-NRLF 
 
GIFT OF 
 Mr. George N, Brewer 
 

 
- - 
 
" He telleth the number of the Stars, and calleth them all by ther* numes. 
 
 THE 
 
 GEOGRAPHY OF THE HEAVENS, 
 
 AND 
 
 CLASS-BOOK OF ASTRONOMY: 
 
 ACCOMPANIED BY 
 
 A CELESTIAL ATLAS 
 
 BY ELIJAH H. BIJRRITT, A.M. 
 
 QREATLY ENLARGED, REVISED AND ILLUSTRATED, 
 
 tfY H. MATTISON, A. M. 
 
 NEW AND REVISED EDITION. 
 
 NEW YORK: 
 MASON" BROTHERS, 596 
 
 BOSTON: 154 TKEMONT ST. 
 
Entered according to Act of Congress, in the year 1856, by 
 
 V. .1. HUNTINGTON, 
 
 In me Clerk's Office of the District Court of the United States for tli. Southern 
 District of New York. 
 
 ALVORD, PRINTER. 
 
PREFACE. 
 
 THE rapid progress of the science of astronomy, for the liwr. 
 "few years, has again rendered it necessary to revise the Geo- 
 graphy of the Heavens a work, the popularity of which is suffi- 
 ciently proved by a sale of 300,000 copies. The editor has, 
 therefore, availed himself of the occasion to make such improve- 
 ments, both in the book and maps, as seemed to be demanded by 
 the progress of the science, and the most approved methods of 
 instruction. Among these improvements we may mention the 
 following : 
 
 1. The matter of the book has been thoroughly assorted ; the 
 most important paragraphs being printed in large type, and 
 numbered, as in most modern text-books ; while that which 
 seemed in the main explanatory of the more important portions, 
 is left in small print. By this means an agreeable variety is 
 afforded to the eye, while the book is made to contain far more 
 matter, and is, consequently, far more complete, than it could 
 otherwise have been. 
 
 2. A new set of Questions has been prepared throughout. 
 These are brief, topical and suggestive ; and numbered to 
 answer to the paragraphs to which they relate. 
 
 3. A complete list of Telescopic Objects in each constellation 
 has been inserted ; giving the Right Ascension and Declination 
 of each object ; with a brief description of it ; and easy land- 
 marks and directions by which it may be found ; and references 
 to telescopic views of the same in the new maps. The color and 
 relative magnitude of the components of the double stars, are 
 also given. These Telescopic Objects, compiled with great labor 
 from Smyth^ Cycle, of Celestial Oljects, will be found especially 
 
 M530304 
 
IV PREFACE. 
 
 valuable to all institutions having an equatorial telescope 
 Indeed, they greatly enhance the value of the work for al 
 classes of students. 
 
 4. Several small constellations that were delineated on thp 
 maps, but were not described in former editions of the book, 
 have been described, and their history given in the present, 
 edition. 
 
 5. The page of the book has been greatly enlarged, for the 
 double purpose of printing more matter and in larger type : 
 and to afford scope for wood-cut illustrations. Of these, great 
 numbers have been introduced into the second part of the work, 
 adapting it, in this respect also, to the wants of both teacher 
 and student. 
 
 6. Still further to illustrate the second part of the work, the 
 first map of the atlas has been re-drawn and re-engraved, so as 
 to illustrate more and better than the old map. 
 
 7. Two entirely new maps have been introduced into the Atlas, 
 containing views of eighty different celestial objects ; such as 
 Double Stars, Clusters, Nebulae, Comets, &c. These are 
 all referred to in the book, and in turn refer from the objects 
 back to the page of the book where they are described. These 
 maps and the corresponding descriptions in the book will be 
 found not only extremely interesting, but of incalculable value 
 to the student. 
 
 8. A chapter on the history, structure and use of Telescopes, 
 Transit Instruments, &c., has been introduced a subject which 
 every student of astronomy should understand, but one to whicb 
 no attention was given in the previous editions. 
 
 Such are some of the principal new features of the present 
 edition larger type, new questions, telescopic objects, new maps, 
 new matter, and numerous illustrations, making it the most per- 
 lect and complete text-book of astronomy ever offered to the 
 American public. 
 
 H. MATTISON 
 
 New Yorlc, July 18G6. 
 
INDEX TO THE CONSTELLATIONS. 
 
 Andromeda 
 Antinoua .. 
 Anser et Velpecula 
 Aries ... 
 Argo Navis 
 
 PACK 
 
 18 
 
 ... 118 
 . . .121 
 
 . 28 
 62 
 Aquila ....... 118 
 
 Aquarius ...... 131 
 
 Auriga . . . ' . . . .49 
 
 Bootes ....... 84 
 
 Cainelopardalus ..... 51 
 
 Oaucer .......64 
 
 Janes Venatici ..... 83 
 
 Canis Major ...... 59 
 
 Canis Minor ...... 56 
 
 Cupricornqs ...... 121 
 
 Cassiopeia ...... 22 
 
 Centaurus ...... 88 
 
 Cepheus ...... 25 
 
 Cetus ....... 32 
 
 Columba ...... 46 
 
 Coma Berenices ..... 77 
 
 Corvus ....... 78 
 
 Corona Australis ..... 118 
 
 Corona Boreali* .... 94 
 
 Crater . .... 71 
 
 Cygnus ...... .124 
 
 Delphinus . . . . .122 
 
 Draco ....... 110 
 
 Eridanus ...... 47 
 
 Equuleus . ' ..... 131 
 
 Gemini ....... 53 
 
 Gloria Frederica . .134 
 
 Hercules . 103 
 
 Lynx 
 Lyra 
 
 Monoceros 
 Musca . 
 
 Hydra 71 
 
 Lacerta 134 
 
 Leo 66 
 
 Leo Minor 69 
 
 Lupus (The Wolf) .... 90 
 
 Lepus (The Hare) .... 45 
 
 Libra 91 
 
 52 
 
 112 
 
 58 
 
 82 
 
 Nocta 83 
 
 Ophiuchus 107 
 
 Orion 41 
 
 Pegasus 129 
 
 Perseus . . . . . . .35 
 
 Pisces 20 
 
 Pisces Australis . . . . 166 
 
 Sagittarius ... . 116 
 
 Sagitta 121 
 
 Scutum Sobieski lib' 
 
 Scorpio 100 
 
 Sceptrum Braudenburgium ... 49 
 
 Serpentarius vel Ophiuchus . . 107 
 Serpens . . . * . .93 
 
 Sextans 70 
 
 Taurus 38 
 
 Taurus Poniatowski . . . .115 
 
 Telescopium llerschellii ... 53 
 
 Triangulae ...... 31 
 
 Ursa Major 73 
 
 Ursa Minor 96 
 
 Virgo 80 
 
CONTENTS. 
 
 PART I. -THE CONSTELLATIONS. 
 
 
 
 r.tr.u 
 
 CHAPTER I. Constellations on the meridian in November, * 
 
 18 
 
 44 II. 
 
 December, .... 
 
 23 
 
 m. "- " 
 
 January, .... 
 
 38 
 
 it iy u u tt 
 
 February, .... 
 
 52 
 
 14 y^ U 41 II 
 
 March, .... 
 
 62 
 
 u VI. " " '* 
 
 April, . . 
 
 66 
 
 " VIL " " " 
 
 May, . . . ^ 
 
 73 
 
 u vill. 
 
 June, .... 
 
 84 
 
 44 IX. 
 
 July, .... 
 
 100 
 
 44 X. 
 
 August, .... 
 
 110 
 
 ti xi. u u it 
 
 September, .... 
 
 122 
 
 u XII. " " " 
 
 October, .... 
 
 129 
 
 u XIII. Variable and Double Stars Clusters and Nebulae, .... 
 
 135 
 
 " XIV. Via Lactea, or Milky- Way 
 
 
 141 
 
 " XV. Origin of the Constellations, 
 
 ........ 
 
 143 
 
 " XVI. Number, Distances and Econc. 
 
 
 148 
 
 " XVII. Falling, or Shooting Stars, . . . . . . . 
 
 154 
 
 PART II. -THE SOLAR SYSTEM. 
 
 CHAPTER I. General Phenomena of the Solar System, History, Ac., . . 163 
 
 " H. The Sun His Distance, Magnitude, Ac., ..... 171 
 
 ** HI. The Primary Planets Mercury, Venus, Ac., ..... 177 
 
 " IV. The Moon Her Distance, Motions, Phases, Ac., .... 203 
 
 * V. Solar and Lunar Eclipses, ......... 214 
 
 " VI. Primary Planets continued Mars and the Asteroids, . . . 224 
 
 " VII. Primary Planets Jupiter and Saturn, ..... . 233 
 
 Vni. Primary Planets Uranus and Neptune, .... . 245 
 
 ' IX. Comets Their Nature, Motions, Orbits, Ac., ..... 249 
 
 " X. Of the Forces by which the Planets are retained in their Orbits, ' . 2C2 
 
 " XI. Proper Motion of the Sun in Space, ....... 268 
 
 " XII. Precession of the Equinoxes Obliquity of the Ecliptic, . . .210 
 
 " XIII. Philosophy of the Tides, ......... 280 
 
 " XIV. The Seasons Different Lengths of the Days and Nights, . . 287 
 
 " XV. The Harvest Moon, and Horizontal Moon, ..... 293 
 
 " XVI. Refraction and Twilight, ......... 297 
 
 ' XVII. Aurora Borealis and Parallax, ........ 302 
 
 "XVIII. Practical Astronomy Reflection and Rel action of Light, . . 308 
 
 " XIX. Refractors and Rejectors, ... ..... 813 
 
 M XX. Problems and Tables, .... 33J 
 
INTRODUCTION 
 
 1. ASTRONOMY is the science of the heavenly bodies the Sun, 
 Moon, Planets, Comets, and Fixed Stars. 
 
 2. In entering upon this study, the phenomena of the hea- 
 vens, as they appear on a clear evening, are the first objects that 
 demand our attention. Our first step is to learn the names and 
 positions of the heavenly bodies, so that we can identify, and 
 distinguish them from each other. 
 
 In this manner they were observed and studied ages before books were written, and it 
 was only after many careful and repeated observations, that systems and theories of 
 Astronomy were formed. To the visible heavens, then, the attention of the pupil should 
 be first directed, for it is only when he shall have become, in some measure, familiar 
 with them, that he will be able to locate his Astronomical knowledge, or fully compre- 
 hend the terms of the science. 
 
 3. For the sake of convenient reference, the heavens were 
 early divided into constellations, and particular names assigned 
 to the constellations and to the stars which they contain. A 
 constellation may be defined to be a cluster or group of stars 
 embraced in the outline of some figure. These figures are, in 
 many cases, creations of the imagination ; but in others, the 
 stars are in reality so arranged as to form figures which have 
 some resemblance to the objects whose names have been assigned 
 to them. 
 
 These divisions of the celestial sphere bear a striking analogy to the civil divisions of 
 the globe. The constellations answer to states and kingdoms, the most brilliant clus- 
 ters to towns and cities, and the number of stars in each, to their respective population. 
 The pupil cap trace the boundaries of any constellation, and name all its stars, one by 
 one, as readily as he can trace the boundaries of a state, or name the towns and cities 
 from a map of New England. In this sense, there may be truly said to be a Geography 
 of the Heavens. 
 
 4. The stars are considered as forming, with reference to 
 
 1. What is Astronomy? 2. What first studied? First step? 3. How are t^ie 
 heavens divided, and why? What is a constellation ? Wh.it of these figures ? Iu what 
 sense may there really be a " Geography of the heaventV 4. How are the star-j 
 classified, as respects their magnitude? What expedient for uesignatiu 5 their places 
 tu the heavens? 
 
10 ASTRONOMY. 
 
 their magnitudes, sixteen classes ; the brightest being called 
 stars of the first magnitude, the next brightest, stars of the 
 second magnitude, and so on to the sixth class, which consists 
 of the smallest stars visible to the naked eye. The next ten 
 classes are seen only through telescopes. 
 
 In order to be able to designate with precision their situa- 
 tions, imaginary circles have been considered as drawn in the 
 heavens, most of which correspond to, and are in the same plane 
 with, similar circles, supposed for similar purposes, to be drawn 
 on the surface of the Earth. 
 
 5. In order to facilitate the study of Astronomy, artificial 
 representations of the heavens, similar to those of the surface of 
 the Earth, have been made. Thus, a Celestial Atlas, composed 
 of several maps, accompanies this work. Before, however, pro- 
 ceeding to explain its use, it is necessary to make the pupil 
 acquainted with the imaginary circles alluded to, called the Cir- 
 cles of the Sphere. 
 
 CIRCLES OF THE SPHERE. 
 
 6. The Axis of the Earth is an imaginary line, passing through 
 its centre, north and south, about which its diurnal revolution is 
 performed. 
 
 The Poles of the Earth are the extremities of its axis. 
 
 The Axis of the Heavens is the axis of the Earth produced 
 both ways to the concave surface of the heavens. 
 
 The Poles of the Heavens are the extremities of their axis. 
 
 The Equator of the Earth is an imaginary great circle pass- 
 ing round the Earth, east and west, everywhere equally distant 
 from the poles, and dividing it into northern and southern hemi- 
 bpheres. 
 
 The Equator of the Heavens, or Equinoctial, is the great circle 
 formed on the concave surface of the heavens, by producing the 
 plane of the Earth's equator. 
 
 A plane is that which has surface but not thickness. The plane of a circle is that ima- 
 ginary superficies which is bounded by the circle. 
 
 7. The Rational Horizon is an imaginary great circle, whose 
 plane, passing through the centre of the Earth, divides the hea- 
 vens into two hemispheres, of which the upper one is called the 
 
 5. What helps to facilitate the study of the heavens? Circles? Called what? 
 6. Axis of the Earth ? Poles? Axis of the heavens? Poles of the heavens? Equator 
 of the Earth ? Equator of tha heavens, or Equ noctial ? 7. Rational horizon ? Sensi- 
 ble or apparent f 
 
CHICLES OF THE SPHERE. II 
 
 visible hemisphere, and the lower one, the invisible hemisphere. 
 It is the plane of this circle which determines the rising and set- 
 ting of the heavenly bodies. 
 
 The Sensible or Apparent Horizon, is the circle which termi- 
 nates our view, where the Earth and sky appear to meet. 
 
 To a person standing on a plain, this circle is but a few miles in diameter. If the eye 
 he elevated five feet, the radius of the sensible horizon will be less than two miles and 
 three quarters ; if the eye be elevated six feet, it will be just three miles. The observer 
 being always in the centre of the sensible horizon, it will move as he moves, and enlarge 
 or contract, as his station is elevated or depressed. 
 
 8. The Poles of the Horizon are two points, of which the one is 
 directly overhead, and is called the Zenith ; the other is directly 
 underfoot, and is called the Nadir. 
 
 Vertical Circles are circles drawn through the Zenith and 
 Nadir of any place, cutting the horizon at right angles. 
 
 The Prime Vertical is that which passes through the east and 
 west points of the horizon. 
 
 9. The Ecliptic is the plane of the Earth's orbit ; or the great 
 circle which the Sun appears to describe annually among the 
 stars. It crosses the Equinoctial, a little obliquely, in two oppo- 
 site points, which are called the Equinoxes. The Sun rises in 
 one of these points on the 21st of March ; this point is called 
 the Vernal Equinox. It sets in the opposite point on the 23d 
 of September ; this point is called the Autumnal Equinox. One 
 half of the Ecliptic lies on the north side of the Equinoctial, the 
 other half on the south side, making an angle with it of 23. 
 This angle is called the obliquity of the Ecliptic. The axis of 
 the Ecliptic makes the same angle with the axis of the heavens; 
 so that the poles of each are 23-j- apart. 
 
 This angle is perpetually decreasing. At the commencement of the Christian era, it 
 was about 23* 45'. At the beginning of 1836, it was oniy 23* 27' 88", showing an annual 
 diminution of about half a second, or 46".70 in a hundred years. A time will arrive, 
 however, when this angle, having reached its minimum, will again increase in the same 
 ratio that it had before diminished, and thus it will continue to oscillate at long periods, 
 between certain limits, which are said to be comprised withiu the space of 20 42'. 
 
 10. The Ecliptic, like every other circle, contains 360, and it 
 irf divided into 12 equal arcs of 30 each, called signs, which the 
 ancients distinguished by particular names. This division com- 
 mences at the vernal equinox, and is continued eastwardly round 
 to the same point again in the following order : Aries, Taurus, 
 Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capri- 
 
 8. Poles of the horizon? Vertical circles? Prime Vertical ? 9. Ecliptic? Equi- 
 noxes? How is the Ecliptic situated with respect to the Equinoctial? Obliquity of 
 Ecnptic? Is this angle permanent? 10. How is the Ecliptic divided? Where com- 
 UM-uced, and how reckoned? Name sigl 3 in order ? How does the Sun proceed tb: ,ugu 
 Ih. signs? 
 
 1* 
 
12 ASTRONOMY. 
 
 COTIUS, Aquarius, Pisces. The Sun, commencing at the first 
 degree of Aries, about the 21st of March, passes, at a mean 
 rate, through one sign every month. 
 
 11. The Zodiac is a zone or girdle, about 16 degrees in breadth, 
 extending quite round the heavens, and including all the heavenly 
 bodies within 8 on each side of the ecliptic. It includes, also, 
 the orbits of all the planets, except some of the asteroids, since 
 they are never seen beyond 8 either north or south of the ecliptic. 
 
 12. Parallels of Latitude, are small circles imagined to be 
 drawn on the Earth's surface, north and south of the equator, 
 and parallel to it. 
 
 Parallels of Declination are small circles, imagined to be drawn 
 on the concave surface of the heavens, north and south of the 
 equinoctial, and parallel to it ; or they may be considered as 
 circles formed by producing the parallels of latitude to the 
 heavens. 
 
 13. The Tropic of Cancer is a small circle, which lies 23 
 north of the Equinoctial, and parallel to it. The Tropic of 
 Capricorn is a small circle, which lies 23^- south of the Equi- 
 noctial, and parallel to it. On the celestial sphere, these two 
 circles mark the limits of the Sun's farthest declination, north 
 and south. On the terrestrial sphere, they divide the torrid from 
 the two temperate zones. That point in the ecliptic which 
 touches the tropic of Cancer, is called the Summer Solstice ; and 
 that point in the ecliptic which touches the tropic of Capricorn, 
 is called the Winter Solstice. 
 
 The distance of these two points from the equinoctial, is always equal to the obliquity 
 of the ecliptic, which, in round numbers, is 23c ; but, as we have seen, the obliquity o f 
 the ecliptic is continually changing; therefore the position of the tropics must make ; 
 correspondent change. 
 
 14. The Colures are two great circles which pass through the 
 poles of the heavens, dividing the ecliptic into four equal parts, 
 and mark the seasons of the year. One of them passes through 
 the equinoxes, at Aries and Libra, and is thence called the Equi- 
 noctial Colure; the other passes through the solstitial points or 
 the points of the Sun's greatest declination north and south, and 
 is thence called the Solstitial Colure. 
 
 The Sun is in the equinoctial points the 21st of March and the 23d of September. He 
 in the solstitial points the 22d of June and the 22d of December. 
 
 15. The Polar Circles are two small circles, each about 66| 
 
 11. (.What is the Zodiac? 12. Parallels of latitude? Of declination? ]R. Th<? 
 tropics? Cancer? Capricorn? What do these circles mark in the celestial sphere* 
 O; k % > terrestrial ? 14. The Colures? Where situated ? When is the Sun at the eqm- 
 Loetia, K '-its? The solsticial? 15. What are the Polar Circles? 
 
CIRCLES OF THE SPHERE. 13 
 
 from the equator, being always at the same distance from the poles 
 that the tropics are from the equator. The northern is called 
 the Arctic circle, and the southern the Antarctic circle. 
 
 16. Meridians are imaginary great circles drawn through the 
 poles of the world, cutting the equator and the equinoctial at 
 right angles. 
 
 Every place on the Earth, and every corresponding point in the heavens, is considered 
 as having a meridian passing through it; although astronomers apply but 24 to the 
 heavens, thus dividing the whole concave surface into 24 sections, each 15* in width. 
 These meridians mark the space which the heavenly bodies appear to describe, every 
 hour, for the 24 hours of the day. They are thence sometimes denominated Hour Circles. 
 
 In measuring distances and determining positions on the Earth, the equator and some 
 fixed meridian, as that of Greenwich, contain the primary starting points; in the hea- 
 vens these points are in the ecliptic, the equinoctial, and that great meridian which 
 passes through the first point of Aries, called the equinoctial colure. 
 
 17. Latitude on the Earth, is distance north or south of the 
 equator, and is measured on the meridian. 
 
 Latitude in the Heavens, is distance north or south of the eclip- 
 tic, and at right angles with it. 
 
 Longitude on the Earth, is distance either east or west from 
 some fixed meridian, measured on the equator. 
 
 Longitude in the Heavens, is distance east from the first point 
 of Aries, measured on the ecliptic. 
 
 18. Declination is the distance of a heavenly body either north 
 or south of the equinoctial, measured on a meridian. 
 
 Right Ascension is the distance of a heavenly body east from 
 the first point of Aries, measured on the equinoctial. 
 
 It is more convenient to describe* the situation of the heavenly bodies by their decli- 
 nation and right ascension, than by their latitude aud longitude, since the former cor- 
 responds to terrestrial latitude and longitude. 
 
 Latitude and declination may extend 90 and no more. Terrestrial longitude may 
 extend ISO* either east or west; but celestial longitude and right ascension, being reck- 
 oned in only one direction, extend entirely round the circle, or 360. 
 
 It is easy to convert ripht ascension into time, or fine into right ascension, foi if a 
 heavenly body is one hou: in passing over 15, it will be one fifteenth of an hour, or four 
 minutes, in passing over 1*. 
 
 If the first point of Aries be on the meridian at 12 o'clock, the next hour line, whicn 
 is 15" E. of it, will cqme to the meridian at 1 o'clock; the second hour line at 2 o'clock; 
 the third at 3, &c. Of any two bodies whose right ascensions are given, that one will 
 pass the meridian Jirat which has the least right ascension. 
 
 19. In consequence of the Earth's motion .eastward in its 
 orbit, the stars seem to have a motion westward, besides their 
 apparent diurnal motion caused by the Earth's revolution on its 
 axis ; so that they rise and set sooner every succeeding day by 
 about four minutes, than they d : d on the preceding. This is 
 
 16. Meridians? How many? What other name? How measure distances on the 
 earth? In the heavens? 17. What is latitude on the earth? In the heavens? 
 Longitude on the earth? In the heavens? 13. Declination ? Right ascension 
 Why describe by I), and R. A.? Extent of latitude? Declination? Longitude and R 
 A ? flow convert R. A. into time? Which of two bodies given will first pass the meri- 
 Jian? 19 What a 'parent motion of stars? Cause ? Results?) 
 
14 ASTRONOMY. 
 
 called their daily acceleration. It amounts to just two hours a 
 month. On this account we have not always the same constel- 
 lations visible to us throughout the year. While some, that were 
 not visible before, are successively rising to view in the east, and 
 ascending to the meridian, others sink beneath the western 
 horizon, and are seen no more, until, having passed through the 
 lower hemisphere, they again reaopear in the east. 
 
 DESCRIPTION AND USE OF THE MAPS. 
 
 20. THE first map of the atlas represents, upon a large scale, 
 n general view of the solar system. This will be more fully 
 described in the second part of the work. 
 
 The next six maps represent different sections of the concave 
 surface of the heavens. The first of these exhibits the principal 
 constellations visible to us in October, November, and Decem- 
 ber ; the second, those visible in January, February, and March; 
 the third, those visible in April, May, and June ; and the fourth, 
 those visible in July, August, and September ; with the excep- 
 tion, however, of the constellations which lie beyond the 50th 
 degree of north and south declination, of which, indeed, those 
 around the North Pole are always, and those around the South 
 Pole, never visible to us. 
 
 21. These constellations are represented on the sixth and 
 seventh maps, called circumpolar maps, which are an exact con- 
 tinuation of the others, and if joined to them at their correspond- 
 ing degrees of right ascension and decimation, they might be 
 considered as constituting one map. The scale on which all the 
 above-mentioned maps are drawn is that of a 16-inch globe. 
 The lines drawn on the maps have been already defined ; and 
 their use, being nearly the same with those in geography, will 
 be readily understood. Those which are drawn from right to 
 left, on each side of the equinoctial and parallel to it, are called 
 Parallels of Declination. Those which are drawn up and down 
 through the maps, at intervals of 15, are called Meridians of 
 Right Ascension, or Hour Circles. 
 
 The scale at the top and bottom of the first four maps, and in the circumference o;* 
 the circumpolar maps, indicates the daily progress of the stars in right ascension, and 
 shows on what day of the month any star will be on the meridian at 9 o'clock in tht 
 evening. 
 
 20. What said of maps? First? Next six? 21. Sixth and seventh? Scale? 
 Describe lines? S-ale indicates what? 
 
CLASSIFICATION OF STARS, NEBLL^E, ETC. 15 
 
 22. The first four maps of the heavens are so constructed 
 that the pupil in using them must suppose himself to face the 
 south, and to hold them directly overhead in such manner that 
 the top of the map shall be towards the north, and the bottom 
 towards the south ; the right hand side of the map will then be 
 west, and the left-hand east. In using the circumpolar maps he 
 must suppose himself to face the pole, and to hold them in such 
 a manner that the day of the given month shall be uppermost. 
 
 The constellation called the Great Bear is ~ exception to this rule; in this constel- 
 lation the principal stars are marked in the order of their right ascension. 
 
 That point of projection for the maps which would exhibit each successive portion of 
 the heavens directly overhead at 9 o'clock in the evening, was chosen, because in sum- 
 mer at an earlier hour the twilight would bedim our observation of the stars, and a. 
 other seasons of the year it is easier to look up to stars that want an hour of their 
 meridian altitude than to those which are directly overhead. 
 
 CLASSIFICATION OF STARS, NEBULA &c. 
 
 23. FOR purposes of convenience in finding or referring to par- 
 ticular stars, recourse is had to a variety of artificial methods 
 of classification. First, the whole concave of the heavens is 
 divided into sections or groups of stars, of greater or less extent, 
 called Constellations. (Of the origin of these figures see page 
 143). Next, they are classified according to their magnitudes, 
 (as already stated art. 4), and designated on the maps accord- 
 ingly. Thirdly, the stars of each constellation are classified 
 according to their magnitudes in relation to each other, and with- 
 out reference to other constellations. Thus, for instance, the 
 largest star in Taurus is marked a, Alpha ; the next largest /?, 
 Beta; the next, j, Gamma, &c., till the Greek alphabet is 
 exhausted. Then the Roman (or English) is taken up, and 
 finally, if necessary, recourse is had to figures. 
 
 This useful method of designating particular stars by the use of the Greek and Roman 
 alphabet, was invented by John Bayer, of Augsburg, in Germany, in 1603. It has been 
 adopted by all succeeding astronomers, and extended by the addition of the Arabic 
 notation 1, 2, 8, &c., wherever the stars in a constellation outnumber both alphabets. 
 
 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 capitals are seldom used for designating the stars, but are 
 here given for the sake of regularity. 
 
 22. How use the first four maps of the hear ens? Circumpolar? What exception? 
 What point of projection chosen, and why? 23 Classification or designation of 
 i*tars? By whom invented, and when? 
 
16 ASTRONOMY. 
 
 THE GREEK ALPHABET. 
 
 A a Alpha N v Nu 
 
 li /? Beta S , c Xi 
 
 F y Gamma O o Omicron 
 
 A <5 Delta II * Pi 
 
 E e Epsilon P p Rho 
 
 Z C Zeta 2 f Sigma 
 
 H T] Eta T T Tau 
 
 6 e Theta ^ Y v Upsilon 
 
 I t Iota $ (/> Phi 
 
 K K Kappa X j Chi 
 
 A A Lambda * V' Psi 
 
 M /* Mu Q w Omega 
 
 24 As a further aid in finding particular stars, and especially 
 in determining their number, and detecting changes, should any 
 occur, catalogues of the stars have been constructed, one of 
 which is over two thousand years old. Several of the principal 
 stars have specific names, like the planets, as Sirius, Aldebaran, 
 Regulus, <fcc. 
 
 25. The stars are still further distinguished, as single, double, 
 triple, multiple, Unary, variable, 'new, ami nebulous. 
 
 A single star is one that appears as a unit under the most 
 powerful telescopes. Double, triple, and multiple stars, are those 
 that appear single to the naked eye, but by the aid of telescopes 
 are found to consist of two or more stars. Binary stars are 
 double stars revolving around each other, often called Binary 
 Systems. Variable stars are those that are found to undergo 
 certain fluctuations in their brightness, sometimes becoming quite 
 invisible. In most cases these changes are periodical and 
 regular, on which account they are called Periodical stars. 
 New stars are those that suddenly blaze forth in some portion 
 of the heavens previously void. Nebulous stars are those which 
 are surrounded by a faint nebula, or halo of light or mist. 
 
 26. A duster of stars is an assemblage or Jronp, thrown 
 promiscuously together, like the fflgiides and Hyades in Taurus, 
 and the Bee Hire in Cancer. Ko'iNebiita is a cluster so remote 
 as to appear only like a faint cloud *or r hsfate of. light. Resolvable 
 Nebula, are those that can be resolved 9 j$fco distinct stars by the 
 aid of a telescope. Irresolvable Nebulce are those that have not 
 
 24. What further aid? Age? Names of stars? 25. Stars, how further distia 
 pnished? Single Ftars? Double, Ac.? Binary? What other name? Variable stars. 
 VVhHt other name and why? New stars? Nebulous? 26. What are clusters ? Ncbu 
 W? Resolvable Nebula?'? Irresolvable ? Annular? Planetary? 
 
CLASSIFICATION OF STARS, NEBULAE, ETC. 17 
 
 as- ye- been thus resolved. Annular Nebula are those that have 
 the form of an annulus or ring. Planetary Nebula are those 
 that resemble planets in form, and in the sharpness of their out- 
 line. Stellar Nebula are those with a star in the centre, the 
 same as nebulous stars, already described (25). 
 
 A more detailed account of the double stars, clusters and nebulae, will be given after 
 the student has become somewhat familiar with the constellations. 
 
 21. We may now imagine the pupil roady to begin the study 
 of the visible heavens. The first thing of importance is to fix 
 upon the proper starting point. This, on many accounts, would 
 seem to be the North Polar Star. Its position is apparently 
 the same every hour of the night throughout the year, while the 
 other stars are continually moving. Many of the stars also in 
 that region of the skies never set, so that when the sky is clear, 
 they may be seen at any hour of the night. They revolve about 
 the pole in small circles, and never disappear below the horizon. 
 
 On this account they are said to be within the circle of perpetual apparition. On the 
 other hand, the identity of the North Polar Star, strange as it may appear, is not so 
 easily determined by those who are just entering upon this study, as that of some others. 
 For this reason, the point directly overhead, called the zenith, is preferable, since upon 
 this point every one can fix with certainty in whatever latitude he may be. It will be 
 alike to all the central point of the visible heavens, and to it the pupil will learn imper- 
 ceptibly to refer the bearing, motion, and distances of tne heavenly bodies. 
 
 That meridional point in each map, whose declination corresponds with the latitude 
 of the place of observation, represents the zenith of the heavens at that place; and 
 th^se constellations of stars which occupy this position en the maps, will be seen directly 
 overhead at 9 o'clock in the evening of the day through which the meridian passes. 
 Thus in Georgia, for instance, the starting point should be those stars which are situated 
 in this meridian near the 38d degree of north declination, while in New England it 
 should be those which are situated in it near the 42d degree. 
 
 28. We might, however, begin with the stars near either of 
 the meridians represented on the maps, the only rule of selection 
 being to commence at that which approaches nearest to being 
 overhead at the time required. We have chosen for our starting 
 point in this work that meridian which passes through the vernal 
 er,uinox at the first point of Aries, not only because it is the 
 meridian from which the distances of all the heavenly bodies are 
 measured ; but especially because the student will thus be 
 enabled to observe and compare th? progressive motion of the 
 constellations according to the order in which they are always 
 arranged in catalogues, and also to mark the constellations of 
 the Zodiac passing overhead as they rise one after another in 
 their order, and to trace among them the orbits of the Earth 
 and of the other planets. 
 
 27. What first important in commenc : *ig study of the heavens? What star woulj 
 seem best starting point? Why? Wh> not the best? What point preferable, an 1 
 wliy? Illustration from map. 28. With what stars might we begin? What raerid'un 
 rhoseu by the author? Why* 
 
PART I. 
 THE CONSTELLATIONS 
 
 CHAPTER I. 
 
 CONSTELLATIONS ON THE MERIDIAN IN NOVEMBER 
 
 ANDROMEDA. MAP II.* 
 
 29. IF we look directly overhead 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 Triangles and 
 the Northern Fish. It is situated between 20 and 50 of K. 
 decimation. Its mean right ascension is nearly 15; or one 
 hour E. of the equinoctial colure. 
 
 30. It consists of 66 visible stars, of which three are of the2d 
 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 pre- 
 sence of the moon, but the bright star Almaack (y), of the 2d 
 magnitude, in the left foot, may be seen 13 due E., and Merach 
 ((3), of the same magnitude, in the girdle 7 south of the 
 zenith. This star is then nearly on the meridian, and with two 
 others N.W. of it forms the girdle. 
 
 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 
 Merach, Mu, and Nu. 
 
 31. If a straight line, connecting Almaack with Merach, be 
 
 * As the eastward motion of the earth in her orbit causes the sun to pass eastward 
 annually around the heavens, and the constellations to rise earlier and earlier (19), the 
 student will find it necessary to proceed eastward around the heavens, in studying the 
 constellations. And as the right hand of the map is west, and the left hand east, we 
 begin with the equinoctial colure, map II., and proceed to the left in the order in which 
 the constellations successively arise. 
 
 29. What constellation? Maps, and why? (Note.) How Andromeda, represented? 
 Boundaries? Situation? Right ascension and declination? 8<>. Number of stars 
 Magnitude? Almaack? Merach? "Girdle?" 31. Situation of Delta ? Magnitude 
 to\v otherwise known? Alpheratz? Substance of note ^fine prmt)? 
 
ANDROMEDA. 19 
 
 produced south -westerly, 8 farther, it will reach to (8) Ddta, 
 a star of the 3d magnitude in the left breast. This star may be 
 otherwise known by its forming a line, N. and S., with two 
 smaller ones oil either side of it ; or, by its constituting, with 
 two others, a very small triangle, S. of it. 
 
 Nearly in a line with Almaack, Merach and Delta, but curv- 
 ing a little to the N. 7 farther, is a lone star of the 2d magni- 
 tude, in the head, called Alpheratz (a). This is the N.E. cor 
 ner of the great " Square of Pegasus," to be hereafter described. 
 
 It will be well to have the position of Alpheratz well fixed in the mind, because it is 
 but one minute west of the great equinoctial colure, or first meridian of the heavens, 
 and forms nearly a right line with Algenify in the wing of Pegasus, 14 d. of it, and with 
 Beta in Cassiopeia, 30 N. of it. If a line, connecting these three stars, be produced, it 
 will terminate in the pole. These three guides, in connection with the North Polar Star, 
 point out to astronomers the position of that great circle in the heavens from which the 
 right ascension of all the heavenly bodies is measured. 
 
 MYTHOLOGICAL HISTORY, 
 
 82. The story of Andromeda, from which this constellation derives its name, is as follows: 
 She was daughter of Cepheus, King of Ethiopia, by Cassiopeia. She was promised in 
 marriage to Phineus, her uncle, when Neptune drowned the kingdom, and sent a sea 
 monster to ravage the country, to appease the resentment which his favorite nymphs 
 bore against Cassiopeia, because she had boasted herself fairer than Juno and the 
 Nereides. The oracle of Jupiter Ammon was consulted, and nothing could pacify the 
 anger of Neptune unless the beautiful Andromeda should be exposed to the sea monster. 
 She was accordingly chained to a rock for this purpose, near Joppa (now Jaffa, in Syria), 
 and at the moment the monster was going to devour her, Perseus, who was then return- 
 ing through the air from the conquest of the Gorgons, saw her, and was captivated by 
 her beauty. 
 
 "Chained to a rock she stood ; young Perseus stay'd 
 His rapid flight, to woo the beauteous maid." 
 
 He promised to deliver her and destroy the monster if Cepheus would give her to 
 him in marriage. Cepheus consented, and Perseus instantly changed the sea monster 
 into a rock, by showing him Medusa's head, which was still reeking in his hand. The, 
 enraged Phineus opposed their nuptials, and a violent battle ensued, in which he, also, 
 was turned into a stone, by the petrifying influence of the Gorgon's head. 
 
 The morals, maxims, and historical events of the ancients, were usually communicated 
 in fable or Allegory. The fable of Andromeda and the sea monster might mean that she 
 was courted by some monster of a sea-captain, who attempted to carry her away, but 
 was prevented by another more gallant and successful rival. 
 
 TELESCOPIC OBJECTS. 
 
 33. Under the head of Telescopic Objects, will be included clusters and nebulae that 
 are visible to the naked eye, as well as the principal objects of interest that are strictly 
 telescopic. In describing the location of these objects, R. A. will denote Right Ascen- 
 sion; and Dec., Declination. The initials N. and S. will indicate whether the 
 declination is North or /South of the equinoctial. 
 
 In describing the location of the telescopic object, the R. A. will be given in time, 
 viz., in hours, minutes, and seconds, instead of degrees, minutes, and seconds: each 
 hour answering to 15. The hour circles are listinctly drawn on all tlie maps, the first 
 being 15 east of the equinoctial colure (Map H.), and so on eastward to the same point 
 again. The hours will be seen marked just under the equinoctial, which is marked oft 
 into degrees, each of which answers to four minutes of time. The student will soon find 
 it much more convenient to reckon R. A. by /tours, on the maps, than by degrees, &c. 
 
 32. HISTORY . What may it have meant ? 
 
 33. What included among Telescopic Objects? What meant by R. A.? Dec.? N. ana 
 8.? How R. A. laid down? How on map? What mode of describing components of 
 double stars? Of a Andromeda ? Of discrepancies between R. A. given, and loca- 
 tion of stars on the maps? How is R. A. {riven in locating objects? Why? Ho* 
 are hours marked on the maps? The minutes? 
 
20 ASTRONOMY. 
 
 84. In consequence of the perpetual recession of the equinoxes westward, the R. A. 
 of objects is constantly increased by about 50" per year. It is vain, therefore, to attempt 
 tc give R. A. for the Ume when a book will be us^d; or to construct maps that will 
 show objects in their true place, for different years to come. The necessary allowance 
 jmst be made in all cases ; so that the R. A. for one epoch is about as good as another. 
 The R. A. here given is from Smyth's Celestial Cycle, epoch Jan. 1, 1840. Maps should 
 be re-engraved every fifty years, but for all shorter periods allowance can be made by 
 the student. As the maps accompanying this work were drawn and engraved in. 1835, 
 their present R. A. (1854) is about 17' or 4m. of time east of their places on the maps. 
 
 35 The order in which the telescopic objects will be arranged is first the double stars ; 
 secondly, clusters ; and lastly the nebulas. The double stars will be classed according, 
 to their order in the respective constellations; i.e., a first, /? next, &c. Thus, as the 
 largest objects are first named, the student can begin with those easiest found, a/id 
 requiring the least telescopic power; and proceed from the easier to those more diffi- 
 cult. The same plan is generally pursued with the clusters and nebulae. 
 
 TELESCOPIC OBJECTS IN ANDROMEDA. 
 
 1. a ANDROMEDA (Alpheratz) A star with a minute companion, R. A. Oh. Om. 08s.. 
 Pec., N. 28 12' 05". A. 1, bright white ; B. 11, purplish. On the map it is west of the 
 equinoctial, the map having been engraved some twenty years ; but the equinox having 
 constantly receded westward, had passed Alpheratz before 1840, some 8'. Similar dis- 
 crepancies between the R. A. given and the location of different stars on the map, are 
 due to the same cause. 
 
 2. ft ANDROMEDA (Merach) A bright star with a distant telescopic companion, R. A. 
 Ih. 00m. 4Ts. ; Dec., N. 34 46' 08'. A. 2, fine yellow ; B. 12, pale blue, with several small 
 stars in the field. 
 
 3. y ANDROMEDA (AlmuacK) A SPLENDID DOUBLE STAR on the right foot, R. A. Ih. 54m. 
 06s; Dec. N. 41 33' 06". A. 3}, orange color ; B. 5J$, emerald green. Found by a line 
 from 6 to /3, and about twice as far beyond. (Map VIII., Pig. 1.) 
 
 4. fj ANDROMEDA A bright star on the right breast, with a distant telescopic com- 
 panion, R. A. Oh. 30m. 47s. ; Dec., N. 29 59' 01". A. 3, t range; B. llfc, dusky ; with the 
 small stars in the southern part of the field. 
 
 5. K ANDROMEDA A wide, but delicate TRIPLE STJR, in the northern hand ; midway 
 between Pegasi and a. Cassiopeia ; or about 18 from each ; R. A. 23h. 32m. 83s ; Dec., 
 N. 43 27' 0". A. 5, brilliant white; B. 14, dusky; C. 12, ash-colored. 
 
 6. AN ELONGATED NEBULA on the lady's right foot. R. A,2h. 12m. 35s. ; Dec., N.4J" 36". 
 It was discovered by Miss Caroline Herschell, in 1783. Sir William Herschell described 
 it as having "a black division or chink in the middle." He regarded it as a flat ring 
 of enormous dimensions, seen very obliquely. Captain Smyth says: "In my telescope 
 it is certainly brighter at the edges than along the central part." See map VIII., Fig. 21. 
 
 7. About 2 from Nu at the north-western extremity of the girdle, R. A. 00 34m. 05s., 
 N. Dec., 40 23' 06", is n. remarkable nebula of very minute stars, and the only one of 
 the kind which is ever visible to the naked eye. 'It resembles two cones of light, joined 
 at their base, about % in length, and \ in breadth. It was known as far back as A.D. 
 905, is of an oval shape, and is described by Smyth as "an overpowering nebula, with 
 a companion about 25' in the south vertical." Sir William Herschell considered this the 
 nearest of all the great nebulae, and yet so remote thai it would require 6,000 years for 
 light to pass from it to our system, though flying at the rate of 190,000 miles per second 1 
 Fig. 22, map VIII., is a representation of this object. 
 
 PISCES (THE FISHES). MAP Y. 
 
 36. This constellation is now the first in order of the twelve 
 constellations of the Zodiac, and is usually represented by two 
 fishes tied a considerable distance apart, at the extremities of a long 
 undulating cord, or ribbon. It occupies a large triangular space 
 
 84. What said of tir s change of R. A. of objects? Cause? Epoch of R. A. given iu 
 book? Of that marked on maps? Allowance to be made in finding objects by maps 
 &5. Order in which objects are presented ? Advantage of this arrangement? 
 
 TELESCOPIC OBJECTS. What double stars? a? /3? >? What clusters T nebului 
 yi,(7wn on map, or not? 
 
 ?-. Pisces? Where situated? What now callel 9 
 
PISCES. i>l 
 
 m the heavens, and its outline at first is somewhat difficult to be 
 traced. 
 
 In consequence of the annual precession of the stars, the constellation Pisces has now 
 oome to occupy the sign Aries ; each constellation having advanced one whole sign in 
 the order of the Zodiac. The Sun enters the sign Pisces, while the Earth enters that of 
 Virgo, about the 19th of February, but he does not reach the constellaUon Pisces before 
 the 6th of March. The Fishes, therefore, are now called the " Leaders of the Celestial 
 Hosts." See Aries. 
 
 3t. That loose assemblage of small stars directly south of 
 Merach, in the constellation of Andromeda, constitutes the 
 Northern Fish, whose mean length is about 16, and breadth, 
 7. Its mean right ascension is 15, and its declination 25 N. 
 Consequently, it is on the meridian the 24th of November ; and 
 from its breadth, is more than a week in passing over it. 
 
 38. The Northern Fish and its ribbon, beginning at Merach, 
 may by a train of small stars, be traced in a S. S. easterly direc- 
 tion, for a distance of 33, until we come to the star El liischa, 
 of the 3d magnitude, which is situated in the node, OT flexure of 
 the ribbon. This is the principal star in the constellation, and 
 is situated 2 N. of the equinoctial, and 53 minutes east of the 
 meridian. 
 
 Seven degrees S. E. of El Rischa, passing by three cr four very small stars, we come to 
 Mira, in the whale, a star of about the 8d magnitude, and known as the " Wonderful 
 Star of 1596." El Rischa may be otherwise identified by means of a remarkable cluster 
 of five stars in the form of a pentagon, about 15 E. of it. See Cetus. 
 
 39. From El Rischa the ribbon or cord makes a sudden 
 flexure, doubling back across the ecliptic, where we meet with 
 three stars of the fourth magnitude situated in a row 3 and 4 
 apart, marked on the map Zeta, Epsilon,-. Delta. From Delta 
 the ribbon runs north and westerly along the Zodiac, and termi- 
 nates at Beta, a star of the 4th magnitude, 11 S. of Markab 
 hi Pegasus. 
 
 This part of the ribbon, including the Western Fish at the end of it, has a mean 
 declination of 5 N., and may be seen throughout the month of November, passing the 
 meridian slowly to the W., near where the sun passes it on the 1st of April. 
 
 40. Twelve degrees W. of this Fish, there are four small stars 
 situated in the form of the letter Y. The two Fishes, and the 
 cord between them, make two sides of a large triangle, 30 and 
 40 in length, the open part of which is towards the N. W 
 When the Northern Fish is on the meridian, the Western is 
 nearly two hours past it. This constellation is bounded N. by 
 
 87. Northern Fish? Length? Dec.? When on the meridian ? 88. How trace thu 
 Northern Fish? To what star? Magnitude? Where situated? 89. From El Rischa f 
 From Delta? Mean declination of this part of the ribbon? 40. What 12' west o f 
 this fish? ^aat do the two fishos, &c., make? Boundaries of Pisces? 
 
22 ASTRONOMY. 
 
 Andromeda, W. by Andromeda and Pegasus, S. by the Cascade, 
 and E. by the Whale, the Ram and the Triangles. 
 
 When, to enable the pupil to find any star, its direction from another is given, the 
 latter is always understood to be on the meridian. 
 
 After a little experience with the maps, even though unaccompanied by directions, 
 th,j ingenious youth will be able, of himself, t devise a great many expedients and facili 
 ties for tracing the constellations, or selecting out particular stars. 
 
 In using a circumpolar map, face the pole, and hold it up in your hands in such a 
 manner that the part which contains the name of the given month shall be uppermos\ 
 and you will have a portraiture of the heavens as seen at that time. 
 
 The constellations about the Antarctic Pole are not visible in the United States ; 
 those about the Arctic or Northern Pole, are always visible. 
 
 HISTORY. 
 
 41. The ancient Greeks, who have some fable to account for the origin of almos 
 every constellation, say, that as Venus and her son Cupid were one v day on the banks ot 
 the Euphrates, they were greatly alarmed at the appearance of a terrible giant, named 
 Typhon. Throwing themselves into the river, they were changed into fishes, and by 
 this means escaped danger. To commemorate this event, Minerva placed two fishes 
 among the stars. 
 
 According to Ovid, Homer, and Virgil, this Typhon was a famous giant. He had a hun- 
 dred heads, like those of a serpent or dragon. Flames of devouring fire daa-ted from his 
 mouth and eyes. He was no sooner born, than he made war against heaven, and so 
 frightened the gods, that they fled and assumed different shapes. Jupiter became a 
 ram : Mercury, an Ibis ; Apollo, a crow; Juno, a cow; Bacchus, a goat; Pi.na, a cat; 
 Venus, a fish, Ac. The father of the gods, at last, put Typhon to flight, and crushed him 
 under Mount /Etna. 
 
 The sentiment implied in the fable of this hideous monster, is evidently this : that 
 there is in the world a description of men whose mouth is so " full of cursing and bitter- 
 ness," derison and violence, that modest virtue is sometimes forced to disguise itself, 
 or flee from their presence. 
 
 In the Hebrew Zodiac, Pisces is allotted to the escutcheon of Simeon. 
 
 No sign appears to have been considered of more malignant influence than PusMJ. 
 The astrological calendar describes the emblems of this constellation as indicative of 
 violence and death. Both the Syrians and Egyptians abstained from eating fish, 
 out of dread and abhorrence ; and when the latter would represent anything as odious, 
 or express hatred by hieroglyphics, they painted a/w>7t. 
 
 TELESCOPIC OBJECTS. 
 
 1. a PISCICM (El Jfischa) A close double star in the eastern extremity of the ribbon, 
 R. A. Ih. 53m. 46s. ; Dec. N. 1 59' 03'. A. 5, pale green ; B. 6, blue ; a splendid object, 
 and easily found. 
 
 2. PISCIUM A neat double star in the ribbon, about 13 north-west of a, R. A. Ih. 
 5m. 21 s. ; Dec. N. 6 43' 07". A. 6, silvery white ; B. 8, pale gray ; a fine object. 
 
 3. PisciUM-A close double star in the space between the two fishes, about half-way 
 between 7j Andromeda and (j Ceti; R. A. Ih. 2m. 31s. ; Dec. N. 8 42'. A. 8, white; 
 B. 14, pale blue. 
 
 4. A neat DOUBLE STAR, about 4 south of Algenib, in the wing of Pegasus, R. A. Oh- 
 1m. 53s. ; Dec. N. 10 14' 06". A. 6, silvery white ; B. 13J$, pale blue. 
 
 5. A FAINT NEBULA in the eye of the western Fish, about 10 south-half-east of Mar- 
 *ub, near y Piscium; R. A. 23h. 06m. 86s. ; Dec. 8 89' 7" : a very difficult object. 
 
 CASSIOPEIA. MAP VI. 
 
 42. Cassiopeia is represented on the celestial map in regal state, 
 seated on a throne or chair, holding in her left hand the brand) 
 
 41. HISTORY? Greek account? Ovid's and others? Sentiment or moral? Hebre-r 
 Zodiac? Astrology? 
 
 TELESCOPIC OBJECTS. Double stars Clusters? Nebulas? Shown on map, or not? 
 4i. Cassiopeia ? How represented Head? 
 
CASSIOPEIA. <J3 
 
 of a palm tree. Her head and body are seen in the Milky Way. 
 H 2r foot rests upon the Arctic Circle, upon which her chair is. 
 placed She is surrounded by the chief personages of her royal 
 family. The king, her husband, is on her right hand Perseus, 
 her son-in-law, on her left and Andromeda, her daughter, just 
 above her. 
 
 43. This constellation is situated 26 N. of Andromeda, 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 P N. and its right ascension 12. It is on our meridian the 
 22d of November, but does not sensibly change its position for 
 several days ; for it should be remembered that the apparem 
 motion of the stars becomes slower and slower, as they approxi- 
 mate the poles. 
 
 44. Cassiopeia is a beautiful constellation, containing 55 stars 
 that are visible to the naked eye ; of which four are of the 3d 
 magnitude, and so situated as to form, with one or two smaller 
 ones, the figure of an inverted chair. 
 
 " Wide ner stars 
 
 Dispersed, nor shine with mutual aid improved ; 
 Nor dazzle, brilliant with contiguous Same : 
 Their number fifty-five." 
 
 45. Caph, in the garland of the chair, is almost exactly in the 
 equinoctial colure, 30 N.of Alpheratz, 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. Shedir, 
 in the breast, is the uppermost star of the five bright ones, and 
 is 5 S. E. of Caph : 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 Caph that 
 concerns the mariner aad the surveyor. It is used, in connec- 
 tion with observations on the Polar Star, for determining the 
 latitude of places, and for discovering the magnetic variation of 
 the needle. 
 
 46. It is generally supposed that the North Polar Star, so 
 called, is the real immovable pole of the heavens : but this is a 
 mistake. It is so near the true pole that it has obtained the 
 
 43. Situation? How seen? R. A. .and Dec.? When on meridian? 44. Number of 
 stars? Magnitudes? Figure? Character of this constellation? 45. Caph? How 
 situated? When on merid'an? Shedir? Importance attached to Caph? 46. Pole 
 Btar? Is it the tn: e pole? What variation? Uow pole star situated with reference to 
 
JJ4 ASTRONOMY, 
 
 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 elonga- 
 tion E. and W. 
 
 The Polar Star not being exactly in the N. pole of the heavens, but one degree and 
 81 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 equidis- 
 tant froia the pole, and exactly opposite another remarkable star in the square of the 
 Great Bear, on the other side of the pole. [See Megres.] It also serves to mark a spot 
 in the starry heavens, rendered memorable as being the place of a lost star. Two hun- 
 dred and fifty years ago, a bright star shone 6 N. N. E. of Caph, where now is a 
 dark void ! 
 
 On the 8th of November, 15T2, 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 planets, and might be seen even at noonday. Gradually, 
 this great brilliancy diminished, until tho 15th of March, 1573, when, without moving 
 from its place, it became utterly extinct. 
 
 Its color, during this time, exhibited all the phenomena 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 expired. It is impossible, says Mrs. Somerville, to imagine anything 
 more tremendous than a conflagration that could be visible at such a distance. It was 
 seen for sixteen months. Some astronomers imagined that it would reappear 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 con- 
 cerning 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 appear- 
 ance of new stars may be the formation 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 continue to be employed for endless ages ; forming new systems of beings to 
 adore him; and transplanting beings already formed into happier regions, who will con- 
 tinue to rise higher and higher in their enjoyments, and go on to contemplate system 
 after system through th<; boundless universe. 
 
 LA PLACE says : As to those stars which suddenly shine forth with a very vivid light, 
 and then immediately disappear, it is extremely probable that great conflagrations, pro- 
 duced by extraordinary causes, take place on their surface. This conjecture, continues 
 he, 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 gradually extinguished. 
 
 The late eminent Dr. Good also observes that Worlds, and systems of worlds, are cot 
 only perpetually creating, but also perpetually disapoearing. It is an extraordinary fact, 
 that within the period of the last century, not less than thirteen stars, in different con- 
 stellations, seem to have totally perished, 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 different plant ts l>y 
 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 
 incontrovertible ; it is foretold by revelation ; it is inscribed in the heavens ; it is feit 
 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, into Palestine, at the birth of our Saviour, and that it now appeared 
 to announce his second coining. 
 
 Caph ? What other important fact in relation to the position of Caph ? What remark- 
 able fact stated? By whom attested? Describe phenomenon? Mrs. fcoinervtlle'e 
 remark? Other astronomers'? Professor Vince's remarks? The author's? La 
 Place's? Dr. Good's? Beza's? 
 
CEPHET7S. ^ 
 
 HISTORY. 
 
 Cassiopeia was the wife of Cepheus, King of Ethiopia, and mother of Andromeaa. She 
 was a queen of matchless beauty, and seemed to be sensible of it ; for she even boasted 
 herself fairer than Juno, the sister of Jupiter, or the Nereides a name given to the sea- 
 nymphs. This so provoked the ladies of the sea, that they complained to Neptune of the 
 insult, who sent a frightful monster to ravage her coast, as a punishment for her inso- 
 lence. But the anger of Neptune and the jealousy of the nymphs were not thus appeased 
 They demanded, and it was finally ordained that Cassiopeia should chain her daughter 
 Andromeda, whom she tenderly loved, to a desert rock on the beach, and leave her 
 exposed to the fury of this monster. She was thus left, and the monster proached , 
 but just as he was going to devour her, Perseus killed him. 
 "The saviour youth the royal pair confess. 
 And with heav'd hands, their daughter's bridegroom bless." 
 
 JEusden's Ovid. 
 
 TELESCOPIC OBJECTS. 
 
 1. a CASSIOPE.B (Shedir) A bright star, with a companion in the bosom of the figure; 
 R. A Oh. 31m 29s.; Dec. 65 89' 05". A 3, pale rose tint; B 10j, small blue. S-i/th 
 and Herschell note Shedir as variable. 
 
 2. ll CAS8ioPE.fi (Caph)A bright star on the left side, with a minute companion ; 
 R. A. Oh. Om. 42s.; Dec. N. 58" 16' 03". A 2Jj, whitish; B 11^, dusky. Look directly 
 opposite Negris, in the great dipper, through the pole star, and about as far beyond. 
 
 3. y CASSIOPE.K A bright star with a distant companion on the right side of the figure ; 
 R. A. Oh. 47m. 05s. ; Dec. N. 59 50' OS". A 3, brilliant white; B 13, blue. Mar,/ small 
 tars in the field. 
 
 4. 77 CASSIOPE^B A BINARY STAR, about 4 from a towards Polaris ; R. A. Oh. 39m. 27s. , 
 Dec. N. 56 57' 09". A. 4, pale white ; B. 7J*S, purple. Estimated period 700 yeaid. 
 
 5. fi CASSIOPE^B A coarse TRIPLE STAR in the right elbow ; R. A. Oh. 57m. 23s ; Dec. N. 
 54 OS' 01". A 5}$, deep yellow ; B 14, pale blue ; C 11, bluish. Several small slars in the 
 field. 
 
 6. <7 CASSIOPK^ A beautiful double star in the left elbow ; R. A. 23H. 50m. 55s. ; Dec. 
 N. 54 51' OS". A 6, flushed white ; B 8, smalt blue ; the colors clear and distinct. 
 
 7. A coarse QUADRUPLE STAR, just south of Cepheus' right hand; or about 27 south- 
 south-west of Polaris, on a line drawn over y Cepliei. R. A. 23h. 17m. 45s. ; Dec. N. 64' 
 24' 03". A 5, pale yellow ; B 9, yellowish ; C 1 1, and D, 13, both blue. 
 
 8. A LARGE AND STRAGGLING CLUSTER, between the footstool of Cassiopeia and the head of 
 Cepheus; R. A. Oh. ISm. 10s.; Dec. N. 70 30' 08". A line from y Cassiopeze, % the did 
 tance to y Cephei, will fall upon this object. A coarse double star in the field. 
 
 9. A RICH, BUT SOMEWHAT STRAGGLING CLUSTER; R. A. Oh. 24m. 5s. ; Dec. N. 62 23' 09". 
 
 Vicinity splendidly strewed with stars a double star in the centre. Look near the 
 
 star /tr- 
 lO. A LOOSE CLUSTER, including a small double star; R. A. Oh. 34m. 15s.; Dec. N. 60* 
 
 54' 07". A 8 %, B 11, both pale. Situated just half way between y and K. 
 
 11. A LOOSE CLUSTER of small stars ; R. A. Oh. 5Sm. 19s. ; Dec. N. 60" 44'. On a line from 
 y towards f, about J4 the distance. 
 
 12. A CLUSTER and neat double star on a line from a through <J, and about 2J$* beyond. 
 In an elegant field of large and small stars. 
 
 18. A FINE GALAXY CLUSTER of minute stars, about 3* south-west of /?, and about the 
 aame distance west of a. R. A. 23h. 49m. 07s. : Dec. N. 55 49' 06". A glorious assem- 
 blage, both in extent and richness. Resembles a crab, having spangled rays of start?, 
 spreading over many fields = Map VIII., Fig. 23. 
 
 CEPHEUS. MAP VI. 
 
 47. Cepheus is represented on the map as a king, in his royr.1 
 robe, with a sceptre in his left hand, and a orown of stars upcu 
 
 HJTOHY? Who was Cassiopeia? Personal appearance? Sad consequences ? Reacm V 
 TFLKCOPIC OBJECT* Double and multiple stars ? Clusters ? What shown oil map ? 
 47. How is Cepheus represented? Where sjtuated? 
 
26 ASTRONOMY. 
 
 his head. He stands in a commanding posture, with his left 
 foot over the pole, and his sceptre extended towards Cassiopeia, 
 as if for favor and defence 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 Cassiopeia, 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 aJ hours of the night, when the sky is clear, for to us it 
 never sets. 
 
 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 less space in one hour, than one at the equi- 
 noctial; 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, anJ 
 u what the declination wants of 90". 
 
 48. In this constellation there are 35 stars visible to the 
 naked eye ; of these, there glitters on the left shoulder, a star 
 of the 3d magnitude, called Alderamin, which with two others of 
 the same brightness, 8 and 12 apart, form a slightly curved 
 line towards the N. E. The last, whose letter name is Gamma, 
 is in the right knee, 19 N. of Caph, in Cassiopeia. The middle 
 one in the line is Alphirk, 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 direction of one star from 
 another, as given in this treatise, are strictly applicable only when the latter one is on, 
 or near the meridian. The bearings given, in many cases, are not the least approxima- 
 tions to what appears to be their relative position ; and in some, if relied upon, will lead 
 to errors. For example : It is said in the preceding paragraph, that Gamma, in Cepheus, 
 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, Gamma 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 side of the pole, will be 
 within, or beticeen Cassiopeia and the pole that is, west of Cassiopeia. And for the 
 same reason, when Cepheus is on the west side of the pole, it is between that and Cassio- 
 peia, 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 any imaginary point 
 very near it, is always meant ; and not, as some will vaguely apprehend, a point in thg 
 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.) 
 
 49. There are also two smaller stars about 9 E. of Aldera- 
 ,mn and Alphirk, with which they form a square ; Alderamin 
 being the upper, and Alphirk the lower one on the W. 8 apart. 
 In the centre 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 
 
 48. Number of stars visible? Principal stars? Situation? 49. What other stars, 
 and situation ? Situation of the food, and how known ? Distance of this Asterism from 
 the pole star ? 
 
CEPHEUS. 2? 
 
 *v 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 forme" is 
 338 ; consequently, it is 22 E. of the equinoctial colure. 
 
 The student will understand that right ascension is reckoned on the equinoctial, froai 
 the first point of Aries, E., quite round to the same point again, which is 360. Now, 
 88S* measured from the same point, will reach the same point again, within 22 ; which is 
 the difference between 360 and 33S*. This rule will apply to any other case. 
 
 HISTORY. 
 
 This constellation immortalizes the name of the king of Ethiopia. The name of his 
 queen was Cassiopeia. They were the parents of Andromeda, who was betrothed to 
 Perseus. Cepheus was one of the Argonauts who accompanied Jason on his perilous 
 expedition in quest of the golden fleece. Newton supposes that it was owing to thia 
 circumstance that he was placed in the heavens ; and that not only this, but all the 
 ancient constellations, relate to the Argonautic expedition, or to persons some way con- 
 nected with it. Thus, he observes, that as Musseus, one of the Argonauts, was the first 
 Greek who made a celestial sphere, he would naturally delineate on it thos* 1 figures which 
 had some reference to the expedition. Accordingly, we have on our globes to this day, 
 the Golden Ram, the ensign of the ship in which Phryxus fled to Colchis, the scene o ' 
 the Argonautic achievements. We have also the Bull with brazen hoofs, tamed by 
 Jason ; the Twins, Castor and Pollux, two sailors, with their mother Leda, in the foriii 
 of a. Swan, and Argo, the ship itself; the watchful Dragon, Hydra, with the Cup of 
 Medea, and a raven upon its carcase, as an emolem of death ; also Chiron, the Mastei 
 of Jason, with his Altar and Sacrifice; Hercules, the Argonaut, with his club, his dart. 
 and vulture, with the dragon, crab, and lion which he slew ; and Orpheus, one of the 
 company, with his harp. Ail these, says Newton, refer to the Argonauts. 
 
 Again; we have Orion, the son of Neptune, or, as some say, the grandson of Minos, 
 with his dogs, and hare, and river, and scorpion. We have the story of Perseus in the 
 constellation of that name, as well as in Cassiopeia, Cepheus, Andromeda, and Cetus 
 that of Calisto and her son Areas, in Ursa, Major; that of Icarius, and his daughter 
 Erigone, in Bootes and Virgo. Ursa Minor relates to one of the nurses of Jupiter 
 Auriga, to Erichtonius ; OpMuchus, to Phorbas ; Sagittarius, to Crolus, the son of om 
 of the Muses; Capricorn, to Pan, and Aquarian to Ganymede. We have also Ariadne'* 
 crown, Bellerophon's horse, Neptune's dolphin, Ganymede's eagle, Jupiter's goat, with 
 her kids, the asses of Bacchus, th fixhes of Venus and Cupid, with their parent, the 
 southern fish. These, according to Deltoton, comprise the Grecian constellations men 
 tioned by the poet Aratus; and all relate, as Newton supposes, remotely or immediately 
 to the Argonauts. 
 
 It may be remarked, however, that while none of these figures refer to any transaction? 
 of a later date than the Argonautic expedition, yet the great disagreement which appears 
 in the mythological account of them, proves that their invention must have been o 
 greater antiquity than that event, and that these constellations were received for some 
 time among the Greeks, before their poets referred to them in describing the particular s 
 of that memorable expedition. 
 
 TELESCOPIC OBJECTS. 
 
 1. a CRPHET (Alderamin)- A FINK STAR, with a distant companion on the left shoulder 
 of Cepheus; R. A., 21h. 15m. ; Dec., 61* 54'. It is about half way between Polaris ami 
 Deneb, and 8 south-west from ft Cephei. A 3, white ; B 10, p<*le blue, with a compunioi. 
 of the same magnitude and color. 
 
 2. ft CEPFIKI (Alphirk)A. DOUBLE STAR on the left side of the girdle of Cepheus, two 
 thirds of the distance from Polaris to Alderamin. A 3, white; B 8, blue, with a very 
 minute double star preceding. 
 
 8. y CBPHBF (Er Rai) A DOUBLE STAR in the knee of Cepheus, with a distant telescr/j K 
 companion on the preceding parallel. A 3, yellow; B 14, dusky. R. A., 28h. 82m. 47s 
 Dec., N. 76 44' 7". This star will be the Pole star in about 2360 years. 
 
 HISTORY. Who was Cepl-us ? Why placed in the heavens ? What said of the ongm 
 of other constellations? 
 TKLKSCOPIO OBJECTS. Alpha ? Bc-ta, &c.? What clusters? 
 
 B.Cr, 2 
 
28 ASTRONOMY. 
 
 4. CKPHII (For) in the crown of Cepheus, a fine, though wide DOUBLB STAR; R. A. 22h. 
 28m. 14s. ; Dec., N. 57 35' 9*. A 4}, orange tint ; B 7, fine blue the colors in fine con- 
 trast. This star is -variable, with a period of 5d. Sh. 30m. 
 
 5. A LARGK AND RICH CLUSTER on the left elbow ; R. A., 20h. 2Sm. 17s. ; Dec., N. 60* 06' 
 2". It is 12* due north of a Cygni; and 8" west-south-west of 7? Cephei. "A grand but 
 distant collocation of suns bound together by mutual relations." 
 
 >>. AN IRREGULAR CLUSTER between the head of Cepheus and the chain of Andromeda; 
 R. A., 23h. 17m. 10s.; Dec., N. 60* 43' 1". It is about one-third of the distance- from 
 8 Cassiopese to a Cephei ; and may be seen on Map VI. f near the sceptre of Cephcua 
 For a telescopic view, see Map VIII., Fig. 24. 
 
 CHAPTER II. 
 
 CONSTELLATIONS ON THE MERIDIAN IJ? DECEMBER. 
 
 AEIES (THE RAM). MAP II. 
 
 50. TWENTY-TWO centuries ago, as Hipparchus informs us, 
 this constellation occupied the first sign in the ecliptic, com- 
 mencing at the vernal equinox. But as the constellations gain 
 about 50" on the equinox, at every revolution of the heavens,* 
 they have advanced in the ecliptic nearly 31 beyond it, or more 
 than a whole sign : so that the Fishes now occupy the same 
 place in the Zodiac, that Aries did in the time of Hipparchus ; 
 while the constellation Aries is now in the sign Taurus, Taurus 
 in Gemini, and Gemini in Cancer, and so on. 
 
 ARIES is therefore now the second constellation in the Zodiac. It is situated next east 
 of Pisces, and is midway between the Triangles and the Fly on the N. and the head of 
 Oetus on the S. It contains 66 stars, of which, one is of the 2d, one of the 3d, and two of 
 tiie 4th magnitudes. 
 
 " First, from the east, the Ram conducts the year ; 
 Whom Ptolemy with twice nine stars adorns, 
 Of which two only claim the second rank ; 
 The rest, when Cynthia fills the sign, are lost." 
 
 Aries is readily distinguished by means of two bright stars in the head, about 4* apart, 
 the brightest being the most north-easterly of the two. The first, which is of the 2d 
 magnitude, situated in the right horn, is called Alpha Arietis, or simply Arietix; the 
 other, which is of the 3d magnitude, lying near the left horn, is called Sheratan, and may 
 be known by another star of the 4th magnitude, in the ear, 1 J$ S. of it, called Mesarthim^ 
 which is the first star in this constellation. 
 
 Arietia and Sheratan, are one instance out of many, where stars of more than ordinary 
 brightness are seen together in pairs, as in the Twins, the Little Dog, &c., the brightest 
 Star being commonly on the east. 
 
 * See " Precession of the Equinoxes," page 270. 
 
 t'0. Constellations in this chapter ? Aries 22 centuries ago f Now ; and why t How 
 .lletinguished ? Arietis and Sheratan ? 
 
ARIES. 29 
 
 51. The position of Arietis affords important facilities to 
 nautical science. Difficult to comprehend as it may be, to the 
 unlearned, the skilful navigator who should be lost upon an 
 unknown sea, or in the midst of the Pacific ocean, could, by 
 measuring the distance between Arietis and the Moon, which 
 often passes near it, determine at once not only the spot he was 
 in, but his true course and distance to any known meridian or 
 harbor on the earth. See Part II., page 206. 
 
 Arietis comes to the meridian about 12 minutes after Shera- 
 tan, on the 5th December, near where the sun does in midsum- 
 mer. Arietis, also, is nearly on the same meridian with Almaack, 
 in the foot of Andromeda, 19 N. of it, and culminates only 
 four minutes after it. The other stars in this constellation are 
 quite small, constituting that loose cluster which we see between 
 the Fly on the north, and the head of Cetus on the south. 
 
 When Arietis is on the meridian, Andromeda and Cassiopeia 
 are a little past the meridian, nearly overhead, and Perseus with 
 the head of Medusa, is as far to the east of it. Taurus and 
 Auriga are two or three hours lower down ; Orion appears in 
 the S. E., and the Whale on the meridian, just below Aries, 
 while Pegasus and the Swan are seen half-way over in the west. 
 
 The manner in which the ancients divided the Zodiac into 12 equal parts, was both 
 simple and ingenious. Having no instrument that would measure time exactly, " they 
 took a vessel, with a small hole in the bottom, and having filled it with water, suffered the 
 same to distill, drop by drop, into another vessel set beneath to receive it, beginning at 
 the moment when some 7tar rose, and continuing till it rose the next following night, when 
 it would have performed one complete revolution in the heavens. The water falling down 
 into the receiver they divided into twelve equal parts ; and having twelve other small 
 vessels in readiness, each of them capable of containing one part, they again poured all 
 the water into the upper vessel, and observing the rising of some star in the Zodiac, at 
 the same time suffered the Mjater to drop into one of the small vessels. And as soon as it 
 was full, they removed it, and set an empty one in its place. Just as each vessel was full, 
 they took notice what star of the Zodiac rose at that time, and thus continued the process 
 through the year, until the 12 vessels were filled." 
 
 Thus the Zodiac was divided into 12 equal portions, corresponding to the 12 months of 
 the year, commencing at the vernal equinox. Each of these portions served as the 
 visible representative or xign of the month it appeared in. 
 
 All those stars in the Zodiac which were observed to rise while the first vessel was fill- 
 ing, were constellated and included in the first sign, and called ArieK^ an animal held in 
 great esteem by the shepherds of Chaldea. All those stars in the Zodiac which rose while 
 the second vessel was filling, were constellated and included in the second sign, which, 
 for a similar reason, was denominated Taurux; and all those stars which were observed 
 to rise while the third vessel was filling, were constellated in the third sign, and called 
 Gemini, in allusion to the twin tseaxon of the flocks. 
 
 Thus each sign of 30* in the Zodiac, received a distinctive appellation, according to the 
 fancy or superstition of the inventors ; which names have ever since been retained, 
 although the constellations themselves have since left their nominal signs more than 30 
 behind. The sign Aries, therefore, included all the stars embraced in the first 80 of the 
 Zodiac, and no more. The sign Taurus, in like manner, included all those stars embraced 
 
 fit Position of Arietis? Importance to mariners? When come to meridian ? Where 
 And - i*da and Cassiopeia then ? Perseus ? Taurus, Auriga, Orion, Pegasus and Swan ? 
 What t. other stars in Aries? Ancient method of dividing the Zodiac? Named oi 
 signs If 
 
SO ASTRONOM*. 
 
 In tue next 30* of the Zodiac, or those between 30* and 60% and so of the rest. Of thoe 
 who imagine that the twelve constellations of the Zodiac refer to the twelve tribe* of 
 Israel, some ascribe Aries to the tribe of Simeon, and others, to Gad. 
 
 HISTORY. 
 
 According to fable, this is the ram which bore the golden fleece, and carried Phryxus 
 and his sister Helle through the air, when they fled to Colchis from the persecution of their 
 stepmpther Ino. The rapid motion of the ram in his aerial flight high above the earth, 
 caused the head of Helle to turn with giddiness, and she fell from his back into that part 
 of the sea which was afterwards called Hellespont, in commemoration of the dreadful 
 event. Phryxus arrived safe at Colchis, but was soon murdered by his own father-in-law, 
 35tes, who envied him his golden treasure. This gave rise to the celebrated Argonautic 
 expedition under the command of Jason, for the recovery of the golden fleece. 
 
 Nephele, Queen of Thebes, having provided her children, Phryxus and Helle, with this 
 noble animal, upon which they might elude the wicked designs of those who sought their 
 life, was afterwards changed into a cloud, as a reward for her parental solicitude ; and 
 the Greeks ever after called the clouds by her name. But the most probable account of 
 the origin of this constellation is given in a preceding paragraph, where it is referred to 
 the flocks of the Chaldean shepherds. 
 
 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 temple supposed by some to 
 have been dedicated to Isis, the female deity of the Egyptians, who believed that the ris- 
 ing 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 pertina- 
 ciously 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 
 entered 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 
 10,000 years before. But we may " set to our seal," that whatever is true in fact and cor- 
 rect in inference on this subject will be found, in the end, not 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 tver at rest ; and M. Latroime, 
 a most learned antiquary, has very satisfactorily demonstrated 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 pur- 
 pose 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 horo- 
 scope of the deceased person. 
 
 Of all the discoveries of the antiquary among the relics of ancient Greece, the ruins o* 
 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 tlie hieroglyphics of ancient 
 Egypt, 
 
 The potency of this invaluable discovery has already been signally manifested in set- 
 tling a formidable controversy between the champions of infidelity and those who main- 
 tain the Bible account of the creation. It has been shown that the constellation Pificf^ 
 since the days of Hipparchus, 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 
 *n 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 posi- 
 tion or longitude of any particular star at thai time, it would be easy to fix an unques- 
 tionable date to such a record. Accordingly, when the famous " Egyptian Zodiacs," 
 which were sculptured on the walls of the temple at Dendera, were brought away en 
 *<*., 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. " Educated men 
 f every order, and those- who had the vanity to think themselves such," says the com- 
 inentator of Champollion, " rushed to behold tlw Zodiacs. These Zodiacs were imme- 
 diately published and commented upon, with more or less good faitn and decorum. 
 
 HISTORY. Discovery in Egypt? Use made of the Zodiacs? What did they prove to 
 be. ? How ascertained ? Who most zealous in opposing revelation ? Weans employe-'. 1 
 
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 support. It was 
 unjustifiably taken for granted, that the ruins of Egypt furnished astronomy with monu- 
 ments, containing observations that exhibited the state of the heavens in the most 
 remote periods. Starting with this assumption, a pretence was made of demonstrating 
 by means of calculatlbns received as infallible, 'that the celestial appearances assigned 
 to these monuments extended back from forty-five 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 pro- 
 minent was M. Dupuis, the famous author of L'origine detous left 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 des- 
 tinies of the emperors who made or completed them." 
 
 TELESCOPIC OBJECTS. 
 
 1. a ARIETIS A DOUBLE STAR in the Ram's forehead; R. A. Ih. 5Sm. 10s; Dec. N. 22* 
 42' 02'. A 3, yellow; B 11, purple. 
 
 Two thousand years ago the first meridian or Vernal Equinox passed through th* 
 star- but the recession of the equinox at the slow rate of 50" per year, has, in that lengtl 
 of time, carried the equinoctial nearly 60 to the west, where we now find it. S>*e thi. 
 subject explained in the second part of the book. 
 
 2. /? ARIETIS (Sheratari) A BRIGHT STAR with a distant companion in the coil of the 
 right horn ; R. A. In. 45m. 49s. ; Dec. N. 20' 01' 04'. A 3, pearly white ; B 11, duskv. 
 
 8. y ARIETIS (Mesarthim)* DOUBLE STAR just south of/?; R. A. Ih. 44m. 45s.; Dec. N. 
 18' 30' 05'. A 4}, bright white ; B 5, pale grey. A fine object. Map VIII., Fig. 2. 
 
 4. e ARIETIS A VERT CLOSE DOUBLE STAR near the root of the tail, and between it and 
 Musca; R. A. 2h. 50m. 04s.; Dec. N. 20* 41' 08". A 5, pale yellow; B 6J^, whitish. It 
 requires a good telescope to separate them. 
 
 5. TT ARIETIS A neat TRIPLE STAR in the haunch, about one-third of the distance from 
 ft Arietis to Aldebaran ; R. A. 2h. 40m. 22s. ; Dec. N. 16" 47' 08". A 5, pale yellow ; B 
 8^, flushed ; C 11, dusky. A beautiful trio. 
 
 6. A QUADRUPLE STAR halfway between a and y under the right horn;"R. A. Ih. 50m. 
 43s.; Dec. N. 20 16' 07". A 6, topaz yellow; B 15, deep blue; C 10, lilac; D, pale blue. 
 An exquisite object. 
 
 7. A ROUND NEBULA near y Arietis, and just east of it; R. A. Ih. 50m. 34s.; Dec. N 
 18 13' 06". It is large and pale, and lies among some small stars, some of which form a 
 curve across She south part of the field. 
 
 TRIANGUL^E (THE TRIANGLES). MAP II. 
 
 52. The Triangles are situated between the head of Aries on 
 the north, and the feet of Andromeda on the south. R. A. 
 2h.; Dec. N. 30. They contain two stars of the 4th magni- 
 tude, and two of the 5th ; with several smaller. A line from 
 Sheratan in Aries, to Almaack, will pass through the ludda 
 Trianguli, about midway between them. 
 
 TELESCOPIC OBJECTS? What a Arietis? Other double stars? Triple? Quadruple? 
 Any clusters? Nebulae? 
 62. Situation of the Triangles ? Number and size of stars ? How find their lucida ? 
 
32 ASTRONOMY. 
 
 HISTORY. 
 
 The upper or Northern Triangle is one of the ancient 46 asterisms; and Htvelius took 
 three other stars between it and the head of Aries, to form Triungutum minus. Tha 
 latter figure, however, is discontinued, though shown on the map. 
 
 
 
 TELESCOPIC OBJECTS. 
 
 1 a TRIANGULI A bright FOURTH MAGNITUDE STAR, with a Telescopic companion: R. A. 
 Ih. 43m. 5Ss. ; Dec. N 28* 47' OS". A fc J$, yellow ; B 11, lilac. 
 
 2. TRIANGCLI A MOST DELICATE DOUBLE STAR ; R. A. Ih. 63m. 38s. : Dec. N. 82* 30' 05*. 
 A 5)$, bright yellow ; B 15, dusky. 
 
 3. A large and distin :t but faint PALE WHITE NEBULA, between the Triangles and the 
 head of the Northern Fish ; R. A. Ih. 24m. 51s. ; Dec. N. 29 51* 03". A bright star a 
 little north-west, and five others more remote in the east. 
 
 MUSOA (THE FLY). MAP II. 
 
 53. This very small constellation lies directly between the 
 back of Aries on the south, and the head of Medusa on the 
 north. It has one star of the 2d, two of the 4th, and two of 
 the 5th magnitudes. An unimportant asterism, and not always 
 mentioned in the catalogues, though shown on the map. 
 
 TELESCOPIC OBJECTS. 
 
 1. A FIXE DOUBLE STAR over the back of Aries, nearly midway between the Pleiades ana 
 ft Andromeda ; R. A. 2h. 31m. 20s. ; Dec. N. 26 22' 02". A 6, pale topaz ; B 9, light blue. 
 An easy object. 
 
 2. a MUSCLE a COARSE QUADRUPLE STAR, in the body of the figure, and forming its 
 jucida ; R. A. 2h. 40m. 34s. ; Dec. N. 26 35' 09". A 3, white ; B 18, deep blue ; C 11, lurid; 
 D 9, pale grey. Both these objects are usually classed as belonging to Aries. 
 
 CETUS (THE WHALE). MAP II. 
 
 54. 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 m^an breadth of 20 from N. to S. It is situated below 
 Aries and the Triangles, with a mean declination of 12 S. It 
 ts represented as making its way to the E., with its body below, 
 ind its head elevated above the equinoctial ; and is six weeks in 
 massing the meridian. Its tail comes to the meridian on the 10th 
 of November, and its head leaves it on the 22d of December. 
 
 55. This constellation contains 97 stars ; two of the 2d mag- 
 nitude, ten of the 3d, and nine of the 4th. The head of Cetus 
 
 HISTORY. Which ancient? Who formed the other? Now recognized, or not? 
 
 TELESCOPIC OBJECTS? Double stars? Nebulae? 
 
 53. SitiiHon of Musca? Stars? Relative importance? Is it always recognized ae a 
 constellation ? 54. Cetus? Comparative size? Situation? How represented? 
 bo. Numbei of stars * Magnitudes ? How may the head of Cetius be known ? Brightest 
 
CETUS. 33 
 
 way be readily distinguished, abcnt 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, of 
 the 2d magnitude, in the nose of the Whale. It occupies the 
 S. E. angle of the figure. It is 3^- N. of the equinoctial, and 
 15 E. of El Rischa 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 each about 23 S., 
 and may otherwise be known by a star of the 3d magnitude in 
 the mouth, 3 W. of it, called Gamma, placed in the south mid- 
 dle angle of the pentagon. 
 
 56. Nu is a star of the 4th magnitude, 4 N. W. of Gamma, 
 and these two constitute the S. W. side of the pentagon in the 
 bead of the Whale, and the N. E. side of a similar oblong figure 
 in the neck. 
 
 Three degrees S. S. W. of Gamma, is another star of the 3d 
 magnitude in the lower jaw, marked Delta, constituting the E. 
 side of the oblong pentagon ; and 6 S. W. of this, is a noted 
 star in the neck of the Whale, called Mira, 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 234 days, or about 7 times in 6 years. 
 Herschel makes its period 331 days, 10 hours, and 19 minutes ; 
 while Hevelius assures us that it once disappeared for 4 years ; 
 so that its true period, perhaps, has not been satisfactorily deter- 
 mined. 
 
 The whole number of stars ascertained to be variable amounts to only 15 ; while those 
 which are suspected to be variable, amount to 87. 
 
 57. Mira is 7 S. S. E. of El Rischa, in the bend or knot of 
 the ribbon which connects the Two Fishes. Ten degrees S. of 
 Mira, are 4 small stars, in the breast and paws, about 3 apart, 
 which form a square, the brightest being on the E. Ten degrees 
 S. W. of Mira is a star of the 3d magnitude, in the heart, 
 called Baten Kaitos, which makes a scalene triangle with two 
 other stars of the same magnitude 7 and 10 W. of it ; also, 
 an equilateral triangle with Mira and the easternmost one in 
 the square. 
 
 0tar? Position? Name? 56. Size and Position of Nu? Delta? Mira? Position? 
 Peculiarity? When, and by whom first" noticed ? Period and extent of variability? 
 Whole number of rariable stars? 5T. Baten KcvUos? Position with regard to Mira . 
 r *ther stars ? 
 
34 ASTRONOMY. 
 
 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 maps; but it is better that 
 the student should exercise his own ingenuity in thi's way with reference to the star* 
 themselves, for when 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 exercise iu this way will disclose to the student a 
 surprising multitude of craws, squares, triangles, arc* and letters, by which he will be 
 better able to identify and remember them, than by any instructions that could be given. 
 
 For example : Mira and Baten in the Whale, about 10 apart, make up the S. E. ot 
 shorter side of an irregular square, with El Rischa in the node of the ribbon, and another 
 star in the Whale as far to the right of Baten, as El Rischa is above Mira. 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 t 
 called Diphda. 
 
 In a southerly direction, 25 below Diphda, is Alpha in the head of the Phenix, and 
 about the same distance S. W. is ForaaLhaut, in the mouth of the Southern Fish, forming 
 together a large triangle, with Diphda in t!ie vertex or top of it. 
 
 That fine cluster of small stars S. of ths little square in the Whale, constitutes a part 
 of a new constellation called the ChynvitMl Fumaoe. The two stars N. E., and the 
 three to the southward of the little square, are in the river Eridwn/us, 
 
 HISTORY. 
 
 This constellation is of very early antiquity: though most writers consider it the 
 famous sea-monster sent by Neptune to devour Andromeda because her mother Cassio- 
 peia had boasted herself fairer than Juno or the Sea Nymphs ; but slain by Perseus ana 
 placed among the stars in honor of his achievement. 
 
 " The winged hero now descends, now soars, 
 And at his pleasure the vast monster gores. 
 Deep in his back, swift stooping from above, 
 His crooked sabre to the hilt he drove." 
 
 It is quite certain, however, that this constellation had a place in the heavens long 
 prior to the time of Perseus. When the equinoctial sun in Aries, which is right over the 
 head of Cetus, opened the year, it was denominated the Preserver, or Deliverer, by the 
 idolaters of the East. On this account, according to Pausanius, the sun was worshipped, 
 at Eleusis, under the name of the Preserver or Saoiwtr. 
 
 " With gills pulmonic breathes the enormous whale, 
 And spouts aquatic columns to the gale ; 
 Sports on the shining wave at noontide hours, 
 And shifting rainbows crest the rising showers." Darwin. 
 
 TELESCOPIC OBJECTS. 
 
 1. /? CETI A DOUBLE STAR ; R. A. Oh. 35m. 84s. ; Dec. S. 18 51' 9". A 2%, yellow ; B 12, 
 pale blue. 
 
 2. y CETI A CLOSE DOUBLE STAR in the Whale's mouth ; R. A. 2h. 85m. Ols. ; Dec. N. 
 2" 83' 5". A 3, pale yellow ; B 7, lucid blue ; the colors finely contrasted. 
 
 3. v A DOUBLE STAR in the Whale's eye ; y R. A. 2h. 27m. 29s. ; Dec. N. 4* 53' 5'. A 4J$, 
 pale yellow ; B 15, blue. 
 
 4. ALONG NARROW NEBULA, of a pale, milky tint; R. A. Oh. 39m. 45s.; Dec. S. 26* 
 10' 1". It is situated in the space south of the tail of Cetus, near a line drawn from 
 a Andromeda to /3 Ceti. Discovered by Miss Herschel, in 1783. 
 
 5. A PLANETARY NEBULA; R. A. 2h. 19m. 25s.; Dec. S. 1 51' 6'; in the middle of the 
 Whale's neck. 
 
 6. A BRIGHT ROUND NEBULA ; R. A. lh. 23m. 20s. ; Dec. S. 7 41' 8*. Registered ly Sir 
 W. Herschel, 1785. It is just above the Whale's back. 
 
 HISTORY. Antiquity? Its original name ? When, and why? What worship in son- 
 lequence ? 
 
 OBJECTS. Beta? Gamma? Nu? Nebulae? 
 
PERSEUS, ET CAPUT MEDUSAE. 35 
 
 T. A ROTTND STELLAR NEBCT.A, near d in the Whale's lower jaw, and about 2%* from y, 
 on a line towards , or south by west. A very distant object, classed by Sir W. Herschel, 
 as 910 times as distant as stars of the first magnitude. 
 
 PERSEUS, ET CAPUT MEDUSA. MAP III. A]S T D IY. 
 
 58. PERSEUS is represented with a sword in his right hand, 
 the head of Medusa in his left, and wings at his feet. It is 
 situated directly N. of the Pleiades and the Fly, between 
 Andromeda on the W. and Auriga on the E. Its mean decli- 
 nation is 46 N. It is on the meridian the 24th of December. 
 It contains, including the head of Medusa, 59 stars, two of 
 which are of the 2d magnitude, and four of the 3d. According 
 to Eudosia, it contains, including the head of Medusa, 67 stars. 
 
 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 aixty-itt^Den ; and two of these he boasts, 
 Nobly refulgent in the second rank 
 One in his vest, one in Medusa's head." 
 
