial observation, and been objects of the most intense contemplation and the deepest interest. Most of these bodies are situated within the limits of the Zodiac. The most important of them are, the Sun, so superior to all the heavenly bodies for its apparent magnitude, for the light and heat which it imparts, for the marked effects of its changes of position in regard to the Earth ; and the Moon, so conspicuous among the bodies which give light by night, and from her soft and silvery brightness, so pleasing to behold; remarkable not only for changes of position, but for the varied phases or appearances which she presents, as she waxes from her crescent form through all her different stages of increase to a full orb, and wanes back again to her former distinguished figure. The partial or total obscuration of these two bodies, which sometimes occurs, darkness taking place even at mid-day, and the face of night, before lighted up by the moon's beams, being suddenly shaded by their absence, have always been among THE SOLAR SYSTElvlT. 213 the most striking astronomical phenomena; and so powerful in their influence upon the beholders, as to fill them with perplexity and fear. If we observe these two bodies, we shall find, that, besides their apparent diurnal motion across the heavens, they exhibit other phenomena, which must be the effect of motion. The sun, during one part of the year, will be seen to rise every day further and further toward the north, to continue longer and longer above the horizon, to be more and more elevated at mid- day, until he arrives at a certain limit; and then, during the other part, the order is entirely reversed. The moon sometimes is not seen at all; and then, when she first becomes visible, appears in the west, not far from the setting sun, with a slender crescent form. Every night she appears at a greater distance from the setting sun, increasing in size, until at length she is found in the east, just as the sun is sinking below the horizon in the west. The sun, if his motions be attentively observed, will be found to have another motion, opposite to his apparent diurnal motion from east to west. This may be perceived distinctly, if we no- tice, on any clear evening, any bright star, which is first visible after sunset, near the place where he sunk below the horizon. The following evening, the star will not be visible on account of the approach of the sun, and all the stars on the east of it will be successively eclipsed by his rays, until he shall have made a complete apparent revolution in the heavens. These are the most obvious phenomena exhibited by these two bodies. There are, also, situated within the limits of the zodiac, cer- tain other bodies, which, at first view, and on a superficial exa- mination, are scarcely distinguishable from the fixed stars. But observed more attentively, they will be seen to shine with a milder and steadier light; and besides being carried round with the stars, in the apparent revolution of the great celestial concave, they will seem to change their places in the concave itself. Sometimes they are stationary ; sometimes they appear to be moving from west to east, and sometimes to be going back again from east to west ; being seen at sunset sometimes in the east, and sometimes in the west, and always apparently chang- ing their position with regard to the earth, each other, and the other heavenly bodies. From their wandering, as it were, in this manner, through the heavens, they were called by the Greeks r\tvT3Li, planets, which signifies wanderers. There also sometimes appear in the heavens bodies of a very extraordinary aspect, which continue visible for a considerable pe- riod, and then disappear from our view ; and nothing more is seen of them, it may be for years, when they again present themselves, and take their place among the bodies of the celestial sphere. They are distinguished from the planets by a dull and cloudy 214 GEOGRAPHY OF THE HEAVENS. appearance, and by a train of light. As they approach the sun, however, their faint and nebulous light becomes more and more brilliant, and their train increases in length, until they arrive at their nearest point of approximation, when they shine with their greatest brilliancy. As they recede from the sun, they gradually lose their splendor, resume their faint and nebulous appearance, and their train diminishes, until they entirely disappear. They have no well defined figure ; they seem to move in every possible direction, and are found in every part of the heavens. From their train, they were called by the Greeks K^*/, comets, which signifies having long hair. The causes of these various phenomena must have early con- stituted a very natural subject of inquiry. Accordingly, we shall find, if we examine the history of the science, that in very early times there were many speculations upon this subject, and that different theories were adopted to account for these celestial appearances. The Egyptians, Chaldeans, Indians, and Chinese, early possessed many astronomical facts, many observations of important phenomena, and many rules and methods of astronomical calculation ; and it has been imagined, that they had the ruins of a great system of astronomical science, which, in the earliest ages of the world, had been carried to a great degree of perfection, and that, while the principles and explanations of the phenomena were lost, the isolated, unconnected facts, rules of cal- culation, and phenomena themselves, remained. Thus, the Chinese, who, it is generally agreed, possess the oldest authentic observations on record, have recorded in their annals a conjunction of five planets at the same time, which happened 2461 years before Christ, or 100 years be- fore the flood. By mathematical calculation, it is ascertained that this conjunction really occurred at that time. The first observation of a solar eclipse, of which the world has any knowledge, was made by the Chi- nese, 2128 years before Christ, or 220 years after the deluge. It seems, also, that the Chinese understood the method of calculating eclipses ; for, it is said that the emperor was so irritated against the great officers of state for neglecting to predict the eclipse, that he caused them to be put to death.* The astronomical epoch of the Chinese, according to Bailly, commenced with Fohi, -their first emperor, who flourished 2952 years before the Christian era, or about 350 years before the deluge. If it be asked how the knowledge of this antediluvian astronomy was preserved and transmitted, it is said that the columns on which it was registered have survived the deluge, and that those of Egypt^are only copies, which have become originals, now that the others have been for- gotten. The Indians, also, profess to have many celestial observations of a very early date. The Chaldeans have been justly celebrated in all ages for their astronomical observations. When Alexander took Baby- * It is well known that the Chinese have, from time immemorial, considered their solar eclipses and conjunctions of the planets ns prognostics of importance to the empire, and that they have been predicted us a matter of state policy. THE SOLAR SYSTEM. 215 ton. his preceptor, Callistlienes, found a series of Chaldean observations, made in that city, and extending back, with little interruption, through a period of 1903 years preceding that event. This would carry us back to at least 2234 years before the birth of Christ, or to about the time of the dispersion of mankind by the confusion of tongues. Though it he conceded that, upon this whole period in the history of the science, the obscurity of very remote antiquity must necessarily rest, still it will remain evident that the phenomena of the heavenly bodies had been observed with great attention, and had been a subject of no ordinary interest. But, however numerous or important were the observations of oriental antiquity, they were never reduced to the shape and symmetry of a regu- lar system. The Greeks, in all probability, derived many notions in regard to this science, and many facts and observations, from Egypt, the great fountain of ancient learning and wisdom, and many were the speculations and hypotheses of their philosophers. In the fabulous period of Grecian history, Atlas, Hercules, Linus and Orpheus, are mentioned as persons distinguished for their knowledge of astronomy, and for the improvements which they made in the science. But, in regard to this period, little is known with certainty, arid it must be considered, as it is termed, fabulous. The first of the Greek philosophers who taught astronomy, was Thales, of Miletus. He flourished about 640 years before the Christian era. Then followed Anaximander, Anaximenes, Anaxagoras, Pythagoras, Plato. Some of the doctrines main- tained by these philosophers were that the earth was round ; that it had two motions, a diurnal motion on its axis, and an an- nual motion around the sun ; that the sun was a globe of fire ; that the moon received her light from the sun ; that she was habitable, contained mountains, seas, &c.; that her eclipses were caused by the earth's shadow ; that the planets were not de- signed merely to adorn our heavens; that they were worlds of themselves; and that the fixed stars were centers of distant systems. Some of them, however, maintained that the earth was flat; and others, that, though round, it was at rest in the center of the universe. When that distinguished school of philosophy was established at Alexandria, in Egypt, by the munificence of the sovereigns to whom that portion of Alexander's empire had fallen, astronomy received a new impulse. It was now, in the second century after Christ, that the first complete system or treatise of astro- nomy, of which we have any knowledge, was formed. All be- fore had been unconnected and incomplete. Ptolemy, with the opinions of all antiquity, and of all the philosophers who had preceded him, spread out before him, composed a work, in thir- teen books, called the M^etxw Ewr*%ts> or Great System. Re- jecting the doctrine of Pythagoras, who taught that the sun was the center of the universe, and that the earth had a diurnal mo 216 GEOGRAPHY OF THE HEAVENS. tion on its axis and an annual motion around the sun, as contrary to the evidence of the senses, Ptolemy endeavored to account for the celestial phenomena, by supposing the earth to be the center of the universe, and all the heavenly bodies to revolve around it. He seems to have entertained an idea, in regard to the supposi- tion that the earth revolved on its axis, similar to one which some entertain even at the present day. " If," says