 59. THE HEAD OF MEDUSA is not a separate constellation, 
 out forms a part of Perseus. It is represented as the trunkless 
 head of a frightful 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 ; three of the 
 4th magnitude, and one, varying alternately from the 2d to the 
 4th magnitude. This remarkable star is called Algol. It is 
 situated 12 E. of Almaack, in the foot 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 
 magnitude in about 3 hours, and back again in the same time ; 
 after which it remains steadily brilliant for 2f days, when the 
 iame changes recur. 
 
 The periodical variation of Algol was determined in 1783, by John Goodricke, of York 
 (Eng.), to be 2 days, 20 hours, 43 minutes, and 56 seconds. Dr. Herschel attributes th 
 variable appearance of Algol to spots upon its surface, and thinks it has a motion on its 
 axis sinrlar to that of the #un. He also observes, of variable stars generally: "The 
 rotary motion of the stars upon their axis 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 proved as the diurnal motion of the earth. Dark spots, 
 
 58. Perseus? How represented? When on the meridian? Number of stars? Size? 
 59. Head of Medusa? How represented? Number of stars? What remarkable cie? 
 Situation? Variableness and period? When and by whom determined? Supposed 
 cause of variability ? Lalando ? 
 
 2* 
 
36 ASTRONOMY. 
 
 or larpe portions of the surface less luminous than the rest, turned alternately In certain 
 directions either toward, or from us, will account for all the phenomena of periodical 
 changes in the lustre 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 fr 
 remain whole nights, in his old age, upon the Pont Jfeuf, to exhibit to the curious the 
 Variations in the brilliancy of the star Algol. 
 
 60. Nine degrees E. by N. from Algol, is the bright star Alge- 
 nib, of the 2d magnitude, in the side of Perseus, which with Al- 
 maack, makes a perfect right angle at Algol, with the open part 
 towards Cassiopeia. By means of this strikingly perfect figure, 
 the three stars last mentioned may always be recognized 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 December, 15 minutes after Algol, at which 
 time the latter is almost directly overhead. When these two 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 heavens 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." 
 
 61. The Milky Way around Perseus is very vivid, being undoubt- 
 edly a rich stratum of fixed stars, presenting the most wondei - 
 ful and sublime phenomenon of the Creator's power and great- 
 ness. Kohler, the astronomer, observed a beautiful nebula near 
 the face of Perseus, besides eight other nebulous clusters in dif- 
 ferent parts of the constellation. 
 
 The head and sword of Perseus are exhibited on the circumpolar map. That very 
 bright star 23* E. of Algol, is Capella in the Charioteer. 
 
 HISTORY 
 
 Perseus was the son of Jupiter and Danae. He was no sooner born than he was cast 
 Into the sea, with his mother ; but being driven on the coasts of one of the islands of the 
 Cyclades, they were rescued by a fisherman, and carried to Polydectes, the king of the 
 place, who treated them with great humanity, and intrusted them to the care of the 
 priests of Minerva's temple. His rising genius and manly courage soon made him a 
 favorite of the gods. At a great feast of Polydectes, all the nobles were expected to 
 present the king with a superb and beautiful horse ; but Perseus, who owed his benefac- 
 tor much not wishing to be thought less munificent than the rest, engaged to bring him 
 the head of Medusa, the only one of the three Gorgons, who was subject to mortality. 
 The names of the other two were Stheno and Euryale. They were represented with ser- 
 pents wreathing round their heads instead of hair, having yellow wings and brazen 
 hands ; their bodies which grew indissolubly together, were covered with impenetrable 
 ecales, and their very looks had the power of turning into stones all those on whom 
 they fixed their eyes. 
 
 To equip Perseus for this perilous enterprise, Pluto, the god of the infernal regions, 
 fent him his helmet, which had the power of rendering the wearer invisible. Minerva, 
 the goddess of wisdom, furnished him with her buckler, which was as resplendent as a 
 polished mirror ; and he received from Mercury wings for his feet, and a dagger made 
 
 60. Algenib? How known? When on the meridian? Where, then, are the PI siades? 
 What the general aspect of the heavens? 61. Milky Way around Perseus? Observa 
 lion of Kohler? 
 
 . Wno was Perseus? What fate at birth, &c.f 
 
PERSEUS, ET CAPUT MEDUSAE. 3*5 
 
 af dIav***Jk Thus equipped, he mounted into the air, conducted by Mir erva, and came 
 upon tl.c n.iAisters who, with the watchful snakes about their heads, were all asleep. He 
 approached thorn, and with a courage which amazed and delighted Minerva, cut off with 
 one blow Medusa's head. The noise awoke the two immortal sisters, but Pluto's helmet 
 rendered Perseus invisible, and the vengeful pursuit of the Gorgons proved fruitless. 
 " In the mirror of his polished shield 
 Reflected, saw Medusa slumbers take, 
 And not one serpent by good chance awake ; 
 Then backward an unerring blow he sped, 
 And from her body lopped at once her head." 
 
 Perseus then made his way through the air, with Medusa's head yet reeking in his> 
 band, and from the blood which dropped from it as he flew, sprang all those innumerable 
 serpents that have ever since infested the sandy deserts of Libya. 
 " The victor Perseus, with the Gorgon head, 
 O'er Libyan sands his airy journey sped, 
 The gory drops distilled, as swift he flew, 
 And from each drop envenomed serpents grew." 
 
 The destruction of Medusa rendered the name of Perseus immortal, and he waa 
 changed into a constellation at his death, and placed among the stars, with the head of 
 Medusa by his side. 
 
 TELESCOPIC OBJECTS. 
 
 1. a PERSEI A FINE DOUBLE STAR ; R. A. 3h. 12m. 55s. ; Dec. N. 49 IT 2". A 2j, bril- 
 liant lilac ; B 9, cinereous. This is Algenib, in the hero's left side. 
 
 2. ft PERSEI, or Algol; R. A. 2h. 57m. 46s. ; Dec. N. 41* 20*. A variable DOUBLE STAR. 
 A 2 to 4, whitish ; B 11, purple. The former varies in brightness periodically, from the 
 2d to the 4th magnitude, and back again to the 2d magnitude, period being 2d. 20h.48m. 
 56s. ; an object of great interest. 
 
 3. y PERSEI A WIDE UNEQUAL DOUBLE STAR in the hero's left shoulder: R. A. 2h. 53m. 
 14s. ; Dec. N. 52* 52' 4'. A 4, flushed white ; B 14, clear blue. 
 
 4. 6 PERSEI A BRIGHT STAR with a companion in the hero's hip; R. A., 3h. 31m. 33s.; 
 Dec., N. 47* 16' 2". About 3" south-west of a Persei. A 3%, white ; B 11, pale blue. 
 
 5. f PERSEI A NEAT DOUBLE STAR in the right knee ; R. A. 8h. 47m. 08s. ; Dec. N. 89* 
 82' 4". A 3^, pale white ; B 9, lilac ; a fine delicate object. 
 
 6. PERSEI A DELICATB QUADRUPLE STAR ; R. A. 3h. 44m. 05s. ; Dec. N. 81* 24' 2". 
 A 3%, flushed white; B 10, smalt blue; C 12, ash-colored ; D 11, blue. It is situated in 
 the right foot, and is designated by Smyth as " an elegant group." 
 
 7. 7? PERSEI-A FINK DOUBLE STAR in the head of the figure ; R. A. 2h. 39m. 04s. ; Dec. 
 N. 55" 13' 5". A 5, orange ; B 8Jg, smalt blue ; the colors in fine contrast. 
 
 8. A GORGEOUS CLUSTER in the sword handle of Perseus ; R. A. 2h. 08m. 58s. ; Dec. N. 
 56 24' 4". It may be seen with the naked eye, and when seen through a good telescope, 
 is one of the most magnificent objects in the heavens. Map VIII., Fig. 25. 
 
 9. An EXTENSIVE AND RICH CLUSTER on the right side of Perseus, in a rich portion of 
 the galaxy. R. A. 8h. 04m. Ols.; Dec. N. 46' 87' 9". Smyth says "it has a gathering 
 epot about 4' in diameter, where the star-dust glows among minute points of light." 
 Herschel says, " the large stars are arranged in lines like interwoven letters. 
 
 10. An ELONGATED NEBULA ; R. A. 2h. 30m. 25s.; Deo. N. 38' 21' 3" ; supposed to be a 
 vast ring, seen obliquely. Map VIII., Fig. 26. 
 
 11. A pretty compressed OVAL GROUP OF STARS, in the left knee of Perseus, nearly mi J- 
 iray between A and //; R. A. 3h. 58m. 11s.; Dec. N. 49* 04' 05". A well-marked object, 
 surrounded by a curve of larger stars, somewhat in the form of the letter D. Map VIII., 
 Fig. 27. 
 
 TELESCOPIC OBJECTS. Alpha ? Beta? Gamma? Delta? Epsilon? Zeta? Eta? 
 Clusters ? Nebula? Which shown on the map? 
 
<9 ASTRONOMY. 
 
 CHAPTER III. 
 
 CONSTELLATIONS ON THE MERIDIAN IN JANUARY. 
 
 TAURUS (THE BULL). MAP III. 
 
 62. TAURUS is represented in an attitude of rage, as if about 
 to plunge at Orion, who seems to invite the onset by provoca^ 
 tions of assault and defiance. Only the head and shoulders of 
 the animal are to be seen ; but these are so distinctly marked 
 that they caimot be mistaken. 
 
 The constellations which pass our meridian in the months of January, February and 
 March, present to us the most brilliant and interesting portion of the heavens ; embrac- 
 ing an annual number of stars of the highest order and brightness, all so conspicuously 
 situated, that the most inexperienced can easily trace them out. 
 
 63. Taurus is now the second 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 succeeded 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 N. 
 
 64. Taurus contains 141 visible stars, including two remark- 
 able clusters called the PLEIADES and HYADES. The first is now 
 on the shoulder, and the latter in the face of the Bull. The 
 names of the Pleiades are Alcione, 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 
 8aw 78 stars; and Rheita affirms that he counted 200 stars in 
 this small cluster. For its appearance through an ordinary tele- 
 scope, see Map VIII., Fig. 28. 
 
 The most ancient authors, such as Homer, Attains, and Geminus, counted only *?'ca 
 Pleiades; but Simonides, Varro, Pliny, Aratus, Hipparchus, and Ptolemy, reckon them 
 
 62. How is Taurus represented ? How much of him seen? What constellations most 
 brilliant? J68. In what sign is Taurus ? What constellation ? How 4000 years ago? 
 What next led the year? What now? At what time does Taurus set with the sun? 
 Row situated? 64. How many visible stars in Taurus? Clusters? How situated? 
 Names of the Pleiades? What said of Merope? How many of the Pleiades visibl* to 
 the naked eye? Dr. Hook and Rheita? Ancient authors? 
 
TAURUS. .<9 
 
 leven in number; and it was asserted, that the seventh had been seen before the burn- 
 ing of Troy ; but this difference might arise from the difference in distinguishing them 
 with the naked eye. 
 
 65. The Pleiades are so called from the Greek word, rrXeeiv 
 pkein, to sail; because at this season of the year, they were 
 considered "the star of the ocean" to the benighted mariner. 
 
 Yirgil who flourished 1200 years before the invention of the magnetic needle, says 
 that the stars were relied upon, in the first ages of nautical enterprise, to guide the rude 
 bark over the seas. 
 
 "Tune alnos primum fluvii sensere cavatas ; 
 Navita turn stellis numeros, et nomina fecit, 
 Pleiadas, Hyadas, claramque Lycaonis Arcton." 
 " Then first on seas the shallow alder swam ; 
 Then sailors quarter'd heaven, and found a name 
 For every fix'd and every wand'ring star 
 The Pleiades, Hyades, and the Northern Car." 
 
 The same poet also ,. escribes Palinurus, the renowned pilot of the Trojan fleet, as 
 watching the face of the nocturnal heavens. 
 
 "Sidera cuncta notat tacito labentia ccelo, 
 Arcturum, pluviasque Hyadas, geminosque Triones, 
 Armatumque auro circumspicit Orioua." 
 * Observe the stars, and notes their sliding course, 
 Ihe Pleiades, Hyades, and their wat'ry force; 
 And both the Bears is careful to behold, 
 And bright Orion, arm'd with burnished gold." 
 
 Indeed, this sagacious pilot was once so intent in gazing upon the stars while at the 
 helm, that he fell overboard, and was lost to his companions. 
 
 " Headlong he fell, and struggling in the main, 
 Cried out for helping hands, but cried in vain." 
 
 66. Alcyone, of the 3d magnitude, 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 even- 
 ing of the 1st of January, and may serve in place of the sun, to 
 indicate the time, and as a guide to the surrounding stars. 
 
 According to Hesiod, who wrote about 900 years before the birth of our Savior, thf 
 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-illumined 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 cosmical 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 p)-esent, 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 pre- 
 cession (50ii"), will give 2465 years since the time of Thales. Thus does astronomy 
 become the parent of chronology. 
 
 65. Why Pleiades so called? Remark, and quotations from Virgil? 66. What said 
 of Alcyone ? Of the ^t.her five ? When on the meridian ? Serve what purpose ? Period, 
 and remark of Hesiod? Of Pliny? What calculation respecting the pasiage of tbft 
 Ple;a<lc ^ver the meridian ? 
 
40 ASTRONOMY. 
 
 If it be borne in mind that the stars uniformly rise, come to the meridian, and set abont 
 four minutes earlier every succeeding night, it will be 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 example : at what time will the seven stars culminate on the 5th 
 of January ? Multiply the 5 days by 4, and take the result from the time they culminate 
 en the 1st, and it will give 30 minutes after 8 o'clock in the evening. 
 
 67. The Pleiades are also sometimes called Vergilia, or th 
 " Virgins of Spring " because the sun enters this cluster in the 
 " season of blossoms/ 7 about the 18th or 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 38 : 31.) 
 
 The Syrian name of the Pleiades is Succotk, or Succoth-Benoth, derived from a Chai- 
 daic word, which signifies " to speculate, to observe," and the " Men of Succ^th" 
 (2 Kings 17 : 30) have been thence considered observers of the stars. 
 
 68. The Hyades are situated 11 S. E. of the Pleiades, in the 
 face of the Bull, and may be readily distinguished by means of 
 five stars so placed as to form the letter Y. (Map YIIL, Fig. 
 29.) The most brilliant star is on the left, in the top of the 
 letter, and called Aldebaran ; from which the moon's distance is 
 computed. 
 
 " A star of the first magnitude illumes 
 His radiant head ; and of th second rank, 
 Another beams not far remote." 
 
 The ancient Greeks counted seven in this cluster : 
 
 " The Bull's head shines with seven refulgent flames, 
 Which, Grecia, Hyades, from their ^lowering names." 
 
 69. 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 
 Btar led up the starry host from the vernal equinox. It comes 
 to the meridian at 9 o'clock on the 10th of January, or 48-| 
 minutes after Alcyone, on the 1st. When Aries is about 27 
 high, Aldebaran is just rising to 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 Beta or El Nath ; (this star is also in the 
 foot of Auriga, and is common to both constellations.) From Beta in the northern horn, 
 to Zeta, in the tip of the southern horn, it is 8% in a southerly direction. This star 
 forms a right angle with Aldebaran and Beta. Beta and Zeta, then, 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 Beta, is Capetta, in the constellation Auriga, 
 
 G7. What other name have the Pleiades, and why ? Citation from Job ? Syrian name ? 
 68. Where are the Hyades situated? How known? Where the most brilliant star? 
 Name ? Are they shown on the map ? 69. Origin and import of the name Aldebaran f 
 When does it come to the meridian at 9 o'clock p.m. ? Where is Beta? In wi.at other 
 constellation ? Zeta, and its distance? How situated wilh reference to AKibarar anJ 
 Beta? How Beta and Zeia ? Capeua? 
 
ORION. 41 
 
 HISTORY. 
 
 According to the Grecian mythology, this is ibz animal which bore Europa over th 
 eas to that country which derived from her its name. She was the daughter of Ageaor 
 and princess of Phrenicia. She was so beautiful that Jupiter became enamoured of her 
 and assuming the shape of a snow-white bull, he mingled with the herds of Agenor, 
 while Europa, with her female attendants, were gathering flowers in the meadows. 
 Europa care-'sed the beautiful animal, and at last had the courage to sit upon his back. 
 The god now took advantage of her situation, and with precipitate steps retired towards 
 the shore, and crossed the sea with Europa upon his back, and arrived safe in Crete. 
 Some suppose she lived about 1552 years before the Christian Era. It is probable, however, 
 that this constellation had a place in the Zodiac before the Greeks began to cultivate a 
 knowledge of the stars ; and that it was rather an invention of the Egyptians or Chal- 
 deans. Both the Egyptians and Persians worshipped a deity under this figure, by the 
 name of Apis ; and Belzoni is said to have found an embalmed bull in one of the notable 
 sepulchres near Thebes. 
 
 In the Hebrew Zodiac, Taurus is ascribed to Joseph. 
 
 The Pleiades, according to fable, were the seven daughters of Atlas and the nympn 
 Pleione, who were turned into stars, with their sisters the Hyades, on account of their 
 ftmiable virtues and mutual affection. 
 
 Thus we everywhere find that the ancients, with all their barbarism and idolatrj, 
 entertained the belief that unblemished virtue and a meritorious 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, m 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 orna- 
 ments in the Christian Church, and models of social virtue. 
 
 TELESCOPIC OBJECTS. 
 
 1. a TACRI (Aldebarari) A star of the first magnitude with a telescopic companion 
 R. A. 4h. 26m. 44s. ; Dec. N. 16 10' 9". A 1, pale rose tint ; B 12, sky blue. 
 
 2. @T\URi(El Nath)R. A. 5h. 16m. 11s.; Dec. N. 28 28'. A fine star, with a 
 distant companion. A 2, brilliant white ; B 10, pale grey. 
 
 8. y TAURI One of the Hyades ; R. A. 4h. 10m. 41s. ; Dec. 11* 14' 1". A bright star, 
 with a distant telescopic companion ; A 3J, yellow ; B 11, pale blue. 
 
 4. 77 TAURI (Alcyone) One of the Pleiades; R. A. 3h. 37m. 57s.; Dec. N. 23* 36' 3'. 
 A 3, greenish yellow ; B, pale white and distant. 
 
 5. A NEBULOUS STAR; R. A. 8h. 59m. 06*. ; Dec. N. 30* 20' 5'. A star of the eighth 
 magnitude, with a faint luminous atmosphere surrounding it, and about 3' in diameter. 
 This star and nebula led Sir William Herschel to adopt his Nebula Theory, or theory of 
 condensation of gas or nebulous matter, into suns and worlds. 
 
 6. A LARGE NEBULA ; R. A. 5h. 24m. 51s. ; Dec. N. 21 54' 2'. It is about one degree 
 tiorth-west of in the tip of the Bull's southern horn. It is an oval form, with several 
 minute telescopic stars in its vicinity. For drawing, see Map VIII., .Fig 30. 
 
 Of the Pleiades and Ilyades, two prominent clusters, we have spoken at 64, 65. 
 
 . MAP III. 1 
 
 70. Whoever looks up to this constellation and learns its 
 aame, will never forget it. It is too beautifully splendid to need 
 a description. When it is on the meridian, there is then above 
 
 H'STORY. Story of Europa and Jupiter? What probability? What said of the 
 Egyptians and Persians? Hebrew zodiacs? Fabulous paternity of the Pleiades? Why 
 iurned into stars? W T hat remarks respecting the ancients? 
 
 TELESCOPIC OBJKCTS. Alpha? Beta? Gamma? Eta? Nebulae? Point out on the 
 map. 
 
 70. What Is said of Orion? Of the view when on the meridian? How is Cnon repr*. 
 
42 ASTRONOMY. 
 
 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 represented on celestial maps 
 by the figure of a man in the attitude of assaulting the 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, hnmers'd in boundless spheres, 
 Three stars, less bright, but yet as great, he bears, 
 But farther off removed, their splendor's lost ; 
 Thus graced and arm'd he leads the starry host." 
 
 71. The centre of the constellation is midway between the 
 poles of the heavens and directly over the equator. It is also 
 about 8 W. of the solstitial colure, and comes to the meridian 
 about the 23d of January. The whole number of visible stars 
 in this constellation is 78 ; of which, two are of the first magni- 
 tude, four of the 2d, three of the 3d, and fifteen of the 4th. 
 
 72. 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 
 outlines 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 is a star of the 2d magnitude 
 on the W. shoulder ; Betelguese is a star of the 1st magnitude, 
 7| E. of Bellatrix, o-i the E. shoulder. It is brighter than 
 Bellatrix, and lies a little farther toward the north ; and comes 
 to the meridian 30 minutes after it, on the 21st of January. 
 These two form the upper end of the parallelogram. 
 
 73. Rigd is a splended star of the 1st magnitude, in the left 
 foot, on the W. and 15 S. of Bellatrix. 8aiph is a star of the 
 3d magnitude, in the right knee, 8 E. of Rigel. These two 
 form the lower end of the parallelogram. 
 
 uented on the maps: ? How described by Manilius ? 71. Situation of Orion? Number 
 of visible stars ? Magnitudes? 72. What is the Ell and Yard? What constitutes the 
 outline of Orion? Where is BeUatrixt ctelguee and magnitude? 73. Rigel\ 
 Haipht 
 
ORION. 43 
 
 " 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." 
 
 74. 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 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, because there are 
 DO 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 husband- 
 men called them Jacob's rod, and sometimes 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 recommended to apply this rule. 
 
 It is necessary that the scholar should task his ingenuity only a few evenings in apply- 
 ing such a standard to the stars, before he will learn to judge of their relative distance* 
 with an accuracy that will seldom vary a degree from the truth. 
 
 75. The northernmost star in the belt, called Mintika, is less 
 than y 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 magnitudes, S. of the belt, running down 
 obliquely towards Saiph, which forms the sword. This row is 
 also called the Ell because it is once and a quarter the length 
 of the Yard or belt. 
 
 74. What constitutes the head of Orion? What in the middle of the parallelogram f 
 Names, and why? "Three stars?" "Three Kings?" "Bands of Orion," "Jacob's 
 Rod," Napoleon," " Ell and Yard ? Use of the Ell and Yard ? 75. What said of Mivt, 
 tikat Of the "three stars?" What other row of stars ? Forms what? Called wb*t 
 and why ? 
 
44 ASTRONOMY. 
 
 T6. About 9 W. of Bellatrix, are eight stars, chiefly of the 
 4th magnitude, in a curved line running N. and S. with the con- 
 cavity toward Orion ; these point out the skin of the lion in 
 his left hand. Of Orion, on the whole, we may remark witb 
 Eudosia: 
 
 " He who admires not, to the stars is blind." 
 
 HISTORY. 
 
 According to some authorities, Orion was the son of Neptune and queen Euryale, a 
 famous Amazonian huntress, and possessing the disposition of his mother, he became 
 the greatest hunter in the world, and even boasted that there was not an animal on 
 ea.-th which he could not conquer. To punish this vanity, it is said that a scorpion 
 sprung up out of the earth and bit his foot, that he died ; and that at the request of 
 Diana he was placed among the stars directly opposite to the Scorpion that caused his 
 death. Others say that Orion had no mother, but was the gift of the gods, Jupiter, 
 Neptune, and Mercury, to a peasant of Bceotia, as a reward of piety, and that he was 
 invested with the power of walking over the sea without wetting his feet. In strength 
 and stature he surpassed all other mortals. He was skilled in the working of iron, from 
 which he fabricated a subterranean palace for Vulcan ; he also walled in the coasts of 
 Sicily against the inundations of the sea, and built thereon a temple to its gods. 
 
 Orion was betrothed to the daughter of (Enopion, but he, unwilling to, give up his 
 daughter, contrived to intoxicate the illustrious hero and put out his eyes, on the sea- 
 shore where he had laid himself down to sleep. Orion, finding himself blind when he 
 awoke, was conducted by the sound to a neighboring forge, where he placed one of the 
 workmen on his back, and, by his directions, went to a place where the rising sun was 
 seen with the greatest advantage. Here he turned his face toward the luminary, and, 
 as it is reported, immediately recovered his sight, and hastened to punish the perfidioiu 
 cruelty of CEnopion. 
 
 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 extremely terrible to mariners, in the early advtm- 
 tures 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, charged with deluges of rain, 
 Orion rages on the wintry main." 
 
 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 omni- 
 science 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 awful majesty who " com- 
 mandeth the sun and sealeth up the stare ; who alone spreadeth out the heavens, and 
 maketh Arcturus, Orion, and Pleiades, and the chambers of the south:" and in anothe- 
 {ilace, the Almighty demands of him " Knowest thou the ordinances of heaven? 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?" 
 
 Calmet supposes that Mazzaroth is here put for the whole order of celestial bodies Jr 
 the Zodiac, which, by their appointed revolutions, produce the various seasons of th< 
 year, and the regular succession of day and night. Arcturus is the name of the prin- 
 cipal 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 sterns to be 
 pursuing the Great Bear around the North pole. 
 
 76. What star? mentioned west of Bellatrix? Remark respecting Orion? 
 
 HISTORY. Story of parentage? Disposition and boasting? Punishment? Wha( 
 ether account? What mention of by Virgil? By Job and Homer? Supposition of 
 Calmet? Wha' meant by "Arcturus and his sons?" 
 
LEPU8. 45 
 
 TELESCOPIC OBJECTS. 
 
 1. a ORIONIS (Betdguese)^.. A. 5h. 46m. 80s. ; Dec. N. 7* 22' 3*. A 1, orange tint; 
 B 11, bluish. 
 
 2. /3 ORIONIS (RigeD R. A. 5h. 6m. 51s ; Dec. S. 8 23' 5'. A 1, pale yellow; B 9, 
 sapphire blue. Map VIII. Fig. 3. 
 
 3. y OKIONIS (JBellatrix)l{. A. 5h. 16m. 33s. ; Dec. N. 6 12'. A FINK STAR, with a 
 minute d'stant companion. A 2, pale yellow ; 13 15, grey. 
 
 4. 6 ORIOXIS (Mintafai) A coarse DOUBLE STAR in the girdle of the figure; R. A. 5h 
 23ru. 50s. ; Dec. S. 25' 4". A 2, white ; B 7, pale violet. 
 
 5. e ORIONIS (Alnilam) in the centre of his belt ; R. A. 5h. 28m. 06s. ; Dec. S. 1* 18' C* 
 A 2^, white and nebulous; B. 10, pale blue. 
 
 6. C OKIONIS (Alnitali) the last or lowest in the belt; R. A. 5h.82m. 41s.; Dec. 3. 2 O^. 
 A fine TRIPLE STAR. A 3, topaz yellow ; B 6}, light purple ; and C 10, gray. 
 
 7. A minute DOUBLE STAR and cluster, in Orion's left hand; R. A. 5h. 59m. 25s. ; Dec. 
 N. 13 58' 6\ A 7>$, B 8}$, both lucid white. 
 
 8. Another DOCBLE STAR in a cluster, in the left shoulder; R. A. 6h. 03m. 35s. ; Dec. N. 
 5* 28' 9". A 9)6 and B 10, both pale yellow. A tolerably rich cluster, with numerous 
 stragglers. 
 
 9. A PLANKTAT NEBULA, of a bluish white tint, on the nape of Orion's neck small, pale, 
 but quite distinct. R. A. 5h. 33m. 21s. ; Dec. N. 9 00' 2". 
 
 10. Two stars " in a WISPY NEBULA," just above the left hip; R. A. 5h. 3Sm. 33s.; Dec. 
 N. 00' 7". A 8^ and B. 9, both white. A singular mass, between two small stars, about 
 equi-distant, in a blankish part of the heavens. 
 
 11. The GREAT NEBULA OF ORION The most conspicuous nebula in all the heavens. It 
 is situated in the bword of Orion, below the middle star of the belt ; R. A. 5h. 27m. 25s.; 
 Dec. S. 5 30'. For its position in the constellation see Map VIII., Fig. 31. It maj- be 
 seen with a common telescope. There is an apparent opening in one side of this nebula, 
 through which, as through a window, we seetu to get a glimpse of other heavens, and 
 brighter regions. (Map VIII., Fig. 82.) 
 
 12. The middle star in the sword is in the midst of this nebula, and with powerful tele- 
 scopes is found to be sextuple. The writer has often seen the fifth star with a 6-inch 
 refractor. These stars constitute the Trapezium of Orion. The region around this 
 nebula is rich in stars, as shown on Map Vill., Fig. 33. 
 
 LEPUS (THE HAKE). MAP III. 
 
 77. This constellation is situated directly south of Orion, and 
 comes to the meridian at the same time ; namely, on the 24th 
 of January. It has a mean declination 18 S., and contains 19 
 fciuull stars, of which, the four principal ones are of the 3d magni- 
 tude. It may be readily distinguished by means of four stars 
 of the 3d magnitude, in the form of an irregular square, or 
 trapezium. 
 
 78. Zeto, of the 4th magnitude, is the first star, and is 
 situated in the back, 5 S of Saiph*, in Orion. About the same 
 distance below Zeta are the four principal stars, in the legs and 
 feet. These form the square. They are marked Alpha, Beta, 
 Gamma,, Delta. 
 
 TELESCOPIC OBJECTS. Alpha ? Beta? Gamma? Delta, &c.l What double BtaisT 
 Nebula? ? Point out on the map ? 
 
 77. Location of Lepus? Number and magnitude of stars? How may it be distiu- 
 puished? 78. Size and situation of Zeta? Other principal stars? How marked oa 
 the map f 
 
46 ASTRONOiMY. 
 
 f. 
 
 79. Alpha, otherwise called Arneb, and Beta form the N. W. 
 end of the trapezium, and are about 3 apart. Gamma and 
 Delta form the S. E. end, and are about 2 apart. The upper 
 right-hand one, which is Arneb, is the brightest of the four, and 
 is near the centre of the constellation. Four or five degrees S. 
 of Iligel are four very minute stars, in the ears of the Hare. 
 
 HISTORY. 
 
 This constellation is situated about 18 west of the Great Dog, which, from the motion 
 of tin earth, seetr.s to be pursuing it, as the Greyhounds do the Bear, round the Circuit 
 of the skies It was one of those animals which Orion is said to have delighted in hunt- 
 ing, and which, tor this reason, was made into a constellation and placed near hire 
 among the stars. 
 
 TELESCOPIC OBJECTS. 
 
 1. a LKPORIS (Arneb') A distant DOUBLE STAR ; R. A. 5h. 25m. 40s. ; Dec. S. 17 56' 05*. 
 A 33$, pale yellow ; B 9>, grey. 
 
 2. $ LKPORIS (Nihal) A STAR with a distant telescopic companion ; R. A. 5h. 21m. 23s. ; 
 Dec. S. 20' W 05". A 4, deep yellow; B 11, blue. 
 
 3. y LKPOH.& A wide TRIPLE STAR in a barren field; R. A. 5h. 3Tm. 48s.; Dec. S. 22" 
 80' 0'2'. .A *, light yellow ; B 6^, pale green ; C 13, dusky. 
 
 4. L LEPORIS A delicate DOCBLK STAR in the Hare's left ear ; R. A. 5h. 04m. 50s. ; Dec. 
 S. 12* 03' 09". A 4%, white ; B 12, pale violet, with a reddish distant star nearly north. 
 
 5. K LEPORIS A close DOUBLE STAR, at the root oilhe left ear; R. A. 5h. 5in. 51s. ; Dec. 
 B. 13" 08'. A 5, pale white ; B 9, clear grey. 
 
 6. A bright STELLAR NEBCLA, under the Hare's feet; R. A. 5h. 17m. 50s. ; Dec. S. 24* 39' 
 09". A fine object of a milky white tinge, and blazing towards the centre. Hersche^ 
 describes it as " a beautiful cluster of stars, nearly 3' in diameter, of a globular forn\ 
 and extremly rich." An imaginary Jine run from Betelguese before a Leporis, and o/etf 
 S, will hit this object about 4 south-west of the latter. 
 
 COLUMBA (NOAH'S DOVE). MAP III. 
 
 80. This constellation is situated about 16 S. of tho Hare, 
 and is nearly on the same meridian with the " Three Stors," in 
 the belt of Orion. It contains only 10 stars ; one of the 2d, 
 one of the 3d, and two of the 4th magnitudes ; of these Phaet 
 and Beta are the brightest, and are about 2 apart. Phaet, 
 the principal star, lies on the right, and is the highest of the 
 two ; Beta may be known by means of a smaller star just east 
 of it, marked Gamma. A line drawn from the easternmost star 
 in the belt of Orion, 32 directly south, will point out Phaet ; it, 
 is also 11^- S. of the lower left-hand star in the square of the 
 Hare, and makes with Sirius and Naos, in the ship, a large equi- 
 lateral triangle. 
 
 79. What other name has Alpha ; and with Beta what does it form ? What further 
 description ? 
 
 HISTORY. Why was Lepus placed in the heavens? 
 
 TELESCOPIC OBJECTS. Alpha ? Beta? Gamma? Iota? Kappa? Nebula? 
 
 80. Situaticn of Columba? Number and size of stars? The two brightest, and situa- 
 tion ? How find Phat ? What figure does it help to form ? With what other stars ? 
 
ERIDANUS. 47 
 
 HISTORY. 
 
 This constellation is so called in commemoration of the dove wh ch Noah " seat forth 
 to sec if the waters were abated from off the face of the groun.l," after (he ark had 
 rested on mount Ararat. " And the dove came in to him in the evening, and lo, in her 
 mouth was an olive leaf plucked off. 
 
 1 The surer messenger, 
 
 A dove sent forth once and again to spy 
 Green tree or ground, whereon his foot may light : 
 The second time returning in his bill 
 An olive leaf ho brings, pacific sign 1" 
 
 ERTDANUS (THE RIVER PO). MAP III. 
 
 81. This constellation meanders over a large and very irregu- 
 lar space in the heavens. It is not easy, nor scarcely desirable, 
 to trace oat all its windings among the stars. Its entire length 
 is riot less than 130 ; which, for the sake of a more easy refer- 
 ence, 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 thv3 Southern stream. 
 
 82. The Northern stream commences near Rigel, in the foot of 
 Orion, and flows out westerly, in a serpentine course nearly 40 
 to the Whale, where it suddenly makes a complete circuit, and 
 returns back nearly the same distance towards its source, but 
 bending gradually down toward the south, when it again makes 
 a similar circuit to the S. W., and finally disappears below the 
 horizon. 
 
 West of Rigel th*rf-e are five or six stars of the 3d and 4th magnitudes, arching up in a 
 femi-circular form, a-d marking the Jimi bend of the northern stream. About 8" below 
 these, or 19 W. of ll.pel, is a bright star of the 2d magnitude, in the second bend of the 
 northern stream, marked Gamma. This star culminates la minutes after the Pleiades, 
 and one hour and a quarter before Rigel. Passing Gamma, and a smaller star west of 
 it, there are four stars nearly in a row, which bring us to the breast of ('--tus. 8 N. of 
 Garnma, is a small stai named Kied> which is thought by some to be considerably neivr 
 the earth than Sinus. 
 
 Tlieemim, in the southern stream, is a star of the 3d magnitude, about 17* S. W. of 
 the square in Lepus, ami may be known by means of a smaller star 1 above it. Acker- 
 n((r is a brilliant star of the 1st magnitude, in the extremity of the southern stream; 
 but having 53 of S. declination, can never be seen in this latitude. 
 
 83. The whole number of stars in this constellation is 84 ; 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. 
 
 HISTORY Origin of this constellation ? 
 
 81. What said of Eridauus? Length? How divided? 82. Trace the Northern 
 Ureain? Gamma? Theemim? Achernar? 88. Whole number of stars in Eridauo* ? 
 
48 ASTRONOMY. 
 
 84. In the upper part of the Northern stream, near the feet 
 of Taurus, nay be seen a modern, but now discarded constella- 
 tion, of which Captain Smyth says: "Abbe Hell (who also 
 placed Herschel's Telescope among the celestials) has squeezed 
 in his Harpa Georgii, to compliment a sovereign of those realms ; 
 having niched from Eridanus about thirty or forty stars, some 
 of the 4th magnitude, for the purpose. 
 
 HISTORY. 
 
 Eridanus is the name of a celebrated river in Cisalpine Gaul, also called Padus. Itrf 
 modern name is Po. Virgil calls it the king of rivers. The Latin poets have rendered 
 it memorable from its connection with the fable of Phaeton, who, being a son of Phoebus 
 and Clymene, became a favorite of Venus, who intrusted him with the care of one of 
 her temples. This favor of the goddess made him vain, and he sought of his father a 
 public and incontestable sign of his tenderness, that should convince the world of his 
 origin. Phoebus, after some hesitation, made oath that he would grant him whatever 
 be required, and ao sooner was the oath uttered, than 
 
 " The youth, transported, asks without delay, 
 
 To guide the sun's bright chariot for a day. 
 
 The god repented of the oath he took, 
 
 For anguish thrice his radiant head he shook; 
 
 My son, says he, some other proof require, 
 
 Rash was my promise, rash was thy desire 
 
 Not Jove himself, the ruler of the sky, 
 
 That hurls the three-forked thunder from above, 
 
 Dares try his strength ; yet who as strong as Jove? 
 
 Besides, consider what impetuous force 
 
 Turns stars aud planets in a diflti rent course. 
 
 I steer against their motions ; nor am I 
 
 Borne buck by all the current of the sky: 
 
 But how could you resist the orbs that roll 
 
 In adverse whirls, anJ stem the rapid po'e?" 
 
 Phoebus represented the dangers to which he would be exposed in vain. He under- 
 took the afirial journey, and the explicit directions of his father were forgotten. No 
 sooner had Phaeton received the reins than he betrayed his ignorance of the manner 
 of guiding the chariot. The flying coursers became sensible of the confusion of their 
 driver, and immediately departed from the usual track. Phaeton repented too late of 
 his rashness, and already heaven and earth were threatened with a universal confla- 
 gration as the consequence, when Jupiter, perceiving the disorder of the horses, struck 
 the driver with a thunderbolt, and hurled him headlong from heaven into the rivet 
 Eridanus. His body, consumed with fire, was found by the nymphs of the place, wh 
 honored him with a decent burial, and inscribed this epitaph upon his tomb: 
 u lf> situs e&t Phaeton^ currus auriga pnterni .' 
 
 Queue si non tenuit, magnits tamen excidit ausi*." 
 
 His sisters mourned his unhappy end, and were changed by Jupiter into poplars. 
 "All the long night their mournful watch they keep, 
 
 And all the day stand round the tomb and weep." OVID. 
 
 It is said the tears which they shed turned to amber, with which the Phoenicians 
 and Carthaginians carried on in secrecy a most lucrative trade. The great heat pro- 
 duced on the occasion of the sun's departing out of his usual course, is said to have 
 dried up the blood of the Ethiopians, and turned their skins black; and to have pro- 
 duced sterility and barrenness over the greater part of Libya. 
 
 "At once from life and from the chariot driven, 
 Th* ambitious boy fell thunderstruck from heaven.** 
 
 W. What discarded constellation mentioned? Is it on the mapT Remark of Capt. 
 Bmyth? 
 
 . Named after what? Modern name? Fable of Phaeton? Its evidcn* 
 
 allusion:- 
 
AURIGA. 49 
 
 **The breathless Phaeton, with flaming hah, 
 Shot from the chariot like a falling star, 
 That in a summer's evening from the top 
 Of heaven drops down, or seems at least to drop, 
 Till on the Po his blasted corpse was hurl'd, 
 Far from his country, in the western world." 
 
 The fable of Phaeton evidently alludes to some extraordinary heats which wer 
 exoerienced in a very remote period, and of which only thia confused tradition hai 
 defended to later times. 
 
 TELESCOPIC OBJECTS. 
 
 1. /? ERIDANT A bright star with a distant telescopic companion, on the shin bone of 
 Orion ; R. A. 4h. 59m. 59s. ; Dec. S. 5 17' 9'. A 3, topaz yellow ; B 12, pale blue. TLi* 
 star is just above Rigel, in the direction of the Hyades. 
 
 2. y EHIDANI A star with a distant companion ; R. A. 3h. 50m. 34s. ; Dec. S. 13* 5S'. 
 A 2J$, yellow; B 10 pale grey. 
 
 8. A MILK WHITE NEBULA ; R. A. 3h. 33m. 02s. ; Dec. S. 19* 04' 8*. Pale, distinct, round, 
 and bright in the centre. 
 
 4. A PLANETARY NEBULA; R. A. 4h. 06m. 50s. ; Dec. S. 13* 09' 1*. About 4%" from y 
 in the direction of Kigel. A splendid though not very conspicuous object, of a greyish 
 white color. Map VIII., Fig. 34, represents it in its best aspects, highly magnified, 
 with four telescopic stars in the field, two of which point exactly towards the nebula. 
 
 SCEPTRUM BRANDEKBURGITJM (SCEPTEB OF BRANDENBURG). 
 MAP III. 
 
 85. This is a slender constellation, situated between the two 
 streams of theHiver Po. It was constructed by Kirch, in 1688, 
 and recognized by Bode a century afterwards; but is now gene- 
 rally discarded, though retained on the map. It is composed of 
 four stars of the 3d, 4th and 5th magnitudes, running north anfl 
 south; and is usually included in Eridanus. 
 
 AURIGA (THE CHARIOTEER). MAP III. 
 
 86. The Charioteer, called also the Wagoner, is represented 
 on the celestial map by the figure of a man in a reclining posture, 
 resting one foot upon the horn of Taurus, with a goat and her 
 kids in his left hand, and a bridle in his right. 
 
 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 overhead 
 in New England. It is on the same meridian with Orion, and 
 culminates at the same hour of the night. Both of these con- 
 stellations are on the meridian at 9 o'clock on the 24th of 
 
 . Beta? Gamma? Nebula? Point out on the map. 
 85. Describe the Sceptre of Brandenburgh ? Situation? When and by whom consti- 
 tuted? Is it recognized by astronomers? Number and magnitude of stars? 86. liow 
 is Auriga represented? Situation? When on the meridian? 
 
60 ASTRONOMY. 
 
 January, and 1 hour and 40 minutes east of it on the 1st of 
 January. 
 
 87. The whole number of visible stars in Auriga, is 66, 
 incl tiding one of the 1st and one of the 2d magnitude, which 
 mark the shoulders. Capella is the principal star in this con- 
 stellation, 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 sharp-pointed triangle formed by three stars, 3 or 4 
 this side of it, on the left. It is also 18 N. of El Nath, which 
 is common to the northern horn of Taurus, and the right foot 
 of Auriga. Capella comes to the meridian on the 19th of 
 January, just 2 minutes before Rigel, in the foot of Orion, 
 which it very much resembles in brightness. 
 
 Menkalina, in the east shoulder, is a star of the 2d magnitude, 7%' E. of Capella, and 
 culminates the next minute after Betelguese, 31% S. of it. Theta, in the right arm, 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 Orioi, and opposite 
 to them. Again, the two stars in the shoulders of Auriga, with the two in the shoulders 
 of Orion, mark the extremities 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 in Orion, make two slender and similar triangles, both meeting in a common point, 
 half way between them at El Nath, in the northern horn of Taurus. 
 
 Dcltit, 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 height 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 . to the heel, 
 on Ihe top of the horn : both figures together resembling an elongated diamond. 
 
 Delta in the head, Menkalina in the right shoulder, and Theta in the arm of Auriga, 
 make a straight line with Betelguese in Orion, Delta in the square of the Hare, and Beta 
 In Noah's Dove ; all being very nearly on the same meridian, 48 W. of the solstitial 
 eolure. 
 
 " 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." JSudosia. 
 
 HISTORY. 
 
 The Greeks give various accounts of this constellation ; some supposed it to be Erieh- 
 Ihonius, the fourth king of Athens, and son of Vulcan and Minerva, who awarded him a 
 r.laoe among the constellations on account of his many useful inventions. He waa o* a 
 monstrous shape. He is said to have invented chariots, and to have excelled all other" 
 In the management of horses. In allusion to this, Virgil has the following lines 
 " Primus Erichthonius currus et quatuor ausus 
 Jungere equos, rapidisque rotis insistere victor." 
 
 Georgic. Lib. iii. p. 118. 
 
 M BoUl Erichthonius was the first who join'd 
 Four horses for the rapid race design'd, 
 And o'er the dusty wheels presiding sat." Dryden. 
 
 87. Number of stars visible? Mngnitndfi and situation of Capella? How kmywrtf 
 (denkalina? Delta compared wiih Theta? 
 
 The first supposition ? Second? Third? Opinion of Jamieson 
 
CAMELOPARDALUS. 51 
 
 Other writers say that Bootes invented the chariot, and that Auriga was the son of 
 Mercury, and charioteer to (Enomaus, king of Pisa, and so experienced, that he rendered 
 his horses the swiftest in all Greece. But as neither of these fables seems to account for 
 the goat and her kids, it has been supposed that they refer to Amalthaea and her sister 
 Melissa, who fed Jupiter, during his infancy, with goat's milk, and that, as a reward for 
 their kindness, they were placed in the heavens. But there is no reason assigned for 
 their being placed in the arms of Auriga, and the inference is unavoidable, that 
 mythology is at fault on this point. 
 
 Jamieson is of opinian that Auriga is a mere type or scientific symbol of the beautiful 
 fable of Phaeton, because he was the attendant of Phoebus at that remote period when 
 Taurus opened the year. 
 
 TELESCOPIC OBJECTS. 
 
 1. a AURIGA (Oapella) A fine star with two distant companions, on the right shoulder- 
 blade of Auriga ; R. A. 5h. 04m. 63s. ; Dec. N. 45" 49' 07". A 1, bright white ; B 12, pale 
 blue ; C 9, grey. 
 
 2. {3 AURIGA (Menkalina) A bright star in the left shoulder, with a distant com- 
 panion ; R. A. 5h. 47m. 4Ss. ; Dec. N. 44 55' 3". A 2, yellow; B 10 j, bluish. 
 
 3. A RICH CLUSTER of minute staiA, on the left thigh; R. A. 5h. 18m. 41s. ; Dec. N. 85* 
 44' 9" A singular figure, somewhat like a cross. Find by a line from Rigel, northwards 
 through (3 Tauri, and about 7 beyond. 
 
 4. A RESOLVABLE NEBULA ; R. A. 6l , 20ra. 5ls. ; Dec. N. 34 06' 9'. Situated in a rich 
 field of minute stars. 
 
 CAMELOPARDALUS (THE OAMELOPAED). MAP YI. 
 
 88. This constellation was made by Hevelius out of the 
 unformed stars which lay scattered between Perseus, Auriga, 
 the head of Ursa Major, and the Pole star.* It is situated 
 directly N. of Auriga and the head of the Lynx, and occupies 
 nearly all the space between these and the pole. It contains 58 
 small stars ; the five largest of which are only of the 4th mag- 
 nitude. 
 
 89. The principal star lies in the thigh, and is about 20 from 
 Capella, in a northerly direction. It marks the northern boun- 
 dary of the temperate zone ; being less than one degree S. of 
 the Arctic circle. There are two other stars of the 4th magni- 
 tude, near the 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. 
 
 HISTORY. 
 
 The Camelopard is so called from an animal of that name, peculiar to Ethiopia. This 
 animal resembles both the camel and the leopard. Its body is spotted like that of tho 
 leopard. Its neck is about seven feet long, its fore and hind legs from the hoof to tue 
 Beyond joint, are nearly of the same length ; but from the second joint of the legs to the 
 r/ody, the fore legs are so long in comparison with the hind ones, that no person could si* 
 upon its back without instantly sliding off, as from a horse that stood up on his hind feet 
 
 TELESCOPIC OBJECTS. Alpha ? Beta? Cluster? Nebulae? 
 
 88. Origin of Camelopardalus? Situation and ejctent? Number and size of its Ft.\rs? 
 C9. Where is its prin ;ipal star ? The next two ? "How known ? 
 
 . Any mythological story? What said of the anim-\l? 
 
 B.G. 3 
 
52 ASTRONOMY. 
 
 TELESCOPIC OBJECTS. 
 
 1. a CAMELOPARDALI A neat DOUBLE STAR between the hind feet of the animal, half way 
 between a Persei and 6 in the head of Auriga ; R. A. 4h. 19m. 23s. ; Dec. N. 53 33 3" 
 A 7J$, white; B 8J, sapphire blue. 
 
 2. Another close DOUBLB STAB, between the hind feet ; B. A. 4h. 27m. 18s. ; Dec. N. 63* 
 09'. A 5J$, yellow ; B. 73*. pale blue. 
 
 8. A very delicate DOUBLE STAR in the animal's hind hoof; R. A. 4h. 44m. 28s. ; Dec. N 
 53 29' 3". A 5, white ; B 13, orange. 
 
 4. A fine DOUBLE STAR in the lower part of the back of the neck ; R. A. 4h. 46m. 19s. 
 Dec. N. 79 01' 8". A 5%, light yellow ; B 9, pale blue. 
 
 5. A bright PLANETA*? NEBULA, of a bluish white tint, about 60* in diameter, in the 
 nind flank of the animal, R. A. 4h. 53m. 29s. Dec. N. 60 23' 5". A curious body, in H 
 rich field of small stars. 
 
 CHAPTER IV. 
 
 CONSTELLATIONS ON THE MERIDIAN IN FEBRUARY. 
 
 THE LYNX. MAPS III. AND VI. 
 
 90. THIS constellation, 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 N. of Gemini, and between Auriga and Ursa 
 Major. 
 
 91. The whole number of stars in this constellation is 44, 
 including only three that are So large as the 3d magnitude. 
 The largest of these, near the mouth, is in the solstitial colure, 
 14 N. of Menkalina, in the E. shoulder of Auriga. The other 
 two principal stars are in the brush of the tail, 3 S. W. of 
 another star of the same brightness in the mouth of the Lesser 
 Lion, with which it makes a small triangle. Its centre is on 
 the meridian at 9 o'clock on the 23d, or at half-past t on the 1st 
 of February. 
 
 TELESCOPIC OBJECTS. 
 
 1. A close DOUBLE STAR, in the nose of the Lynx ; R. A. 6h. 07m. 51s. ; Dec. N. 59* 25' 8' 
 About 30 from the Pole star, on a line toward Sirius. A 6, and B 7^, both white. An 
 elegant but difficult object. 
 
 2. A close DOUBLE STAR in the eye of the Lynx, between Dubhi and Capella; R. A. 6h 
 38m. 57s. ; Dec. N. 59 37' 6". A 5J^, golden yellow ; B 7, purple. A delicate and pretty 
 object. 
 
 3. A coarse TRIPLE STAR on the animal's lower jaw; R. A. 6h. 12m. 50s. ; Dec. N. 58 s 
 29' 7". A. 6, orange tinge ; B 13, blue ; and C 9, pale garnet. 
 
 4. A ROUND NEBULA, in the Lynx, or fore paws of Leo Minor ; R. A. 9h. 14m. 82s. 
 Dec. N. 35 11' 9'. It is pale white, sparkling in the centre. 
 
 TELESCOPIC OBJECTS. Alpha? What other double stars? Nebula? 
 90. Describe the Lynx ? Situation? 91. Number and size of its stars? Where is the 
 Urgest situated? The other two principal stars? 
 TKLBBOOPIC OBJECTS. What double stars T Triple? NebuU 
 
GEMINI. 53 
 
 TELESCOPIUM HERSCHELLII (HEESOHEL'S TELESCOPE). 
 MAP III. 
 
 92. About midway between the body of the Lynx and Gemini, 
 may be seen the rude figure of a refracting Telescope, with its 
 stand. It was made out of a few unformed stars, by Abbe 
 Hell, in honor of Sir William Herschel, but is now generally 
 discarded. It is reta. aed on the map more as a matter of history 
 than to perpetuate it as a constellation. 
 
 GEMINI (THE TWINS). MAP III. 
 
 93. This constellation represents, in a sitting posture, the twin 
 brothers, Castor and Pollux. It 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. 
 
 94. The plane of the Ecliptic passes through the centre of 
 Gemini ; and as the earth moves round in her orbit from the first 
 point of Aries to the same point again, the sun, in the mean- 
 time, 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 lustre of the 
 stars is obscured by the superior effulgence of the sun. 
 
 "When the sun is just entering the outlines of a constellation eastward, its eastern limit 
 may be seen in the evening twilight, just above the setting sun. So when the sun has 
 arrived at the eastern limit of a constellation, the western part of it may be seen rising 
 in the morning twilight, just before the rising sun. Under other circumstances, when 
 the sun is said to be in, or to enter, a particular constellation, it is to be understood that 
 that 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 through the night. Also, whatever constel- 
 lation 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 centre 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 tho 
 west, and will come to the meridian at midnight; being then exactly opposite the sun. 
 And as the stars gain upon the sun at the rate of two hours every month, it follows thjtf. 
 the centre of this constellation will, on the 17th of February, come to the meridian thrco 
 liours earlier, or at 9 o'clock in the evening. 
 
 The sun is in the vernal equinox about the 21st of March, from whence it advances 
 
 92. What said of Herschel's Telescope? Why perpetuated on the map? 93. How ia 
 (Jenvlni represented ? Its order in the signs, &c. ? Situation ? 94. How with respect 
 ':.> t">e Ecliptic? What result from this fact? What remarks respecting the sun and 
 >' at filiations ? 
 
54 ASTRONOMY. 
 
 through one sign or constellation every succeeding mjnth thereafter; and that eacla 
 constellation is one month in advance of the sign of that name: wherefore, reckoi 
 Pisces in March, Aries in April, Taurus in May, and Gemini in June, Ac., beginning witb 
 each constellation at the 21st, or 22d of the month. 
 
 95. Gemini contains 85 stars, including two of the 2d, three 
 of the 3d, and six of the 4th magnitudes. It is readily recog- 
 nized by means of the two principal stars, Castor and Pollux, 
 of the 1st and 2d magnitudes, in the heads of the Twins, about 
 4 apart. 
 
 Thare being only 11 minutes' difference in the transit of these two stars over the meri- 
 Cian, *hey may both be considered as culminating at 9 o'clock about the 24th of Febru- 
 ary. Castor, in the head of Castor, is a star of the 1st magnitude, 4^ N. W. of Pol- 
 ux, 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 4% 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." 
 
 96. The relative magnitude or brightness of these stars has 
 undergone considerable changes at different 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 25 years, ascribes the varia- 
 tion 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. 
 
 Bradley 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 centre between them, in orbits nearly circu- 
 lar, as two balls attached to a rod would do, if suspended by a string affixed to the cen- 
 tre 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." 
 
 97. 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, 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 Gamma, mark Cas- 
 tor'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. 
 
 95. Number of stars in Gemini? Magnitudes? How recognize this constellation? 
 What said of the culmination of Castor, and of Pollux ? 96. Are they variable ? What 
 did Bradley and Maskelyne ascertain? Remark of Bowditch? 97. What constitute 
 Gemini ? Alheua ? How situated ? What mark the kneea? 
 
GEMINI. 55 
 
 98. There are, in this constellation, two other remarkable 
 parallel rows, lying at right angles with the former ; one, lead- 
 ing from the head to the foot of Castor, the brightest star being 
 in the middle, and in the knee : the other, leading from the 
 head to the foot of Pollux, "the brightest star, called Wasat, 
 being in the body, and Zeta, next below it, in the knee. 
 
 Wasat is in the ecliptic, and very near the center of the constellation. The two stsrs, 
 Mu and Tejat, in the northern foot, are also very near the ecliptic; Tejat is a small star 
 of between the 4th and 5th magnitudes, 2" W. of Mu, and deserves to be noticed because 
 it marks the spot of the summer solstice, in the tropic of Cancer, just where the sun is on 
 the longest day of the year, and is, moreover, the dividing limit between the torrid and 
 the N. temperate zone. 
 
 Propus, also in the ecliptic, 2Jg W. of Tejat, is a star of only the 5th magnitude, but 
 rendered memorable as being the star which served for many years to determine the 
 position of the planet Herschel, after its first discovery. 
 
 HISTORY. 
 
 Castor and Pollux were twin brothers, sons of Jupiter, by Leda, the wife of Tyndarus, 
 king of Sparta. The manner of their birth was very singular. They were educated at 
 Pallena, and afterwards embarked with Jason in the celebrated contest for the golden 
 fleece, at Colchis; on which occasion they behaved with unparalleled courage and 
 bravery. Pollux distinguished himself by his achievements in arms and personal 
 prowess, and Castor in equestrian exercises and the management of horses ; whence they 
 are represented, in the temples of Greece, on white horses, armed with spears, riding 
 Bide by side, their heads crowned with a petasus, on whose top glitters a star. Among 
 the ancients, and especially among the Romans, there prevailed a superstition that 
 Castor and Pollux often appeared at the head of their armies, and led on their troops to 
 battle and to victory. 
 
 " Castor and Pollux, first In martial force, 
 
 One bold on foot, and one renown'd for horse. 
 
 Fair Leda's twins in time to stars decreed, 
 
 One fought on foot, one curb'd the fiery steed." Virgil. 
 * Castor alert to tame the foaming steed, 
 
 And Pollux strong to deal the manly deed." Martial. 
 
 The brothers cleared the Hellespont and the neighboring seas from pirates after theh 
 return from Colchis ; from which circumstance they have ever since been regarded as 
 the friends and protectors of navigation. In the Argonautic expedition during a violent 
 storm, it is said two flames of fire were seen to play around their heads, and immediately 
 the tempest ceased, and the sea was calm. From this circumstance, the sailors inferred, 
 that whenever both fires appeared in the sky, it would be fair weather ; but when only 
 one appeared, there would be storms. 
 
 St. Paul, after being wrecked on the island of Melita, embarked for Rome "in a ship 
 whose sign was Castor and Pollute;" so formed, no doubt, in accordance with the popu- 
 lar belief that these divinities presided over the science and safety of navigation. 
 
 They were initiated into the sacred mysteries of Cabiri, and into those of Ceres at 
 Eleusis. They were invited to a feast at which Lynceus and Idas were going to celebrate 
 their nuptials. with Phoebe and Telaria, the daughters of Leucippus, brother to Tyndarus. 
 They became enamored of the daughters, who were about to be married, and resolved to 
 supplant their rivals : a battle ensued, in which Castor killed Lynceus, and was himself 
 killed by Idas. Pollux revenged the death of his brother by killing Idas ; but being him- 
 self immortal and most tenderly attached to his deceased brother, he was unwilling to 
 survive him; he therefore entreated Jupiter to restore him to life, or to be deprived him- 
 self of immortality ; wherefore, Jupiter permitted Castor, who had been slain, tc share 
 the immortality of Pollux; and consequently as long as the one was upon earth, so long 
 was the other detained in the infernal regions, and they alternately lived and died every 
 day. Jupiter also further rewarded their fraternal attachment by changing them both 
 
 98. What other remarkable rows of stars in Gemini ? Situation of Wasat f Of Tejat? 
 Of ProjmsT 
 
 HISTORY. Myth of the parentage of Gemini ? Their achievements? Roman super Hl- 
 >jon ? That of sailors ? Allusion of St. Paul ? Story of the fatal wedding ? 
 
56 ASTRONOMY. 
 
 into a constellation under the name of Gemini, TWVM, which, it ts strangely pretended, 
 never appear together, but when one rises the other sets, and so on, alternately. 
 
 " By turns they visit this ethereal sky, 
 
 And live alternate, and alternate die." Homer. 
 M Pollux, cflering his alternate life, 
 Could free his brother, and could daily go 
 By turns aloft, by turns descend below." Virgil. 
 
 Castor and Pollux were worshiped both by the Greeks and Romans, who sacrificefl 
 white lambs upon their altars. In the Hebrew Zodiac, the constellation of the Twin-j 
 refers to the tribe of Benjamin. 
 
 TELESCOPIC OBJECTS. 
 
 1. a GEMINORUM (Castor) A neat DOUBLE STAR; R. A. 7h. 24m. 23s.; Dec. N. 82 e 14'- 
 A 3. bright white; B 3}, pale white; with a third star of the llth magnitude about 72 
 distant. A Binary System, with a probable period of 232 years. A beautiful object, and 
 easily found. Map VIII. , Fig. 4.- 
 
 2. ft GEMINORUM A QUADRUPLE STAR in the eye of Pollux, R. A. 7h. 85m. 31s.; Dec 
 N. 28 25' 4". A 2, orange tinge ; B 12, ash-colored ; C 11, pale violet, with another 
 minute companion visible with the best instruments. 
 
 8. y GEMINORUM (Alhena)A coarse TRIPLE STAR, in the right foot of Pollux i R. A. 
 6h. 28m. 28s. ; Dec. N. 16 31' S". ; A 3, brilliant white ; B 13, and C 12, both pale plum 
 color. It is on a line from Rigel to ft Geminorum, and nearest the former. 
 
 4. J GEMINORUM (Wasaf) A DOUBLE STAR on the right hip of Pollux; R. A. 7h. 10m. 
 84s. ; Dec. N. 22 16' 3'. A 3 j, pale white ; B 9, purple. 
 
 5. e GEMINORUM (Melucta) A star with a distant companion, on Castor's rfght knee ; 
 R. A. 6h. 34m. 05s. ; Dec. N. 25- 16' 9". A 3, white ; B 9>, cerulean blue. 
 
 6. ^ GEMINORUM A coarse TRIPLE STAR on the right knee of Pollux ; R. A. 6h. 54m. 37s. ; 
 Dec. N. 20 47' 9". A 4, pale topaz ; B 8, violet ; C 18, grey. 
 
 7. A CLUSTER, near the right foot of Castor ; R. A. 5h. 59m. Ols. ; Dec. N. 24" 21' 8". A 
 gorgeous field of stars from the 9th to the 16th magnitudes. 
 
 8. A CLUSTER in the calf of Pollux's right leg; R. A. 6h. 45m. 56s. ; Dec. N. 18 10' 5". 
 A faint angular group of extremely small stars, in a rich region, but seen with difficulty. 
 See Map VIII., Fig. 35. 
 
 9. A COMPRESSED CLUSTER under the left shoulder of Pollux; one-third the distance 
 from ft Geminorum, to ft Canis Minoris ; R. A. 7h. 28m. 57s. ; Dec. N. 21 55' 7'. A 
 faint object about 12 in diameter, with a small star near the centre. Map VHL, Fig. 36. 
 
 , CANIS MINOR (THE LITTLE DOG). MAP III. 
 
 99. This small constellation is situated about 5 N. of the equi- 
 noctial, and midway between Canis Major and the Twins. It 
 contains 14 stars, of which two are very brilliant. The brightest 
 star is called Procyon. It is or* the 1st magnitude, and is about 
 4 S. E. of the next brightest, marked Gomelza, which is of the 
 3d magnitude. These two stars resemble the two in the head 
 of the Twins. Procyon, in the Little Dog, is 23 S. of Pollux 
 in Gemini, and Gomelza is about the same distance S. of Castor. 
 
 100. A great number of geometrical figures may be formed 
 of the principal stars in the vicinity of the Little Dog. For 
 example : Procyon is 23 S. of Pollux, and 26 E. of Betel- 
 
 TELESCOPIC OBJECTS. Alpha? Beta? Gamma? Delta, Ac.? Clusters? Which 
 Shown on the map ? 
 
 99. Where is Canis Minor situated? Number of stars? Name of brightest ? Mag- 
 litude? Next brightest? What do these two resemble? 100. What said of geome- 
 Tical figures? Of the name Procyon? Its import? 
 
CANIS MINOR. 5 
 
 guese, and forms with them a large right-angled triangle 
 Again, Procyon is equi-distant from Betelguese and Sirius, and 
 forms with them an equilateral triangle whose sides are each 
 about 26. If a straight line, connecting Procyon and Sirius, 
 be produced 23 farther, it will point out Phaet, in the Dove. 
 
 Procyon is often taken for the name of the Little Dog, or for the whole constellation, 
 c.s Sirius is for the greater one ; hence it is common to refer to either of these constel- 
 lations by the name of its principal star. Procyon comes to the meridian 53 minute 
 after Sirius, on the 24th of February ; although it rises, in this latitude, about half an 
 hour before it. For this reason, it was called Procyon^ from two Greek words which 
 signify (Ante Canis) " before the dog." 
 
 HISTORY. 
 
 .The Little Dog, according to Greek fable, is one of Orion's hounds. Some suppose it 
 refers to the Egyptian god Anubis, which was represented with a dog's head ; others to 
 Diana, the goddess of hunting ; and others, that it is the faithful dog Maera, which 
 belonged to Icarus, and discovered to his daughter Erigone the place of his burial. 
 Others, again, say it is one of Actaeon's hounds that devoured their master, after LMaiia 
 had transformed him into a stag, to prevent, as she said, his betraying her. 
 " This said, the man began to disappear 
 By slow degrees, and ended in a deer. 
 Transform'd at length, he flies away in haste, 
 And wonders why he flies so fast 
 But as by chance, within a neighb'ring brook, 
 He saw his branching horns, and alter'd look, 
 Wretched Acteon ! in a doleful tone 
 He tried to speak, but only gave a groan ; 
 And as he wept, within the watery glass, 
 He saw the big round drops, with silent pace, 
 Run trickling down a savage, hairy face. 
 What should he do ? or seek his old abodes, 
 Or herd among the deer, and skulk in woods? 
 As he thus ponders, he behind him spies 
 His opening hounds, and now he hears their cries. 
 From shouting men, and horns, and dogs he flies. 
 When now tlie fleetest of the pack that press'd 
 Close at his heels, and sprung before the rest, 
 Had fastened on him, straight another pair 
 Hung on his wounded side, and held him there, 
 Till all the pack came up, and every hound 
 Tore the sad huntsman groveling on the ground." 
 
 It is not difficult to deduce the moral of this fable. The selfishness and caprice of 
 human friendship furnish daily illustrations of it. While the good man, the philanthro- 
 pist, or the public benefactor, is in affluent circumstances, and, with a heart to devise, 
 has the power to minister blessings to his numerous beneficiaries, his virtues are the 
 general theme ; but when adverse storms have changed the ability, though they could 
 not shake the will of their benefactor, he is straightway pursued, like Actaeon, by his own 
 hounds; and, like Actaeon, he is "torn to the ground" by the fangs that fed upon his 
 bounty. 
 
 It is most probable, however, that the Egyptians were the inventors of this con- 
 otellation ; and as it always rises a little before the Dog Star, which, at a particular 
 season, they so much dreaded, it is properly represented as a little watchful crea 
 */ure, giving notice like a faithful sentinel of the other's approach. 
 
 TELESCOPIC OBJECTS. 
 
 1. a CANIS MINORIS (Procyon) A bright star in the loins of the Jog with a distan 
 -.ompamon ; R. A. Th. 30m. 55s ; Dec. N. 5 37' 8". A 1 J$, yellowish white ; B 8, orango 
 'int. Several small stars in the field. 
 
 HISTORY. What is the Little Dog supposed to represent? Fable of ActsconV I*e 
 moral ? Who probably invented this constellation ? To represent what? 
 TELESCOPIC OBJECTS. Alpha ? Beta ? Double star ? Triple ? 
 
58 ASTRONOMY. 
 
 2. (3 CANTS MINORIS (Gomelza) A wide TRIPLK STAR in theneck; R. A. 7h. ISm. 28s 
 Dec. N. 8 86' 4". A 3, white ; B 12, orange ; C 10, flushed the last coarsely double with 
 one of the same magnitude. Other stars in the field. 
 
 8. A close DOUBLE STAR, in a fine vicinity in the loins ; R. A. 7h. 81m. 37s. ; Dec. N. 5" 
 85' 7*. A 7, white ; B 8, ash-colored, with a minute blue star 2' distant. 
 
 4. A WIDE TRIPLE STAR, 6" S. E. of Procyon ; R. A. 7h. 50rn. 03s. ; Dec. N. 2" 38' 8". A 
 6, pale white ; B 8, bluish ; C 9, blue. 
 
 MONOCEROS (THE UNIOOBN). MAP III. 
 
 101. This is a modern constellation, made out of the unformed 
 stars of the ancients that lay scattered over a large space of 
 the heavens between the two Dogs. It extends a considerable 
 distance on each side of the equinoctial, and its centre is on the 
 same meridian with Procyon. 
 
 102. It contains 31 small stars, of which the seven principal 
 ones are of only the 4th magnitude. Three of these are situ- 
 ated in the head, 3 or 4 apart, forming a straight line N. E. 
 and S. W. about 9 E. of Betelguese in Orion's shoulder, and 
 about the same distance S. of Albena in the foot of the twins. 
 
 The remaining stars in this constellation are scattered over a 
 large space, and being very small, are unworthy of particular 
 notice. 
 
 HISTORY. 
 
 The Monoceros 5s a species of the Unicorn or Rhinoceros. It is about the size of a 
 horse, with one white horn growing out of the middle of its forehead. It is said to exist 
 in the wilds of Ethiopia, and to be very formidable. 
 
 Naturalists say that, when pursued by the hunters, it precipitates itself from the 
 tops of the highest rocks, and pitches upon its horn, which sustains the whole force of 
 its fall, so that it receives no damage thereby. Sparmann informs us, that the figure of 
 the unicorn, described by some of the ancients, has been found delineated on the surface 
 of a rock in Caffraria ; and thence conjectures that such an animal, instead of being 
 fabulous, as some suppose, did once actually exist in Africa. Lobo affirms that he has 
 seen it. 
 
 The rhinoceros, which is akin to it, is found in Bengal, Siam, Cochin China, part of 
 China Proper, and the isles of Java and Sumatra. 
 
 TELESCOPIC OBJECTS. 
 
 1. A most delicate DOUBLE STAR (/), in the Unicorn's eye ; R. A. 6h. 26m. 06s. ; Dec. N. 
 7 41' 05". A 6, yellowish white : B 16, dusky. A difficult object. 
 
 2. A neat DOUBLE STAR (&), in the nostril, 7J^ east of Betelguese; R. A. 6h. 15m. 17s. ; 
 Dec. N. 4 40' 01". A 5%, golden yellow ; B 8, lilac. 
 
 3. A fine TRIPLE STAR in the right fore-leg; R. A. 6h. 21m. 04s.; Dec. S. 6* 56' 01". A 
 6J$, white ; B 7, and C 8, both pale white. A ray shot from the Bull's eye through Bella- 
 trix, and rather more than as far again, will pick it up. Supposed by Herschel to be a 
 triple system, periods A B 17,000 ys. B C 1000. Shown double only on the map of 
 the constellations. Telescopic view, Map VIII., Fig. 5. 
 
 4. A delicate TRIPLE STAR, in a magnificent stellar field, between the Unicorn's ears ; 
 R. A. 6h. 32m. 10s. ; Dec. N. 10 02' 02". One-third the distance from Procyon to Alle- 
 baron. A 6, greenish ; B 9%, pale grey ; C 15, blue. A fine object. 
 
 101. Character and situation of Monoceros? Extent? 102. Number and size of i(.P 
 stars ? How three of the largest situated? 
 
 HISTORY. What said of the animal itself? Is it not wholly fabulous ? 
 TELESCOPIC OBJECTS. Double stars ? Triple ? Any shown on the map ? 
 
CANIS MAJOit 59 
 
 CANTS MAJOR (THE GREAT DOG). MAP El. 
 
 103. This interesting constellation is situated southward and 
 eastward of Orion, and is universally known by the brilliance 
 of its principal star, Sirius, which is apparently the largest and 
 brightest in the heavens. It glows in the winter hemisphere with 
 a lustre which is unequaled by any other star in the firmament. 
 Its distance from the earth, though computed at 20 millions 
 of millions of miles, is supposed to be less than that of any other 
 star : a distance, however, so great that a cannon ball, which 
 flies at the rate of 19 miles a minute, would be two millions of 
 years in passing over the mighty interval ; while sound, moving 
 at the rate of 13 miles a minute, would reach Sirius in little less 
 than three millions of years. 
 
 It may be shown in the same manner, that a ray of light, which occupies only 8 minutes 
 and 13 seconds in coming to us from the sun, which is at the rate of nearly two hundred 
 thousand miles a second, would be 3 years and 82 days in passing through the vast space 
 that lies between Sirius and the earth. Consequently, were it blotted from the heavens, 
 Its light would continue visible to us for a period of 3 years and 82 days after it had 
 ceased to be. 
 
 If the nearest stars give such astonishing results, what shall we say of those which are 
 situated a thousand times as far beyond these, as these are from us ? 
 
 104. In the remote ages of the world, when every man was 
 his own astronomer, the rising and setting of Sirius, or the Dog 
 Star, as it is called, was watched with deep and various solici- 
 tude. The ancient Thebans, who first cultivated astronomy in 
 Egypt, determined the length of the year by the number of its 
 risings. The Egyptians watched its rising with mingled appre- 
 hensions of hope and fear ; as it was ominous to them of agri- 
 cultural prosperity or blighting drought. It foretold to them 
 the rising of the Nile, which they called Siris, and admonished 
 them when to sow. 
 
 105. The Romans were accustomed yearly to sacrifice a -dog 
 to Sirius, to render him propitious in his influence upon their 
 herds and fields. The eastern nations generally believed the 
 rising of Sirius would be productive of great heat on the earth. 
 
 Thus Virgil : 
 
 " Turn steriles -exurere Sirius agros ; 
 
 Ardebant herbse, et victum seges segra negabat." 
 
 Parched was the grass, and blighted was the corn: 
 
 Nor 'scape the beasts ; for Sirius from on high, 
 With pestilential heat infects the sky.'" 
 
 103. Situation of Canis Major? How known? Supposed distance of Sirius? Illuo 
 trsited by the speed of a cannon ball ? Of light ? 104. Uow was Sirius regarded by 'Jit- 
 undents? Use made of it by the Thebans? The Egyptians? 105. Practice of i!i* 
 Romans ? 
 
 O* 
 
60 ASTRONOMY. 
 
 106. Accordingly, to that season of the year when Sirius rose 
 with the sun and seemed to blend its own influence with the 
 heat of that luminary, the ancients gave the name of Dog-days, 
 (Dus canicularis.) At that remote period the Dog-days com- 
 menced on the 4th of August, or four days after the summer 
 solstice, and lasted forty days, or until the 14th of September. 
 At present the dog-days begin on the 3d of July, and continue 
 to the llth of August, being one day less than the ancients 
 reckoned. 
 
 107. Hence, it is plain that the Dog-days of the moderns 
 have no reference whatever to the rising of Sirius, or any other 
 star, because the time of their rising is perpetually accelerated 
 by the precession of the equinoxes : they have reference then 
 only to the summer solstice, which never changes its position in 
 respect to the seasons. 
 
 The time of Sirius' rising varies with the latitude of the place, and in the same latitude, 
 is sensibly changed after a course of years, on account of the precession of the equinoxes. 
 This enables us to determine with approximate accuracy, the dates of many events of 
 antiquity, which cannot be well determined by other records. We do not know, for 
 instance, in what precise period of the world Hesiod flourished. Yet he tells us in his 
 Opera el I>ies, lib. ii. v. 185, that Arcturus in his time rose heliacally, 60 days after the 
 winter solstice, which then was in the 9th degree of Aquarius, or 39 beyond its present 
 position. Now 39 : 50l*=2794 years since the time of Hesiod, which corresponds very 
 nearly with history. 
 
 108. When a star rose at sun-setting, or set at sun-rising, it 
 was called the Achronical rising or setting. When a planet or 
 star appeared above the horizon just before the sun, in the morn- 
 ing, it was called the Heliacal rising of the star ; and when it 
 sunk below the horizon immediately after the sun, in the evening, 
 it was called the Heliacal setting. 
 
 According to Ptolemy, stars of the first magnitude are seen rising and setting when the 
 sun is 12 below the horizon ; stars of the 2u magnitude require the sun's depression to 
 be 13; stars of the 3d magnitude, 14', and so on, allowing one degree for each magni- 
 tude. The rising and setting of the stars described in this way, since this mode of 
 derfc/iption often occurs in Hesiod, Virgil, Columella, Ovid, Pliny, &c., are called pojtwal 
 rising and setting. They served to mark the times of religious ceremonies, the seasons 
 allotted to the several departments of husbandry, and the overflowing of the Nile. 
 
 109. The student may be perplexed to understand how the 
 Dog Star, which he seldom sees till mid-winter, should be asso- 
 ciated with the most fervid heat of summer. This is explained 
 by considering that this star, in summer, is over our heads in 
 the daytime, and in the lower hemisphere at night. As " thick 
 the floor of heaven is inlaid with patines of bright gold," by day, 
 
 106. Origin of the phrase Dog-days? When did they begin in the time of Virgil? At 
 what time now? 107. What inference from these facts? What variation in the time 
 of Sirius' rising ? What calculation by knowing the time when Sirius rose, at any period V 
 10S. What are the Achronical and Heliacal rising or setting of a star or planet? Rr 
 mark of Ptolemy in regard to rising and setting of the stars ? 109. How is it that 
 Sirius a winter star, is associated with iue heat of summer? 
 
CANIS^ MAJOR. 61 
 
 as by night ; but on account of the superior splendor of the sun, 
 we cannot see them. 
 
 110 Sirius is situated nearly S. of Alhena, in the feet of the 
 Twins, and about as far S* of the equinoctial as Alhena is JST. 
 of it. It is about 10 E. of the Hare, and 26 S. of Betel- 
 
 fuese in Orion, with which it forms a large equilateral triangle, 
 t also forms a similar triangle with Phaet in the Dove, and 
 Naos in the Ship. These two triangles being joined at their 
 vertex in Sirius, present the figure of an enormous X, called by 
 some, the EGYPTIAN X. Sirius is also pointed out by the direc- 
 tion of the Three Stars in the belt of Orion. Its distance from 
 them is about 23. It comes to the meridian at 9 o'clock on 
 the llth of February. 
 
 111. Mirzam, in the foot of the Dog, is a star of the 2d mag- 
 nitude, 5|- W. of Sirius. A little above, and 4 or 5 to the 
 left, there are three stars of the 3d and 4th magnitudes, forming 
 a triangular figure somewhat resembling a dog's head. The 
 brightest of them, on the left, is called Muliphen. It entirely 
 disappeared in 1670, and was not seen again for more than 20 
 years. Since that time it has maintained a steady lustre. 
 
 112. Wesen is a star of between the 2d and 3d magnitudes, 
 In the back, 11 S. S. E. of Sirius, with which, and Mirzam in 
 the paw, it makes an elongated triangle. The two hinder feet 
 are marked by Naos and Lambda, stars of the 3d and 4th 
 magnitudes, situated about 3 apart, and 12 directly S. of the 
 fore foot. This constellation contains 31 visible stars, including 
 one of the 1st magnitude, four of the 2d, and two of the 3d ; 
 all of which are easily traced out by the aid of the map. 
 
 HISTORY. 
 
 Manilius, a Latin poet who flourished in the Augustan age, wrote an admirable poem, 
 .' Ive books, upon the fixed sta"-", in which he thus speaks of this constellation : 
 " All others he excels ; no fairer light 
 
 Ascends the skies, none sets so clear and bright." 
 Jt>u.' EUDOSIA best describes it 
 
 " Next shines the Dog with sixty-four distinct ; 
 Famed for pre-eminence in envied song, 
 Theme of Homeric and Virgilian lays ; 
 His fierce mouth flames with dreaded Siriits ; 
 Three of his stars retire with feeble beams." 
 
 A-JCOI ILife- to some mythologists, this constellation represents one of Orion's hounds, 
 ttich wah v>lt\ced in the sky, near this celebrated huntsman. Others say it received its 
 (.-.me J n bomT of the dog given by Aurora to Cephalus, which surpassed in speed all the 
 
 110. Situ-tu'c of Sirius? What triangles? 111. Position ana size of Miriam V 
 ther start 7 W'ii"hen? 112. Wesen? What other stars ? Whole number? 
 HISTOUV --ft. 1 ,* xassical description of Canis Major? What different accounts of ite 
 
62 ASTRONOMY. 
 
 animals of Lis species. Cephalus, it is said, attempted to prove this by running him 
 against a fox, which, at that time, was thought to be the fleetest of all a limals. After 
 they had run together a long time, without either of them obtaining the victory, it ia 
 said that Jupiter was so much gratified at the fleetness of the dog, that he assigned him 
 a place in the heavens. 
 
 But the name and form of this constellation are, no doubt, derived from the Egyp- 
 tians, who carefully watched its rising, and by it judged of the swelling of the Nile, 
 which they ca.ied Siris, and, in their hieroglyphical manner of writing, since it was, as 
 it were, the sentinel and watch of the year, represented it under the figure of a dog. 
 They observed that when Sirius became visible in the east, just before the morning dawn, 
 the overflowing of the Nile immediately followed. Thus it warned them, like a faithful 
 dog, to escape from the region of the inundation. 
 
 TELESCOPIC OBJECTS. 
 
 1, a CANIS MAJORIS A brilliant star, with a distant companion ; R. A. Ch. 3Sm. 06s.; 
 i)ec. S. 16 SO' 1. A 1, brilliant white ; B 10, deep yellow, other distant small stars in 
 the field. 
 
 2. 6 CANIS MAJORIS A star with a distant companion in the loins ; R. A. 7h. Olm. 53s. ; 
 Dec, 8- 26* 08' 6". A 3%, light yellow ; B 7^, very pale. Other small stars in the field, 
 A line from Betclguese through $irius intercepts it 12* below the latter star. 
 
 8. CANIS MAJORIS (Adhara) A star with a distant companion in the belly ; R. A 
 6h. 52m. 20s. Dec. S. 28* 45' 5". A 2%, pale orange : B 7, violet. Found by running a 
 - line from the middle of Orion's belt through /3 just west of Sirius, to about 14 beyond 
 the latter star. 
 
 4. A CLUSTER in the back of the head ; R. A. 6h. 52m. 10s. ; Dec. S. 13 29' 2". Tole- 
 rably compressed ; stars of the 8th to llth magnitudes, of which the four principal 
 form the letter Y. 
 
 5. A CLUSTER between Sirius and Monoceros ; R. A. 7h. 10m. 85s. ; Dec. S. 15 21' 4' 
 Stars principally of the 10th magnitude. Discovered by Miss Herschel in 1785. 
 
 CHAPTER V. 
 
 CONSTELLATIONS ON THE MERIDIAN IN MARCH. 
 
 AEGO NAVIS (THE SHIP AEGO). MAP III. 
 
 113. THIS constellation occupies a large space in the southern 
 hemisphere, though but a small part of it can be seen in the 
 United States. It is situated S. E. of Canis Major, and may 
 be known by the stars in the prow and deck of the ship. 
 
 114. If a straight line joining Betelguese and Sirius, be pro- 
 duced 18 to the southeast, it will point out N~aos, a star of the 
 2d magnitude, in the rowlock of the ship. This star is in the 
 S. E. corner of the Egyptian X, and of the large equilateral 
 triangle made by itself with Sirius and the Dove. When on the 
 meridian, it is seen from this latitude about 8 above the south- 
 
 TELESCOPIC OBJECTS. Alpha ? Delta? Epsilon? What clusters ? 
 113. Size and situation of Argo Navis? How kn^wn? H4. How find 2faotj t nud 
 where situated ? IIow high when on the meridian? 
 
AUGO NAVIS. G3 
 
 cm horizon. It comes to the meridian on the 3d of March, 
 about half an hour after Procyon, and continues visible but a 
 few hours. 
 
 115. Gamma, in the middle of the ship, is a star of the 2d 
 magnitude, about 7 S. of Naos, and just skims above the south- 
 ern horizon for a few minutes, and then sinks beneath it. The 
 principal star in this constellation is called, after one of the 
 pilots, Canopus; it is of the 1st magnitude, 36 nearly S. of 
 Sirius, and comes to the meridian 1 7 minutes after it ; but hav- 
 ing about 53 of S. declination, it cannot be seen in the Northern 
 States. The same is true of Miaplacidus, a star of the 1st magni- 
 tude in the oars of the ship, about 25 E. of Canopus, and 61 
 S. of Alphard, in the heart of Hydra. 
 
 An observer in the northern hemisphere, can see the stars as many degrees south of 
 the equinoctial in the southern hemisphere, as his own latitude lacks of 90, and no 
 more. 
 
 116. Markeb, is a star of the 4th magnitude, in the prow of 
 the ship, and may be seen from this latitude 1 6 S. E. of Sirius, 
 and about 10 E. of Wesen, in the back of the Dog. This star 
 may be known by its forming a small triangle with two others 
 of the same magnitude, situated a little above it, on the E., 3 
 and 4 apart. 
 
 117. This constellation contains 64 stars, of which two are 
 ot the 1st magnitude, four of the 2d, and nine of the 3d. Most 
 of these are too low down to be seen in the United States. 
 
 HISTORY. 
 
 This constellation is intended to perpetuate the memory of the famous ship which car- 
 ried Jason and his 54 companions to Colchis, when they resolved upon the perilous 
 expedition of recovering the golden fleece. The derivation of the word A.TQO has been 
 often disputed. Some derive it from Argos, supposing that this was the name of the 
 person who first proposed the expedition, and built the ship. Others maintain that it 
 was built at Argos, whence its name. Cicero calls it Argo, because it carried Grecians^ 
 commonly called Argives. Diodorus derives the word from dp/Of, which signifies swift. 
 Ptolemy says, but not truly, that Hercules built the ship, and called it Argo, after a son 
 of Jason, who bore the same name. This ship had fifty oars, and being thus propelled 
 must have fallen far short of the bulk of the smallest ship craft used by moderns. It is 
 even said that the crew were able to carry it on their backs from the Danube to the 
 Adriatic. 
 
 According to many authors, she had a beam on her prow, cut in the forest of Dodona 
 by Minerva, which had the power of giving oracles to the Argonauts. This ship was the 
 first, it is said, that ever ventured on the sea. After the expedition was finished, and 
 Jason had returned in triumph, he ordered her to be drawn ashore at the isthmus of 
 Corinth, and consecrated to Neptune, the god of the sea. 
 
 Sir Isaac Newton endeavors to settle the period of this expedition at about 30 yeais 
 
 115. Size and situation of Gamma? Name the principal star in this constellation V 
 Its magnitude? Is it ever seen in the U. S. ? What said of Miaplacidus? Remark in 
 fine print? 116. What said of Markeb? How known? 117. Number of stars in 
 Argo Navis? Magnitudes? 
 
 HISTOKT. Design of th : s constellation ? Import of the term A rgof Size and struc- 
 ture of the ship? What myth respecting this ship? What remark respecting Hb 
 Isaac Newton? Dr. Brya it's opinion ? 
 
04 ASTRONOMY. 
 
 before the destruction of Troy, and 43 years after the death of Solomon. Dr. Bryant 
 however, rejects the history of tl^e Argonautic expedition as a mere fiction of the Greeks, 
 and supposes that this group of stars, which the poets denominate Argo Navis, refers to 
 Noah's ark and the deluge, and that the fable of the Argonautic expedition is founded 
 on cei^ain Egyptian traditions that related to the preservation of Is'oah and his family 
 during the flood. 
 
 TELESCOPIC OBJECTS. 
 
 , ARGO NAVIS A star with a distant companion ; R. A. 8h. 00m. 44s. ; Dec. S. 28* 
 BO' 8*. A 3J, pale yellow ; B 10, greyish. Other small stars in the field. 
 
 2. A SMALL GALAXY CLUSTER ; R. A. 7h. 87m. 44s ; Dec. S. 28 29' 1". 
 
 3. A neat DOUBLE STAR over the ship's stern ; R. A. 7h. 38m. 08s. ; Dec. S. 14 18' 8". 
 A 7, silvery white ; B 7 Jg, pale white. 
 
 4. A close DOUBLE STAR over the Argo's stern ; R. A. 7h. 40m. 27s. ; Dec. S. 11* 48' 8" 
 A 7^, pale yellow ; B 9, light blue. 
 
 5. A bright PLANETARY NEBULA ; R. A. 7h. 34m. 46s. ; Dec. S. 17* 50' 2". A fine object, 
 pale bluish white, and may be identified by several small stars in its vicinity. See Map 
 V'JIL, Fig. 37. 
 
 CANCER (THE OEAB). MAP HJ, 
 
 118. Cancer is now the fifth constellation and fourth sign ot 
 the Zodiac. It is situated in the ecliptic, between Leo on the 
 E. and Gemini on the W. It contains 83 stars, of which one is 
 of the 3d, and seven of the 4th magnitude. Some place the first- 
 mentioned star in the same class with the other seven, and con- 
 sider none larger than the 4th magnitude. 
 
 119. Beta is a star of the 3d or 4th magnitude, in the south- 
 western claw, 10 N. E. of Procyon, and may be known from 
 the fact that it stands alone, or at least has no star of the same 
 magnitude near it. It is midway between Procyon and Acubens. 
 
 120. Acubens, is a star of similar brightness, in the south- 
 eastern claw, 10 N. E. of Beta, and nearly in a straight line 
 with it and Procyon. An imaginary line drawn from Capella 
 through Pollux, will point out Acubens, at the distance of 24 p 
 from Pollux. It may be otherwise distinguished by its standing 
 between two very small stars close by it in the same claw. 
 