he, " there were any motion of the earth, common to it and all other heav- enly bodies, it would certainly precede them all, by the excess of its mass being so great; and animals, and a certain portion of heavy bodies, would be left behind, riding upon the air, and the earth itself would very soon be completely carried out of the heavens." In explaining the celestial phenomena, however, upon his hypothesis, he met with a difficulty in the apparently stationary attitude and retro- grade motions which he saw the planets sometimes have. To explain this, however, he supposed the planets to revolve in small circles, which he called epicycles, which were, at the same time, carried around the earth in larger circles, which he called diiferents, or carrying circles. In following out his theory, and applying it to the explanation of different phenomena, it became necessary to add new epicycles, and to have re- course to other expedients, until the system became unwieldy, cumbrous, and complicated. This theory, although astronomical observations con- tinued to be made, and some distinguished astronomers appeared from time to time, was the prevailing theory until the middle of the fifteenth century. It was not, however, always received with implicit confidence ; nor were its difficulties always entirely unappreciated. Alphonso X, king of Castile, who flourished in the thirteenth century, when contemplating the doctrine of the epicycles, exclaimed, " were the universe thus constructed, if the Deity had called me to his counsels at the creation of the world, I could have given him good advice." He did not, however, mean any impiety or irreverence, except what was directed against the system of Ptolemy. About the middle of the fifteenth century, Copernicus, a native of Thorn, in Prussia, conceiving a passionate attachment to the study of astronomy, quitted the profession of medicine, and de- voted himself, with the most intense ardor, to the study of this science. " His mind," it is said, " had long been imbued with the idea that simplicity and harmony should characterize the ar- rangements of the planetary system. In the complication and disorder which, he saw, reigned in the hypothesis of Ptolemy, he perceived insuperable objections to its being considered as a representation of nature." In the opinions of the Egyptian sages, in those of Pythagoras, Philolaus, Aristarchus and Nicetas, he recognised his own ear- liest conviction that the earth was not the center of the universe. His attention was much occupied with the speculation of Mar- THE SOLAR SYSTEM. 217 tinus Capella, who placed the sun between Mars and the moon, and made Mercury and Venus revolve around him as a center ; and with the system of Appollonius Pergceus, who made all the planets revolve around the sun, while the sun and moon were carried around the earth, in the center of the universe. The examination, however, of these hypotheses gradually ex- pelled the difficulties with which the subject was beset, and, after the labor of more than thirty years, he was permitted to see the true system of the universe. The sun he considered as im- movable, in the center of the system, while the earth revolved around him, between the orbits of Venus and Mars, and pro- duced, by its rotation about its axis all the diurnal phenomena of the celestial sphere. The other planets he considered as re- volving about the sun, in orbits exterior to that of the earth. Thus the stations and retrogradations of the planets were the necessary consequence of their own motions, combined with that of the earth about the sun. He said that, " by long observation, he discovered, that, if the motions of the planets be compared with that of the earth, and be estimated according to the times in which they perform their revolutions, not only their several appearances would follow from this hypothesis, but that it would so connect the order of the planets, their orbits, magni- tudes, and distances, and even the apparent motion of the fixed stars, that it would be impossible to remove one of these bodies out of its place without disordering the rest, and even the whole of the universe also." Soon after the death of Copernicus, arose Tycho Brahe, born at Knudstorp, in Norway, in 1546. Such was the distinction which he had attained as an astronomer, that, when dissatisfied with his residence in Denmark, he had resolved to remove, the king of Denmark, learning his intentions, detained him in the kingdom, by presenting him with the canonry of Rothschild, with an income of 2000 crowns per annum. He added to this sum a pension of 1000 crowns, gave him the island of Huen, and established for him an observatory, at an expense of about 200.000 crowns. Here Tycho continued, for twenty-one years, to enrich astronomy with his observations. His "observations upon the moon were important, and upon the planets, numerous and precise, and have formed the data of the present generaliza- tions in astronomy. He, however, rejected the system of Coper- nicus ; considering the earth as immovable, in the center of the system ; while the sun, with all the planets and comets revolving around him, performed his revolution around the earth; and, in the course of twenty-four hours, the stars also revolved about the central body. This theory was not as simple as that of Coper- nicus, and involved the absurdity of making the sun, planets, &c., revolve around a body comparatively insignificant. T 218 GEOGRAPHY OF THE HEAVENS. Near the close of the 15th century, arose two men, who wrought most important changes in the science, Kepler and Galileo ; the former a German, the latter an Italian. Previous to Kepler, all investigations proceeded upon the sup- position that the planets moved in circular orbits, which had been a source of much error. This supposition Kepler showed to be false. He discovered that their orbits were ellipses. The orbits of their secondaries, or moons, he also found to be the same curve. He next determined the dimensions of the orbits of the planets, and found to what their velocities in their motions through their orbits, and the times of their revolutions, were proportioned ; all truths of the greatest importance to the science. While Kepler was making these discoveries of facts, very essential for the explanation of many phenomena, Galileo was discovering wonders in the heavens never before seen by the eye of man. Having improved the telescope, and applied it to the heavens, he observed mountains and valleys upon the surface of our moon; satellites or secondaries were discovered revolving about Jupiter ; and Venus, as Copernicus had predicted, was seen exhibiting all the different phases of the moon, waxing and waning as she does, through various forms. Many minute stars, not visible to the naked eye, were descried in the Milky Way ; and the largest fixed stars, instead of being magnified, appeared to be small brilliant points, an incontrovertible argument in favor of their immense distance from us. All his discoveries served to confirm the Copernican theory, and to show the ab- surdity of the hypothesis of Ptolemy. Although the general arrangement and motions of the planetary bodies, together with the figure of their orbits, had been thus determined, the force or power which carries them around in their orbits, was as yet unknown. The discovery of this was reserved for the illustrious Newton.* By reflecting on the nature of gravity that power which causes bodies to descend towards the center of the earth since it does not sensibly diminish at the greatest distance from the center of the earth to which we can attain, being as powerful on the loftiest mountains as it is in the deepest caverns he was led to imagine that it might extend to the moon, and that it might be the power which kept her in her orbit, and caused her to revolve around the earth. He was next led to suppose that perhaps the same power carried the primary planets around the sun. By a series of calculations, he was enabled at length to establish the fact, that the same force which determines the fall of an apple to the earth, carries the moons in their orbits around the sun. * The discovery of Newton was in some measure anticipated by Copernicus, Kepler and Hooke. THE SOLAR SYSTEM. 219 To recapitulate briefly : the system (not hypothesis, for much of it has been established by mathematical demonstration), by which we are now enabled to explain with a beautiful simplicity the different phenomena of the sun, planets, moons, and comets, is, that the sun is the central body in the system ; that the planets and comets move round him in elliptical orbits, whose planes are more or less inclined to each other, with velocities bearing 1 to each other* a certain ascertained relation, and in times related to their distances ; that the moons, or secondaries, revolve in like manner, about their primaries, and at the same time accompany them in their motion around the sun : all meanwhile revolving on axes of their own ; and that these revo- lutions in their orbits, are produced by the mysterious power of attraction. The particular mode in which this system is ap- plied to the explanation of the different phenomena, will be ex- hibited as we proceed to consider, one by one, the several bodies above mentioned. ( These bodies, thus arranged and thus revolving, constitute what is termed the solar system. The planets have been divided into two classes, primaries and secondaries. The latter are also termed moons, and sometimes satellites. The secondaries are those which resolve about the primaries. There have been dis- covered sixteen primaries ; namely, Mercury, Venus, the Earth, Mars, Vesta, Juno, Ceres, Pallas, Astrea, Hebe, Iris, Flora, Melis, Jupiter, Saturn, Urauns, Neptune. Mercury is the planet nearest to the sun, then follow the others in the order in which they are named. The nine small planets between Mars and Jupiter are telescopic, and have been termed asteroids. There have been discovered nineteen secondaries, or moons. Of these, the Earth has one, Jupiter four, Saturn seven, Uranus six, and Neptune one. None of these, except our moon, are visible without telescopic aid. We proceed to examine the objects constituting the solar system, in detail. * The orbits or paths of the planets wore oiscovered by tracing the course of the planet by means of the fixed stars 220 GEOGRAPHY OF THE HEAVENS. CHAPTER VII. THE SUN. THE sun is a vast globe, in the center of the solar system, dispensing light and heat to all the planets, and governing all their motions. It is the great parent of vegetable life, giving warmth to the seasons, and color to the