 121. The southern Asellus, marked Delta, is situated in the 
 line of the ecliptic, and, in connection with Wasat and Tejat, 
 marks the course of the earth's orbit for a space of 36 from 
 the solstitial colure. 
 
 A few degrees S. of Cancer, and about 17 E. of Procyon, are four stars of the 4th 
 magnitude, 3 or 4 apart, which mark the head of Hydra. The rest of this constellation 
 is delineated on Map IV. 
 
 TELESCOPIC OBJECTS. Iota? What cluster? Double stars? Nebula? Point out on 
 the map ? 
 
 IIS. Place of Cancev in the Zodiac? In other respects? Number and size of it' 
 stars? 119. Beta? How known? 120. Acubens? How found? 121. Situation 
 nf Delta, ? Remarks respecting Hydra? Respecting the sign Cancer? 
 
CANCER. 65 
 
 The beginning of the sign Cancer (not the constellation) is called the Tropic of Can- 
 jer, and when the sun arrives at this point, it has reached its utmost limit of north decli- 
 nation, where it seems to remain stationary a few days before it begins to decline again 
 to the south. This stationary attitude of the sun is called the summer solstice; from two 
 Latin words signifying the sun's standing still. The distance from the first point of 
 Cancer to the equinoctial, which, at present, is 23 27%', is called the obliquity of the 
 ecliptic. It is a remarkable and well ascertained fact, that this is continually growing 
 less and less. The tropics are slowly and steadily approaching the equinoctial, at the 
 rate of about half a second every year ; so that the sun does not now come so far north 
 of the f quator in summer, nor decline so far south in winter, as it must have done at the 
 creation, by nearly a degree. 
 
 HISTORY. 
 
 In the Zodiacs of Esne and Dendera, and in most of the astrological remains of Egypt, 
 n Scairabaeus, or Beetle, is used as the symbol of this sign ; but in Sir William Jones' 
 Oriental Zodiac, and in some others found in India, we meet with the figure of a crab. 
 As the Hindoos, in all probability, deriw. J their knowledge of the stars from the Chal- 
 deans, it is supposed that the figure of the crab, in this place, is more ancient than the 
 Beetle. 
 
 In some ea stern representations of this sign, two animals, like asses, are found in this 
 division of L.e Zodiac; and as the Chaldaic name for the ass may be translated muddi- 
 ness, it is supposed to allude to the discoloring of the Nile, which river was rising when 
 the sun ente-ed Cancer. The Greeks, in copying this sign, have placed two asses as the 
 appropriate symbol of it, which stal remain. They explain their reason, however, for 
 adopting this^gure, by saying that these are the animals that assisted Jupiter in hia 
 victory over the giants. 
 
 Dopuis accounts for the origin of the asses in the following words : " Le Cancer oil 
 sont les etoiles appellees les anes, forme 1'empreinte du pavilion d' Issachar que Jacob 
 assimile a 1'ane." 
 
 Mytholog'sts give different accounts of the origin of this constellation. The prevail- 
 ing opinion ,s, that while Hercules was engaged in his famous contest with the dreadful 
 Lernsean monster, Juno, envious of the fame of his achievements, sent a sea-crab to 
 bite and an icy the hero's feet, but the crab being soon dispatched, the goddess, to reward 
 its services, placed it among the constellations. 
 
 " The Scorpion's claws here clasp a wide extent, 
 And here the Crab's in lesser clasps are bent." 
 
 TELESCOPIC OBJECTS. 
 
 1. d CANCRI A very delicate DOUBLE STAR, under the Crab's mouth ; R. A. 8h. 35m. 
 5s. ; Dec. 1. 18 44' 04". A 4J^, straw color ; B 15 blue, only seen by glimpses. 
 
 2. CANCRI A star with a distant companion, on the Crab's body ; R. A. 8h. 31m. 
 16s.; Dec. N. 20 06' 02'. A 6%, and B 7, both pale white ; and a third star in the field 
 of nearly Uie same magnitude. 
 
 3. (, CANCRI A fine TRIPLE STAR, just below the after claws of the Crab; R. A. 8h. 03m. 
 02s.; Dec. N. 18 07' 05". A 6, yellow; B 7, orange tinge; C 7%, yellowish. Supposed 
 to be a Ternary system. 
 
 4. Abort 7" northeasterly from Tegmine, is a nebulous cluster of very minute stars, in 
 the crest of Cancer, sufficiently luminous to be seen by the naked eye. It is situated in 
 a triangular position with regard to the head of the Twins and the Little Dog. It is about 
 20 W. of ^ach. It may otherwise be discovered by means of two conspicuous stars of 
 the 4th magnitude, lying one on either side of it, at the distance of about 2, called the 
 northern and southern Aselli. Bj some of the Orientalists, this cluster was denominated 
 Prcesepe, .he Manger, a contrivance which their fancy filled up for the accommodation 
 cf the Aselli or Asses; and it is so called by modern astronomers. The appearance of 
 this group to the unassisted eye, is not unlike the nucleus of a comet, and it was repeat- 
 edly mistaken for the comet of 1832, which, in the month of November, passed in its 
 neighborhood. Map VIII., Fig. 38. 
 
 5. A P-CH BUT LOOSE CLUSTER in the Crab's southern claw, where a line from Rigel 
 through Procyon, into the east-northeast, will find it about 5 north of e in the Hyades ; 
 R. A. 8h. 42m. 26s. ; Dec. N. 12 23' 06". Stars mostly of the 9th and 10th magnitudes. 
 See Map VIII., Fig. 39. 
 
 HISTO-.*. What other figures for Cancer? Egyptian? Hindoo? Greek? Oriein oJ 
 this cor 'ellation? 
 TELESCOPIC OBJECTS. Delta ? Ef silon ? Ze\a ? What Clusters ? Point out on the Mar 
 
66 ASTRONOMY. 
 
 CHAPTER VI. 
 
 CONSTELLATIONS ON THE MERIDIAN IN APRIL. 
 
 LEO (THE LION). MAP IV. 
 
 122. LEO is one of the most brilliant constellations in the 
 winter hemisphere, and contains an unusual number of very 
 bright stars. It is situated* next E. of Cancer, and directly S. 
 of Leo Minor and the Great Bear. 
 
 The Hindoo astronomer, Varaha, says, " Certainly the southern solstice was once in 
 the middle of Asleha (Leo) ; the northern in the first degree of Dhanishta" (Aquarius). 
 Since that time, the solstitial, as well as the equinoctial points, have gone backward on 
 the ecliptic 75. This divided by 50%", gives 5373 years ; which carry us back to the 
 year of the world 464. Sir W. Jones says, that Varaha lived when the solstices were in 
 the first degrees of Cancer and Capricorn ; or about 400 years before the Clyistian era. 
 
 123. Leo is the fifth sign, and the sixth constellation of the 
 Zodiac. The mean right ascension of this extensive group is 
 150, or 10 hours. Its center is therefore on the meridian the 
 sixth of April. Its western outline, however, comes to the 
 meridian on the 18th of March, while its eastern limit does not 
 reach it before the 3d of May. 
 
 This constellation contains 95 visible stars, of which one is 
 of the 1st magnitude, one of the 2d, six of the 3d, and fifteen of 
 the 4th. 
 
 " One splendid star of highest dignity, 
 One of the second class the Lion boasts, 
 And justly figures the fierce summer's rage." 
 
 124. The principal star in this constellation is of the 1st mag- 
 nitude, situated in the breast of the animal, and named Regulus, 
 from the illustrious Roman consul of that name. 
 
 It is situated almost exactly in the ecliptic, and may be 
 readily distinguished on account of its superior brilliancy. It is 
 the largest and lowest of a group of five or six bright stars 
 which form a figure somewhat resembling a sickle, in the neck 
 and shoulder of the Lion. There is a little star of the 5th mag- 
 nitude, about 2 S. of it, and one of the 3d magnitude 5 N. of 
 it, which will serve to point it out. 
 
 Great use is made of Regulus by nautical men, for determining their longitude at sea. 
 Its latitude, or distance from the ecliptic, is less than j; but its declination, or dis- 
 tance from the equinoctial, is nearly 13 N. ; so that its meridian altitude will be just 
 
 122. Describe Leo. Its situation ? What remarkable statement of Varaha? Calcula- 
 tions upon it? 123. Position of Leo in the Zodiac ? When on the meridian? Number 
 and size of its stars ? 124. Its principal star? Situation? How distinguished? What 
 ijse made of Regulus ? When on the meridian, where are Castor and Pollux ? 
 
LEO. 67 
 
 equal to that of the sun on the 19th of August. Its right ascension is very nearly 150*. 
 It therefore culminates about 9 o'clock on the 6th of April. 
 
 When Regulus is on the meridian, Castor and Pollux are seen about 40 N. W. of it, 
 and the two stars in the Little Dog are about the same distance in a S. W. direction ; 
 with which, and the two former, it makes a large isosceles triangle whose vertex is at 
 Hegulua. 
 
 125. The next considerable star is 5 N. of Regulus, marked 
 Eta, situated in the collar ; it is of between the 3d and 4th 
 magnitudes, and with Regulus constitutes the handle of the 
 sickle. Those three or four stars of the 3d magnitude, N. and 
 W. of Eta, arching round with the neck of the animal, describe 
 the blade. 
 
 126. Al Gieba is a bright star of the 2d magnitude, situated 
 in the shoulder, 4 in a N. E. direction from Eta, and may be 
 easily distinguished by its being the brightest and middle one of 
 the three stars lying in a semicircular form curving toward the 
 west ; and it is the first in the blade of the sickle. 
 
 12T. Adhafera is a star of the 3d magnitude, situated in the 
 neck, 4 N. of Al Gieba, and may be known by a very minute 
 star just below it. This is the second star in the blade of the 
 sickle. 
 
 128. Ras al Asad, situated before the ear, is a star of the 3d 
 or 4th magnitude, 6 W. of Adhafera, and is the third in the 
 blade of the sickle. The next star, Epsilon, of the same magni- 
 tude, situated in the head, is 2 S. W. of Ras al Asad, and a 
 little within the curve of the sickle. About midway between 
 these, and a little to the E., is a very small star hardly visible 
 to the naked eye. 
 
 129. Lambda, situated in the mouth, is a star of the 4th 
 magnitude, 3 S. W. of Epsilon, and the last in the sickle's 
 point. Kappa, situated in the nose, is another star of the same 
 magnitude, and about as far from Lambda as Epsilon. Epsilon 
 and Kappa are about 4^- apart, and form the longest side of a 
 triangle, whose vertex is in Kappa. 
 
 130. Zozma, situated in the back of the Lion, is a star of the 
 3d magnitude 18 N. E. of Regulus, and midway between it and 
 Coma Berenices, a fine cluster of small stars, 18 N. E. of 
 Zozma. 
 
 131. Theta, situated in the thigh, is another star of the 3d 
 magnitude, 5 directly S. of Zozma, and so nearly on the same 
 meridian that it culminates but one minute after it. This star 
 
 125. Next principal star size and position? 126. Al Gieba? How known? 
 
 12T. Adhafera? 128. Ras al Asad? Epsilon? 129. Situation and size of Lambda* 
 
 Of Kappa? 180. Of Zo/ma? 181. Of Theta? What triangle? What other stars 
 mentioned? 
 
b8 ASTRONOMY. 
 
 makes a right-angled triangle, with Zozma on the N. and Dene- 
 bola on the E., the right angle being at Theta. 
 
 Nearly in a straight line with Zozma and Theta, and sonth 
 of them, are three or four smaller stars, 4 or 5 apart, which 
 mark one of the legs. 
 
 132. Dentbola is a bright star of the first magnitude, in the 
 brush of the tail, 10 S. E. of Zozma, and may. be distinguished 
 by its great brilliancy. It is 5 W. of the equinoctial colure, 
 and comes to the meridian 1 hour and 41 minutes after Regulus, 
 on the 3d of May ; when its meridian altitude is the same as 
 the sun's at 12 o'clock the next day. 
 
 When Denebola is on the meridian, Regulus is seen 25" W. of it, and Phad, in the 
 square of Ursa Major, bears 39 N. of it. It forms, with these two, a large right-angled 
 triangle ; the right angle being at Denebola. It is so nearly on the same meridian with 
 Phad that it culminates only four minutes before it. 
 
 Denebola is 35V W. of Arcturus, and about the same distance N. W. of Spica Vir- 
 ginis, and forms, with them, a large equilateral triangle on the S. E. It also forms with 
 Arcturus and Cor Caroli a similar figure, nearly as large on the N. E. These two 
 triangles, being joined at their base, constitute a perfect geometrical figure of the form 
 of a Rhombus, called by some, the DIAMOND OF VIRGO. 
 
 A line drawn from Denebola through Regulus, and continued 7* or 8 further in the 
 same direction, will point out Xi and Omicron, of the 3d and 4th magnitudes, situated 
 in the foreclaws, and about 3 apart. 
 
 There are a number of other stars of the 3d and 4th magnitudes in this constellation, 
 which require no description, as the scholar will easily trace them out from the map. 
 The position of Regulus and Denebola are often referred to in the geography of the 
 heavens, as they serve to point out other clusters in the same neighborhood. 
 
 HISTORY. 
 
 According to Greek fable, this Lion represents the formidable animal which infested 
 the forests of Nemaea. It was slain by Hercules, and placed by Jupiter among the stars 
 in commemoration of the dreadful conflict. Some writers have applied the story of the 
 twelve labors of Hercules to the progress of the sun through the twelve signs of the 
 ecliptic ; and as the combat of that celebrated hero with the Lion was his first labor, 
 they have placed Leo as the first sign. The figure of the Lion was, however, on the 
 Egyptian charts long before the invention of the fables of Hercules. It would seem, 
 moreover, according to the fable itself, that Hercules, who represented the sun, actually 
 slew the Nemaean Lion, because Leo was already a zodiacal sign. 
 
 In hieroglyphical writing the Lion was an emblem of violence and fury; and the 
 representation of this animal in the Zodiac, signified the intense heat occasioned by the 
 sun when it entered that part of the ecliptic. The Egyptians were much annoyed by 
 lions during the heat of summer, as they at that season left the desert, and haunted the 
 banks of the Nile, which had then reached its greatest elevation. It was therefore 
 natural for their astronomers to place the Lion where we find him in the Zodiac. 
 
 The figure of Leo, very much as we now have it, is in all the Indian and Egyptian 
 Zodiacs. The overflowing of the Nile, which was regularly and anxiously expected every 
 year by the Egyptians, took place when the sun was in this sign. They therefore paid 
 more attention to it, it is to be presumed, than to any other. This was the principal 
 reason, Mr. Green supposes, why Leo stands first in the zodiacs of Dendera. 
 
 In the Hebrew Zodiac, Leo is assigned to Judah, on whose standard, according to rJ. 
 traditions, a Lion is painted. This is clearly intimated in numerous passages of the 
 Hebrew writings : Ex. " Judah is a Lion's whelp ; he stooped down, he couched as a 
 
 132. Size and position of Denebola? How known ? When does it come to the meri- 
 dian as compared with Regulus? What said of its meridian altitude? When on the 
 meridian where is Regulus seen? Phad? What triangle? How is Denebolo situated 
 with respect to Arcturus and Spica Virginis ? To Cor Caroli ? What other large figures 
 
 HISTORY. Greek fable? Egyptian? Hebrew Zodiacs? Scripture allusions to thf 
 t-'cn? 
 
LEO MINOR. 69 
 
 L!on, and as an Old Lion ; who shall rouse him up ?" Gen. xlix. 9. " The Lion of the 
 tribo of Judah hath prevailed." Rev. v. 5. 
 
 TELESCOPIC OBJECTS 
 
 I. a LEONIS (Rtguliu) A bright star with a distant companion ; R. A. 9h. 59m. 51a. ; 
 Dec. N. 12* 44' 08". A 1, flushed white ; B 8%, pale purple. 
 
 2 8 LEONIS (Denebola}^ fine star with a distant companion ; R. A. lib. 40m. 54s. j 
 Dc. N. 15 28' 0". A 2^, bluish ; B 8, dull red. 
 
 8. y LEONfs(^ Gieba)A. splendid DOUBLE STAB; R. A. lOh. llm. 08s.; Dec. N. 20 
 89' 0". A 2, bright orange; B 4, greenish yellow. A most beautiful object binary- 
 period supposed about 1000 years. Map V1IL, Fig. 6. 
 
 4. 6 LEONIS (Zozma)A. coarse TRIPLE STAB; R. A. llh. 05m. 35s. ; Dec. N. 21 24' 1*. 
 A 3, pale yellow ; B 13, blue ; C 9, violet. 
 
 5. e LEONIS A star with a distant companion in the mouth of Leo ; R. A. 9h. 30m. 46s ; 
 Dec. N. 24 30' 5". A 3, yellow ; B 10, pale grey. 
 
 6. i LEONIS A BINARY STAR in the flank, 7 S. W. of Denebola (F on map;; R. A. llh. 
 15m. 85s. ; Dec. N. 11* 24' 8". It forms a neat scalene triangle with (3 and &. A 4, pale 
 yellow ; B 7 % , light blue ; a beautiful object. 
 
 7. /j, LEONIS (Bas Al Asad)A DOUBLE STAB ; R. A. 9h. 43m. 89s. ; Dec. N. 26* 46' 5'. 
 A 3, orivnge ; B 10, pale lilac. 
 
 8. A neat DOUBLE STAR near Zozma ; R. A. llh. 05m. 17s. ; Dec. 21 00' 8'. Components 
 both 7J6, and both faint yellow; a beautiful object. 
 
 9. A BRIGHT NEBULA near the hind paws ; R. A. lOh. 57m. 37s. ; Dec. N. 49' 6". Large, 
 elongated, well-defined an enormous mass of luminous matter one of a vast number 
 of spherical nebulae in the vicinity. 
 
 10. A bicentral WHITE NEBULA in the lower jaw, 2" south of /I Leonis ; R. A. 9h. 23m. 
 07s. ; Dec. N. 22 1 2' 1". May be classed as double small stars in field ; difficult object. 
 See Map VIII., Fig. 40. 
 
 II. A lucid WHITE NEBULA on the Lion's ribs, about 9" due east of Regulus ; R. A. lOh. 
 35m. 81s. ; Dec. N. 12 31' 9". Round and bright, with two small stars in field. Another 
 large pale white nebula, about 1 east of it. 
 
 12. A PAIR OP BRIGHT CLASS NEBULA in the Lion's belly ; R. A. lOh. 39m. 49s. ; Dec. N. 
 13 28'. Found south of line joining Regulus and $ Leonis, about 10" east of, and 
 nearly on a parallel with the latter. 
 
 13. A LARGE, ELONGATED NEBULA, with a bright nucleus on the Lion's haunch; R. A. 
 llh. llm. 48s. ; Dec. N. 13" 52' 4" ; just 3" southeast of #, with another smaller nebula, 
 and several stars in the field. Map VIII., Fig. 41. 
 
 LEO MINOR (THE LITTLE LION). MAP IY. 
 
 133. Leo Minor contains 53 stars, including only one of thu 
 3d magnitude, and five of the 4th. The principal star is situated 
 in the body of the animal, 13 N. 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 N. W. 
 
 It forms an equilateral triangle with Gamma and Delta Leonis, the vertex being in 
 Leo Minor. This star is marked with the letter I, in modern catalogues, and being the 
 principal representative of the constellation, 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 magnitude, in the 
 first hind paw. 
 
 " The Smaller Lion now succeeds ; a cohort 
 Of fifty stars attend his steps ; 
 And three, to sight unarm'd, invisibl .'' 
 
 TELESCOPIC OBJECTS. Alpha ? Beta? Gamma? -Point out on the map. Dclti? 
 Epoilou? Iota? Mu? What nebulae? Which shown on the map ? Point out. 
 183. Describe Leo Minor ? Its principal star ? Helps form what triangle ? 
 
70 ASTRONOMY. 
 
 134. This constellation was formed by Hevelius, out ol the 
 Stella informes, or unformed stars of the ancients, which lay 
 scattered between the Zodiacal constellation Leo on the S., and 
 Ursa Major on the N. 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, or those which have been added to our celestial maps 
 B'nce 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. 
 
 TELESCOPIC OBJECTS. 
 
 A BRIGHT OVAL NEBULA between Lynx and Cancer, but given to Leo Minor ; R. A. 8h. 
 42m. 44s. ; Dec. N. 34 00' 6". Direct telescope 16 north by east of Presepe in Cancer 
 
 SEXTANS (THE SEXTANT). MAP IV. 
 
 135. Sextans contains 41 very small stars, including only one 
 as large as the 4th magnitude. This is situated very near the 
 equinoctial, 1 3 S. of Regulus, and comes to the meridian about 
 the same time on the 6th of April. The other stars in this con- 
 stellation are too small to engage attention. A few of the 
 largest of them may be traced out from the map. 
 
 The SEXTANT, called also URANIA'S SEXTANT, is a modern constellation that Hevelius 
 made out of the unformed stars of the ancients, which lay scattered between the Lion 
 on the N., and Hydra on the S. 
 
 Urania was one of the muses, and daughter of Jupiter and Mnemosyne. She pre- 
 sided over astronomy. She was represented as a young virgin, dressed in an azure- 
 colored robe, crowned with stars, holding a robe in her hands, and having many mathe- 
 matical instruments about her. 
 
 A sextant, in mathematics, is the sixth part of a circle, or an arc comprehending 60 
 degrees. But the term is more particularly used to denote an astronomical instrument 
 well known to mariners. Its use is the same as that of the quadrant: namely, to mea- 
 sure the angular distance, and take the altitude of the suri, moon, planets, and fixed 
 stars. It is indispensable to the mariner in finding the latitude and longitude at sea, 
 and should be in the hands of every surveyor and practical engineer. It may serve the 
 purpose of a theodolite, in measuring inaccessible heights and distances. It may gra- 
 tify the young pupil to know, that by means of such an instrument, well adjusted, and 
 with a clear eye and a steady hand, he could readily tell, within a few hundred yards 
 how far north or south of the equator he was, and that from any quarter of the world, 
 known or unknown. This constellation is BO called, on account of a supposed resem- 
 blance to this instrument. 
 
 TELESCOPIC OBJECTS. 
 
 1. A DOUBLE STAR on the right fore leg of Leo, though crimped into the sextant ; R. A 
 9h. 45m. 45s. ; Dec. N. 5 41' S". It lies about one-third of the way from Regulus to 
 Alphard. A 7, and B. 9, both blue, and well-defined. 
 
 134. Origin of Leo Minor? Mean R. A.? What remark respecting the notation of 
 ihe stars ? 
 
 TELESCOPIC OBJECTS. What nebula? Situation? How find? 
 
 135. Describe Sextans ? Situation of its principal star ? What said of the remainder ? 
 What said of the age of this constellation ? Of Urania ? Of the Sextant as a nautical 
 instrument? . 
 
 TELESCOPIC OBJECTS. What double stars? What nebula? What *x.nnrkable sigh 4 
 seen near this nebula! 
 
HYDRA. 71 
 
 2. A neat DOUBLE STAR on the north extreme of the graduated limb of the instrument; 
 nnd three-fifths of the distance oetween Alphard and Denebola ; R. A. lOh. 35m. 02s.; 
 Dec. N. 5 85' 2". A 7, topaz yellow; B 8, smalt blue ; a fine object. 
 
 8. A bright class ROUND NEBULA on the frame of the instrument ; R. A. lOh. 05m. 68s.; 
 Dec. N. 4 15' 1". A good telescope shows another large but faint nebula near by. 
 
 This object is on or near the spot where the Capuchin, De Rheita, fancied he saw th 
 napkin of St. Veronica, in 1783. Captain Smyth has a picture of this wonderful napkin ; 
 and Sir J. Herschel remarks that " many strange things were seen among the stars 
 Deforo the use of powerful telescopes became common." 
 
 HYDRA AND THE CUP. MAP IY. 
 
 136. HYDRA, (the Water- Serpent,} is an extensive constella- 
 tion, winding from E. to W. in a serpentine direction, over a 
 space of more than 100. degrees in length. It lies south of 
 Cancer, Leo and Yirgo, and reaches almost from Canis Minor 
 to Libra. It contains sixty stars, including one of the 2d mag- 
 nitude, three of the 3d, and twelve of the 4th. 
 
 137. Alphard or Cor Hydra, in the heart, is a lone star of 
 the 2d magnitude, 23 S. S. W. of Regulus, and comes to the 
 meridian at the same time with Lambda, in the point of the 
 sickle, about 20 minutes before 9 o'clock on the 1st of April. 
 There is no other considerable star near it, for which it can be 
 mistaken. An imaginary line drawn from Gamma Leonis 
 through Kegulus, will point out Cor Hydrse, at the distance 
 of 23. 
 
 138. The head of Hydra may be distinguished by means of 
 four stars of the 4th magnitude, 2^- and 4 apart, situated 6 
 S. of Acubens, and forming a rhomboidal figure. The three 
 upper stars in this cluster form a small arch, and may be known 
 by two very small stars just below the middle one, making with 
 it a very small triangle. The three western stars in the head 
 also make a beautiful little triangle. The eastern star in this 
 group, marked *Zeta, is about 6 directly S. of Acubens, and 
 culminates at the same time. 
 
 139. When Alphard is on the meridian, Alkes, of the 4th mag- 
 nitude, situated in the bottom of the Cup, may be seen 24 S. E. 
 of it, and is distinguished by its forming an equilateral triangle 
 with Beta and Gamma, stars of the same magnitude, 6 S. and 
 E. of it. Alkes is common both to Hydra and the Cup. Beta, 
 on the S., is in Hydra, and Gamma, on the N. E., is near the 
 middle of the Cup. A line drawn from Zozma, through Theta 
 
 136. Describe Hydra? Its situation ? Number and magnitude of its stars? 187. Po- 
 situ n and magnitude of Alphard ? How pointed out? 138. How i the head of Hydra 
 distinguished? 139. What said of Alkes? Of Beta and Gamma? Hor is Beta 
 found ? 
 
Y2 ASTRONOMY. 
 
 Leoiiis, and continued 38J directly S. will reach Beta ; it is 
 therefore on the same meridian, and will culminate at the saino 
 time on the 23d of April. 
 
 140. The Cup itself (called also the Crater], may be easily 
 distinguished by means of six stars of the 4th magnitude, form- 
 ing a beautiful crescent, or semicircle , opening to the W. The 
 center of tbis group is about 15 below the equinoctial, and 
 directly S. of the hinder feet of Leo. The crescent form of the 
 stars in the Cup is so striking and well defined, when the moon 
 is absent, that no other description is necessary to point them 
 out. Its center comes to the meridian about two hours after 
 Alphard, on the same evening ; and consequently, it culminates 
 at 9 o'clock, one month after Alphard does. The remainder of 
 the stars in this constellation may be easily traced by aid of 
 the map. 
 
 141. When the head of Hydra is on the meridian, its other 
 extremity is many degrees below the horizon, so that its whole 
 length cannot be traced out in the heavens until its center, or 
 the Cup, is on the meridian. 
 
 " Near the equator rolls 
 
 The sparkling Hydra, proudly eminent 
 To drink the Galaxy's refulgent sea; 
 Nearly a fourth of the encircling curve 
 Which girds the ecliptic, his \ast folds involve; 
 Yet ten the number ol his stars diffused 
 O'er the long track of his enormous spires ; 
 Chief beams his heart, sure of the second rank, 
 But emulous to gain the first." Eudonia. 
 
 HISTORY. 
 
 ihe astrologers of the east, in dividing the celestial hosts into various compartments, 
 assigned a popular and allegorical meaning to each. Thus the sign Leo, which passee 
 the meridian about midnight, when the sun is in Pisces, was called the House of tht, 
 Lions, Leo being the domicil of Sol. 
 
 The introduction of two serpents into the constellations of the ancients, had its origin 
 it is supposed, in the circumstances that the polar one represented the oblique course of 
 the stars, while the Hydra, or Great Snake, in the southern hemisphere, symbolized the 
 moon's course ; hence the Nodes are called the Dragon's head and tail to this day, 
 
 The hydra was a terrible monster, which, according to mythologists, infested tin 
 neighborhood of the lake Lerna, in the Peloponnesus. It had a hundred heads, accord- 
 Ing to Diodorous ; fifty, according to Simonides ; and nine, according to the more com 
 monly received opinion of Apollodorus, Hyginus, and others. As soon as one of these 
 heads was cut off, two immediately grew up if the wound was not stopped by fire. 
 
 " Art thou proportion'd to the hydra's length, 
 Who by his wounds received augmented strength? 
 He raised a hundred hissing heads in air, 
 When one I lopp'd, up sprang a dreadful pair." 
 
 To destroy this dreadful'monster, was one of the labors of Hercules, and this he easily 
 effected with the assistance of lolaus, who applied a burning iron to the wounds as 
 soon as one head was cut off. While Hercules was destroying the hydra, Juno, jealous of 
 lis glory, sent a sea-crab to bite his foot. This new enemy was soon despatched ; an 1 
 
 140. How is the Gup distinguished ? Is it easily found ? 141. What id said of the 
 jmnt of Hydra east and west? History of Hydra ? 
 
URSA MAJOR. 78 
 
 Juno was unable to succeed in her attempts to lessen the fame of Hercules. The con* 
 queror dipped his arrows in the gall of the Hydra, which ever after rendered the wounds 
 Inflicted with them incurable and mortal. 
 
 This fable of the many-headed hydra may be understood to mean nothing more than 
 that the marshes of Lerna were infested with a multitude of serpents, which seemed to 
 multiply as fast as they were destroyed, 
 
 TELESCOPIC OBJECTS. 
 
 \. a SRATERIS A star with two very distant companions in the base of the cup ; R. A. 
 tOh. 52m. OOs ; Dec. S. 17 26' 9". A. 4, orange tint; B 8, intense blood color ; C 9, p.-ile 
 Hue. 
 
 2. y CRATERIS A close DOUBLE STAR, in the center of the cup ; R. A. llh. 16m. 54s. ; 
 Dec. S. 16 48' 3"; A 4, bright white ; B 14, grey , with a star of the llth magnitude fol- 
 lowing, on a line with A. B. 25' distant. 
 
 3. 6 CRATERIS A star with a very distant companion, on the cup, midway between 
 Alphard and Spica, but a little south of the line joining them; R. A. llh. llm. 21s.; 
 Dec. S. 13 54' 8". A 3^, pale orange ; B 11, pale blue other small stars in the field. 
 
 4. a HYDRJS (Cor Hydrce,)K bright star in the heart of Hydra with a distant com- 
 panion ; R. A. .th. 19m. 44s. ; Dec. S. 7 58' 1". A 2, orange tint; B 10, pale green. 
 
 5. <5 HYDR.E A star with a distant companion in the head of Hydra; R. A. 8h. 29m. 
 14s. ; Dec. N. 6" 15' 5". A 4, light topaz ; B 9, livid several other stars in the field. 
 
 6. e HYDRJS A double star in the head ; R. A. 8h. 38m. 18s. ; Dec. N. 7 00' 2'. A 4, 
 pale yellow; B 8J6, purple. 
 
 7. A PLANETARY NEBULA in the middle of the body; R. A. lOh. 17m. Ols. ; Dec. S. II* 
 50' 6"; greyish white. 
 
 CHAPTER VII. 
 
 CONSTELLATIONS ON THE MERIDIAN IN MAY. 
 
 UKSA MAJOR (THE GREAT BEAR). MAPS IV. AND VI. 
 
 142. URSA MAJOR is situated between Ursa Minor on the north, 
 and Leo Minor on the south. It is one of the most noted and 
 conspicuous in the northern hemisphere. It has been an object 
 of universal observation in all ages of the world. 
 
 The priests of Belus and the Magi of Persia, the shepherds of Chaldea, and the Phoa- 
 nician navigators, seem to have been equally struck with its peculiar outlines. And i{ 
 is somewhat remarkable, that a remote nation of American Aborigines, the Iroquois, 
 and the earliest Arabs of Asia, should have given to the very same constellation the 
 name of " Great Bear," when there had probably never been any communication 
 between them; and when the name itself is so perfectly arbitrary, there being no resem- 
 blance whatever to a bear, or to any other animal. 
 
 143. It is readily distinguished from all others oy means of a 
 remarkable cluster of seven bright stars, forming what is fami- 
 liarly termed the Dipper, or Ladle. In some parts of England 
 it is called " Charles' Wain," or wagon, from its fancied resem- 
 
 TKLKSCOPIO OBJECTS. Alpha? Gamma? Delta? Alpha Hydrae? Delta Hydras? 
 Eta Hydra ? What Nebula ? 
 
 'i42. Describe Ursa Major? What remarkable fact as to its name? 148. How dis- 
 tinguished? What other names for the Dipper ? What remark in small type ? 
 
74 ASTRONOMY. 
 
 r 
 
 blance to a wagon drawn by three horses in a line. Others call 
 ifc the Plough. The cluster, however, is more frequently put foi 
 the whole constellation, and called simply the Great Bear. 
 
 We see no reason to reject the very appropriate appellation of the shepherds, for the 
 resemblance is certainly in favor of the Dipper ; the four stars in the square forming the 
 bowl, and the other three the handle. 
 
 144. When the Dipper is on the meridian, above the pole, the 
 bottom lies toward us, with the handle on the right. 
 
 Beiwtnascfi is a bright star of the 2d magnitude, and is the 
 first in the handle. The second, or middle star in the handle is 
 Mizar, T distant from Benetnasch. It may be known by means 
 of a very minute star almost touching it, called Alcor. 
 
 145. The third star in the handle is called Alioth, and is about 
 4^- W. of Mizar. Alioth is very nearly opposite Shedir in Cas- 
 siopeia, and at an equal distance from the pole. Benetnasch, 
 Mizar, and Alioth constitute the handle, while the next four in 
 the square form the bowl of the Dipper. 
 
 146. Five and a half degrees W. of Alioth is the first star in 
 the top of the Dipper, at the junction of the handle, called 
 Megrez ; it is the smallest and middle one of the cluster, and is 
 used in various observations both on sea and land for important 
 purposes. 
 
 When Megrez and Caph have the same altitude, and are seen in the same horizontal 
 line east and west, the polar star is then at its greatest elongation from the true pole of 
 the heavens ; and this is the proper time for an observer to take its angle of elevation, 
 in order to determine the latitude, and its azimuth or angle of declination, in order to 
 determine the magnetic variation. 
 
 147. At the distance of 4 S. W. of Megrez is Phad, the 
 first star in that part of the bottom which is next the handle. 
 
 The stars in this cluster are so well known, and may be so easily described without 
 reference to their relative bearings, that they would rather confuse than assist the 
 student, were they given with ever so much accuracy. The several bearings for this 
 cluster were taken when Megrez was on the meridian, and will not apply at any other 
 time, though their respective distances, will remain the same. 
 
 148. At the distance of 8 W. of Phad, is the westernmost 
 star in the bottom of the Dipper called Merak. The bright star 
 5 N. of it, toward the pole, is called Dubhe. These two, are. 
 by common consent, called the Pointers, because they always 
 point toward the pole ; for, let the line which joins them be con- 
 tinued in the same direction 28 J further, it will just reach the 
 north pole. 
 
 The names, positions, and relative distances of the stars in this cluster should be well 
 
 144. How is the handle of the Dipper situated, when the Dipper is above the pole? 
 Describe Benetnasch? Mizar? How known? 145. Alioth? Megrez? Remar* 
 respecting? Phad? Remark in small print? 148. Merak and Dubhe? Constitute 
 what? Remark respecting the names, positions and distances of the stars in Crsa 
 Mujorf Why should these distances be well understood? 
 
URSA MAJOR. 75 
 
 remembered, as they will be frequently adverted to. The distance of Dubht, or tho 
 Pointer nearest to the north pole, is 28 ; -'4*. The distance between the two upper stars iu 
 the Dipper is 10; between the two lower ones is 8; the distance from the brim to the 
 bottom next the handle, is 4>t; between Megrez and Alioth, is 5J$ ; between Alioth 
 and Mizar, 4%; and between Mizar and Benetnasch, 7. 
 
 The reason why it is important to have these distances clearly settled in the mind is, 
 that these stars, being always in view, and more familiar than any other, the student 
 will never fail to have a standard measure before him, which the eye can easily make 
 use of in determining the distances between other stars. 
 
 149. The position of Megrez in Ursa Major, and of Caph in 
 Cassiopeia, is somewhat remarkable. They are both in the equi- 
 noctial colure, almost exactly opposite each other, and equally 
 distant from the pole. Caph is in the colure, which passes 
 through the vernal equinox, and Megrez is in that which passes 
 through the autumnal equinox. The latter passes the meridian 
 at 9 o'clock, on the 10th of May, and the former just six months 
 afterward, at the same hour, on the 10th of November. 
 
 150. Psi, in the left leg of Ursa Major, is a star of the 4th 
 magnitude, in a line with Megrez and Fhad, distant from the 
 latter 12|. A little out of the same line, 3 farther, is another 
 star of the 4th magnitude, marked Epsilon, which may be dis- 
 tinguished from Psi, from its forming a straight line with the two 
 Pointers. 
 
 151. The right fore-paw, and the two hinder ones, each about 
 15 from the other, are severally distinguished by two stars of 
 the 4th magnitude, between 1 and 2 apart. These three 
 duplicate stars are nearly in a right line, 20 S. of, and in a 
 direction nearly parallel with Phad and Dubhe, and are the only 
 stars in this constellation that ever set in this latitude. 
 
 There are a few other stars of equal brightness with those just described, but amidst 
 the more splendid and interesting group with which they are clustered, they seldom 
 engage our observation. 
 
 The whole number of visible stars in this constellation is S7 ; of which five are of tho 
 2d, two of the 3d, and about twice as many of the 4th magnitude. 
 
 HISTORY. 
 
 URSA MAJOR is said to be Calisto, or Helice, daughter of Lycaon, king of Arcadia. She 
 was an attendant of Diana, and mother of Areas, by Jupiter, who placed her among the 
 constellations, after the jealousy of Juno had changed her into a bear. 
 
 " This said, her hand within her hair she wound, 
 Swung her to earth, and dragg'd her on the ground; 
 The prostrare wretch ii;ts up her hand in prayer; 
 Her arms grow shaggy, and deform'd with hair, 
 Her nails are sharpen'd into pointed claws, 
 Her hands bear half her weight, and turn to paws; 
 Her lips, that once could tempt a god, begin 
 To grow distorted in an ugiy grin ; 
 
 149. What said of Megrez and Caph? 150. Of Psi and Epsilon? 151. How QuJ 
 the/?^ of the figure? Number of stars in Ursa Major? Magnitudes? 
 
 HHTOHY. Who was Ursa M;ijor before she became a bear? What other supposition 
 How are the two bears represented by the I^yptians? What further remarks V 
 
 B.G. 4 
 
76 ASTRONOMY. 
 
 And lest the supplicating brute might reach 
 The ears of Jove, she was deprived of speech. 
 ******* 
 
 How did she fear to lodge in woods alone, 
 
 And haunt the fields and meadows, once her own ! 
 
 How often would the deep-mouth'd dogs pursue, 
 
 Whilst from her hounds the frighted hunters flew." Ovid's Met. 
 
 ome suppose that her son Areas, otherwise called Bootes, was changed into Ursa 
 Minor, or the Little Bear. It is well known, that the ancients represented both thes" 
 constellations under the figure of a wagon drawn by a team of horses ; hence the appel 
 lution of Charles' Wain, or wagon. This is alluded to in the Phenomena of Aratus, a 
 Greek poem, from which St. Paul quotes in his address to the Athenians: 
 *' The one call'd Helix, soon as day retires, 
 
 Observed with ease lights up his radiant fires. 
 
 The other, smaller, and with feebler beams, 
 
 In a less circle drives its laz,y teams ; 
 
 But more adapted for the sailor's guide, 
 
 Whene'er, by night, he tempts the briny tide." 
 
 In the Egyptian planispheres of remote antiquity, these two constellations are repre- 
 sented by the figures of bears, instead of wagons; and the Greeks,who derived most of th M.- 
 astronomical symbols from the Egyptians, though they usually altered them to emblems 
 of their own history or superstition, have, nevertheless, retained the original form of 
 the two bears, It is said by Aratus, that the Phrenician navigators made use of Ursa 
 Minor in directing their voyages : 
 
 " Observing this, Phoenicians plough the main :" 
 
 while the Greeks confined their observations to Ursa Major. 
 
 Some imagine that the ancient Egyptians arranged the stars near the North Pole, 
 within the outlines of a bear, because the polar regions are the haunts of this animal, 
 and also because it makes neither extensive journeys nor rapid marches. 
 
 At what period men began to sail by the stars, or who were the first people that did 
 BO, is not clear; but the honoris usually given to the Phoenicians. That it was prac- 
 ticed by the Greeks, as early as the time of the Trojan war, that is, about 1200 years 
 B. C., we learn from Homer ; for he says of Ulysses, when sailing on his raft, that 
 
 " Placed at the helm he sate, and mark'd the skies, 
 Nor closed in sleep his ever watchful eyes." 
 
 It is rational to suppose that the stars were first used as a guide to travellers by land, 
 for we can scarcely imagine that men would venture themselves upon the sea by night, 
 before they had first learned some safe and sure method of directing their course by 
 land. And we find, according to Diodorus Siculus, that travellers in the sandy plains of 
 Arabia were accustomed to direct their course by Vie Bears. 
 
 That people travelled in these vast deserts at night by observing the stars, is directly 
 proved by this passage of the Koran : " God has given you the stars, to be guided in 
 the dark, both by land and by sea." 
 
 TELESCOPIC OBJECTS. 
 
 1. a URSA MAJOEIS (Diibhe, one of the pointers) A. fine star with a distant compa- 
 nion ; R. A. lOh. 53m. 48s. ; Dec. N. 62 36' 8". A 1 ^, yellow ; B 8, yellow. 
 
 2. (3 URSA MAJORIS (Merafc) A bright star with a distant companion ; R. A. lOh. 52m. 
 OS"; Dec. N. 57 14' 2". A 2, greenish while ; B 11, pale grey other stars in field. 
 
 3. y URSA MAJORIS (Phad)K star with a distant companion ; R. A. lib. 45m. 23s. ; 
 Dec. N. 54 35' 1". A 2, topaz yellow ; B 9, ashy paleuess, with a fine group of stars in 
 the field. 
 
 4. 6 URSA MAJORIS (Megrez) A fine star, suspected of variability, with a distant com- 
 panion; R. A. 12h. 07m. 28s.; Dec. N. 57 55' 3". A 3, pale yellow; B9, ash colored, 
 with other stars in field. . . 
 
 5. (, URSA MAJORIS (Misar.) A splendid double star in the middle of the tail ; R. A. 
 13h. 17m. 2Ss.; Dec. N. 55 45' 8". A 3, brilliant white ; B 5, pale emerald. Alcor and 
 other stars in the field. Map VIII. Fig. 7. 
 
 TKLESCOPIC OBJECTS. Alpha ? Beta? Gamma? Delta? Zeta? Eta? Iota? Nu 
 Wl -it nebula? Which shown on tie map? 
 
COMA BERENICES. 77 
 
 6. n URSA MAJORIS (Benetnasch)\ DOUBLE STAR in the tip of the tail; R. A. 18h.41m. 
 i.4s. ; Dec. N. 50 06' 5". A 2)6, brilliant white ; B 9, dusky. 
 
 7. i URSA MAJORIS (Al KaphraK) A DOUBLE STAR in the right fo -e paw ; R. A. 8h. 48m. 
 14s. ; Dec. N. 48 39' 9". A 3 }, topaz yellow; B 13, purple. Sir J. Uerschel supposed A 
 might be a satellite, shining only by reflection. 
 
 8. v URSA MAJORIS A delicate DOUBLE STAR in the left hind foot, just above or 
 El Acola ; R. A. llh. 09m. 49s. ; Dec. N. 30 58' 0'. A 4, orange tint ; B 12, cornelian blue ; 
 a close but elegant object. 
 
 9. A beautiful PLANETARY NEBULA, just south of /3 ; R. A. lOh. 23m. 45s. ; Dec. N. 54' 
 20' 4*. A small, well denned object, bluish white, and brightens towards the center. 
 
 10. A BRIGHT NEBULA in the right fore leg ; R. A. 9h. 10m. 54s.; Dec. N. 51 40' 5". Of a 
 pale creamy whiteness, with several bright stars in the northern part of the field. 
 Nebula large, elliptical and nucleated. 
 
 11. A bright-class ROUND NEBULA above the Bear's ear ; R. A. 9h. 34m. 32s. ; Dec. N. 78* 
 01' 2". Several stars in field, of 9th to J2th magnitude. 
 
 12. A FINE OVAL NEBULA in the ear ; R. A. 9h. 42m. 10s. ; Dec. N. 69 51' 8*. 
 
 13. A LARGE MILK-WHITE NEBULA on the body, about 1 south of ft or Merak ; R. A. llh. 
 02m. 02s. ; Dec. N. 56 31' 8". 
 
 14. A LARGE PLANETARY NEBULA on the Cank, with several stars in the field, one of 
 which is pretty close ; R. A. llh. 05m. 24s. ; Dec. N. 55 52' 9- About 2 to the S. E. of 
 /3, and just south of a line from (3 to y ; a singular object, circular, uniform, and seem- 
 ingly of the size of Jupiter. W. Uerschel assigned this object to the 980th order of dis- 
 tance. Map VIII., Fig. 42. 
 
 15. A BRIGHT-CLASS NKBULA in a poor field, behind the left hind leg, one-third the dis- 
 tance from 6 towards Denebola; R. A. llh. 58m. 51s.; Dec. N. 48 57' 3". Of a lucid 
 white, various and elongated. Map VIII., Fig. 43. 
 
 16. A LARGE WHITE NEBULA near the haunches ; R. A. 12h. llm. 04s. ; Dec. N. 48 11' 1\ 
 A noble-sized oval, with a bright nucleus, the lateral edges better defined than the ends) 
 Found by running a diagonal line across the square, from a through y, and about 7J$* 
 beyond, into the S. E. 
 
 COMA BERENICES (BERENICE'S HAIR). MAP IV. 
 
 152. This is a beautiful cluster of small stars, situated about, 
 5 E. of the equinoctial colure, and midway between Cor Caroli 
 on the northeast, and Denebola on the southwest. If a straight 
 line be drawn from Benetnasch through Cor Caroli, and pro- 
 duced to Denebola, it will pass through it. 
 
 153. The principal stars are of between the 4th and 5th mag- 
 nitudes. According to Flamsted, there are thirteen of the 4th 
 magnitude, and according to others there are seven ; but the 
 student will find agreeably to his map, that there is apparently 
 but one star in this group, entitled to that rank, and this is 
 situated about t S. E. of the main cluster. 
 
 Although it is not easy to mistake this 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 tho 
 full presence of the moon. The confused lustre of this assemblage of small stars some- 
 what resembles that of the Milky Way. 
 
 152 Describe Coma Berenices? How find it? 158. Its principal tars, their numbct 
 &c.? What remark in fine print? 
 
78 ASTRONOMY. 
 
 154. The whole number of stars in this constellation is 43 ; 
 its mean right ascension is 185. It consequently is on tho 
 meridian the 13th of May. 
 
 " Is ow behold 
 
 The glittering maze or Berenice's Hair; 
 Forty the stars ; but such as seem to kisa 
 Ihejfen0fo# ti-essts with a lambent fire, 
 Four to the telescope alone are seen." 
 
 HISTORY. 
 
 Berenice was of royal descent, and a lady of great beauty, who married Ptolemy Soter, 
 or Evergetes, one of the kings of Egypt, her own brother, whom she loved with much 
 tenderness. When he was going on a dan^vi'ous expedition against the Assyrians, shs 
 vowed to dedicate her hair to the goddess of beauty, if he returned in safety. Some 
 time after the victorious return of her husband, Evergetes, the locks, which, agreeably 
 to her oath, she had deposited in the temple of Venus, disappeared. The king expressed 
 great regret at the loss of what he so much prized ; whereupon Conon, his astronomer, 
 publicly reported that Jupiter had taken away the queen's locks from the temple and 
 placed them among the stars. 
 
 " There Berenice's locks first rose so bright, 
 
 The heavens bespangling with dishevelled light." 
 
 Conon being sent for by the king, pointed out this constellation, saying, " There behold 
 the locks of the queen." This group being among the unformed stars until that time, 
 end not known as .1 constellation, the king was satisfied with the declaration of the 
 astronomer, and the queen became reconciled to the partiality of the gods. 
 
 Callimachus, a historian and poet, who flourished long before the Christian era, has 
 these lines as translated by Tytler : 
 
 "Immortal Conon, blest with skill divine, 
 Amid the sacred skies beheld me shine: 
 E'en me, the beuuieoiix hitir, that lately shed 
 Refulgent beams from Berenice''* head ; 
 The luck she fondly vowed with lifted rms, 
 Imploring all the powers to save from inarms 
 Her dearer lord, when from his bride im flew, 
 To wreak stern vengeance on the Assyrian crew." 
 
 TELESCOPIC OBJECTS. 
 
 1. A TRIPLE STAR, between the tresses and Virgo's northern wing; R. A. 12h. 45m. 25s. , 
 Dec. N. 22 07' 0". A 5, pale yellow; B, indistinct; C 10, cobalt blue. About 7 south, 
 east of a Berenices, and 20 west of Arcturus. 
 
 2. A GLOBULAR CLUSTER, between the tresses and the Virgin's left hand, with a coarse 
 pair and one single star in the field; R. A. 11 h. Oom. 03s. ; Dec. N. 19' 01 3". A brilliant 
 mass of minute stars from the llth to the 15th May; compressed at center. A line 
 through (5 and F Virginia, northward, meeting another from Arcturus over ty Bootes, falls 
 upon this magnificent object. 
 
 8. A CONSPICUOUS NKBn.A between the tresses and the virgin's left arm; R. A. 12h. 
 48iu. 52s. ; Dec. N. 22 84 2". A magnificent object, both in size and brightness, witfc 
 several siuail stars in the field. Elongated, compressed in the centre, and was likened 
 *y Sir Charles Blagdon to a " black eye." Map V1I1., Fig. 44. 
 
 CORVUS (THE CEOW). MAP IY. 
 
 155. This small constellation is situated on the eastern part 
 of Hydra, 15 E of the Cup, and is on the same meridian with 
 
 154. What number of stars? 
 
 HISTOKY. -Who was Berenice? Story of the loss of her hair, 4c.? 
 
 TKI.E,->OOPIC OBJKCTS. What triple stars? Cluster? Nebula? Point out on the Mao. 
 
 155. Where ia Corvus situated? Number of vidible stars? 
 
CORVUS. 79 
 
 Coma Berenices, but as far S. of the equinoctial as Coma Bere- 
 nices 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. 
 
 156. 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, the two upper ones being about 
 3| apart, and the two lower ones 6 apart. 
 
 157. The brightest of the two upper stars, on the left, is 
 called Algorab, and is situated in the E. wing of the Crow ; it 
 has nearly the same declination 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 Yirginis, a brilliant star 
 of the 1st magnitude, to be described in the next chapter. 
 
 158. 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 Beta, and may be known 
 by a star of the same magnitude situated 2 below it, in the eye, 
 and called AL Chiba. Epsilon is 21| S. of the vernal equinox, 
 and if a meridian should be drawn from the pole through 
 Megrez, and produced to Epsilon Corvi, it would mark the equi- 
 noctial colure. 
 
 )59. Gamma, in the W. wing, is a star of the 3d magnitude, 
 3^- W. of Algorab, and is the upper right-hand on^ in the 
 square. It is but 1 E. of the equinoctial colure. 
 
 10 E. of Beta is a star of the 3d magnitude, in the tail of 
 Hydra, marked Gamma ; these two, with Algorab, form nearly 
 a right-angled triangle, the right angle being at Beta. 
 
 HISTORY. 
 
 The Crow, it is said, was once of the purest white, but was chan-ed for tale-bearing to 
 its present color. A fit punishment for such a fault. 
 
 *'The raven once in snowy plumes was drest, 
 White as the whitest dove's unsullied brcsst, 
 Fair as the guardian of the capitol, 
 Soft ai the Swan ; a large and lovely fowl ; 
 His tongue, his prating tongue, had changed htm quii/c, 
 To sooty blackness from the purest white." 
 
 According to Greek fable the Crow was made a constellation by Apollo. This goj 
 be.'ng jealous of Coronis (whom he tenderly loved), the daughter of Phlegyas and 
 
 156. How is it found ? 157. What said of Algorab ? 153. Of Beta ? Epsilon ? 
 Al Chiba? What said of the Pole, Megrez, and Epsilou? 159. Of Gamma? What 
 triangle ? 
 
 HISTORY. Story of the original color of Corvus ? Greek fable of the origin of tb- 
 ccastellation ? What other account ? 
 
80 ASTRONOMY. 
 
 mother of JEsculapius, sent a crow to watch her behavior; the bird perceived her cri- 
 minal partiality for Ischys the Thessalian, and immediately acquainted Apollo with hei 
 conduct, which so fired his indignation that he lodged an arrow in her breast, and killed 
 l.er instantly. 
 
 " T le god was wroth ; the color left his look, 
 
 The wreath his head, the harp his hand forsook : 
 
 The silver bow and feathered shafts he took, 
 
 And lodged an arrow in the tender breast, 
 
 That had so often to his own been prest." 
 To reward the crow, he placed her among the constellations. 
 
 Others say that this constellation takes its name from the daughter of Corona?us, 
 king of Phocis, who was transformed into a crow by Minerva, to rescue the maid from 
 the pursuit of Neptune. The following, from an eminent Latin poet of the Augustan 
 age, is her own account of the metamorphosis as translated into English verse by Mr. 
 Addison : 
 
 " For as my arms I lifted to the skies, 
 I saw black feathers from my fingers rise ; 
 I strove to fling my garment on the ground ; 
 My garment turned to plumes, and girt me round; 
 My hands to beat my naked bosom try ; 
 Nor naked bosom now, nor hands had ! 
 Lightly I tripp'd, nor weary as before 
 Sunk in the sand, but skimm'd along the shore ; 
 Till, rising on my wings, I was preferr'd 
 To be the chaste Minerva's virgin bird." 
 
 TELESCOPIC OBJECTS. 
 
 1. jtf CORVI A fine bright star nearly midway between two distant companions. A 2?$, 
 ruddy yellow ; B 7, greenish yellow ; C 8, dull grey, ft is actually the lucida, or brightest 
 star of the constellation. 
 
 2. J CORVI A DOUBLE STAR in the right wing ; R. A. 12h. 21m. 85s. ; Dec. S. 15 37' 04" 
 A 3, pale yellow ; B 8 Jg, purple. 
 
 VIRGO (THE VIRGIN). MAP IV. 
 
 160. 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 
 occupies 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 con#tella~ 
 tton before the 15th of September. When the sun is in this sign, the earth is in Pisces ; 
 and vice versa. 
 
 161. Alpha, or Spica Virgims, 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 in 
 the Crow, about 35 S. E. of Denebola, and nearly as far S. S. 
 
 TELESCOPIC OBJECTS. Beta ? Delta ? 
 
 160. Order and position of Virgo? Extent? Number of stars? Magnitudes? Mear 
 declination of Virgo? JJeicark in fine print? 161. What said of Alpha, or Spica Vir 
 
VIRGO. 81 
 
 W. of Arcturus three very brilliant stars of similar magnitude 
 rhat form a large equilateral triangle, pointing to the S. Arc- 
 turus and Deuebola 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. 
 
 162. The length of this figure, from Cor Caroli, on the north, 
 Co 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 soli- 
 tary splendor, there being no visible star near it except one of 
 the 4th 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 longitude at sea. Its situation is highly favorab'e for this purpose, 
 is it lies within the moon's path, and little more than 2 below the ear'h's orbit. 
 
 Its right ascension being 199, it will come to our meridian at 9 o'clock about the 23th 
 5f May, in that point of the heavens where the sun is at noon about the 20th of October. 
 
 ] 63. Beta, called also Zavijava, is a star of the 3d magni- 
 tude, in the shoulder of the wing, 7^- W. of Eta, with which 
 and Gamma it forms a line near the Earth's orbit, and parallel 
 to it. Beta, Eta, Gamma and Spica, form the lower and longer 
 side of a large spherical triangle whose vertex is in Beta. 
 
 164. Vindemiatrix, is a star of the 3d magnitude, in the right 
 arm, or northern wing of Yirgo, and. is situated nearly in a 
 straight line with, and midway between Coma Berenices and 
 Spica Yirginis. It is 19|- S. 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 Deuebola, and comes to the meridian about 23 
 minutes before Spica Virginis. 
 
 165. Zeta, is a star of the 3d magnitude, 11^- j$T. 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 equi- 
 noctial. It is 13 due west of Zeta, with which and Spica it 
 forms a handsome triangle. Eta, is a star of the 3d magnitude 
 "n the southern wing, 5 W. of Gamma, and but 2 E. of the 
 autumnal equinox. 
 
 The other stars in this figure may be easily traced by means of the map. About 13 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 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 8d magnitude lie scattered about 
 in t-his constellation, and may be traced out by the map. 
 
 ginis? Diamond? 162. Length of Virgo? Breadth? How may Spica be known? 
 Vote in fine print? 163. Describe Beta? What triangle? 164. V.ndematrLx ? 
 
 165. Zeta, Gamma and Eta ? What other stars and how found? 
 
82 ASTRONOMY. 
 
 
 
 " 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, 
 toutjinit the star which crowns the golden sheaf." 
 
 HISTORY. 
 
 According to the ancient poets, this constellation represents the Virgin Astrsea, .he 
 goddess of justice, who lived upon the earth during the golden age ; but being off.-.id^d 
 at the wickedness and impiety of mankind during the brazen and iron ages of the world, 
 she returned to heaven, and was placed among the constellations of the zodiac, with a 
 pair of scales (Libra) in one hand and a sword in the other. 
 
 Hesiod, who flourished nearly a thousand years before the birth of our Saviour, and 
 later writers, mention four ages of the world ; the golden, the silver, the brazen, and the 
 iron age. In the beginning of things, say they, ail men were happy, and all men were 
 good; the earth brought forth her fruits without the labor of man; and cares, and 
 wants, wars and diseases, were unknown. But this happy state of tilings did not last 
 long. To the golden age, the silver age succeeded ; to the silver the brazen ; and to the 
 brazen, the iron. Perpetual spring no longer reigned ; men continually quarreled with 
 each other ; crime succeeded to crime ; and blasphemy and murder stained the hisiory 
 of every day. In the golden age, the gods did not disdain to mix familiarly with the 
 sons of men. The innocence, the integrity and brotherly love which they found among 
 us, were a pleasing spectacle even to superior natures; but as mankind degenerated, 
 one god after another deserted their late beloved haunts; Astraja lingered the last; but 
 finding the earth steeped in human gore, she herself new away to the celestial regions. 
 
 " Victa jacet pietas; et virgo caede madentes 
 
 Ultima ccelestuin terras Astrasa reliquit." 
 Met. Lib. i. v. 149. 
 "Faith flees, and piety in exile mourns; 
 
 And justice here oppresb'd, to heaven returns." 
 
 Some, however, maintain, that Erigone was changed into the constellation Virgo. The 
 death of her father Icarus, an Athenian, who perished by the hands of some peasants, 
 whom he had intoxicated with wine, caused a fit of despair, in which Erigone hung her- 
 self; and she was afterward, as it is said, placed among the signs of the zodiac. She 
 was directed by her faithful dog Maera to the place where her father was slain. The 
 first bough on which she hung herself breaking, she sought a stronger, in order to effect 
 her purpose. 
 
 " Thus once in Marathon's impervious wood, 
 Erigone beside her father stood, 
 
 When hastening to discharge her pious vows, . 
 
 She loos'd the knot, and cull'd the strongest boughs." 
 LEWIS' Statius, B. xi. 
 
 The famous zodiac of Dendera, as we have already noticed, commences with the sigi? 
 Leo ; but another zodiac, discovered among the ruins at Esne, in Egypt, commences with 
 Virgo; and from this circumstance, 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 Esne was erected during the reign of the Emperor Claudius, and conse- 
 quently did not precede the one at Dendera more than fourteen years. 
 
 Of this, however, we may be certain : the autumnal equinox now corresponds 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 precision 5054" 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 per- 
 haps to the patriarch himself, who constructed it for the benefit of those who should live 
 after the deluge, and who preserved it as a monument to perpetuate the actual state of 
 the heavens immediately subsequent to the creation. 
 . 1 
 
 HISTORY. Account of the poets? Hesiod's ace rant? What other supposition? Wl.a 
 Bodiitcs mentioned, and what calculations, &c. ? 
 
CANES VENATICI. 83 
 
 TELESCOPIC OBJECTS. 
 
 I. a VIRGINTS (Spica) A splendid star with a minute companion ; R. A. 13h. 16m. 47s. 
 l>c. S- 10 19 5". A 1, brilliant flushed white; B 10, bluish tinge. 
 
 2 j3 VIRGIXIS (Zat'ijuri) A bright star with a small companion ; R. A. llh. 42m. 22s. ; 
 Dec. N. 2 4u' 0". A 8>$, pale yellow ; B 11, light blue. 
 
 3. y VIRGINIS A fine BINARY STAR in the Virgin's right side ; R. A. 12h. 33m. 83s. ; Dec. 
 S. 34' 3". A 4, silvery white ; B 4, pale yellow. A Binary System with a period of 
 about 157 years. Map. VIII. Fig. 8. 
 
 4. ri VIRGIXIS A star with a distant companion, on the left side, about 17 north-north- 
 west of Spica, and nearly midway between y and e Virginis ; R. A. 12h. 47m. 33s. ; Dec. 
 N. 4 16' 1'. A 3^, golden yellow ; B 10^, reddish ; several small stars in the field. 
 
 5. e VIRGIMS ( Vendemiatrivc) A star with a minute distant companion, on the upper 
 extremity of the Virgin's left wing ; R. A. T2h. 64m. 13s. ; Dec. 11 49 03". A 3%, bright 
 yellow ; B 15, intense blue. This last color on so small an object is very striking. 
 
 6. A TRIPLE STAR in the lower part of the southern wing, 7 northwest of Spica ; R. A. 
 V3h. Olni. 40s. ; Dec. S. 4" 41' 0'. A 4^, pale white ; B 9, violet ; C 10, dusky. 
 
 7. A LARGE, BUT RATHER PALE NEBULA, between Virgo's left wing and Leo's tail ; R. A. 
 12h. 06n-.. Ols.; Dec. N. 15' 47 02". About 6^ from tf Leonis, towards Arcturus, on the 
 outskirts of a vast region of Nebula in the Virgin's wing. It is elongated in the directicn 
 of two telescopic stars. 
 
 8. A LONG PALE-WHITE NEBULA, among telescopic stars, on the upper part of the Vir- 
 gin's left wing; R. A. 12h. ()7in. 37s. ; Dec. N. 14" 02' 08". Situated one-third of the way 
 from /3 Leonis to e Virginis, on the border of the vast nebulous region in Virgo. A 
 curious object in the shape of a weaver's shuttle. 
 
 9. A LUCID WHITE ELLIPTICAL NEBULA, between the Virgin's right elbow and the Crow ; 
 R. A. J2h. 31m. 40s. ; Dec. S. 10 43' 07". Map VIII., Fig. 45. 
 
 10. A DOUBLE NEBULA in the center of Virgo's left wing; R. A. 12h. 35m. 33s. ; Dec. N. 
 12 26' 01". It is 5" west of Vendemiatrix, toward Regulus, in a wonderful nebulous 
 region. Map VIII., Fig. 46, shows it on the right, with two other nebulae, and several 
 stars in the figure. 
 
 II. A PALE ELLIPTICAL NEBULA, in the middle of the left wing; R. A. 12h. 44m. 50s., 
 Dec. N. 12" 05' 09". It looks like a paper kite, under an ar.ch formed by three telescopic 
 stars. Map. VIII., Fig. 47. 
 
 12. A WONDFRFUL NEBULOUS REGiox, about 2^" from north to south, and 3" from east to 
 west, is found on the left wing. It includes several of the objects described. For a 
 arawing of this remarkable field, see Map VIII., Fig. 48. 
 
 CANES YENATIOI (THE GREYHOUNDS). MAP IV. 
 
 166. 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 heliolds in his hand the 
 leash by which they are fastened together. The northern one is called Juttnim, and 
 the southern one, Cluira. 
 
 TELESCOPIC OBJECTS. Alpha? Beta? Gamma? Delta? Epsilon? What triple star f 
 Nebula? Point out on the map. 
 
 166. Situation of Canes Venatici ? By whom formed ? How represented ? Nameo of 
 *ie hounds ? 
 
 4* 
 
84 ASTRONOMY. 
 
 167. The stars in this group are considerably scattered, and 
 are principally of the 5th and 6th magnitudes ; of the twenty- 
 five stars which it contains, there is but one sufficiently large to 
 engage our attention. Cor Caroli or CharkJ Heart, so named 
 by Sir Charles Scarborough, in memory of King Charles the 
 First, is a star of the 3d magnitude, in the neck of Chara, the 
 southern Hound. 
 
 When on the meridian, Cor Caroli is 17%" directly S. 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 N. polar star. This star 
 may also be readily distinguished by its being in a straight line with, and midway between 
 Benetnasch, 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, Denebola bears 28 S. W. and Arcturus 
 26 S. E. of it, forming with these two stars a very large triangle, 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. 
 
 1 A DOUBLE STAR near Chara's mouth ; R. A. 12h. 08m. 06s. ; Dec. N. 41 33' 01". A 6, 
 yellow; B 9, blue. It is about 9 south of Cor Caroli, and one-third of the distance 
 between that star and d Leonis. Map VIII., Fig. 10. 
 
 2. A MAGNIFICENT CLUSTER, between the southern Hound and the knee of Bootes; R. A. 
 13h. 34m. 45s. A splsndid group, supposed to contain not less than 1,000 stars. Map 
 VIII., Fig. 49. 
 
 3. A PAIR OF LUCID WHITE NEBULAE, near the ear of the northern Hound ; R. A. 13h. 23m. 
 06s. ; Dec. N. 48" 01' 07". 
 
 4. A LARGE BRIGHT NEBULA, 2% north by west of Cor Caroli ; R. A. 12h. 43m. 22s. ; Dec. 
 N. 41 59' 07". A fin.i pale-white object, compressed toward the center, and with several 
 small stars in the field. 
 
 CHAPTER VIII. 
 
 CONSTELLATIONS ON THE MERIDIAN IN JUNE 
 
 BOOTES (THE BEAK DRIVER). MAP IV. 
 
 1 68. THE BEAR-DRIVER is represented by the figure of a hunts- 
 man in a running posture, grasping a club in his right hand, and 
 holding up in his left the leash of his two greyhounds, 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." 
 
 167. Describe the stars in this group? Cor Caroli? 
 
 TELESCOPIC OBJECTS. What double star ? Show on the map ? Clusters? Point out ou 
 Che map? Nebulae? 
 
 l<>8. Describe Bootes ? Why called the P.ear-Driver* 
 
BOOTES. b 
 
 169. This constellation is situated between Corona Borealis 
 on the east, aid Cor Caroli, or the Greyhounds, on the west. 
 It contains fifty-four stars, including one of the 1st magnitude, 
 seven of the 3d, and ten of the 4th. Its mean declination is 20 
 N., and its mean right ascension is 212 ; its center is there- 
 fore on the meridian the 9th of June. It may be easily distin- 
 guished by the position and splendor of its principle star, Arc- 
 turns, which shines with a reddish luster, Tery much resembling 
 that of the planet Mars. 
 
 170. Arcturus 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 elongated triangle, whose vertex is at Arc 
 turus. It is 35^- E. of Denebola, and nearly as far N. of Spica 
 Virginis, and forms with these two, as has already been observed, 
 a large equilateral triangle. It also makes, with Cor Caroli and 
 Denebola, a large triangle whose vertex is in Cor Caroli. 
 
 A great variety of geometrical figures may be formed of the stars in this bright region 
 of the skies. For example : Cor Caroli on the N., and Spica Virginis on the S., constitute 
 the extreme points of a very large figure in the shape of a diamond ; while Denebola on 
 the W. and Arcturus on the E., limit the mean diameter <^t the other points. 
 
 171. Arcturus is supposed by some to be nearer the Earth 
 than any other star in the northern hemisphere. 
 
 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. 
 
 172. Mirac, in the girdle, is a star of the 3d magnitude, 10 
 N. N. E. of Arcturus, and about 11^ W. of Alphacca, a star in 
 the Northern Crown. Seginus, 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. The same 
 star forms a right-angled triangle with Cor Caroli and Alioth, 
 in Ursa Major, the right angle being at Cor Caroli. 
 
 173. Alkaturops, situated in the top of the club, is a star of 
 the 4th magnitude, about 10^- in an easterly direction from 
 Seginus, 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. Delta is about 9 P dis- 
 tant from Mirac, and 7 from Alphacca, and forms, with these 
 two, a regular triangle. 
 
 1G9. How situated? How many stars, and their magnitude? Declination? How dis- 
 tinguished? 170. Describe Arcturus, and its position ? What triangles? what dia- 
 mond? 171. Supposed nearness of Arcturus? 172. Describe Mirac and Seginus r 
 'Vhat triangles? 173. Situation and magnitude of Alkaturops? Of Delta? 
 
Sty ASTRONOMY. 
 
 174. Nekkar is a star of the 3d magnitude, situated in the 
 head, and is about 6 N. E. of Seginus, and 5 ' W. of Alkatu- 
 rops ; it forms, with Delta arid Seginus, nearly a right angled 
 triangle, the right angle being at Nekar. 
 
 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 Dip- 
 per. About 6 E. 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. 
 
 175. The three stars in the left hand of Bootes, the first in 
 the handle of the Dipper, Cor Caroli, Coma Berenices, and 
 Denebola, are all situated nearly in the same right line, running 
 from northeast to southwest. 
 
 " Bootes follows with redundant light; 
 Fifty-four stars he boasts ; one guards the Bear, 
 Thence call'd Arcturus, of resplendent front, 
 The pride of the first order: eight are veil'd, 
 Invisible to the unaided eye." 
 
 MANILIUS thus speaks of this constellation : 
 
 " And next Bootes comes, whose order'd beams 
 Present a figure driving of his teams. 
 Below his girdle, near his knees, he bears 
 The bright Arcturus, fairest of the stars." 
 
 176. Arcturus is mentioned by name ia that beautiful passage 
 in Job, already referred to, where the Almighty answers ''out 
 of the whirlwind," and says : 
 
 " Canst thou the sky's benevolence restrain, 
 And cause the Pleiades to shine in vain? 
 Or, when Orion sparkles from his sphere, 
 Thaw the cold seasons and unbind the year? 
 Bid Mazzarotn his wonted station know, 
 And teach the bright Arcturus where to glow?" 
 
 Young's Paraphrase. 
 
 HISTORY. 
 
 The ancient Greeks called this constellation Lycaon a name derived from Au/co?, 
 which signifies a wolf. The Hebrews called it Caleb Anubuch, the " Barking Dog ;" 
 while the Latins, among other names, called it Cani*. If we go back to the time when 
 Taurus opened the year, and when Virgo was the fifth of the zodiacal signs, we shall 
 find that brilliant star Arcturus, so remarkable for its red and fiery appearance, corres- 
 ponding with a period of the year as remarkable for its heat. Pythagoras, who intro- 
 duced the true system of the universe into Greece, received it from (Enuphis, a priest of 
 On, in Egypt. And this college of the priesthood was the noblest of the east, in cultivat- 
 ing the studies of philosophy and astronomy. Among the high honors which Pharaoh 
 conferred on Joseph, he very wisely gave him in marriage " a daughter of the priest of 
 On." The supposed era of the book of Job, in which Arcturus is repeatedly mentioned, 
 is 1518 B. C. 
 
 Bootes is supposed by some to be Icarus, the father of Erigone, who was killed by 
 shepherds for intoxicating them. Others maintain that it is Erichthouius, the inventor 
 of chariots. According to Grecian fable, as well as later authorities, Bootes was the son 
 of Jupiter and Calisto, and named Areas. Ovid relates, that Juno, being incensed at 
 Jupiter for his partiality to Calisto, changed her into a bear, and that her son Areas, who 
 became a famous hunter, one day roused a bear in the chase, and not knowing that it 
 
 174. Of Nekkar? Any other stars? 175. What said of three stars in the hand of 
 Bootes? 176. What star in Bootes mentioned in the Scriptures? Poetic quotation ? 
 HISTORY. Greek name of this constellation? Hebrew? Grecian fable? Ovid' 
 
BOOTES. 8? 
 
 WAS his mother, was about to kill her, when Jupiter snatched them both up to heaven 
 and placed then among the constellations. Met. b. ii. v. 49d-50S. 
 
 u But now her son had fifteen summers told, 
 Fierce at the chase, and in the forest bold ; 
 When as he beat the woods in quest of prey, 
 rle chanced to rouse his mother where she lay. 
 She knew her son, and kept him in her sight, 
 And fondly gazed : the boy was in a fright, 
 And aim'd a pointed arrow at her breast ; 
 And would have slain his mother in the beast: 
 But Jove forbade, and snatch'd them through the air 
 In whirlwinds up to heaven, and fix'd 'em there; 
 Where the new constellations nightly rise, 
 And add a luster to the northern skies." 
 
 GatW* Translation. 
 LUCAN, in his Pharsalia, says 
 
 " That Brutus, on the busy times intent, 
 To virtuous Cato's humble dwelling went, 
 'Twas when the solemn dead of night came on, 
 When bright Culixto, with her nhining xon, 
 Now half that circle round the pole had run." 
 
 This constellation is called Bootfs, says Cicero (Nat. D?o. Lib. ii. 41'), from a 
 word signifying a wagoner, or ploughman ; and sometimes Arctvphylax from 
 words signifying bear-keeper or bear-driver. 
 
 " Arctophylax, vulgo qui dicitur esse Bootes, 
 Quod quasi temone adjunctum prae se quatit Arctum." 
 
 The stars in this region of the skies seem to have attracted the admiration of almoct 
 n.11 the eminent writers of antiquity. Claudian observes, that 
 
 " Bootes with his wain the north unfolds; 
 The southern gate Orion holds." 
 
 And Aratus, who flourished nearly SOO years before Claudian, says, 
 "Behind, and seeming to urge on the Bear, 
 A"<Jtophylax, on enrth Bootes named, 
 SheJs o'er the Arctic car his silver light." 
 
 This is the poet whom St. Paul refers to when he tells the Athenians, Acts xvii. 23, that 
 "some of their own poets have said, 'Tow yap vat yevo, ecruev :' For we are also 
 his offspring." These words are the beginning of the 5th line of the "Phenomena" of 
 Aratus, a celebrated Greek poem written it. the reign of Ptolemy Philadelphus, two 
 thousand one hundred years ago, and afterward translated into Latin verse by Cicero. 
 Aratus was a poet of St. Paul's own country. The apostle borrows again from the same 
 poet, both in his Epistle to the Galatians, and to Titus. The tfuf>jevt of the poem was 
 
 5 rand and interesting: hence we find it referred to in the writings of St. Clement, St. 
 erome, St. Chrysostom, (Ecumenius, and others. As this poem describes the nature and 
 motions of the stars, and the origin of the constellations, and is, moreover, one of the 
 oldest compositions extant upon this interesting subject, the author has taken some 
 pains to procure a Polyglot copy from Germany r , together with the Axtronomicon of 
 Manilius, and some other works of similar antiquity, that nothing should be wanting on 
 his part which could impart an interest to the study of the constellations, or illustrate 
 the frequent allusions to them which we meet with in the Scriptures. 
 
 Dr. Doddridge says of the above quotation, that " these words are well known to be 
 found in Aratus, a poet of Paul's own country, who lived almost 8'>0 years before the 
 apostle's time; and that the same words, with the alteration of only one letter, mre to 
 be found in the Hymn of Cl, anthe*, to Jupiter, the Supreme God; which is, beyond 
 comparison, the purest and finest piece of n-titu-'dl religion, of its length, which I know 
 in the whole wor'd of Pagan antiquity; and which, so far as 1 can recollect, contains 
 nothing unworthy of a Christian, or, I had almost said, of an inspired pen. The apostle 
 might perhaps refer to Clfanth'H, as well as to his countryman Aratus." 
 
 Many of the elements and fables of heathen mythology are so blended with the 
 
 account? Lucan and Cicero? Claudian? Aratus? Who was Aratus? What remark 
 able quotation ? Remark of Doddridge ? What other passage cited by St. Paul ? Fronc 
 whom ? 
 
88 ASTRONOMY. 
 
 Inspired writings, that they must needs be studied, more or less, in order to have a morr 
 proper understanding of numerous passages both in the Old and New Testament. 
 
 The great apostle of the Gentiles, in uttering his inspired sentiments, and in penning 
 his epistles, often refers to and sometimes quotes verbatim from the distinguished writers 
 who preceded him. 
 
 Thus, in 1 Cor. xv. 33, we have " M?; TrliavasOe' 'Qdetpovctv rjdrj XpTjaO' o/ui'hiai 
 cot/cat.' Be not deceived; evil communications corrupt good manners;" which is a 
 flteral quotation by the apostle from the Thais of Menander, an inventor of Greek 
 comedy, and a celebrated Athenian poet, who flourished nearly 400 years before the 
 apostle wrote his epistle to the Corinthians. Thus Paul adopts the sentiment of the 
 jomedian, and it becomes hallowed by " the divinity that stirred within him." Tertul- 
 ;ian remarks, that " in quoting this, the apostle hath sanctified the poet's sentiment." 
 
 TELESCOPIC OBJECTS. 
 
 1. a Boons (Arcturus) A. DOUBLE STAR ; R. A. 14h. 08m. 22s. ; Dec. N. 20" 00' 9". A 1, 
 A eddish yellow; B 11, lilac. 
 
 2. /3 Boons (Nfkka-r) A star with a distant companion in the head of the figure ; R. A- 
 I4h. 55m. 55s. ; Dec. N. 41 01' 5". A 3, golden yellow : B 11, pale grey. 
 
 3. 6 Boons A star with a distant companion in the left shoulder ; R. A . 15h. 09m. 03s.; 
 Dec. N. S3" 54' 9". A 3J6, pale yellow; B 8%, light blue. 
 
 4. e BOOTIS (Mirac) A DOUBLE STAR in the left hip ; R. A. 14h. 38m. OOs. ; Dec. N. 27* 
 45' 1". A 3, pale orange ; B 7, sea green. A lovely objects-colors distinct, and strongly 
 contrasted. 
 
 5. , BOOTIS A close DOUBLE STAR on the left leg ; R. A. 14h. 33m. 31s. ; Dec. N. 14 25' 
 1". A 3J, bright white ; B 4%, bluish white. 
 
 6. 77 BOOTIS (Mufride) A star with a distant companion on the right leg ; R. A. 13h. 
 47m. 04s. ; Dec. N. 19 12' 0". About 5% west by south of Arcturus. A 3, pale yellow ; 
 B 10 Jj, lilac. 
 
 7. i BOOTIS A DELICATE TRIPLE STAR in the right hand (Map VI.) ; R. A. 14h. 10m. 80s.; 
 Dec. N. 52 06' 4*. A and B 4%, pale yellow ; C 8, creamy white. 
 
 8. BOOTIS A BINARY STAR on the left knee ; R. A. 14h. 44m. OOs. ; Dec. N. 19 46' 1* 
 A 3%, orange ; B 6%, purple. Supposed period 400 years. 
 
 9. A RICH GROUP of stars in the vicinity of Arcturus, and surrounding that star. May 
 be seen with small telescopes. Map VIII., Fig. 50. 
 
 10. A PALE WHITE NEBULA in a nebulous field, 5 north northeast of Alkaid ; R. A. 
 i3h. 57m. 81s. ; Dec. N. 55 08' 8". About 5 southeast of Mizar. A difficult object 
 except with a good instrument. 
 
 11. A WHITE ROUND NEBULA near the right shoulder ; R. A. 14h. llm. 44s. ; Dec. N. 87* 
 14' 4". Pale, except at the center telescopic stars in the field. 
 
 JSTOCTA (THE OWL). MAP IV. 
 
 iTt. This small asterismis situated between the feet of Yirgo, 
 on the north, and the tail of Hydra, on the south. It has but few 
 stars, and those only of the 5th and 6th magnitudes. It is often 
 omitted altogether from the constellations. 
 
 CENTAURUS (THE OENTAUE). MAP IY. AND VII. 
 
 178. This fabulous monster is represented by the figure of a 
 man, terminating in the body of a horse, holding a wolf at arm't 
 
 TKLESCOPIC OBJECTS. Alpha? Beta' Delta? Epsilon? Zeta? Eta? Iota? Xif 
 What, rich group? Point out on the m;ip. What nebulae? 
 177. Describe Nocta, its situation, stars, &c. 
 
CENTAURUS. 89 
 
 length in one hand, while he transfixes its body with a spear in 
 the other. 
 
 Although this constellation occupies a large space in the 
 southern hemisphere, yet it is so low down that the main part 
 ol' it cannot be seen in our latitude. It is situated south of 
 Spica Yirginis, with a mean declination of 50. It contains 
 thirty-five stars, including two of the 1st magnitude, one of the 
 2d, and six of the 3d ; the brightest of which are not visible in 
 the United States. 
 
 179. Theta is a star of between the 2d and 3d magnitude, in 
 the east shoulder, and may be seen from this latitude, during the 
 month of June, being about 27 S. by E. from Spica Yirginis, 
 and 12 or 13 above the southern horizon. It is easily recog- 
 nized in a clear evening, from the circumstance that there is no 
 other star of similar brightness in the same region, for which it- 
 can be mistaken. It is so nearly on the same meridian with 
 Arcturus that it culminates but ten minutes before it. 
 
 Iota is a star of between the 4th and 5th magnitude, in the west shoulder, 9j* W. of 
 Theta. It is about 26 almost directly south of Spica Virginis, and is on the meridian 
 nearly at the same time. 
 
 Mu and Nu are stars of the 4th magnitude, in the breast, very near together, and form 
 a regular triangle with the two stars in the shoulders. 
 
 A few degrees north of the two stars in the shoulders, are four small stars in the head. 
 The relative position of the stars in the head and shoulders is very similar to that of the 
 stars in the head and shoulders of Orion. 
 
 HISTORY. 
 
 Centaurs, in mythology, were a kind of fabulous monsters, half men and half horses. 
 This fable is, hrwever, differently interpreted; some suppose the Centaurs to have been 
 a body of shepherds and herdsmen, rich in cattle, who inhabited the mountains of Arca- 
 dia, and to whom is attributed the invention of pastoral poetry. But Plutarch and Pliny 
 are of opinion that such monsters have really existed. Others say, that under the reign 
 of Ixion, king of Thessaly, a herd of bulls ran mad, and ravaged the whole country, 
 rendering the mountains inaccessible ; and that some young men, who had found the art 
 of taming and mounting horses, undertook to expel these noxious animals, which they 
 pursued on horseback, and thence obtained the appellation of Centaurs. 
 
 This success rendering them insolent, they insulted the Lapithse, a people of Thessaly ; 
 and because, when attacked, they fled with great rapidity, it was supposed that they 
 were half horses and half men ; men on horses being at that period a very uncommon 
 light, and the two appearing, especially at a distance, to constitute but one animal. So 
 the Spanish cavalry at first seemed to the astonished Mexicans, who imagined the horse 
 nnd his rider, like the Centaurs of the ancients, to be some monstrous animal of a ter- 
 rible~form. 
 
 The Centaurs, in reality, were a tribe of Lapithae, who resided near Mount Pelion, and 
 first invented the art of breaking horses, as intimated by Virgil. 
 
 " The Lapithas to chariots add the state 
 Of bits and bridles ; taught the steed to bound 
 To turn the ring, and trace the mazy ground; 
 To stop, to fly, the rules of war to know; 
 To obey the rider, and to dare the foe." 
 
 Centaurus is so low down in the south that it would be of no service to describe its tele 
 scopic objects. 
 
 ITS. How is Centaurys represented ? Its situation? Number of stars, & 3.? 179. Theta 
 Iota, Mu, Nu, Ac.? 
 
 HISTORY. What was Centaurus? Different opinions? 
 
93 ASTRONOMY. 
 
 LUPUS (THE WOLF). MAPS V. AND VII. 
 
 180. This constellation is situated next east of the Centaur, 
 and south of Libra ; arid is so low down in the southern hemi- 
 sphere, that only a few stars in the group are visible to us. It 
 contains twenty-four stars, including three of the 3d magnitude, 
 and as many of the 4th ; the brightest of which, when on the 
 meridian, may be seen in a clear evening, just above the southern 
 horizon. Their particular situation, however, will be better 
 traced out by reference to the map than by written directions. 
 
 The most favorable time for observing this constellation is 
 toward the latter end of June. 
 
 HISTORY. 
 
 This constellation, according to fable, is Lycaon, king of Arcadia, who lived about CGOO 
 years ago, and was changed into a wolf by, Jupiter, because he offered human victims on 
 the altars of the god Pan. Some attribute this metamorphosis to another cause. The 
 Bins of mankind, as they relate, had become so enormous, that Jupiter visited the earth 
 to punish its wickedness and impiety. He came to Arcadia, where he was announced as 
 li god, and the people began to pay proper adoration to his divinity. Lycaon, however, 
 who used to Sacrifice all strangers to his wanton cruelty, laughed at the pious prayers 
 of his subjects, and to try the divinity of the god, served up human flesh on his table. 
 This impiety so offended Jupiter, that he immediately destroyed the house of Lycaon. 
 and changed him into a wolf. 
 
 " Of these he murders one ; he boils the flesh, 
 
 And lays the mangled morsels in a dish ; 
 
 Some part he roasts ; then serves it up so dress'd, 
 
 And bids me welcome to his human feast. 
 
 Moved with disdain, the table I o'erturned, 
 
 And with avenging flames the palace burn'd. 
 
 The tyrant in a fright for shelter gains 
 
 The neighboring fields, and scours along the plains: 
 
 Howling he fled, and fain he would have spoke, 
 
 But human voice his brutal tongue forsook. 
 
 His mantle, now his hide, with ragged hairs, 
 
 Cleaves to his back : a famish'd face he bears ; 
 
 His arms descend, his shoulders sink away 
 
 To multiply his legs for chase of prey: 
 
 He grows a wolf." Ovid. M<t. B. i. 
 
 TELESCOPIC OBJECTS. 
 
 1. a Lcpr A star with a distant companion, in the tail of Lupus ; R. A. 5h o **>ra, 
 40s. ; Dec. S. 17 56 5". A 3,^, pale yellow ; B 9%, grey. To find, draw a line fr^ra e 
 the central star of Orion's belt, through 6 and its nebulous patch on the sword, as low 
 down, and Sirius, and you meet a Lupi. 
 
 2. (3 LCHI A DOUBLE STAR; R. A. 5h. 21m. 23s. ; Dec. S. 20 53' 5". A 4, deep yel- 
 iow; B 11, blue. 
 
 S. y LCPI A wide TRIPLK STAR in a barren field; R. A. 5h. 87m. 48s.; Dec. 2C* 
 3l>' 2". A 4, light yellow ; B 6%, pale green ; C 18, dusky. A line from (5 Orionis through 
 the second cluster, and carried 16 beyond, falls upon it. 
 
 4. A bright STELLAR NKBCLA, of a milky white tinge ; R. A. 5h. 17m. 50s. Dec S. '24 
 89' 9". A fine object blazing towards the centre. 
 
 180. Situation of Lupus ? Number and magnitude of its stars? Best time to observe? 
 HISTORY. What was Lupus originally? Why changed and by whom? Described by 
 What poet? 
 TELESCOPIC OBJECTS. Alpha? Beta? Gamma? WhatNebulu? 
 
LIBRA. 91 
 
 LIBRA (THE SCALES). MAP IV. AND Y. 
 
 181. This is the seventh sign, and eighth constellation, from 
 the vernal equinox, and is situated in the Zodiac, next east of 
 Virgo. 
 
 The sun enters this sign, at the autumnal equinox, on the 23d 
 of September ; but does not reach the constellation before the 
 21th of October. 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 remembered that the xiyiK> 
 Aries and Libra, Cancer and Capricorn, and not the constellations of these names, are 
 meant: for the equinoxes are now in the constellations Pisces and Virgo, and the tropics 
 in Gemini and Sagittarius ; each constellation hating gone forward one isign in. tke 
 ecliptic. 
 
 About 22 centuries ago, the conMellution Libra coincided with the sign Libra; but 
 having advanced 30 or more in the ecliptic, it is now in the sign Scorpio, and the con- 
 stellation Scorpio is in the sign Sagittarius, and so on. 
 
 While Aries is now advanced a whole sign above the equinoctial point into north decli- 
 nation, Libra has descended as far below it into south declination. 
 