landscape. Jts rays are the cause of various vicissitudes on the surface of the earth and in the at- mosphere. By their agency, all winds are produced, and the waters of the sea are made to circulate in vapor through the air, and irrigate the land, producing springs and rivers. The sun is by far the largest of the heavenly bodies whose dimensions have been ascertained. Its diameter is something more than 883,000 miles. Consequently, it contains a volume of matter equal to fourteen hundred thousand globes of the size of the earth. Of a body so vast in its dimensions, the human mind, with all its efforts, can form no adequate conception. The whole distance between the earth and the moon would not suffice to embrace one-third of its diameter. Were the sun a hollow sphere, perforated with a thousand openings to admit the twinkling of the luminous atmosphere around it and were a globe as large as the earth placed at its center, with a satellite as large as our moon, and at the same distance from it as she is from the earth, there would be present to the eye of a spectator on the interior globe, a universe as splendid as that which now appears to the uninstructed eye a universe as large and extensive as the whole creation was con- ceived to be, in the infancy of astronomy. The next thing which fills the mind with wonder, is the dis- tance at which so great a body must be placed, to occupy, ap- parently, so small a place in the firmament. The sun's mean distance from the earth is twelve thousand times the earth's diameter, or a little more than ninety-five millions of miles. We may derive some faint conception of such a distance, by considering that the swiftest steamboats, which ply our waters at the rate of two hundred miles a day, would not traverse it in thirteen hundred years , and, that a cannon ball, flying night and day, at the rate of sixteen miles a minute, would not reach it in eleven years. THE SUN. 221 The sun, when viewed through a telescope, presents the ap- pearance of an enormous globe of fire, frequently in a state of violent agitation or ebullition ; dark spots of irregular form, rarely visible to the naked eye, sometimes pass over his disk, from east to west, in the period of nearly fourteen days. These spots are usually surrounded by a penumbra, and that, by a margin of light, more brilliant than that of the sun. A spot when first seen on the eastern edge of the sun, appears like a line which progressively extends in breadth, till it reaches the middle, when it begins to contract, and ultimately disappears, at the western edge. In some rare instances, the same spots re-appear on the east side, and are permanent for two or three revolutions. But, as a general thing, the spots on the sun are neither permanent nor uniform. Sometimes several small ones unite into a large one ;. and, again, a large one separates into numerous small ones. Some continue several days, weeks, and even months, together; while others appear and disappear, in the course of a few hours. Those spots that are formed gradually, are, for the most part, as gradually dissolved ; whilst those that are suddenly formed, generally vanish as quickly. It is the general opinion, that spots^m the sun were first dis- covered by Galileo, in the beginning OT the year 1611 ; though Scheiner, Harriot, and Fabricius, observed them about the same time. During a period of eighteen years from this time, the sun was never found entirely clear of spots, excepting a few days in December, 1624 ; at other times, they were frequently seen, twenty or thirty at a time, and in 1625, upwards of fifty were seen at once. From 1650 to 1670, scarcely any spots were to be seen; and, from 1676 to 1684, the orb of the sun presented an unspotted disk. Since the beginning of the eighteenth century scarcely a year has passed, in which spots have not been visi- ble, and frequently in great numbers. In 1799, Dr. Herschel observed one nearly 30,000 miles in breadth. A single second of angular measure, on the sun's disk, as seen from the earth, corresponds to 462 miles'; and a circle of this diameter (con- taining therefore nearly 220,000 square miles) is the least space which can be distinctly discerned on the sun as a visible area, even by the most powerful glasses. Spots have been observed, however, whose linear diameter has been more than 44,000 miles ; and, if some records are to be trusted, of even still greater extent. Dr. Dick, in a letter to the author, says, " I have for many years ex- amined the solar spots with considerable^ minuteness, and have several times seen spots which were not less than the one-twenty-fiflh part of the sun's diameter, which would make them about 22,192 miles hi diameter, yet they were visible neither to the naked eye, nor through an opera glass, magnifying about three times. And, therefore, if any spots have been visible to the naked eye which we must believe, unless we refuse T2 222 GEOGRAPHY OF THE HEAVENS. respectable testimony they could not have been much less than 50,000 miles in diameter." The apparent motion of these spots over the sun's surface, is continually varying in its direction. Sometimes they seem to move across it in straight lines, at others in curve lines. These phenomena may be familiarly illustrated in the following manner. Fig. 1. Fig. 2. m w># 19 *i oTUii j