 182. Libra contains fifty-one stars, including two of the 2d 
 magnitude, two of the 3d, and twelve 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 northeast and southwest, and 
 having its upper and lower corners nearly in a line running north 
 and south. The two stars which form the N. E. side of the 
 square, are situated about 7 apart, and distinguish the Northern 
 Scale. The two stars which form the S. W. side of the square 
 are situated about 6 apart, and distinguish the Southern Scale. 
 
 Zubeneschamnli, in the Southern Scale, about 21 E. of Spi"-a, and 8 E. of Lambda 
 Virginis, is a star of the 2d magnitude, and is situated very near the ecliptic, about 42J^ 
 E. of the autumnal equinox. The distance from this star down to Theta Centauri ia 
 about 23, with which, and Spica Virginis, it forms a large triangle, on tlie right. 
 
 Zubenelgr'nwbi, the uppermost star in the Northern Scale, is also of the 2d magnitude, 
 9J^ above Zubeneschamali, toward the northeast, 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 11* 
 south of it. 
 
 Zubentuikrabi is a star of the 3d magnitude in the Northern Scale, 7 S. E. of Zubenel- 
 gemabi, and nearly opposite to Zubeneschamali, at the distance of 11 on the east. 
 These two make the diagonal of the square east and west. 
 
 Iota is a star of the 4th magnitude, and constitutes the souf ernmost corner of the 
 square. It is about 6 S. E. of Zubeneschamali, and 11 S. of Zuoenelgemabi, with which 
 it forms the other diagonal north and south. 
 
 Zebenelffubi is a star of the 3d magnitude, situated below the Southern Scale, at tho 
 
 181. Order and situation of Libra? What circumstance suggesting a balance? What 
 remarks respecting the distinction between the xigns and the constellations ? 182. Num- 
 ber of stars in Libra? Its mean declination? Right ascension? When on the meri- 
 dian? How may it be known? Describe the four stars. Closing remarks ? 
 
92 ASTRONOMY. 
 
 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 Virginia and Beta Scorpionis : and 
 comes to the meridian nearly at the same moment with Nekkar, in the head of Bootes. 
 
 The remaining btars in this constellation are too small to engage attention. 
 
 The scholar, in tracing out this constellation in the heavens, will perceive 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. 
 
 HISTORY. 
 
 Virgo was the goddess of justice, and Libra, the scales, which she is usually repre- 
 sented as holding in her left hand, are the appropriate emblem of her office. 
 
 The Libra of the Zodiac, says Maurice, in his Indian Antiquities, is perpetually seen 
 upon all the hieroglyphics of Egypt ; which is at once an argument of the great antiquity 
 of this asterism, and of the probability of its having ueen originally fabricated by the 
 astronoriical sons of Misraim. In some few zodiacs, Astrsca, or the virgin who holds the 
 balance in her hand as an emblem of equal justice, is not drawn. Such are the zodiacs 
 of Esne and Dendera. Humboldt is of opinion, that although the Romans introduced 
 *his constellation into their zodiao in the reign of Julius Caesar, still it might have been 
 used by the Egyptians and other nations of very remote antiquity. 
 
 It is generally supposed that the figure of the balance has been used by all nations to 
 denote the equality of the days and nights, at the period of the sun's arriving at this 
 sign. It has also been observed, that at this season there is a greater uniformity in th 
 temperature of the air all over the earth's surface. 
 
 Others affirm, that the beam only of the balance was at first placed among the stars, 
 and that the Egyptians thus honored it as their Nttometer, or instrument by which they 
 measured the inundations of the Nile. To this custom of measuring the waters of the 
 Nile, it is thought the prophet alludes, when he describes the Almighty as measuring 
 the waters in the hollow o/M-s hand. Isa. xl. 12. 
 
 The ancient husbandmen, according to Virgil, were wont to regard this sign as indi 
 eating the proper time for sowing their winter grain : 
 
 t " But when Astraea's balance, hung on high, 
 
 Betwixt the nights and days divides the sky, 
 Then yoke your oxen, sow your winter grain, 
 Till cold December comes with driving rain." 
 
 The Greeks declare that the balance was placed among the stars to perpetuate the 
 memory of Mochus, the inventor of weights and measures. 
 
 Those who refer the constellations of the Zodiac to the twelve tribes of Israel ascribe 
 the Balance to Asher. 
 
 TELESCOPIC OBJECTS. 
 
 1. a LIBRAE A wide DOUBLE STAR; R. A. 14h. 42m. 02s. ; Dec. S. 15 22' 3". A 8, pal* 
 yeilow; B 6, light grey. Carry a line from Arcturus to Spica; and from thence a rect- 
 angular one about 22 to the eastward. 
 
 2. ft LIBR..E A loose DOUBLE STAR; R. A. 15h. 08m. 24s. ; Dec. S. 8 47' 4". A 2%, pale 
 emerald ; B 12, light blue. 
 
 3. LIBRAE A fine TRIPLE STAR, between Libra and the right leg of Ophiuchus, 16 from 
 Antares, towards Serpentis ; R. A. 15h. 55m. 85s.; Dec. S. 10 55' 6". A 4 H, bright 
 white ; B 5, pale yellow ; C 7J<$, grey. Map VIII., Fig. 11. 
 
 4. A CLOSE CLUSTER, over the beam of the Scales ; R. A. 15h. 10m. 26s. ; Dec. N. 2 41' S". 
 A superb object, with a bright central blaze, and outlines in all directions. Map IX., 
 Fig. 51. Appears nebulous through small instruments. 
 
 5. A LARGE COMPRESSED CLUSTER of minute stars ; R. A. 15h. 08m. 06s. ; Dec. S. 20 26' 7*. 
 Faint and pale. 
 
 HISTORY. Who was Virgo, Ac.? Remark of Maurice ? What general supposition? 
 What other explanations? 
 IY.LESCOPIC OBJECTS. Alpha ? Beta? What triple star ? Map? Clusters and Map ? 
 
ERPENS. 93 
 
 SEEPED (THE SERPENT). PLATE Y. 
 
 183. There are no less than four kinds of serpents placed 
 among the constellations. The first is the Hydra, which is situ- 
 ated south of the Zodiac, below Cancer, Leo and Virgo ; the 
 econd is Hydrus, which is situated near the south pole; the 
 third is Draco, which is situated about the north pole ; and the 
 fourth is the serpent called Serpens Ophiuchi, and is situated 
 chiefly between Libra and Corona Borealis. A large part of 
 this constellation, however, is so blended with Ophiuchus, the 
 Serpent-Bearer, who grasps it in both hands, that the concluding 
 description of it will be deferred until we coine to that constel- 
 lation. 
 
 " The Serpens Ophiuchi winds his spire 
 Immense : fewer by ten his figure trace ; 
 One of the second rank ; ten shun the sight ; 
 And seven, he who bears the monster hides." 
 
 184. Those stars which lie scattered along for about 25, in a 
 serpentine direction between Libra and the Crown, mark the 
 body and head of the Serpent. 
 
 About 10 directly S. of the Crown there are three stars of 
 the 3d magnitude, which, with several smaller ones, distinguish 
 the head. * 
 
 185. Unuk, of the 2d magnitude, is the principal star in this 
 constellation. It is situated in the heart, about 10 below those 
 in the head, and may be known by its being in a line with, and 
 between, two stars of the 3d magnitude the lower one, marked 
 Epsilon, being 2^-, and the upper one, marked Delta, about 5^- 
 from it. The direction of this line is N. N. W. and S. S. E 
 Unuk may otherwise be known by means of a small star, just 
 above it, marked Lambda. 
 
 In that part of the Serpent which lies between Corona Borealis and the Scales, about 
 a dozen stars may be counted, of which five or six are conspicuous. 
 For the remainder of this constellation, the student is referred to Serpentarius. 
 
 "Vast as the starry Serpent, that on high 
 Tracks the clear ether, and divides the sky, 
 And southward winding from the Northern Wain. 
 Shoots to remoter spheres its glittering train." Statins. 
 
 HISTORY. 
 
 The Hivites, of the Old Testament, were worshipers of the Serpent, and were called 
 Ophites. The idolatry of these Ophites was extremely ancient, and was connected with 
 
 183. How many serpents among the constellations? Describe each. Which here 
 referred to? Is it fully described ? 184. What stars mark the body and head? 185. 
 Name the principal star. Where situated and how known ? 
 
 HISTORY What said of the Hivites? Tradition respecting Ophiuchus? Supposed 
 S.ripture reference? 
 
94 ASTRONOMY. 
 
 Siibfism-^ or the worship of the host of heaven. The heresy of the Ophites, mentioned 
 by Mosheim, in his Ecclesiastical H 'story, originated, perhaps, in the admission into the 
 Christian church of some remnant of the ancient and popular sect of Sabeists, who 
 adored the celestial Serpent. 
 
 According to ancient tradition, Ophiuchus is the celebrated physician 2Esculapius, son 
 of Apollo, who was instructed in the healing art by Chiron the Centaur; and the ser- 
 pent, which is here placed in his hands, is understood by some to be an emblem of his 
 sagacity and prudence; while othtis suppose it was designed to denote his skill in heal- 
 ing the bite of this reptile. Biblical critics imagine that this constellation is alluded to 
 in the following passage of the book of Job : 
 
 " By his spirit lie hath garnished the Heavens ; his hand hath formed the crooked ser- 
 pent." Mr. Green supposes, however, that the inspired writer here refers to Draco 
 because it is a more obvious constellation, being nearer the pole where the constellation, 
 were more universally noticed ; and moreover, because it is a more ancient constellation 
 than the Serpent, and the hieroglyphic by which the Egyptians usually represented the 
 heavens. 
 
 TELESCOPIC OBJECTS. 
 
 1. a SERPEXTIS ( UntiK) A star with a minute companion on the heart of the Serpent ; 
 R. A. I5h. 36m. 23s. ; Dec. N. 6" 55' 9". A 2^, pale yellow ; B 15, fine blue. An extremely 
 delicate object. 
 
 2. tf SKKPENTTS A delicate DOUBLE STAR in the Serpent's under jaw; R. A. 15h. 38m. 
 4Ss. ; Dec. N. 15" 55' 7'. A 3^, and B 10, both pale blue. 
 
 3. (5 SKRPKNTIS An elegant DOUBLE STAR in the bend of the neck ; R. A. 15h. 27m. 10s. ; 
 Dec. N. 11 04' 7". A 3, bright white ; B 5, bluish white. A fine object, about 5 N. W. 
 of Unak. 
 
 4. r] SBRPENTIS A star with a minute companion in the Serpent's body, nearly midway 
 between r/ Ophiuchi and C-Aquilae; R. A. 18h. 13m. 02s.; Dec. S. 2 56' 0". A 4, golden 
 yellow; B 13, pale lilac. A delicate and difficult object. 
 
 5. v SKRPENTIS A wide DOUBLE STAR in the middle of the Serpent, 4 northeast of rj \ 
 R. A. 17h. llm. 49s.; Dec. S. 12 40' 7"' A 4)$, pale sea-green; B 9, lilac, with a third 
 star in the field. 
 
 6. A delicate DOUBLE STAR; R. A. 15h. llm. 08s.; Dec. N. 2" 22' 6'. A 5^,pale yellow 
 B 10}$, light grey. Look 9 southwest of a Serpentis, 24 southeast of Arcturus. 
 
 CORONA BOREALIS (THE NORTHERN OKOWN). MAP V. 
 
 186. This beautiful constellation may be easily known by 
 means of its six principal 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 Ataroth, and by this namo 
 the stars in Corona Borealis are called, in the East, to this day. 
 
 187. Alphacca, 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 distinguished from the others both on account 
 of its position and superior brilliancy. Alphacca, Arcturus, and 
 Seginus, form nearly an isosceles triangle, the vertex of which is 
 at Arcturus. 
 
 TELESCOPIC OBJECTS. Alpha? Beta? Delta? Eta? Nu? &c. 
 
 186. How may Corona Borealis be known? Where situated? Its Hebrew namt-i 
 187. Describe Aiphacca? How distinguished ? What triangle ? 
 
CORONA BOREALIS. 95 
 
 188. This constellation contains twenty-one stars, of which 
 only six or eight are conspicuous ; and most of those are not 
 larger than the 3d 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 J uly. 
 
 "And, near to llelice, 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." 
 
 HISTORY. 
 
 This beautiful little cluster of stars is said to be in commemoration of a crown pre- 
 sented by Bacchus to Ariadne, the daughter of Minos, second king of Crete. Theseus, 
 king of Athens (1235 B. C.), was shut up in the celebrated labyrinth of Crete, to be 
 devoured by the ferocious Minotaur which was confined in that place, and which usually 
 fed upon the chosen young men and maidens exacted from the Athenians as a yearly 
 tribute to the tyranny of Minos; but Theseus slew the monster, and being furnished with 
 a clew of thread by Ariadne, who was passionately enamored of him, he extricated 
 himself from the difficult windings of his confinement. 
 
 He afterward married the beautiful Ariadne according to promise, and carried her 
 away ; but when he arrived at the island of Naxos, he deserted her, notwithstanding he 
 had received from her the most honorable evidence of attachment and endearing tender- 
 ness. Ariadne was so disconsolate upon being abandoned by Thesvus, that, as some say, 
 she hanged herself; but Plutarch say* that she lived many years after, and was espoused 
 to Bacchus, who loved her with much tenderness, and gave her a crown of seven stars 
 which, after her death, was placed among the stars. 
 
 " Resolves, for this the dear engaging dame 
 
 Should shine forever in the foils of fame; 
 
 And bids her crown among the stars be placed, 
 
 And with an eternal constellation graced. 
 
 The golden circlet mounts; and, as it flies, 
 
 Its diamonds twinkle in the distant skies; 
 
 There, in their pristine form, the gemray rays 
 
 Between Alcides and the Dragon blaze." 
 
 Manilius, in the first book of his Astronomicon, thus speaks of the Crown. 
 "Near to Bootes the bright crown is view'd, 
 
 \nd shines with stars of different magnitude: 
 
 Or placed in front above the rest displays 
 
 A vigorous light, and darts surprising rays. 
 
 This shone, since Theseus first his faith betray'd, 
 
 The monument of the forsaken maid." 
 
 \ 
 
 TELESCOPIC OBJECTS. 
 
 . a CORONA BOREALIS (Alphaccd) A bright star with a distant companion; R. A. 
 15h. 27m. 54s.; Dec. N. 27 15' 2". A 2, brilliant white; B 8, pale violet. 
 
 2. y CORONA BOREALIS A most difficult BINARY STAR, 2)3 from Alphacca; R. A. 15h. 
 80m. Ols. ; Dec. N. 26 48' 4"; with a distant companion. A 6, flushed white; B, uncer- 
 tain , C 10, pale lilac. 
 
 8. s COROX.* BOREALIS A fine DOUBLE STAR, 10* north and a Httle easterly frooi Alphacca ; 
 R. A 15h. 33m. 21s. ; Dec. N. 87" 09' 6". A 5, bluish white ; B 6, smalt blue A beauti- 
 ful object. 
 
 4. if COROS* BOREALIS A BINARY STAR, midway between the Northern Crown and the 
 club of Bootes ; R. A. 15h. 16m. 36s. ; Dec. N. 80' 52' 2". A north-northwest ray from a 
 C., rouse, through J, and half as far again, will hit it. A 6, white ; B 65$, golden yellow. 
 
 1S8. How many stars in this constellation? Their magnitudes? Mean declination 
 and right ascension ? 
 
 HISTORY. Story respecting Theseus and Arindne? 
 TELESCOPIC OBJECTS. Alpha? Oamina? Zeta? Eta? 
 
96 ASTRONOMY. 
 
 Sir John Herschel considered this the most remarkable binary star known, and the on'y 
 one that had completed a whole revolution since its discovery. Estimated period 432 
 vears. 
 
 URSA MINOR (THE LESSEE BEAE). MAP VI. 
 
 189. This constellation, though not remarkable in its appear 
 ance, and containing but few conspicuous stars, is, nevertheless, 
 justly distinguished from all others for the peculiar advantage 
 which its position in the heavens is well known to afford to nau- 
 tical astronomy, and especially to navigation and surveying. 
 
 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. Hence Ursa Minor will 
 be above or below, to the right or left of the pole star, accord- 
 ing to the hour ; as he makes the entire circuit from east to west 
 every 24 hours. 
 
 190. In all ages of the world, this constellation has been more 
 universally observed, and more carefully noticed than any other, 
 on account of the importance which mankind early attached to 
 the position of its principal star. This star, which is so near the 
 true pole of the heavens, ha* from time immemorial been deno- 
 minated the NORTH POLAR STAR. By the Greeks it is called 
 Cynosyrt ; by the Romans, Cynosura, and by other nations, 
 Alruccalah. In most modern treatises it bears the name of Po- 
 laris, or Alpha Polaris. 
 
 191 Polaris 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 toward Cas- 
 siopeia 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 joining Beta Cassio- 
 peiae, which lies at the distance of 32 on one side, and Megrez, 
 which lies at the same distance on the other, will pass through 
 the polar star. 
 
 Of the Pole Star Capt. Smyth observes : At present it is only 1 33' from the polar point, 
 ind by its northerly precession in declination will gradually approach to within 26' 30* 
 :>f it. This proximity to the actual pole will occur in A. D. 2095, but will not recur for 
 12,860 years. The period of the revolution of the celestial equinoctial pole about the 
 pole of the ecliptic, is nearly 26,000 years ; the north celestial pole, therefore, will be 
 vbout 13,000 years ; hence, nearly 49 from the present polar star. 
 
 189. For what is Ursa Minor distinguished ? What said of its situation and change of 
 position? 190. What said of the notice taken of it? Position of its principal star f 
 [ts Greek and Latin names, &c. ? 191. Describe Polaris? How found? lieoiar'is of 
 Capt. Smyth respecting? 
 
URSA MINOR 97 
 
 192. So general is the popular notion, that the North Polar 
 Star is the true pole of the world, that even surveyors and navi- 
 gators, who have acquired considerable dexterity in the use oi 
 the compass and the quadrant, are not aware that it ever had 
 any deviation, 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. 
 
 193. Hence, it is evident that the surveyor who regulates his 
 uompass by the North Polar Star, must take his observation 
 when the star is on the meridian, either above or below the pole, 
 or make allowance for its altered position in every other situa- 
 tion. For the same reason must the navigator, who applies 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 
 Idow the pole. 
 
 194. The method of finding the^ latitude of a place from the 
 altitude of the polar star, as it is very simple, 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 heavenly bodies, because a single observation, taken at any 
 hour of the night with a good instrument, will give the true lati- 
 tude, 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 
 the north pole of the earth, it would be easy to understand how latitude could be deter- 
 mined 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 elevatiun. Should the person 
 now travel one degree toward the north, he would see one degree below the star, and ht, 
 would think it had risen one degree. 
 
 And since we always see the whole of the upper hemisphere at one view, when there 
 ii, nothing in the horizon to obstruct our vision, it follows 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 in the 42d degree of north latitude we should, in like 
 manner, have our horizon just 42 below the pole, or the pole would appear to have an 
 elevation of 42. Whence we derive this general truth : The devotion of the pole of th& 
 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, is given in most treatises on the globe, 
 
 192. What popular error ? 193. When is the pole star a safe guide for the surveyor 
 or mariner? What allowances should be made by each? 194. What said of finding 
 the latitude by observations upon the pole star? What general rule stated? Whu"' 
 error ommitted ? 
 
#8 ASTRONOMY. 
 
 and as adopted by teachers generally, la to tell the scholar that the north pole ristj 
 higher and higher, as he travels farther and farther toward it. In oth' % r words, what- 
 ever number of degrees he advances toward 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 i* el&v<ited, but that our horizon, is 
 dtpretsxed as we advance toward the north. The same objection lies against the artifi- 
 cial globe; for it ought to be so fixe.l that the horizon might be raised or depressed, and 
 the pole remain in its own invariable position. 
 
 195. 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. 
 
 196. The first star in the handle, called Polaris, 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. 
 
 Koclmb may be easily known by its being the brightest and middle one of the three 
 conspicuous stars forming a row, one of which is about 2% and the other 3 from Kochab. 
 The two brighest of these are situated in the breast and shoulder of the animal, about 
 8" apart, and are called the Giuirdu 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. 
 
 197. 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 
 toward Gamma, in Cepheus ; but as they are continually chang- 
 ing their position in the heavens, they may be much better traced 
 out from the map, than from description. 
 
 Kochab is about 25 distant from Benetnasch, and about 24 
 from Dubhe, and hence forms with them a very nearly equi- 
 lateral triangle. 
 
 " The Lesser Bear 
 
 Leads from the pole the lucid band : the stars 
 \Vhich 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 I'OLAB rfTAK." 
 
 HISTORY. 
 
 The prevailing opinion is that Ursa Major and Ursa Minor are the nymph Calisto aiivl 
 her son Areas, *nd that they were transformed into bears by the enraged and imperious 
 Juno, and afterward translated to heaven by the favor of Jupiter, lest they might be 
 destroyed by the huntsmen. 
 
 The Chinese claim that the emperor Hong-ti, the grandson of Noah, hrst discovered 
 
 195. Number o* stars in Ursa Minor? Their magnitudes? How situated ? 196. De- 
 Bcnne Solaris. Kochab, and the Guards or Pointers? 197. Are all the stars distinctly 
 Visible? Direction? What triangle ? 
 
 HISTORY. What prevailing opinion, or myth? Chinese claim ? Phemcians? Greets 
 
URSA MINOR. 9U 
 
 the polar star, and applied it to purposes of navigation. It is certain that it was used 
 for this purpose in a very remote period of antiquity. From various passages in tb.8 
 ancients, it is manifest that the Phenicians steered by Cynosura, or the Lessor Bear; 
 vhereas, the mariners of Greece, and some other nations, steered by the Greater Bear, 
 called Helice, or Helix. 
 
 Lucan, a Latin poet, who flourished about the time of the birth of our Saviour, thiw 
 adverts to the practice of steering vessels by Cynosura : 
 
 " Unstable Tyre now knit to firmer ground, 
 With Sidon for her purple shells renown'd, 
 Safe in the Cynosure their glittering guide 
 With well-directed navies stem the tide." 
 
 ROWE'S Translation, B. iii. 
 
 The following extracts from other poets contain allusions to the same fact: 
 
 " Phenicia, spurning Asia's bounding strand, 
 By the bright Pole star's steady radiance led, 
 Bade to the winds her daring sails expand, 
 And fearless plough'd old Ocean's stormy bed." 
 
 MAURICE'S Elegy on Sir W. Jones, 
 
 " Ye radiant signs, who, from the ethereal plain 
 Sidonians guide, and Greeks upon the main, 
 Who from your poles all earthly things explore, 
 And never set beneath the western shore." 
 OVID'S Triatia. 
 
 " Of all yon multitude of golden stars, 
 Which the wide rounding sphere incessant bears. 
 The cautious mariner relies on none, 
 But keeps him to the constant pole alone." 
 
 LUCAN'S Pharsalia, B. viii. v. 225. 
 
 Ursa Major and Ursa Minor are sometimes called Triones, and sometimes the Greater 
 nnd Lesser Wains. In Pennington's Memoirs of the learned Mrs. Carter, we have the 
 following beautiful lines : 
 
 44 Here Cassiopeia fills-a lucid throne, 
 There, blaze the splendors of the Northern Crown ; 
 While the slow Car, the cold Triones roll 
 O'er the pale countries of the frozen pole : 
 Whose faithful beams conduct the wandering ship 
 Through the wide desert of the pathless deep." 
 
 Thales, an eminent geometrician and astronomer, and one of the seven wise men of 
 Greece, who flourished six hundred years before the Christian era, is generally reputed 
 to be the inventor of this constellation, and to have taught the use of it to the Phenician 
 navigators ; it is certain that he brought the knowledge of it with him from Phenice into 
 Greece, with many other discoveries both in astronomy and mathematics. 
 
 Until the properties of the magnet were known and applied to the use of navigation, 
 and for a long time after, the north polar star was the only sure guide. At what time the 
 attractive powers of the magnet were first known, is not certain ; they were known in 
 Europe about six hundred years before the Christian era ; and by the Chinese records, ft 
 is said that its polar attraction was known in that country at least one thousand years 
 earlier. 
 
 TELESCOPIC OBJECTS. 
 
 1. a URSJS MINORIS (Polaris) A DOUBLE STAR; R. A. Ih. 2m. 10s.; Dec. N. 88* 27' 4*. 
 A 2)$, topaz yellow ; B 9%, pale white: Map VIII., Fig. 1'J. 
 
 2. (3 URS.S MINORIS (ITochab) A star with a distant companion 4n the left shoulder; 
 R. A. 14h. 51m. 14s. ; Dec. N. 74 48' 2'. A 3, reddish ; B 11, pale grey several small 
 jtars in the field 
 
 3. d URS^E MIKORIS A star with a very distant telescopic companion in the middle of 
 (he tail of the figure ; R. A. 18h. 23m. 56s. ; Dec. N. 86 35' 4". A 8, greenish tinge ; 
 B 12, grey. 
 
 What proofs from the poets? What other names for Ursa Major and Ursa Minor? Wlm* 
 mid of Thales? Use of the pole star? The magnet? 
 
 OBJBCTS. Alpha? Show on li.e map, Beta Delta Epsil on Zeta. 
 
 5 
 
(00 ASTRONOMY. 
 
 4. e URS^B MAORIS A star with a minute companion, at the root of the tail ; R. A- 
 17h. 02m. 37s. ; Dec. N. 82 17' 01'. A 4, bright yellow; B 12, pale blue; three other 
 telescopic stars in the field. It is easily found, being the third star from Polaris 
 
 5. URS* MINORIS A DOUBLE STAR in the middle of the body ; R. A. 15h. 4'Jm. 52s. 5 
 Dec. N. 78 16' 07'. A 4, flushed white ; B 11, bluish with a yellow star of the 9th majj- 
 aitudc in the field. 
 
 CHAPTER IX. 
 
 CONSTELLATIONS ON THE MERIDIAN IN JULY. 
 
 SCORPIO (THE SCOEPION). MAP Y. 
 
 198. THIS is the eighth sign, and ninth constellation, in the 
 order of the Zodiac. It presents 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 east 
 ward 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. When astronomy was first cultivated in the East, the two 
 solstices and the two equinoxes took place when the sun was in Aquarius and Leo, Tau- 
 rus and Scorpio, respectively. 
 
 199. 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 distinguished from all others by the pecu- 
 liar luster and the position of its principal stars. 
 
 Antares is the principal star, and is situated in the heart of 
 the Scorpion, about 19 east of Zubenelgubi, the southernmost 
 star in the Balance. Antares is the most brilliant star in that 
 region of 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 reckoned 
 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 
 /cere much noticed by the astronomers of the East. 
 
 200. About sy northwest of Antares, is a star of the 2d 
 
 198. Order of Scorpio among the signs, Ac.? Its comparative interest? Situation? 
 When does the sun enter this sign ? When the constellation f How with the solstices 
 <vnd equinoxes anciently? Why not so now? 199. Number and magnitudes of the 
 cturs in Scorpio? How distinguished ? Name and position of its principal star? Hoy 
 Unown ? What use made of it ? What three other stars mentioned ? 200. What other 
 
SCORPIO. 101 
 
 magnitude, in the head of the Scorpion, called Graffias. It is 
 but one degree north of the earth's orbit. It may be recognized 
 by means of a small star, situated about a degree northeast 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 resembling in figure a boy's kite. 
 
 201. As you proceed from Antares, there are ten conspicuous 
 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 advance about 8 toward 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 magni- 
 tude. It is about 2 southeast of Antares, and is denoted by the Greek name of 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. 
 
 Jfu, of the 3d magnitude, is the 3d star from Antares. It is situated 4% below Epsi- 
 lon. It may otherwise be known by means of a small star close by it, on the left. 
 
 Zeta, 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 3J$ east of 
 Zeta. 
 
 Theta, of the same magnitude, is the sixth star from Antares, and about 4^' east 
 of Eta. Here, the line turns again, curving to the north, and terminates in a couple 
 of stars. 
 
 Iota is the seventh star from Antares, 3 %* above Theta, curving a little 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. 
 
 LesittJi, 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. 
 
 202. 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 constellations may be so accurately 
 delineated, as to preclude everything like uncertainty in the 
 knowledge 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." 
 
 HISTORY. 
 
 This sign was anciently represented by various symbols, sometimes by a snake, and 
 bometimes by a crocodile ; but most commonly by the scorpion. This last symbol is 
 
 Rtar described ? Size and position? How recognized? What said of the broad part or 
 body of Scorpio? 201. What stars form the tail of Scorpio? Are they conspicuouo ? 
 Name and describe in detail? 202. General remarks respecting this constellation? 
 JlrSTOUY. How was Scorpio anciently delineated? How regarded by ancient astro'.o 
 
102 ASTRONOMY. 
 
 found on the Mithraic monuments, which is pretty good evidence that these monuments 
 yere constructed when the vernal equinox accorded with Taurus. 
 
 On f )oth the zodiacs of Dendera, there are rude delineations of this animal ; that on 
 the portico differs considerably from that on the other zodiac, now in the Louvre. 
 
 Scorpio was considered by the ancient astrologers as a sign accursed. The Egyptians 
 Qxed the entrance of the sun into Scorpio as the commencement of the reign of Typhon, 
 when the Greeks fabled the death of Orion. When the sun was in Scorpio, in the month 
 of Atkyr, as Plutarch informs us, the Egyptians inclosed the body of their god Osiris in 
 an ark, or chest, and during this ceremony a grt-at annual festival was celebrated. 
 Three days after the priests had inclosed Osiris in the ark, they pretended to have found 
 him again. The death of Osiris, then, was lamented when the sun in Scorpio descended 
 to the lower hemisphere, and when he arose at the vernal equinox, then Osiris was said 
 to be born anew. 
 
 The Egyptians or Chaldeans, who first arranged the Zodiac, might have placed Scorpio 
 in this part of the heavens to denote that when the sun enters this sign, the diseases 
 Incident to the fruit season would prevail ; since Autumn, which abounded in fruit, often 
 brought with it a great variety of diseases, and might be thus fitly represented by that 
 venomous animal, the scorpion, who, as he recedes, wounds with a sting in his tail. 
 
 Mars was the tutelary deity of the Scorpion, and to this circumstance is owing all that 
 largon of the astrologers, who say that there is a great analogy between the malign 
 influence of the planet M>rs and this sign. To this also is owing the doctrine of the 
 alchemists, that iron, which metal they call Mars, is under the dominion of Scorpio ; so 
 ibat the transmutation of it into gold can be effected only when the sun is in this sign. 
 
 The constellation of the Scorpion is very ancient. Ovid thus mentions it in his beau- 
 tiful fable of Phaeton : 
 
 " There is a place above, where Scorpio bent, 
 In tail and arms surrounds a vast extent ; 
 In a wide circuit of the heavens he shines, 
 And fills the place of two celestial signs." 
 
 According to Ovid, this is the famous scorpion which sprang out of the earth at the 
 command of Juno, and stung Orion ; of which wound he died. It was in this way the 
 imperious goddess chose to punish the vanity of the hero and the hunter, for boasting 
 that there was not on earth any animal which he could not conquer. 
 
 " Words that provoked the gods once from him fell, 
 'No beasts so fierce,' said he, 'but I can quell;' 
 When lo ! the earth a baleful scorpion sent, 
 To kill Latona was the dire intent ; 
 Orion saved her, though himself was slain, 
 But did for that a spacious place obtain 
 In heaven : ' to tiiee my life,' said she, ' was dear, 
 And/or thy merit shine illustrious tliere" 
 
 Although both Orion and Scorpio were honored by the celestials with a place amonp 
 the stars, yet their situations were so ordered that when one rose the other should set, 
 and viee versa; so that they never appear in the same hemisphere at the same time. 
 
 In the Hebrew zodiac this sign is allotted to Dan, because it is written, " Dan shall be 
 a serpent by the way, an adder in the path." 
 
 TELESCOPIC OBJECTS. 
 
 1- n SCORFII (Antares) A bright star with a companion in the heart of Scorpio ; R. A 
 16h. 19m. 36s. ; Dec. S. 26 04' 8". A 1, fiery red ; B 8, pale. Very dose. 
 
 2. SCORPII (Grajfias) A star with a companion in the head; R. A. 15h. 56m. 08s.* 
 Dec. S. 19 21' 7". A 2, pale white ; B 5 J$, lilac tinge. 
 
 8. v SCOBPII A neat DOUBLE STAR, east by north from about 2" ; R. A. ioh. 02m. 42s. 
 Oec. S. 19 02' 8*. A 4, bright white ; B 7, pale lilac. Professor Mitchell registers this 
 AS a triple star. 
 
 4. a SCORPII A delicate DOUBLE STAR in the body of the figure; R. A. 16h. lira. 28s.; 
 
 gers ? Egyptian myth respecting Typhon, &c. ? Supposed reason why Scorpio was placed 
 where it u? Why do astrologers connect Mars with Scorpio ? The Alchemists? Wha*, 
 poetic proof of the itiquity of Scorpio? Ovid's myth respecting ? Relative position of 
 Orion and Scorpio.' 1 '<vce of Scorpio in the Hebrew Zodiac, and why? 
 
 TKLSSCOPIC OBJECTS. Alpha? Beta? Nu? Sigma? Whatcluster? Point out on the 
 nap. What Nebula ? 
 
HERCULES. 103 
 
 lec. b. 26* 12' 2*. About 2* west by north of Antares. A 4, creamy white; B 9H 
 lilac tint. 
 
 5. A COMPRESSED GLOBULAR CLUSTER in the right foot of Ophiuchus, or the Scorpion'? 
 back ; R. A. 16h. 07m. 28s. ; Dec. S. 22 35' 4". Half way between a and ,<3 Scorpii, or V 
 east of (5. A fine bright object, in an open space, with a few telescopic stars in the 
 field. Pronounced by Herschel " the richest and most condensed mass of stars which 
 the firmament can offer to the contemplation of astronomers." Map IX., Fig". 52. 
 
 6. A compressed mass of very small stars, in the middle of the body, with outlay re, 
 and a few stellar companions in the field ; R. A. 16h. 13m. 51s. ; Dec. S. 26 07' 5'. It is 
 l% west of Antares. Elongated and bright in the center. 
 
 7. A fine large RESOLVABLE NEBULA at the root of the tail, about 7 southeast from 
 Antares ; R. A. 16h. 51m. 04s. ; Dec. S. 29 50' 6". A mass of small stars running up to a 
 blaze in the center has been mistaken for a comet. 
 
 HERCULES. MAP V. 
 
 203. Hercules is represented on the map invested with the 
 skin of the Nemaean Lion, holding a massy club in his right 
 hand, and the three-headed dog Cerberus in his left. He occu 
 pies a large space in the northern hemisphere, with one foot rest- 
 ing on the head of Draco, on the north, and his head nearly 
 touching that of Ophiuchus, on the south. This constellation 
 extends from 12 to 50 north declination, and its mean right 
 ascension, is 255 ; consequently its centre is on the meridian 
 about the 21st of July. 
 
 204. Hercules is bounded by Draco on the north, Lyra on the 
 east, Ophiuchus or the Serpent-Bearer on the south, and the Ser- 
 pent and the Crown on the west. It contains one hundred and 
 thirteen stars, including one of the 2d, or of between the 2d and 
 3d magnitudes, nine of the 3d magnitude, and nineteen of the 
 4th. The principal star is Ras Algethi, and is situated in the 
 head, about 25 southeast of Corona Borealis. It may be 
 readily known by means of another bright star of equal magni- 
 tude, 5 east-southeast of it, called Ras Alhague. Ras Alhague 
 marks the head of Ophiuchus, and Ras Algethi that of Her- 
 cules. These two stars are always seen together like the bright 
 pairs in Aries, Gemini, the Little Dog, &c. They come to our 
 meridian about the 28th of July, near where the sun does the 
 last of April, or the middle of August. 
 
 About midway between Ras Algethi on the southeast, and Ariadne's Crown on t,ie 
 northwest, may be seen Beta and Gamma, two stars of the 3d magnitude, situated in 
 the west shoulder, about 3 apart. The northernmost of these two is called RifUUdU, 
 
 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. 
 
 203. Describe Hercules? His magnitude and position? When on the meridian Y 
 204. How bounded ? Number of stars ? Their size ? Principal star, and how knowu ? 
 What said of Ras Alhague, and Ras Algethi ? Of Beta aud Gamma ? 
 
104 ASTRONOMY. 
 
 205. About 12 E. N. E. of Rutilicus, and 10 directly north o 
 Has 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 Her 
 cules, with Ras Algethi 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 ro\v, 
 8 and 4 apart, extei ding from the shoulder, in a northeasterly direction. That small 
 cluster, situated in a triangular form, about 14" northeast of Ras Algethi, and 18* east- 
 eoutheast 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, 
 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, maybe known by means of one or two other small stars, 
 close by it, on the east. Eta, in the northwest corner, may be known by its being in a 
 row with two smaller stars, extending toward the northwest, and about 4 apart. The 
 stars of the 4th magnitude, just south of the Dragon's head, point out the left foot and 
 ankle of Hercules. 
 
 Several other stars, of the 3d and 4th magnitudes, may be traced out in this constella- 
 tion, by reference to the map. 
 
 HISTORY. 
 
 This constellation is intended to immortalize the name of Hercules, the Theban^ so 
 celebrated in antiquity for his heroic valor and invincible prowess. According to the 
 ancients, there were many persons of this name. Of all these, the son of Jupiter and 
 Alcmena is the most celebrated, and to him the actions of the others have been gene- 
 rally attributed. 
 
 The birth of Hercules was attended with many miraculous events. He was brought 
 up at Tirynthus, or at Thebes, and before he had completed his eighth month, the jealousy 
 of Juno, who was intent upon his destruction, sent two snakes to devour him. Not ter- 
 rified at the sight of <he serpents, he boldly seized them, and squeezed them to death, 
 while his brothei Iphicles alarmed the house with his frightful shrieks. 
 
 He was early instructed in the liberal arts, and soon became the pupil of the centaur 
 Chiron, under whom he rendered himself the most valiant and accomplished of all the 
 heroes of antiquity. In the 18th year of his age, he commenced his arduous and glorious 
 pursuits. He subdued a lion that devoured the flocks of his supposed father, Amphi- 
 tryon. After he had destroyed the lion, he delivered his country from the annual tri- 
 bute of a hundred oxen, which it paid to Erginus. 
 
 As Hercules, by the will of Jupiter, was subjected to the power of Eurystheus, and 
 obliged to obey him in every respect, Eurystheus, jealous of his rising fame and power, 
 ordered him to appear at Mycenae, and perform the labors which, by priority of birth, 
 he was empowered to impose upon him. Hercules refused, but afterwards consulted 
 the oracle of Apollo, and was told that he must be subservient, for twelve years, to the 
 will of Eurystheus, in compliance with the commands of Jupiter; and that, after he had 
 achieved the most celebrated labors, he should be reckoned in the number of the gods. 
 So plain an answer determined him to go to Mycenae, and to bear with fortitude what- 
 ever gods or men should impose upon him. Eurystheus, seeing so great a man totally 
 subjected to him, and apprehensive of so powerful an enemy, commanded him to achieve 
 a number of enterprises the most difficult and arduous ever known, generally called the 
 TWELVE LABORS OF HKRCULES. Being furnished with complete armor by the favor of the 
 gods, he boldly encountered the imposed labors. 
 
 1. He subdued the Nemaean Lion in his den, and invested himself with his skin. 
 
 2. He destroyed the Lernaean Hydra, with a hundred hissing heads, and dipped his 
 arrows in the gall of the monster, to render their wounds incurable. 
 
 8. He took alire the stag with golden horns and brazen feet, so famous for its incre- 
 dible swiftness, after pursuing it for twelve months, and presented it, unhurt, to 
 Eurystheus. 
 
 4. He took alive, the Erymanthian Boar, and killed the Centaurs who opposed him. 
 
 2<>5. What two other stars, and what triangle? How trace the left or east arm of Her- 
 cules? What four stirs, and forming what? Describe Pi, and how known. Eta? Any 
 other stars? 
 
 HISTORY. Design of tMs constellation ? Story of the birth of Hercules ? His wondt:i fu 
 
HERCULES. 105 
 
 5. He cleansed the stables of Augias, in which 3,000 oxen had been confined for many 
 years. 
 
 6. He killed the carnivorous birds which ravaged the country of Arcadia, and fed on 
 human flesh. 
 
 7. He took alive, and brought into Peloponnesus, the wild bull of Crete, which no 
 mortal durst look upon. 
 
 8. He obtained for Eurystheus the mares of Diomedes, which fed on human flesh after 
 having given their owner to be first eaten by them. 
 
 9. He obtained the girdle of the queen of the Amazona, a formidable nation of warlike 
 f- -rr>,les. 
 
 10. He killed the monster Geryon, king of Gades, and brought away his numerous 
 flocks, which fed upon human flesh. 
 
 11. He obtained the golden apples from the garden of the Hesperides, which were 
 * \tchcd by a dragon. 
 
 "2. And finally, he brought up to the earth the three-headed dog Cerberus, the guar- 
 dian of the entrance to the infernal regions. 
 
 According-to Dupuis, the twelve labors of Hercules are only a figurative representation 
 of the annual course of the sun through the twelve signs of the Zodiac ; Hercules being put 
 for the sun, inasmuch as it is the powerful planet which animates and imparts fecundity 
 to the universe, and whose divinity has been honored, in every quarter, by temples and 
 altars, and consecrated in the religious strains of all nations. 
 
 Thus Virgil, in the eighth book of his JSneid, records the deeds of Hercules, and eele 
 brates his praise : 
 
 " The lay records the labors, and the praise, 
 
 And all the immortal acts of Hercules. 
 
 First, how the mighty babe, when swath'd in bands, 
 
 The serpents strangled with his infant hands ; 
 
 Then, as in years and matchless force he grew, 
 
 The (Echalian walls and Trojan overthrew, 
 
 Besides a thousand hazards they relate, 
 
 Procured by Juno's and Eurystheus' hate. 
 
 Thy hands, unconquer'd hero, could subdue 
 
 The cloud-born Centaur, and the monster crew; 
 
 Nor thy resistless arm the bull withstood ; 
 
 Nor he, the roaring terror of the wood. 
 
 The triple porter of the Stygian seat 
 
 With lolling tongue lay fawning at thy feet, 
 
 And, seized with fear, forgot the mangled meat. 
 
 The infernal waters trembled at thy sight: 
 
 Thee, god, no face of danger could affright; 
 
 Nor huge Typhaeus, nor the unnumber'd snake, 
 
 Increased with hissing heads, in Lerna's lake." 
 
 Besides these arduous labors which the jealousy of Eurystheus imposed upon him, ne 
 also achieved others of his own accord, equally celebrated. Before he delivered himself 
 up to the king of Mycenze he accompanied the Argonauts to Colchis. He assisted the 
 gods in their wars against the giants, and it was through him alone t>at Jupiter obtained 
 the victory. He conquered Laomedon and pillaged Troy. 
 
 At three different times he experienced fits of insanity. In the second, he slew the 
 brother of his beloved lole ; in the third he attempted to carry away the sacred tripod 
 from Apollo's temple at Delphi, for which the oracle told him he must be sold as a sla^e. 
 He was sold accordingly to Omphale, que^n of Lydia, who restored him to liberty, and 
 married him. After this he returned to Peloponnesus, and re-established on the throne 
 of Sparta his friend Tyndarus, who had been expelled by Hippocoon. He became 
 enamored of Dejanira, whom, after having overcome all his rivals, he married: but wa? 
 obliged to leave his father-in-law's kingdom, because he had inadvertently killed a man 
 with a blow of his fist. He retired to the court of Ceyx, king of Trachina, and in his 
 way was stopped by the streams of the Evenus, where he slew the Centaur Nessus, for 
 
 E resuming to offer indignity to his beloved Dejanira. The Centaur, on expiring, gave to 
 ejanira the celebrated tunic which afterward caused the death of Hercules. "This 
 tunic," said the expiring monster, " has the virtue to recall a husband from unlawful 
 love." Dejanira, fearing lest Hercules should relapse again into love for the beautifui 
 lole, gave him the fatal tunic, which was so infected with the poison of the Lernsean 
 
 exploits ? Origin and character of the twelve labors ? What are these labors supposed 
 to represent? What quotation from Virgil ? Story of the death of Hercules? Ovid * 
 
i06 ASTRONOMY. 
 
 Hydra, tnat he had no sooner invested himself with it, than it began tc penetrate his 
 hones, and to boil through all his veins. He attempted to pull it off, but it was too lato. 
 " As the red iron hisses in the flood, 
 So boils the venom in his curdling blood. 
 Now with the greedy flame his entrails glow, 
 And livid sweats down all his body fir/* 
 The crackling nerves, burnt up, are burst in twain, 
 The lurking venom melts his swimming brain." 
 
 As the distemper was incurable, he implored the protection of Jupiter, gave his bow 
 and arrows to Philoctetes, and erected a large burning pile on the top of Mount (Eta. 
 He spread on the pile the skin of the Nemaean lion, and laid himself down upon it, as on 
 a bed, leaning his head upon his club. Philoctetes set fire to .the pile, and the hero saw 
 himself, on a sudden, surrounded by the most appalling flames; yet he did not betray 
 any marks of fear or astonishment. Jupiter saw him from heaven, and told the sur- 
 rounding gods, who would have drenched the pile with tears, while they entreated tt it 
 he would raise to the skies the immortal part of a hero who had cleared the earth frcm 
 BO many monsters and tyrants ; and thus the thunderer spake : 
 
 " Be all your fears forborne : 
 
 The (Etean fines do thou, great hero, scorn. 
 
 Who vanquish'd all things shall subdue the flame 
 
 That part alone of gross maternal frame 
 
 Fire shall devour ; while what from me he drew 
 
 Shall live immortal, and its force subdue : 
 
 That, when he's dead, I'll raise to realms above , 
 
 May all the powers the righteous act approve." 
 
 Ovid's Met. lib. ix. 
 
 Accordingly, after the mortal part of Hercules was consumed, as the ancient poets 
 say, he was carried up to heaven in a chariot drawn by four horses. 
 
 " Quern pater omnipotens inter cava nubila raptum, 
 Quadrijugo curru radiantibus intulit astris." 
 
 " Almighty Jove 
 
 In his swift car his honor'd offspring drove ; 
 High o'er th e hollow clouds the coursers fly, 
 And lodge the hero in the starry sky." 
 
 Ovid's Met. lib. ix. v. 271. 
 
 TELESCOPIC OBJECTS. 
 
 1. a HBRCULIS (Ras AlgetM)A beautiful IX>UBLE STAB in the head of Hercules ; R. A. 
 J7h. 07m. 21s. ; Dec. N. 14 34' 05". A 3J^, orange ; B 5^, greenish. Map VIII., Fig. 13. 
 
 2. (3 HBRCCLIS (Rutibicus) A fine DOUBLE STAB in a barren field, on the hero's left 
 Shoulder ; R. A. 16h. 23m. 21s. ; Dec. N. 21 50' 6". A 2}, pale yellow; B 11, lilac tint. 
 
 8. 7 HERCULIS An open DOUBLE STAB in a dark field, on the left arm; R. A. 16h. 14m. 
 63s.; Dec. N. 19 32' 0". A3j, silvery white ; BIO, lilac. About half-way from .Baa 
 Algethi, in the head, to Alphaeca in the Northern Crown. 
 
 4. 6 HERCULIS A BINART STAB on the right shoulder, and about 11 due north of a- 
 R. A. 17h. 08m. 28s.; Dec. N. 25 01' 9". A 4, greenish white; B S%, grape red. It 
 forms an equilateral triangle with a and 13. 
 
 5. C HERCULIS A close BINARY STAB over the middle of the body ; R. A. 16h. 85m. 15s. , 
 Dec. N. 31 53' 7". A3, yellowish white; B 6, orange tint. A " wonderous object" 
 one star being sometimes occulted by the other. 
 
 6. 77 HEBCULIS A bright star with a distant companion on the left thigh ; R. A. 16h. 
 87m. 25s. ; Dec. N. 39 13' 8". A 3, pale yellow ; B 10, dusky. 
 
 7. A LARGE CLUSTER on the left thigh, between and rj, 5%' southwesterly of the 
 latter; R. A. 16h. 35m. 58s. ; Dec. N. 36 45' 8". A superb object, blazing up in the cen- 
 ter, with numerous outlayers. Map IX., Fig. 53. May be seen by the naked eye in the 
 absence of the moon. 
 
 8. A GLOBULAR CLUSTER of minute stars 1% north by east of f] ; R. A. 17h. 12m. 14s . 
 Dec. N. 43 18' 4". Large, bright, and resolvable, with a luminous centre. Several 
 other stars in the field. Map IX., Fig. '54. 
 
 TELV.SCOPIC OBJECTS. Alpha ? Point out on the map Beta? Gamma? Delta? Zeta/ 
 Eta? What clusters? Point out on the map. What Nebula? 
 
SERPENTARIUS. 107 
 
 9. A small PLANETARY NEBULA between the hero's shoulders ; R. A. 16h. 37m. 46g. ; Deo. 
 9A 05' 8*. A curious object, with a disc 8" in diameter. Look northeast of y and /3 
 in the left arm, to a point forming an equilateral triangle with these two stars. 
 
 10. A fine PLANETARY NEBULA near the right knee of Hercules; R. A. 16h. 43m. 28s. 
 Dec. N. 46 47' 0". About 4 east by north from T. It is large, round, and of a lucid 
 pa-e blue hue. A 6th magnitude star near it somewhat eclipses its brightness 
 
 SERPENTARIUS, VEL OPHIUCHUS (THE SERPENT BEAEEE). 
 MAP V. 
 
 206. THE SERPENT-BEARER is also called JSsculapius, or the 
 god of medicine. He is represented as a man with a venerable 
 beard, 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- 
 heaven, directly south of Hercules, and west of Taurus Pouia- 
 towski. Its center is very nearly over the equator, opposite to 
 Orion, and comes to the meridian the 26th of July. It contains 
 seventy-four stars, including one of the 2d magnitude, five of 
 the 3d, and ten of the 4th. 
 
 207 The principal star in Serpentarius is called Ras Alhague, 
 It is of the 2d magnitude, and situated in the head, about 5 
 E. S. E. of Ras Algethi, in the head of Hercules. Has Alhague 
 is nearly 13 N. of the equinoctial, while Rho, 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 S. W. of Ras Alhague are two small stars 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 S. S. E. of Ras Alhague are two other stars of the 3d magni- 
 tude, in the east shoulder, and about 2* apart. The upper one is called Cheteb, and the 
 lower one Gamma. These stars in the head and shoulders of Serpentarius, form a tri- 
 angle, with the vertex in Ras Alhague, and pointing toward the northeast. 
 
 208 About 4 E. of Gamma, is a remarkable cluster of four 
 or five stars, in the form of the letter Y, with tne open part to 
 the north. It very much resembles the Hyades. This beautiful 
 little group mark the face of TAURUS PONIATOWSKI. The solsti- 
 tial colure passes through the equinoctial about 2 E. of the 
 
 206. What other name has the Serpent Bearer? How represented? Situation and 
 extent? Number and size of its principal stars? 207. Name of its principal star* 
 M-ignitude and situation? Rho, and its situation? Use of these two stars? What said 
 of Iota and Kappa? Of Chelcb and Gamma? 208. What remarkable cluster? Fn 
 
 5* 
 
108 ASTRONOMY. 
 
 lower star in the vertex of the Y. The letter name of this 
 star is k. , 
 
 There is something remarkable in its central position. It is situated almost exactly fn 
 the mid-heavens, being nearly equidistant from the poles, and midway between the ver- 
 nal and autumnal equinoxes. It is, however, 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 half-way 
 between, and nearly in a line with, the two in the hand and the two in the shoulder, ie 
 another star of the 3d magnitude, marked Zeta, situated in the Serpent, opposite the 
 right elbow. It may be known by means of a minute star just under it. 
 
 Marsic, in the left arm, is a star of the 4th magnitude, about 10 S. W. of Iota and 
 Kappa. About 7* farther in the same direction are two stars of the 3d magnitude, situ- 
 ated in the hand, and a little more than a degree apart. The upper one of the two, 
 which is about 16 N. of G raffias in Scorpio, is called Yed; the other is marked Epsilon. 
 These two stars mark the other point in the folds of the monster where it is grasped by 
 Serpentarius. 
 
 The left arm of S-irpentarius may be easily traced by means of the two stars in the 
 shoulder, the one (Marsic) near the elbow, and the two in the hand; all lying nearly 
 in a line N. N. E. and S. S. W. 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 inclining a little to the east, by Zeta, 
 (known by a little star right under it,) and then by the two small ones in the right hand, 
 situated about 6 below Zeta. 
 
 About 12* from Antarcs, 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 
 8d and 4th magnitudes, and marked Rho. There are several other stars in this constel- 
 lation of the 3d and 4th magnitudes. They may be traced out from the maps. 
 
 " Thee, Serpentarius, we behold distinct, 
 With seventy-four refulgent stars ; and one 
 Graces thy helmet, of the second class : 
 The Serpent, in thy hand grasp'd, winds his spire 
 Immense ; fewer by ten his figure trace ; 
 One of the second rank ; ten shun the sight; 
 And seven, he who bears the monster hides." Eudosia. 
 
 HISTORY. 
 
 This constellation was known to the ancients twelve hundred years before the Chris- 
 tian era. Homer mentions it. It is thus referred to in the Astronomicon of Manillas '- 
 " Next, Ophiuchus strides the mighty snake, 
 Untwists his winding folds, and smooths his back, 
 Extends his bulk, and o'er the slippery scale 
 His wide-stretch'd hands on either side prevail 
 The snake turns back his head and seems to rage : 
 That war must last where equal power prevails." 
 
 JEsculapius was the son of Apollo, by Coronis, and was educated by Chiron the Ceii- 
 taur in the art of medicine, in which he became so skilful, that he was considered the 
 inventor and god of medicine. At the birth of -.Esculapius, the inspired daughter of 
 Chiron uttered, " in sounding verse " this prophetic strain. 
 
 " Hail, great physician of the world, all hail ! 
 Hail, mighty infant, who, in years to come, 
 Shall heal the nations and defraud the tomb! 
 Swift be thy growth ! thy triumphs unconfined ! 
 Make kingdoms thicker, and increase mankind : 
 Thy daring art shall animate the dead, 
 And draw the thunder on thy guilty head : 
 Then shalt thou die, but from the dark abode 
 Rise up victorious, and be twice a god." 
 
 and resemblance? Marks what? What said of the lower star in the V.? What stars 
 Bouth of it ? What c f Marsic ? Of Yed and Epsilon ? How trace the left arm ? 
 
 HISTORT. Antiquity of this constellation ? Proof? Who was JEsculapius ? Account 
 of his great skill ? His metamorphosis ? Remarkable fact respecting Socrates and Plato ' 
 
SERPENT ARIL'S. 109 
 
 He accompanied the Argonauts to Colchis, in the capacity of physician. He is said to 
 ttave restored many to life, insomuch that Pluto complained to Jupiter, that hia dark 
 dominion was in danger of being depopulated by his art. 
 
 JSsculapius was worshiped at Epidaurus, a city of Peloponnesus, and hence he is 
 styled by Milton " the god in Epidaurus." Being sent for to Rome in the time of a plague, 
 he assumed the form of a serpent and accompanied the ambassadors, but though thus 
 changed, he was -flSscuiapius still, in serpente deus the deity in a serpent and under 
 that form he continued to be worshiped at Rome. The cock and the serpent were sacred 
 to him, especially the latter. The ancient physicians used them in their prescriptions. 
 
 One of the last acts of Socrates, who is accounted the wisest and best man of Pagan 
 antiquity, was to offer a cock to 2Esculapius. He and Plato were both idolaters ; they 
 conformed, and advised others to conform, to the religion of their country ; to gross 
 fdolatry and absurd superstition. If the wisest and most learned were so blind, what 
 must the foolish and ignorant have been ? 
 
 TELESCOPIC OBJECTS. 
 
 1. a OPHIUCHI (Ras Alhague) A bright star with a minute companion, in tne head of 
 the figure ; R. A. ITh. 27m. 30s. ; Dec. N. 12 40' 08". A 2, sapphire ; B 9, pale grey. A 
 coarse triplet of small stars near them. 
 
 2. 6 OPHIUCUI (Yed) A star with a distant companion, in the right hand ; R. A. 16h. 
 05in. 58s. ; Dec. S. 3 16' 07". A 3, deep yellow ; B 10, pale lilac ; a third minute star in 
 the field. 
 
 3. 7) OPHIUCHI A brilliant star with a distant companion, on the left knee ; on the 
 margin of the milky way ; R. A. 17h. Olm. 13s. ; Dec N. 15 81' 03". A 2J$, pale yellow ; 
 B 13, blue. 
 
 4. T OPHIUCHI A close BINARY STAR on the left hand, 15* northeast of the bright star 
 17, just described, towards Altair ; R. A. 17h. 54m. 22s. ; Dec. S. 8" 10' 04". A 5, and B 
 6- both pale white ; C 10, light blue ; two other stars in the field. Out of place on the 
 map, or R. A. wrong in the tables, as given above. 
 
 5. A TRIPLE or rather MULTIPLE STAR, between the left foot of Ophiuchus, and the root of 
 the tail of Scorpio ; R. A. 17h. 05m. 29s. ; Dec. S. 26 21' 05". It is about 10" due east of 
 Antares. A 433, ruddy; B 6%, pale yellow; 7J4, greyish. The latter is double, a 
 minute companion appearing at a distance, though not seen through ordinary instruments. 
 For relative position, &c., see Map VIII., Fig. 14. 
 
 6. A fine GLOBULAR CLUSTER, between the right hip and elbow ; R. A. 16h. 38m 56s. ; 
 Dec. S. 1 40' 03". A rich cluster, condensed towards the center, ,with many straggling 
 outlayers. About 8* from Ophiuchi, towards ft. 
 
 T. A RICH CLUSTER of compressed stars, in the right hip ; R. A. 16n. 48m. 45s. ; Dec. S. 
 3 51' 08". About 8* east of e Ophiuchi; or half-way between /3 Librae, and a Aquilae. A 
 oeautiful round cluster, and may be seen with a telescope three feet in length. 
 
 8. A BOUND CLUSTER on the left leg ; R. A. ITh. 09m. 42s. ; Dec. S. 18 20' 07'. It lies 
 about 3 southeast of , and rather more than % the distance on a line from Antares tc 
 Altair. A fine object myriads of stars clustering to a blaze in the center. 
 
 9. A LARGE GLOBULAR CLUSTER in the left arm ; R. A. lib. 29m. 13s. ; Deo. S. 3' 09' 01'. 
 It lies 16 south of Ras Alhague, or about half way from Scorpii to t Aquilae. 6%* south- 
 ty-west of y Ophiuchi. A fine object, of a lucid white, and may be seen with small instru- 
 aicnts. Several stars in the field. Map IX., Fig. 55. 
 
 TBLESCOPIC OBJECTS. Alpha? Delta? Eta? What multiple star? Point out on the 
 nap. What clusters ? Which shown on the map? 
 
1 1 ASTRONOMY. 
 
 CHAPTER X. 
 
 CONSTELLATIONS ON THE MERIDIAN IN AUGFHT. 
 
 DRACO (THE DEAGON). MAP VL 
 
 209. THIS constellation, which compasses 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 mon- 
 ster, 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 between the 
 head of the Lesser and the tail of the Greater Bear. 
 
 210. Draco contains eighty stars, including two of the 2d 
 magnitude, three of the 3d, and sixteen of the 4th. 
 
 " The Dragon 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 situated as to form an irregu- 
 lar square ; the two upper ones being the brightest, and both 
 of the 2d magnitude. 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 
 U is most frequently called. The other bright star, about 4 from it on the left, is 
 Rastdben. 
 
 211. About 4 W. of Rastaben, 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 V, with the point toward the west, and the 
 open part toward the east. The small star in the nose, is called 
 Er Rakis. 
 
 209. Describe Draco its situation and extent. 210. Number and size of its princi- 
 pal stars? How may the head of Draco be distinguished? What said of Etanin? Ita 
 letter name? What of Rastaben? 211. Of Er Rakis? Further of Rastaben? 01 
 Etanin ? Of Grumium ? Of Omicron ? How may the second coil be recognized ? What 
 of Zcta ? Of Eta, Theta, and Asich ? Of Thuban, Kappa, and Giansar ? 
 
DRACO. J 1 ] 
 
 The two small stars 5* or 6 S. of Rastaben are in the left foot of Hercules* 
 
 Raataben 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 Poniato^skii, or the V. It is situated less than 2 west 
 o 'the solstitial colure, and is exactly in the zenith of London. Its favorable position has 
 lal English astronomers to watch its appearance, for loug periods, with the most exact and 
 unwearied scrutiny. 
 
 Of the four stars forming the irregular square in the head, the lower and right-hand one 
 is 5J$* N. of Etanin. It is called Q-rumiwn, and is of the 3d 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 is marked Omior&n, and lies 8 E. of Grumiura. This group is in the first 
 coil of the Dragon. 
 
 The second coil is about 13 below the first, and may be recognized 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 produced 10* further, will point out Zeta, a 
 star of the 3d magnitude, situated in the third coil. Zeta may otherwise be known, by its 
 being nearly in a line with, and midway between, Etanin and Kochab. From Zeta, the 
 remaining stars in this constellation are easily traced. 
 
 Eta, Theta, and Asich, come next ; all stars of the 3d magnitude, and at the distance 
 severally, of 6, 4, and 5" from Zeta. At Asich, the third star from Zeta, the tail of the 
 Dragon makes a sudden crook. Thuban, Kappa, and Giansar, follow next, and com- 
 plete the tail. 
 
 212. Teuton is a bright star of the 2d magnitude, 11 from 
 Asich, iu 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 Kappa, in the 
 tail of the Dragon, a large quadrilateral figure, whose longest side is from Megrez to 
 Kappa. 
 
 Giansar, the last star in the tail, is between the 3d and 4th magnitudes, and 5 from 
 Kappa. 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. 
 
 HISTORY. 
 
 Mythologists give various accounts of this constellation. By some it Is represented as 
 the watchful dragon which guarded the golden apples in the famous garden of the Hes- 
 perides, near Mount Atlas in Africa, and was siain by Hercules. Juno, who presented 
 these apples to Jupiter on the day of their nuptials, took Draco up to heaven, and made a 
 constellation of him, as a reward for his faithful services. Others maintain that in the war 
 with the giants, this dragon was brought into combat, and opposed to Mineiva, who seized 
 it in her hand, and hurled it, twisted as it was, into the heavens round the axis of the 
 world, before it had time to unwind its contortions, where it sleeps to this day. Other 
 writers of antiquity say, that this is the dragon killed by Cadmus, who was ordered by hia 
 father to go in quest of his sister Europa, whom Jupiter had carried away, and never tc 
 return to Phenicia without her. 
 
 " When now Agenor had his daughter lost, 
 
 He sent his son to search on every coast ; 
 
 And sternly bade him to his arms restore 
 
 The darling maid, or see his face no more." 
 
 214. Size and position of Thuban? What called by nautical men ? Hew otherwise 
 celebrated? What further of Kappa, M ; /ar. Megrez, Ac. ? 
 HISTORY. Various Mythological accounts? Story of Cadmus and the dragon's teeth V 
 
112 ASTRONOMY. 
 
 Hi -i search, however, proving fruitless, he consulted the oracle of Apollo, anl TTM 
 ordered to build a city where he should see a heifer stop in the grass, and to call tho 
 country Bceotia. He saw the heifer according to the oracle, and as he wished to render 
 thanks to the god by a sacrifice, he sent his companions to fetcli water from the neighbor- 
 ing grove. The waters were sacred to Mars, and guarded by a most terrific dragon, who 
 devoured all the messengers. Cadmus, tired of their seeming delay, went to the place, 
 and saw the monster still feeding on their flesh. 
 
 Cadmus, beholding such a scene, boldly resolved to avenge, or to share their fate. He 
 therefore attacked the monster with slings and ai'rows, and, with the assistance of 
 Minerva, slew him. He then plucked out his teeth, and sowed them, at the command of 
 Pallas, in a plain, when they suddenly sprung up into armed men. 
 
 Entertaining worse apprehension from the direful offspring than he had done from the 
 dragon himself, he was about to fly, when they fell upon each other, and were all slain in 
 one promiscuous carnage, except five, who assisted Cadmus to build the city of Bosotia. 
 
 TELESCOPIC OBJECTS. 
 
 1. a DRACONIS (Thubari) A star with a distant companion in the fifth coil of Draco ; R 
 A. 14h. 00m. 03s. ; Dec. N. 65* 08' 04". A S%, pale yellow; B 8, dusky ; two other stars In 
 the field. Upwards of 4,600 years ago, this was the pole-star of the Chaldeans. 
 
 2. 3 DBACONIS (Rastaberi) A star with a very distant companion, in the eye of Draco ; 
 R. A. 17h. 26m. 48s. ; Dec. N. 52* 25' 02'. A 2, yellow ; B 10, bluish ; other stars in field. 
 
 3. y DRACONIS (Etanin)A star with a telescopic companion, in the crown of Draco ; 
 R. A. 17h. 52m. 53s. ; Dec. N. 51 30' 06. A 2, orange tint ; B 12, pale lilac. A third star 
 in the field making a neat triangle with A and B. Etwnin is celebrated as the star by 
 viewing which, Bradly discovered the aberration of light in 1725. It is a zenith-star at 
 the Greenwich observatory. 
 
 4. 6 DRACONIS A bright star with a distant companion, in the second flexure ; R. A. 
 19h. 12m. 80s. ; Deo. N. 67' 22' 08'. A 3, deep yellow ; B 9%, pale red ; other small stars 
 in the field. 
 
 5. e DRACONIS A fine double star between the second and third flexures ; R. A. 19h. 
 48m. 41s. ; Dec. N. 69 51' 6". A 5}$, light yellow; B 8, blue; a third star just north 
 
 Of ft; 
 
 6. 7} DRACONIS A star with a companion, between the third and-fourth flexures ; R. A 
 I6h. 21m. 48s. ; Dec. N. 61* 52' 04". A 3, deep yellow ; B 11, pale grey. 
 
 7. jit DRACONIS A very neat BINARY SYSTEM, on the tip of the Dragon's tongue ; R. A 
 17h. 02m. 02s.; Dec. N. 54 41' 02". A 4, and B 4%, both white. Resembles Castor, 
 though'the components are nearer equal. Period, about 600 years. 
 
 8. A TRIPLE STAR in the first flexure; R. A. 18h. 21m. 36s.; Dec. N. 58 42' 05". A 5, 
 pale white; B 8%, light blue; C 7, ruddy. A difficult object about midway between 
 y and $. 
 
 9. A beautiful TRIPLE STAR in the nose of Draco, on a line from y over ft, and near 
 twice as much further ; R. A. 16h. 32m. 28s. ; Dec. N. 53" 14' 09". A 6, pale yellow ; B 6>$, 
 faint lilac ; C 6, white ; four other stars in view. 
 
 10. A BRIGHT-CLASS, OVAL NEBULA, under the body of Draco ; R. A. 15h. 02m. 03s. ; Dec. 
 N. 56 23' 0". Faint at the edges, with four stars in the field ; one quite near it. 
 
 11. A PLANETARY NEBULA, between the second and third coil, on a line from Polaris to y 
 Draconis: R. A. 17h. 58m. 38s.; Dec. 66 38' 01". A remarkably bright and pale blue 
 ob.iect, with several telescopic stars in the field. Map IX., Fig. 56. It is situated exactly 
 in Hie pole of Vie ecliptic. 
 
 LYRA (THE HARP). MAP Y. 
 
 213. This constellation is distinguished by one of the most 
 brilliant stars in the northern hemisphere. It is situated direct- 
 ly south of the first coil of Draco, between the Swan on the 
 
 TELESCOPIC OBJECTS. Alpha ? Beta? Gamma? Delta? -Epsilon? Eta? Mu? 
 Triple stars ? Nebulae? 
 
 218. TIow is Lyra distinguished? Where situated? Number and size of its prfno% 
 Jal stars ? 
 
LYRA. 113 
 
 cast, and Hercules on the west ; and when on the meridian, id 
 almost directly overhead. It contains twenty-one stars, includ- 
 ing 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 around, blazing imperial 
 In the first order." 
 
 214. This star " blazing imperial in the first order" is called 
 Vega, and sometimes Wega ; but more frequently, 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 Eltanin, and about 30 N. N. E. of 
 Ras Alhague and Has Algethi. It may be certainly known by 
 means of two small, yet conspicuous stars, of the 5th 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 ISpsilon, and the southern one 
 Zeta. About 2 S. E. of Zeta, and in a line with Lyra, is a star of the 4th magnitude, 
 marked Delta, in the middle of the Harp ; and 4 or 5 S. of Delta, are two stars of the 
 8d magnitude, about 2 apart, in the garland of the Harp, forming another triangle, whose 
 vertex is in Delta. The star on the east is marked Gamma ; that on the west, Beta. If 
 a line be drawn from Etanin through Lyra, and produced 6 farther, it will reach Beta. 
 
 This is a variable star, changing from the 3d to nearly the 5th magnitude in the space 
 of a week ; it is supposed to have spots on its surface, and to turn on its axis, like 
 our sun. 
 
 Gamma comes to the meridian 21 minutes after Lyra, and precisely at the same 
 moment with EpsUon, in the tail of the Eagle, 17}$ S. of it. 
 
 The remarkable brightness of a Lyra has attracted the admi- 
 ration of astronomers in all ages. Manillas, who wrote in the 
 age of Augustus, thus alludes to it : 
 
 *' ONE, placed in front above the rest, displays 
 A vigorous light and darts surprising rays." 
 
 Astronomicon, B. i. p. 15. 
 
 HISTORY. 
 
 It is generally asserted that this is the celestial Lyre which Apollo or Mercury gave to 
 Orpheus, and upon which he played with such a masterly hand, that even the most rapid 
 rivers ceased to flow, the wild beasts of the forest forgot their wilduess, and the moun- 
 tains came to listen to his song. 
 
 Of all the nymphs who used to listen to his song, Eurydyce was the only one who made 
 a deep impression on the musician, and their nuptials were celebrated. Their happiness, 
 however, was short. Aristaeus became enamored of Eurydice, and as she fled from her 
 pursuer, a serpent, lurking in the grass, bit her foot, and she died of the wound. Orpheus 
 resolved to recover her, or perish in the attempt. With his lyre in his hand, he entered 
 the infernal regions, and gained admission to Pluto, The king of hell was charmed with 
 his strains, the wheel of Ixion stopped, the stone of Sisyphus stood still, Tantalus forgot 
 his thirst, and even the furies relented. 
 
 Pluto and Proserpine were moved, and consented to restore him Eurydice, provided he 
 forbore Jooking behind till he had come to the extremest borders of their dark dominions. 
 
 214. Names of the most bnlliant star? How certainly known ? Where are KpdJen, 
 Zeta, Delta, Gamma, and Beta? What peculiarity about Bta ? In a Lyra:? 
 
 
. 
 
 114 ASTRONOMY. 
 
 The condition was accepted, and Orpheus was already in sight of the uppei egions of 
 Jie air, when he forgot, and turned back to look at his long-lost Eurydice. He saw her, 
 but she instantly vanished from his sight. He attempted again to follow her, but waa 
 refused admission. 
 
 From this time, Orpheus separated himself from the society of mankind, which so 
 offended the Thracian women, it is said, that they tore his body to pieces, and threw his 
 head into the Hebrus, still articulating the words Eurydice ! Eurydice! as it was carried 
 down the stream into the 2Egean sea. Orpheus was one of the Argonauts, of which cele- 
 brated expedition he wrote a poetical account, which is still extant. After his death, he 
 received divine honors, and his lyre became one of the constellations. 
 
 This fable, or allegory, designed merely to represent the power of music in the hands 
 of the great master of the science, is similarly described by three of the most renowned 
 Latin poets. Virgil, in the fourth book of hia Georgics, thus describes the effect of ti. 
 lyre : 
 
 " E'en to the dark dominions of the night 
 
 He took his way, through forests void of light, 
 
 And dared amid the trembling ghosts to sing, 
 
 And stood before the inexorable king. 
 
 The infernal troops like passing shadows glide, 
 
 And listening, crowd the sweet musician's side ; 
 
 Men, matrons, children, and the unmarried maid, 
 
 The mighty hero's more majestic shade, 
 
 And youth, on funeral piles before their parents laid. 
 
 E'en from the depths of hell the damn'd advance ; 
 
 The infernal mansions, nodding, seem to dance ; 
 
 The gaping three-mouth'd dog forgets to snari ; 
 
 The furies hearken, and their snakes uncurl ; 
 
 Ixion seems no more his pain to feel, 
 
 But leans attentive on his standing wheel. 
 
 All dangers past, at length the lovely bride 
 
 In safety goes, with her melodious guide." 
 
 Pythagoras and his followers represent Apollo playing upon a harp of seven strings, 
 by which is meant (as appears from Pliny, b. ii. c. 22, Macrobius i. c. 19, and Censorius 
 c. ii.), the sun in conjunction with the seven planets ; for -they made him the leader of 
 that septenary chorus, and the moderator of nature, and thought that by his attractive 
 furce he acted upon the planets in the harmonical ratio of their distances. 
 
 The doctrine of celestial harmony, bj which was meant the music of the spheres, was 
 common to all the nations of the East. To this divine music Euripides beautifully 
 alludes : " Thee I invoke, thou self-created Being, who gave birth to Nature, and whom 
 light and darkness, and the whole train of globes encircle with eternal music." So a.so 
 bhakspeare : 
 
 " Look, how the floor of heaven 
 
 Is thick inlaid, with patines of bright gold ; 
 
 There's not the smallest orb which thou behold'st, 
 
 But in his motion like an angel sings, 
 
 Still quiring to the young-eyed cherubim: 
 
 Such harmony is in immortal souls ; 
 
 But, while this muddy vesture of decay 
 
 Doth grossly close it in, we cannot hear it." 
 
 The lyre was a famous stringed instrument, much used among the ancients, said to 
 have been invented by Mercury about the year of the world 2,000 ; though some ascribe 
 the invention to Jubal. (Genesis iv. 21.) It is universally allowed, that the lyre was the 
 first instrument of the string kind ever used in Greece. The different lyres, at various 
 periods of time, had from four to eighteen strings each. The modern lyre is the Welsh 
 harp. The lyre, among painters, is an attribute of Apollo and the Muses. 
 
 All poetry, it has been conjectured, was in its origin lyric; that is, adapted to recita- 
 tion or song, with the accompaniment of music, and distinguished by the utmost boldness 
 of thought and expression ; being at first employed in celebrating the praises of gods 
 and heroes. 
 
 Lesbos was the principal seat of the Lyric Muse; and Terpander, a native of this 
 island, who flourished about 650 years B. C., is one of the earliest of the Lyric poets 
 whose name we find on record. Sappho, whose misfortunes have united with her taleuts 
 to render he< name memorable, was born at Mitylene, the chief city of Lesbos. She wan 
 
 HISTORY. Story of Orpheus and Eurydice ? Design of this myth ? Celebrated b/ wha> 
 poets ? Origin of the Lyre, and of Lyric poetry ? What said of Pindar ? 
 
TAURUS PONiATOWSKII. Uo 
 
 reckoned a tenth muse, and placed without controversy at the head of the female writers 
 in Greece. But Pindar, a native of Thebes, who flourished about 500 years B. C., is 
 styled the prince of lyric poets. To him his fellow-citizens erected a monument ; and 
 vhen the Lacedemonians ravaged Boeotia, and burnt the capital, the following words 
 were written upon the door of the poet: FOKBEAR TO BURN THIS HOUSE. IT WAS THH 
 
 DWELLING OF PlNDAR. 
 
 TELESCOPIC OBJECTS. 
 
 1. a LYR^E A star with a little companion ; R. A. 18h. 31m. 80s. ; Dec. N. 38 38' 01*. 
 A 1, pale sapphire ; B 11, smalt blue. Map VIII., Fig. 15. 
 
 a Lyria is computed to be 400,000 times as remote as our sun; or 38,000,000,000,000 
 distant ! And yet what is this to the mean distances of many of those of the 12th to 15tU 
 magnitudes ? 
 
 2. (3 LYR^E A star with its companions forming a quadruple system ; R. A. 18h. 44ra. 
 09s.; Dec. N. 33 10' 08'. A 3, very white and splendid; B 8, pale grey; 8^, faint 
 yellow ; D 9, light lilac, ft is regarded as variable. 
 
 8. y LYR.E A lustrous star 7 southeast of Vega, with a minute distant companion ' 
 R. A. 18h. 52m. 57s. ; Dec. N. 32 28' 05". A 3, bright yellow ; B 11, blue ; other tele- 
 Bcopic stars in the field. 
 
 4. e ~LYRJE A splendid MULTIPLE STAR, only 1% northeast of Vega; R. A. 18h. 89m. 
 02s. ; Dec. N. 39 30' 03". Map VIII., Fig. 16. With small instruments it appears simply 
 double ; but with better instruments each of the components are found to be double, and 
 binary systems. Between the twin systems are three minute stars. The components of 
 the two systems are described as A 5, yellow; B 6%, ruddy; C 5, and D 53, both white. 
 A, B are the lowest, or northern pair. 
 
 These two twin systems are in motion around a common center of gravity, as well as 
 the respective components around each other. The period of the individual systems is 
 estimated at about 2,i00 years; while 1,000,000 of years are supposed to be requisite for 
 a revolution round the common center of both ! 
 
 5. LYR^E A fine DOUBLE STAR about 2 south of e ; R. A. ISh. 39m. 15s. ; Dec. N. 37* 
 26' 05". A 5, topaz ; B 5%, greenish. 
 
 6. n LYRJE A neat DOUBLE STAR 6 east of Vega; R. A. 19h. 08m 18s. ; Dec. N. 38 52 
 05". A 5, sky blue ; B 9, violet tint. A fine object for a moderate telescope. 
 
 7. v LYR^E A QUADRUPLE STAR in the cross-piece of the Lyre ; R. A. ISh. 43m. 48s. ; Dec. 
 N. 32 38 0". A 9, pale yellow; B 13, bluish; C 11, pale blue ; D 15, blue; three other 
 Itars in the field. A very delicate object. 
 
 8. A GLOBULAR CLUSTER, in a splendid field, between the eastern yoke of Lyra and the 
 head of Cygnus ; R. A. 19h. 10m. 19s, ; Dec. N. 29 54' 02\ About 5% southeast of /3 Lyrae, 
 towards (3 Cygni, and 3%" from the latter. Map IX., Fig. 57. 
 
 9. An ANNULAR NEBULA between (3 and y ; R. A. ISh. 47m. 37s.; Dec. N. 82* 50' 01". 
 A wonderful object, in the form of an elliptical ring. Supposed by Herschel to be 900 
 times as distant as Sirius. A clear opening through its center, and several stars in tho 
 field. Map IX., Fig. 58. 
 
 TAURUS PONIATOWSKII. MAP V. 
 
 215. This small asterism is between the shoulder of Ophiu- 
 chus and the Eagle. The principal stars are in the head, and 
 of the 4th magnitude. They are arranged in the form of the 
 letter V, and from a fancied resemblance to the zodiac Bull, and 
 the Hyades^ became another Taurus. See description of Ser- 
 pentarius, article 206. 
 
 TELESCOPIC OBJECTS. Alpha ? Beta? Gamma? Epsilon? Point out on the map, 
 Zeta? Eta? Nu? What cluster? Point out on the. map. What nebula, and where 
 <)und on the map? 
 
 215. Describe Taurus Poniatowskii. Where situated ? 
 
1.16 ASTRONOMY. 
 
 TELESCOPIC OBJECTS. 
 
 1. A neat DOUBLE STAR in the space between the Polish Bull, and the Eagle's wing, tt 
 cast of a Ophiuchi, in a line towards Altair ; R. A. 17h. 58m. 17s. ; Dec. N. 11* 59' OS" 
 A 8, straw-color; B 8%, sapphire blue. 
 
 2. A fine PLANETARY NEBULA, in a rich vicinity, in the shoulder; R. A. 18h. 04m. 21s. , 
 Dec. N. 6* 49' 02*. A small but bright object, regarded by Prof. Strure as one of the motr 
 curious in the heavens. Many telescopic stars in the field. 
 
 SCUTUM SOBIESKI (SOBIESKI'S SHIELD). MAP Y. 
 
 216. This small figure is between the head of the Polish Bull, 
 and the head of Sagittarius. Its four principal stars are of the 
 5th magnitude ; and it is important chiefly for its Telescopic 
 Objects. 
 
 TELESCOPIC OBJECTS. 
 
 1. A DOUBLE STAR l%" northeast of fj. Sagittarii; R. A. ISh. 07m. 37s.; Dec. S. 19' 56' 
 05". A 8%, and B 10, both grey. 
 
 2. A nea* DOUBLE STAR, in a long and straggling assemblage below the Shield ; R. A. 
 18h. 10m. 36s. ; Dec. S. 17 11' 07". A 9, and B 11. both bluish. It is 4* from /z Sagittarii, 
 in a very rich vicinity ; several splendid fields lying only about 1" south of it. 
 
 8. A BEAUTIFUL CLUSTER below the base of the Shield ; R. A. 18h. 08m. 49s. ; Dec. S. 18* 
 27' 05". A line from a Aquilae, southwest over /I Antinoi, and continued as far again, 
 will reach this object. 
 
 4. A 'SCATTERED BUT LARGE CLUSTER, north-half-east from fj. Sagittarii 7" ; R. A. 18h. 
 09m. 44s. ; Dec. S. 13 50' 05". Stars disposed in pairs, the whole forming a very pretty 
 object in a telescope of tolerable capacity. 
 
 5. A HORSE-SHOE NEBULA just below the Shield ; R. A. 18h. llm. 23s. ; Dec. S. 16 15' 08". 
 It has been compared to a Greek G. Map IX., Fig. 59. Five stars in the object, and 
 others in the field, and the region around it particularly rich. Sir William Herschel 
 computed that there were 285,000 stars in a space 10 long, and 2}* wide; many of 
 which were 2,300 times as far off as Siriujs ! 
 
 SAGITTAEIUS (THE AECHEE). MAP V. 
 
 21 1. This is the ninth sign and the tenth constellation of the 
 Zodiac. It is situated next east of Scorpio, with a mean decli- 
 nation of 35 S., or 12 below the ecliptic. The sun enters this 
 sign on the 22d of November, but does not reach the constel- 
 lation before the 7th of December. It occupies a considerable 
 space in the southern hemisphere, and contains a number of sub- 
 ordinate, though very conspicuous stars. The whole number of 
 its visible stars is sixty-nine, including five of the 3d magnitude, 
 and ten of the 4th. 
 
 TELESCOPIC OBJECTS. What double star ? What nebula ? 
 
 21 tf. Situation and components of Scotum Sobieski? For what chiefly important 
 TELESCOPIC OBJECTS. What double stars ? Clusters? Nebula? 
 
 217. Order of Sagittarius, in the signs and constellations? When does the ouu into, 
 this sign f The conztcdation T Its extent? Number and size of its stars ? 
 
SAGITTARIUS. lU 
 
 218. Sagittarius may be readily distinguished by means of five 
 stars of the 3d and 4th magnitudes, forming a figure resem- 
 bling a little, short, straight-handled dfpper, turned nearly bot- 
 tom upward, 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 Au- 
 gust. Of the four stars forming the bowl of the Dipper, the two 
 upper ones are only 3 apart, and the lower ones 5. 
 
 The two smaller stars forming the handle, and extending westerly about 4J3*, 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 Lambda, 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 4M apart, extending toward the S. E. It is also equidistant 
 from Pki and Delta, with which it makes a handsome triangle, with the vertex in 
 Lambda. About 5 above Lambda, and a little to the west, are two stars close together 
 in the end of the bow, the brightest of which is of the 4th magnitude, and marked Mu. 
 This star serves to point out the winter solstice, being about ii N. of the tropic of Capri- 
 corn, and less than one degree east of the solstitial colure. 
 
 If a line be drawn from Sigma through Phi, and produced about 6" farther to the west, 
 it will point out Delta, and produced about 3 from Delta, it will point out Gfimma / 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 
 Ogures, may be easily traced from the map. 
 
 HISTORY. 
 
 This constellation, it is said, commemorates the famous Centaur Chiron, son of Philyra 
 and Saturn, who changed himself into a horse, to elude the jealous inquiries of his wife 
 Rhea. 
 
 Chiron was famous for his knowledge of music, medicine and shooting. He taught 
 mankind the use of plants and medicinal herbs; and instructed, in all the polite arts, 
 the greatest heroes of the age. He taught ./Esculapius physic, Apollo music, and Her 
 cules astronomy ; and was tutor to Achille*, Ason, and ^Eneas. According to Ovid, ho 
 was slain by Hercules, at the river Evenus, for offering indignity to his newly marrie 1 
 bride. 
 
 " Thou monster double shap'd, my right set free 
 Swift as his words, the fatal arrow flew; 
 The Centaur's back .admits the feather'd wood, v 
 And through his breast the barbed weapon stood; 
 Which, when in anguish, through the flesh he tore, 
 From both the wounds gush'd forth the spumy gore." 
 
 The arrow which Hercules thus sped at the Centaur, having been dipped in the blood 
 of the Lernaean Hydra, rendered the wound incurable, even by the father of medicine 
 himself, and he begf^f d Jupiter to deprive him of immortality, if thus he might escape 
 his excruciating paiu3. Jupiter granted his request, and translated him to a pla,cf 
 among the constellations. 
 
 " Midst golden stars he stands refulgent now, 
 
 And thrusts the Scorpion with his bended bow." 
 
 This is the Grecian account of Sagittarius ; but as this constellation appears on the 
 ancient zodiacs of Egypt, Dendera, Esne, and India, it seems conclusive that the Greeks 
 
 218. How distinguished? Where is Lambda? How known? Where are Mu, Delta, 
 and Gamma ? 
 
 HISTORV. What does* Sagittarius commemorate ? Story of Chiron ? What sii.il of the 
 antiquity of this constellation 
 
Ii8 ASTRONOMJf. 
 
 only borrowed the figure, while they invented tJie fable. This is knowc to be trre with 
 respect to very many of the ancient constellations. Hence the jargon of the conflicting 
 accounts which have descended to us. 
 
 TELESCOPIC OBJECTS. 
 
 1. fJ. SAGITTARII A MULTIPLE STAR in the north end of the Archer's bow ; R. A. 18h. 
 04m. 11s. ; Dec. S. 21 05' 07" About 25* east-northeast of An tares. A 3#, pale yellow; 
 B 16, blue ; C 9J<$, and D 10, both reddish. 
 
 2. a SAGITTARII A' star with a distant companion in the Archer's right shoulder; 
 R. A. ISh. 45m. 20s. ; Dec. S. 26 29' 03'. A 3, ruddy ; B 9 J$, ash-colored. 
 
 8. A very delicate TRIPLE STAR, between the heads of Sagittarius and Capricorn, about 
 25* south-by-west of Altair, and 10 west of ^ Capricorn! ; R. A. 19h. 31m. 33s.; Dec. S. 
 16 .39' 02". A 5%, yellow ; B 8, violet ; C 16, blue. Other small stars in the field. 
 
 4. A LARGE AND COARSE CLUSTER of minute stars, close to the upper end of the bow, and 
 In the Galaxy; R. A. ISh. 03m. 08s. ; Dec. S. 21 36' 01'. Stars of the 10th to 13th mag- 
 nitudes. A rich field of no particular form. 
 
 5. A LOOSE CLUSTER in the Galaxy, between the Archer's head and Sobieski's Shield ; 
 R. A. ISh. 22m. 14s. ; Dec. S. 19 10' 02'. The most prominent are a pair of 8th magni- 
 tude stars. It is about 5 northeast of jj, Sagittarii. 
 
 6. A FINE GLOBULAR CLUSTER between the head and bow, near the solsticial colure ; 
 R. A. ISh. 26m. 25s. ; Dec. S. 24 01' 04". A fine group, compressed towards the center, 
 with several single stars in the field. Map IX., Fig. 60. 
 
 CORONA AUSTRALIS (THE SOUTHERN CROWN). MAP V. 
 
 219. This is a small and unimportant constellation near the 
 fore-legs of Sagittarius ; and between them and the Milky-Way. 
 R. A. about 18h. 44m.; Dec. S. 40. Its four principal stars 
 are of the 5th magnitude, situated near each other, and arranged 
 in a gentle curve line, lying north and south. It has no Mytho- 
 logical History, or Telescopic Objects worthy of notice. 
 
 % t 
 
 AQUILA ET ANTINOUS (THE EAGLE AND ANTINOUS). MAP Y. 
 
 220. This double constellation is situated directly south of 
 the Fox and Goose, and between Taurus Poniatowskii on the 
 west, and the Dolphin on the east. It contains seventy-one 
 stars, including one of the 1st magnitude, nine of the 3d, arfd 
 seven of the 4th. It may be readily distinguished by the 
 position and superior brilliancy of its principal star. 
 
 221. Altair, the principal star in the Eagle, is of the 1st, or 
 between the 1st and 2d magnitudes. It is situated about 14 
 
 TELESCOPIC OBJECTS. Mu? Sigma? What triple star? What clusters? Whicl 
 shown on the map? Poiilt it out. 
 219. Describe Corona Australis. Its principal stars ? History and Telescopic Objects V 
 
 220. Situation of Aquila and Antinous? Number and size of its principal stars* 1 
 
 221. Altair how known? Stars each side of it? Use of Altair in navigation? Wha>. 
 
AQUILA ET ANTINOUS. 119 
 
 S. W. of the Dolphin. It may be known by its being the 
 largest and middle one of the three bright stars which are 
 arranged in a line bearing N. W. and S. E. The stars on each 
 side of Altair are of the 3d magnitude, and distant from it about 
 2. This row of stars very much resembles that in the Guards 
 of the Lesser Bear. 
 
 Altair is one of the stars from which the moon's distance is 
 taken for computing longitude at sea. Its mean declination is 
 nearly 8 N., and when on the meridian, it occupies nearly the 
 same place in the heavens that the sun does at noon on the 12th 
 day of April. It culminates about 6 minutes before 9 o'clock, 
 on the last day of August. It rises acronically about the begin- 
 ning of June. 
 
 Ovid alludes to the rising of this constellation ; or, more probably, to that of the prin- 
 cipal star, Altair : 
 
 " Now view the skies, 
 
 And you'll behold Jove's hook'd-bill bird arise." 
 
 Maasey's Fasti. 
 
 " Among thy splendid group 
 
 ONE dubious whether of the SECOND RANK, 
 Or to the FIRST entitled ; but whose claim 
 Seems to deserve the FIRST." 
 
 Eudosia. 
 
 The northernmost star in the line, next above Altair, is called Tarazed. In the wing 
 of the Eagle, there is another row composed of three stars, situated 4 or 5 apart, 
 extending down toward the southwest ; the middle one in this line is the smallest, being 
 only of the fourth magnitude; the next is of the 8d magnitude, marked Delta, and 
 situated 8" S. W. of Altair. 
 
 As you proceed from Delta, there is another line of three stars of the 3d magnitude, 
 between 5 and 6" apart, extending southerly, but curving a little to the west, which 
 mark.the youth Antinous. The northern wing of the Eagle is not distinguished by any 
 conspicuous stars. 
 
 Zeta and Epsilon, of the Sd magnitude, situated in the tail of the Eagle, are about 2" 
 apart, and 12' N. W. of Altair. The last one in the tail, marked Epsilon, is on the same 
 meridian, and culminates the same moment with Gamma, in the Harp. 
 
 From Epsilon, in the tail of the Eagle, to Theta, in the wrist of Antinous, may be tracel 
 a long line of stars, chiefly of the 3d magnitude, whose letter names are Theta, Eta, Mu, 
 Zeta and Epsilon. The direction of this line is from S. E. to N. W., and its length is 
 about 25. 
 
 Eta is remarkable for its changeable appearance. Its greatest brightness continues 
 but 40 hours; it then gradually diminishes for 66 hours, when its luster remains station- 
 ary for 80 hours. It then waxes brighter and brighter, until it appears again as a star 
 of the 3d magnitude. . 
 
 From these phenomena, it is inferred that it not only has spots on its surface, like our 
 sun, but that it also turns on its axis. 
 
 Similar phenomena are observable in Algol, Beta, in the Hare, Delta, in Cepaeus, and 
 Omicron, in the Whale, and many others. 
 
 "Aquila the next, 
 
 Divides the ether with her ardent wing: 
 Beneath the Swan nor far from Peffasufl, 
 POETIC EAGLB." 
 
 pretic quotation? Where are Tarazed and Delta? Zeta and Epsilon? Theta? Kbi 
 For what remarkable ? 
 
120 ASTRONOMY. 
 
 HISTORY. 
 
 Aquila, or the Eagle, is a constellation usually joined with Antinous. Aquila in aur. 
 posed to have been Merops, a king of the island of Cos, in the Archipelago, and the hus- 
 band of Clymene, the mother of Phaeton ; this monarch having been transformed into an 
 eagle, and placed among the constellations. Some have imagined that Aquila was the 
 eagle whose form Jupiter assumed when he carried away Ganymede ; others, that it 
 represents the eagle which brought nectar to Jupiter while he lay concealed in the cave a*. 
 Crete, to avoid the fury of his lather, Saturn. Some of the ancient poets say, that this 
 is the eagle which furnished Jupiter with weapons in his war with the giants : 
 " The towering Eagle next doth boldly soar, 
 As if the thunder in his claws he bore ; 
 He's worthy Jove, since he, a bird, supplies 
 The heaven with sacred bolts, and arms the skies." 
 
 McmUius 
 
 The eagle is justly styled the "sovereign of birds," since he is the largest, strongest, 
 and swiftest of all the feathered tribe that live by prey. Homer calU the eagle, " thts 
 strong sovereign of the plumy race ;" Horace styles him 
 
 " The royal bird, to whom the king of heaven 
 The empire of the feathered race has given :" 
 
 And Milton denominates the eagle the " Bird of Jove." Its sight Is quick, strong and 
 piercing, to a proverb : Job xxix., 28, &c. 
 
 " Though strong the hawk, though practised well to fly, 
 An eagle drops her in the lower sky ; 
 An eagle when deserting human sight. 
 She seeks the sun in her unwearied flight; 
 Did thy command her yellow pinion lift 
 So high in air, and set her on the clift 
 Where far above thy world she dwells alone, 
 And proudly makes the strength of rocks her own; 
 Thence wide o'er nature takes her dread survey, 
 And with a glance predestinates her prey? 
 She feasts her young with blood ; and hovering o'er 
 The uuslaughtered host, enjoys the promise^ gore." 
 
 ANTINOUS. 
 
 A: tinous is a part of the constellation Aquili, and wJ invented by Tycho Brane 
 Antinous was a youth of Bithynia, in Asia Minor. So greatly was his death lamented 
 by the emperor Adrian, that he erected a temple to his memory, and built in honor of 
 him a splendid city, on the banks of the Nile, the ruins of which are still visited by 
 travelers with much interest. 
 
 TELESCOPIC OBJECTS. 
 
 1. a AQUIL.B (Altair) A bright star in the neck, with a distant companion ; R. A. 
 19h. 42m. 58s. ; Dec. N. 8 26' 09*. A 1%, pale yellow; B 10, violet tint. 
 
 2. 13 AQUILA (Alshairi) A DOUBLE STAR, also in the neck of Aquila, and the head of 
 Antinous; R. A. 19h. 47m. 26s.; Dec. N. 6 00' 07". About 2^ south-southeast of 
 Altair. A 3%, pale orange ; B 10, pale grey ; with other stars in the field. 
 
 3. y AQUILA (Tarazed)-A. star in the back of Aquila, on a line with a and /?, with .1 
 minute companion ; R. A. 19h. 38m. 38s. ; Dec. N. 10 13' 06". A 3, pale orange ; B 12, 
 dusky ; other stars around. 
 
 4. 6 AQUILA, in the southern wing ; R. A. 19h. 17m. 25s. ; Dec. N. 2' 48' 00'. Has a 
 distant companion. A 3 J$, white ; B 12, livid ; other stars in the field. 
 
 5. AQUILA, in the tail ; R. A. 18h. 58m. 02s. ; Dec. N. 13" 37' 08". A 8, greenish tint; 
 B 11, livid ; two other stars in the field. 
 
 6. A neat DOUBLE STAR on the margin of the lower wing ; R. A. ISh. 57m. 59s. ; Dec. N. 
 6* 18' 08'. A 7)6, lucid white ; B 9, cerulean blue. A fine object, not difficult to find, aa 
 
 HLSTORT. Different suppositions respecting? Manilius? Horace? Miltcn? What 
 s;iid of Antinous? 
 
 TELESCOPIC OBJECTS. Alpha? Beta? Gamma? Delta? Xi? Other double 
 \Vhatclustcrs? Which shown on the map? What utbul;i? 
 
SAGITTA ANSER ET VULPECULA. 121 
 
 It lies 10* due noith of A Antinoi, a 3d magnitude star, and 13* west of /? Aquilae. The 
 brul cest object of its immediate neighborhood. 
 
 7. A WIDE DOUBLE STAR about 4 west-by-south of A Antinoi, between the foot and 
 Sobieski's Shield ; R. A. ISh. 41m. 07s. ; Dec. S. 6 05' 03". A 7, orange tint; B 9, ceru- 
 lean blue. Many telescopic stars in the field. 
 
 8. A SPLENDID CLUSTER close to the southeast of the last described object; R. A. ISh, 
 12m. 32s. ; Dec. S. 6' 27' 02'. It is between the left foot and Sobieski's Shield. A gor- 
 geous object " somewhat resembling a flight of wild ducks in shape," has an 8th magni- 
 tude star in the middle, and two larger east of it ; probably all three between us and 
 the cluster. Map IX., Fig. 61. 
 
 9. A LOOSE CLUSTER between the lower wing and the leg of Antinous, and 13 southwest 
 3f Altair, on a line from Vega through e Aquilae ; R. A. 19h. 08m. 36s. ; Dec. S. 1 11' 09" 
 A splashy group of stars from the 9th to the 12th magnitudes, on the easteAi margin of 
 the Galaxy. 
 
 10. A STELLAR NEBULA on the Eagle's back, about 5* west of Altair; R. A. 19h. 23m. 
 D5s. ; Dec. N. 8* 54' 01". A minute object in the Milky- Way ; and in the most powerful 
 telescopes, fan-shaped. 
 
 SAGITTA (THE AEEOW.) MAP Y. 
 
 222. SAGITTA is a small but old constellation between the 
 Fox and Goose on the north, and the Eagle on the south. Its 
 two principal stars are of the 4th magnitude, and lie nearly east 
 and west, about 4 apart. The next two largest stars are of the 
 5th magnitude. 
 
 TELESCOPIC OBJECTS. 
 
 1. SAGITTA A star with a distant companion about 8* north-northwest of Altair, on 
 a line towards Vega; R. A. 19h. 30m. 03s. ; Dec. N. 16" 06' 5". A 6, pale white ; B 8, 
 light blue. 
 
 2. SAGITT^B A neat DOUBLE STAR just above the Arrow, 9" south by east from ft 
 Cygni, and 10 north of Altair; R. A. 19h. 41m. 53s.; Dec. N. 18 44' 8". A 5, silvery 
 white ; B 9, blue. 
 
 3. &. SAGITT-B A TRIPLE STAR near the head of the Arrow, about half-way from ft 
 Cygni to a Delphini ; R. A. 20h. 02m. 53s. ; Dec. N. 20 26' 6'. A 7, pale topaz ; B 9, grey * 
 C 8, pearly yellow. 
 
 4. A RICH COMPRESSED CLUSTER on the shaft of the arrow, 10 northeast of Altair 
 R. A. 19h. 46m. 36s. ; Dec. N. 18 22' 1". Telescopic stars around it. 
 
 AKSER ET VULPECULA (THE FOX AND GOOSE). MAP V. 
 
 223. This is a modern constellation, situated between the 
 Swan on the north, and the Arrow or the Dolphin and Eagle on 
 the south. It is composed of some thirty stars, the largest of 
 which is of the 3d magnitude. 
 
 TELESCOPIC OBJECTS. 
 
 1. A star V7ith a distant companion on the nose of Reynard, and neck of the Qooao 
 B^ south of ft Cygni ; R. A. 19h. 22m. 08s. ; Dec. N. 24" 20' J'. 
 
 922. Describe Sagitta its principal stars. 
 
 TKLRSCOPIC OBJECTS. Epsilon? Zeta? What triple star? Cluster V 
 
 228. Describe the Fox and Gx>o^. Its component stars? 
 
ASTRONOMY. 
 
 2. A WIDE DOUBLE STAR, 11 J$* north of Altair, between the Fox and the Arrow, in tho 
 eastern edge of the Galaxy; R. A. 19h. 46m. 20s.; Dec. N. 19 65' 5". A and B both 7 
 tnd both white. 
 
 3. A LARGE STRAGGLING CLUSTER on the neck of the Goose, and about 3 from (3 Cygni; R. A 
 19h. 20m. 30s. ; Dec. N. 24 49' 3'. Two 7th magnitude stars in the west. The cluster 
 has the form of a Greek Q. t ' 
 
 4. The celebrated DUMB-BKLL NEBULA, on the Fox's breast, about 7* southeast of Cygni, 
 and nearly half-way between it and the Dolphin ; R. A. 19h. 52m. 39s. ; Dec. N. 22* 17' 1". 
 (Map IX., Fig. 62.) This magnificent and singular object is in a crowded vicinity, where 
 Cold after field is very rich. 
 
 CHAPTER XI. 
 
 CONSTELLATIONS ON THE MERIDIAN IN SEPTEMBER. 
 
 DELPHINUS (THE DOLPHIN). MAP V. 
 
 224. THIS beautiful little cluster of stars is situated 13 or 
 1 4 N. E. of the Eagle. It consists of eighteen stars, including 
 four of the 3d magnitude, but none larger. It is easily distin- 
 guished from all others, by means of the four principal stars in 
 the head, which are so arranged as to form the figure of a dia- 
 mond, pointing N. E. and S. W. To many, this cluster is 
 known by the name of Job's Coffin ; but from whom, or from 
 what fancy, it first obtained this appellation, is not known. 
 
 225. There is another star of the 3d magnitude, situated in 
 the body of the Dolphin, about 3 S. W. of the Diamond, and 
 marked Epsilon. The other four are marked Alpha, Beta, 
 Gamma, Delta. Between these are several smaller stars, too 
 small to be seen in presence of the moon. 
 
 The mean decimation of the Dolphin is about 15 Ts T . 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. What double stars ? Cluster? Nebula ? Point out on the map. 
 
 224. Constellations in this chapter? Delphinus? Number and size of stars? How 
 aistiaguished? What other name has this constellation? 225. Where are Epsilou, 
 Alpha, Beta, Gamma and Delta? Mean declination, Ac. 
 
HISTORY. 
 
 The DolpLm, according to some mythologists, was made a constellation by Neptunfa 
 Decause one of these beautiful fishes had persuaded the goddess Ampliitrite, who had made 
 a vow of perpetual celibacy, to become the wife of that deity ; but others maintain, that 
 it is the dolphin which preserved the famous lyric poet and musician Arion, who was a 
 Dative of Lesbos, an island in the Archipelago. 
 
 He went to Italy with Periander, tyrant of Corinth, where he obtained immense riches 
 by his profession. Wishing to revisit his native country, the sailors of the ship in whi;h 
 he embarked resolved to murder him, and get possession of his wealth. Seeing them 
 immovable in their resolution, Arion begged permission to play a tune upon his lute 
 before he should be put to death. The melody of the instrument attracted a number of 
 dolphins around the ship ; he immediately precipitated himself into the sea ; when one 
 of them, it is asserted, carried him safe on his back to Taenarus, a promontory of Laco- 
 nia, in Peloponnesus ; when he hastened to the court of Periander, who ordered all the 
 Bailors to be crucified at their return. 
 
 " But (past belief), a dolphin's arched back 
 Preserved Arion from his destined wrack ; 
 Secure he sits, and with harmonious strains 
 Requites his bearer for his friendly pains." 
 
 When the famous poet Hesiod was murdered in Naupactum, a city of JEtolia, in Greeae, 
 and his body thrown into the sea, some dolphins, it is said, brought back the floating 
 corpse to the shore, which was immediately recognized by his friends ; and the assassins 
 being afterwards discovered by the dogs of the departed bard, were put to death by 
 immersion in the same sea. 
 
 Taras, said by some to have been the founder of Tarentum, now Tarento, in the south 
 of Italy, was saved from shipwreck by a dolphin ; and the inhabitants of that city pre- 
 served the memory of this extraordinary event on their coin. 
 
 The natural shape of the dolphin, however, is not incurvated, so that one might ride 
 upon its back, as the poets imagined, but almost straight. When it is first taken from 
 the water, it exhibits a variety of exquisitely beautiful but evanescent tints of color, that 
 pass in succession over its body until it dies. They are an extremely swift-swimming 
 fish, and are capable of living a long time out of water ; in fact, they seem to delight to 
 gambol, and leap out of their native element. 
 
 " Upon the swelling waves the dolphins show 
 Their bending backs; then swiftly darting go, 
 And in a thousand wreaths their bodies show." 
 
 TELESCOPIC OBJECTS. 
 
 1. a, DELPHINI A bright star with a distant telescopic companion; R. A. 20h. 82m. 
 12s. ; Dec. N. 15* 21' 01'. A 8%, pale white ; B 13, blue. 
 
 2. (3 DELPHINI A delicate TRIPLE STAR on the Dolphin's body, 1J$ south-by-west of a, 
 in a line with {3 Cygni and y Lyra; R. A. 20h. 30m. 03s.; Dec. N. 14' 02' 06". A 4, 
 greenish tinge ; B 15, and C 12, both disky. 
 
 8. y DELPHINI A beautiful DOUBLE STAR in the head, 2 east of a ; R. A. 20h. 89m. 
 15s.: Dec. N. 15 83' 02'. A 4, yellow; B 7, light emerald, with a third star about 2' 
 distant. 
 
 4. A delicate QUADRUPLE STAR, near e in the tail ; R. A. 20h. 23m. 85s. ; Dec. N. 10" 48' 
 06*. A 7M, and B 8, both white; C 16, blue ; D 9, yellowish ; several other small stars 
 in the field. Map VIII., Fig. 17. 
 
 5. A SMALL BRIGHT CLUSTER, in the Dolphin's tail, S% south of e ; R. A. 20h. 26m. 21s. ; 
 Dec. N. 6 53' 02". Just east of a 9th magnitude star a coarse telescopic pair at a 
 distance, and several minute stars in the field. 
 
 6. A small PLANETARY NEBULA, betwen the pectoral fin and the arrow head, 6* north- 
 northwest of a, and exactly on a line towards Vega Lyrae ; R. A. 20b. 15m. 15s. ; Dec. N 
 19 35, 06". It is in a coarse cluster, in the center of which are fou 4 c^rpi<y>w tara. 
 
 HISTORY. Accounts of the origin of Delphinus? What said of Hesiod? Of Taras? 
 Of the natural shape, &c. ? 
 
 TKLESCOPIC OBJECTS. Alpha ? Beta? Gamma? What quadruple star? Point out 
 m the map. What cluster? Nebula? 
 
124 ASTRONOMY. 
 
 OYGNUS (THE SWAN). MAP Y. 
 
 226. This remarkable constellation is situated in the Milky- 
 Way, directly E. of Lyra, and nearly on the same meridian with 
 the Dolphin. It is represented on outspread wings, flying down 
 the Milky-Way, toward the southwest. 
 
 The principal stars which mark the wings, the body and the 
 bill of Cygnus, are so arranged as to form a large and regular 
 Cross ; the upright piece lying along the Milky- Way from N. E. 
 to S. W., while the cross piece, representing the wings, crosses 
 the other at right angles, from S. E. to N. W. 
 
 227. Arided or Dene.b Cygni, in the body of the Swan, is a 
 itar of the second magnitude, 24 E. N. E. of Lyra, and 30 
 directly N. of the Dolphin. It is the most brilliant star in the 
 constellation. It is situated at the upper end of the cross, and 
 comes to the meridian at 9 o'clock on the 16th of September. 
 
 Sad'r is a star of the 8d magnitude, 6* S. W. of Deneb, situated exactly in the cross, 
 or where the upright piece intersects the cross piece, and is about 20 E. of Lyra. 
 
 Delta, the principal star in the west wing, or arm of the cross, is situated N. W. of 
 Sad'r, at the distance of little more than 8, and is of the 3d magnitude. Beyond Delta, 
 toward the extremity of the wing, are two smaller stars about 5" apart, and inclining a 
 little obliquely to the north ; the last of which reaches nearly to the first coil of Draco. 
 These stars mark the west wing ; the east wing may be traced by means of stars very 
 similarly situated. 
 
 6-ienah is a star of the 3d magnitude, in the east wing, just as far east of Sad'r in the 
 center of the cross, as Delta is west of it. This row of three equal stars, Delta, Sad'r 
 and Gienah, form the bar of the cross, and are equi-distant from each other, being about 
 8 apart. Beyond Gienah on the east, at the distance of 6 or 7, there are two other 
 stars of the 3d magnitude; the last of which marks the extremity of the eastern wing. 
 
 The stars in the neck are all too small to be noticed. There is one, however, in the 
 beak of the Swan, at the foot of the cross, called Albireo, which is of the 3d magnitude, 
 and can be seen very plainly. It is about 16 S. W. of Sad'r, and about the same dis- 
 tance S. E. of Lyra, with which it makes nearly a right angle. 
 
 " In the small space between Sad'r and Albireo," says Dr. Herschel, " the stars in the 
 Milky-Way seem to be clustering into two separate divisions ; each division containing 
 more than one hundred and sixty-Jive thousand stars." 
 
 Albireo bears northerly from Altair, about 20*. Immediately south and southeast of 
 Albireo, may be seen the Fox and GOOSE ; and about midway between Albireo and Altair, 
 there may be traced a line of four or five minute stars, called the ARROW ; the head of 
 which is on the S. W., and can be distinguished by means of two stars situated close 
 together. 
 
 228. According to the British catalogue, this constellation 
 contains eighty-one stars, including one of the 1st or 2d magni- 
 tude, six of the 3d, and twelve of the 4th. The author of the 
 following beautiful lines says there are one hundred and seven. 
 
 "Thee, silver Swan, who 1 , silent, can o'erpass? 
 A hundred with seven radiant stars compose 
 Thy graceful form : amid the lucid stream 
 
 226. Situation of Cygnus? How represented? Figure made by its principal stars? 
 Its position? 227. Which is the brightest of its stars? Describe Sad'r, Delta, Gienah, 
 Albireo. Remark of Dr. Herschel? 228. Number of stars in Cygnus? Variable 
 stars ? What are they supposed to indicate ? 
 
CYGNUS. 125 
 
 Of the fair Milky- Way distinguished : one 
 
 Adorns the second order, where she cuts 
 
 The waves that follow in her utmost track; 
 
 This never hides its fire throughout the night, 
 
 And of the rest, the more conspicuous mark 
 
 Her snowy pinions and refulgent neck." JSudosia, b. ir. 
 
 Astronomers have discovered three variable stars in the Swan. CM, situated in the 
 neck, between Beta and Sad'r, was first observed to vary its brightness in 1686. Its peri- 
 odical changes of light are now ascertained to be completed in 405 days. Sad'r is also 
 changeable. Its greatest luster is somewhat less than that of a stur of the 3d magnitude, 
 and it gradually diminishes till it reaches that of the 6th. Its changes are far from being 
 regular, and, from present observations, they do not seem to recur till after a period of 
 ten years or more. 
 
 A third variable star was discovered in the head on the 20th of June, 1670, by Anthelme. 
 It appeared then to be of the 3d magnitude, but was so far diminished in the following 
 October, as to be scarcely visible. In the beginning of April, 1671, it was again seen, and 
 was rather brighter than at first. After several changes, it disappeared in March, 1672- 
 and has not been observed since. 
 
 These icmarkable facts seem to indicate, that there is a brilliant planetary system in 
 this constellation, which, in some of its revolutions, becomes visible to us. 
 
 HISTORY. 
 
 Mythologists give various accounts of the origin of this constellation. Some suppose 
 it is Orpheus, the celebrated musician, who, on being murdered by the cruel priestess of 
 Bacchus, was changed into a Swan, and placed near his Harp in the heavens. Otherg 
 suppose it is the swan into which Jupiter transformed himself when he deceived Leda, 
 wife of Tyndarus, king of Sparta. Some affirm that it was Cycnus, a son of Neptune, 
 who was so completely invulnerable that neither the javelins nor arrows, nor even tho 
 blows of Achilles, in furious combat, could make any impression. 
 
 " Headlong he leaps from off his lofty car, 
 And in close fight on foot renews the war ; 
 But on his flesh nor wound nor blood is seen, 
 The sword itself is blunted on the skin." 
 
 But when Achilles saw that his darts and blows had no effect on him, he Immediately 
 threw him on the ground and smothered him. While he was attempting to despoil him 
 of his armor, he was suddenly changed into a swan. 
 
 44 With eager haste he went to strip the dead ; 
 The vanished body from his arms was fled. 
 His sea-god sire, to immortalize his fame, 
 Had turned it to a bird that bears his name." 
 
 According to Ovid, this constellation took its name from Cycnus, a relative of Phaeton, 
 who deeply lamented the untimely fate of that youth, and the melancholy end of hia 
 sinters, who, standing around his tomb, wept themselves into poplars. 
 
 " Cycnus beheld the nymphs transformed, allied 
 To their dead brother on the mortal side, 
 In friendship and affection nearer bound ; 
 He left the cities, and the realms he owned, 
 Through pathless fields, and lonely shores to range ; 
 And woods made thicker by the sisters' change : 
 While here, within the dismal gloom alone, 
 The melancholy monarch made his moan ; 
 His voice was lessened as he tried to speak, 
 And issued through a long-extended neck: 
 His hair transforms to down, his fingers meet 
 In skinny films, and shape his oary feet ; 
 From both his sides the wings and feathers break : 
 And from his mouth proceeds a blunted beak ; 
 All Cycnus now into a swan was turned." Ovid's Met. h. H. 
 
 HISTOKT. Various accounts ? Story of Cycnus and Achilles ? Ovid's account t Vlr- 
 gilS runarkj respecting the Swan? 
 
126 ASTRONOMY. 
 
 Virgil, also, the 10th book of his ^Eneid, alludes to the same fable : 
 u For Cycnus loved unhappy Phaeton, 
 And sung his loss in poplar groves alone 
 Beneath the sister shades to soothe his grief; 
 Heaven heard his song, and hasten'd his relief 
 And changed to snowy plumes his hoary hair, 
 And wing'd his flight to sing aloft in air." 
 
 Of all the feathered race, there is no bird, perhaps, which makes so beautiful and 
 majestic an appearance as the.swan. Almost every poet of eminence has taken notico 
 of it. The swan has, probably, in all ages, and in every country where taste and ele- 
 gance have been cultivated, bean considered as the emblem of poetical dignity, purity, 
 and ease. By the ancients it was consecrated to Apollo and the Muses ; they also enter- 
 tained a notion that this bird foretold its own end, and sang more sweetly at the 
 approach of death. 
 
 She, like the swan 
 
 Expiring, dies in melody." 
 " So on the silver stream, when death is nigh, 
 The mournful swan sings its own elegy." Ovid's Tristia. 
 
 TELESCOPIC OBJECTS. 
 
 1. a CYGNI (Deneb) A bright star on the back of the Swan, with a telescopic com- 
 panion ; R. A. 20h. 35m. 57s. ; Dec. N. 44 42' 07". A 1, brilliant white ; B 12}$, pale blue. 
 
 2. {3 CYGNI (Albireo)*. bright DOUBLE STAB on the bill of the figure ; R. A. 19h. 24m. 
 16s. ; Dec. N. 27 37' 07". About 13 V south-southeast of Vega. A 3, topaz yellow ; B 7, 
 sapphire blue ; the colors in brilliant contrast. A fine object, and the first double star 
 ever seen by the present editor. 
 
 3. 6 CYGNI A most delicate DOUBLB STAR in the middle of the left wing, 14* west of a 
 Cygni; R. A. 19h. 39m. 58s.; Dec. N. 44" 44' 06". A 3J$, pale yellow; B 9, sea green. 
 Another beautiful object. 
 
 4 C CYGNI A star with a distant companion, on the tip of the right wing ; R. A. 21h. 
 06m. 07s.; Dec. N. 29 84' 05". A 3, pale yellow; B 10, sky blue; the field rich in 
 small stars. 
 
 5. "k CYGNI A close DOUBLE STAR in the right or lower wing, with a distant companion ; 
 R. A. 20h. 41m. 11s. ; Dec. N. 85* 54' 03". A 5, B 10, and C 6, all bluish. 
 
 6. V CYGNI A beautiful DOUBLE STAR, with a distant companion, on the very tip of the 
 right wing; R. A. 21h. 86m. 59s.; Dec. N. 28 01' 04". A 5, white; B 6, and TJ6, 
 both blue. 
 
 7. A BINARY STAR (61 Cygni) the most remarkable known in the heavens. It is situ- 
 ated on the inner tip of the right wing of Cygni, 7% south-by-east of Deneb, and nearly 
 east of Vega ; R. A. 20h. 59m. 43s. ; Dec. N. 37 58' 0". A 52$, and B 6, both yellow, but 
 the latter of the deepest tint. From the great rapidity of its proper motion, this star 13 
 regarded as one of the nearest to our system. It affords a positive instance of a double 
 star which, besides the individuals revoiving round each other, or about their common 
 center of gravity, has a progressive uniform motion towards some determinate region. It ia 
 supposed to be not less than 412,000 times the diameter of the earth's orbit from us ; or 
 88,190,000,000,000 miles distant ;, and to be moving through space 60,000 times as fast as 
 Mercury the swiftest body known to our system. The period of 61 Cygni as a binary 
 system, is about 450 years. For orbit, &c., see Map VIII., Fig. 18, and 19. 
 
 8. A fine DOUBLB STAR on the tip of the left wing, 10 northwest of a Cygni, and within 
 1* of 0; R. A. I9h. 87m. 84s. ; Dec. N. 50 09' 8". A 6% and B 7, both pale fawn color. 
 
 9. A WIDE QUADRUPLE STAR in a rich field, on the Swan's left thigh, about 8* west by 
 north of Deneb ; R. A. 20h. 08m. 86s. ; Dec. N. 46* 15' 6'. A 4, orange ; B 16, livid ; C 7%, 
 and D 53$, both cerulean blue. Not the effect of contrast. 
 
 10. A NEAT SMALL CLUSTER in the root of the neck, about 2 south of y; R. A. 20h. 18m. 
 17s. ; Dec. N. 37 59' 9". A 8, yellow; B 11, dusky. 
 
 11. A LOOSE SPLASHY CLUSTER in a rich vicinity, between the Swan's tail and the Lizard, 
 due south of (3 Cephei, and east-northeast of Deneb ; R. A. 21h. 26m. 29s. ; Dec. N. 47' 
 48' 8". 
 
 TELESCOPIC OBJECTS. Alpha? Beta? Delta? Zeta? Lambda? Mu? What cele- 
 brated binary star? Remarks respecting? Period? Point out on the map. What 
 other double star ? Quadruple? What clusters ? Nebula? 
 
CAPRICORNUS. 127 
 
 12. A riRT SIWGUIAR NEBULA on the tip of the northern wing, about 5j* north of 
 <? ; R. A. 19h. 40m. 35s. ; Dec. N. 50" 07' 6*. Seen to be nebulous only with good instru- 
 ments. Several telescopic stars in the field. The Herschels considered this aa a con 
 necting link between planetary nebula and nebulous stars. 
 
 CAPEICORNUS (THE GOA T ).-MAP V. 
 
 229. 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 tbe 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 December, but does not 
 reach the constellation Capricorn until the 16th of January. 
 
 The sun, having now attained its utmost declination 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 southern hemisphere enjoys the same light and he?t 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. 
 
 230. 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. 
 
 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 and Dalih. They are 28 from the Dolphin, in a 
 southerly direction. 
 
 Giedi is the most northern star of the two, and is double. Tf a line be drawn from 
 Lyra through Altair, and produced about 23 farther, it will point out the head of Capri- 
 corn. 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. 
 
 HISTORY. 
 
 Capricornus is said to be Pan, or Bacchus, who, with some other deities, were feasting 
 near the banks of the Nile, when suddenly the dreadful giant Tyjihon came upon them, 
 and compelled them all to assume a different shape, in order to escape his fury. Ovid 
 relates, 
 
 " How Typhon, from the conquer'd skies, pursued 
 Their routed godheads to the seven-mouth'd flood : 
 
 229. Position of Capricornus? When does the sun enter it? What said of his place 
 and motion at that time? Of the winter solstice? 230. Number of stars in Capri- 
 corn? Their magnitudes? How recognize the figure ? What said of Giedi? Ancient 
 name of this sign ? 
 
128 ASTRONOMY. 
 
 Forced every god (his fury to escape), 
 
 Some beastly form to take, or earthly shape. 
 
 Jove (sings the bard) was changed into a ram, 
 
 From whence the horns of Libyan Amnon came; 
 
 Bacchus a goat ; Apollo was a crow ; 
 
 Phoebe a cat ; the wife of Jove a cow, 
 
 Whose hue was whiter than the falling snow; 
 
 Mercury to a nasty ibis turned 
 
 While Venus from a fish protection craves, 
 
 And once more plunges in her native waves." 
 
 On this occasion it is further related that Bacchus, or Pan, led the way and plunged 
 into the Nile, and that the part of his body which was under the water assumed the form 
 of a fish, and the other part that of a goat ; and that to preserve the memory of this 
 frolic, Jupiter made him into a constellation, in his metamorphosed shape. 
 
 Some say that this constellation was the goat Amalthea, who supported the infan 
 Jupiter with her milk. To reward her kindness, the father of the gods placed her amonaf 
 the constellations, and gave one of her horns to the nymphs who had taken care of him 
 in his infantile years. This gift was ever after called the horn of plenty; as it possessed 
 the virtue of imparting to the holder whatever she desired. On this account the Latin 
 term Cornucopia, denotes plenty, or abundance of good things. The word Amalthea, 
 when used figuratively, has also the same meaning. 
 
 The real sense of tnis fable, divested of poetical embellishment, appears to be this ; 
 that in Crete, some say in Libya, there was a small territory shaped very much like ?. 
 bullock's horn, and exceedingly fertile, which the king presented to his daughter Amal- 
 thea, whom the poets feigned to have been Jupiter's nurse. 
 
 " The bounteous Pan," as he is styled by Milton, was the god of rural scenery, shep- 
 herds, and huntsmen. Virgil thus addresses him : 
 
 "And thou, the shepherd's tutelary god, 
 Leave, for a while, Pan ! thy loved abode." 
 
 The name of Pan is derived from a Greek word signifying aK things; and he was oftea 
 considered as the great principle of vegetable and ani-nal life. He resided chiefly in 
 Arcadia, in woods and the most rugged mountains. As Pan usually terrified the inhabi- 
 tants of the adjacent country, even when he was nowhere to be seen, that kind of fear 
 which often seizes men, and which is only ideal or imaginary, has received from him the 
 name of Panic. 
 
 Pales, the female deity corresponding to Pan, was the goddess of sheepfolds and of 
 pastures among the Romans. Thus Virgil : 
 
 " Now, sacred Pales, in a lofty strain, 
 1 sing the rural honors of thy reigu ' 
 
 The shepherds offered to this goddess milk and honey, to gain her protection over their 
 flocks. She is represented as an old woman, and was worshiped with great solemnity 
 at Rome. Her festivals, which were called Pulilia, were celebrated on the 20th of April, 
 the day on which Romulus laid the foundations of the city. 
 
 TELESCOPIC OBJECTS. 
 
 1. a CAPRICORNI A QUINTCPLE STAR in the right horn ; R. A. 20h. 09m. 10s. ; Dec. S. 13* 
 02' 1". A 3, pale yellow; B (or a 1) 4, yellow ; C 16, blue; D 9, ash-colored; E 91$, lilac 
 tinge. Few telescopes will reveal all these components. 
 
 2. j3 CAPRICORNI A wide PAIR OF STARS in the right horn, 2%" south-half-east of a; 
 R. A. 20h. 12m. Ols. ; Dec. S. 15 16' 9". A 3^, orange yellow; B 7, sky blue. Other 
 small stars in the field. It requires, a powerful instrument, and the most favorable cir- 
 cumstances to detect the minute star 5. (See Map VIII., Fig. 20.) 
 
 3. A GLOBULAR CLUSTER between Aquarius and the neck of Capricorn, 9 due east of 
 a Capricorni, about j from a 6th magnitude star; R. A. 20h. 44m. 89s. ; Dec. S. 13" 07' 
 6". Many stars in the field, two of which are close to the cluster, or the east. Map IX., 
 Fig. 63. 
 
 HISTORY. Who was Capricornus ? What proof cited? What further? What other 
 myth ? Meaning of this fable ? What said of Pales ? 
 
 TELESCOPIC OBJECTS. Alpha? Beta? Point out on the map ? What clusters? Where 
 nhown on the map ? 
 
PEGASUS 12 ( J 
 
 4. A fine PALB WHITK CLUSTER, about 20* west-northwest of Fomalh\ut; R. A. 21!^ 
 lira. 16s. ; Dec. S. 23* 68' 4"- A bright object, with straggling streams of stars, and but 
 few outliers in the field. Seen with small instruments. Map IX., Fig. 64. 
 
 CHAPTER XII. 
 
 CONSTELLATIONS ON THE MERIDIAN IN OCTOBER. 
 
 PEGASUS (THE FLYING HOESE). MAP II. 
 
 231. THIS constellation is represented in an inverted posture, 
 with wings. It occupies a large space in the heavens, between 
 the Swan, the Dolphin and the Eagle, on the west, and the Nor- 
 thern Fish and Andromeda, on the east. Its mean right ascen- 
 sion 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 meridian, 
 viz., from the 1st of October to the 10th of November. 
 
 232. We see but a part of Pegasus, the rest of the animal 
 being, as -the poets imagined, hid in the clouds. It is readily 
 distinguished from all other constellations 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 October, 
 and are 13 apart. The northern one, which is the brightest of three triangular stars 
 in the martingale, is of the 2d magnitude, and is called Scheat. Its declination is 26%. 
 Markab, also, of the 2d 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 already been described as 
 Alpheratz in the head of Andromeda, but it also belongs to this constellation, and is 14' 
 E. Scheat. 14* S. of Alpheratz, is Algenib, the last star in the wing.situated 16V E. of 
 Markab. 
 
 233. Algenib in Pegasus, Alpheratz in Andromeda, and Caph 
 in Cassiopeia are situated on the prime meridian, and point out 
 its direction through the pole. For this reason they are some- 
 times 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. 
 
 231. What constellations in this chapter? Describe Pegasus, its size, position, &c. 
 232. Do we see the whole of the figure ? How is it distinguished? What said of Scheat 
 and Markab? Of Alpheratz and Algenib? 233. Remark respecting Algenib, Alphe- 
 ratz and Caph? What sometimes called, and why? They form what? Remrke 
 
130 ASTRONOMY. 
 
 It is an arc of -the equinoctial ;olure which passes through the vernal equinox, n.ad 
 which the sun crosses about the 2 1st 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 degiees 
 from this prime meridian. 
 
 Enif, sometimes called Enir, is a star of the 3d magnitude in the nose of Pegaaus, 
 nbout 20* W. S. W. of Markab, and half-way between it and the Dolphin. About half of 
 the distance from Markab toward Enif, but a little to the S., there is a star of the 8d mag- 
 nitude situated in the neck, whose letter name is Zeta. The loose cluster directly S. c 
 the 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 tL/ee 
 are of the second magnitude and three of the third. 
 
 HISTORY. 
 
 This, according to fable, is the celebrated horse which sprung from the blood of Medusa, 
 after Perseus had cut off her head. He received his name according to Hesiod, from hig 
 being born near the sources (TTTJ'/IJ, Pege) of the ocean. According to Ovid, he fixed his 
 residence on Mount Helicon, where, by striking the earth with his foot, he raised the 
 fabled fountain called Hippocrene. He became the favorite of the Muses ; and being 
 tamed by Neptune or Minerva, he was given to Bellerophon, son of Glaucus, king of 
 Ephyre, to aid him in conquering the Chimsera, a hideous monster that continually vom- 
 ited flames. This monster had three heads, that of a lion, a goat, and a dragon. The 
 fore parts of its body were those of a lion, the middle those of a goat, and the hin ler 
 those of the dragon. It lived in Lycia, of which the top, on account of its desolate wil- 
 derness, was the resort of lions, the middle, which was fruitful, was covered with goats, 
 and at the bottom, the marshy ground abounded with serpents. Bellerophon was the 
 first who made his habitation upon it. 
 
 Plutarch thinks the Chimaera was the captain of some pirate who adorned their ship 
 with the images of a lion, a goat, and a dragon. 
 
 After the destruction of this monster, Bellerophon attempted to fly up to heaven upon 
 Pegasus ; but Jupiter was so displeased at this presumption, that he sent an insect to 
 sting the horse, which occasioned the melancholy fall of his rider. Bellerophon fell to 
 the earth, and Pegasus continued his flight up to heaven, and was placed by Jupiter 
 among the constellations. 
 
 " Now heav'n his further wand'ring flight confines, 
 Where, splendid with his num'rous stars, he shines." 
 
 OvWs fasti. 
 
 TELESCOPIC OBJECTS, 
 
 1. a PEGASI (Markab) A star with a distant companion, at the junction of the wing 
 and shoulder, 13" south of Scheat ; R. A. 22h. 56m. 47s. ; Dec. N. 14* 20' 08". A 2, white ; 
 B 11, pale grey. 
 
 2. /3 PEQASI (Sclieaf) A bright star with a minute distant companion, on the left fore- 
 leg; R. A. 22h. 56m. Ols. ; Dec. N. 27 13' 0". A 2, deep yellow ; B 15, blue ; with two 
 other stars in the field. 
 
 8. y PEGASI (Algenib) A star with a distant companion, on the edge of the wing; 
 R. A. Oh. 05m. Os. ; Dec. N. 14" 17' 07". A 2%, yellow ; B 13, pale blue. 
 
 4. e PEGASI (Enif) A star with two distant companions, in the nose of the figure ; 
 R. A. 21h. 36m. 19s. ; Dec. N. 9 08' 07". A 2%, yellow ; B 14, blue ; C 9, violet; and a 
 9th magnitude star of a viokt tinge, at a distance east. 
 
 5. (, PKGASI A star with a minute companion in the middle of the neck ; R. A. 22h. o<im- 
 29s. ; Dec. N. 9 59' 9". A line from Alpheratz over Markab, and carried 7 further, will 
 reach f. A3, light yellow; B 13, dusky; with other stars in the field. 
 
 6. A DOUBLE STAR between the head of Pegasus and the hind legs of the Fox ; or about 
 10 j* south by east of f Cygni; R. A. 21h. 14m. 41s. ; Dec. N. 19 07' 4". A 4, pale orange, 
 and considered variable ; B 9, purplish. 
 
 respecting the prime meridian ? What said of Enif? Of Zeta ? Of the head of Pegasus 
 Number of stars in the constellation, and their magnitudes? 
 
 HISTORY. Story of his origin and name ? Residence, <fec. ? How he came among tho 
 tars ? 
 
 TKLIMCOPIC OBJECTS. Alpha? Beta? Gamma? Epsilon? Zeta? What double starr 
 What cluster ? Point out on the map. What nebula ? 
 
AQUARIUS. 131 
 
 7. A GLOBULAR CLUSTKR between the mouths of Pegasus and Eqiileus, about 4* north- 
 west of e; R. A. 21h. 22m. 18s. ; Dec. N. 11 27' 4". Map IX., Fig. 65. It is laid down aa 
 l nebula on Map II., but with a good instrument it is resolved into stars, with straggling 
 outliers, as shown in the diagram. 
 
 8. An ELONGATED NEBULA in the animal's mane, about 3" due south of Markab ; R. A. 
 22h. 56m. 58s. ; Dec. N. 11" 27' 9'. A very faint and difficult object. 
 
 EQULEUS, YEL EQUI SECTIO (THE LITTLE HOBSE, OR THE 
 HORSE'S HEAD). MAP II. 
 
 234. This Asterism, or small cluster of stars, is situated about 
 1 W. of Enif, in the head of Pegasus, and about half-way 
 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 
 four 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-j- . Those in the nose are uppermost, being 4 N. of 
 those in the eyes. This figure also is in an inverted position. 
 These four stars are situated 10 or 12 S. E. of the diamond 
 in the Dolphin's head. Both of these clusters are noticeable on 
 account of their figure rather than their brilliancy. 
 
 HISTORY. 
 
 This constellation is supposed to be the brother of Pegasus, named Celeris, given by Mer- 
 cury to Castor, who was so celebrated for his skill in the management of horses ; others* 
 take him to be the celebrated horse which Neptune struck out of the earth with his tri- 
 dent, when he disputed with Minerva for superiority. The head only of Celeris is 
 visible, and this, also, is represented in an inverted position. 
 
 TELESCOPIC OBJECTS. 
 
 Four of the principal stars in this little group are double namely, /?, (J, and A. /3 
 is rather a star with a companion ; R. A. 21h/ 14m. 57s. ; Dec. N. 6* 07' 8". The other 
 three will easily be found from their proximity to 8. 
 
 AQUAEIUS (THE WATER-BEARER). MAP II. 
 
 235. This constellation is represented by the figure of a 
 pouring out water from an urn. It is situated in the Zodiac, 
 immediately S. of the equinoctial, and bounded by the Little 
 
 234. Situation of Eqiileus ? When on the meridian ? Number of stars, and how dJs- 
 linguished? What further description ? 
 
 HISTORY. What suppositions respecting the origin of Eqiileus ? 
 TKI.KSCOPIC OBJECTS. What double stars? How found"? 
 'i85. How ia Aquarius represented ? Its boundaries ? 
 
 6* 
 
132 ASTRONOMY. 
 
 Horse, Pegasus, and the Western Fish on the N. f the Whale O'l 
 the E., the Southern Fish on the S. and the Goat on the W. 
 
 236. Aquarius is now the 12th in order, or last of the 
 Zodiacal constellations ; and is the name of the llth sign in the 
 ecliptic. Its mean declination is 14 S., and its mean right 
 ascension 335, or 22 hours, 20 min. ; it being 1 hour and 40 
 min. W. of the equinoctial colure ; its center is, therefore, on 
 the meridian the 15th of October. 
 
 It contains one hundred and eight stars ; of which the four 
 largest are all of the 3d magnitude. 
 
 " His head, his shoulders, and his lucid breast, 
 Glisten with stars ; and where his urn inclines, 
 Rivers of light brighten the watery track." 
 
 237. The northeastern limit of Aquarius may be readily dis- 
 tinguished by means of four stars of the 4th magnitude, in the 
 hand and handle of the urn, so placed as to form the letter Y, 
 very plainly to be seen, 15 S. E. of JEnif, or 18 S. S. W. of 
 Markab, in Pegasus ; making with the two latter nearly a right 
 angle. 
 
 About 4J* W. of the figure is El Melik, a star of the 3d magnitude, in the E. shoulder, 
 and the principal one in this constellation. 10 S. W. of El Melik, is another star of the 
 Bame magnitude, situated in the W. shoulder, called Sad es Saud. 
 
 Ancha, of the 4th magnitude, is in the right side, 8* S. of El Melik. 9* E. of Ancha, is 
 another star of the 4th magnitude, whose letter name is Lambda. 
 
 iScheat, of the 3d magnitude, lying below the knee, is situated 8j* S. of Lambda; and 
 14 S. of Scheat, the brilliant star Fomalhaut, of between the 1st and 2d magnitudes, ter- 
 minates the cascade in the mouth of the Southern Pish. This star is common to both 
 these constellations, and is one of those from which the lunar distance is computed for 
 ascertaining the longitude at sea. It culminates at 9 o'clock on the 22d of October. 
 
 Fomalhaut, Deneh Kaitos, and Alpha in the head of the Phosnix, make a large triangle, 
 whose vertex is in Deneb Kaitos. Those two stars of the fourth magnitude, situated 4* 
 S. of Sad es Saud, and nearly the same distance from Ancha, 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 toward the tail of Cetus, from which the 
 cascade suddenly bends off near Scheat, in an opposite course, and finally disappears in 
 the mouth of the Southern Fish, 30 S. of Y. 
 
 HISTORY. 
 
 This constellation is the famous Ganymede, a beautiful youth of Phrygia, son of Tros, 
 king of Troy, or, 'according to Lucian, son of Dardanus. He was taken up to heaven by 
 Jupiter as he was tending his father's flocks on Mount Ida, and became the cup-bearer 
 of the gods in place of Hebe. There are various opinions, however, among the ancients 
 respecting its origin. Some suppose it represents Deucalion, who was placed among the 
 stars after the celebrated deluge of Thessaly, 1500 years before the birth of our Saviour ; 
 while others think it designed to commemorate Cecrops, who came from Egypt to Greece, 
 founded Athens, established science, and introduced the arts of polished life. 
 
 The ancient Egyptians supposed the setting or disappearance of Aquarius caused the 
 Nile to rise, by the sinking of his urn in the water. In the Zodiac of the Hebrews, 
 Aquarius represents the tribe of Reuben. 
 
 ts order in the signs and constellations ? Number and size of its stars ? 237. How 
 distinguish the northeast limit? What said of El Melik? Of Sad es Saud? Of Ancha., 
 Lambda, Scheat, &c. 
 
 HISTORY. Story of Ganymede, and Jupiter? What other myth? Idea of the EKVP 
 tain*? Hebrew Zodiac ? 
 
PISCES ATJSTRALIS. 
 
 TELESCOPIC OBJECTS. 
 
 1. a AV"ARII (PharcT) A star with a minute companion on the Water-bearer's left, 
 ahoulder; R A. 21h. 57m. 33s.; Dec. S. 1 05' 07*. A 3, pale yellow; B 13, grey; and 
 another star in the field on a line with A and B. Afarkab is on a line joining Alpheratz 
 nnd Phard, and about half way between them. 
 
 2. AQUARII (Sad-al-melik)^ star with a companion on the right shoulder ; R. A. 
 21h. 23m. 07s. ; Dec. N. 6 16' 04'. A 3, pale yellow ; B 15, blue. A very delicate object. 
 
 3. 7 AQUARII A delicate but wide DOUBLE STAR, on the water-pot; R. A. 22h. 13m. 
 '23s. ; Dec. S. 2" 11' 05". A 4, greenish tinge ; B 14, purple. It is about 4 east-by-south 
 from Sad-al-melik. 
 
 4. f AQUARII A BINARY STAR in the left wrist, about 6 east from Sadalmelik ; R. A. 
 22h. 20m. 35s. ; Dec. S. 0* 50' 02'. A 4, very white ; B 4^, white. 
 
 f>. T' AQUARII A fine DOUBLE STAR in the left leg, one third of the way from Fomalhaut 
 to Pegasi ; R. A. 22h. 39m. 13s. ; Dec. S. 14" 53' 09". A 6, white ; B 9J$, pale garnet. 
 
 6. i/>' AQUARII A DOUBLE STAR in the stream, being the first of three similar stars 
 marked ^1, ^a, i/,3 ; R. A. 23h. 07m. 80s. ; Dec. S. 9 57' 05". A 5%, orange tint ; B 9, sky 
 blue. It is about one-third of the way from Fomalhaut to a Andromedse. Several other 
 beautiful double stars east of Scheat, in the stream, as shown on the map. 
 
 T. A FINK GLOBULAR CLUSTER near the neck of Aquarius, about 5 north-half-east from 
 /9; R. A. 2th. 23m. 07s. ; Dec. S. 6 16' 04". A cluster of exceedingly small stars, which 
 has been likened to " a heap of fine sand." Several telescopic outliers in the field. Map 
 VIII., Fig. 66. 
 
 8. A PLANETARY NEBULA in the middle of the scarf; R. A. 20h. 55m. 27s. ; Dec. S. 11' 
 59' 08". About 12 east of a Capricorni, where a line from the Eagle's tail over 6 Anti- 
 noi, and as far again, reaches it. It is bright to its very disc, and but for itapale bluo 
 tint, would be a very miniature of Venus. 
 
 PISCES AUSTRALIS (THE SOUTHERN FISH). MAP II. 
 
 238. This constellation is directly S. of Aquarius, and is 
 represented as a fish drinking the water which Aquarius pours 
 from his urn. Its mean declination is 31 S. and its mean right 
 ascension and time of passing the meridian are the same as those 
 of .Aquarius, and it is seen on the meridian at the same time, 
 viz. on the 15th of October. It contains 24 visible stars, of 
 which one is of the 1st magnitude, or between the 1st and 2d, two 
 are of the 3d, and five of the 4th. The first and most beautiful 
 of all is Fomalhaut, situated in the mouth. This is 14 directly 
 S. of Scheat in Aquarius, and may be seen passing the meridian 
 low down in the southern hemisphere, on the 22d and 23d of 
 October. Its position in the heavens has been determined with 
 the greatest possible accuracy, to enable navigators to find their 
 longitude at sea. 
 
 The mode of doing this cannot be explained here. The proolen is one of some difficulty. 
 It consists in finding the angular distance between some star whose position is well known, 
 
 TELESCOPIC OBJECTS. Alpha? Beta? Gamma? Zeta? Tau? Psi? What clusters, 
 and where shown on the map ? What nebula? 
 
 233. Situation of Pisces Australia ? How represented ? When on the meridian ? Num- 
 ber of stars ? Magnitude ? The principal star ? How situated ? What use made of it? 
 What said of the method of finding the longitude by the moon and stars? 
 
134. ASTRONOMY. 
 
 and <Jie moon when she is passing near it; also, the altitude of each, at the same instant, 
 with good sextants. These data furnish the elements of a spherical triangle, the solution 
 of which, after various intricate corrections, is made to result in the longitude of the given 
 place. See note to Arietes. In 1714, the British Parliament offered a reward of 10,000 
 pounds sterling, to any man who should discover a method of determining the longitude 
 within 1, or 60 geographical miles of the truth ; 15,000 pounds to the man who shou.ll 
 find it within 40 miles, and 20,000 pounds, if found within 30 miles. These rewards in part, 
 have been since distributed among eminent mathematicians, in Europe, agreeably to the 
 respective merits of their discoveries. 
 
 HISTORY. 
 
 This constellation is supposed to have taken its name from the transformation of Venua 
 into the shape of a fish, when she fled, terrified at the horrible advances of the monster 
 Typhon, as we have related in the mythology of the Fishes. (See Pisces.) 
 
 TELESCOPIC OBJECTS. 
 
 a PISCES AUSTRALIS A first magnitude star with a very distant companion, in the eye 
 of the fish ; R. A. 22h. 48m. 48a. ; Dec. S. 80 28' 03'. A 1, reddish ; B 9 J<$, dusky blue. 
 
 LACERTA (THE LIZAED). MAP II. 
 
 239. This is a small and obscure modern constellation, between 
 the tail of Cygnus and the head of Andromeda. It has one star 
 of the 4th magnitude, eight of the 5th, and a few much smaller. 
 
 240. Between Lacerta and Andromeda a singular looking 
 figure appears on the map, called Gloria Frederica; or Frederics 
 Glory. It was inserted among the constellations by Bode, in 
 1787, as a compliment to Frederic II., of Prussia. It consists 
 of a crown, a laurel, a sword, and a pen, to represent the mon- 
 arch, the hero, the sage, and the pacificator. But the constel- 
 lation was not recognized by astronomers, and, as such, has 
 already passed from the heavens. 
 
 TELESCOPIC OBJECTS. 
 
 1. A neat DOCBLH STAR on the tip of the Lizard's tail ; R. A. 22h. llm. 56s. ; Dec. N. 
 86 58' 01'. A 6J$, pale white ; B 9, livid. 
 
 2. A delicate but wide DOUBLE STAR on the shoulder ; R. A. 22h. 14m. 25s. ; Dec. N. 45* 
 43' 09". A 5, pale yellow; B 13, orange tint. A line from Polaris carried by the east of 
 Cepheus tiara, and 11* further, will find it the lucida of a fine galaxy field. 
 
 8. A WIDE DOUBLE STAR near the end of the tail, the southern star of three forming a 
 neat triangle ; R. A. 22h. 82m. 05s. ; Dec. N. 38 13' 2". A 6%, white ; B 10, violet. 
 
 4. A DELICATI TRIPLE STAR in the space between the Lizard's back and the left hand of 
 Andromeda; R. A. 22h. 49m. 06s.; Dec. N. 40 45' 1". A 6, bright white; B. 15, pale 
 blue; C 9J6, reddish; a fourth star at a distance. A very difficult object; claimed by 
 Home for Andromeda, but usually classed as belonging to the Lizard. 
 
 HISTORY. Supposed origin of this constellation ? 
 
 TELESCOPIC OBJECTS. Alpha? Where situated? 
 
 239. Describe Lacerta. Where situated? 240. Whatother small constellation near P 
 By whom inserted, when and why? Of what does it consist? To represent what? Is it 
 recognized by astronomers ? 
 
 TELESCOPIC OBJECTS. What double stars in Lacerta T What triple star? Quadruple? 
 Cluster? Any of them shown on the map? 
 
VAR T ABLE AND DOUBLE STARS. 135 
 
 5. A QUADRUPLE STAR, the western one of the three forming the triangle at the end of 
 the tail ; R. A. 22h. 29m. 46s. ; Dec. N. 88 48' 5'. About 20 northwest of Alpheratz. A 
 and B 6J^, both white ; C 11, greenish ; D 10, blue. 
 
 6. A LARGB LOOSE CLUSTER in th ? Lizard's mouth ; R. A. v^h. 08m. 59s. ; Dec. N. 49' 05 
 1*. Stars from the 9th to the 14th magnitudes. -A line carried from Polaris through t'ut 
 tiara of Cepheus, and 8 beyond, strikes it. 
 
 CHAPTER XIII. 
 
 VARIABLE AND DOUBLE STARS CLUSTERS AND 
 NEBULAE. 
 
 241. THE periodical variations of brilliancy to which some of 
 the fixed stars are subject, may be reckoned among the most 
 remarkable of their phenomena. Several stars, formerly distin- 
 guished by their splendor, have entirely disappeared ; others are 
 now conspicuous which do not seem to have been visible to the 
 ancient observers ; and there are some which alternately appear 
 and disappear, or, at least, of which the light undergoes great 
 periodic changes. Some seem to become gradually more 
 obscure, as Delta in the Great Bear ; others, like Beta in the 
 Whale, to be increasing in brilliancy. 
 
 242. Some stars have all at once blazed forth with great splen- 
 dor, and, after a gradual diminution of their light, again become 
 extinct. The most remarkable instance of this kind is that of 
 the star which appeared in 1512, in the time of Tycho Brahe. 
 It suddenly shone forth in the constellation Cassiopeia, with a 
 splendor exceeding that of stars of the first magnitude, even of 
 Jupiter and of Yenus, at their least distances from the earth ; 
 and could be seen with the naked eye, on the meridian, in full 
 day! Its brilliancy gradually diminished from the time of its 
 first appearance, and at the end of sixteen months it entirely 
 disappeared, and has never been seen since. (See a more par- 
 ticular account of this phenomenon, page 35.^) 
 
 Another instance of the same kind was observed in 1604, when a star of the first mag- 
 nitude suddenly appeared in the right foot of Ophiuchus. It presented, like the former, 
 all the phenomena of a prodigious flame, being, at first, of a dazzling white, then of a 
 reddish yellow, and, lastly, of a leaden paleness ; in which its light expired. These 
 instances prove that the stars are subject to great physical revolutions. (Puge ()0) 
 
 243. A great number of stars have been observed whose lip-^it 
 seems to undergo a regular periodic increase and diminution. 
 
 241. What said of the periodical variations of the stars ? 242. What other remarka 
 ble phenomenon? What instances cited? What do these instances prove? 243. 
 
J 36 ASTRONOMY. 
 
 They are properly called Variable Stars. One in the Wfiak hab 
 a period of 344 days ".ad is remarkable for the magnitude of its 
 variations. From oeing a star of the second magnitude, it 
 becomes so dim as to be seen with difficulty through powerful 
 telescopes. Some are remarkable for the shortness of the. period 
 of their variation. Algol has a period of between two and three 
 days ; Delta Cephei, of 5^- days ; Beta Lyra, of 6 2-5 days ; 
 and Mu Antinoi, of 7 days. 
 
 The regular succession of these variations precludes the supposition of rn actual 
 destruction of the stars; neither can the variations be supposed to arise from a change 
 of distance ; for, as the stars invariably retain their apparent places, it would be neces- 
 sary to suppose that they approach to, and recede from the earth in straight lines, 
 irhich is very improbable. The most probable supposition is, that the stars revolve, like 
 the sun and planets, about an axis. "Such a motion," says the elder Herschel, "may 
 be as evidently proved, as the diurnal motion of the earth. Dark spots, or large por- 
 tions of the surface, less luminous than the rest, turned alternately in certain directions, 
 either toward 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 for any other cause.'' 
 
 DOUBLE STAKS. 
 
 244. On examining the stars with telescopes of considerable 
 power, many of them are found to be composed of two or more 
 stars, placed contiguous to each other, or of which the distance 
 subtends a very minute angle. This appearance is, probably, in 
 many cases, owing solely to the optical effect of their position 
 relative to the spectator ; for it is evident that two stars will 
 appear contiguous if they are placed nearly in the same line of 
 vision, although their real distance may be immeasurably grea^, 
 
 STARS OPTICALLY DOUBLE. 
 
 Apparent position. True position , 
 
 -* 
 
 B 
 
 Here the observer on the left sees a large and small star at A, apparently near toge- 
 therthe lowest star being much the smallest. But instead of their being situated as 
 tney appear to be, with respect to each other, the true position of the smaller star may 
 be at B instead of A; and the difference in their apparent magnitudes may be wholly 
 owing to the greater distance of the lower star. 
 
 Upon this subject Dr. Herschel remarks, that this nearness of the stars to each other, 
 in certain cases, might be attributed to some accidental cause, did it occur only in a few 
 instances ; but the frequency of this companionship, the extreme closeness, and, in 
 many cases, the near equality of the stars so conjoined, would alone lead to a strong 
 suspicion of a more near and intimate relation than mere casual juxtaposition. 
 
 245. There are, however, many instances in which the angle 
 of position of the two stars varies in such a manner as to indi- 
 
 arc these unsteady stars called ? What specimens referred to, and their periods ? What 
 does this regular succession, Ac., prove? What theory did Dr. Herschel adopt respect- 
 ing the variable stars? 244. What said of double stars? Are they always really near 
 each other? Illustrate on blackboard. Remark of Dr. llerschel? 245. Are they 
 
STARS OPTICALLY DOUBLE. 137 
 
 cate a revolution about each other and about a common center. 
 In this case they are said to form a Binary system performing to 
 each other the office of sun and planet, and are connected 
 together by laws of gravitation like those which prevail in the 
 solar system. 
 
 The recent observations of Sir John Herschel and Sir James South, hare established th- 
 .ruth of this singular fact beyond a doubt. Motions have been detected, so rapid as to 
 become measurable within very short periods of time ; and at certain epochs, the satellite 
 or feebler star has been observed to disappear, either passing behind or before the primary 
 or approaching so near to it that its light has been absorbed by that of the other. 
 
 246. The most remarkable instance of a regular revolution of 
 this sort, is that of Mizar, in the tail of the Great Bear ; in 
 which the angular motion is 6 degrees and 24 minutes of a great 
 circle, annually ; so that the two stars complete a revolution 
 about one another in the space of 58 years. About eleven 
 twelfths of a complete circuit have been already described since 
 its discovery in 1781, the same year in which the planet Herschel 
 was discovered. 
 
 A double star in Ophiuchus presents a similar phenomenon, and 
 the satellite has a motion in its orbit still more rapid. Castor 
 in the Twins, Gamma Virginis, Zeta in the Crab, Zi Bootis, 
 Delta Serpmtis, and that remarkable double star 61 Cygni f 
 together with several others, amounting to 40 in number, exhi- 
 bit the same evidence of a revolution about each other and about 
 a common center. (For a more particular description of these 
 stars, see Telescopic Objects and the Map.) 
 
 But it is to be remembered that these are not the revolutions of bodies of a planetary 
 nature around a solar center, but of sun around sun each, perhaps, accompanied by its 
 train of planets, and their satellites, closely shrouded from our view by the splendor of 
 their respective suns, and crowded into a space bearing hardly a greater proportion to 
 the enormous interval which separates them, than the distances of the satellites of our 
 planets from their primaries bear to their distances from the sun itself. 
 
 247. The examination of double stars was first undertaken by 
 the late Sir William Herschel, with a view to the question of 
 parallax. His attention was, however, soon arrested by the 
 new and unexpected phenomena which these bodies presented. 
 
 Sir William observed of them, in all, 2400. Sir James South and Herschel have given a 
 catalogue of 380 in the Transactions of the Royal Society for 1824, and South added 45S 
 in 1826. Sir John Herschel, in addition to the above, published an account of 1000, before 
 he left England for the Cape of Good Hope, where he went to push his discoveries in the 
 southern hemisphere. Professor Struve, with the great Dorpat telescope, has given a 
 catalogue of 3,063 of the most remarkable of these stars. 
 
 The object of these catalogues is not merely to fix the place of the star within such limits 
 KS will enable us easily to discover it at any future time, but also to record a description 
 
 jver really near each other? What motion ? What do these constitute? Is it certain 
 that stars are ever thus in motion around a common center ? 246. What remarkable 
 nstance cited? Its annual angular motion? Period? What Qther binary systems? 
 Are these planetary systems like our own ? 247. Who first undertook the examination 
 o.'t 1 ) double stars, and with what view? What number dul he observe? Wha* catu- 
 
ASTRONOMY. 
 
 of the appearance, position, and mutual distances of the individual stars composing the 
 system, in order that subsequent observers may have the means of detecting their con- 
 nected motions, or any changes which they may exhibit. Professor Struvj has also taken 
 notice of 52 triple stars, among which No. 11 of the Unicorn, Zeta of Cancer, and Zi of 
 the Balance, appear to be ternary systems in motion. Quadruple and quintuple stara 
 have likewise been observed, which also appear to revolve about a common center of 
 gravity; in short, every region of the heavens furnishes examples of these curious phe 
 nomena. 
 
 COLOR OF THE STARS. 
 
 248. Many of the double stars exhibit the curious and beau- 
 tiful phenomenon of contrasted colors, or complimentary tints. In 
 such instances, the larger star is usually of a ruddy or orango 
 hue, while the smaller one appears blue or green, probably in 
 virtue of that general law of optics, which provides that when 
 the retina is under the influence of excitement by any bright 
 colored light, feebler lights, which, seen alone, would produce no 
 sensation but that of whiteness, shall for the time appear 
 colored with the tint complimentary to that of the brighter. 
 
 Thus, a yellow color predominating in the light of the brighter star, that of the less 
 bright one, in the same field of view, will appear blue; while, if the tint of the brighter 
 star verge to crimson, that of the other will exhibit a tendency to green or even appear 
 a vivid green. The former contrast is beautifully exhibited by Iota, in Cancer ; the latter 
 by Al-tnaack, in Andromeda both fine double stars. If, however, the colored star be 
 much the less bright of the two, it will not materially affect the other. Thus, for instance, 
 Eta Oassiopeiae exhibits the beautiful combination of a large white star, and a small one 
 of a rich ruddy purple. 
 
 249. It is not easy to conceive what variety of illumination 
 two suns a red and a green, or a yellow and a blue one must 
 afford to a planet revolving about either ; and what charming 
 contrasts and grateful vicissitudes a red and a green day, for 
 instance, alternating with a white one and with darkness might 
 arise from the presence or absence of one or the other, or both, 
 above the horizon. 
 
 Insulated stars of a red color, almost as deep as that of blood, occur in many parts of 
 the hsavens, but no green or blue star (of any decided hue) has, we believe, ever beei. 
 noticed, unassociated with a companion brighter than itself. 
 
 CLUSTERS OF STARS. 
 
 250. When we cast our eyes over the concave surface of the 
 heavens in a clear night, we do not fail to observe that there are, 
 here and there, groups of stars which seem to be compressed 
 together more densely than those in the neighboring parts ; 
 forming bright patches or clusters. 
 
 ogues? Their object? What triple stars ? Ternary systems ? Quadruple stars, Ac ? 
 248. What said of the colors of the stars? What law of optics referred to? What illua- 
 'rations ? 24S. What remarks respecting red and green suns, <fec. ? Of insulated star; 
 of a red color f 250. What said of clusters T What specimen referred to ? Pleiades i 
 
NEBULA. 139 
 
 The Pleiades are an instance of this kind, in which six or 
 seven stars may be seen in near proximity, by the naked eye ; 
 and even more if the eye be turned carelessly upon it; for it is a 
 remarkable fact that the center of the eye is far less sensible to 
 feeble impressions of light, than the exterior portion of the retina. 
 Rheita affirms that by the aid of a telescope he counted over 200 
 stars in this small cluster. See Map VIII., Fig. 28. 
 
 In the constellation called Coma Berenices there is another group 
 more diffused, and consisting of much larger stars. In Cancer 
 there is a nebulous cluster of very minute stars, called Prasepe., 
 or the Beehive, which is sufficiently luminous to be seen by the 
 naked eye, in the absence of the moon, and which any ordinary 
 spyglass will resolve into separate stars. In the sword-handle 
 of Perseus, also, is another such spot, crowded with stars. It 
 requires, however, rather a better telescope to resolve it into 
 individual stars. See p. 65, and Map VIII., Fig. 39. 
 
 Whatever be the nature of these clusters, it is certain that other laws of aggregation 
 prevail in them, than those which have determined the scattering of starg over the gene- 
 ral surface of the sky. Many of them, indeed, are of an exactly round figure, and con- 
 vey the idea of a globular space filled full of stars, and constituting, in itself, a family or 
 society apart, and subject only to its own internal laws. 
 
 '' It would be a vain task," says the younger Herschel, " to attempt to count the stara 
 in one of these globular clusters. They are not to be reckoned by hundreds ; for it would 
 appear that many clusters of this description must contain, at least, ten or twenty thou- 
 rvnd stars, compacted and wedged together in a round space, not more than a tenth part 
 as la/** as that which is covered by the moon. 
 
 NEBULAE. 
 
 251. The Nebula, so called from their dim, cloudy appearance, 
 form another class of objects which furnish matter for curious 
 speculation and conjecture respecting the formation and struc- 
 ture of the sidereal heavens. When examined with a telescope 
 of moderate powers, the greater part of the nebulae are dis- 
 tinctly perceived to be composed of little stars, imperceptible to 
 the naked eye, because, on account of their apparent proximity, 
 the rays of light proceeding from each are blended together, in 
 such a manner as to produce only a confused luminous appear- 
 ance. 
 
 In other nebulae, however, no individual stars can be perceived, even through the best 
 telescopes ; and the nebulae exhibit only the appearance of a self-luminous phosphores- 
 cent patch of gaseous vapor, though it is possible that even in this case, the appearance 
 may be owing to a congeries of stars so minute, or so distant, as not to afford, singly, 
 sufficient light to make an impression on the eye. 
 
 Remarks upon their nature and the laws that govern them? Remarks of Herschel? 
 251. What are nebula, and why so called ? How appear through telescopes? Are they 
 all resolvable into stars ? 
 
140 ASTRONOMY. 
 
 252. One of the most remarkable nebulaa is in the sword- 
 handle of Orion. It is formed of little flocky masses, like wisps 
 of cloud, which seem to adhere to many small stars at its out- 
 skirts. It is not very unlike the mottling of the sun's disc, but 
 of a coarser grain, and with darker intervals. These wisps of 
 light, however, present no appearance of being composed of 
 small stars ; but in the intervals between them, we fancy that 
 we see stars, or that, could we strain our sight a little more, we 
 should see them. These intervals may be compared to openings 
 in the firmament, through which, as through a window, we seem 
 to get a glimpse of other heavens, and brighter regions, beyond. 
 See page 45, and Map VIII., Fig. 32. 
 
 253. Another very remarkable nebula is that in the girdle of 
 Andromeda, which, on account of its being visible to the naked 
 eye, has been known since the earliest ages of astronomy. It is 
 often mistaken for a comet, by those unacquainted with the 
 heavens. See page 20, and Map VIII., Fig. 22. 
 
 Marias, who noticed it in 1612, describes its appearance as that of a candle shining 
 through horn ; and the resemblance is certainly very striking. Its form is a long oval, 
 increasing, by insensible gradations of brightness, from the circumference to a central 
 point, which, though very much brighter than the rest, is not a star, but only a nebula in 
 a high state of condensation. It occupies an area comparatively large equal to that 
 of the moon in quadrature. This nebula may be considered as a type, on a large scale, 
 of a very numerous class of nebulae, of a round or oval figure, increasing more or Ja? in 
 density toward the center. 
 
 254. Annular nebula are those in the form of a ring, but are 
 among the rarest objects in the heavens. The most conspicuous 
 of this class is to be found exactly half-way between the stars 
 .Beta and Gamma Lyrae, and may be seen with a telescope of 
 moderate power. It is small, and particularly well denned ; 
 appearing like a flat oval ring. The central opening is not 
 entirely dark, but is filled with a faint, hazy light, uniformly 
 spread over it, like a fine gauze stretched over a hoop. 
 
 255. Planetary nebula are very extraordinary objects. They 
 have, as their name imports, the appearance of planets, with 
 round or slightly oval discs, somewhat mottled, but approaching, 
 in some instances, to the vividness of actual planets. Some of 
 them, upon the supposition that they are equally distant from us 
 with the stars, must be of enormous magnitude. That one, for 
 instance, which is situated in the left hand of Aquarius, must 
 
 252. What remarkable nebula mentioned? Describe it? Point out on the map. 
 258. What other? How long known, and why? Show on the map. How described by 
 Alarms? Its form and extent? How considered? 254. What are Annular NebidcK ? 
 t>re they common? What specimen referred to? 255. Planetary nebulae? Their 
 aharacter and magnitude ? Specimen? Stellar nebulae ? General remarks respecting 
 
VIA LACTEA. 141 
 
 bave a volume vast enough, upon the lowest computation, to fill 
 the whole orbit of Herschel I 
 
 In some instances a nebula presents the appearance of a faint, 
 luminous atmosphere, of a circular form, and of large extent, 
 surrounding a central star of considerable brilliancy. These are 
 denominated Stellar Nebula. 
 
 The nebulae furnish an inexhaustible field of speculation and conjecture. That by far 
 the larger number of them consists of stars, there can be little doubt; and in the inter- 
 minable range of system upon system, and firmament upon firmament, which we thus 
 catch a glimpse of, the imagination is bewildered and lost. Sir William Herschel con- 
 jectured that the nebuUe might form the material out of which nature elaborated new 
 suns and systems, or replenished the wasted light of older ones. But the little we know 
 of the physical constitution of these sidereal masses, is altogether insufficient to warrant 
 Buch a conclusion. (For a Spiral Nebula recently discovered by Lord Rosse, see Map IX. 
 Fig. 68.) 
 
 CHAPTER XIY. 
 
 YIA LACTEA (THE MILKY-WAT). 
 
 " Throughout the Galaxy's extended line, 
 TJnnumber'd orbs in gay confusion shine : 
 Where every star that gilds the gloom of night 
 With the faint tremblings of a distant light, 
 Perhaps illumes some system of its own, 
 With the strong influence of a radiant sun." Mrs. Carter. 
 
 256. THE YIA LAC.TEA, or Milky-Way, is that luminous zone 
 or pathway of singular whiteness, varying from 4 to 20 in 
 width, which passes quite around the heavens. The Greeks 
 called it GALAXY, on account of its color and appearance : the 
 Latins, for the same reason, called it YIA LACTEA, which, in our 
 tongue, is Milky-Way. 
 
 Of all the objects which ths heavens exhibit to our view, this fills the mind with the 
 most indescribable grandeur and amazement. When we consider what unnumbered 
 millions of mighty suns compose this stupendous girdle, whose distance is so vast that 
 the strongest telescope can hardly separate their mingled twilight into distinct specks, 
 and that the most contiguous of any two of them may be as far asunder as our sun is 
 from them, we fall as far short of adequate language to express our ideas of such immen- 
 uity, as we do of instruments to measure its boundaries. 
 
 ' 257. It is one of the achievements of astronomy that has 
 resolved the Milky-Way into an infinite number of small stars, 
 whose confused and feeble luster occasions that peculiar white- 
 ness which we see in a clear evening, when the moon is absent. 
 It is also a recent and well-accredited doctrine of astronomy., 
 
 the Nebulae? Sir Wm. Herschel's conjecture? 256. What is the Via Lactea? Its 
 Greek name? What said of its magnificence and grandeur? 25T. What said of the 
 achievements of astronomy j 1 Its doctrine respecting the structure of the aciverk;i? 
 Of the sun, and its relation to the fixed stars? 
 
142 ASTRONOMY. 
 
 that all the stars in the universe are arranged into clusters, 01 
 groups, which are called NEBULA or STARRY SYSTEMS, each of 
 which consists of myriads of stars. 
 
 The fixed star which we call OUR SUN, belongs, it is said, to that extensive nebula, th<s 
 Milky- Way; and although apparently at such an inmeasurable distance from its fellows 
 is, doubtless, as near to any one of them, as they are to one another. 
 
 258. Of the number and economy of the stars which compose 
 this group, we have very little exact knowledge. Dr. Herschel 
 informs us that, with his best glasses, he saw and counted 588 
 stars in a single spot, without moving his telescope ; and as the 
 gradual motion of the earth carried these out of view and intro- 
 duced others successively in their places, while he kept his tele- 
 scope steadily fixed to one point, " there passed over his field 
 of vision, in the space of one quarter of an hour, no lest than 
 one hundred and sixteen thousand stars, and at another time, in 
 forty-one minutes, no less than two hundred and fifty-eight thou- 
 sand." 
 
 In *,11 parts of the Milky- Way he found the stars unequally dispersed, and appearing 
 to arrange themselves into separate clusters. In the small space for example, between 
 Beta and Sad'r, in Cygni, the stars seem to be clustering in two divisions ; each division 
 conta Jiing upwards of one hundred and sixty-five thousand stars. At other observations, 
 when examining a section of the Milky- Way, not apparently more than a yard in breadth, 
 and six in length, he discovered fifty thousand stars, large enough to be distinctly 
 count id ; and he suspected twice as many more, which, for want of sufficient light in his 
 telescope, he saw only now and then. 
 
 259. It appears from numerous observations, that various 
 changes are taking place among the nebulae that several nebu- 
 las are formed by the disolution of larger ones, and that many 
 nebulae of this kind are at present detaching themselves from 
 the Milky-Way. In that part of it which is in the body of 
 Scorpio, ihere is a large opening, about 4 broad, almost desti 
 tute of stars. These changes seem to indicate that mighty 
 movements and vast operations are continually going on in the 
 distant regions of the universe, upon a scale of magnitude and 
 grandeur which baffles the human understanding. 
 
 More than two thousand five hundred nebulae have already been observed ; and, if 
 each of them contains as many stars as the Milky-Way, several hundreds of millions of 
 stars must exist, even within that portion of the heavens which lies open to our obser- 
 vation. 
 
 " what a confluence of ethereal fires. 
 From urns unnumber'd down the steep of heaven 
 Streams to a point, and centers on my sight." 
 
 260. Although the Milky-Way is more or less visible at all 
 seasons of the year, yet it is seen to the best advantage during 
 
 258. Number and economy of the stars? Dr. Herschel's statements? What number 
 passed the field of his instrument in a quarter of an hour? In forty-one minutes? In 
 space apparently only a yard in breadth? 259. What changes observed in the nebu- 
 las? What do they indicate? Number of nebulae? Estimated number of stars? 
 ^60. When is the Via Lactea tn to the best advantage? Direction when Lyra is on the 
 
ORIGIN OF THE CONSTELLATIONS 143 
 
 the months of July, August, September, and October, When 
 Lyra is on, or near the meridian, it may be seen stretching 
 obliquely over the heavens from northeast to southwest, gradu- 
 ally moving over the firmament in common with other constel- 
 lations. (For views of our cluster, see Map IX., Figs. 69, 70, 71.) 
 
 Its form, treadth and appearance are various, indifferent parts of its course. In some 
 places it is dense and luminous ; in others, it is scattered and faint. Its breadth is often 
 not more than five degrees ; thouph sometimes it is ten or fifteen degrees, and even 
 twenty. In some places it assumes a Double path, but for the most part it is single. 
 
 It may be traced in the heavens, beginning near the head of Cepheus, about 30 from 
 the north pole, through the constellations Cassiopeia, Perseus, Auriga, and part of Orion 
 and the feet of Gemini, where it crosses the Zodiac ; thence over the equinoctial into 
 the southern hemisphere, through Monoceros, and the middle of the ship Argo, where it 
 is most luminous, Charles' Oak, the Cross, the feet of the Centaur, and the Altar. Here 
 it is divided into two branches, as it passes over the Zodiac again into the northern hem- 
 isphere. One branch runs through the tail of Scorpio, the bow of Sagittarius, the shield 
 of Sobieski, the feet of Antinous, Aquila, Delphinus, the Arrow and the Swan. Th'i other 
 branch passes through the upper part of the tail of Scorpio, the side of Serpentarius, 
 Taurus Poniatowskii, the Goose and the neck of the Swan, where it again unites with the 
 other branch, and passes on to the head of (Jepheus, the place of its beginning. 
 
 Some of the pagan philosophers maintained that the Milky- Way was formerly the sun's 
 path, and that its present luminous appearance is the track which its scattered beams 
 left visible in the heavens. 
 
 The ancient poets, and even philosophers, speak of the Galaxy, or Milky-Way, as the 
 path which their deities used in the heavens, and which led directly to the throne of 
 Jupiter. Thus, Ovid, in his Metamorphoses, Book i. : 
 
 " A way there is in heaven's extended plain, 
 Which, when the skies are clear, is seen below, 
 And mortals, by the name of Milky, know ; 
 The groundwork is of stars, through which the road 
 Lies open to the Thunderer's abode." 
 
 Milton alludes to this in the following lines : 
 
 " A broad and ample road, whose dust is gold, 
 And pavement, stars, as stars to thee appear, 
 
 Seen in the Galaxy, that Milky- Way, * 
 
 Which nightly as a circling zone, thou seest 
 Powdered with stars." 
 
 CHAPTER XY. 
 
 ORIGIN OF THE CONSTELLATIONS. 
 
 261. THE science of astronomy was cultivated by the imme- 
 diate descendants of Adam. JOSEPHUS informs us that the sons 
 of SETH employed themselves in the study of astronomy ; and 
 that they wrote their observations upon two pillars, one of brick 
 
 meridian? Its form, breadth, &c.? How traced in the heavens? Notion of the Pagan 
 philosophers ? Of the poets ? What citations ? 261. How early was astronomy cultivated ? 
 
i4i ASTRONOMY. 
 
 am the other of stone,* in order to preserve them against the 
 destruction which A DAM had foretold should come upon the earth. 
 
 He also relates, that Abraham argued the unity and poorer of God, from the orderly 
 course of things both at sea and land, in their times and seasons, and from his observa- 
 tions upon the motions and influences of the sun, moon and stars ; and that he read lec- 
 tures in astronomy and arithmetic to the Egyptians, of which they understood nothing 
 till Abraham brought these sciences from Chaldea to Egypt ; from whence they passed ti> 
 the Greeks. 
 
 262. BEROSUS also observes that Abraham was a great and just 
 man, and famous for his celestial observations'; the making of 
 which was thought to be so necessary to the human welfare, that 
 he assigns it as the principal reason of the Almighty's prolong- 
 ing the life of man. 
 
 This ancient historian tells us, in his account of the longevity of the antediluvians, 
 that Providence found it necessary to prolong man's days, in order to promote the study 
 and advancement of virtue, and the improvement of geometry and astronomy, which 
 required, at least, six hundred years for making and perfecting observations.t 
 
 263. When Alexander took Babylon, Calisthenes found that 
 the most ancient observations existing on record in that city, 
 were made by the Chaldeans about 1903 years before that period, 
 which carries us back to the time of the dispersion of mankind 
 by the confusion of tongues. It was 1500 years after this that 
 the Babylonians sent to Hezekiah, to inquire about the shadow's 
 going back on the dial of Ahaz. 
 
 It is, therefore, very probable that the Chaldeans and Egyptians were the original 
 inventors of astronomy; but at what period of the world they marked out the heavens 
 into constellations, remains in uncertainty. La Place fixes the date thirteen or fourteen 
 hundred years before the Christian era, since it was about this period that Eudoxus con- 
 structed the first celestial sphere upon which the constellations were delineated. Sir 
 Isaac Newton was of opinion, that all the old constellations related to the Argonautic 
 expedition, and that they were invented to commemorate the heroes and events of that 
 memorable enterprise. It should be remarked, however, that while none of the ancient 
 constellations refer to transactions of a later date, yet we have various accounts of them 
 of a much higher antiquity than that event. 
 
 264. Some of the most learned antiquarians of Europe have 
 searched every page of heathen mythology, and ransacked all 
 the legends of poetry and fable for the purpose of rescuing this 
 subject from that impermeable mist which rests upon it, and 
 they have only been able to assure us, in general terms, that 
 they are Chaldean or Egyptian hieroglyphics, intended to per- 
 petuate, by means of an imperishable record, the memory of the 
 times in which their inventors lived, their religion and manners, 
 
 * Josephus affirms, that "he saw himself that of stone to remain in Syria in his ow) 
 time." 
 t Vince's Complete System of Astronomy, Vol. ii. p. 244. 
 
 What proof? What said of Abraham? 262. What further proof? What reason 
 assigned for the longevity of the antediluvians? 263. What discovery by Calisthenes ? 
 What conclusion from this discovery ? La Place's date of the origin of the constdla 
 Uocs? Sir Isaac Newton's opinion? Remark? 264. What researches, and wba', 
 results? 
 
ORIGIN OF THE CONSTELLATIONS. 145 
 
 their achievements in the arts, and whatever in theh 1 history was 
 nost worthy of being commemorated. There was, at least, a 
 moral grandeur in this idea ; for an event thus registered, a 
 custom thus canonized, or thus enrolled among the stars, must 
 needs survive all other traditions of men, and stand forth in per- 
 petual characters to the end of time. 
 
 265. In arranging the constellations of the Zodiac, for instance, 
 it would be natural for them, we may imagine, to represent 
 those stars which rose with the sun in the spring of the year, by 
 such animals as the shepherds held in the greatest esteem at that 
 season ; accordingly, we find Aries, Taurus, and Gemini, as the 
 symbols of March, April, and May. 
 
 266. When the sun enters the sign Cancer, at the summer 
 solstice, he discontinues his progress towards the north pole, and 
 begins to return towards the south pole. This retrograde mo- 
 tion was fitly represented by a Crab, which is said to go back- 
 ward. The sun enters this sign about the 22d of June. 
 
 The heat which usually follows in the next mouth was repre- 
 sented by the Lion ; an animal remarkable for its fierceness, 
 and which at this season was frequently impelled by thirst tc 
 leave the sandy desert, and make its appearance on the banks 
 of the Nile. 
 
 267. The sun entered the sixth sign about the time of harvest, 
 which season was therefore represented by a Virgin, or female 
 reaper, with an ear of corn in her hand. 
 
 At the autumnal equinox, when the sun enters Libra, the 
 days and nights are equal all over the world, and seem to 
 observe an equilibrium or balance. The sign was therefore 
 represented under the symbol of a pair of Scales. 
 
 268. Autumn, which produces fruit in great abundance, brings 
 with it a variety of diseases, and on this account was represented 
 by that venomous animal, the Scorpion, which, as he recedes, 
 wounds with a sting in his tail. The fall of the leaf, was the 
 season for hunting, and the stars which mark the sun's path at 
 this time were represented by a huntsman, or archer, with his 
 arrows and weapons of destruction. 
 
 The Goat, which delights in climbing and ascending some 
 mountain or precipice, is the emblem of the winter solstice, when 
 the sun begins to ascend from the southern tropic, and gradually 
 to. increase in height for the ensuing half year. 
 
 265. Origin of Aries, Taurus, and Gemini? 266. Of Cancer and Leo 2C7. 0' 
 Virgo aud Libra T 268. O f Scorpio aud Capricorn ? 
 
1 46 ASTRONOMY. 
 
 269. Aquarius, or the Water Bearer, is represented by the 
 figure of a man pouring out water from an urn, an emblem of 
 the dreary and uncomfortable season of winter. 
 
 The last of the zodiacal constellations was Pisces, or a couple 
 of fishes, tied back to back, representing the fishing season. 
 The severity of winter is over ; the flocks do not afford suste- 
 nance, but the seas and rivers are open and abound with fish. 
 
 " Thus monstrous forms, o'er heaven's nocturnal arch, 
 Seen by the sage, in pomp celestial march ; 
 See Aries there his glittering bow unfold, 
 And raging Taurus toss his horns of gold ; 
 With bended bow the sullen Archer lowers, 
 And there Aquarius comes with all his showers ; 
 Lions and Centaurs, Gorgons, Hydras rise, 
 And gods and heroes blaze along the skies." 
 
 Whatever may have led to the adoption of these rude names at first, they are now 
 retained to avoid confusion. 
 
 The early Greeks, however, displaced many of the Chaldean constellations, and sub- 
 stituted such images in their place as had a more special reference to their own history. 
 The Romans also pursued the same course with regard to their history; and henci tho 
 contradictory accounts that have descended to later times. 
 
 270. Some, moreover, with a desire to divest the science of 
 the stars of its pagan jargon and profanity, have been induced 
 to alter both the names and figures of the constellations. In 
 doing this, they have, committed the opposite fault ; that of 
 blending them with things sacred. 
 
 The " venerable Bede," for example, instead of the profane 
 names and figures of the twelve constellations of the Zodiac, 
 substituted those of the twelve apostles. Julius Schillerius, fol- 
 lowing his example, completed the reformation in 1627, by giv- 
 ing Scripture names to all the constellations in the heavens. 
 
 Weigelius, too, a celebrated professor of mathematics in the University of Jena, made 
 a new order of constellations, by converting the firmament into a COSLUM HERALDICUM, in 
 which he introduced the arms of all the princes of Europe. But astronomers, generally, 
 never approved of these innovations ; and for ourselves, we had as lief the sages and 
 heroes of antiquity should continue to enjoy their fianced honors in the sky, as to see 
 their places supplied by the princes of Europe. 
 
 271. The number of the old constellations, including those of 
 the Zodiac, was only forty-eight. As men advanced in the 
 knowledge of the stars, they discovered many, but chiefly in 
 southern latitudes, which were noc embraced in the old constel- 
 lations, and hence arose that mixture of ancient and moderr 
 names which we meet with in modern catalogues. 
 
 272. Astronomers divide the heavens into three parts, called 
 the Northern and Southern Hemispheres, and the Zodiac. In the 
 
 269. Of Aquarius and Pisces? Course of the Greeks and Romans, in displacing con- 
 stellations? 270. What other reform attempted? What particular instances cited! 
 Bede ? Schillerius ? Weigelius ? How are these innovations regarded by astronomers 
 211. Number of the old constellations? How others added? 272. How do astrono 
 
ORIGIN OF THE CONSTELLATIONS. 147 
 
 northern hemisphere, astronomers usually reckon thirty-four con- 
 stellations, in the Zodiac twelve, and in the southern hemisphere 
 forty-seven ; making in all ninety-three. Besides these, there 
 are a few of inferior note, recently formed, which are not con- 
 sidered sufficiently important to be particularly described. 
 
 273. About the year 160*3, John Bayer, a native of Germany, 
 invented the convenient system of denoting the stars in each 
 constellation by the letters of the Greek alphabet, applying to 
 the largest star the first letter of the alphabet ; to the next 
 largest the second letter, and so on to the last. Where there 
 are more stars in the constellation than there are Greek letters, 
 the remainder are denoted by the letters of the Roman alphabet, 
 and sometimes by figures. 
 
 By this system of notation, it is now as easy to refer to any particular star in the 
 heavens, as to any particular house in a populous c'ty, by its street and number. Before 
 this practice was adopted, it was customary to denote the stars by referring them to 
 their respective situations in the figure of the constellation to which they severally 
 belonged, as the head, the arm, the foot, &c. 
 
 It is hardly necessary to remark that these figures, which are all very curiously depicted 
 upon artificial globes and maps, are purely a fanciful invention answering many con- 
 venient ends, however, for purposes of reference and classification, as they enable us to 
 designate with facility any particular star, or cluster of stars ; though these clusters 
 very rarely, if ever, represent the real figures of the objects whose names they bear. 
 And yet it is somewhat remarkable that the name of " Great Bear," for instance, should 
 have been given to the very same constellation by a nation of American aborigines (the 
 Iroquois), and by the most ancient Arabs of Asia, when there never had been any com- 
 munication between them ! Among other nations, also, between whom there exists no 
 evidence of any intercourse, we find the Zodiac divided into the same number of constel- 
 lations, and these distinguished by nearly the same names, representing the twelve 
 months, or seasons of the year. 
 
 274. The constellations, or the uncouth figures by which they 
 are represented, are a faithful picture of the ruder stages of 
 civilization. They ascend to times of which no other record 
 exists ; and are destined to remain when all others shall be lost. 
 Fragments of history, curious dates and documents relating to 
 chronology, geography and languages, are here preserved in 
 imperishable characters. 
 
 The adventures of the gods, and the inventions of men, the exploits of heroes, and 
 the fancies of poets, are here spread out in the heavens, and perpetually celebrated before 
 all nations. The Seven stars, and Orion, present themselves to us, as they appeared to 
 Amos and Homer: as they appeared to Job, more than 3000 years ago, when the 
 Almighty demanded of him " Knowest thou the ordinances of heaven? Canst thou 
 bind the sweet influences of the PLEIADKS, or loose the bands of ORION? Canst thou 
 bring forth MAZZAROTH in his season, or canst thou guide ARCTURUS with his sons?" 
 Here, too, are consecrated the lyre of Orpheus and the ship of the Argonauts ; and, in 
 the same firmament, glitter the Mariner's Compass and the Telescope of Herschel. 
 
 mers divide the constellations? Number in each division? Total? What other* . 
 2T3. John Bayer's invention? Utility of it? How before it was adopted r What remark 
 respecting the figures on maps and globes, and their use? What remarkable facto 
 etatcd? 274. Historical use of the constellations? Illustrations? 
 
 B.G. 
 
148 ASTRONOMY. 
 
 CHAPTER XVI. 
 NUMBER, DISTANCE AND ECONOMY OF THE STARS. 
 
 275. THE first conjecture in relation to the distance of the 
 fixed stars is, that they are all placed at an equal distance from 
 the observer, upon the visible surface of an immense concave 
 vault, which rests upon the circular boundary of the world, and 
 which we call the Firmament. We can, with the unassisted eye, 
 form no estimate of their respective distances ; nor has the tele- 
 scope yet enabled us to arrive at any exact results on this sub- 
 ject, although it has revealed to us many millions of stars that 
 are as far removed beyond those which are barely visible to the 
 naked eye, as these are from us. 
 
 Viewed through the telescope, the heavens become quite another spectacle not only 
 to the understanding but to the senses. New worlds burst upon the sight, and old onea 
 expand to a thousand times their former dimensions. Several of those little stars which 
 but feebly twinkle on the unassisted eye, become immense globes, with land and water, 
 mountains and valleys, encompassed by atmospheres, enlightened by moons, and diver- 
 sified by day and night, summer and winter. 
 
 Beyond these are other suns, giving light and life to other systems, not a thousand, or 
 two thousand merely, but multiplied without end, and ranged all around us, at immense 
 distances from each other, attended by ten thousand times ten thousand worlds, all in 
 rapid motion ; yet calm, regular and harmonious all space seems to be illuminated, and 
 every particle of light a world. 
 
 276. It has been computed that one hundred millions of stars 
 which cannot be discerned by the naked eye, are now visible 
 through the telescope. And yet all this vast assemblage of suns 
 and worlds may bear no greater proportion to what lies beyond 
 the utmost boundaries of human vision, than a drop of water to 
 the ocean ; and, if stricken out of being, would be no more 
 missed, to an eye that could take in the universe, than the fall 
 of a single leaf from the forest. 
 
 We should therefore learn, says Dr. Chalmers, not to look on our earth as the universe 
 of God, but as a single, insignificant atom of it ; that it is only one of the many mansions 
 which the Supreme Being has created for the accommodation of his worshipers ; and 
 that he may now be at work in regions more distant than geometry ever measured, creat- 
 ing won Is more manifold than numbers ever reckoned, displaying his goodness, and 
 spreading over all the intimate visitations of his care. 
 
 277. The immense distance at which the nearest stars are 
 known to be placed, proves that they are bodies of a prodigious 
 size, not inferior to our sun, and that they shine, not by reflected 
 rays, but by their own native light. It is therefore concluded, 
 
 275. What is the first conjecture as to the distance of the stars? Can we form no jus! 
 estimate? What said of the heavens when seen through a telescope? 276. What 
 computation as to ths number of stars invisible to the naked eye, but visible through 
 tt.lcscopce? Is this probably the whole universe ? Remark of Chalmers? 277. Whar 
 
NUMBER, DISTANCE, AND EC NOMY OB THE STARS. 149 
 
 with good reason, that every fixed star is a sun, no less spacious 
 than ours, surrounded by a retinue of planetary worlds, which 
 revolve around it as a center, and derive from it light and heat, 
 and the agreeable vicissitudes of day and night. 
 
 These vast globes of light, then, could never have been designed merely to diversify 
 the voids of infinite space, nor to shed a few glimmering rays on our far distant world, 
 for the amusement of a few astronomers, who, but for the most powerful telescopes, had 
 never seen the ten thousandth part of them. We may therefore rationally conclude, tha: 
 wherever the All-wise Creator has exerted his creative power, tJiere also he has placed 
 intelligent beings to adore his goodness. 
 
 278. The greatest possible ingenuity and pains have been 
 taken by astronomers to determine, at least, the approximate 
 distance of the nearest fixed stars. If they have hitherto been 
 unable to arrive at any satisfactory result, they have, at least, 
 established a limit beyond which the stars must necessarily be 
 placed. If they have failed to calculate their true distances 
 from the earth, it is because they have not the requisite data. 
 The solution of the problem, if they had the data, would not be 
 more difficult than to compute the relative distances of the 
 planets a thing which any schoolboy can do. 
 
 In estimating so great a distance as the nearest fixed star, it is necessary that we 
 employ the longest measure which astronomy can use. Accordingly, we take the whole 
 diameter of the earth's orbit, which, in round numbers, is 190 millions of miles, and 
 endeavor, by a simple process in mathematics, to ascertain how many measures of this 
 length are contained in the mighty interval which separates us from the stars. 
 
 The method of doing this can be explained to the apprehension of the pupil, if he doe* 
 not shrink from the illustration, through an idle fear that it is beyond his capacity. 
 
 For example ; suppose that, with an instrument constructed for the purpose, we should 
 this night take the precise bearing or angular direction from us of some star in the 
 northern hemisphere, and note it down with the most perfect exactness, and, having 
 waited just six months, when the earth shall have arrived at the opposite point of its 
 orbit, 190 millions of miles east of the place which we now occupy, we should then repeat 
 our observation upon the same star, and see how much it had changed its position by 
 our traveling so great a distance one side of it. Now, it is evident, that if it changes its 
 apparent position at all, the quantity of the change will bear some proportion to the 
 distance gone over ; that is, the nearer the star, the greater the angle ; and the more 
 remote the star, the less the angle. It is to be observed, that the angle thus four'!, i? 
 called the star's Annual Parallax. 
 
 279. But it is found by the most eminent astronomers of the 
 age, and the most perfect instruments ever made, that the paral- 
 lax of the nearest stars does net exceed ihefour thousandth part 
 of a degree, or a single second ; so that, if the whole great orbit 
 of the earth were lighted up into a globe of fire 600 millions of 
 miles in circumference, it would be seen by the nearest star only 
 as a twinkling atom ; and to an observer placed at this distance, 
 
 proof that the stars are large bodies? What conclusion, therefore? What other 
 inference ? 278. What effort to determine the distances of the stars ? What results ? 
 What necessary in estimating the distances of the stars ? What measure taken ? De 
 scribe the process of determining the distance of the stars by parallax. 279. Wha 
 ib the parallax of the stars found to be, and what follows as a consequence ? What 
 
,5H ASTRONOMY. 
 
 our sun, with its whole retinue of planetary worlds, would occupy 
 a space scarcely exceeding the thickness of a spider's web.* 
 
 If the nearest of the fixed stars are placed at such inconceivable distances in tho 
 regions of space, with what line shall we measure the distance of those which are a thou- 
 eand or a million of times as much farther from them, as these are from us ? 
 
 280. If the annual parallax of a star were accurately known, 
 it would be easy to compute its distance by the following rule : 
 
 As the sine of the star's parallax : 
 
 Is to radius, or ninety degrees : : 
 
 So is the earth's distance from the sun : 
 
 To the star's distance from the sun. 
 
 If we allow the annual parallax of the nearest star to be 1", 
 the calculation will be, 
 As 0.0000048481368=Nat. Sine of 1". 
 Is to 1.0000000000000=Nat. Sine of 90. 
 So is 95, 273,868. 867748554=Earth's distance from the sun 
 To 19,651,627, 683,449=Star's distance from the sun. 
 
 In this calculation we have supposed the earth to be placed at the mean distance of 
 34,047 of its own semi-diameters, or 95,273,868.867748554 miles from the sun, which makes 
 the star's distance a very little less than twenty billions of miles. Dr. Herschel says 
 i hat Sirius cannot be nearer than 100,000 times the diameter of the earth's orbit, or 
 19,007,788,800,000 of miles. 
 
 Biot, who either takes the earth's distance greater than he lays it down in his Traite 
 Elementaire d'Astronomie Physique, or has made an error in figures, makes the dis- 
 tance 20,086,868,036,404. Dr. Brewster makes it 20,159,665,000,000 miles. A mean of 
 these computations, is 20 billions ; that is, 20 millions of millions of miles to a parallax 
 of 1'. 
 
 Astronomers are generally agreed in the opinion that the annual parallax of the stars 
 is less than 1", and consequently that the nearest of them is placed at a much greater 
 distance from us, than these calculations make it. It was, however, announced in 1832, 
 that M. d'Assas, a French astronomer, had satisfactorily established the annual parallax 
 of Keid (a small star 8 N. of Gamma Eridani), to be 2', that of Rigel, in Orion, to be 
 1".43, and that of Sirius to be 1".24. If these results could be relied on, Keid would be 
 but 10 billions, Rigel but 14 billions, and Sirius 16 billions of miles from the earth. Ttiis 
 latter distance is, however, so great that, if Sirius were to fall toward the earth at 
 the rate of a million of miles a day, it would take it forty-three thousand, three hundred 
 years to reach the earth ; or, if the Almighty were now to blot it out of the heavens, its 
 brilliance wpuld continue undiminished in our hemisphere for the space of three years 
 to come. 
 
 * A just idea of the import of this term, will impart a force and sublimity to an expres- 
 sion of St. James, which no power of words could improve. It is said, chapter i. verse 
 17, of Him from whom cometh down every good and perfect gift, that there is " QVK Vt 
 7i apa/l/lay?/ TJ Tpoirqs airoaKiaafxa." Literally, there is "neither parallax nor 
 s/uidow of change :" As if the apostle had said Peradventure, that in traveling millions 
 and millions of miles through the regions of immensity, there may be a sensible parallax 
 to some of the fixed stars ; yet, as to the Father of Lights, view him from whatever point 
 of his empire we may, he is without parallax or shadow of change I 
 
 then, of the mo distant stars? 280. How deduce the distance of a star from its 
 parallax, if known > Computation laid down ? Dr. Herschel's remark? Riot's estimate? 
 Dr. Brewster's? The mean of these three estimates ? Are astronomers agreed as to thy 
 i.;rjvliax of the stars? .M. d'Assas' computation* :unl n-sults? 
 
NUMBER, DISTANCE, AJND ECONOMY OF THE STARS. 16} 
 
 281. The most brilliant stars, till recently, were supposed to 
 be situated nearest the earth, but later observations prove that, 
 this opinion is not well founded, since some of the smaller stars 
 appear to have not only a greater annual parallax, but an 
 absolute motion in space, much greater than those of the bright- 
 est class. 
 
 282. It has been computed that the light of Sirius, although 
 twenty thousand million times less than that of our sun, is never- 
 theless three hundred and twenty-four times greater than that of 
 a star of the 6th magnitude. If we suppose the two stars to 
 be really of the same size, it is easy to show that the star of the 
 sixth magnitude is fifty-seven and one-third times farther from us 
 than Sirius is, because light diminishes as the square of the dis- 
 tance of the luminous body increases. 
 
 By the same reasoning it may be shown, that if Sirius were placed where the sun is, t 
 would appear to us to be four times as large as the sun, and give four times as much light 
 and heat. It is by no means unreasonable to suppose, that many of the fixed starb 
 exceed a million of miles in diameter. 
 
 283. We may pretty safely affirm, then, that stars of the 
 sixth magnitude are not less than nine hundred millions of millions 
 of miles distant from us ; or a million of times farther from us than 
 the planet Saturn, which is scarcely visible to the naked eye. 
 But the human mind in its present state can no more appreciate 
 such distances than it can infinity ; for if our earth, which moves 
 at more than the inconceivable velocity of a million and a half 
 of miles a day, were to be hurried from its orbit, and to take the 
 same rapid flight over this immense tract, it would not traverse 
 it in sixteen hundred thousand years ; and every ray of light, 
 although it moves at the rate of one hundred and ninety-three 
 thousand miles in a single second of time, is more than one hun- 
 dred and seventy years in coming from the star to us. 
 
 But what is even this, compared with that measureless extent which the discoveries of 
 the telescope indicate? According to Dr. Herschel, the light of some of the nebulae, jusl 
 perceptible through his 40 feet telescope, must have been a million of ages in coming tj 
 the earth ; and should any of them be now destroyed, they would continue to be percep- 
 tible for a trillion of ages to come. 
 
 Dr. Hersrhel informs us, that the glass which he used would separate stars at 497 times 
 the distance of Sirius. 
 
 284. It is one of the wonders of creation, that any phenomena 
 of bodies at such an immense distance from us should be percep- 
 tible by human sight ; but it is a part of the Divine Maker's 
 
 281. Former supposed relative distance of the most brilliant stars ? Present opinion, 
 und on what founded? 282. What computation as to the light of Sirius? What con- 
 clusion as to the distance of other stars ? How, then, would he appear if as near as ou : 
 hun? What conclusion as to the magnitude of the stars? 283. Distance of the sixth 
 magnitude stars ? How measured by the flight of the earth ? Of light? What further 
 estimate by Dr. Herschel ? 284. What remark respecting our knowledge of the start 
 
> 52 ASTRONOMY. 
 
 plan, that although they do not act physically upon us, yet t l iey 
 should so far be objects of our perception, as to expand our ideas 
 of the vastness of the universe, and of the stupendous extent 
 and operations of his omnipotence. 
 
 " With these facts before us," says an eminent astronomer and divine, " it is most rea- 
 sonable to conclude, that those expressions in the Mosaic history of Creation, which 
 relate to the creation of the fixed stars, are not to be understood as referring to the time 
 when they were brought into existence, as if they had been created about the same time 
 with our earth ; but as simply declaring the fact, that, at whatever period in duration 
 they were created, they derived their e&istenee from, God." 
 
 285. "That the stars here mentioned" (Gen. i. 16), says a 
 distinguished commentator, "were the planets of our system, 
 and not the fixed stars, seems a just inference from the fact, that 
 after mentioning them, Moses immediately subjoins, * And 
 Elohim set them in the firmament of the heaven to give light 
 upon the earth, and to rule over the day and over the night ;' 
 evidently alluding to Yenus and Jupiter, which are alternately 
 our morning and evening stars, and which ' give light upon the 
 earth/ far surpassing in brilliancy any of the fixed stars." 
 
 However vast the universe now appears, however numerous the worlds which may 
 exist within its boundless range, the language of Scripture, and Scripture alone, is suffi- 
 ciently comprehensive and sublime to express all the emotions which naturally arise in 
 the mind when contemplating its structure. This shows not only the harmony which 
 subsists between the discoveries of the Revelation and the discoveries of Science, but 
 also forms, by itself, a strong presumptive evidence, that the records of the Bible arc 
 authentic and divine. 
 
 286. We have hitherto described the stars as being immov- 
 able and at rest ; but from a series of observations on double 
 stars, Dr. Herschel found that a great many of them have 
 changed their situations with regard to each other ; that some 
 perform revolutions about others, at known and regular periods, 
 and that the motion of some is direct, while that of others is 
 retrograde ; and that many of them have dark spots upon their 
 surface, and turn on their axes, like the sun. 
 
 287. A remarkable change appears to be gradually taking 
 place in the relative distances of the stars from each other in 
 the constellation Hercules. The stars in this region appear to 
 be spreading farther and farther apart, while those in the oppo- 
 site point of the heavens seem to close nearer and nearer together, 
 in the same manner as when walking through a forest, the treei 
 toward which we advance appear to be constantly separating 
 while the distance between those which we leave behind is grr 
 dually contracting. 
 
 by sight? How -vrc we to understand Moses as to the time of the creation of the stars? 
 285. What meant by the "stars" mentioned Gen. i., 16? What proof? Remark respit- 
 ing the Scriptures ? 286. How have the stars been described hitherto? What ia the. 
 tact? 287. What example cited ? What astonishing conclusion ? 
 
NUMBER, DISTANCE, AND ECONOMY OF THE STARS. 153 
 
 From this appearance it is concluded, that the sun, with all its retinue of planetary 
 worlds, is moving through the regions of the universe, toward some distant center, or 
 nround some wide circumference at the rate of near thirty thousand miles an hour ; and 
 that it is therefore highly probable, if not absolutely certain, that we shall never occupy 
 that portion of absolute space, through which we are at this moment passing, during 
 all the succeeding ages of eternity. 
 
 288. The direction of the Sun's motion is towards the constel- 
 lation of Hercules ; R. A. 259 ; Dec. 35. This velocity 
 in space is estimated at 8 miles per second, or 28,000 miles 
 per hour. His period is about 18,200,000 years ; and the 
 arc of his orbit, over which he has traveled since the creation 
 of the world, amounts to only about 3- oVo-th P art of his orbit, or 
 about t minutes an arc so small, compared with the whole, as 
 to be hardly distinguishable from a straight line. 
 
 With this wonderful fact in view, we may no longer consider the sun as fixed and sta- 
 tionary, but rather as a vast and luminous planet, sustaining the same relation to some 
 central orb that the primary planets sustain to him, or that the secondaries sustain to 
 their primaries. Nor is it necessary that the stupendous mechanism of nature should be 
 restricted even to these sublime proportions. The sun's central body may also have its 
 orbit, and its center of attraction and motion, and so on, till, as Dr. Dick observes, we 
 come to the great center of all to the THRONE OF GOD ! 
 
 Professor Madler, of Dorpat, in Russia, has recently announced as a discovery that 
 the star Alcyone, one of the seven stars, is the center around which the sun and solar 
 Bystem are revolving. 
 
 289. Dr. Dick, the author of the CHRISTIAN PHILOSOPHER, 
 endeavors to convey some idea of the boundless extent of the 
 universe, by the following sublime illustration : 
 
 "Suppose that one of the highest order of intelligences is 
 endowed with a power of rapid motion superior to that of light, 
 and with a corresponding degree of intellectual energy ; that he 
 has been flying without intermission, from one province of crea- 
 tion to another, for six thousand years, and will continue the 
 same rapid course for a thousand million years to come, it is 
 highly probable, if not absolutely certain, that, at the end of this 
 vast tour, he would have advanced no farther than the ' sub- 
 urbs of creation/ and that all the magnificent systems of mate- 
 rial and intellectual beings he had surveyed, during his rapid 
 flight, and for such a length of ages, bear no more proportion to 
 the whole empire of Omnipotence, than the smallest grain of 
 sand does to all the particles of matter contained in ten thousand 
 worlds." 
 
 Were a seraph, in prosecuting the tour of creation in the manner now stated, ever to 
 arrive at a limit beyond which no farther displays of the Divinity could be perceived, the 
 thought would overwhelm his faculties with unutterable emotions ; he would feel that he 
 had now, in some measure, comprehended all the plans and operations of Omnipotence, 
 and that no farther manifestation of the Divine glory remained to be explored. But we 
 may rest assured that this can never happen in the case of any created intelligence. 
 
 288 The direction and velocity of the sun ? Period? Arc of orbit passed over sincj 
 creation? How, then, should we consider the sun? View of the universe ? Discovery 
 of Professor Madler ? 289. Dr. Dick's illustrations ? 
 
154 ASTRONOMY. 
 
 290. There is, moreover, an argument derivable from the 
 laws of the physical world, that seems to strengthen, I had 
 almost said, to confirm, this idea of the Infinity of the material 
 universe. It is this If the number of stars be finite, and 
 occupy only a part of space, the outward stars would be con- 
 tinually attracted to those within, and in time would unite in 
 one. But if the number be infinite, and they occupy an infinite 
 space, all parts would be nearly in equilibrio, and consequently 
 each fixed star, being equally attracted in every direction, would 
 keep its place. 
 
 No wonder, then, that the Psalmist was so affected with the idea of the immensity of 
 the universe, that he seems almost afraid lest he should be overlooked amidst the immen- 
 sity of beings that must needs be under the superintendence of God ; nor that any finite 
 mortal should exclaim, when contemplating the heavens " What is man, that THOU 
 art mindful of him4" 
 
 CHAPTER XVII. 
 
 FALLING, OR SHOOTING STARS, 
 
 291. THE phenomenon of shooting stars, as it is called, is com- 
 mon to all parts of the earth ; but is most frequently seen in 
 tropical regions. The unerring aim, the startling velocity, and 
 vivid brightness with which they seem to dart athwart the sky, 
 and as suddenly expire, excite our admiration ; and we often 
 ask, " What can they be ?" 
 
 But frequent as they are, this interesting phenomenon is not 
 well understood. Some imagine that they are occasioned,. by 
 electricity, and others, that they are nothing but luminous gas. 
 Others again have supposed, that some of them are luminous 
 bodies which accompany the earth in its revolution around the 
 Bun, and that their return to certain places might be calculated 
 with as much certainty and exactness as that of any of the 
 comets. 
 
 292. Dr. Burney, of Gosport, kept a record of all that he 
 observed in the course of several years. The number which he. 
 noticed in 1819 was 121, and in 1820 he saw 131. Professor 
 
 290. What argument supposed to favor the idea of a boundless universe? Allusion tc 
 the Psalmist? 291. Where are shooting stars most common? Are they well under 
 stood ? What theories stated ? 292> r T)r. Burney's record? Professor Green's opinion? 
 Signior Baccaria's opinion, and his reasons for it? 
 
FALLING OR SHOOTING STARS 150 
 
 Green is confident that a much larger number are annually seen 
 in the United States. 
 
 Signior Baccaria supposed they were occasioned by electricity, 
 and thinks this opinion is confirmed by the following observa- 
 tions. About an hour after sunset, he and some friends, that 
 were with him, observed a falling star directing its course directly 
 toward them, and apparently growing larger and larger, but just 
 before it reached them it disappeared. On vanishing, their 
 faces, hands, and clothes, with the earth and all the neighboring 
 objects, became suddenly illuminated with a diffused and lambent 
 light. It was attended with no noise. During their surprise at 
 this appearance, a servant informed them that he had seen a 
 light shine suddenly in the garden, and especially upon the 
 streams which he was throwing to water it. 
 
 The Signior also observed a quantity of electric matter collect about his kite, which 
 had very much the appearance of a falling star. Sometimes he saw a kind of hale 
 accompanying the kite, as it changed its place, leaving some glimmering of light in tho 
 place it had quitted. 
 
 293. Shooting stars have been supposed by those meteorolo- 
 gists who refer them to electricity or luminous gas, to prognos- 
 ticate changes in the weather, such as rain, wind, &c. ; and there 
 is, perhaps, some truth in this opinion. The duration of the 
 brilliant track which they leave behind them, in their motion 
 through the air, will probably be found to be longer or shorter, 
 according as watery vapor abounds in the atmosphere. 
 
 The notion that this phenomenon betokens high winds, is of great antiquity. Virgil, 
 in the first book of his Georgics, expresses the same idea : 
 
 " Saepe etiam Stellas vento impendente videbis 
 Praecipites ccelo labi ; noctisque per umbram 
 Flammarum longos a tergo albescere tractus." 
 
 " And oft, before tempestuous winds arise, 
 The seeming stars fall headlong from the skies, 
 And shooting through the darkness, gild the night 
 With sweeping glories and long trails of light." 
 
 294. The number of shooting stars observed in a single night, 
 though variable, is commonly very small. There are, however, 
 several instances on record of their falling in " showers " when 
 every star in the firmament seems loosened from its sphere, and 
 moving in lawless flight from one end of the heavens to the 
 other. 
 
 As early as the year 472, in the month of November, a phe- 
 nomenon of this kind took place near Constantinople. As Theo- 
 
 293. What are they supposed by some to prognosticate ? What other ancient notion ? 
 Poetic quotation? 294. What said of then-umber of shooting stars? What instance 1 ) 
 jf "meteoric showers" cited? 
 
15O ASTRONOMY. 
 
 phanes relates, " the sky appeared to be on fire," with the corm* 
 cations of the flying meteors. 
 
 A shower of stars exactly similar took place in Canada, between the 3d and 4th of 
 July, 1814, and another at Montreal, in November, 1819. In all these cases, a residuum, 
 or black dust, was deposited upon the surface of the waters, and upon the roofs of build- 
 ings, and other objects. In the year 1810, " inflamed substances," it is said, fell into, 
 and around lake Van, in Armenia, which stained the water of a blood color, and cleft 
 the earth in various places. On the 5th of September, 1819, a like phenomenon was seen 
 in Moravia. History furnishes many more instances of meteoric showers, depositing a 
 red dust in some places, so plentiful as to admit of chemical analysis. 
 
 295. The commissioner (Mr. Andrew Ellicott), who was sent 
 out by our government to fix the boundary between the Spanish 
 possessions in North America and the United States, witnessed 
 a -very extraordinary flight of shooting stars, which filled the 
 whole atmosphere from Cape Florida to the West India Islands. 
 This grand phenomenon took place the 12th of November, 1799, 
 and is thus described : " I was called up," says Mr. Ellicott, 
 " about 3 o'clock in the morning, to see the shooting stars, as 
 they are called. The phenomenon was grand and awful. The 
 whole heavens appeared as if illuminated with sky-rockets, 
 which disappeared only by the light of the sun, after daybreak. 
 The meteors, which at any one instant of time appeared as 
 numerous as the stars, flew in all possible directions except from 
 the earth, toward which they all inclined more or less, and some 
 of them descended perpendicularly over the vessel we were in, so 
 that I was in constant expectation of their falling on us." 
 
 Mr. Ellicott further states that his thermometer, which had been at 80 Fahr. for the four 
 days preceding, fell to 56 about 4 o'clock, A. M., and that nearly at the same time, the 
 wind changed from the south to the northwest, from whence it blew with great violence 
 for three days without intermission. 
 
 These same appearances were observed the same night at Santa Pe de Bogota, Cu- 
 mana, Quito, and Peru, in South America ; and as far north as Labrador and Greenland, 
 extending to Weimar in Germany, being thus visible over an extent on the globe of 64* 
 of latitude, and 94 of longitude. 
 
 The celebrated Humboldt, accompanied by M. Bompland, 
 then in S. America, thus speaks of the phenomenon : " Toward 
 the morning of the 13th of November, 1799, we witnessed a 
 most extraordinary scene of shooting meteors. Thousands of 
 bolides, and falling stars succeeded each other during four hours. 
 Their direction was very regular from north to south. From 
 the beginning of the phenomenon there was not a space in the 
 firmament, equal in extent to three diameters of the moon, 
 which was not filled every instant with bolides or falling stars. 
 All the meteors left luminous traces, or phosphorescent bands 
 behind them, which lasted seven or eight seconds." 
 
 295. What phenomenon described by Mr. Ellicott ? When and where ? EtiVf on hie 
 thermometer ? Where else observed, and by whom? 
 
FALLING OR SHOOTING STARS 157 
 
 Thy phenomenon was witnessed by the Capuchin missionary at San Fernando do 
 Afiur*, a village situated in lat. 7 53' 12", amidst the savannahs of the province of 
 Varinas; by the Franciscan monks stationed near the cataracts of the Oronoco, and at 
 Marca, on the banks of the Rio Negro, lat. 2 40", long. 70 21', and in the west of Bra2.il, 
 as far as the equator itself; and also at the city of Porto Cabello, lat. 10 6' 52", in French 
 Guiana, Popayan, Quito, and Peru. It is somewhat surprising that the same appearances, 
 )bderved in places so widely separated, amid the vast and lonely deserts of South 
 Vmerica, should have been seen, the same night, in the Ijnited States, in Labrador, in 
 Greenland, and at Itterstadt, near Weimar, in Germany ! 
 
 296. We are told that thirty years before, at the city of 
 Quito, "there was seen in one part of the sky, above the volcano 
 of Cayamburo, so great a number of falling stars, that the moun- 
 tain was thought to be in flames. This singular sight lasted 
 more than an hour. The people assembled in the plain of Exida, 
 where a nmgnificent view presents itself of the highest summits 
 of the Cordilleras. A procession was already on the point of 
 setting out from the convent of St. Francis, when it was per 
 ceived that the blaze on the horizon was caused by fiery meteors, 
 which ran along the sky in all directions, at the altitude of 12 
 or 13 degrees." 
 
 297. But the most sublime phenomenon of shooting stars, of 
 which the world has furnished any record, was witnessed through- 
 out the United States on the morning of the 13th of November, 
 1833. The entire extent of this astonishing exhibition has not 
 been precisely ascertained, but it covered no inconsiderable por- 
 tion of the earth's surface. It has been traced from the longi- 
 tude of 61, in the Atlantic ocean, to longitude 100 in Central 
 Mexico, and from the North American lakes to the West Indies. 
 It was not seen, however, anywhere in Europe, nor in South 
 America, nor in any part of the Pacific Ocean yet heard from. 
 
 Everywhere, within the limits above mentioned, the first 
 appearance was that of fireworks of the most imposing grandeur, 
 covering the entire vault of heaven with myriads of fire-balls, 
 resembling sky-rockets/ Their coruscations were bright, gleam- 
 ing and incessant, and they fell thick as the flakes in the early 
 snows of December. (See cut on the next page.) 
 
 To the splendors of this celestial exhibition, the most brilliant sky-rockets and fire- 
 works of art bear less relation than the twinkling of the most tiny star to the broad 
 glare of the sun. The whole heavens seemed in motion, and suggested to some the awful 
 grandeur of the image employed in the apocalypse, upon the opening of the sixth seal, 
 when " the stars of heaven fell unto the earth, even as a fig-tree casteth her untimely 
 figs, when she is shaken of a mighty wind." 
 
 298. One of the most remarkable circumstances attending 
 his display was, that the meteors all seemed to emanate from 
 
 296. What other similar phenomenon cited ? 297. What still more sublime spectacle/ 
 to extent? Its appearance ? 
 
Ib8 
 
 ASTRONOMY. 
 
 one and the same point, a little southeast of the zenith. Follow- 
 ing the arch of the sky, they ran along with immense velocity, 
 describing, in some instances, an arc of 30 or 40 in a few 
 
 METEORIC SHOWBK OF NOVEMBER, 1S33. 
 
 seconds. On more attentive inspection it was seen, that the 
 meteors exhibited three distinct varieties ; the first, consisting 
 of phosphoric lines, apparently described by a point ; the second, 
 of large fire-balls, that at intervals darted along the sky, leaving 
 luminous trains, which occasionally remained in view for a num- 
 ber of minutes, and, in some cases, for half an hour or more ; 
 the third, of undefined luminous bodies, which remained nearly 
 stationary in the heavens for a long time. 
 
 Those of the first variety were the most numerous, and resembled a shower of fiery 
 snow driven with inconceivable velocity to the north of west. The second kind appeared 
 more \\kefalling stars a spectacle which was contemplated by the more unenlightened 
 beholders with great amazement and terror. The trains which they left were commonly 
 white, but sometimes were tinged with various prismatic colors, of great beauty. 
 
 299. These fire-balls were occasionally of enormous size. Dr. 
 Smith, of North Carolina, describes one which appeared larger 
 than the full moon rising. " I was," says he, " startled by the 
 
 298 What remarkable circumstance attended this phenomenon? Variety of meteors? 
 209. What said of the fireballs seen? Of their size? 
 
FALLING OR SHOOTING STARS. 
 
 159 
 
 A LARGK METEOR. 
 
 splendid light in which the surrounding scene was exhibited, ren- 
 dering even small objects quite visible." 
 
 The same ball, or a similar one, 
 seen at New Haven, passed off in a 
 northwest direction, and exploded a 
 little northward of the star Capella, 
 leaving, just behind the place of 
 explosion, a train of peculiar beauty. 
 The line of direction was at first 
 nearly straight ; but it soon began to 
 contract in length, to dilate in breadth, 
 and to assume the figure of a serpent 
 SCROLLING itself up, until it appeared 
 like a luminous cloud of vapor, float- 
 ing gracefully in the air, where it 
 remained ia full view for several 
 minutes. 
 
 If this body were at the distance of 
 110 miles from the observer, it must 
 have had a diameter of one mile ; if 
 at the distance of 11 miles, its diame- 
 ter was 528 feet ; and if only one mile 
 
 off, it must have been 48 feet in diameter. These tonsiderations leave no doubt that 
 many of the meteors were bodies of large size. 
 
 300. Of the third variety of meteors, the following are remark- 
 able examples : At Poland, Ohio, a luminous body was dis- 
 tinctly visible in the northeast for more than an hour. It was 
 very brilliant, in the form of a pruning-hook, and apparently 
 twenty feet long, and eighteen inches broad. It gradually 
 settled toward the horizon, until it disappeared. 
 
 At Niagara Falls, a large luminous body, shaped like a square table, was seen near 
 the zenith, remaining for some time almost stationary, emitting large streams of light. 
 
 301. The point from which the meteors seemed to emanate, 
 was observed, by those who fixed its position among the stars, 
 to be in constellation Leo ; and, according to their concurrent 
 testimony, this RADIANT POINT was stationary among the stars, 
 during the whole period of observation ; that is, it did not move 
 along with the earth, in its diurnal revolution eastward, but 
 accompanied the stars in their apparent progress westward. 
 
 A remarkable change ofweatfier, from warm to cold, accompanied the meteoric 
 shower, or immediately followed it. In all parts of the United States, this change was 
 remarkable for its suddenness and intensity. In many places, the day preceding had 
 been unusually warm for the season, but, before the next morning, a severe frost ensued, 
 unparalleled for the tune of year. 
 
 302. In attempting to explain these mysterious phenomena, it 
 is argued, in the first place, that the meteors had their origin 
 beyond the limits of our atmosphere ; that they of course did not 
 belong to this earth, but to the regions of space exterior to it 
 
 800. What other variety of meteors described ? Where ? 801. Point from which 
 .hey seemed to emanate ? What change of weather follc red ? 802. What fact asserted 
 firf to the dwtanoe from which those meteors came Professor Olmsted's estimate ot 
 dibt ince ? 
 
i60 ASTRONOMY. 
 
 The reason on which the conclusion is founded is this : All bodies near the eartL 
 including the atmosphere itself, have a common motion with the earth around its axis 
 from west to east; but the radiant point, that indicated the source from which the 
 meteors emanated, followed the course of the stars from east to west ; therefore, it was 
 Independent of the earth's rotation, and consequently, at a great distance from it, ana 
 beyond the limits of the atmosphere. The height of the meteoric cloud, or radiant point, 
 above the earth's surface, was, according to the mean average of Professor Ounsted'a 
 observations, not less than 2238 miles. 
 
 303. That the meteorsVere constituted of very light, combus- 
 tible materials, seems to be evident, from their exhibiting the 
 actual phenomena of combustion, they being consumed, or con- 
 verted into smoke, with- intense light ; and the extreme tenuity 
 of the substance composing them is inferred from the fact that 
 they were stopped by the resistance of the air. Had their quan- 
 tity of matter been considerable, with so prodigious a velocity, 
 they would have had sufficient momentum to dash them upon 
 the earth ; where the most disastrous consequences might have 
 followed. 
 
 The momentum of even light bodies of such size, and in such numbers, traversing the 
 atmosphere with such astonishing velocity, must have produced extensive derangements 
 in the atmospheric equilibrium. Cold air from the upper regions would be brought down 
 to the earth; the portions of air incumbent over districts of country remote from each 
 other, being mutually displaced, would exchange places, the air of the warm latitudes be 
 transferred to colder, and that of cold latitudes to warmer regions. 
 
 304. Various hypotheses have been proposed to account for this 
 wonderful phenomena. The agent which most readily suggests 
 itself in this, and in many other unexplained natural appearances, 
 is electricity. But no known properties of electricity are adequate 
 to account for the production of the meteors, for their motions, or 
 for the trains which they, in many instances, left behind them. 
 Others, again, have referred their proximate cause to magnetism. 
 and to phosphureted hydrogen ; both of which, however, seem to 
 be utterly insufficient, so far as their properties are known, to 
 account for so unusual a phenomenon. 
 
 305. Professor Olmsted, of Yale College, who has taken much 
 pains to collect facts, and to establish a permanent theory for 
 the periodical recurrence of such phenomena, came to the con- 
 clusion, that 
 
 The meteors of November 13th, 1833, emanated from a nebulous 
 body, which was then pursuing its way along with the earth around 
 the sun ; that this body continues to revolve around the, sun, in an 
 elliptical orbit but little inclined to the plane of the ecliptic, ana 
 having its aphelion near the orbit of the earth ; and finally, thai 
 
 803. Supposed composition of these meteors? Why? 804. Hypotheses for explain* 
 f ng phenomenon? Are they satisfactory? 805. Professor Olmsted's conclusion; 
 
FALLING OR SHOOTING STARS. 161 
 
 tJie, body has a period of nearly six months, and that its perihelion 
 is a Hi tie below the orbit of Mercury.* 
 
 This theory at least accommodates itself to the remarkable fact, that almost all the 
 phenomena of this description, which are known to have happened, have occurred in the 
 two opposite months of April and November. A similar exhibition of meteors to that of 
 November, 1833, was observed on the same day of the week, April 20th, 1803, at Kich- 
 mond, Virginia ; Stockbridge, Massachusetts ; and at Halifax, in British America. Another 
 WAS witnessed in the autumn of 1818, in the North Sea, when, in the language of the 
 observers, " all the surrounding atmosphere was enveloped in one expansive sea of fire, 
 exhibiting the appearance of another Moscow, in flames." 
 
 * After the first edition of this work went to press, the author was politely fur- 
 nished, by Professor Olmsted, with the following communication. 
 
 " I am happy to hear that you propose to stereotype your ' Geography of the Heavens, 
 it has done much, I believe, to diffuse a popular knowledge of astronomy, and I am pleased 
 that your efforts are rewarded by an extended patronage. 
 
 "Were I now to express my views on the subject (Meteoric /Showers) in as condensed 
 a form as possible, I should state there, in some such terms as the following : The meteoric 
 showers which have occurred for several years past on or about the 13th of November v 
 are characterized by four peculiarities, which distinguish them from ordinary shooting 
 stars. First, they are far more numerous than common, and are larger and brighter. 
 Secondly, they are in much greater proportion than usual, accompanied by luminous 
 trains. Thirdly, thsy mostly appear to radiate from a common center ; that is, were 
 their paths in the heavens traced backward, they would meet in the same part of the 
 heavens : this point has for three years past, at least, been situated in the constellation 
 Leo. Fourthly, the greatest display is everywhere at nearly the same time of night, 
 namely, from three to four o'clock a time about half-way from midnight to sunrise. The 
 meteors are inferred to consist of combustible matter, because they are seen to take firo 
 and burn in the atmosphere. They are known to be very light, because, although they 
 fall toward the earth with immense velocity, few, if any, ever reach the earth, but are 
 arrested by the air, like a wad fired from a piece of artillery. Some of them are inferred 
 to be bodies of comparatively great size, amounting in diameter to several hundred feet, 
 at least, because they are seen under so large an angle, while they are at a great distance 
 from the spectator. Innumerable small bodies, thus consisting of extremely light, thin, 
 combustible matter, existing together in space far beyond the limits of the atmosphere, 
 are believed to compose a body of immense extent, which has been called ' the nebulous 
 body.' Only the skirts or extreme portions of this are brought down to the earth, while 
 the entire extent occupies many thousands, and perhaps several millions of miles. This 
 nebulous body is inferred to have a revolution around the sun, as well as the earth, and 
 to come very near to the latter about the 13th of November each year. This annual 
 meeting every year, for several years in succession, could not take place unless the 
 periodic, time of the nebulous body is either nearly a year, or half a year. Various rea- 
 sons have induced the belief that half a year is the true period ; but this point is con- 
 sidered somewhat doubtful. The zodiacal light, a faint light that appears at different 
 seasons of the year, either immediately preceding the morning or following the evening 
 twi!:j;ht, ascending from the sun in a triangular form, is, with some degree of probability, 
 tho jght to be the nebular body itself, although the existence of such a body, revolving 
 in the solar system, was inferred to be the cause of the meteoric showt-s, before any 
 connection of it with the zodiacal light was even thought of." 
 
 W?tti what remarkable fact docs uis theory accord ? Substance of letter from Professor 
 Olmsted? 
 
162 ASTRONOMY. 
 
 306. Exactly one year previous to the great phenomenon of 
 1833, namely, on the 12th of November, 1832, a similar moteoric 
 display was seen near Mocha, on the Red Sea, by Capt. Ham- 
 mond and crew of the ship Restitution. 
 
 A gentleman in South Carolina thus describes the effect of the phenomenon of 1833, 
 ipon his ignorant blacks : " I was suddenly awakened by the most distressing cries tha^ 
 ever fell on my ears. Shrieks of horror, and cries of mercy, I could hear from most or 
 the negroes of three plantations, amounting in all to about six or eight hundred. While 
 earnestly listening for the cause, I heard a faint noise near the door calling my name ; 
 I arose, and taking my sword, stood at the door. At this moment, I heard the same 
 voice still beseeching me to rise, and saying, '0, my God, the world is on fire !' I then 
 opened the door, and it is difficult to say which excited me most the awfulness of the 
 scene, or the distressed cries of the negroes ; upward of one hundred lay prostrate on the 
 ground some speechless, and some with the bitterest cries, but most with their hands 
 raised, imploring God to save the world and them. The scene was truly awful ; foi 
 never did rain fall much thicker, than the meteora fell toward the earth ; east, wist, 
 north, and south, it was the same !" 
 
 806. What similar meteoric shower referred to ? Description of that of November 
 1333, and its effects upon certain persons ? 
 
PART II. 
 THE SOLAR SYSTEM 
 
 CHAPTER I. 
 
 GENERAL PHENOMENA OF THE SOLAR SYSTEM, 
 HISTORY, &o. 
 
 307. OUR attention has hitherto been directed to those bodies 
 which we see scattered everywhere throughout the whole celes- 
 tial concave. These bodies, as has been shown, twinkle with a 
 reddish and variable light, and appear to have always the same 
 position with regard to each other. We know that their num- 
 ber is very great, and that their distance from us is immeasur- 
 able. 
 
 We are also acquainted with their comparative brightness, and their situation. In a 
 word, we have before us their few visible appearances, to which our knowledge of them 
 is well-nigh limited ; almost all our reasonings in regard to them being founded on con^ 
 parattvely few and uncertain analogies. Accordingly, our chief business thus far has 
 been to detail their number, to describe their brightness and positions, and to give the 
 name? by which they have been designated. 
 
 308. There now remain to be considered certain other celes- 
 tial bodies, all of which, from their remarkable appearance and 
 changes, and some of them from their intimate connection witli 
 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 Uinits 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 with regard to the Earth ; and the MOON, so conspicu- 
 ous among the bodies which give light by night, and from her 
 
 807. Subject of Part II.? Of our investigations hitherto? How distinguished ? IheJi 
 number, distance, &c. ? What has been our chief business thus far? 308. What o<nv 
 remains to be considered? How situated? Which the most important of them? 
 
1 64 ASTRONOMY. 
 
 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 diminished figure. 
 
 309. 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 most striking astronomical phenomena, and so powerful in 
 their influence upon the beholders, as to fill them with perplexity 
 and fear. 
 
 310. 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 farther and farther 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. 
 
 311. Again ; if the Sun's motions be attentively observed, he 
 will be found to have another motion, opposite to his apparent 
 diurnal motion from east to west. This may be perceived dis- 
 tinctly, if we notice, 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. 
 
 312. 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. 
 
 313. There are also situated within the limits of the Zodia< 
 certain other bodies, which, at first view and on a superficial 
 examination, are scarcely distinguishable from the fixed stars. 
 
 809. ^Vhat said of their obscuration ? 810. Of their motions ? 811. Has the Srn 
 an apparent eastward motion ? 312. What said of the Moon's motions and phase*. ( 
 18. What other bodies and their motions ? What called, and why ? 
 
PHENOMENA OF THE SOLAR SYSTEM. 165 
 
 Bat, 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 changing 
 their position with regard to the earth, each other, and the 
 other heavenly bodies. From their wandering, as it were, ic 
 this manner through the heavens, they were called by the Greeks 
 TTkavrjrai, planets, which signifies wanderers. 
 
 314. There also sometimes appear in the heavens, bodies of a 
 very extraordinary aspect, which continue visible for a considera- 
 ble period, 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 celes- 
 tial sphere. They are distinguished from the planets by a dull 
 and cloudy 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 Kourjrai, wmets, which signifies bearded, or having 
 long hair. 
 
 The causes of these various phenomena must have early constituted 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 differ- 
 ent theories were adopted to account for these celestial appearances. 
 
 315. The Egyptians, Chaldeans, Indians, and Chinese, early 
 possessed many astronomical facts, many observations of impor- 
 tant phenomena, and many rules and methods of astronomical 
 calculation ; and it has been supposed, 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 perfec- 
 tion, and that while the principles and explanations of the phe- 
 
 814. Any other bodies described? How distinguished? What called, and why ? Is it 
 probable that these phenomena were early observed? 315. What said of the Egyptians 
 Uhaldeans, <fec.? Of the Chinese in particular? Of the Indians and Chaldeans'/ 
 
166 ASTRONOMY. 
 
 nomena were lost, the isolated, unconnected facts, rules of calcu- 
 lation, and phenomena themselves, remained. 
 
 Thus, the Chinese, who, it is generally agreed, possess the oldest authentic observa- 
 tions 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 before the flood. By mathe 
 matical calculation, it is ascertained that this conjunction really occurred at that time 
 The first observation of a solar eclipse of which the worhl has any knowledge, was made 
 by the Chinese, 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 tho 
 eclipse, that he caused them to be put to death. The Chinese have, from time imme- 
 morial, considered Solar Eclipses and conjunctions of the planets, as prognostics of 
 importance to the Empire, and they have been predicted as a matter of state policy. 
 
 The astronomical epoch of the Chinese, according to Bailly, commenced with Pohi, 
 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 astrono- 
 my 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 forgotten. The Indians, also, profess to have 
 many celestial observations of a very early date. The Chaldeans have been justly cele- 
 brated in all ages for their astronomical observations. When Alexander took Babylon, 
 his preceptor, Callisthenes, 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. 
 
 316. 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. 
 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 maintained by these phuosophers were, that the Earth wah 
 round, thav it had two motions, a diurnal motion on its axis, and an annual 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, Ac. : that her eclipses wer, 
 caused by the Earth's shadow, that the planets were not designed 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. 
 
 317. When that distinguished school of philosophy was estab- 
 lished at Alexandria, in Egypt, by the munificence of the sove- 
 reigns to whom that portion of Alexander's empire had fallen, 
 astronomy recived a new impulse. It was now, in the second 
 century after Christ, that the first complete system or treatise 
 of astronomy of which we have any knowledge, was formed. 
 All before had been unconnected and incomplete. Ptolemy, 
 with the opinions of all antiquity, and of all the philosophers 
 
 816. Of the Greeks? Who first taught astronomy among them.? Date? Who nxt? 
 State some of their doctrines? 317. What record of this science? What of 
 and his works ? 
 
PHENOMENA OF THE SOLAR SYSTEM. 167 
 
 who had preceded him, spread out before him, composed a work 
 m thirteen books, called the Meya/U; Svvrat;^ , or Great System. 
 
 318. Rejecting the doctrine of Pythagoras, who taught that 
 the Sun was the center of the universe, and that the Earth had 
 a diurnal motion on its axis and an annual motion around the 
 Sun, as contrary to the evidence of the senses, Ptolemy endea- 
 vored 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 supposition, 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 heavenly 
 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." 
 
 319. In explaining the celestial phenomena, however, upon 
 his hypothesis, he met with a difficulty in the apparently station- 
 ary attitude and retrograde 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 deferents, 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 recourse to other expedients, until 
 the system became unwieldy, cumbrous, and complicated. This theory, although astro- 
 nomical observations continued to be made, and some distinguished astronomers appeared 
 fro ai time to time, was the prevailing theory until the middle of the 15th 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 13th century, when contemplating 
 the doctrine of the epicycles, exclaimed, " Were the universe thus constructed, if the 
 Deity had called me to his councils at the creation of the world, I could have given him 
 good advice." He did not, however, mean any impiety or irreverence, except what waa 
 directed against the system of Ptolemy. 
 
 320. About the middle of the 15th century, Copernicus, a 
 native of Thorn in Prussia, conceiving a passionate attachment 
 to the study of astronomy, quitted the profession of medicine, 
 and devoted 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 arrangements 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." 
 
 318. His system of astronomy? What singular idea and reasoning? 819. What 
 difficulty did he meet with, and how explain it? What further difficulty? How long 
 did this theory prevail? What anecdote of the King of Castile? 820. What dis- 
 tinguish"d student of astronomy now arose? His impressions in regard to the Ptoleraaki 
 theory T His own rarlicr cmiviVtinns? What other Un.-orics did he study? 
 
168 ASTRONOMY. 
 
 In the opinions of the Egyptian sages, in those of Pythagcras, Philolaus, Aristarcbus, 1 
 and Nicetas, he recognized his own earliest conviction that the Earth was not the center 
 of the universe. His attention was much occupied with the speculation of Martinua 
 Oapella, who placed the Sun between Mars and the Moon, and made Mercury and Venus 
 revolve round him as a center, and with the system of Appollonius Pergceus who made 
 ill the planets revolve around the Sun, while the Sun and Moon were carried around tho 
 3arth in the center of the universe. 
 
 321. The examination, however, of various hypotheses, by 
 Copernicus, gradually expelled 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. Tho 
 Sun he considered as immovable, in the center of the system, 
 while the Earth revolved around him, between the orbits of 
 Yenus and Mars, and produced by its rotation about its axis all 
 the diurnal phenomena of the celestial sphere. The other planets 
 he considered as revolving about the Sun, in orbits exterior to 
 that of the Earth. ( See. the Relative Distances of the Planets' 
 Orbits, Map I. of the Atlas.) 
 
 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 older of the planets, their orbits, magnitudes, 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." 
 
 322. Soon after the death of Copernicus, arose Tycho Brahe, 
 born at Knudstorp, in Norway, in 1546. Such was the distinc- 
 tion which he had attained as an astronomer, that when, dissa- 
 tisfied 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 2,000 crowns per annum. He added to this 
 sum a pension of 1,000 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 generalizations in astronomy. He, 
 however, rejected the system of Copernicus; 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 so simple as that of 
 Copernicus, and involved the absurdity of making the Sun, planets, &c., revolve around 
 a body comparatively insignificant. 
 
 321. How was Copernicus led to discover the true system of astronomy ? What is that 
 system? Does it account for the stations and retrogradations of the ilanets? 822 
 What distinguished astronomer next arose? What said of his detentioa in Denmark 
 U is observations? His theory 
 
PHENOMENA ?.IE SOLAR SYSTEM. 
 
 323. Near the close of tht 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 supposition 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 thiir motions through their 
 orbits, and the times of their revolutions, were proportioned ; all 
 truths of the greatest importance to the science. 
 
 324. 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 variou forms. 
 
 Many minute stars, not visible to the naked eye, were described 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 dis- 
 coveries served to confirm the Oopernican theory, and to show the absurdity of the 
 hypothesis of Ptolemy. 
 
 325. Although the general arrangement and motions of the 
 planetary bodies, together with the figure of their orbits, had 
 been thus determined, the force of power which carries them 
 around in their orbits, was as yet unknown. The discovery of 
 this was reserved for the illustrious Newton, though even his 
 discovery was in some respects anticipated by Copernicus, 
 Kepler and Hooke* By reflecting on the nature of gravity 
 that power which causes bodies to descend toward 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 t ) suppose that perhaps the same power carried the 
 
 828. What two noted astronomers next arose ? What did Kepler discover ? 824. 
 Galileo and his discoveries? What theory did they serve to establish? 825 Wha', 
 pe-at discovery next made, and by whom! How le-1 to it? Successive atepo? 
 
170 ASTRONOMY. 
 
 primary plants 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 planets, and the planets 
 and comets in their orbits around the Sun. 
 
 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 beauti- 
 fu' simplicity the different phenomena of the Sun, planets, moons, and comets, is, that 
 tbo 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 to each other a certain ascertained relation, and in times related to their dis- 
 tances ; that the moons, or secondaries, Devolve 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 revolutions in their orbits are produced 
 by the mysterious power of attraction. The particular mode in which this system is 
 applied to the explanation of the different phenomena, will be exhibited as we proceed to 
 consider, one by one, the several bodies above mentioned. 
 
 326. These bodies, thus arranged and thus revolving, consti- 
 tute 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 primaries 
 are those that revolve about the Sun, as a center. The seconda- 
 ries are those which revolve about the primaries. There have 
 been discovered to this date (1854), thirty-five primary planets, 
 viz. : Mercury, Venus, the Earth, Mars, Flora, Clio, Vesta, Iris, 
 Metis, Eunomia, Psyche, Thetis, Melpomene, Fortuna, Massilia, 
 Lutetia, Calliope, Thalia, Hebe, Parthenope, Irene, Egeria, 
 AstraBa, Juno, Ceres, Pallas, Hygeia, Jupiter, Saturn, Uranus, 
 Neptune, and four other Asteroids, whose names and places have 
 not yet been determined. Mercury is the nearest to the Sun, 
 and the others follow in the order in which they are named. The 
 seventeen small planets from Flora to Hygeia, inclusive, were dis- 
 covered by means of the telescope, and, because they are very 
 small, compared with the others, are called Asteroids. Neptune, 
 also, is a telescopic planet, though much larger than any of the 
 Asteroids. 
 
 There have been discovered twenty secondaries. Of these, 
 the Earth has one, Jupiter four, Saturn eight, Hersckel six, and 
 Neptune one. All these, except our Moon, as well as the Aste- 
 roids and Neptune, are invisible to the naked eye. 
 
 Map I. of the Atlas, " exhibits a plan of the Solar System," comprising the relative 
 magnitudes of the Sun and Planets ; their comparative distances from the Sun, and from 
 each other; the position of their orbits, with respect to each other; the Earth and the 
 Sun ; together with many other particulars which are explained on the map. There, the 
 
 Describe the Copernican theory? 326. What do the bodies mentioned ceistitutc? 
 How are the planets divided? Describe each? What number of primaries ? Name 
 them in order from the Sun ? Which are the Asteroids ? Which telescopic ? How many 
 ,ecoml;viy planets? How dtetriljiuvd? Arc they visible to the nuked tifcf What rfuij 
 
THE SUN HIS DISTANCE, MAGNITUDE, ETC. 171 
 
 flrft and most prominent object which claims attention, is the representation of the 
 Sun's circumference, with its deep radiations, bounding the upper margin of the map. 
 It is apparent, however, that this segment is hardly one-sixth of the whole circumference 
 of which it is a part. Were the map sufficiently large to admit the entire orb of the Sun, 
 even upon so diminutive a scale as there represented, we should then see the Sun and 
 Planets in their just proportions the diameter of the former being 112 times the diameter 
 of the Earth. 
 
 It was intended, originally, to represent the Earth upon a scale of one inch in diameter 
 and the other bodies in that proportion ; but it was found that it would increase the map 
 to four times its size ; and hence it became necessary to assume a scale of half an inch 
 for the Earth's diameter, which makes that of the Sun 56 inches, and the other bodies, as 
 represented upon the map. 
 
 The relative position of the Planets' orbits is also represented, on a scale as large as 
 the sheet would permit. Their relative distances from the Sun as a center, and from each 
 other, are there shown correctly. But had we wished to enlarge the dimensions of these 
 orbits, so that they would exactly correspond with the scale to which we have drawn tho 
 planets, the map must have been nearly two miles in length. *' Hence," says Sir John 
 Herschel, " the idea that we can convey correct notions on this subject, by drawing circles 
 on paper, is out of the question." 
 
 To illustrate this Let us suppose ourselves standing on an extended plane, or field of 
 ice, and that a globe 4 feet 8 inches in diameter is placed in the center of the plane, to 
 represent the Sun. Having cut out of the map the dark circles representing the planets, 
 we may proceed to arrange them in their respective orbits about the Sun, as follows : 
 
 First, we should take Mercury, about the size of a smill currant, and place it on the 
 circumference of a circle 194 feet from the Sun; this circle would represent the orbit of 
 Mercury, in the proper ratio of its magnitude. Next, we should take Venus, about the 
 size of a rather small cherry, and place it on a circle 862 feet from the Sun, to represent 
 the orbit of Venus. Then would come the Earth, about the size of a cherry, revolving in 
 an orbit 500 feet from the Sun. After the Earth we should place Mars, about the size of 
 a cranberry, on a circle T62 feet from the Sun. Neglecting the Asteroids, some of which 
 would not be larger than a pin's head, we should place Jupiter, hardly equal to a mode- 
 rate-sized melon, on a circle at the distance of half a mile (2601 feet) from the Sun ; 
 Saturn, somewhat less, on a circle nearly a mile (4768 feet) from the Sun ; Herschel, about 
 the size of a peach, on the circumference of a circle nearly 2 miles (9591 feet) from the 
 Sun ; and last of all Neptune, a little larger than Herschel, and on a circle of nearly 3 
 miles (15,366 feet) from the Sun. 
 
 To imitate the motions of the planets in the above-mentioned orbits, Mercury must 
 describe its own diameter in 41 seconds ; Venus, in 4 minutes 14 seconds ; the Earth, in 
 T minutes; Mars, in 4 minutes 48 seconds; Jupiter, in 2 hours 56 minutes; Saturn, in 
 8 hours 13 minutes; Herschel, in 12 hours 16 minutes ; and Neptune, in 23 honrs 25 min. 
 
 Many other interesting subjects are embraced in Map I. ; but they are either explained 
 on the map, or in the following chapters, to which they respectively relate. 
 
 CHAPTER II. 
 
 THE SUN HIS DISTANCE, MAGNITUDE, &c. 
 
 321. THE Sun is a vast globe, in the center of the solar sys- 
 tem, dispensing light and heat to all the planets, and governing 
 all their motions. It is the great parent of vegetable life, giv- 
 ing warmth to the seasons, and color to the landscape. Its rays 
 are the cause of various phenomena on the surface of the earth 
 and in the atmosphere. By their agency, all winds are pro- 
 of Map I.? Its soile? Remark of Dr. Hcrtichel? What illustrations of the 8<>'ar Syatoin 
 does he furnish? 827. Sucjeu cf Chapter II.? Describe- the Sun? 
 
 B.G. b 
 
172 
 
 ASTRONOMY. 
 
 
 duced, aiid the waters of the sea are made to circulate in vapor 
 through the air, aud irrigate the land, producing springs and rivers. 
 328. The Sun is by far the largest of the heavenly bodies 
 whose dimensions have been definitely ascertained. Its diameter 
 is about 889,000 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 SUN AND THE MOON'S ORBIT. 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 conceived to be in the 
 infancy of astronomy. 
 
 The mean distance of the Moon from the 
 Earth is 240,000 miles, consequently the average 
 diameter of her orbit is 480,000 miles ; and yet, 
 were the Sun to take the place of the Earth, he 
 would fill the whole orbit of the Moon, and 
 extend 200,000 miles beyond it in every direc- 
 tion ! To pass from side to side through his 
 center, at railroad speed (30 miles an hour), 
 would require nearly three and a half years , 
 and to traverse his vast circumference nearly eleven years. 
 
 Here let the student refer to Map I., where the Relative Magnitudes of the Sun and 
 Planets are exhibited. Let him compare the segment of the Sun's circumference, aa 
 there represented, with the entire circumference of the Earth. They are both drawn upou 
 the same scale. The segment of the Sun's circumference, since it is almost a straight 
 line, must be a very small part of what the whole circumference would be, were it repre- 
 sented entire. Let the student understand this diagram, and he will be in some measure 
 able to conceive how like a mere point the Earth is, compared with the Sun, and to form 
 in his mind some image of the vast magnitude of the latter. 
 
 V" 329. The next thing which fills the mind with wonder, is the 
 distance at which so great a body must be placed, to occupy, 
 apparently, so small a space in the firmament. The Sun's mean 
 distance from the Earth is twelve thousand times the Earth's 
 diameter, or a little more than 95,000,000 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 200 miles a day, would not traverse it in thirteen hundred 
 years; and, that a cannon ball, flying night and day, at the 
 rate of 16 miles a minute, would not reach it in eleven years. 
 
 330. The Sun, when viewed through a telescope, presents the 
 appearance of an enormous globe of fire, frequently in a state of 
 violent agitation or ebullition ; dark spots of irregular form, 
 
 S'Jb. His magnitude? Diameter? Compared with the Earth ? What illustration given? 
 What reference to the Map? 329. Distance of the Sun? What illustration given 
 4HH How does the Sun appear through a ttJcjcopo? Describe those rpotj? 
 
THE SUN HIS DISTANCE. MAGNITUDE, ETC. 173 
 
 rarely visible to the naked eye, frequently pass over his disc, 
 from east to west, in the period of nearly fourteen days. 
 
 Th*e spots are usually surrounded by a SPOTS on THE SCN. 
 
 penumbra, or less deeply shaded border, 
 and that, by a margin of light more bril- 
 liant that that of the Sun. A spot when 
 first seen on the eastern edge of the Sun, 
 appears like a line which progressively ex- 
 tends in breadth, and increases its appa- 
 rent velocity, till it reaches the middle, 
 when it begins to contract, and to move 
 less rapidiy, till it 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 revo- 
 lutions. But, as a general thing, the spots 
 on the fun are neither permanent nor uni- 
 form. 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. 
 
 331. It is the general opinion, that spots on the Sun were 
 first discovered by Galileo, in the beginning' of the year 1611 ; 
 though Scheiner, Harriot, and Fabricius, observed them about 
 the same time. During a period of 18 years from this time, the 
 Sun was never found entirely clear of spots, excepting a few 
 days in December, 1624 : at other times, there 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 pre- 
 sented an unspotted disc. Since the beginning of the eighteenth 
 century, scarcely a year has passed, in which spots have not 
 been visible, 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 disc, as seen from the Earth, corre- 
 sponds to 462 miles ; and a circle of this diameter (containing therefore nearly 220,000 
 square miles) is the least space which can be distinctly discerned on the Sun as a vitiblt) 
 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 examined the solar 
 spots with considerable minuteness, and have several times seen spots which were not 
 less than the one twenty-fifth part of the Sun's diameter, which would make them about 
 ?2,192 miles in 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 vist 
 ble to the naked eye which we must believe, unless we refuse respectable testimony 
 they could not have been much less than 50,000 miles in diameter." 
 
 83i Who first saw them? When? How was it for the next IS years? How in 1625 '' 
 From 1650tol(5<0? From 1676 to 1684? How since the beginning of the eighteenth 
 sectary? Dr. Herschel's measurements? Dr. Dick's remarks and conclusion ? 
 
174 
 
 ASTRONOMY. 
 
 332. The apparent direction of these spots over the Sun's disc 
 is continually varying. Sometimes they seem to move across it 
 in straight lines, at others in curve lines. Sometimes the spots 
 seem to move upward, as they cross from east to west, while at 
 other times they incline downward, while the curve lines are 
 sometimes convex towards one pole of the Sun, and sometimes 
 towards the other. 
 
 333. All these phenomena are owing to the fact that the axis 
 of the Sun is inclined to the ecliptic, so that viewing him from 
 different points in the Earth's orbit, the apparent direction of 
 the spots must necessarily vary. The following diagrams may 
 serve to illustrate : 
 
 VARIOUS DIRECTIONS OF THE SOLAR SPOTS. 
 
 B C 
 
 I 
 
 March. 
 
 Jmve. 
 
 September. December. 
 
 Let E P represent the plane of the ecliptic. In March, the spots describe a curve, 
 which is convex to the south, as shown at A. In June, they cross the Sun's disc in nearly 
 straight lines, but incline upward. In September, they curve again, though in the oppo- 
 site direction ; and in December, pass over in straight lines, inclining downward. The 
 figures B and D show the inclination of the Sun's axis. 
 
 The following diagram will servo still further to illustrate the 
 cause of the change of direction of the solar spots. 
 
 SOLAR SPOTS OBSERVED FROM DIFFERENT POINTS. 
 
 Let the student imagine himself stationed upon the earth at A, in March, looking upon 
 the stm in the center, whose north or upper pole is now inclined toward him. The spots 
 will then curve Uvjiward. TJiree months afterward vis., in June the earth will be 
 
 832. In what general direction do these spots move ? What variations T 
 Is the oazwt' of these varying phenomena? 
 
 838. Whaf, 
 
THE SUN HIS DISTANCE, MAGNITUDE, ETC. 175 
 
 at B ; when the sun's axis will incline to tlie left, and the spots seem to pass upward to 
 the right. In three months longer, the observer will be at C, when the north pole of the 
 sun will incline/row iiim, and the spots seem to curve upward ; and in three months 
 longer, he will be at D, when the axis of the sun will incline to the right, and the spots 
 seem to incline downward. 
 
 334. From the regularity with which these spots revolve, it 
 is concluded, with good reason, that they adhere to the surface 
 of the Sun and revolve with it. They are all found within 30 
 of his equator, or within a zone 60 in width. 
 
 335. The apparent revolution of a spot, from any particular 
 point of the Sun's disc, to the same point again, is accomplished 
 in 27 days, 7 hours, 26 minutes, and 24 seconds ; but during 
 
 oat time, the spot has, in fact, gone through one revolution, 
 together with an arc, equal to that described by the Earth in 
 ner orbit in the same time ; which reducest he time of the Sun's 
 actual rotation on his axis, to 25 days, 9 hours, and 36 minutes. 
 
 Let S represent the sun, and A SIDEREAL AND SYNODIC REVOLUTION'S OF THE SUN. 
 the earth in her orbit. When she 
 is at A, a spot is seen upon the / 
 
 disc of the sun at B. The sun re- 
 volves in the direction of the ar- 
 rows, and in 25 days 10 hours the 
 spot comes round to B again, or 
 opposite the star E. This is a side- 
 real revolution. 
 
 During these 25 days 8 hours, 
 the earth has passed on in her 
 orbit some 25", or nearly, to C, 
 which will require nearly two days 
 for the spot at B to get directly 
 toward the earth, as shown at D. ^a&v 
 This last is a synodic revolution. 
 It consists of one complete revolu- * 
 
 tion of the sun upon his axis, and 
 about 27 over 
 
 336. The part of the Sun's disc not occupied by spots, is far 
 from being uniformly bright. Its ground is finely mottled with 
 an appearance of minute dark dots, or pores, which, attentively 
 watched for several days in succession, are found to be in a con- 
 stant state of change. 
 
 What the physical organization of the Sun may be, is a ques- 
 tion which astronomy, in its present state, cannot solve. It 
 seems, however, to be surrounded by an ocean of inexhaustible 
 flame, with dark spots of enormous size, now and then floating 
 upon its surface. From these phenomena, Sir W. Herschel sup- 
 posed the Sun to be a solid, dark body, surrounded by a vast 
 
 834. Are these spots supposed to adhere to the body of the Sun ? On what part of the 
 Sun arc they found ? 835. What is their time of apparent revolution ? The actual 
 time? How arrived at? 336. What said of the part of the Su-i about his poles? Of 
 his physical organization? What Joes it seem to be 9 How did Sir W. Hersrhol 
 regard it? 
 
176 ASTRONOMY. 
 
 atmosphere, almost always filled with luminous clouds, occasion- 
 ally opening and disclosing the dark mass within. 
 
 337. The speculations of Laplace were different. He im- 
 agined the solar orb to be a mass of fire, and the violent effer- 
 vescences and explosions seen on its surface, to be occasioned by 
 the eruption of elastic fluids, formed in its interior, and the spots 
 to be enormous caverns, like the craters of our volcanoes. 
 Others have conjectured that these spots are the tops of solar 
 mountains, which are sometimes left uncovered by the luminous 
 fluid in which they are immersed. 
 
 338. Among all the conflicting theories that have been 
 advanced, respecting the physical constitution of the Sun, there 
 is none entirely free from objection. The prevailing one seems 
 to be, that the lucid matter of the Sun is neither a liquid sub- 
 stance, nor an elastic fluid, but that it consists of luminous 
 clouds, floating in the Sun's atmosphere, which extends to a 
 great distance, and that these dark spots are the opaque body 
 of the Sun, seen through the openings in his atmosphere. Iler- 
 schel supposes that the density of the luminous clouds need not 
 be greater than that of our Aurora Borealis, to produce the 
 effects with which we are acquainted. 
 
 339. The similarity of the Sun to the other globes of Jie sys- 
 tem, in its s ipposed solidity, atmosphere, surface diver c jedwith 
 mountains and valleys, and rotation upon its axis, has ied to the 
 conjecture that it is inhabited, like the planets, by beings whose 
 organs are adapted to their peculiar circumstances. Such was 
 the opinion of the late Dr. Herschel, who .observed it unremit- 
 tingly, with the most powerful telescopes, for a period of fifteen 
 years. Such, too, was the opinion of Dr. Elliot, who attributes 
 to it the most delightful scenery ; and, as the light of the Sun 
 is eternal, so, he imagined, were its seasons. Hence he infers 
 that this luminary offers one of the most blissful habitations for 
 intelligent beings of which we can conceive. 
 
 887. Laplace's speculations? What other opinions? 838. Is there a satisfactory 
 theory of the physical nature of the Sun? State the prevailing i ne ? Herschel's suppo- 
 sition? 839. What conjecture in regard to the inhabitants of the Sun, and is; 1 :, a 
 *hat f< unded ? Who held to this idea ? 
 
y 
 
 TOE PRIMARY PLANETS MERCURY AND VENUS. 177 
 
 CHAPTER III. 
 
 THE PRIMARY PLANETS-MERCURY AND VENUS. 
 
 340. MERCURY is the nearest planet to the Sun that has yet 
 been discovered , and with the exception of the asteroids, is the 
 smallest. Its diameter is about 3,000 miles. Its bulk, therefore, 
 is about sixteen times less than that of the Earth. It would 
 require more than twenty millions of such globes to compose a 
 body equal to the Sun. 
 
 Here the student should refer to the diagrams, exhibiting the relative magnitudes and 
 distances of the Sun and Planets, Map I. And whenever this subject recurs in the course 
 of this work, the student should recur to the figures of this Map, until he is able to form 
 in his mind distinct conceptions of tne relative magnitudes and distances of all the 
 planets. The Sun and planets being spheres, or nearly so, their relative bulks are esti- 
 mated by comparing the cubes of their diameters : thus, the diameter of Mercury being 
 8,140 miles, and that of the Earth 7,912 ; their bulks are as the cube of 8,140, to the cube 
 of 7,912, or as 1 to 16, nearly. 
 
 K341. Mercury revolves on its axis from west to east in 24 
 hours, 5 minutes, and 28 seconds ; which makes its day about 
 10 minutes longer than ours. It performs its revolution about 
 the Sun in a few minutes less than 88 days, and at a mean dis- 
 tance of nearly 37,000,000 of miles. The length of Mercury's 
 year, therefore, is equal to about three of our months. 
 
 The rotation of a planet on its axis, constitutes its day ; its revolution about the Sun 
 Constitutes its year. 
 
 342. Owing to the dazzling brightness of Mercury, the swift- 
 ness of its motion, and its nearness to the Sun, astronomers 
 have made but comparatively few discoveries respecting it. 
 When viewed through a telescope of considerable magnifying 
 power, it exhibits at different periods all the various phases of 
 the Moon ; except that it never appears quite full, because its 
 enlightened hemisphere is never turned directly towards the 
 Earth, only when it is behind the Sun, or so near to it as to be 
 hidden by the splendor of its beams. Its enlightened hemisphere 
 being thus always turned towards the Sun, and the opposite one 
 being always dark, prove that it is an opaque body, similar to 
 the Earth, shining only in the light which it receives from the 
 Sun. 
 
 343. Mercury is not only the most dense of all the planets, 
 but receives from the Sun six and a half times as much light and 
 
 840. Subject of Chapter III. ? Size and position of Mercury ? What map illustrates 
 this subject? 841. State the time of Mercury's revolution upon his axis? How doe:i 
 tlr'i compare with the Earth? His period of revolution around the Sun ? 842. What 
 eaid of discoveries upon Mercury, his phases, &c. ? What proof that he is opaque ? 
 
178 
 
 ASTRONOMY. 
 
 heat as the Earth. The truth of this estimate, of course, 
 depends upon the supposition that the intensity of solar light and 
 heat at the planets, varies inversely as the squares of their dis- 
 tances from the Sun. 
 
 PHILOSOPHY OF THB DIFFUSION OP LIGHT. 
 
 In this diagram the light is seen passing in right lines, from the sun on the left toward 
 the several planets on the right. It is also shown that the surfaces A, B, and C receive 
 equal quantities of light, though B is four times, and C nine times as large as A ; and as 
 the light falling upon A is spread over four times as much surface at B, and nine times as 
 much at C, it follows that it is only one-ninth as intense at C, and one-fourth at B, as it 
 is at A. Hence the rule, that the light and heat of the planet is, inversely, as the squa re* 
 of their respective distances. 
 
 The student may not exactly understand this last statement. The square of any num. 
 ber is its product, when multiplied by itself. Now suppose we call the distances A, B, 
 and C, 1, 2, and 3 miles. Then the square of 1 is 1 ; the square of 2 is 4; and the square 
 of 3 is 9. The light and heat, then, would be in inverse proportion at these three points, 
 as 1, 4, and 9 ; that is, four times less at B than at A, and nine times less at 0. These 
 amounts we should state as 1, M. and one-ninth. 
 
 344. This law of analogy, did it exist with rigorous identity 
 at all the planets, would be no argument against their being 
 inhabited ; because we are bound to presume that the All-wise 
 Creator has attempered every dwelling-place in his empire to the 
 physical constitution of the beings which he has placed in it. 
 
 From a variety of facts which have been observed in relation to the production of 
 r.aloric, it does not appear probable, that the degree of heat on the surface of the differ- 
 ent planets depends on their respective distances from the Sun. It is more probable, that 
 it depends chiefly on the distribution of the substance of caloric on the surfaces, and 
 throughout the atmospheres of these bodies, in different quantities, according to the dif- 
 ferent situations which they occupy in the solar system ; and that these different quanr 
 tities of caloric are put into action by the influence of the solar rays, so as to produce 
 that degree of sensible heat requisite to the wants, and to the greatest benefit of each of 
 the planets. On this hypothesis, which is corroborated by a great variety of facts and 
 experiments, there may be no more sensible heat experienced on the planet Mercury, 
 than on the surface of Herschel, which is fifty times farther removed from the Sun. 
 
 345. The rotation of Mercury on its axis, was determined 
 from the daily position of its horns, by M. Schroeter, who not 
 only discovered spots upon its surface, but several mountains in 
 its southern hemisphere, one of which was lOf miles high 
 nearly three times as high as Chimborazo, in South America. 
 
 843. His density, and light and heat? Upon what rule is this estimate based? 844. 
 Would not this law of analogy make against the doctrine that the planets are inhab- 
 ited ? Is it probable that this law does prevail? Upon what may the relative heat of the 
 pJanets depend? 345. How was his diurnal revolution determined, and by whomV 
 What said of his surface ? What observation respecting mountains in general ? 
 
ME PRIMARY PLANETS MERCURY AND VENUS. 179 
 
 U is worthy of observation, that the highest mountains which have been discovered ii, 
 Mercury, Venus, the Moon, and perhaps we may add the Earth, are all situated in theii 
 southern hemispheres. 
 
 346. During a few days in March and April, August and Sep- 
 tember, Mercury may be seen for several minutes, in the morn- 
 ing or evening twilight, when its greatest elongations happen io 
 those months ; in all other parts of its orbit, it is too near the 
 Sun to be seen by the naked eye. The greatest distance that it 
 ever departs from the Sun, on either side, varies from 16 12', 
 to 28 20', alternately. 
 
 The distance of a planet from the Sun, as seen from the Earth 
 (measured in degrees), is called its elongation. The greatest 
 absolute distance of a planet from the Sun is denominated its 
 aphelion, and the least its perihelion. 
 
 347. The revolution of Mercury about the Sun, like that of 
 all the planets,* is performed from west to east, in an orbit which 
 is nearly circular. Its apparent motion, as seen from the Earth, 
 is, alternately, from west to east, and from east to west, nearly 
 in straight lines ; sometimes directly across the disc of the Sun, 
 but at all other times either a little above or a little below it. 
 
 Were the orbits of Mercury and Venus in the same plane with that of the Earth, they 
 would cross the Sun's disc at every revolution ; but as one-half of each of their orbits ia 
 fbo<ve, and the other half below the ecliptic, they generally appear to pass either above 
 or below the Sun. 
 
 Let the right line A, joining the Earth and the Sun in the above diagram, represent 
 the plane of the ecliptic. Now when an interior planet is in this plane, as shown at A, 
 it may appear to be upon the Sun's disc ; but if it is either above or below the ecliptic, 
 as shown at B and C, it will appear to pass either above or below the Sun, as shown at 
 D and E. 
 
 For the relative position of the planets' orbits, and their inclination to the plane of the 
 ecliptic, see 1, of the Atlas. Here the dotted lines continued from the dark lines, 
 denote the inclination of the orbits to the plane of the ecliptic, which inclination is 
 marked in figures on them. Let the student fancy as many circular pieces of paper 
 intersecting each other at the several angles of inclination marked on the Map, and be 
 will be enabled to understand more easily what is meant by the " inclination of the 
 planets' orbits." 
 
 348. Being commonly immersed in the Sun's rays in the even- 
 ing, and thus continuing invisible till it emerges from them in 
 the morning, Mercury appeared to the ancients like two distinct 
 stars. A long series of observations was requisite, before they 
 
 846. When may Mercury be seen? Why not at other times? How far does it depart 
 from the Sun on either side? What is meant by the elongation of a planet ? Its aphe- 
 lion and perihelion f 347. In what direction do the planets revolve around the Sun ? 
 What is the apparent motion of Mercury? Do they ever cross the Sun's disc? W v f 
 aot at every revolution? 848. How svas Mercury regarded by the ancients? 
 
180 
 
 ASTRONOMY. 
 
 recognized the identity of the star which was seen to recede 
 from the Sun in the morning with that which approached it it 
 the evening. But as the one was never seen until the other 
 disappeared, both were at last found to be the same planet, which 
 thus oscillated on each side of the Sun. 
 
 349. Mercury's oscillation from west to east, or from east to 
 west, is really accomplished in just half the time of its revolution, 
 which is about 44 days ; but as the Earth, in the mean time, 
 follows the Sun in the same direction, the apparent elongations 
 will be prolonged to between 55 and 65 days. 
 
 350. The passage of Mercury or Venus directly between the 
 Earth and the Sun, and apparently over this disc, is called a 
 Transi*. A transit can never occur except when the interior 
 planet is in or very near the ecliptic. The Earth* and the planet 
 must be on the same side of the ecliptic ; the planet being at. 
 one of its nodes, and the Earth on the line of its nodes. 
 
 This cut represents the ecliptic and zodiac 1 , with the orbit of an interior planet, hia 
 node*, &c. Tht line of his nodes is, as shown, in the 16" of 8 and the 16 of Tit. Now if 
 the earth is in e , on the line L N, as shown in the cut, when Mercury is at his ascending 
 node (ft), he will seem to pass upward over the Sun's face, like a dark spot, as repre- 
 sented in the figure. On the other hand, if Mercury is at his descending node ($), 
 when the earth is in the 16* of TTJ,, the former will seem to pass downward across the 
 dive of the Sun. 
 
 351. As the nodes of his orbit are on opposite sides of the 
 ecliptic, and are passed by the Earth in May and November, it 
 follows that all transits of Mercury must occur in one or the 
 other of these months. They are, therefore, called the Node 
 months. As is shown in the diagram, the Earth passes the 
 
 849. In what time is the oscillation of Mercury from east to west really accomplUhf-iV 
 Wh:it is the apparent time, and why? 350. What is a transit T When do they occur r t 
 What are the nod,'* of a planet's orbit? The tine of the node* 851. What ur the 
 
THE PR, MARY PLANETS MERCURY AND VENUS. 181 
 
 TOAKSITS OP MBROUBT. 
 NORTH 
 
 ascending Node of Mercury in November, and the descending in 
 May ; the former of which is in the 16th degree of Taurus, and 
 the latter in the 16th degree of Scorpio. 
 
 All the transits of Mercury ever noticed have occurred in one or the other of thcco 
 months, and for the reason already assigned. The first ever observed took place Novem- 
 ber 6, 1631 ; since which time there have been 29 others by the same planet in all 80 
 8 in May, and 22 in November. 
 
 352. The last transit of Mercury occurred November 11, 1861 ; 
 and the next will take place November 4, 1868. Besides this, 
 there will be four more during the present century two in May, 
 and two in November. 
 
 The accompanying cut is a de- 
 lineation of all the transits of Mer- 
 cury from 1802 to the close of the 
 present century. The dark line 
 running east and west across the 
 Sun's center represents the plane 
 of the ecliptic, and the dotted lines 
 the apparent paths of Mercury in 
 the several transits. The planet 
 is shown at its nearest point to the 
 Sun's center. Its path in the last 
 transit and in the next will easily 
 be found. 
 
 The last transit of Mercury was 
 observed in this country by Pro- 
 fessor Mitchel, at the Cincinnati 
 Observatory, and by many others 
 both in America and in Europe. 
 The editor had made all necessary 
 preparation for observing the phe- 
 nomenon at his residence, near 
 Oswego, New York ; but, unfor- 
 tunately, his sky was overhung 
 with clouds, which hid the sun 
 from his view, and disappointed all 
 his hopes. 
 
 353. By comparing the mean motion of any of the planets 
 with the mean motion of the Earth, we may readily determine 
 the periods in which they will return to the same points of their 
 orbit, and the same positions with respect to the Sun. The 
 knowledge of these periods will enable us to determine the hour 
 when the planets rise, set, and pass the meridian, and in general 
 all the phenomena dependent upon the relative position of the 
 Earth, the planet and the Sun ; for at the end of one of these 
 periods they commence again, and all recur in the same order. 
 
 We have only to find a number of sidereal years, in. which the planet completes 
 exactly, or very nearly, a certain number of revolutions; that is, to find such a number 
 if planetary revolutions, as, when taken together, shall be exactly equal to one, or any 
 lumber of revolutions of the Earth. In the case of Mercury this ratio will be as 87.909 
 s to 365.256. Whence find that, 
 
 SOUTH 
 
 node montlm of a planet? The node months of Mercury? 352. When did the last 
 transit of Mercury occur? When will the next take place? What ethers during the 
 present century? What said of the last transit of Mercury ? 353. How may we deter- 
 aius when 'rj'iiH'-s will occur? What ratio is found between the revolutions o f Mercury 
 
182 
 
 ASTRONOMY. 
 
 7 periodical revolutions of the Earth are equal to 29 of Mercury - 
 18 periodical revolutions of the Earth are equal to 54 of Mercury : 
 33 periodical revolutions of the Earth are equal to 137 of Mercury : 
 46 periodical revolutions of the Earth are equal to 191 of Mercury. 
 
 Therefore, transits of Mercury, at the same node, may happen at intervals of 7, 13-, 33, 46-. 
 
 <kc. years. Transits of Venus, as well as eclipses of the Sun and Moon, are calculated 
 
 upon the same principle. 
 The following is a list of all the Transits of Mercury from the time the first was observotl 
 
 by Gassendi, November 6, 1631, to the end of the present century : 
 
 1631 Nov. 6. 
 1644 Nov. 6. 
 1651 Nov. 2. 
 1661 May 3. 
 1664 Nov. 4. 
 1674 May 6. 
 1677 Nov. 7. 
 1690 Nov. 9. 
 1697 Nov. 2. 
 
 1707 May 5. 
 1710 Nov. 6. 
 1723 Nov. 9. 
 1736 Nov. 10. 
 1740 Nov. 2. 
 1743 Nov. 4. 
 1753 May 5. 
 1756 Nov. 6. 
 1769 Nov. 9. 
 
 1776 Nov. 2. 
 1782 Nov. 12. 
 1786 May 3. 
 1789 Nov. 5. 
 1799 May 7. 
 1802 Nov. 8. 
 1815 Nov. 11. 
 1822 Nov. 4. 
 1832 May 5. 
 
 1835 Nov. 7. 
 1845 May 8 
 1848 Nov. 9. 
 1861 Nov. 11. 
 1868 Nov. 4. 
 1878 May 6. 
 1881 Nov. 7. 
 1891 May 9. 
 1894 Nov. 10. 
 
 354. The sidereal revolution of a planet respects its absolute 
 motion ; and is measured by the time the planet takes to revolve 
 from any fixed star to the same star again. The synodical revo- 
 lution of a planet respects its relative motion ; and is measured 
 by the time that a planet occupies in coming back to the same 
 position with respect to the Earth and the Sun. 
 
 SIDEREAL AXD SYNODIC BEVOLUTIOM3. 
 
 In the adjoining cut the revolution of 
 
 ..--"" """-.. the Earth from A, opposite the star B, 
 
 around to the same point again, would be 
 a sidereal revolution. 
 
 Suppose the Earth and Mercury to start 
 together from the points A C (where Mer- 
 cury would be in inferior conjunction with 
 the Sun), and to proceed in the direction 
 of the arrows. In 88 days Mercury would 
 come around to the same point again ; 
 but as the Earth requires more than four 
 times that number of days for a revolu- 
 tion, she will only have reached the point 
 D when Mercury arrives at C again ; so 
 that they will not be in conjunction, and a 
 synodic revolution will not be completed 
 by Mercury. He starts on, however, in 
 his second round, and constantly gaining 
 upon the Earth, till in 27 days from the 
 time he left C the second time, he over- 
 takes the Earth at E and F, and is again in 
 inferior conjunction. 
 
 from this illustration, it will be seen that the synodic revolution of a planet must 
 always require more time than the sidereal. 
 
 355. The absolute motion of Mercury in its orbit is 109,157 
 miles an hour ; that of the Earth is 68,288 miles ; the differ- 
 ence, 41,469 miles, is the mean relative motion of Mercury, with 
 respect to the Earth. 
 
 The sidereal revolution of Mercury is 87d. 23h. 15m. 44s. Its synodical revolution ie 
 
 and the Earth? 354. What is a sidereal revolution of a planet? A synodic.alY 
 855. What is the absolute motion of Mercury in his orbit? What is that of the Earth? 
 The difference, or relative motion of Mercury? What is his sidereal period? His 
 uynoditi t II .T is the latter ascertained? 
 
THE PRIMARY PLANETS MERCURY AND VENUS. 183 
 
 found by dividing the wh< fe circumference of 360 by its relative motion in respect to the 
 tearth. Thus, the mean daily motion of Mercury is 14782" .565; that of the Earth is 
 8548". 318 ; and their difference is 11184'. 237, being Mercury's relative motion, or what it 
 gains on the Earth every day. Now by simple proportion, 11184".237 is to 1 day, as 360* 
 is to 115d. 21h. 8', 24", the period of a synodical revolution of Mercury. 
 
 VENUS. 
 
 356. There are but few persons who have not observed a 
 beautiful star in the west, a little after sunset, call the evening 
 star. This star is Venus. It is the second planet from the 
 Sun. It is the brightest star in the firmament, and on this 
 account easily distinguished from the other planets. 
 
 If we observe this planet for several days, we shall find that 
 it does not remain constantly at the same distance from the Sun, 
 but that it appears to approach, or recede from him, at the rate 
 of about three-fifths of a degree every day ; and that it is some- 
 times on the east side of him, and sometimes on the west, thus 
 continually oscillating backwards and forwards between certain 
 limits. 
 
 357. As Venus never departs quite 48 from the Sun, it is 
 never seen at midnight, nor in opposition to that luminary ; 
 being visible only about three hours after sunset, and as long 
 before sunrise, according as its right ascension is greater or less 
 than that of the Sun. At first, we behold it only a few minutes 
 after sunset ; the next evening we hardly discover any sensible 
 change in its position ; but after a few days, we perceive that 
 it has fallen considerably behind the Sun, and that it continues 
 to depart farther and farther from him, setting later and later 
 every evening, until the distance between it and the Sun is 
 equal to a little more than half the space from the horizon to the 
 zenith, or about 46. It now begins to return toward the Sun, 
 making the same daily progress that it did in separating from 
 him, and to set earlier and earlier every succeeding evening, 
 until it finally sets with the Sun, and is lost in the splendor of 
 his light. 
 
 358. A few days after the phenomena we have now described, 
 we perceive, in the morning, near the eastern horizon, a bright 
 star which was not visible before. This also is Venus, which is 
 now called the morning star. It departs farther and farther 
 from the Sun, rising a little earlier every day, until it is seen 
 
 856. Describe Venus. What called? Distance from the Sun ? What change of posi- 
 tion observable ? 357. Greatest distance to which she departs from the Sun? What 
 Consequence' How and when seen? 358. What next after these phenomena? 
 
184 ASTRONOMY. 
 
 about 46 west of him, where it appears stationary for a few 
 days ; then it resumes its course towards the Sun, appearing 
 later and later every morning, until it rises with the Sun, and 
 we cease to behold it. In a few days, the evening star again 
 appears in the west, very near the setting sun, and the same 
 phenomena are again exhibited. Such are the visible appear- 
 ances of Yenus. 
 
 359. Yenus revolves about the Sun from west to east in 224 1 
 days, at the distance of about 69,000,000 of miles, moving in 
 her orbit at the rate of 80,000 miles an hour. She turns 
 around on her axis once in 23 hoars, 21 minutes, and 7 seconds. 
 Thus her day is about 25 minutes shorter than ours, while her 
 year is equal to 7 of our months, or 32 weeks. 
 
 360. The mean distance of the Earth from the Sun is estimated 
 at 95,000,000 of miles, and that of Yenus being 69,000,000, 
 the diameter of the Sun, as seen from Yenus, will be to his 
 diameter as seen from the Earth, as 95 to 69, and the surface 
 of his disc as the square of 95 to the square of 69, that is, 
 as 9025 to 4761, or as 2 to 1, nearly. The intensity of light 
 and heat being inversely as the square of their distances from 
 the Sun (No. 342), Yeuus receives twice as much light and heat 
 as the Earth. 
 
 361. The orbit of Yenus is within the orbit of the Earth ; 
 for if it were not, she would be seen as often in opposition to the 
 Sun, as in conjunction with him ; but she was never seen rising 
 in the east while the Sun was setting in the west. Nor was she 
 ever seen in quadrature, or on the meridian, when the Sun was 
 either rising or setting. Mercury's greatest elongation being 
 about 23 from the Sun, and that of Yenus about 46, the orbit 
 of Yenus must be outside of the orbit of Mercury. 
 
 362. The diameter of Yenus is about 7.900 miles ; bnt, her 
 apparent diameter and brightness are constantly varying, accord- 
 ing to her distance from the Earth. When Yenus and tho 
 Earth are on the same side of the Sun, her distance from tho 
 Earth is only 26,000,000 of miles ; when they are on opposite 
 sides of the Sun, her distance is 164,000,000 of miles. Were 
 the whole of her enlightened hemisphere turned towards us, 
 when she is nearest, she would exhibit a light and brilliancy 
 
 859. What is Venus' sidereal period ? Distance from the Sun ? Rate of motion 
 Time of rotation upon her axis? How, then, do her day and year compare with ours? 
 800. How must the Sun appear from Venus, and why? What of her light and heat? 
 861- Where .8 the orbit of Venus situated? What proof of this? 362. Venus' diame- 
 ter ? lljr apparent diameter? State her least and greatest distances from the Earth 
 
THE PRIMARY PLANETS MERCURY AND VENUS. 185 
 
 twenty-five times greater than she generally does, and appear 
 like a smaU brilliant moon ; but, at that time, her dark hemi- 
 sphere is turned towards the Earth. 
 
 When Venu_ approaches nearest to the Earth, her apparent, or observed diameter iu 
 61".2; when most remote, it is only 9". 6 ; now 61".2--9*.6=6?i. hence when nearest the 
 Earth her apparent diameter is G 3 , times greater than when most distant, and surface 
 of her disc (/t)- or nearly 41 times greater. In this work, the apparent size of the 
 heavenly bodies is estimated from the apparent surface of their discs, which is always 
 proportional to the squares of their apparent diameters. 
 
 363. Mercury and Venus are called Interior planets, because 
 their orbits are within the Earth's orbit, or between it and the 
 Sun. The other planets are denominated Exterior, because their 
 orbits are without or beyond the orbit of the Earth. (Map I.) 
 As the orbits of Mercury and Venus lie within the Earth's orbit, 
 it is plain, that once in every synodical revolution, each of these 
 planets will be in conjunction on the same side of the Sun. In 
 the former case, the planet is said to be in its inferior conjunc- 
 tion, and in the latter case, in its superior conjunction ; as in the 
 following figure. 
 
 MARS IN CONJUNCTION 
 
 e- ... 
 
 <5 "-, 
 
 Let the student imagine him- 
 self stationed upon the earth in 
 the cut. Then the sun and three 
 planets above are in conjunc- 
 tion. The inferior and supe- 
 rior are distinguished ; while at 
 A, a planet is shown in quadra- 
 ture, and at the bottom of the 
 cut the planet Mars in opposi- 
 tion with the sun and interior 
 planet. 
 
 The period of Venus' synodi- 
 cal revolution is found in the 
 same manner as that of Mer- 
 cury ; namely, by dividing the 
 whole circumference of her orbit 
 by her mean relative motion in 
 a day. Thus, Venus' abnolitte 
 mean daily motion is 1 36' 7'.8, 
 the Earth's is 59' 8'.3, and theii 
 difference it, 36' W.5. Divide 
 860 by 86' 59".5, and it gives 
 583.920, or nearly 584 days for 
 Venus' synodical revolution, or 
 the period in which she is 
 twice in conjunction with the 
 MARS IN "OPPOSITION Earth. 
 
 364 When Venus' right ascension is less than that of the 
 Sun, she rises before him ; when greater, she appears after his 
 setting. She continues alternately morning and evening star, 
 for a period of 292 days, each time. 
 
 How would she appear if we saw her enlightened side when nearest to us? What com- 
 putation in the fine print? 363. How are Mercury and Venus distinguished, and why ? 
 What said of conjunctions ! Describe the inferior and superior ? How is the period of 
 Venus' synodical revolution found 3G4. When is Venus evening star Morningy 
 
186 ^STKONOMY. 
 
 To those "vho are but little acquainted with astronomy, it will seem strange, at first, 
 that Venus nhould apparently continue longer on the east or west side of the Sun, than 
 the whole time of her periodical revolution around him. But it will be easily understood, 
 when it is considered, that while Venus moves around the Sun, at the rate of about 1* 36' 
 of angular motion per day, the Earth follows at the rate of 59' ; so that Venus actually 
 gains on the Earth, only 87' in a day. 
 
 Now it is evident that both planets will appear to keep on the same side of the Sun, 
 until Venus has gained half her orbit, or 180 in advance of the Earth ; and this, at a 
 mean rate, will require 292 days, since 292 x 37' =10804', or 180 nearly. 
 
 365. Terms passes from her inferior to her superior conjunc- 
 tion in about 292 days. At her inferior conjunction, she is 
 26,000,000 of miles from the Earth ; at her superior conjunc- 
 tion, 164,000,000 of miles. It might be expected that her bril- 
 liancy would be proportionally increased, in the one case, and 
 diminished in the other ; and so it would be, were it not that 
 her enlightened hemisphere is turned more and more from us, as 
 she approaches the Earth, and comes more and more into view 
 as she recedes from it. It is to this cause alone that we must 
 attribute the uniformity of her splendor, as it usually appears to 
 the naked eye. 
 
 366. Mercury and Venus present to us, successively, the 
 various shapes and appearances of the Moon ; waxing and 
 waning through different phases, as shown in the following cut, 
 from the beautiful crescent to the full rounded orb. This fact 
 shows, that they revolve around the Sun, and between the Sun 
 and the Earth. 
 
 PHASES OF VEXUS AS SHE REVOLVES ARODHD TES SUK. 
 
 It should be remarked, however, that Venus is never seem, when she is entirely full., 
 except once or twice in a century, when she passes directly over the Sun's disc. At 
 every other conjunction, she is either behind the Sun, or so near him as to be hidden by 
 tlie splendor of his light. The preceding diagram better illustrates the various appear- 
 ances of Venus, as she moves around the Sun, than any description of them could do. 
 
 367. From her inferior to her superior conjunction, Venus, 
 appears on the west side of the Sun, and is then our morning 
 
 How long each? How is it that Venus is east ur west of the Sun 292 days, when her 
 periodic revolution is performed in about '225 days ? 365. What is the time from one 
 ;onjunction of Venus to another? Is her brilliancy in proportion to her nearness? Why 
 .lot? 366. What phases do Mercury and Venus exhibit, and what do they prove? 
 /Vr<.' they ever soon entirely full t 367. When is Veiius morning star? When evening? 
 

 THE PRIMARY PLANETS - MERCURY AND VENUS. 187 
 
 star ; from her superior to her inferior conjunction she appears 
 on the east side of the Sun, and is then our evening star. These 
 phenomena are illustrated by the following diagram. 
 
 TESCS AS MORNING AND EVENING STAIl. 
 
 Let the student hold the book up south of him, and he will at once Bee why Venus is 
 alternately morning and evening star. Let the plane A B represent tlio sensible or visi- 
 ble horizon, C D the apparent daily path of the Sun through the heavens, and E the 
 Earth in her apparent position. The Sun is shown at three different points namely, 
 rising in the east, on the meridian, and setting in the west; while Venus is seen revolving 
 around him from west to east, or in the direction of the arrows. Now it is obvious that 
 when Venus is at F, or west of the Sun, she sets before him as at G, and rises before him 
 as at H. She must, therefore, be morning star. On the other hand, when she is ea-nt 
 of the Sun, as at J, she lingers in the west after the Sun has gone down, as at K, and is 
 consequently evening star. 
 
 In this cut, Venus would be at her greatest elongation eastward at J, and westward 
 at F, and in both cases would be "stationary." At L and M she would be in conjunc- 
 tion with the Sun. 
 
 Were the earth to suspend her daily rotation, with the Sun on the meridian of the 
 observer, as represented at L, we might readily watch Venus through her whole circuit 
 around the Sun. 
 
 368. Like Mercury, Yenus sometimes seems to be stationary. 
 Her apparent motion, like his, is sometimes rapid ; at one time, 
 direct, and at another, retrograde. ; vibrating alternately back- 
 wards and forwards, from west to east, and from east to west. 
 These vibrations appear to extend from 45 to 41, on each side 
 of the Sun. 
 
 Consequently she never appears in the eastern horizon more than three hours before 
 sunrise, nor continues \onger in the western horizon after sunset. Any star or planet 
 therefore, however brilliant it may appear, which is seen earlier or later than this, cannot 
 be Venus. 
 
 369. In passing from her western to her eastern elongation, 
 
 268. Is she ever stationary? What other irregularities in her apparent motion? 
 SCO. When is her motion direct? When retrograde? When most rapid? When 
 
188 
 
 ASTRONOMY. 
 
 her motion is from west to east, in the order of the signs ; it is 
 thence called direct motion. In passing from her eastern to her 
 western elongation, her motion with respect to the Earth is 
 from east to west, contrary to the order of the signs ; it is 
 thence denominated retrograde motion. Her motion appears 
 quickest about the time of her conjunctions ; and she seems sta- 
 tionary at her elongations. She is brightest about thirty-six 
 days before and after her inferior conjunction, when her light is 
 so great as to project a visible shadow in the night, and some- 
 times she may be seen with the naked eye even at noon-day. 
 
 DIKKCT .iND RCTROGIIADK KOTIOHS. 
 
 The cause of the apparent re- 
 trogression of the interior planets 
 is the fact that they revolve much 
 more rapidly than the earth, from 
 which we view them ; causing 
 their direct motion to appear to 
 be retrograde. 
 
 Suppose the earth to be at A, and Venus at 
 B, she would appear to be at C, among the 
 stars. If the earth remained at A while 
 Venus was passing from B to D, she would 
 seem to retrograde from C to E; but as the 
 earth passes from A to F while Venus goei 
 from B to D, Venus will appear to be at G ; 
 and the amount of her apparent westward 
 motion will only be from C to G, 
 
 370. If the orbit of Yenus lay 
 exactly in the plane of the Earth's 
 orbit, she would pass centrally 
 across the Sun's disc, like a dark 
 round spot, at every inferior conjunction ; but, as one-half 
 of her orbit lies about 3i above the ecliptic, and the other half 
 as far below it, she will always pass the Sun a very little above 
 or below it, except when her inferior conjunction happens in, or 
 near one of her nodes ; in which case she will make a transit. 
 (See cuts, pages 179 and 180.) 
 
 This phenomenon, therefore, is of very rare occurrence ; it can 
 happen only twice in a century ; because it is only twice in that 
 time that any number of complete revolutions of Venus are just 
 or nearly equal to a certain number of the Earth's revolutions. 
 
 The principle which was illustrated in predicting the transits of Mercury, applioa 
 equally well to those of Venus ; that is, we must find such sets of numbers (representing 
 
 orightest? State the cause of the apparent retrograde motion? 870. Why have we not 
 i transit at every revolution of Venus? How frequent, therefore? Uow predicted I 
 When do her nodes cut the ecliptic? 
 
THE PR MARY PLANETS - MERCURY AND VENUS. 180 
 
 complete revolutions of the Earth and Venus) as shall be to each other in the ratio cf 
 tLir periodical times, or as 3'55.256 is to 2'24.7. Thus : the motion of Venus, in the Julian 
 pears, is 21t;6691'.52 ; that of the Earth for the same period being 129G27'.45, the ratio 
 will be ^Sr^'Vy *'^f- As tne * wo terms of this fraction cannot be reduced by a com 
 inon divisor, we must multiply them by such numbers as will make one a multiple of the 
 other; accordingly, 13 times the denominator will be nearly equal to 8 times the nume- 
 rator ; and 475 times the der^^minator will equal 291 times the numerator. 
 
 By combining these two periods and their multiples by addition and subtraction, wo 
 shall obtain tlie period of all the transits that have ever happened. Thus : 2918 x 7=235, 
 another period ; and 2916 x 8=243, another period, and so on. " Whence we find that 
 
 8 periodical revolutions of the Earth are equal to 13 of Venus: 
 235 periodical revolutions of the Earth are equal to 382 of Venus : 
 243 periodical revolutions of the Earth are equal to 395 of Venus: 
 251 periodical revolutions of the Earth are equal to 4(>S of Venus : 
 291 periodical revolutions of the Earth are equal to 475 of Venus. 
 
 Hence a transit of Venus may happen at the same node, after an interval of 8 years, 
 but if it do not happen then, it cannot take place again at the same node, in less than 
 235 years. The orbit of Venus crosses the ecliptic near the middle of Gemini and Sagit- 
 tarius; and those points mark the position of her nodes. At present, her ascending node 
 is in the 14th degree of Gemaii, and her descending node in the same degree of S-'.git- 
 tarius. 
 
 371. The node months of Yenus are December and Jane. 
 The line of her nodes lies in Gemini ( n ) and Sagittarius ( ) ; 
 and as the Earth always passes those points in the months 
 named, it follows that all transits of Yenus must occur in those 
 mouths for ages to come. 
 
 for as tho 
 will reach 
 
 that point in the ecliptic in one month after she passes the line of Mercury's nodes; so 
 that if his transits occur iuMay and November, hers should occur in June and December, 
 as is always the case. 
 
 272. The first transit ever known to have been seen by any 
 human being, took place at the ascending node, December 4th, 
 1639.* If to this date we add 235 years, we shall have the 
 
 * This phenomenon was first witnessed by Horrox, a young gentleman about 21 years 
 of age, living in an obscure village 15 miles north of Liverpool. The tables of Kepler, 
 constructed upon the observations of Tycho Brahe, indicated a transit of Venus in 1631, 
 but none was observed. Horrox, without much assistance from books and instruments, 
 set himself to inquire into the error of the tables, and found that such a phenomenon 
 might be expected to happen in lb'39. He repeated his calculations during this interval, 
 with all the carefulness and enthusiasm of a scholar ambitious of being the first to predict 
 and observe a celestial phenomenon, which, from the creation of the world, had never 
 Deen witnessed. Confident of the result, he communicated his expected triumph to A 
 confidential friend residing in Manchester, and desired him to watch for the event, and 
 to take observations. So anxious was Horrox not to fail of witnessing it himself, that he 
 commenced his observations the day before it was expected, and resumed them at the 
 rising of the Sun on the morrow. Hut the very Jiottr when his calculations led him to 
 ;xpect the visible appearance of Venus on the Sun's disc, wax ttlxo the appointed /tour 
 for the public wo.-ihip of God on the Sabbatk. The delay of a few minutes might 
 dtprive him for ever of an opportunity of observing the transit. If its very commence- 
 ment were no* noticed, clouds might intervene, and conceal it until the Sun should set: 
 a. id nearly u. century and a half would elapse before another opportunity would occur. 
 He had been waiting for the event with the most ardent anticipation for eight years, and 
 the result premised much benefit to the science. JfoticWu&inding oil thi, Horroto 
 twice tfunpended his observations and twice repaired to the llou*e of God, the Great 
 Author of the bright works he delighted to contemplate. When his duty was thus per- 
 
 871. Which are her node months V 372. When was the first transit observed ' What 
 
 fmcrtsting aiiecdo*cf 
 
 This proposition will be well understood by consulting the cut on page oOft ; fo 
 line of Venus' nodes is only one sign ahead of that of Mercury, the Earth wi 
 
190 ASTRONOMY. 
 
 time of the next transit at the same node, which will accordingly 
 happen in 1874. There will be another at the same node in 
 1882, eight years afterwards. It is not more certain that this 
 phenomenon will recur, than that the event itself will engross 
 the attention of all the astronomers then living upon the Earth. 
 It will be anticipated, and provided for, and observed, in every 
 inhabited quarter of the globe, with an intensity of solicitude 
 which no natural phenomenon, since the creation, has ever 
 excited. 
 
 373. The reason why a transit of Yenus should excite so great 
 an interest is, because it may be expected to solve an important 
 problem in astronomy, which has never yet been satisfactorily 
 done : a problem whose solution will make known to us the 
 magnitudes and masses of all the planets, the true dimensions of 
 their orbits, their rates of motion around the Sun, and their 
 respective distances from the Sun, and from each other. It may 
 be expected, in short, to furnish an universal standard of astro- 
 nomical measure. Another consideration will render the obser- 
 vation of this transit peculiarly favorable ; and that is, astrono- 
 mers will be supplied with better instruments, and more accurate 
 means of observation, than on any former occasion. 
 
 So important, says Sir John Herschel, have these observations appeared to astronomers, 
 that at the last transit of Venus, in 1769, expeditions were fitted out, on the most efficient 
 scale, by the British, French, Russian, and other governments, to the remotest corners of 
 the globe, for the express purpose of making them. The celebrated expedition of Captain 
 Cook to Otaheite, was one of them. The general result of all the observations made on 
 this most memorable occasion, gives 8".5776 for the Sun's horizontal parallax. 
 
 374. The phenomena of the seasons of each of the planets, 
 like those of the Earth, depend upon the inclination of the axis 
 of the planet to the plane of its orbit, and its revolution around 
 the Sun. The inclination of the axis of Yenus to the plane of 
 her orbit, though not precisely known, io commonly estimated at 
 75, as represented to the eye in the following cut : 
 
 rormed, and he had returned to his chamber the second time, his love of science waa 
 gratified with full success ; and he saw what no mortal eye had observed before ! 
 
 If anything can add interest to this incident, it is the modesty with which the young 
 astronomer apologizes to tlie world, for suspending his observations at all. 
 
 " I observed it," says he, " from sunrise till nine o'clock, again a little before ten, and 
 lastly at noon, and from one to two o'clock ; the rest of the day being devoted to highe" 
 duties, which might not be neglected for these pastimes." 
 
 When the next? When another? How will it be regarded ? 373. Why should sucn 
 an event excite general interest? Remark of Sir John Herschel ? What expedition and 
 what results? 374. Upon what do the s&^ons of the planets depend? What is tho 
 Inclination of Venus' axi^ t< the piane c .er orbit? How is her orbit situated vitli 
 referent to the ecliptic? 
 
THE PRIMARY PLANETS MERCURY AN1 VENUS. 191 
 
 IMJUNATIOK OF TKNCS' AXU. 
 
 The orbit of Venus departs from the ecliptic 8%', while her oasis is inclined to the 
 plane of her orbit 75, as shown in the above figure. This distinction should be kept 
 definitely in view by the student. 
 
 375. The declination of the Sun on each side of Venus' equa- 
 tor, must be equal to the inclination of her axis : and if this 
 extends to 75, her tropics are only 15 from her poles, and her 
 polar circles only 15 from her equator. It follows, also, that 
 the Sun must change his declination more in one day at Venus, 
 than in five days on the Earth ; and, consequently, that he never 
 shines vertically on the same places for two days in succession 
 This may, perhaps, be providentially ordered, to prevent the too 
 great effect of the Sun's heat, which, on the supposition that it 
 is in inverse proportion to the 'square of the distance, is twice as 
 great on this planet as it is on the Earth. 
 
 376. At each pole of Venus, the Sun continues half of her 
 year without setting in summer, and as long without rising in 
 winter ; consequently, her polar inhabitants, like those of the 
 Earth, have only one day and one night in the year ; with this 
 difference, that the polar days and nights of Venus are not quite 
 two-thirds as long as ours. 
 
 Between her polar circles, which are but 15 from her equator, 
 there are two winters, two summers, two springs, and two 
 autumns, every year. But because the Sun stays for some time 
 near the tropics, and passes so quickly over the equator, the win- 
 ters in that zone will be almost twice as long as the summers. 
 
 The north pole of Venus' axis inclines towards the 20th 
 degree o* Aquarius ; the Earth's towards the beginning of Can- 
 cer ; consequently, the northern parts of Venus have summer 
 in the signs where those of the Earth have winter, and vice versa. 
 
 377. When viewed through a good telescope, Venus exhibits 
 not only all the moon-like phases of Mercury, but also a variety 
 of inequalities on her surface ; dark spots, and brilliant shades, 
 hills and valleys, and elevated mountains. But on account of 
 
 875. What is the amount of the Sun's declination upon Venus ? What resu'ts ? What 
 supposed design in this arrangement? 376. What said of the polar regions of Venus V 
 What of her seasons ? How is her north pole situated with respect to the heftvcuu ? 
 What consequence? 877. Ilow does Venus appear through a telescope rj 
 
192 ASTRONOMY. 
 
 the great density of her atmosphere, these inequalities arc per- 
 ceived with more difficulty than* those upon the other planeis. 
 
 378. The mountains of Venus, like those of Mercury and tin 
 Moon, are highest in the southern hemisphere. According to 
 M. Schroeter, a celebrated German astronomer, who spent more 
 than ten years in observations upon this planet, some of her 
 mountains rise to the enormous height of from ten to twenty- 
 two miles. The observations of Dr. Herschel do not indicate so 
 great an altitude ; and he thinks, tht in general they are con- 
 siderably overrated He estimates the diameter of Venus at 
 8649 miles ; making her bulk more than one-sixth larger than 
 that of the Earth. Several eminent astronomers affirm, that 
 they have repeatedly seen Venus attended by a satellite, and 
 they have given circumstantial details of its size and appearance, 
 its periodical revolution and its distance from her. It is said to 
 resemble our Moon in its phases, its distance, and its magnitude. 
 Other astronomers deny the existence of such a bcdy, because 
 it was not seen with Venus on the Sun's disc, at the transits of 
 1761 and 1769. It probably does not exist. 
 
 THE EARTH. 
 
 379. The Earth is the place from which all our observations 
 of the heavenly bodies must necessarily be made. The apparent 
 motions of these bodies being very considerably affected by her 
 figure, motions, and dimensions, these hold an important place in 
 astronomical science. It will, therefore, be proper to consider, 
 first, some of the methods by which they have been determined. 
 
 If, standing on the sea-shore, in a clear day, we view a ship 
 leaving the coast, in any direction, the hull or body of the vessel 
 
 Why less distinct than the other planets? 37S. Where are her highest monntalns 
 Jituated? Their height? Remark <>f Dr. Herschel ? Hi* estimate of Venus' diameter ? 
 What said about a satellite around Venus? 879. Relation of the earth to the other 
 planets in the study of astronomy? What necessary, therefore? What proof of the 
 oonrexity of her surface? 
 
THE PRIMARY PLANETS THE EARTH. 
 
 193 
 
 6rst disappears ; afterwards the rigging, and lastly the top of 
 the mast vanishes from our sight. 
 
 CONVEXITY OP TUB HARTa'S SCKt'ACh. 
 
 Here the observer upon the shore at A sees only the topmasts of the ship, whi.e the 
 man standing upon the pillar at B sees the masts and sails, and part of the hull. Now, 
 if the water between A and the ship were exactly flat instead of convex, the vision of A 
 tfould extend along the line C, and he could see the whole ship as well as B. The advan- 
 'age of B over A, in consequence of his elevation, shows that the surface of the water 
 is convex between A and the ship. 
 
 380. Again : navigators have sailed quite around the Earth, 
 and thus proved its convexity. 
 
 CONVEXITY OF THE EARTH'S SURFACE. 
 
 Ferdinand Magellan, a Portuguese, was the 
 first who carried this enterprise into execution. 
 He embarked from Seville, in Spain, and directed 
 his course towards the west. After a long voy- 
 age, he descried the continent of America. Not 
 finding an opening to enable him to continue his 
 course in a westerly direction, he sailed along the 
 coast towards the south, till, coming to its south- 
 ern 3Xtremity, he sailed around it, and found 
 himself in the great Southern Ocean. He then 
 resumed his course towards the west. After 
 some time he arrived tit the Molucca Islands, in 
 the Eastern IJemi#p?u>re ; and sailing con- 
 tinually towards the west, he made Europe from 
 the ea?t, arriving at the place from which he 
 set out.* 
 
 The next who circumnavigated the Earth wag 
 Sir Francis Drake, who sailed from Plymouth, 
 December 13, 15T7, with five small vessels, and 
 arrived at the same place, September 26, 1580. 
 Since that time, the circumnavigation of the Earth has beeu performed by Cavendish, 
 Cordes, Noort, Sharten, Heremites, Dampier, Woodes, Rogers, Schovten, Roggewin, Lord 
 Anson, Byron, Carteret, Wallis, Bougainville, Cook, King, Clerk, Vancouver, and many 
 others. 
 
 381. These navigators, by sailing in a westerly direction, 
 allowance being made for promontories, &c., arrived at the coun- 
 try they sailed from. Hence the Earth must be either cylindri- 
 cal or globular. It cannot be cylindrical, because, if so, the 
 meridian distances would all be equal to each other, which is 
 
 * Magellan sailed from Seville, in Spain, August 10, 1519, in the ship called the Victory, 
 accompanied by four other vessels. In April, 1521, he was killed in a skirmish with the 
 natives, at the island of Sehu, or Zfbu, sometimes called Matan, one of the Philippines. 
 One of his vessels, however, arrived at St. Lucar, near Seville, September 7, 1522. 
 
 880. What second proof stated ? Who first sailed around the world? Who next? 
 081. In what direction did they s.i'l? How did these voyages prove the earth to he 
 
194 
 
 ASTRONOMY. 
 
 contrary to observation. The figure of the Earth is, therefore, 
 spherical. 
 
 382. The convexity of the Earth, north and south, is proved 
 by the variation in the altitude of the pole, and of the circum- 
 polar stars ; this is found uniformly to increase as we approach 
 them, and to diminish as we recede from them. 
 
 LATITUDE FOUND BY THB NORTH STAR. 
 
 Suppose an observer standing 
 upon the Earth, and viewing the 
 pole star from the 46 of North 
 latitude; it would, of course, 
 appear elevated 46 above hia 
 visible horizon. But let him 
 recede southward, and as he 
 passed over a degree of latitude, 
 the pole star would settle one 
 degree towards the horizon, or 
 more properly, his northern 
 horizon would be elevated one 
 degree towards the pole star, 
 till at length, as he crossed the 
 equator, the North star wouk" 
 sink below the horizon, and 
 become invisible. Whence wo X 
 derive the general rule, that 
 the alUtude of one pole, or the 
 depression of Vie other, at any 
 flaee on the Earth's wrface, is equal to the latitude of that place. 
 
 383. The form of the Earth's shadow, as seen upon the Moon 
 ;n an eclipse, indicates the globular figure of the Earth, and the 
 consequent convexity of its surface. 
 
 FOKM OF THE EARTH'S SHADOW. 
 
 382. What further proof have we that the earth Is &pherical? What rule 
 ,;poti this phenomenon ? 3S3. What other evidence that the earth is a globe 
 What remarks respecting the curvature of the earth's surface? What rules laid down 
 fcased upon this curvature? 
 
THE PRIMARY PLANETS- 
 
 'HE EARTH. 
 
 19f> 
 
 \Vcre the Earth a cube as shown at A, or in the form of a. prism, as represented at B, 
 her shadow would be more or less cubical or prismatic, as seen in the cut ; but instead 
 of this, it is convex on all sides, as represented at C, plainly indicating the convexity of 
 the Earth by which it is caused. , 
 
 The curvature of the Earth for one milt is 8 inches ; and this curvature increases with 
 the square of the distance. From this general law it will be easy to calculate the distance 
 at which any object whose height is given, may be seen, or to determine the height of an 
 object when the distance is known. 
 
 1st. To find the height of the object when the distance is given. 
 
 RULE. Find the square of Hie distance in miles, and take two-thirds of that number 
 
 for the height in feet. 
 
 low high must the eye of an observer be raised, to see the surface of the 
 ocean at the distance of three miles? Ann. The square of 3 ft. is 9 ft., and % of 9 ft. is 
 6 ft. Ex. 2. Suppose a person can just see the top of a spire over an extended plain of 
 ten miles, how high is the steeple ? Ans. The square of 10 is 100, and % of 100 is 
 66 % feet. 
 
 2. To find the distance when the height is given. 
 
 RULE. Increase the height in feet one-half, and extract tlie square root, for the dis 
 tance in miles. 
 
 Ex. 1. How far can a person see the surface of a plain, whose eye is elevated six 
 feet above it? Ans. 6, increased by half, is 9, and the square root of 9 is 3 : the distance 
 is then 3 miles. Ex. 2. To what distance can a person see a lighthouse whose height 
 is 96 feet from the level of the ocean ? Ans. 96 increased by its half, is 144, and the 
 square root of 144, is 12; the distance is therefore 12 miles. 
 
 3. To find the curvature of the Earth when it exceeds a mile. 
 RULE. Multiply the square of the distance by .000126. 
 
 ' 384. Although it appears from the preceding facts, that the 
 Earth is spherical, yet it is not a perfect sphere. If it were, the 
 length of the degrees of latitude, from the equator to the poles, 
 would be uniformly the same ; but it has been found, by the 
 most careful measurement, that as we go from the equator 
 towards the poles, the length increases with the latitude. 
 
 These measurements have been made by the most eminent mathematicians of different 
 countries, and in various places, from the equator to the arctic circle. They have found 
 that a degree of latitude at the arctic circle was mint-sixteenths of a mile longer than a 
 degree at the equator, and that the ratio of increase for the intermediate degrees was 
 nearly as the squares of the sines of the latitude. Thus the theory of Sir Isaac Newton 
 was confirmed, that the body of the Earth was more rounded and convex between the 
 tropics, but considerably flattened towards the poles. 
 
 Places of 
 Observation. 
 
 Latitude. 
 
 Length of a degree in 
 English miles. 
 
 Observers. 
 
 Pern 
 
 Pennsylvania 
 Italy 
 France 
 England 
 Sweden 
 
 Equator. 
 39 12' N. 
 43 01 
 46 
 51 29 54' 
 66 20 10 
 
 68.T32 
 6S.896 
 68.998 
 69.054 
 69.146 
 69.292 
 
 Bouguer, 
 Mason and Dixon, 
 Boscovich and Lemaire, 
 Delambre and Mechain, 
 Mudge, 
 Swamberg. 
 
 385. -These measurements prove the Earth to be an oblate 
 spheioid, whose longest or equatorial diameter is 7926 miles, and 
 polar diameter, 7899 miles. The mean diameter is, therefore, 
 about 7912, and their difference 27 miles. The French Acade- 
 
 884. But is the earth a sphere? What proof to the contrary? 885. What, then, is 
 hs earth's real figure ? What difference in her polar and equatorial diameters? Waut 
 demonstration that the earth is not an exact sphere ? 
 
196 ASTRONOMY. 
 
 my have determined that the mean diameter of the Earth, from 
 the 45th degree of north latitude, to the opposite degree of 
 south latitude, is accurately 7912 mifes. 
 
 If the Earth were an exact sphere, its diameter might bo 
 determined by its curvature, from a single measurement. Thus, 
 in the adjoining figure, we have A B equal to 1 mile, and B D 
 equal to 8 inches, to find A E, or B E, which does not sensibly 
 
 / / \ differ from A E, since B D is only 8 inches. Now it is a propo- 
 
 ' * si^ion of Euclid (B. 3, prop. 36), that, when from a point with- 
 out a circle, two lines be drawn, one cutting and the other 
 touching it, the touching line (B A) is a mean proportional be- 
 tween the cutting line (B E) and that part of it (B D) without 
 the circle. 
 
 BD: BA: : BEorAE very nearly. 
 That is, 1 mile being equal to 63,360 inches, 
 
 8 : 63,360 : : 1 : 7,920. miles. 
 This is very nearly what the most elaborate calculations make the Earth's equatorial 
 dia meter. 
 
 386. The Earth, considered as a planet, occupies a favored 
 rank in the Solar System. It pleased the All-wise Creator to 
 assign its position among the heavenly bodies, where nearly all 
 the sister planets are visible to the naked eye. It is situated 
 next to Venus, and is the third planet from the Sun. 
 
 To the scholar who for the first time takes up a book on astronomy, it will no doubt 
 seem strange to find the Earth classed with the heavenly bodies. For what can appear 
 more unlike, than the Earth, with her vast and seemingly immeasurable extent, and the 
 stars, which appear but as points? The Earth is dark and opaque, the celestial bodies 
 are brilliant. We perceive in it no motion ; while in them we observe a continual change 
 of place, as we view them at different hours of the day or night, or at different seasons 
 of the year. 
 
 387.- It moves round the Sun from west to east, in 365 days, 
 5 hours, 48 minutes, and 48 seconds ; and turns the same way, 
 on its axis, in 23 hours, 56 minutes, and 4 seconds. The former 
 is called its annual motion, and causes the vicissitudes of the 
 seasons. The latter is called its diurnal motion, and produces 
 the succession of day and night. 
 
 The Earth's mean distance from the Sun is about 95,000,000 
 of miles. It consequently moves in its orbit at the mean rate of 
 68,000 miles an hour. Its equatorial diameter being 7926 miles, 
 it turns on its axis at the rate of 1040 miles an hour. 
 
 Thus, tho Earth on which we stand, and which has served for ages as the unshaken 
 foundation of the firmest structures, is every moment turning swiftly on its center, aru. 
 at the same time, moving onwards with great rapidity through the empty space. 
 
 This compound motion is to be understood of the wftole Earth, with all that it holds 
 within its substance, or sustains upon its surface of the solid mass beneath, of tho 
 ocean which flows around it, of the air that rests upon it. and of the clouds which float 
 above it in the air. 
 
 38G. What said of the position of the earth in the system ? What remark as to clasaf 
 Tying the earth as a planet? 387. State the time of the earth's revolution around thn 
 Bun? On her own axis? What are they called, respectively ? What is the earth'e 
 distance from the sun? Its mean rate of motion in its orbit? Hourly motion of 
 at the equator? What twofold motion there? Includes what? 
 
THE PRIMARY PLANETS THE EARTH. 197 
 
 388. That the Earth, in common with all the planets, revolves 
 around the Sun as a center, is a fact which rests upon the clear- 
 est demonstrations of philosophy. That it revolves, like them, 
 upon its own axis, is a truth which every rising and setting sun 
 illustrates, and which very many phenomena concur to establish. 
 Either the Earth moves around its axis every day, or tfie whole 
 universe moves around it in the same time. There is no third 
 opinion that can be formed on this point. Either the Earth 
 must revolve on its axis every twenty-four hours, to produce the 
 alternate succession of day arid night, or the Sun, Moon, planets, 
 comets, fixed stars, and the whole frame of the universe itself, 
 must move, around the Earth, in the same time. 
 
 389. To suppose the latter case to be the fact, would be to 
 cast a reflection on the wisdom of the Supreme Architect, whose 
 laws are universal harmony. As well might the beetle, that in 
 a moment turns on its ball, imagine the heavens and the earth 
 had made a revolution in the same instant. It is evident, that 
 in proportion to the distance of the celestial bodies from the 
 Earth, must, on this supposition, be the rapidity of their move- 
 ments. The Sun, then, would move at the rate of more than 
 400,000 miles in a minute ; the nearest stars, at the inconceiv- 
 able velocity of 1,400,000,000 of miles in a second; and the 
 most distant luminaries, with a degree of swiftness which no 
 numbers could express, and all this, to save the little globe we 
 tread upon, from turning safely on its axis, once in twenty-four 
 hours. 
 
 390. The idea of the heavens revolving about the Earth, is 
 encumbered with innumerable other difficulties. We will men- 
 tion only one more. It is estimated on good authority, that 
 there are visible, by means of glasses, no less than 100,000,000 
 of stars, scattered at all possible distances in the heavens above, 
 beneath, and around us. Now, is it in the least degree probable, 
 that the velocities of all these bodies should be so regulated, 
 that, though describing circles so very different in dimensions, 
 they should complete their revolutions in exactly the same time? 
 In short, there is no more reason to suppose that the heavens 
 revolve around the Earth, than there is to suppose that they 
 revolve around each of the other planets, separately, and at the 
 same time ; since the same apparent revolution is common to 
 them all, for they all appear to revolve upon their axis, in differ- 
 ent periods. 
 
 888. What two motions has the eirth? What proof of her diurnal revolution ? S3y. 
 \\liy not suppose the heavens revalve around us ? 3'JO. What further proof? 
 
198 ASTRONOMY. 
 
 391. The rotation of the Earth determines the length of the 
 day, and may be regarded as one of the most important ele- 
 ments in astronomical science. It serves as an universal measure 
 of time, and forms the standard of comparison for the revolu- 
 tions of the celestial bodies, for all ages, past and to come. 
 Theory and observation concur in proving, that among the innu- 
 merable vicissitudes that prevail throughout creation, the period 
 of the Earth's diurnal rotation is immutable. 
 
 SOLAR AND SIDEREAL TIME. 
 
 392. The Earth performs one complete revolution on its axis 
 in 23 hours, 56 minutes, and 4.09 seconds, of solar time. This 
 is called a sidereal day,- because, in that time, the stars -appear 
 to complete one revolution around the Earth. 
 
 But, as the Earth advances almost a degree eastward in its 
 orbit, in the time that it turns eastward around its axis, it is 
 plain that just one rotation never brings the same meridian 
 around from the Sun to the Sun again ; so that the Earth 
 requires as much more than one complete revolution on its axis 
 to complete a solar day, as it has gone forward in that time. 
 
 SOLAR AND SIDEREAL TIME. 
 
 Q SIDEREAL DAY 
 
 SOLAR ^T_ 
 
 L^. " SUN ON T3E ME.RIDIAN 
 
 To the man at A the Sun (S) is exactly on the meridian, 'or it is twelve o'clock, noon. 
 11i2 Earth passes on from B to D, and at the same time revolves on her axis. When she 
 reaches D, the man who has stood on the same meridian has made a complete revolution, 
 as determined by the star G (which was also on his meridian at twelve o'clock the day 
 before) ; but the Sun is now east of the meridian, and he must wait/ottr minutes for the 
 Earth to roll a little further eastward, and bring the Sun again over his north and south 
 line. If the Earth was not revolving around the Sun, her solar and sidereal days would 
 be the same ; but as U is, she has to perform a little more than one complete revolution 
 each solar day, to bring the Sun on the meridian. 
 
 393. It is obvious, therefore, that in every natural or solar 
 day, the Earth performs one complete revolution on its axis, and 
 the 365th part of another revolution. Consequently, in 36? 
 days, the Earth turns 366 times around its axis. And as every 
 
 391. What relaliuu ha the earth's diurnal revolution to time f What said of its regu- 
 larity? 892. What is tne time required for a complete revolution? Explain the differ- 
 ence between solar and sidereal time? 393. Is a solar day more than a complete 
 revolution of the earth on her axis? To what does this excess amount in a year? 
 
THE PRIMARY PLANETS THE EARTH. 199 
 
 revolution of the earth on its axis completes a sidereal day, 
 there must be 366 sidereal days in a year. And, generally, 
 since the rotation of any planet about its axis is the length of a 
 sidereal day at that planet, the number of sidereal days will 
 always exceed the number of solar days by one, let that number 
 be what it may, one revolution being always lost in the course 
 of an annual revolution. This difference between the sidereal 
 and solar days may be illustrated by referring to a watch or 
 clock. When both hands set out together, at 12 o'clock for 
 instance, the minute hand must travel more than a whole circle 
 before it will overtake the hour hand, that is, before they will 
 come into conjunction again. 
 
 394. In the same manner, if a man travel around the Earth 
 eastwardly, no matter in what time, he will reckon one day more, 
 on his arrival at the place whence he set out, than they do who 
 remain at rest ; while the man who travels around the Earth 
 westwardly will have one day less. From which it is manifest, 
 that if two persons start from the same place at the same time > 
 but go in contrary directions, the one traveling eastward and 
 the other westward, and each goes completely around the globe, 
 although they should both arrive again at the very same hour 
 at the same place from which they set out, yet they will disagree 
 two whole days in their reckoning. Should the day of their 
 return, to the man who traveled westwardly, be Monday, to 
 the man who travelled eastwardly, it would be Wednesday ; 
 while to those who remained at the place itself, it would be 
 Tuesday. 
 
 395. Nor is it necessary, in order to produce the gain or loss 
 of a day, that the journey be performed either on the equator, 
 or on any parallel of latitude : it is sufficient for the purpose, 
 that all the meridians of the Earth be passed through, eastward 
 'or westward. The time, also, occupied in the journey, is equally 
 unimportant ; the gain or loss of a day being the same, whether 
 the Earth be traveled around in 24 years, or in as many hours. 
 
 396. It is also evident, that if the Earth turned around its 
 axis but once in a year, and if the revolution was performed the 
 same way as its revolution around the Sun, there would be per- 
 petual day on one side of it, and perpetual night on the other. 
 
 Flence what general rule ? What illustration referred to? 894. What effect has tra- 
 veling east or west, upon time ? Hence what result? 395. Is it important that the sup- 
 posed journeys be performed in a short period? 896. How would it be if tl.e Eartl. 
 revolved oc >ier axis but once a year? 
 
200 ASTRONOMY. 
 
 Prom these facts the pupil will readily comprehend the principles involved in a curious 
 problem which appeared a few years ago. It was gravely reported by an American ship, 
 that, in sailing over the ocean, it chanced to find six Sundays in February. The /act 
 was insisted on, and a solution demanded. There is nothing absurd in this. The man 
 who truvels around the earth eastwardly, will see the Sun go down a little earlier every 
 succeeding day, than if he had remained at rest; or earlier than they do who live at the 
 place from which he set out. The faster he travels towards the rising sun, the sooner 
 will it appear above the horizon in the morning, and so much sooner will it set in the 
 evening. What he thus gains in time, will bear the same proportion to a solar day, as 
 the distance traveled does to the circumference of the Earth. As the globe is 360 degrees 
 in circumference, the Sun will appear to move over one twenty-fourth part of its surface, 
 or 14 every hour, which is 4 minutes to one degree. Consequently, the Sun will rise, 
 come to the meridian, and set, 4 minutes sooner, at a place 1" east of us, than it will 
 with us ; at the distance of 2 the Sun will rise and set 8 minutes sooner ; at the distance 
 of 3, 12 minutes sooner, and so on. 
 
 Now the man who travels one degree to the east, the first day will have the Sun on his 
 meridian 4 minutes sooner than we do. who are at rest ; and the second day 8 minutes 
 sooner, and on the third day 1U minutes sooner, and so on ; each successive day being 
 completed 4 minutes earlier than the preceding, until he arrives again at the place from 
 which he started : when this continual gain of 4 minutes a day will have amounted to a 
 whole day in advance of our time : he having seen the Sun rise and set once more than 
 we have. Consequently, the day on which he arrives at home, whatever day of the 
 week it may be, is one day in advance of ours, and he must needs live that day over 
 again, by calling the next day by the same name, in order to make the accounts 
 harmonize. 
 
 If this should be the last day of February in a bissextile year, it would also be the 
 name day of the week that the first was, and be six times repeated, and if it should 
 happen on Sunday, he would, under these circumstances, have six Sundays in February. 
 
 Again : whereas the man who travels at the rate of one degree to the east, will have 
 al! his days 4 minutes shorter than ours, so, on the contrary, the man who travels at the 
 same rate towards the west, will have all his days 4 minutes longer than ours. When he 
 has finished the circuit of the Earth, and arrived at the place from which he first set 
 out, he will have seen the Sun rise and set once less than we have. Consequently, the 
 day he gets home will be one day after the time at that place; for which reason, if he 
 arrives at home on Saturday, according to his own account, he -will have to call the next 
 day Monday ; Sunday having gone by before he reached home. Thus, on whatever day 
 of the week January should end, in common years, he would find the same day r^p^ated 
 only three times in February. If January ended on Sunday, he would, under these cir- 
 eumstances, find only tliree Sundays in February. 
 
 397. The Earth's motion about its axis being perfectly equable 
 and uniform in every part of its annual revolution, the sidereal 
 days are always of the same length, but the solar or natural days 
 vary very considerably at different times of the year. This varia- 
 tion is owing to two distinct causes, the inclination of the Earth's 
 axis to its orbit, and the inequality of its motion around the Sun. 
 From these two causes it is, that the time shown by a well-regu : 
 lated clock and that of a true sun-dial are scarcely ever the 
 same. The difference between them, which sometimes amounts 
 to 16^ minutes, is called the Equation of Time, or the equation 
 of solar days. 
 
 What curious facts accounted for T What supposition of a man traveling eastward 
 one degree a day? What effect upon the time of the Sun's passing the meridian? Upon 
 the length of his daj ? What change of name may it require ? 897. Are the solar 
 and sidereal days alik s uniform as to length ? Why do solar days vary in length? WUj 
 do not a dial and clock agree ? What is the Equation of Time ? 
 
THE PRIMARY PLANETS THE EARTH 
 
 201 
 
 EQUATION OP TIMB 
 
 The difference between N 
 
 nean and apparent time, 
 or, in other words, between 
 Equinoctial and Ecliptic 
 time, may be further shown 
 by this figure, which repre- 
 sents the circles of the 
 sphere Let it be first pre- 
 mised, that equinoctial time 
 is clock time ; and that 
 ecliptic time is solar or 
 apparent time. It appears 
 that from Aries to Cancer, 
 the Sun in the ecliptic comes 
 to the meridian before the 
 equinoctial Sun ; from Can- 
 cer to Libra, after it ; from 
 Libra to Capricorn before 
 it ; and from Capricorn to 
 Aries after it. If we notice 
 what months the Sun is in 
 these several quarters, we 
 shall find that from the 25th 
 of December to the 16th of 
 April, and from the 16th of 
 June to the 1st of Septem- 
 ber, the clock i faster than 
 the sun-dial ; and that, from 
 
 the 16th of April to the 16th of June, and from the 1st of September to the 25th of De- 
 the sun-dial is faster than the clock. 
 
 398. It is an universal fact, that, while none of the planets are 
 perfect spheres, none of their orbits are perfect circles. The 
 planets all revolve about the Sun, in ellipses of different degrees 
 of eccentricity ; having the Sun, not in the center of the ellipse, 
 but in one of its foci. 
 
 The figure A D B E is an ellipse. The line A B is 
 called the transverse axis, and the line drawn through 
 the middle of this line, and perpendicular to it, is the 
 conjugate axis. The point C, the middle of the trans- 
 verse axis, is the center of the ellipse. The points 
 P and f, equally distant from C, are called the foci. 
 C F, the distance from the center to one of the foci, 
 is called the eccentricity. The orbits of the planets 
 being ellipses, having the Sun in one of the foci, if 
 A D B E be the orbit of a planet, with the Sun in the 
 focus F, when the planet is at the point A, it will be in 
 its perihelion, or nearest the Sun ; and when at the 
 point B in ita aphelion, or at its greatest distance 
 from the Sun. The difference in these distances is 
 evidently equal to P f, that is, equal to twice the eccentricity of its orbit. In every revo- 
 lution, a planet passes through its perihelion and aphelion. The eccentricity jf the 
 Earth's orbit is about one and a half millions of miles ; hence she is 3,000,000 of miles 
 nearer the Sun in her perihelion, than in her aphelion. 
 
 Now as the Sun remains fixed in the lower focus of the Earth's orbit, it is easy to per- 
 ceive that a line, passing centrally through the Sun at right angles with the longer axis 
 of the orbit, will divide it into two unequal segments. Precisely thus it is divided by 
 the equinoctial. 
 
 399. That portion of the Earth's orbit which lies above the 
 
 898. What is the true form of the planets' orbits ? Why ic equinoctial time irregular? 
 899. How is the Earth'* orbit divided by the equinoctial ? 
 
'202 ASTRONOMY. 
 
 Sun, or north of the equinoctial, contains about 184 degrees ; 
 while that portion of it which lies below the Sun, or south of the 
 equinoctial, contains only 176 degrees. This fact shows why 
 the Sun continues about eight days longer on the north side of 
 the equator in summer, than it does on the south side in winter. 
 The exact calculation, for the year 1830, is as folio vs : 
 
 d. h. ra. d. h. m. 
 
 From the vernal equinox to the summer solstice, =92 21 19 I -too -11 -in 
 
 From the summer solstice to the autumnal equinox, = 93 14 1 | 
 
 From the autumnal equinox to the winter solstice, = 89 17 17 \ 17 Q 1S <, rt 
 
 From the winter solstice to the vernal equinox, =89 1 13 J 
 
 Difference in favor of the north side, = 7 16 49 
 
 The points of the Earth^s orbit which correspond to its greatest and least distances 
 
 from the Sun, are called, the former the Apogee, and the latter the Perigee; two Greek 
 
 words, the former of which signifies from the EariJi, and the latter about the Earth. 
 
 These points are also designated by the common name of Apsides. 
 
 400. The Earth being in its perihelion about the 1st of Jan- 
 uary, and in its aphelion the 1st of July; we are 3,000,000 of 
 miles nearer the Sun in winter than in midsummer. The reason 
 why we have not, as might be expected, the hottest weather 
 when the Earth is nearest the Sun, is, because the Sun, at that 
 time, having retreated to the southern tropic, shines so obliquely 
 on the northern hemisphere, that its rays have scarcely half the 
 effect of the summer Sun ; and continuing but a short time above 
 the horizon, less heat is accumulated by day than is dissipated 
 by night. 
 
 401. As the Earth performs its annual revolution around the 
 Sun, the position of its axis remains invariably the same ; always 
 pointing to the North Pole of the heavens, and always main- 
 taining the same inclination to its orbit. This seems to be pro- 
 videntially ordered for the benefit of mankind. If the axis of 
 the Earth always pointed to the center of its orbit, all external 
 objects would appear to whirl about our heads in an inexplicable 
 maze. Nothing would appear permanent. The mariner could 
 no longer direct his course by the stars, and every index in 
 nature would mislead us. 
 
 What phenomenon does this explain ? 400. When is the Earth in Its perihelion ? It 
 aphelion ? What difference in its distance from the Sun ? Why, then, have we not tho 
 Traraest weather in January ? 401. What said of the permanency of the Earth's axis? 
 How H-ould it be if either pole was toward the Sun* 
 
THE MOON HER DISTANCE, MOTIONS, PHASES. 203 
 
 CHAPTER IV. 
 
 THE MOON HEv DISTANCE, MOTIONS, PHASES, &o. 
 
 402. THERE is no object within the scope of astronomical 
 observation which affords greater variety of interesting investi- 
 gation than the various phases and motions of the Moon. From 
 them the astronomer ascertains the form of the Earth, the vicis- 
 situdes of the tides, the causes of eclipses and occupations, the 
 distance of the Sun, and, consequently, the magnitude of the 
 solar system. These phenomena, which are perfectly obvious to 
 the unassisted eye, served as a standard of measurement to all 
 nations, until the advancement of science taught them the advan- 
 tages of solar time. It is to these phenomena that the naviga- 
 tor is indebted for that precision of knowledge which guides him 
 with well-grounded confidence through the pathless ocean. 
 
 The Hebrews, the Greeks, the Romans, and, in general, all 
 the ancients, used to assemble at the time of new or full Moon, 
 to discharge the duties of piety and gratitude for Irer unwearied 
 attendance on the Earth, and all her manifold uses. 
 
 The philosophy of the changes of the Moon is illustrated by 
 the following cut : 
 
 PHILOSOPHY OF THE MOON'S CHANGES. 
 
 X"* FIRST pR. 
 
 >s 
 
 <er. >" 
 
 ^" V^ C$ 
 
 > ) 
 
 r>^J/ \ rxs"^^^--^"""*" 
 
 / / II 
 
 \ OM*-?"..^ 
 
 ? FOT.L 
 
 Ney --, 
 
 sC-O~~f|- 
 
 "ic"i^ f\.-\ 
 
 - A.^-^--1-. 
 
 \ \ ' 11 
 
 H / j 
 
 GIBBOOSJQ QJ 
 
 e. ^e- 
 
 -*c 
 
 x -c..^ 
 
 s 
 
 This cut represents the moon revolving eastward around the Earth. In the t/utsido 
 circle, she is represented as she would appear, if viewed from a direction at right anglea 
 with the plane of her orbit. The side toward the Sun is enlightened in every case, and 
 she appears like a half moon at every point. 
 
 402. What sail of the Moon's motions and phases? What learned from them? How 
 used anciently? How at the present time? How did the ancients observe the new au! 
 full moons? 
 
 9* 
 
204 ASTRONOMY. 
 
 The interior suit represents her as she appears when viewed from the earth. At A It io 
 New Moon ; and if seen at all so near the Sun, she would appear like a dark globe. At 
 B she would appear like a crescent, concave toward the east. At C, more of her enlight- 
 ened side is visible ; at D still more ; and at E the enlightened hemisphere is fully in 
 view. We then call her a Full Moon. From E around to A again, the dark portion 
 becomes more and more visible, as the luminous part goes out of view, till she comes to 
 her change at A. When at D and F the moon is said to be gibbous. 
 
 403. When the Moon, after having been in conjunction with 
 the Sun, emerges from his rays, she first appears in the evening, 
 a little after sunset, like a fine luminous crescent, with its convex 
 side towards the Sun. If we observe her the next evening, we 
 find her about 13 farther east of the Sun than on the preceding 
 evening, and her crescent of light sensibly augmented. Repeat- 
 ing these observations, we perceive that she departs farther and 
 farther from the Sun, as her enlightened surface comes more and 
 more into view, until she arrives at her first quarter, and comes 
 to the meridian at sunset. She has then finished half her course 
 from the new to the full, and half her enlightened hemisphere is 
 turned towards the Earth. 
 
 404. After her first quarter, she appears more and more gib- 
 bous, as she recedes farther and farther from the Sun, until she 
 has completed just half her revolution around the Earth, and is 
 seen rising in the east when the Sun is setting in the west. She 
 then presents her enlightened orb full to our view, and is said 
 to be in opposition; because she is then on the opposite side of 
 the Earth with respect to the Sun, 
 
 la the first half of her orbit she appears to pass over our 
 heads through the upper hemisphere ; she now descends below 
 the eastern horizon to pass through that part of her orbit which 
 lies in the lower hemisphere. 
 
 405. After her full she wanes through the same changes of 
 pearance as before, but in an inverted order ; and we see her in 
 the morning like a fine thread of light, a little west of the rising 
 Sun. For the next two or three days she is lost to our view, 
 rising and setting in conjunction with the Sun ; after which, she 
 passes over, by reason of her daily motion, to the east side of 
 the Sun, and we behold her again, a new Moon, as before. In 
 changing sides with the Sun, she changes also the direction of 
 her crescent. Before her conjunction it was turned to the east ; 
 it is now turned towards the west. These different appearances 
 of the Moon are called her phases. They prove that she shines 
 
 403. Explain the cause of the changes of the Moon ? 404. Row after her first quarter? 
 406. How after her full? What change in her crescent? What do the Moon's phasea 
 prove ? 
 
THE .ICON - HER MOTIONS, PHASES, ETC. 20i> 
 
 fKt by any light of her own ; if she did, being globular, wo 
 should always see her a round full orb like the Sun. 
 
 406. The Moon is a satellite to the Earth, about which she 
 revolves in an elliptical orbit, in 29 days, 12 hours, 44 minutes, 
 and 3 seconds ; the time which elapses between one new moon 
 and another. This is called her synodic revolution. Her revo- 
 lution from any fixed star to the same star again, is called her 
 periodic or sidereal revolution. It is accomplished in 27 days, 7 
 hours, 43 minutes, and 11 seconds ; but in this time, the Earth 
 has advanced nearly as many degrees in her orbit ; consequently, 
 the Moon, at the end of oce complete revolution, must go as 
 many degrees farther, before she will come again into *he same 
 position with respect to the Sun and the Earth. 
 
 SIDEREAL AMD SYNODIC REVOLUTIONS OP THK MOON. 
 
 \ 
 
 SUN AND MOON IN CONJUNCT ION- NEW MOON/ 
 
 A- 
 
 On the right, the earth is shown in her orbit, revolving around the sun, and the moon 
 In her orbit, revolving around the earth. At A, the sun and uioon are in conjunction, 
 or it is New Moon. As the earth passes from D to E, the moon passes around from A to 
 B, or the exact point in her orbit where she was 27^ days before. But she is still west 
 of the sun, and must pass on from B to C, or 1 day and 20 hours longer, before she can 
 again come in conjunction with him. This 1 day and 20 hours constitutes the difference 
 between a sidereal and a synodic revolution. 
 
 The student will perceive that the difference between a sidereal and synodic revolution 
 of the moon, like that between solar and sidereal time, is due to the same cause, namely, 
 the revolution of the earth around the sun. 
 
 407. Lying along the Moon's path, there are nine conspicu- 
 ous stars that are used by nautical men for determining their 
 longitude at sea, thence called nautical *tars. These stars are, 
 Arietes, Aldebaran, Pollux, Regulus, Spica Virginis, Antares, 
 Altaire, Fomalhaut, and Markab. 
 
 The true places of these stars, for every day in the year, are given in the Nautical 
 Vlmanac, a valuable work published annually by the English " Board of Admiralty," to 
 ^uide mariners in navigating the seas. They are usually published two or three years in 
 vdvance. for the benefit of long voyages 
 
 Let A in the cut represent Greenwich Observatory, near London. B is the Moon, and 
 C her apparent place among the distant stars, about 40* west of the star D. The ship-B, 
 Laving Greenwich time, as well as her own local time, sails from London westward ; 
 
 406. Form of the lunar orbit? Time of synodic revolution? Of sidereal revolution? 
 Wl-at difierence ? 407. What are the nautical stars? Can you explain how longitude 
 i ascertained by them? 
 
^06 
 
 ASTRONOMY. 
 
 but on observing the Moon when, by Greenwich 
 time, she ought to be at C, she is found to be at F, or 
 only about 20 west of the star D. It is, therefore, 
 obvious that the ship is west of Greenwich, as the 
 Moon appears east of her Greenwich place. Prom 
 this difference between her place as laid down in the 
 tables, and her observed place, as referred to cer- 
 tain prominent stars, the mariner determines ho;v 
 far he is east or west of the meridian of Greenwich. 
 The Moon's geocentric place (or place as viewed 
 from the center of the Earth) may be given instead 
 of her Greenwich place, and the same conclusions 
 arrived at. In either case, this is called the liwar 
 method of determining the longitude. It is also ascer- 
 tained by simple comparison of local and standard 
 time, that a man, says Sir John Herschel, by merely 
 measuring the Moon's apparent distance from a star, 
 with a little portable instrument held in his hand, 
 and applied to his eye, even with so unstable a foot- 
 ing as the deck of a ship, shall say positively wilhin 
 five miles where he is, on a boundless ocean, cannot 
 but appear to persons ignorant of physical astronomy 
 an approach to the miraculous. And yet, says he 
 the alternatives of life and death, wealth and ruin 
 are daily and hourly staked, with perfect confidence 
 on these marvellous computations. 
 
 408. The Moon is the nearest of all the heavenly bodies, being 
 about thirty times the diameter of the Earth, or 239,000 miles, 
 distant from us. Her mean daily motion in her orbit is nearly 
 fourteen times as great as the Earth's ; since she not only accom- 
 panies the Earth around the Sun every year, but, in the mean 
 time, performs nearly thirteen revolutions about the Earth. 
 
 Although the apparent motion of the Moon in her orbit is greater than that of any 
 other heavenly body, since she passes over, at a mean rate, no less than 18 10' 35" in a 
 day ; yet this is to be understood as angular motion, motion in a small orbit and 
 therefore embracing a great number of degrees, and but comparatively few miles. 
 
 409. The point in the Moon's orbit 
 nearest the Earth is called Perigee, from 
 the Greek peri, about, and ge, the earth. 
 The point most distant is called Apogee, 
 from apo, from, and ge, the earth. These 
 two points are also called the apsides 
 of her orbit ; and a line joining then^ 
 the line of the apsides. 
 
 See the Moon in apogee and perigee in the cut. Tbo 
 singular of apsides is apsis. 
 
 410. The line of the apsides of the 
 Moon's orbit is not fixed in the ecliptic, 
 but revolves slowly around the ecliptic, 
 
 408. The Moon's distance? Daily motion in orbit? How many degrees? 409 
 Perigee and Apogee ? Derivation ? What other name for these two points ? What, it 
 the line of the apsides ? 410. Is this line stationary? What motion? Its period cf 
 roTolut'on ? 
 
THE MOON HER MOTIONS, PHASES, ETC. 207 
 
 from west to east, in the period MOTION ov TnB AP8n)E8 - 
 
 of about nine years. 
 
 In the adjoining cut, an attempt is made to 
 represent this motion. At A, the line of the 
 apsides points directly to the right and left ; 
 but at B, C, and D, it is seen changing its 
 direction, till at E the change is very percep- 
 tible when compared with A. But the same 
 ratio of change continues ; and at the end of 
 a year, when the Earth reaches A again, the 
 line of the apsides is found to have revolved 
 eastward to the dotted line I K, or about 40. 
 In nine years the aphelion point near A will 
 have made a complete revolution, and return- 
 ed to its original position. 
 
 411. The line of the Moon's 
 nodes is also in revolution ; but 
 
 it retrogrades or falls back westward, making the circuit of the 
 ecliptic once in about nineteen years. 
 
 4 1 2. Though her orbit is an ellipse, B ^. m '.-- *-. 
 with respect to the Earth, it is, in ....;'-"* 
 reality, an irregular curve, always .*< 
 
 concave toward the. Sun, and crossing .J 
 the Earth's orbit every 13 nearly. f || 
 
 If the Earth stood still in her orbit, the Moon Xj.., 
 would describe just such a path in the ecliptic as f\ 
 she describes with respect to the Earth. ^ ^ 
 
 If the Earth moved but slowly on her way, the 
 Moon would actually retrograde on the ecliptic at 
 tho time of her change, and would cross her own , * 
 path at every revolution, as shown in the adjoin- ^ 
 
 ing figure. But as the Earth advances some 
 
 46,000,000 of miles, or near 100 times the diameter ''-*'' * 
 
 of the Moon's orbit, during a single lunation, it is 
 
 evident that the Moon's orbit never can return into itself, or retrograde, as here repre- 
 sented. 
 
 That the lunar orbit is always concave toward the Sun, may be demonstrated by the 
 above diagram. 
 
 THE MOON'S ORBIT ALWAYS CONCAVE TOWARD THB SUN. 
 
 " "" 
 
 
 Let the upper curve line A B represent an arc of the Earth's orbit, equal tc that 
 passed through by the Earth during half a lunation. Now the radius and arc being 
 known, it is found that the chord A B must pass more than 400,000 miles within tho 
 Earth. But as the Moon departs only 240,000 from the Earth, as shown in the figure, it 
 follows that she must describe the curve denoted by the middle line, which is concave 
 toward the Sun. 
 
 This subject may be still further illustrated by the following cut : 
 
 411. How with the line of the Moon's nodes? 412. What is the actual form of tho 
 Moon's orbit? How if the Earth stood still ? Row if she moved but slowly? How is 
 ,c Moon's orbit demonstrated to be always concave towards the Sun ? 
 
208 
 
 ASTRONOMY. 
 
 TH* MOON'S PATH DURING A COMPLETE LCNATIOW. 
 C B 
 
 Bere the plain line represents the Earth's orbit, and the dotted one that of the Moon. Ai 
 A. ihe Moon crosses the Earth's track 240,000 miles behind her. She gains on the Earth, 
 till in seven days she passes her at B as a Full Moon. Continuing to gain on the Earth, 
 Bhe crosses her orbit at C, 240,000 miles ahead of her, being then at her Third Qiuiner. 
 From this point the Earth gains upon the Moon, till seven days afterward she overtakes 
 her at D as a New Moon. From D to E the Earth continues to gain, till at E the Moon 
 crosses 240,000 behind the Earth, as she had done four weeks before at A. Thus the 
 Moon winds her way along, first within and then without the Earth ; always gaining upon 
 us when outside of our orbit, and falling behind us when within it. 
 
 The small circles in the cut represent the Moon's orbit with respect to the Earth, which 
 is as regular to us as if the Earth had no revolution around the Sun. 
 
 413. The moon never retrogrades on the ecliptic, or returns 
 into her own path again ;' but is always advancing with the 
 Earth, at the rate of not less than 65,700 miles per hour. 
 
 KOON'S PATH. The Moon's orbitual velocity, with respect to the 
 
 Earth, is about 2300 miles pr hour. When outside 
 the Earth, as at B, in the last figure, she gain* 28- *> 
 miles per hour, which added to the Earth's velocitj 
 would give 70,300 miles as the hourly velocity of the 
 Moon. When within the Earth's orbit, as at D, she 
 loses 2300 miles per hour, which, abstracted from 
 68,000 miles (the Earth's hourly velocity), would leave 
 65,700 miles as the slowest motion of the Moon iu 
 space, even when she is falling behind the Earth. 
 
 Could we look down perpendicularly upon the eclip- 
 tic, and see the paths of the Earth and Moon, we should 
 see the latter pursuing her serpentine course, first 
 within and then outside our globe, somewhat as repre- 
 sented by the dotted line in the annexed figure. Her 
 path, however, would be concave toward the Sun, as. 
 shown on the preceding page, and not convex, as we 
 were obliged to represent it here in so small a diagram. 
 
 414. In her journey ings eastward, the Moon often seems tc 
 
 run over and obscure the distant planets 
 and stars. This phenomenon is called 
 an occultation. 
 
 The adjoining cut represents the new Moon as ju?< 
 about to obscure a distant star, by passing between 
 us and it. In 1850, she occulted Jupiter for three 
 revolutions in succession viz., Jan. 30th, Feb. 27th, 
 and March 26th. Through a telescope, the Moon \? 
 seen to be constantly obscuring stars that are invisi 
 ble to the naked eye. They disappear behind the 
 Moon's eastern limb, and in a short time reappear 
 from behind her western ; thus distinctlj exhibiting 
 her eastward motion. 
 
 413. Does she ever retrog-ade on the ecliptic? What 13 her slowest motion? How 
 Jemonstrated ? 414. Whui is an occultation f Remarks respecting this phenomenon 7 
 
THE MOOI* HER MOTIONS, PHASES, ETC. 
 
 209 
 
 MOON'S REVOLUTION. 
 
 415. The Moon revolves once on her axis exactly in the time 
 that she performs her revolution around the Earth. This is evi- 
 dent from Ler always presenting the same side to the Earth ; 
 for if she had no rotation upon an axis, every part of her surface 
 would be presented to a spectator on the Earth, in the course 
 of her synodical revolution. It fol- 
 lows, then, that there is but one day 
 
 and night in her year, containing, 
 both together, 29 days, 12 hours, 
 44 minutes, and 3 seconds. 
 
 Suppose a monument erected upon the Moon's 
 surface, so as to point toward the Earth at New 
 Afoon, as represented at A. From the Earth it 
 would appear in the Moon's center. Now if the 
 Moon so revolve upon her axis, in the direction of 
 the arrows, as tu keep the pillar pointing directly 
 toward the Earth, as shown at A, B, C, and D, and 
 the intermediate points, she must make just one 
 revolution on her axis during her periodic revolu- 
 tion. At A, the pillar points from the Sun, and at 
 C toward him : showing that, in going half-way 
 round the Earth, she has performed half a revolu- 
 tion upon her axis. 
 
 416. Though the Moon always presents nearly the same hemi- 
 sphere toward the Earth, it is not always precisely the same. 
 Owing to the ellipticity of her orbit, and the consequent 
 inequality of her angular velocity, she appears to roll a little on 
 her axis", first one way and then the other thus alternately 
 revealing and hiding new territory, 
 
 as it were, on her eastern and west- ^^.^ 
 
 ern limbs. This rolling motion east ...- t) 
 
 and west is called her lilration in X B 
 
 Longitude. fix. 
 
 J 
 
 / 
 
 MOON'S LIBRATION. 
 
 >' 
 
 The accompanying cut will illustrate the subject 
 of the Moon's Vibrations in longitude. - 
 
 From A around to C, the angular motion is 
 slmcer than the average, and the diurnal motion 
 gains upon it, so that the pillar points west of the 
 Earth, and we see more of the eastern limb of the 
 moon. 
 
 From C to A, again, the Moon advances faster 
 than a mean rate, and gains upon the diurnal 
 revolution ; go that the pillar points east of the 
 Earth, and we see more of the Moon's western 
 limb. Thus she seems *r librate or roll, first 
 o ie way and then ti.<; other, during every periodic 
 re volution. 
 
 At B, we see most of her eastern limb ; and at D, most of her western. 
 
 417. The axis of the Moon is inclined to the plane of her 
 orbit only about one and a half degrees ( 1 30' 1 0.8*}. But this 
 
 415. How often does the Moon revolve on her axis? How is it known ? What follo-Td 
 from this fact? 416. What are the Moon's librations? In Lontfiiu.de? 4lT. In 
 
210 ASTRONOMY. 
 
 slight inclination enables us to see first one pole and then the 
 other, in her revolution around the Earth. These slight rolling 
 motions are called her librations in Latitude 
 
 As tne inclination of the Earth's axis brings first one pole and then the other toward the 
 Run, and produces the seasons, so the inclination of the Moon's axis brings first one polo 
 and then the other in view from the Earth. But as her inclination ia only 1J$, tho 
 libration in latitude is very slight. 
 
 418. "As the Moon turns on her axis only as she moves around 
 the Earth, it is plain that the inhabitants of one half of the 
 lunar world are totally deprived of the sight of the Earth, unless 
 they travel to the opposite hemisphere. This we may presume 
 they will do, were it only to view so sublime a spectacle ; for it 
 is certain that from the Moon the Earth appears ten times larger 
 than any other body in the universe. 
 
 419. As the Moon enlightens the Earth, by reflecting the light 
 of the Sun, so likewise the Earth illuminates the Moon, exhibit- 
 ing to her the same phases that she does to us, only in a con- 
 trary order. And, as the surface of the Earth is 13 times as 
 large as the surface of the Moon, the Earth, when full to the 
 Moon, will appear 13 times as large as the full Moon does to us. 
 That side of the Moon, therefore, which is towards the Earth, 
 may be said to have no darkness at all, the Earth constantly 
 shining upon it with extraordinary splendor when the Sun is 
 absent ; it therefore enjoys successively two weeks of illumina- 
 tion from the Sun, and two weeks of earth-light from the Earth. 
 The other side of the Moon has alternately a fortnight's light, 
 and a fortnight's darkness. 
 
 420. As the Earth revolves on its axis, the several continents, 
 seas, and islands, appear to the lunar inhabitants like so many 
 spots of different forms and brightness, alternately moving over 
 its surface, being more or less brilliant, as they are seen through 
 intervening clouds. By these spots, the lunarians can not only 
 determine the period of the Earth's rotation, just as we do that 
 of the Sun, but they may also find the longitude of their places, 
 as we find the latitude of ours. 
 
 421. As the full Moon always happens when the Moon is 
 directly opposite the Sun, all the full moon;: in our winter, must 
 happen when the Moon is on the north side of tne equinoctial, 
 
 418. Can all the Lunarians see the Earth? How large must she appear from tht- 
 Moon? 419. What said of her light and phases ? How, then, are the two hemispheres of 
 the Moon enlightened? 420. How must the Earth appear to the Lunarians, and what 
 , may they infer from the motion of the spots seen on her surface? 421. W'.ere is the 
 Moon at the full in winter? In summer? Why? What result as to moonlighf at the 
 poles ? 
 
THE MOON HER MOTIONS, PHASES, ETC. 211 
 
 because then the Sun is on the south side of it ; consequently, at 
 the north pole of the Earth, there will be a fortnight's moon- 
 light and a fortnight's darkness by turns, for a period of six 
 months, and the same will be the fact during the Sun's absence 
 the other six months, at the south pole. 
 
 422. The plane of the Moon's orbit is very near that of the 
 ecliptic. It departs from the latter only about 5 (5 8' 48 W .) 
 
 INCLINATION OP THB MOON'S ORBIT TO THE PLANB OF THI ECLIPTIC. 
 
 Let the line A B represent the plane of the Earth's orbit, and the line joining the Moon 
 at C and D would represent the inclination of the Moon's orbit to that of the Earth. At 
 C the Moon would be within the Earth's orbit, and at D exterior to it ; and it would bo 
 Full Moon at D, and New Moon at C. 
 
 423. The Moon's axis being inclined only about 1|- to her 
 orbit, she can have no sensible diversity of seasons ; from which 
 we may infer, that her atmosphere is mild and uniform. The 
 quantity of light which we derive from the Moon when full, is at 
 least 300,000 times less than that of the Sun. 
 
 This is Monsieur Bouquer's inference, from his experiments, as stated by La Place, in 
 hii work, p. 42. The result of Dr. Wollaston's computations was different. Professor 
 Leslie makes the light of the Moon 150,000 times less than that of the Sun ; it was for- 
 merly reckoned 100,000 times less. 
 
 424. The Moon, though apparently as large as the Sun, is the 
 smallest of all the heavenly bodies tmit are visible to the naked 
 eye. Her diameter is but 2162 miles ; consequently her surface 
 is 13 times less than that of the Earth, and her bulk 49 times 
 less. It would require 70,000,000 of such bodies to equal the 
 volume of the Sun. The reason why she appears as large as the 
 Sun, when, in truth, she is so much less, is because she is 400 
 times nearer to us than the Sun. 
 
 425. When viewed through a good telescope, the Moon pre- 
 sents a most wonderful and interesting aspect. Besides the 
 large dark spots, which are visible to the naked eye, we perceive 
 extensive valleys, shelving rocks, and long ridges of elevated 
 mountains, projecting their shadows on the plains below. Single 
 mountains occasionally rise to a great height, while circular hol- 
 lows more than three miles deep, seem excavated in the plains. 
 
 422. How is the Moon's orbit situated with respect to the ecliptic ? 423. What is 
 the inclination of the Moon's axis, and what effect has it on her seasons and atmosphere ? 
 What is the amount of light derived from the Moon as compared with the Suu, and ib 
 there any difference of opinion on this point? 424. What said of the apparent and 
 real diameters of the Moon? Compared with the Earth? The Sun? Why, then, 
 appear as large as he does T 425. How does she appear through a telescope V 
 
212 
 
 ASTRONOMY 
 
 TELESCOPIC VIEW OF THIS MOON. Specimens of these shadows may 
 
 be seen in the cut, projecting to 
 the left. Bright points of light, or, 
 in other words, the illuminated 
 tops of mountains, may also be 
 seen near the terminator, in the 
 dark portion. The writer has often 
 watched them, and sen them en- 
 large more and more, as the Sun 
 arose upon the side of the Moon 
 toward us, and enlightened the 
 sides of her mountains. 
 
 The shadows are always pro- 
 jected in a direction opposite the 
 Sun, or towards the dark side 
 of the moon ; and as her eastern 
 limb is dark from the change to the 
 full, and her western from the lull 
 to the change, of course the direc- 
 tion of the shadow* must be re- 
 versed. 
 
 Suppose a person stationed at a 
 distance directly over the Andes. 
 Before the Sun arose, he would see 
 the tallest peaks enlightened ; and 
 as he arose, the long shadows of 
 the mountains would extend to tne 
 west. At noon, however, little or no shadow would be visible ; but at sunset, they would 
 again be s"een stretching away to the east. This is precisely the change that ic 
 seen to take place with the lunar shadows, except that the time required is a lunar day, 
 equal to about 15 of our days, instead of one of our days of 12 hours. 
 
 426. The Moon's mountain scenery bears a striking resem- 
 blance to the towering sublimity and terrific ruggedness of the 
 Alpine regions, or of the Apennines, after which some of her 
 mountains have been named, and of the Cordilleras of our own 
 continent. Huge masses of rock rising precipitously from the 
 plains, lift their peaked summits to an immense height in the air, 
 while shapeless crags hang over their projecting sides, and seem 
 on the eve of being precipitated into the tremendous chasm 
 below. 
 
 Around the base of these frightful eminences, are strewed 
 numerous loose and unconnected fragments, which time seems to 
 have detached from their parent mass ; and when we examine 
 the rents and ravines which accompany the overhanging cliffs, 
 the beholder expects every moment that they are to be torn 
 from their base, and that the process of destructive separation 
 which he had only contemplated in its effects, is atfout to be 
 exhibited before him in all its reality. 
 
 427. The range of mountains called the Apennines, which 
 traverses a portion of the Moon's disc from northeast to south- 
 west, and of which some parts are visible to the naked eye, rises 
 
 426. What said of the Moon's mountain scenery? 
 T!cular ? 
 
 427. Of the Apennines in nc,j 
 
THE MOON HER MOTIONS, PHASES, ETC 213 
 
 with a precipitous and craggy front from the level of the Mare 
 Imbrium, or Sea of Showers. In this extensive range are several 
 ridges whose summits have a perpendicular elevation of four 
 miles, and more ; and though they often descend to a much 
 lower level, they present an inaccessible barrier on the northeast, 
 while on the southwest they sink in gentle declivity to the 
 plains. 
 
 428. There is one remarkable feature in the Moon's surface 
 which bears no analogy to anything observable on the Earth. 
 This is the circular cavities which appear in every part of her 
 disc. Some of these immense caverns are nearly four miles deep, 
 ana forty miles in diameter. They are the most numerous in the 
 southwestern part. As they reflect the Sun's rays more 
 copiously, they render this part of her surface more brilliant 
 than any other. They present to us nearly the same appearance 
 as our Earth might be supposed to present to the Moon if all 
 our great lakes and seas were dried up. 
 
 429. The number of remarkable spots on the Moon, whose 
 latitude and longitude have been accurately determined, exceeds 
 200. The number of seas and lakes, as they were formerly con- 
 sidered, whose length and breadth are known, is between 20 and 
 30 ; while the number of peaks and mountains, whose perpen- 
 dicular elevation varies from a fourth of a mile to five miles in 
 height, and whose bases are from one to seventy miles in length 
 is not less than one hundred and fifty. 
 
 Graphical views of these natural appearances, accompanied with minute and familiar 
 descriptions, constitute what is called Selenography, from two Greek words, which mean 
 the same thing in regard to the Moon, as Geography does in regard to the Earth. 
 
 430. An idea of some of these scenes may be formed by con- 
 ceiving a plane of about 100 miles in circumference, encircled by 
 a range of mountains, of various forms, three miles in perpen- 
 dicular height, and having a mountain near the center, whose 
 top reaches a mile and a half above the level of the plain. From 
 the top of this central mountain, the whole plain, with all its 
 scenery, would be distinctly visible, and the view would be 
 bounded only by a lofty amphitheatre of mountains, rearing their 
 summits to the sky. 
 
 431. The bright spots of the Moon are the mountainous 
 regions ; while* the dark spots are the plains, or more level parts 
 of her surface. There may be rivers or small lakes on this 
 
 428. What remarkable feature of the Moon's surface noticed ? 429. What numboi 
 f remark-able spots ? Of " seas or lakes ? " Of mountains ? What is Selenography ? 
 C\ Uc-v uonceive jurtly of the lunar scenery? 481. What are the brightest spota oo 
 
214 ASTRONOMY. 
 
 planet ; but it is generally thought, by astronomers of the presen* 
 "day, that there are no seas or large collections of water, as was 
 formerly supposed. Some of these mountains and deep valley? 
 are visible to the naked eye ; and many more are visible through 
 a telescope of but moderate powers. 
 
 432. A telescope which magnifies only 100 times will show a 
 spot on the Moon's surface, whose diameter is 1223 yards ; ana 
 one which magnifies a thousand times, will enable us to perceive 
 any enlightened object on her surface whose dimensions are only 
 122 yards, which does not much exceed the dimensions of some 
 of our public edifices, as for instance, the Capitol at Washington, 
 or St. Paul's Cathedral. Some years since, Professor Frauen- 
 hofer, of Munich, announced that he had discovered a lunar 
 edifice, resembling a fortification, together with several lines of 
 road. The celebrated astronomer Schroeter, conjectures the 
 existence of a great city on the east side of the Moon, a little 
 north of her equator, an extensive canal in another place, and 
 fields of vegetation ir another. 
 
 CHAPTER Y. 
 
 SOLAR AND LUNAR ECLIPSES. 
 
 483. OF all the phenomena of the heavens, there are none 
 which engage the attention of mankind more than eclipses of the 
 Sun and Moon ; and to those who are unacquainted with astro- 
 nomy, nothing appears more wonderful than the accuracy with 
 which they can be predicted. In the early ages of antiquity, 
 they were regarded as alarming deviations from the established 
 laws of nature, presaging great public calamities, and other 
 tokens of the divine displeasure. 
 
 In China, the prediction and observance of eclipses are made a matter of state policy, 
 in order to operate upon the fears of the ignorant, and impose on them a superstitioun 
 regard for the occult wisdom of their rulers. In Mexico, the natives fast and afflict ttiem- 
 selves, during eclipses, under an apprehension that the Great Spirits in deep sufferance. 
 Some of the northern tribes of Indians have imagined that the Moon had been wounded 
 in a quarrel ; and others, that she was about to be swallowed by a hpge fish. 
 
 the Moon's surface? The dark ones? 432. How small objects maybe seen ou tho 
 Moon's surface? What announcement by Frauenhofer? Conjecture of Srhroeter ( 
 488. Subject of Chapter V.? Remark respecting eclipses? How regarded by tic 
 ancients? In China? Mexico? By northern Indians? Anecdote of Columbus 9 
 
SOLAR AND LUNAR ECLIPSES. 215 
 
 It was by availing himself of these superstitious notions, that Columbus, when ship- 
 wrecked on the island of Jamaica, extricated himself and crew from a most embarrass- 
 ing condition. Being driven to great distress for want of provisions, and the natives 
 refusing him any assistance, when all hope seemed to be cut off, he bethought himself of 
 their superstition in regard to eclipses. Having assembled the principal men of the 
 island, he remonstrated against their inhumanity, as being offensive to the Great Spirit : 
 and told them that a great plague was even then ready to fall upon them, and as a token 
 of it, they would that night see the Moon hide her face in anger, and put on a dreadfully 
 dark and threatening aspect. This artifice had the desired effect; for the eclipse had no 
 nooner begun, than the frightened barbarians came running with all kinds of provisions, 
 and throwing themselves at the feet of Columbus, implored his forgiveness. Almagest, 
 vol. /., 55 c. v. 2. 
 
 434. An eclipse of the Sun takes place, when the dark body 
 of the Moon, passing directly between the Earth and the Sun, 
 intercepts his light. This can happen only at the instant of new 
 rnoon, or when the Moon is in conjunction ; for it is only then 
 that she passes between us and the Sun. 
 
 An eclipse of the Moon takes place when the dark body of 
 the Earth, coming between her and the Sun, intercepts his light, 
 and throws a shadow on the Moon. This can happen only at the 
 time of full moon, or when the Moon is in opposition ; for it is 
 only then that the Earth is between her and the Sun. 
 
 435. As every planet belonging to the solar system, both pri- 
 mary and secondary, derives i4s light from the Sun, it must cast 
 a shadow towards that part of the heavens which is opposite to 
 the Sun. If the Sun and planet were both of the same magni- 
 tude, the form of the shadow cast by the planej:, would be that 
 of a cylinder, and of the same diameter as the Sun or planet. 
 
 CYLINDRICAL SHADOW. 
 
 Here the Sun and planet are represented as of tlie same size, and the shadow of the 
 latter is in the form of a cylinder. 
 
 436. If the planet were larger than the Sun, the shadow would 
 continually diverge, and grow larger and larger ; but as the Sun 
 is much larger than any of the planets, the shadows which they 
 cast must converge to a point in the form of a cone, the length 
 of which will be proportional to the size and distance of the 
 planet from the Sun. 
 
 434. When do solar eclipses occur? Why only then? Lunar? Why only at full 
 moon ? 435. Do all the planets cast shadows ? Suppose the Sun and planet were of 
 the. same size, what would be the form of their shadows? 436. What if the planet waa 
 largest ? How as they are smaller than the Sun ? How is the length of the shadov 
 modified bj the distance of the planet from the Sun ? 
 
ASTRONOMY. 
 
 DIVERGING SHADOW. 
 
 In this cut, the opaque body is ttie larger, and the ^ i d e ^ rojected fr m lt dt9 * 
 point. 
 
 CONVERGING SHADOW. 
 
 Here the luminous body is the larger, and the shadow converges to a n^int, and t* IB 
 the form of a cone. 
 
 The opaque body being smaller than the luminous one, the length, of its shadow will o 
 modified by its distance, as in the following : 
 
 Here, also, the luminous body is the larger, and both precisely or the ff.me size as 1 
 the cut preceding ; but teing placed nearer each other, the shadow is shown to be cor 
 siderably shorter. 
 
 437. All the planets, both primaries and secondaries, cas 
 shadows in a direction opposite the Sun (see cut on i?ext page) 
 The form and length of these shadows depend upon the compare 
 tive magnitude of the Sun and planet, and their distance from 
 each other. If the Sun and a planet were of the same size, the 
 shadow of the planet would be in the form of a cylinder, what- 
 ever its distance. If the planet was larger than the Sun, the 
 shadow would diverge, as we proceed from the planet off into 
 space ; and the nearer the Sun, the more divergent the shadow 
 would be. But as the planets are all much smaller than the 
 Sun, the shadows all converge to a point, and take the form of a 
 cone; and the nearer' to the Sun, the shorter their shadows. 
 
 437. Why have the largest and most distant planets the longest shadows ? Do Any of 
 fce primary planets eclipse each other? 
 
SOLAR AND LUNAR ECLIPSES 
 
 217 
 
 SHADOWS OF THE PLANETS. 
 
 These principles are partly illus- 
 trated in the adjoining cut. The 
 planets nearest the Sun have com- 
 paratively short shadows, while those 
 more remote extend to a great dis- 
 tance. No primary, however, casts a 
 shadow long enough to reach the next 
 exterior planet. 
 
 The magnitude of the Sun is such, 
 that the shadow cast by each of the 
 primary planets always converges to 
 a point before it reaches any other 
 planet; so that not one of the pri- 
 mary planets can eclipse another. 
 The shadow of any planet which is 
 accompanied by Satellites, may, on 
 certain occasions, ec'ipse its satel- 
 lites ; but it is not long enough to 
 eclipse any other body. The shadow 
 of a satellite or Moon, may also, on 
 certain occasions, fall on the primary, 
 and eclipse it. 
 
 438. When the Sun is at his greatest distance from the Earth, 
 and the Moon at her least distance, her shadow is sufficiently 
 long to reach the Earth, and extend 19,000 miles beyond. 
 When tbe Sun is at his least distance from the Earth, and the 
 Moon at her greatest, her shadow will not reach the Earth's sur- 
 face by 20,000 miles. So that when the Sun and Moon are at 
 their mean distances, the cone of the Moon's shadow will termi- 
 nate a little before it reaches the Earth's surface. 
 
 In the former case, if a conjunction take place when the center of the Moon comes in a 
 direct line between the centers of the Sun and Earth, the dark shadow of the Moon will 
 fall centrally upon the Earth, and cover a circular area of 175 miles in diameter. To all 
 places lying within this dark spot, the Sun will be totally eclipsed, as illustrated by the 
 figure. 
 
 439. Eclipses of the Sun must always happen at New Moon, 
 and those of the Moon at Full Moon. The reason of this is, 
 that the Moon can never be between us and the Sun, to eclipse 
 him, except at the time of her change, or New Moon ; and she 
 can never get into the Earth's shadow, to be eclipsed herself, 
 except when she is in opposition to the Sun, and it is Full 
 Moon 
 
 440. If the Moon's orbit lay exactly in the plane of the eclip- 
 tic, she would eclipse the Sun at every change, and be eclipsed 
 herself at every full ; but as her orbit departs from the ecliptic 
 over 5 (422), she may pass either above or below the Sun at 
 
 438. What is the length of the Moon's shadow when she is nearest the Earth and 
 farthest from the Sun? What when nearest the Sun and farthest from the Earth? 
 What when the Sun and Moon are at their mean distances? 439. At wha' time of the 
 Moou oo bolar eclipses always occur? Lunar? Why? 440. Why not two solar an<l 
 
SJJ8 
 
 ASTRONOMY 
 
 the time of her change, or above or below the Earth's shadow 
 at the time of her full. 
 
 NEW AND FULL MOONS WITHOUT ECLIPSES. 
 
 ow above tile Earth. Above the Earth's shadow. 
 
 Shadow below the Earth. 
 
 Below the Earth's shadow. 
 
 Let the line joining the Earth and the Sun represent the plane of the ecliptic. Now as 
 tae orbit of the Moon departs from this plane about 5 9', she may appear either above 
 or below the Sun at New Moon, as represented in the figure, and her shadow may fall 
 above the north pole or below the south. At such times, then, there can be no solar 
 eclipse. 
 
 On the right, the Moon is shown at her full, both above and below the Earth's shadow, 
 in which case there can be no lunar eclipse. 
 
 441. As the Moon passes from one of her nodes to the other 
 in 173 days, there is just this period between two successive 
 eclipses of the Sun, or of the Moon. In whatever time of the 
 year, then, we have eclipses at either node, we may be sure that 
 in 173 days % after wards, we shall have eclipses at the other node. 
 
 As the Moon's nodes fall back, or retrograde in the ecliptic, at the rate of 19J6 every 
 year, they will complete a backward revolution entirely around the ecliptic to the same 
 point again, in 18 years, 225 days ; in which time there would always be a regular period 
 of eclipses, if any complete number of lunations were finished without a remainder. But 
 this never happens ; for if both the Sun and Moon should start from a line of conjunction 
 with either of the nodes in any point of the ecliptic, the Sun would perform IS annual 
 revolutions and 222 of another, while the Moon would perform 230 lunations, and 85 of 
 another, before the node would come around to the same point of the ecliptic again ; so 
 that the Sun would then be 138* from the node, and the Moon 85 from the Sun. 
 
 But after 228 lunations, or 18 years, 11 days, 7 hours, 42 minutes, and 81 seconds, the 
 Bun, Moon, and Earth, will return so nearly in the same position with respect to each 
 other, that there will be a regular return of the same eclipses for many ages. This 
 grand period was discovered by the Chaldeans, and by them called Saros. If, therefore, 
 to the mean time of any eclipse, either of the Sun or Moon, we add the Chaldean period 
 of JS years and 11 days, we shall have the return of the same eclipse. This mode of pre- 
 dicting eclipses will hold good for a thousand years. In this period there are usually 70 
 eclipses ; 41 of the Sun and 29 of the Moon 
 
 442. The diameter of the Earth's shadow, at the distance of 
 the Moon, is nearly three times as large as the diameter of the 
 Moon ; and the length of the Earth's shadow is nearly four times 
 as great as the distance of the Moon ; exceeding it in the same 
 ratio that the diameter of the Earth does the diameter of the 
 Moon ; which is as 3.663 to 1. 
 
 443. The number of eclipses in any one year, cannot be less 
 than two, nor more than seven. In the former case, they will 
 
 two lunar eclipses every lunar month? 441. How often may eclipses occur at oppo- 
 site nodes? What cycle of eclipses described? Number of eclipses in this cycle? 
 442. What is the diameter of the Earth's shadow at the distance of the Moon? 443. 
 What nuuiber of eclipses may occur in any one year? If but two, what will they be? 
 
SOLAR AND LUNAR ECLIPSES. 
 
 19 
 
 both be of the Sun ; and in the latter, there will be five of the 
 Sun, and two of the Moon those of the Moon will be total. 
 There are sometimes six ; but the usual number is four : two of 
 the Sun, and two of the Moon. 
 
 The cause of this variety is thus accounted for. Although the Sun usually passes 
 by both nodes only ouce ia a year, he may pass the same node again a little beforo 
 the end of the year. In consequence of the retrograde motion of the Moon's nodes, 
 he will come to either of them 173 days after passing the other. He may, there 
 fore, return to the same node in about 846 days, having thus passed one node twice, and 
 the other once, making each time, at each, an eclipse of both the Sun and the Moon, or 
 kijs h. all. And since 12 lunations, or 354 days from the first eclipse, in the beginning of 
 Hie yt.ar, leave room for another New Moon before the close of the year, and since this 
 New Moon may fall within the ecliptic limit, it is possible for the Sun to be eclipsed again. 
 Tims there may be seven eclipses in the same year. 
 
 444. Eclipses of the Sun always come on from the west, and 
 pass over eastward ; while eclipses of the Moon come on from 
 
 LUNA, KCUPSB. * c . east > arld V* over westward. SOLAR ECL[PSE 
 This is a necessary result of the 
 eastward motion of the Moon in 
 her orbit. 
 
 In the right hand cut, the Moon is seen 
 revolving eastward, throwing her shadow upon 
 the Earth, and hiding the western limb of the 
 Sun. In some instances, however, when the 
 eclipse is very slight, it may first appear on the 
 northern or southern limb of the Sun that is, 
 the upper or lower side; but even then its 
 direction must be from west to east. It will 
 also be obvious from this figure, that the sha- 
 dow of the Moon upon the Earth must also tra- 
 verse her surface from west to east ; conse- 
 quently the eclipse will be visible earlier in the 
 west than in the east. 
 
 On the left, the Moon is seen striking into 
 the Earth's shadow from the west, and having 
 her eastern limb first obscured. By holding the 
 book up south of him, the student will see at 
 once why the revolution of the Moon eastward 
 must cause a solar eclipse to proceed from west 
 to east, and a lunar eclipse from east to west. 
 To locate objects and motions correctly, the 
 student should generally imagine himself look- 
 ing to the south, as we are situated north of the 
 equinoctial. The student should bear in mind 
 that nearly all the cuts in the boik are drawn 
 to represent a view from northern latitude 
 upon the Earth. Hence, by holding the book 
 up south of him, the cuts will generally afford 
 an accurate illustration both of the positions 
 and motions of the bodies represented. 
 
 445. The time which elapses between two successive changes 
 of the Moon is called a Lunation, which, at a mean rate, is about 
 
 If seven? What is the usual number? Can you explain the cause of this variety P 
 444. What is the direction of a solar eclipse? A lunar? Why this difference? 445. 
 Whtit is a Itmalionf What would be the effect if the solar and lunar months w<.ro 
 What result from the existing inequality? 
 
 B.G. 
 
 10 
 
ASTRONOMY. 
 
 29^ days. If 12 lunar months were exactly equal to the 12 solar 
 months, the Moon's nodes would always occupy the same pointy 
 in the ecliptic, and all eclipses would happen in the same months 
 of the year, as is the case with the transits of Mercury and 
 Yenus : but, in 12 lunations, or lunar months, there are only 
 354 days ; and in this time the Moon has passed through both 
 her nodes, but has not quite accomplished her revolution around 
 the Sun ; the consequence is, that the Moon's nodes fall back iu 
 the ecliptic at the rate of about 19^ annually ; so that the 
 eclipses happen sooner every year by about 19 days. 
 
 446. Eclipses can never take place, except when the Moon 
 is near the ecliptic ; or, in other words, at or near one of her 
 nodes. At all other times, she passes above or below the Sun, 
 and also above or below the Earth's shadow. It is not neces- 
 sary that she should be exactly at her node, in order that an 
 eclipse occur. If she is within 17 of her node, at the time of 
 her change, she will eclipse the Sun ; and if within 12 of her 
 node at her full, she will strike into the Eariii's shadow, and be 
 more or less eclipsed. These distances are called, respectively, 
 the solar and lunar ecliptic limits. 
 
 This subject may be understood by consulting the following figure . 
 
 THE MOON CHANGING AT DIFFERENT DISTANCES FROM HER NODES. 
 
 Let the line E E represent the ecliptic, and the line the plane of the Moon's 
 .orbit. The light globes are the Sun, and the dark ones the Moon, which may be imagined 
 as much nearer the student ; hence their apparent diameter is the same. 
 
 Let the point A, represent the node of the Moon's orbit. Now if the change occur 
 when the Moon is at B, she will pass bflcnc the Sun. If when at C, she will just touch hia 
 lower limb. At C, she will eclipse him a little, and so on to A; at which point, if the 
 change occurs, the eclipse would be central, and probably total. 
 
 If the Moon was at Gr, H, I, or J, in her orbit, when the change occurred, she would 
 eclipse the upper or northern limb of the Sun, according to her distance from her node 
 at the time ; but if she was at K, she would pass above the Sun, and would not eclipse 
 him at all. The points C and J will represent the Solar Ecliptic Limits. 
 
 The mean ecliptic limit for the Sun is 16}^ on each side of the node ; the mean eclip- 
 tic limit for the Moon is 10,^ on each side of the node. In the former case, then, there 
 are 33 degrees about each node, making, in all, 66 out of 860, in which eclipses of the 
 Sun may happen ; in the latter case there are 21 about each node, making, in all, 42* 
 out of 360 in which eclipses of the Moon usually occur. The proportion of the solar to 
 the lunar eclipses, therefore, is as 66 to 42, or as 11 to 7. Yet, there are more visible 
 *=ulipses of the Moon, at any given place, than of the Sun ; because a lunar eclipse id 
 visible to a whole hemisphere, a solar eclipse only to a small portion of it. 
 
 447. All parts of a planet's shadow are not alike dense. The 
 
 4-1(5. Where must the Moon be, with respect to the ecliptic and her nodes, in order to 
 an eclipse? What meant by ecliptic Urn UK ? Name the distance of each, respectively, 
 from the node. Illustrate. 447. What is the umbra of the Earth or Moon? The 
 
SOLAR AND LUNAR ECLIPSES. 221 
 
 darkest portion is called the umbra, and the partial shadow the 
 penumbra. 
 
 UMBRA AND PC1TTTHBRA CF THE EARTH AND MOOS. 
 
 Penumbra is from the Latin pene, almost, and ivrribra, a shadow. In this cut, the 
 Earth's umbra and penumbra will be readily found by the lettering ; while A is the umbra, 
 and B B the penumbra, of the Moon. The latter is more broad than it should be, owing 
 to the nearness of the Sun in the cut, as it never extends to much over half the Earth's 
 diameter. The student will see at once that solar eclipses can be total only to persons 
 Tithin the umbra ; while to all on which the penumbra falls, a portion of the Sun's disc 
 will be obscured. 
 
 448. The average length of the Earth's umbra is about 
 860,000 miles ; and its breadth, at the distance of the Moon, is 
 about 6500 miles, or three times the Moon's diameter. 
 
 As both the Earth and Moon revolve in elliptical orbits, both the above estimates are 
 subject to variations. The length of the Earth's umbra varies from 842,217 to 871,262 
 miles ; and its diameter, where the moon passes it, varies from 5235 to 6365 miles. 
 
 449. The average length of the Moon's umbra is about 
 239,000 miles. It varies from 221,148 to 252,638 miles, 
 according to the Moon's distance from the Sun. Its greatest 
 diameter, at the distance of the Earth, is ItO miles ; but the 
 yenumbra may cover a space on the Earth's surface 4393 miles 
 in diameter. 
 
 When the Moon but just touches the^imb of the Sun, or the 
 umbra of the Earth, it is called an appulse (see C and J in the 
 cut on the opposite page). 
 
 450. A partial eclipse is one in which only part of the Sun or 
 Moon is obscured. A solar eclipse is partial to all places 
 outside the umbra ; but within the umbra, where the whole 
 disc is obscured, the eclipse is said to be total. A central eclipse 
 is one taking place when the Moon is exactly at one of her nodes. 
 If lunar, it is total, as the Earth's umbra is always broad enough, 
 at the Moon's distance, if centrally passed, to obscure her whole 
 disc. But a solar eclipse may be central and not total, as the 
 Moon is not always of sufficient apparent diameter to cover the 
 
 Henumbraf Derivation? Within which are solar eclipses total? 448. The average 
 length of the Earth's shadow? Breadth at the Moon's distance? Do they vary? Why? 
 i49. Average length of the Moon's umbra? Does it vary ? Why? Greatest diameter 
 at the Earth's surface? Of penumbra? What is an appulse f 450. A par-tint 
 eclipse? Atotalf ^.central? Are all centra) 'tclinses total? Why not? What calh-d 
 then? Why? 
 
222 
 
 ASTRONOMY. 
 
 whole disc of the Sun. In that case, the eclipse would be 
 annular (from annulus, a ring), because the Moon only hides the 
 center of the Sun, and leaves a bright ring unobscured. 
 
 Going o3. 
 
 PROGRESS OF A CENTRAL ECLIPSE. 
 
 Annular. 
 
 Coming ou. 
 
 451. It has already been shown that the apparent magni- 
 tudes of bodies vary as their distances vary ; and as both the 
 Earth and Moon revolve in elliptical orbits, it follows that the 
 Moon and Sun must both vary in their respective apparent mag- 
 nitudes. Hence some central eclipses of the Sun are total, 
 while others are partial and annular. 
 
 TOTAL AND ANNULAR ECLIPSES OF THE SUN 
 
 At A, the Earth is at her aphelion, and the Sun being at his most distant point, will 
 fiave his least apparent magnitude. At the same time, the Moon is in perigee, and 
 appears larger than usual. If, therefore, she pass centrally over the Sun's disc, tho 
 eclipse will be total. 
 
 At B, this "order is reversed. The Earth is at her perihelion, and the Moon in apogee; 
 so that the Sun appears larger, and the Moon smaller than usual. If, then, a central 
 eclipse occur under these circumstances, the Moon will not be large enough to eclipse the 
 whole of the Sun, but will leave a ring, apparently around herself, unobscured. Such 
 eclipse will be annular. 
 
 452. The greatest possible duration of the annular appearance 
 of a solar eclipse, is 12 minutes and 24 seconds; and the greatest 
 possible time during which the Sun can be totally eclipsed, to 
 any part of the world, is 7 minutes and 58 seconds. The Moon 
 may continue totally eclipsed for one hour and three quarters. 
 
 553. As the solar ecliptic's limits are further from the Moon's 
 nodes than the lunar, it results that we have more eclipses of 
 the Sun than of the Moon. There may be seven in all in one 
 
 451. Why are buu.3 central eclipses total, and others partial and annular? 452. 
 How long may an annului eclipse continue ? A total eclipse of the Sun ? Of the Moon? 
 453. Which kind of eclipses is most frequent? Why? The greatest number in a year f 
 
SOLAR AND LUNAR ECLIPSES. 223 
 
 year, viz., five solar and two lunar ; but the most asual number 
 is four. There can never be less than two in a year ; in which 
 case, both must be of the Sun. Eclipses both of the Sun and 
 Moon recur in nearly the same order, and at the same intervals, 
 at the expiration of a cycle of 223 lunations, or 18 years of 365 
 days and 15 hours. This cycle is called the Period of the 
 Eclipses. At the expiration of this time, the Sun and the 
 Moon's nodes will sustain the same relation to each other as at 
 the beginning, and a new cycle of eclipses begins. 
 
 454. In a total eclipse of the Sun, the heavens are shrouded 
 in darkness, the planets and stars become visible, the tempera- 
 ture declines, the animal tribes become agitated, and a general 
 gloom overspreads the landscape. Such were the effects of the 
 great eclipse of 1806. In a lunar eclipse, the Moon begins to 
 lose a portion of her light and grows dim, as she enters the 
 Earth's penumbra, till at length she comes in contact with the 
 umbra, and the real eclipse begins. 
 
 455. In order to measure and record the extent of eclipses, 
 the apparent diameters of the Sun and Moon are divided into 
 twelve equal parts, called digits; and in predicting eclipses, 
 astronomers usually state which "limb" of the body is to be 
 eclipsed the southern or northern the time of thd first con- 
 tact, of the nearest approach of centers, direction, And number 
 of digits eclipsed. 
 
 FIVE DIGITS ECLIPSED. TWELVE DIGITS. , 
 
 456. The last annular eclipse visible in the United States, 
 occurred May 26, 1854. The next total eclipse of the Sun will 
 be August 7, 1869. 
 
 Some of the ancients, and all barbarous nations, formerly 
 regarded eclipses with amazement and fear, as uupernaturul 
 events, indicating the displeasure of the gods. Cc ambus is said 
 
 How many of each? Least number, and which? Usual number? What said of the 
 order of eclipses? Time of cycle? 454. Describe the effects of t total eclipse of the 
 Sun. The process of a lunar eclipse? 455. How are eclipses measured and recorded? 
 456. When the next annular eclipse visible in this country ? The neat total? How huvc 
 
224 
 
 ASTRONOMY. 
 
 to have made a very happy use of this superstition, as already 
 stated on a previous page. (Art. 433.) 
 
 457. Eclipses can be calculated with the greatest precision, 
 not only for a few years to come, but for centuries and ages 
 either past or to come. This fact demonstrates the truth of the 
 Copernican theory, and illustrates the order and stability that 
 everywhere reign throughout the planetary regions. 
 
 The following is a list of all the solar eclipses visible in Europe and America from 
 1858 to the close of the present century. To those visible in New England, the number 
 of digits is annexed. 
 
 Year. 
 
 Month. 
 
 Day and hour. 
 
 Digits. 
 
 Year. 
 
 Month. 
 
 Day and hour. 
 
 Digits. 
 
 1868, 
 1669, 
 
 Mar. 
 July 
 
 15 6 14 A. M. 
 29 5 32 P. M. 
 
 1% 
 2>$ 
 
 1878, 
 1879, 
 
 July 
 July 
 
 29 4 56 P. M. 
 19 2 A. M. 
 
 IK 
 
 1860, 
 
 July 
 
 18 7 23 A. M. 
 
 6H 
 
 1830, 
 
 Dec. 
 
 31 7 30 A. M. 
 
 5H 
 
 1S61, 
 
 Dec. 
 
 31 7 30 A. M. 
 
 4^ 
 
 1882, 
 
 May 
 
 17 1 A. M. 
 
 
 1S63, 
 
 May 
 
 17 1 P. M. 
 
 
 1885, 
 
 Mar. 
 
 16 35 A. M. 
 
 6* 
 
 1865, 
 
 Oct. 
 
 19 9 10 A. M. 
 
 3% 
 
 1886, 
 
 Aug. 
 
 29 6 30 A. M. 
 
 0* 
 
 1866, 
 
 Oct. 
 
 8 11 12 A. M. 
 
 
 
 1887, 
 
 Aug. 
 
 18 10 P. M. 
 
 
 186T, 
 
 Mar. 
 
 6 8 A. M. 
 
 
 1890, 
 
 June 
 
 17 8 A. M. 
 
 
 1868, 
 
 Feb. 
 
 23 10 A. M. 
 
 
 1891, 
 
 June 
 
 600 Mer. 
 
 
 1869, 
 
 Aug. 
 
 7 5 21 A. M. 
 
 lOli 
 
 1892, 
 
 Oct. 
 
 20 19 P. M. 
 
 854 
 
 1870, 
 
 Dec. 
 
 22 6 A. M. 
 
 1 
 
 1895, 
 
 Mar. 
 
 26 4 A. M. 
 
 
 1873, 
 
 May 
 
 26 3 A. M. 
 
 
 1896, 
 
 Aug. 
 
 900 Mer. 
 
 1874, 
 
 Oct. 
 
 10 4 A. M. 
 
 
 1897, 
 
 July 
 
 29 9 8 A. M. 1 4% 
 
 1875, 
 
 Sept. 
 
 29 5 56 A. M. 
 
 n% ; 
 
 1899, 
 
 June 
 
 800 Mer. 
 
 1876, 
 
 Mar. 
 
 25 4 11 P. M. 
 
 3% ! 
 
 1900, 
 
 May 
 
 28 8 9 A. M. 1 11 
 
 The eclipses of 1869, 1875, and 1900 will be yery large. In those of 1873, 1875, and 
 18SO, the Sun wili. rise eclipsed. 
 
 That of 1875 will be annular. The scholar can continue thii table, or extend it *vjck- 
 war<'<?,-by adding or substracting the Chaldean period of 18 years, 11 days, 1 hours, 5-i 
 minutes, and 31 seconds. 
 
 CHAPTER YI. 
 
 PRIMARY PLANETS CONTINUED-MARS AND THE 
 ASTEROIDS. 
 
 458. MARS is the first of the exterior planets, its orbit lying 
 jmmediately without, or beyond, that of the Earth, while those 
 of Mercury and Venus are within. He appears, to the naked 
 eye, of a fine ruddy complexion ; resembling, in color, and appa- 
 
 the ignorant and superstitious regarded eclipses ? 457. What said of the calculation of 
 eclipses? What does this demonstrate and illustrate? 458. Position of Mars' orbit? 
 Row doeu he appoar to the naked eye? When most brilliant? When least? 
 
THE PRIMARY PLANETS MARS AND THE ASTEROIDS. 225 
 
 rent magnitude, the star Antares, or Aldebaran, near which it 
 frequently passes. It exhibits its greatest brilliancy about the 
 time that it rises when the Sun sets, and sets when the Sun 
 rises ; because it is then nearest the Earth. It is least brilliant 
 when it rises and sets with the Sun ; for then it is five times farther 
 removed from us than in the former case. 
 
 459. Its distance from the Earth at its nearest approach is 
 about 50,000,000 of miles. Its greatest distance from us is 
 about 240,000,000 of miles. In the former case, it appears 
 nearly 25 times larger than in the latter. When it rises before 
 the Sun, it is our morning star ; when it sets after the Sun, it ia 
 our evening star. 
 
 The distance of the interior planets from the earth, varies within the limits of the 
 di.-imeters of their respective orbits ; for when a planet is in that part of its orbit which 
 is nearest the Earth, it is evidently nearer by the whole diameter of its orbit, than it is 
 when at a point opposite, on the other side of its orbit. The exterior planets vary in 
 distance within the limits of the diameter of the Earth's orbit. 
 
 460. Mars is sometimes seen in opposition to the Sun, and 
 sometimes in superior conjunction with him ; sometimes gibbous, 
 but never horned. In conjunction, it is never seen to pass over 
 the Sun's disc, like Mercury and Venus. These prove not only 
 that its orbit is exterior to the Earth's orbit, but that iHs an 
 opaque body, shining only by the reflection of the Sun. 
 
 461. The motion of Mars through the constellations of the 
 zodiac is but little more than half as great as that of the Earth; 
 it being generally about 57 days in passing over one sign, which 
 is at the rate of a little more than half a degree each day. Thus, 
 if we know what constellation Mars enters to-day, we may con- 
 clude that two months hence it will be in the next constellation ; 
 four months hence, in the next ; six months, in the next, and 
 so on. 
 
 Its mean sidereal revolution is performed in 686.9796458 solar days ; or in 686 days, 23 
 hours, 30 minutes, 41.4 seconds. Its synodical revolution is performed in 779.936 solar 
 days ; or in 779 days, 22 hours, 27 minutes, and 50 seconds. 
 
 462. Mars performs his revolution around the Sun in one 
 year and 10^ months, at the distance of 145,000,000 of miles ; 
 moving in its orbit at the mean rate of 55,000 miles an hour. 
 Its diurnal rotation on its axis is performed in 24 hours, 39 
 
 459. Its distance from the Earth? What effect upon its apparent magnitude ? When 
 morning and evening star ? How do the distances of the planets from the Earth vary \ 
 Their apparent diameters ? 460. Is Mars ever in opposition to the Sun? In conjunc- 
 tion? Its phases? Does it ever transit the Sun? What do these facts prove ? 461. 
 What is his rate of motion through the constellations ? What calculation based upon it '/ 
 462. His periodic time ? Distance from the Sun ? Mean rate of motion per hour? Time 
 o:' rotation on his axis? How does his day compare with ours ? 
 
226 ASTRONOMY. 
 
 minutes, and 21 seconds ; which makes its day about 44 min- 
 utes longer than ours. 
 
 463. Its form is that of an oblate spheroid, whose polar 
 diameter is to its equatorial, as 15 is to 16, nearly. Its diameter 
 is 4,500 miles. Its bulk, therefore, is 7 times less than that of 
 the Earth ; and being 50,000,000 of miles farther from the Sun, 
 it receives from him only half as much light and heat. 
 
 464. The inclination of its axis to the plane of its orbit, is 
 about 28f. Consequently, its seasons must be very similar to 
 those of the Earth. Indeed, the analogy between Mars and the 
 Earth is greater than the analogy between the Earth and any 
 other planet of the solar system. Their diurnal motion, and of 
 course the length of their days and nights, are nearly the same ; 
 the obliquity of their ecliptics, on which the seasons depend, are 
 not very different ; and, of all the superior planets, the distance 
 of Mars from the Sun is by far the nearest to that of the Earth ; 
 nor is the length of its year greatly different from ours, when' 
 compared with the years of Jupiter, Saturn and Uranus. 
 
 465. To a spectator on this planet, the Earth will appear 
 alternately, as a morning and evening star ; and will exhibit all 
 the phases of the Moon, just as Mercury and Yenus do to us ; 
 and sometimes like them, will appear to pass over the Sun's disc 
 like a dark round spot. Our Moon will never appear more than 
 a quarter of a degree from the Earth, although her distance from 
 it is 239,000 miles. If Mars be attended by a satellite, it is too 
 small to be seen by the most powerful telescopes. 
 
 When it is considered that Vesta, the smallest, of the asteroids, which is once and .* 
 half times the distance of Mars from us, and only 269 miles in diameter, is perceivable 
 in the cpen space, and that without the presence of a more conspicuous body to point it 
 out, we may reasonably conclude that Mars is without a Moon. 
 
 466. The progress of Mars in the heavens, and indeed of all 
 the superior planets, will, like Mercury and Yenus, sometimes 
 appear direct, sometimes retrograde, and sometimes he will seem 
 stationary. The portion of the ecliptic through which a planer 
 seems to retrograde is called the Arc of Retrogradation. Thb 
 more remote the planet the less the arc, and the longer the time 
 of its retrogression. These retrograde movements and stations, 
 as they appear to a spectator from the Earth, are common to 
 all the planets, and demonstrate the truth of 'the. Copernican 
 system. 
 
 463. Form of Mars ? Diameter? Bulk? Light and heat? 464. Inclination of his 
 axis to the plane of his orbit? His seasons? Resemblance to our globe? 465. How 
 would the Earth appear to a spectator upon Mars ? Our Moon ? Has Mars a satellite ? 
 466. What said of the motions of Mars and the other planets? What constitutes *h-_ 
 
THE PRIMARY PLANETS MARS AND THE ASTEROIDS. 227 
 
 RETROGRADE MOTION OF THE EXTERIOR PLANETS. 
 
 Suppose the Earth at A, and the planet Neptune at B, he would then appear to be at C, 
 among the stars ; but as Neptune moves but a little from B toward F, while the Earth h> 
 passing from A to D, Neptune will appear to retrograde from C to E. Whatever Neptune 
 may have moved, however, from B toward F, will go to reduce the amount of apparent 
 retrogression. 
 
 It is obvious from this figure-, that the more distant an exterior planet is, and the slower 
 it moves, the less will be its arc of retrogradation, and the longer will it be retrograding. 
 Neptune appears to retrograde 180 days, or nearly half the year. 
 
 The following table exhibits the amownt of arc and the Ume of the retrogradation of 
 the principal planets : 
 
 Arc. Days. 
 
 Mercury 13% 23 
 
 Venus 16 42 
 
 Mars 16 73 
 
 Jupiter 10 121 
 
 Saturn 6 139 
 
 Uranus 4 151 
 
 Neptune.. 1 180 
 
 TELESCOPIC APPEARANCES OF MARS. 
 
 The right-hand figure represents Mars as seen at the Cincinnati Observatory, August 5, 
 1845. On the 30th of the same month he appeared as represented on the left. lu 
 middle view is from a d-awing by Dr. Dick. 
 
 467. The telescopic phenomena of Mars afford peculiar interest 
 to astronomers. They behold its disc diversified with numerous 
 irregular and variable spots, and ornamented with zones and 
 belts of varying brilliancy, that form, and disappear, by turns. 
 Zones of intense brightness are to be seen in its polar regions, 
 subject, however, to gradual changes. That of the southern 
 pole is much the most brilliant. I)r. Herschel supposes that 
 they are produced by the reflection of the Sun's light from tho 
 frozen regions, and that the melting of these masses of polar ice 
 is the cause of the variation in their magnitude and appearance. 
 
 Arc of Eftrogradation f What do these motion? prove? 4G7. How does Mars appear 
 through a telescope? Dr. Herschei'a opinion of its polar regions? H^w conl-rmeU iu 
 
 10* 
 
228 ASTRONOMY. 
 
 He was the more confirmed in these opinions by observing that after the exposure of 
 the luminous zone about the north pole to a summer of eight months, it was considerably 
 decreased, while that on the south pole, which had been in total darkness during sight 
 mouths, had considerably increased. He observed, farther, that when this spot wae 
 most luminous, the disc of Mars did not appear exactly round, and that the bright part 
 of its southern limb seemed to be swollen or arched out beyond the proper curve. 
 
 468. The extraordinary height and density of the atmosphere 
 of Mars, are supposed to be the cause of the remarkable redness 
 of its light. It has been found, by experiment, that when a 
 beam of white light passes through any colorless transparent 
 medium, its color inclines to red, in proportion to the density of 
 die medium, and the space through which it has traveled. Thus 
 the Sun, Moon, and stars, appear of a reddish color when near 
 'the horizon ; and every luminous object, seen through a mist, is 
 of a ruddy hue. 
 
 This phenomena may be thus explained : The momentum of the red, or least refrangi- 
 ble rays, being greater than that of the violet, or most refrangible rays, the former will 
 make their way through the resisting medium, while the latter are either reflected or 
 absorbed. The color of the beam, therefore, when it reaches the eye, must partake of 
 the color of the least refrangible rays, and this color must increase with the distance. 
 The dim light, therefore, by which Mars is illuminated, having to pass twice through its 
 atmosphere before it reaches the Earth, must be deprived of a great proportion of its 
 violet rays, and consequently then be red. Dr. Bru water supposes that the difference of 
 color among the other planets, and even the fixed stars, is owing to the different heighta 
 and densities of their atmospheres. 
 
 THE ASTEROIDS, OK TELESCOPIC PLANETS. 
 
 469. Ascending higher in the solar system, we find, between 
 the orbits of Mars and Jupiter, a cluster of eighty-five small 
 planets, which present a variety of anomalies that distinguish 
 them from all the older planets of the system. The first of 
 these, namely, Ceres, was discovered by Piazzi, at Palermo, 
 January 1, 1801; and three others, namely, Pallas, Juno, and 
 Vesta, have been known since 1807. The remaining eighty-one 
 
 have all been discovered since that time, and most of them since 
 1853. 
 
 470. The scientific Bode entertained the opinion, that the 
 planetary distances, above Mercury, formed a geometrical series, 
 3ach exterior orbit being double the distance of its next interior 
 one, from the Sun ; a fact which obtains with remarkable exact- 
 ness between Jupiter, Saturn, and Uranus. But this law seemed 
 to be interrupted between Mars and Jupiter. Hence he inferred, 
 that there was a planet wanting in that interval ; which is now 
 
 this opi ion? 468. Supposed cause of the ruddy color of Mars? Philosophical expla- 
 nation * Dr. firewater's opinion ? 469. Position and numi ^r of the asteroid* ? When 
 discover d? 470. Bode's theory? What seeming interruption? What conclusioi ? 
 
THE PRIMARY PLANETS MARS AND THE ASTEROIDS. 2"*J 
 
 happily supplied by the discovery of the numerous star-form 
 planets, occupying the very space where the unexplained vacancy 
 presented a strong objection to his theory. 
 
 According to Bode, the distances of the planets may be expressed nearly as follows : the 
 Earth's distance from the Sun being 10. 
 Mercury 4 
 
 Venus 4+3x1 = 7 
 
 The Earth 4 + 3x2 = 10 
 
 Mara 4+3x22 - 16 
 
 Asteroids 4+3x23 = 23 
 
 Jupiter 4+3 x2 4 = 52 
 
 Saturn 4+3x2 = 100 
 
 Herschel 4+3x23 = 196 
 
 Comparing these values with the actual mean distances of the planets from the Sun, 
 Tit, cannot but remark the near agreement, and can scarcely hesitate to pronounce that 
 the respective distances of the planets from the Sun, were assigned according to a lav, 
 although we are entirely ignorant of the exact law, and of the reason for that law. 
 Brinkley's Elements, p. 89. 
 
 411. The Asteroids are much smaller in size than the older 
 planets they all revolve at nearly the same distances from the 
 Sun, and perform their revolutions in nearly tfie same periods 
 their orbits are much more eccentric, and have a much greater incli- 
 nation to the ecliptic and what is altogether singular, except in 
 the case of comets some of their orbits cross each other ; so that 
 there is even a possibility that two of these bodies may, some 
 time, in the course of their revolutions, come into collision. 
 
 The orbit of Vesta is so eccentric, that she is sometimes 
 farther from the Sun than either Ceres, Pallas, or Juno, although 
 her mean distance is many millions of miles less than theirs. The 
 orbit of Vesta crosses the orbits of several other asteroids, in 
 two opposite points. 
 
 The student should here refer to the Figures, Map I. of the Atlas, and verify such of 
 those particulars as are there represented. It would be well for the teacher to require 
 him to observe particularly the positions of their orbits, and to state their different 
 degrees of inclination to the plane of the ecliptic. 
 
 472. From these and other circumstances, many eminent 
 astronomers are of opinion, that these eighty-five planets arc 
 the fragments of a large celestial body which once revolved 
 between Mars and Jupiter, and which burst asunder by some 
 tremendous convulsion, or some external violence. The dis- 
 covery of Ceres, -by Piazzi, on the first day of the present cen- 
 tury, drew the attention of all the astronomers of the age to 
 that region of the sky, and every inch of it was minutely explor- 
 ed. The consequence was, that in the year following, Dr. Olbers, 
 of Bremen, announced to the world the discovery of Pallas, 
 situated not many degrees fro;> Ceres, and very much resembling 
 it in size. 
 
 How substantially ju^.fied? 471. Size of the asteroids? Distance from the Sun? 
 Periodic time? Forms of their orbits? Position with respect to the ecliptic ' Wha', 
 other singularity in their orbits ? What remarkable facts respecting the orbit 01 Vesta ? 
 413. Whal conclusion has been drawn froir these facts? Progress of discovery? 
 
ASTRONOMY. 
 
 473. From this discovery, Dr. Olbers first conceived the idea 
 that these bodies might be the fragments of a former world ; and 
 if so, that other portions of it might be found either in the same 
 neighborhood, or else, having diverged from the same point, 
 " they ought to have two common points of reunion, or two 
 nodes in opposite regions of the heavens through which all the 
 planetary fragments must sooner or later pass," 
 
 474. One of these nodes he found to be in the constellation 
 Virgo, and the opposite one in the Whale ; and it is a remark- 
 able coincidence that it was in the neighborhood of the latter 
 constellation that Mr. Harding discovered the planet Juno. In 
 order, therefore, to detect the remaining fragments, if any 
 existed, Dr. Olbers examined, three times every year, all the 
 small stars in Virgo and the Whale ; and it was actually in the 
 constellation Virgo, that he discovered the planet Vesta. Since 
 that time, eighty-one additional asteroids have been discovered, 
 and it is not unlikely that still additional fragments of a similar 
 description will hereafter be discovered. 
 
 Dr. Brewster attributes the fall of meteoric stones to the 
 smaller fragments of these bodies happening to come within the 
 sphere of the Earth's attraction. 
 
 Meteoric stones, or what are generally termed aerolites, are stones which sometimes 
 fall from the upper regions of the atmosphere upon the Earth. The substance of which 
 they are composed, is, for the most part, metallic,; but the ore of which it consists is not 
 to be found in the same constituent proportions in any known substance upon the Earth. 
 Their fall is generally preceded by a luminous appearance, a hissing noise, and a loud 
 explosion ; and when found immediately after their descent, they are always hot, and 
 usually covered with a black crust, indicating a state of exterior fusion. 
 
 Their size varies from that of small fragments of inconsiderable weight to that of the 
 most ponderous masses. They have been found to weigh from 300 pounds to several tons ; 
 and they have descended to the earth with a force sufficient to bury them many feet 
 under the surface. 
 
 Some have supposed that they are projected from volcanoes in the Moon ; others that 
 they proceed from volcanoes on the Earth ; while others imagine that they are gene- 
 rated in the regions of the atmosphere ; but the truth probably is not yet. ascertained, li 
 some instances, these stones have penetrated through the roofs of houses, and proved 
 destructive to the inhabitants. 
 
 If we carefully compute the force of gravity in the Moon, we shall find that if a body 
 were projected from her surface with a momentum that would cause it to move at the rate 
 of 82uO feet in the first second of time, and in the direction of a line joining the centers 
 of the Earth and Moon, it would not fall again to the surface of the Moon ; but would 
 become a satellite to the Earth. Such an impulse might, indeed, cause it, even after 
 many revolutions, to fall to the earth. The fall, therefore, of these stones, from the air, 
 may be accounted for in this manner. 
 
 Mr. Harte calculates, that even a velocity of 6000 feet in a second, would be sufficient 
 to carry a body projected from the surface of the Moon beyond the power of her attrac- 
 tion. If so, a projectile force three times greater than that of a cannon, would carry a 
 a body from the Moon, beyond the point of equal attraction, and cause it to reach the 
 Earth. A force equal to this is often exerted by our volcanoes, and by subterranean 
 steam. Hence, there is no impossibility in the supposition of their coming from the Moon. 
 
 473. Theory of Dr. Olbers ? 474. Where did he find these nodes? What remarkable 
 coincidence? Dr. Olbers' efforts ? Discoveries since? Dr. Brewster's idea respecting 
 noteoric stones ? What are meteoric stones? Circumstances of their fall ? Sizis and 
 vciynt? Supposed origin ? Coul-i they have fallen fror the Moon? What computation:; f 
 
THE PRIMARY PLANETS TABLE OF THE ASTEHOIDS. 23* 
 
 475. Vesta appears like a star of the sixth magnitude, and io 
 the only asteroid that can be seen by the naked eye. 
 
 476. Juno revolves around the sun in 4 years 4^- months. 
 Her diameter is estimated at 1,393 miles. She is noted for the 
 great eccentricity of her orbit. Ceres' diameter is estimated at 
 1,585 miles, and Pallas' at 2,025. 
 
 TABLE OF THE ASTEROIDS. 
 
 477. The following table comprises the names, distances, 
 periods, etc., of the Asteroids, so far as known. They are 
 placed in the order of their discovery. 
 
 No. Names. 
 
 Distance from 
 the Sun in 
 Miles. 
 
 Periodic 
 time in 
 Days. 
 
 time of 
 discovery. 
 
 By whom 
 discovered; 
 
 Wh?re 
 discnve a 
 
 1. Ceres 
 2. Pallas 
 
 262,764,110 
 263,186,670 
 253.524,410 
 224,327,205 
 244.767,500 
 230,414,710 
 22<5, 683.965 
 209,131,670 
 226,644.350 
 299,190,435 
 232,995,860 
 221,617.045 
 244,684,375 
 245,989,960 
 251,197,100 
 277,661,440 
 235.002,450 
 218,125,700 
 231,929,960 
 228,891,670 
 231,365.945 
 237,080,005 
 249,738.280 
 299.244,965 
 228,100,700 
 252,327,505 
 222,993,975 
 263,641,815 
 242,712,270 
 224,598,905 
 299,835,010 
 245.958,705 
 272,372,125 
 255,388,690 
 
 1,680 
 1,684 
 1,592 
 1,325 
 1,511 
 1,380 
 1,346 
 1,193 
 1,346 
 2.041 
 1,403 
 1,301 
 1,510 
 1,522 
 1,570 
 1,825 
 1,421 
 1,271 
 1,393 
 1,366 
 1,388 
 1,440 
 1,557 
 2,042 
 1,859 
 1,581 
 1,314 
 1,689 
 1,492 
 1,328 
 2,048 
 1,522 
 1,773 
 1,610 
 
 Jan. 1. 1801 
 March 28, 1802 
 Sept. 1, 1804 
 March 29, 1807 
 Dec. 8, 1845 
 July 1, 1847 
 Aug. 13. 1847 
 Get 18, 1847 
 April 25,1848 
 April 12,1849 
 May 13, 1850 
 Sept 13,1850 
 Nov. 2, 1850 
 May 20, 1851 
 July 29, 1851 
 March 17, 1852 
 April 17,1852 
 June 24,1852 
 Aug. 22, 1852 
 Sept 19,1852 
 Nov. 15, 1852 
 Nov. 16, 1852 
 Dec. 15, 1852 
 April 5, 1853 
 April 6, 1853 
 May 5, 1853 
 Nov. 8. 1853 
 March 1, 1854 
 March 1, 1854 
 July 22, 1854 
 Sept. 1, 1854 
 Oct 26, 1854 
 Oct 28, 1854 
 April 15, 1855 
 
 Piazzi 
 Dr. Olbers 
 Harding.. 
 Dr. Olbers 
 Hencke.. 
 Hencke. 
 Hind.... 
 Hind. . . . 
 Graham . 
 De Gasparis 
 De Gasparis 
 Hind 
 De Gasparis 
 Hind 
 
 Palermo. 
 Bremen. 
 Lilienthal. 
 Bremen. 
 Drh'sden. 
 Driesden. 
 London. 
 London. 
 Markvee. 
 Naples. 
 Naples. 
 London. 
 Naples. 
 London. 
 Naples. 
 Naples. 
 Bilk. 
 London. 
 London. 
 Marseilles. 
 Paris. 
 London. 
 London. 
 Naples. 
 Marseilles 
 Bilk. 
 London. 
 Bilk. 
 London. 
 London. 
 Washington, D. CL 
 Paris. 
 Paris. 
 Paris. 
 
 8 Juno. . . . 
 
 4. Vesta 
 5. Astrsea. 
 6. Hebe 
 
 7 Iris. 
 
 8. Flora 
 9. Metis 
 10. Hyeeia 
 11. Parthenope . 
 12 Clio 
 
 13. Egeria 
 14. Irene 
 15. Ennomia . . . 
 16. Psyche 
 17. Thetis 
 18. Melpomena 
 19. Fortuna 
 20. Massilia .... 
 21. Lutetia 
 22. Calliope 
 23. Thalia 
 24. Themis 
 25. Phoctea 
 26. Proserpine.. 
 27. Euterpe 
 28. Bellona.... 
 29. Amphitrite . 
 80. Urania 
 81. Euphrosyne 
 82. Pomona 
 83. Polymnia... 
 84. Circe 
 
 De Gasparis 
 De Gasparis 
 Luther 
 Hind 
 Hind 
 Chacornac.. 
 Goldsmidt.. 
 Hind 
 Hind . 
 
 De Gasparis 
 Chacomac . . 
 Luther 
 Hind... 
 Luther 
 Marth 
 Hind 
 Ferguson .. 
 Goldsmidt 
 Chacornac. . 
 Chacornac.. 
 
 475. Appearance of Vesta. 476. Juno's period. Diameter. For ^hat noted ? Di 
 meter of Ceres. Of Pallas. 477. Numbei of asteroids now kno^vn a* per tabl 
 
232 ASTBOXOHY 
 
 TA3LE OF THE ASTEROIDS. Continued. 
 
 No. Names. 
 
 Distance from 
 the Sun in 
 Mil^B. 
 
 Periodic 
 time in 
 Days. 
 
 T'me of 
 discovery. 
 
 By whim 
 discovered. 
 
 Wh^re 
 discovert d. 
 
 86. Leucothea . . 
 86. Atalanta.... 
 87 Fides 
 
 288,216,755 
 261.126,975 
 255,981,165 
 260.270,075 
 263,091,765 
 215,379,060 
 228.032,015 
 231,219,455 
 209,364,610 
 230,886,670 
 260,568.660 
 241.296.960 
 273,641,325 
 295.150,275 
 293,180,925 
 251vS44,430 
 225,901,640 
 294,330,710 
 248,224,930 
 258,811,540 
 263,965,195 
 245,428,700 
 299,942.265 
 255,971,895 
 257.714,955 
 227,203,995 
 285.377,815 
 297.430,750 
 221654,200 
 254.437,170 
 325;996,965 
 252,117,278 
 229,421,200 
 258.652.510 
 290,924,010 
 253.662,065 
 208,788,740 
 261,841,470 
 254.435,102 
 244.645.135 
 261,121,806 
 302,955,000 
 253,521,413 
 262,418,500 
 232.294,000 
 215.390,742 
 263,981,794 
 257,814,930 
 232,297,428 
 225,900,271 
 252,117,294 
 
 1,880 
 1,665 
 1,568 
 1,656 
 1,683 
 1,247 
 1,358 
 1,887 
 1,195 
 1.384 
 L659 
 1,479 
 1.786 
 2,000 
 1.980 
 1,577 
 1.839 
 1,992 
 1,543 
 1,642 
 1,692 
 1,517 
 2,049 
 1,615 
 1,632 
 1,351 
 1,902 
 2,024 
 1,355 
 1,601 
 2,322 
 1,579 
 1,371 
 1,641 
 1,957 
 1,594 
 1,148 
 1,671 
 1,589 
 1,509 
 1,570 
 2,080 
 1,597 
 1,677 
 1,397 
 1,271 
 1,693 
 1.659 
 1.382 
 1,824 
 1,572 
 
 April 19,1855 
 Oct. 5, 1855 
 Oct. 5, 1855 
 Jan. 12, 1856 
 Feb. 8, 1856 
 March 81, 1856 
 May 23, 1856 
 May 23, 1856 
 April 15, 1857 
 May 27, 1857 
 June 27, 1S57 
 Aug. 16, 1857 
 Sept. 15, 1857 
 Sept. 19,1857 
 Sept. 19, 1857 
 Oct. 4, 1857 
 Jan. 22, 1858 
 Feb. 4, 1858 
 April 4, 1858 
 Sept. 11, 1858 
 Sept. 11,1858 
 Sept. 9, 1859 
 Sept. 22,1859 
 March 24, 1860 
 Sept. 12, 1860 
 Sept. 15, 1860 
 Sept. 19,1860 
 Oct. 10, 1860 
 Feb. 10. 1861 
 March 2,1861 
 March 4, 1861 
 April 9, 1861 
 April 17,1861 
 April 20,1861 
 April 29,1861 
 May 5, 1861 
 May 29, 1861 
 Aug. 18, 1861 
 April 7, 1862 
 Aug. 29, 1862 
 Sept. 22,1862 
 Oct. 21, 1862 
 Nov. 12, 1862 
 March 15, 1863 
 Sept. 14, 1S63 
 May 2, 1864 
 Sept. 30,1864 
 Nov. 27,1864 
 April 26, 1865 
 Ang 25, 1865 
 Sept. 19, 1865 
 
 Luther 
 Goldsmidt.. 
 Luther 
 Chacornac.. 
 Chacornac.. 
 Goldsmidt.. 
 Goldsmidt.. 
 Pogson 
 Pogso-n . ... 
 Goldsmidt.. 
 Goldsmidt. . 
 Pogson 
 Luther 
 Goldsmidt.. 
 Goldsmidt. . 
 Ferguson . . . 
 Laurent 
 Goldsmidt.. 
 Luther 
 Goldsmidt.. 
 Searle 
 Goldsmidt.. 
 Luther 
 Luther .... 
 Chacornac.. 
 Ferguson... 
 Goldsmidt. . 
 Foster 
 De Gasparis 
 Tempel 
 Tempel 
 Tuttle 
 Payson 
 Luther 
 Schiaparelli 
 Goldsmidt. 
 Peters 
 
 Bilk. 
 Paris. 
 Bilk. 
 Paris. 
 Paris. 
 Paris. 
 ?aris. 
 Oxford. 
 Oxford. 
 Paris. 
 Paris. 
 Oxford. 
 Bilk. 
 Paris. 
 Paris. 
 Washington, D. C. 
 STismes. 
 Paris. 
 Bilk. 
 Paris. 
 Albany, N. Y. 
 Paris. 
 Bilk. 
 Bilk. 
 Paris. 
 Washington, D. 
 Paris. 
 Berlin. 
 Naples. 
 Marseilles. 
 Marseilles. 
 Cambridge, Mass. 
 Madras. 
 Bilk. 
 Milan. 
 Paris. 
 Clinton, N. Y. 
 Bilk. 
 Cambridge, Mass. 
 Marseilles. 
 Clinton, N. Y. 
 Copenhagen 
 Clinton, N. Y. 
 Bilk. 
 Ann Arbor, Mich. 
 Oxford. 
 Marseilles. 
 Bilk. 
 Naples. 
 Bilk. 
 Clinton, N. Y. 
 
 88 Leda 
 
 89. Laetitia 
 40. Harmonia . . 
 41. Daphne 
 42. Isis 
 43. Ariadue 
 44 Nvsa 
 
 45. Eugenia 
 46. Hestia 
 47. Aglaia 
 
 48. Doris 
 49. Pales 
 50. Virginia .... 
 51. Nemausa 
 52. Enropa 
 53. Calypso 
 54. Alexandra . . 
 55. Pandora ... 
 56. Melete 
 57. Mnemosyne 
 58. Concordia . . 
 59. Olympia 
 60. Echo 
 
 61 Danae 
 
 62. Erato 
 
 63. Ansonia 
 64. Angelina ... 
 65. Cybele 
 66 Maja 
 
 67. Aria 
 
 68. Leto 
 69. Hesperia 
 70. Panoptea 
 71. Feronia.... 
 72. Niobe ...... 
 73. Clytie 
 74. Galatea 
 75. Euiidice.... 
 76. Freia 
 77. Frigga 
 78. Diana 
 79. Eurynome. 
 80. Snppho. ... 
 81. Terpsichore 
 B2. Alcmene .. 
 83. Beatrix.., 
 84. Clio... 
 85 lo 
 
 Luther. 
 Tuttle 
 Tempel 
 Peters 
 M. D. Arvert 
 Peters 
 Luther 
 Watson 
 Pogson 
 Tempel 
 Luther 
 De Gasparis 
 Luther .... 
 Peters 
 
 
THE PRIMARY PLANETS JUPITER AND SATURN. 2H3 
 
 CHAPTER VII. 
 
 PRIMARY PLANETS JUPITER AND SATURN. 
 
 473. JUPITER is the largest of all the planets belonging to the 
 eolar system. It may be readily distinguished from the fixed 
 stars, by its peculiar splendor and magnitude ; appearing to the 
 naked eye almost as resplendent as Yenus, although it is more 
 than seven times her distance from the Sun. 
 
 When his right ascension is less than that of the Sun, he is 
 our morning star, and appears in the eastern hemisphere before 
 the Sun rises ; when greater, he is our evening star, and lingers 
 in the western hemisphere after the Sun sets. 
 
 Nothing can be easier than to trace Jupiter among the con- 
 stellations of the zodiac ; for in whatever constellation he is seen 
 to-day, one year hence he will be seen equally advanced in the 
 next constellation ; two years hence, in the next ; three years 
 hence, in the next, and so on ; being just a year, at a mean rate, 
 in passing over one constellation. 
 
 The exact mean motion of Jupiter in its orbit, is about one-twelfth of a degree in a day j 
 %'hich amounts to only 80 20' 32" in a year. 
 
 For 12 years to come, he will, at a mean rate, pass through 
 the constellations of the zodiac, as follows : 
 
 1867, Capricornus. 
 1863, Aquarius. 
 
 1869, Pisces. 
 
 1870, Aries. 
 
 1871, Taurus. 
 
 1872, Gemini. 
 
 1873, Cancer. 
 
 1874, Leo. 
 
 1875, Virgo. 
 
 1876, Libra. 
 
 1877, Scorpio. 
 
 1878, Sagittarius. 
 
 479. Jupiter is the next planet in the solar system above the 
 asteroids, and performs his annual revolution around the Sun in 
 nearly 12 of our years, at the mean distance of 495,000,000 of 
 miles ; moving in his orbit at the rate of 30,000 miles an hour. 
 
 The exact period of Jupiter's sidereal revolution is 11 years, 10 months, 17 days, 14 
 hours, 21 minutes, 25% seconds. His exact mean distance from the Sun is 495,533,837 
 miles ; consequently, the exact rate of his motion in his orbit, is 29,943 miles per hour 
 
 480. He revolves on an axis, which is nearly perpendicular to 
 the plane of his orbit, in 9 hours, 55 minutes, and 50 seconds ; 
 so that his year contains 10,471 days and nights ; each about 
 5 hours long. 
 
 His form is that of an oblate spheroid, whose polar diameter 
 
 478. Comparative size of Jupiter ? How distinguished from the fixed stars? When 
 morning star, &c. ? Is he easily traced ? 479. His position in the system? His peri- 
 odic time? Distance from the Sun ? Rate of motion? 480. Time of diurna. revolu- 
 tion? Pa-jition of axis? Length of his days? Number in his year ? His form Cau9<f 
 rf His obJateness ? Difference of equatorial and polar diameters ? The Earth ? 
 
234 ASTRONOMY. 
 
 is to its equatorial, as 16 to IV. He is therefore considerably 
 more flattened at the poles than any of the other planets, except 
 Saturn. This is caused by his rapid rotation on his axis ; for it 
 is an universal law that the equatorial parts of every body, 
 revolving on an axis, will be swollen out, in proportion to the 
 density of the body, and the rapidity of its motion. 
 
 The difference between the polar and equatorial diameters of Jupiter, exceeds 6000 
 miles. The difference between the polar and equatorial diameters of the Earth, is only 
 26 miles. Jupiter, even on the most careless view through a good telescope, appears to 
 be oval ; the longer diameter being parallel to the direction of his belts, which are also 
 parallel to the ecliptic. 
 
 481. By this rapid whirl on its axis, his equatorial inhabitants 
 are carried around at the rate of 26,554 miles an hour ; which 
 is 1600 miles farther than the equatorial inhabitants of the 
 Earth are carried, by its diurnal motion, in twenty-four hours. 
 
 The true mean diameter of Jupiter is 88,780 miles ; which 
 is nearly 11 times greater than the Earth's. His volume is, 
 therefore, about thirteen hundred times larger than that of thr> 
 Earth. ( For magnitude as compa?'ed with that of the Earth, set 
 Map I.) On account of his great distance from the Sun, the 
 degree of light and heat which he receives from it is 27 times 
 less than that received by the Earth. 
 
 ; When Jupiter is in conjunction, he rises, sets, and comes to the meridian wit* the Sun ; 
 but is never observed to make a transit, or pass over the Sun's disc ; when in opposition, 
 he rises when the Sun sets, sets when the Sun rises, and comes to. the meridian at mid- 
 night, which never happens in the case of an interior planet. This proves that Jupiter 
 revolves in an orbit which is exterior to that of the Earth. 
 
 482. As the variety in the seasons of a planet, and in the 
 length of its days and nights, depends upon the inclination of its 
 axis to the plane of its orbit, and as the axis of Jupiter has 
 little or no inclination, there can be no difference in his seasons, 
 on the same parallels of latitude, nor any variation in the length 
 of his days and nights. It is not to be understood, however, 
 that one uniform season prevails from his equator to his poles ; 
 but that the same parallds of latitude on each side of his equa- 
 tor, uniformly enjoy the same season, whatever season it may be. 
 
 About his equatorial regions there is perpetual summer ; and 
 at his poles everlasting winter ; but yet equal day and equal 
 night at each. This arrangement seems to have been kindly 
 ordered by the beneficent Creator ; for had his axis been inclined 
 to his orbit, like that of the Earth, his polar winters would have 
 been alternately a dreadful night of six years' darkness. 
 
 481. Motion at Jupiter's equator? His mean diameter? His volume? Li^ht and heatr 
 Does he ever transit the Sun? What proof that his orbit is exterior to that of tli ; Earth? 
 482. What of the seasons of Jupiter ? What apparent manifestation of Divine Wisdom? 
 
THE PRIMARY PLANETS JUPITER AND SATURN. 235 
 
 TELESCOPIC VIEW OF JUPITKK. 
 
 483. Jupiter, when 
 viewed through a 
 telescope, appears to 
 be surrounded by a 
 number of luminous 
 zones, usually termed 
 Idls, tnat frequently 
 extend quite around 
 him. These belts are 
 parallel not only to 
 each other, but, in 
 general, to his equa- 
 tor, which is also 
 nearly parallel to the 
 ecliptic. They are 
 
 subject, however, to considerable variation, both in breath and 
 number. Sometimes eight have been seen at once ; sometimes only 
 one, but more usually three. Dr. Herschel once perceived his 
 whole disc covered with small belts, though they are more 
 usually confined to within 30 of his equator, that is, to a zone 
 60 in width. 
 
 Sometimes these belts continue for months at a time with little 
 or no variation, and sometimes a new belt has been seen to form 
 in a few hours. Sometimes they are interrupted in their length ; 
 and at other times, they appear to spread in width, and run into 
 each other, until their breadth exceeds 5000 miles. 
 
 484. Bright and dark spots are also frequently to be seen in 
 the belts, which usually disappear with the belts themselves, 
 though not always, for Cassini observed that one occupied the 
 same position more than 40 years. Of the cause, of these vari- 
 able appearances, but little is known. They are generally sup- 
 posed to be nothing more than atmospherical phenomena, resulting 
 from, or combined with, the rapid motion of the planet upon its 
 axis. 
 
 Different opinions have been entertained by astronomers respecting the cause of these 
 belts and spots. By some they have been regarded as clouds, or as openings in the 
 atmosphere of the planet, while others imagine that they are of a more permanent 
 nature, and are the marks of great physical revolutions, which are perpetually agitating 
 and changing the surface of the planet. The first of these opinions sufficiently explains 
 the variations in the form and magnitude of the spots, and the parallelism of the belts. 
 
 483. How does Jupiter appear through a telescope? Where are his belts usually 
 een? Their number? Are they permanent? 484. What else seen upon Jupiter's 
 surface? Are they permanent? Is the cause of these phenomena well understood! 
 What different opinions? 
 
236 
 
 ASTRONOMY. 
 
 JPhe spot first observed by Cassini, in 1665, which has both disappeared and reappeared 
 in the &arue form and position for the space of 43 years, could not possibly be occasioned 
 by any a'imospherical variations, but seems evidently to be connected with the surface 
 f th* plauet. The form of the belt, according to some astronomers, may be accounted 
 Tor by supposing that the atmosphere reflects more light than the body of the planet, 
 und that the clouds which float in it, being thrown into parallel strata by the rapidity of 
 ,'ts diurnal motion, form regular insterstices, through which are seen its opaque body, or 
 any of the permanent spots which may come within the range of the opening. 
 
 TELESCOPIC VIEWS OF THE MOONS OF 
 JUPITER. ' 
 
 MOONS OF JUPITER. 
 
 485. Jupiter is attended by four satellites or moons 
 Ai'e easily seen with a common spy- 
 glass, appearing like small stars 
 
 near the primary. (See adjoining 
 cut.) By watching them for a few 
 evenings, they will be seen to change 
 their places, and to occupy different 
 positions. At times, only one or two 
 may be seen, as the others are 
 either between the observer and the 
 planet, or beyond the primary, or 
 eclipsed by his shadow. 
 
 486. The size of these satellites 
 is about the same as our moon, 
 except the second, which is a trifle 
 less. The first is about the distance 
 of our moon ; and the others, re- 
 spectively, about two, tbree, and 
 five times as far off. 
 
 They 
 
 COMPARATIVE DIST 
 
 4th. 
 
 3d. 
 
 OF JUPITER'S MOONS 
 2d. 1st. 
 
 487 Their periods of revolution are from 1 day 18 hours to 
 17 days, according to their distances. This rapid motion is 
 necessary, in order to counterbalance the powerful centripetal 
 force of the planet, and to keep the satellites from falling to his 
 surface. 
 
 485. How many moons has Jupiter ? How seen? Why not all seen at once? 436 
 their size? Distances? 487. Periods of Jupiter's satellites? Why so rapid? 
 
THE PRIMARY PLANETS JUPITER AND SATURN. 287 
 
 The magnitudes, distances, and periods of the moons of Jupiter are as follows: 
 
 Diameter in miles. Distance. Periodic times. 
 
 1st 2,500 280,000 1 day 19 hours. 
 
 2d .. ...2,200 440,000 8 " 12 " 
 
 8d 3,500 700,000 7 " 14 " 
 
 4th 2,890 1,200,000 6 " 16 " 
 
 488. The orbits of Jupiter's moons are all in or near the plane 
 of his equator ; and as his orbit nearly coincides with the eclip- 
 tic, and his equator with his orbit, it follows that, like our own 
 moon, his satellites revolve near the plane of the ecliptic. On 
 this account, they are sometimes between us and the planet, and 
 sometimes beyond him, and seem to oscillate, like a pendulum, 
 from their greatest elongation on one side to their greatest elon- 
 gation on the other. 
 
 489. Their direction is from west to east, or in the direction 
 their primary revolves, both upon his axis and in his orbit. From 
 the fact that their elongations east and west of Jupiter are nearly 
 the same at every revolution, it is concluded that their orbits 
 are but slightly elliptical. They are supposed to revolve on 
 their respective axis, like our own satellite, the moon, once dur- 
 ing every periodic revolution. 
 
 490. As these orbits lie near the plane of the ecliptic, they 
 have to pass through his broad shadow when in opposition to the 
 Sun, and be totally eclipsed at every revolution. To this there 
 is but one exception. As the fourth satellite departs about 3 
 from the plane of Jupiter's orbit, and is quite distant, it some- 
 times passes above or below the shadow, and escapes eclipse. But 
 such escapes are not frequent. 
 
 These moons are not only often eclipsed, but they often eclipse 
 Jupiter, by throwing their own dark shadows upon his disc. 
 They may be seen like dark round spots traversing it from side 
 to side, causing, wherever that shadow falls, an eclipse of the 
 Sun. Altogether, about forty of these eclipses occur in the sys- 
 tem of Jupiter every month. 
 
 491. The immersions and emersions of Jupiter's moons have 
 reference to the phenomena of their being eclipsed. Their 
 entrance, into the shadow is the immersion ; and their coming out 
 of it the emersion. 
 
 488. How are their orbits situated ? How satellites appear to move ? 489. Direction 
 ot secondaries? Form of orbits? How ascertained? What motion on axis? 4i)0. 
 What said of eclipses ? Of fourth satellite ? Of solar eclipses upon Jupiter ? Numoer 
 of solar and lunar? 491. What are the immersions and emersions of Jupiter's 
 noons? Are the immersions and emersions always visible from the Earth? Why not? 
 UJuatrate. 
 
238 ASTRONOMY. 
 
 ECLIPSES 3P JUPITER'S BOONS, EMERSIONS, ETC. 
 
 .' .-^3=~- ', 
 
 f/2z&\ 
 
 lj{ i 
 
 The above is a perpendicular view of the orbits of Jupiter's satellites. His oroad 
 shadow is projected in a direction opposite the Sun. At C, the second satellite is suffer- 
 ing an immersion, and will soon be totally eclipsed ; while at D, the first is in the act of 
 emersion, and will soon appear with its wonted brightness. The other satellites are seen 
 to cast their shadows off into space, and are ready in turn to eclipse the Sun, or cut off a 
 portion of his beams from the face of the primary. 
 
 If the Earth were at A in the cut, the immersion, represented at C, would be invisible ; 
 and if at B, the emersion at D could not be seen. So, also, if the Earth were exactly at 
 F, neither could be seen ; as Jupiter and all his attendants would be directly beyond the 
 Sun, and would be hid from our view. 
 
 492. The system of Jupiter may be regarded as a miniature 
 representation of the solar system, and as furnishing triumphant 
 evidence of the truth of the Copernican theory. It may also be 
 regarded as a great natural clock, keeping absolute time for the 
 whole world ; as the immersions and emersions of his satellites 
 furnish a uniform standard, and, like a vast chronometer hung 
 up in the heavens, enable the mariner to determine his longitude 
 upon the trackless deep. 
 
 By long and careful observations upon these satellites, astronomers have been able to 
 construct tables, showing the exact time when each immersion and emersion will take 
 place, at Greenwich Observatory, near London. Now suppose the tables fixed the time 
 for a certain satellite to be eclipsed at 12 o'clock at Greenwich, but we find it to occur at 
 t) o'clock, for instance, by our local time : this would show that our time was three hours 
 behind the time at Greenwich ; or, in other words, that we were three hours, or 45, west 
 of Greenwich. If our time was ahead of Greenwich time, it would show that we were 
 eaut of that meridian, to the amount of 15 for every hour of variation. But this method 
 of finding the longitude is less used than the "lunar method" (Art. 407), on account of 
 the greater difficulty of making the necessary observations. 
 
 403. By observations upon the eclipses of Jupiter's moons, as 
 compared with the tables fixing the time of their occurrence, it 
 was discovered that light had a progressive motion, at the rate 
 of about 200,000 miles per second. 
 
 This discovery may be illustrated by again referring to the preceding cut. In the year 
 1675, it was observed by Roemer, a Danish astronomer, that when the Earth was nearest 
 to Jupiter, as at E, the eclipses of his satellites took place 8 minutes 13 seconds sooner 
 than the mean time of the tables ; but when the earth was farthest from Jupiter, as at 
 F, the eclipses took place 8 minutes and 13 seconds laUr than the tables predicted, th? 
 entire difference being 16 minutes and 26 seconds. This difference of time he ascribed to 
 the progressive motion of light, which he concluded required 16 minutes and 26 seconda 
 to oross the earth's orbit from E to F. 
 
 492. How may the system of Jupiter be regarded ? What use of it made in navigation ? 
 Illustrate method? Is it much used ? 493. What discovery by observing 
 of Jupiter's moons? Explain theorocess? 
 
THE PRIMARY PLANETS JUPITER AND SATURN. "39 
 
 Tins progress may be demonstrated as follows : 16m. 26s.=9S6s. If the radius of tfco 
 Earth's orbit be 95,000,000 of miles, the diameter must be twice that, or 190,000,000. 
 Divide 190,000,000 miles by 986 seconds, and we have 192,697|^|- miles as the progress 
 of light in each second. At this rate, light would pass nearly eight times around the $;lobc 
 at every tick of the clock, or nearly 500 times every minute ! 
 
 494. Jupiter, when seen from his nearest satellite, appears a 
 thousand times larger than our Moon does to us, exhibiting on a 
 scale of inconceivable magnificence, the varying forms of a cres- 
 cent, a half moon, a gibbous phase, and a fall moon, every 42 
 hours. 
 
 SATUKN. 
 
 495. SATURN is situated between the orbits of Jupiter and 
 Uranus, and is distinctly visible to the naked eye. It may be 
 easily distinguished from the fixed stars by its pale, feeble, and 
 steady light. It resembles the star Fomalhaut, both in color 
 and size, differing from it only in the steadiness and uniformity 
 of its light. 
 
 From the slowness of its motion in its orbit, the pupil throughout the period of hie 
 whole life, may trace its apparent course among the stars, without any danger of mis- 
 take. Having once found when it enters a particular constellation, he may easily remem- 
 ber where he is to look for it in any subsequent year; because, at a mean rate, it is just 
 2} years in passing over a single sign or constellation. 
 
 Saturn's mean daily motion among the stars is only about 2', 
 the thirtieth part of a degree. 
 
 496. The mean distance of Saturn from the Sun is nearly 
 double that of Jupiter, being about 909,000,000 of miles. His 
 diameter is about 73,484 miles ; his volume, therefore, is eleven 
 hundred times greater than the Earth's. Moving in his orbit at 
 tho rate of 22,000 miles an hour, he requires 29^- years to com- 
 plete his circuit around the Sun : but Ms diurnal rotation on his 
 axis is accomplished in 10J hours. His year, therefore, is nearly 
 thirty times as long as ours, while his day is shorter by more 
 than one-half. His year contains about 25,150 of its own days, 
 which are equal to 10,759 of our days. 
 
 497. The surface of Saturn, like that of Jupiter, is diversified 
 with belts and dark spots. Dr. Herschel sometimes perceived 
 five belts on his surface ; three of which were dark and two 
 bright. The dark belts have a yellowish tinge, and generally 
 cover a broader zone of the planet than those of Jupiter. 
 
 To the inhabitants of Saturn, the Sun appears 90 times less than he appears at the 
 Earth ; and they receive from him only one ninetieth part as much light and heat. But 
 
 494. How does Jupiter appear from his nearest satellite ? 495. Situation of Saturn ? 
 flow distinguished? How trac-? His rate of motion in the heavens? 49G. Distance 
 rom th: Sun? Diameter? Volume? Rate of motion in orbit ? Periodic time? Diur 
 nal revolution? Days in his year? 497. Appearance of his surface? Belts 1 The 
 seen from Stitnrn* Light and he;vt of that pkinet? Estimated strength of the 
 
2-10 ASTRONOiMY. 
 
 it is computed that even the ninetieth part of the Sun's light exceeds the illuminating 
 power of 8000 full moons, which would be abundantly sufficient for all the purposes of 
 fife. 
 
 498. The telescopic appearance of Saturn is unparalleled. It 
 is even more interesting than Jupiter, with all his moons and 
 belts. That which eminently distinguishes this planet from 
 every other in the system, is a magnificent zone or ring, encir- 
 cling it with perpetual light. 
 
 The adjoining out is an excel- TELESCOPIC VIEW OF SATURN. 
 
 lent representation of Saturn 
 as seen through a telescope. 
 The oblateness of the planet is 
 easily perceptible, and his 
 shadow can be seen upon the 
 rings back of the planet. The 
 shadow of the rings may also 
 be seen running across his disc. 
 The writer has often seen the 
 opening between the body of 
 the planet and the interior 
 ring as distinctly as it appears 
 to the student in the cut. Un- 
 der very powerful telescopes, 
 these rings are found to be 
 again subdivided into an in- 
 definite number of concentric circles, one within the other, though this is considered 
 doubtful by Sir John Herschel. 
 
 499. The light of the ring is more brilliant than the planet 
 itself. It turns around its center of motion in the same time 
 that Saturn turns on its axis. When viewed with a good 
 telescope, it is usually found to consist of two concentric rings, 
 divided by a dark band. 
 
 It has been ascertained, however, that these rings are again subdivided; the third 
 division was distinctly seen by Prof. Encke, on the 25th of April, 1837, and also by Mr. 
 Lassel, on the 7th of September, 1843, at his observatory near Liverpool, England. Six 
 different rings were seen at Rome, in Italy, on the night of the 29th of May, 1833. And 
 more recent observations by Professor Bond, of Cambridge, have led to the conclusion 
 that, in all probability, these wonderful rings are^irf / It is well known that under tho 
 most powerful instruments they seem to be almost indefinitely subdivided. 
 
 500. As our view of the rings of Saturn is generally an 
 oblique one, they usually appear elliptical, and never circular. 
 The ellipse seems to contract for about 7^- years, till it almost 
 entirely disappears, when it begins to expand again, and con- 
 tinues to enlarge for 7 years, when it reaches its maximum of 
 expansion, and again begins to contract. For fifteen years, the 
 part of the rings toward us seems to be thrown up, while for tho 
 
 solar radiance? 498. Telescopic appearance of Saturn? For what distinguished': 
 499. Comparative light of his rings? Time of rotation around the planet? How does it 
 asuu'Jy appear? What further discoveries? 500. What the general apparent ligurt 
 of the rings? Why elliptical ? What periodic variat on of expansion ? Of inclination V 
 When nearly invisible? 
 
THE PRIMARY PLANETS JUPITER AND SATURN. 24! 
 
 next fifteen it appears to drop lelow the apparent center of the 
 planet ; and while shifting from one extreme to the other, the 
 rings become almost invisible, appearing only as a faint line of 
 light running from the planet in opposite directions. The ring? 
 vary also in their inclination, sometimes dipping to the right, 
 and at others to the left. 
 
 TELESCOPIC PHASES OP THE RINGS OP SATURN. 
 
 The above is a good representation of the various inclin-ations and degrees of expan 
 sion of the rings of Saturn, during his periodic journey of 80 years 
 
 PERPENDICULAR VIEW OF THE RINGS OF SATURN. 
 
 501. The rings of the 
 planet are always directed 
 more or less toward the 
 Earth, and sometimes ex- 
 actly toward us ; so that 
 we never see them perpen- 
 dicularly, but always either 
 exactly edgewise, or ob- 
 liquely, as shown in the last 
 figure. Were either pole 
 of the planet exactly toward 
 us, we should then have a 
 perpendicular view of the 
 rings, as shown in the ad- 
 joining cut. 
 
 502. The various phases of Saturn's rings are explained by 
 the facts that his axis remains parallel to itself (see following 
 cut), with an uniform inclination to the plane of his orbit, which 
 is very near the ecliptic ; and as the rings revolve over his 
 equator, and at right angles with his axis, they also remain 
 parallel to themselves. The revolution of the planet about the 
 Earth every 30 years, must therefore bring first one side of the 
 -ings to view, and then the other causing all the variations of 
 expansion, position, and inclination which the rings present. 
 
 fiOl. How are the rings situated with respect to the Earth? How would they f.ppenr i? 
 either pole of Saturn -were toward us? 5o2. How are the various phases of Saturn t 
 fings accounted for? 
 
242 
 
 ASTRONOMY. 
 
 8ATDRJJ AT BI-FFrrn,T POINTS IN III* ORBIT. 
 
 Here observe, first, that the axis of Saturn, like those of all the other planets, remans 
 permanent, OTJHiroUfi with itself; and as the rings are in the plane of his equator, and 
 at right angles with his axis, they also must remain parallel to themselves, whatever 
 position the planet may occupy in its orbit. 
 
 This being the case, it is obvious that while the planet is passing from A to E, the Sun 
 will shine upon the under or south, side of the rings ; and while he passes from E to -A 
 again, upon the upper or nortli side ; and as it requires about 30 years for the planet 
 to traverse these two semicircles, it is plain that the alternate day and night on the rings 
 will be 15 years each. 
 
 A and E are the equinoctial, and C and Q- the solstitial points in the orbit of Saturn. 
 At A and E the rings arc edgewise toward the Sun, and also toward the Earth, provided 
 Saturn is in opposition to the Sun. To an observer on the Earth, the rings will seem to 
 expand from A to C, and to contract from C to E. So, also, from E to G, and from G to 
 A. Again : from A to E the front of the rings will appear above the planet's center, and 
 from E to A below i f .. 
 
 The rings of Saturn were invisible, as rings, from the 22d of April, 1848, to the 19th of 
 January, 1S49. He came to his equinox September 7, 1848 ; from which time to February, 
 1856, his rings continued to expand. rom that time to June, 18(53, they contracted, 
 until he reached his other equinox at E. and the rinjrs became invisible. From Juno 
 18GS, to September, 1870, they will again expand ; and from September, 1870, to March, 
 1877, they will contract, when he will be at the equinox passed September 7, 1848, or 
 29 14 years before. 
 
 The writer has often seen the rings of Saturn in different stages of expansion, and con- 
 traction, and once when they were almost directly edgewise toward the Earth. At that 
 tune (January, 1849), they appeared as a bright line of light, as represented at A and 
 E, in the tirst cut on the preceding page. 
 
 503. The dimensions of the rings of Saturn may be stated in 
 round numbers as follows : 
 
 Miles. 
 
 Distance from the body of the planet to the first 
 
 ring 19,000 
 
 Width of interior ring 17,000 
 
 Space between the interior and exterior rings . . 2,000 
 
 Width of exterior ring 10,500 
 
 Thickness of the rings 100 
 
 b08. State the distances and dimensions of his rings, beginning at the body of the plnnrt, 
 K* '.Kissing outward? What additional statistics from licrschcl? 
 
THE PRIMAK1' PLAJNETS JUP1TEB. AND SATURN. 243 
 
 In c recent work, entitled " The New Theory of Creation and Deluge," it is predictor. 
 I*. at, at some future time, the fluid rings of Saturn may descend and deluge the pla.net, 
 >-.- ou s was deluged in the days of Noah. Sir David Brewster says : " Mr. Otto Strure 
 r, (i Mr. Bond have lately studied with the great Munich telescope at the Observatory 
 of 1'ulk.oway, the third ring of Saturn, which Mr. Dassels and Mr. Bond discovered to 
 be fl Jd. These astronomers are of opinion that this fluid ring is not of very recent 
 formation, and that it is not subject to rapid change , and they have come to the extra- 
 ord .jury conclusion that the inner border of the ring has, since the time of Huyprens, 
 bee i gradually approaching the body of Saturn, and that we may expect, sooner or 
 <ft( r, perhaps in some dozen of years, to see the rings united with the body of the planet." 
 
 M4. The rings of Saturn serve as reflectors to reflect the 
 HjrM of the Sun upon his disc, as our Moon reflects the light to 
 the Earth. In his nocturnal sky, they must appear like two 
 ffo^ereous arches of light, bright as 
 
 NIGHT SCHSB UPON SATORN. 
 
 rhc full moon, and spanning the 
 vhole heavens like a stupendous 
 rainbow. 
 
 In the annexed cut, the beholder is supposed 
 ro be situated some 30 north of the equator of 
 Saturn, and looking directly south. The skadow 
 of the planet is seen travelling up the arch as 
 the night advances, while a New Moon is shown 
 'n .the west, and a FiM Moon in the east at tho 
 same time. 
 
 505. The two rings united are nearly 13 times as wide as the 
 diameter of the Moon ; and the nearest is only y^th as far from 
 the planet as the Moon is from us. 
 
 The two rings united are 27,500 miles wide ; which-i-2160 the moon's diameter=12_7_ 
 3o 240,000 miles, the Moon's .distance + 19,000 the distance of Saturn's interior 
 ring=12ff. 
 
 At the distance of only 19,000 miles, our Moon would appear some forty times as large 
 as she does at her present distance. How magnificent and inconceivably grand, then, 
 must these vast rings appear, with a thousand tiuies the Moon's magnitude, and only 
 one-twelfth part of her distance ! 
 
 506. The periodic time of Saturn being nearly thirty years, 
 his motion eastward among the stars must be very slow, amount- 
 ing to only 12 a year, or one sign in 2 years. It will be easy, 
 therefore, having once ascertained his position, to watch his slow 
 progress eastward year after year, as he performs his vast circuit 
 around the heavens. 
 
 MOONS OF SATURN. 
 
 507. Besides the magnificent rings already described, th 
 telescope re veals eight satellites QI moons, revolving around Saturn. 
 But these are seen only with good instruments, and under favor- 
 able circumstances. 
 
 604. What purpose do the ring3 of Saturn serve? How appear in his evening sky? 
 605. Width of two rings, as compared with Moon ? Distance? Demonstrate both. How 
 would our Moon appear at the distance of Saturn's rings? 50(5. Eastward motion of 
 Saturn? Uow traced? 507. Muous of Saturn ? How seen? Best time for observing? 
 
 B.G. 11 
 
214 ASTRONOMY. 
 
 SATELLITES OF SATURH. 
 
 The best time for observ- 
 ing them is when the planet 
 is at his equinoxes, and his 
 rings are nearly invisible. 
 
 In January, 1849, the author saw five 
 
 of these satellites, as represented in the adjoining cut. The rings appeared only as a line 
 ->f light extending each way from the planet, and the satellites were in the direction of 
 the line, at different distances, as here represented 
 
 508. These satellites all revolve eastward with the rings of 
 the planet, in orbits nearly circular, and, with the exception of 
 the eighth, in the plane of the rings. Their mean distances, 
 respectively, ii*om the planet's center are from 123,000 to 
 2,366,000 miles ; and their periods from 22 hours to 79 days, 
 according to their distances. 
 
 The distances and periods of the satellites of Saturn are as follows : 
 
 Distance in mile*. Periodic time*. Distance in miles. Periodic times. 
 
 1st 118,000 day 22* hours 
 
 2d 152,000 1 " 9 
 
 8d 188,000 1 " 21 " 
 
 4th 240,000 2 "17 " 
 
 6th 886,000 4 days 12 hours 
 
 6th 778,000 15 " 22 " 
 
 7th 940,000 22 " .. "* 
 
 8th 2,263,000 79 " 7 " 
 
 COMPARATIVE DISTANCES OF THE MOONS OF SATURN. 
 
 509. The most distant of these satellites is the largest, sup 
 posed to be about the size of Mars ; and the remainder grow 
 smaller as they are nearer the primary. They are seldom eclipsed, 
 on account of the great inclination of their orbits to the ecliptic, 
 except twice in thirty years, when the rings are edgewise toward 
 the Sun, The eighth satellite, which has been studied more than 
 all the rest, is known to revolve once upon its axis during every 
 periodic revolution ; from which it is inferred that they all 
 revolve on their respective axis in the same manner. 
 
 SYSTEM OF SATURN NO ECLIPSES. 
 
 Let the line A B represent the plane 
 
 of the planet's orbit, C D his axis, and " 
 
 E F the plane of his rings. The satellites 
 being in the plane of the rings will 
 revolve around the shadow of the pri- 
 mary, instead of passing through it, and 
 being eclipsed. 
 
 At the time of his equinoxes, however, 
 when the rings are turned toward the 
 i<un (see A and E, cut, page 242) they 
 must be in the center of the shadow on 
 
 508. The revolutions? Shape and position of their orbits ? Distances from their prl 
 ttiary? 509. Comparative size? 
 
THE PRIMARY PLANETS JUPITER AND SATURN. 245 
 
 tiic opposite side ; and the moons, revolving in the plane of the rings, must pass through 
 the shadow at every revolution. The eighth, however, may sometimes escape, on account 
 of his departure from the plane of the rings, as shown in the cut. 
 
 510. The theory of the satellites of Saturn is less perfect than 
 than that of the satellites of Jupiter. The difficulty of observ- 
 ing their eclipses, and of measuring their elongations from their 
 primary, have prevented astronomers from determining, with 
 their usual precision, their mean distances and revolutions. But 
 of this we are certain : there is no planet in the solar system, 
 whose firmament presents such a variety of splendid and mag- 
 nificent objects as that of Saturn. 
 
 The various aspects of the seren moons, one rising above the horizon, while another is 
 setting, and a third approaching to the meridian ; one entering into an eclipse, and 
 another emerging from one ; one appearing as a crescent, and another with a gibbous 
 phase ; and sometimes the whole of them shining in the same hemisphere, in one bright 
 assemblage ! The majestic motion of the rings at one time illuminating the sky with 
 their splendor, and eclipsing the stars ; at another, casting a deep shade over certain 
 regions of the planet, and unveiling to view the wonders of the starry firmament, arc 
 scenes worthy of the majesty of the Divine Being to unfold, and of rational creatures to 
 contemplate. 
 
 Such displays of Wisdom and Omnipotence, lead us to conclude that the numerous 
 splendid objects connected with this planet, were not created merely to shed their luster 
 on naked rocks and barren sands; but that an immense population of intelligent being? 
 is placed in those regions, to enjoy the bounty, and adore the goodness, of their great 
 Creator. 
 
 CHAPTER VIII. 
 PRIMARY PLANETS. URANUS AND NEPTUNE. 
 
 511 . URANUS is the next planet in order from the Sun, beyond 
 or above Saturn. To the naked eye, it appears like a star of 
 only the 6th or 7th magnitude, and of a pale, bluish white ; but 
 it can seldom be seen, except in a very fine, clear night, and in 
 the absence of the Moon. Through a telescope, he exhibits a 
 small, round, uniformly illuminated disc, without rings, belts, 01 
 discernible spots. His apparent diameter is about 4", from 
 which he never varies much, owing to the smallness of our orbH 
 in comparison with his own. 
 
 510. Is the system of Saturn well understood? Why not? Of what are we sure? 
 What scenes must it present? To what conclusion must these phenomena had ua 
 511. Portion and appearance rf Uranus? Through a, telescooe ? 
 
246 ASTRONOMY. 
 
 -Sir John Herschel says he is without discernible spots, and yet in his :ablps h* lays 
 down the time of the planet's rotation (which could only be ascertained by the rotation 
 of spots upon the planet's disc;, at v% hours. This time is probably given on the 
 minority of Schroeter, and is marked as doubtful by Dr. Herschel. 
 
 512. The motion of Uranus in longitude is still slower than 
 that of Saturn. It moves over but one degree of its orbit in 
 85 days ; hence he will be seven years in passing over one sign 
 or constellation. His periodic time being 84 years 27 days, his 
 eastward motion can amount to only about 4 17' in a whole 
 year. To detect this motion requires instruments and close 
 observations. At this date (1866), Uranus has made the entire 
 circuit of the heavens since his discovery in 1781; having 
 passed, in 1865, the point where he was first seen, and being 
 now upon his second known journey around the heavens. 
 
 It is remarkable that this body was observed as far back as 1690. It was seen three 
 times by Flamstead, once by Bradley, once by Mayer, and eleven times by Lemonnier, 
 who registered it among the stars ; but not one of them suspected it to be a planet. 
 
 513. The inequalities in the motions of Jupiter and Saturn, 
 which could not be accounted for from the mutual attractions 
 of these planets, led astronomers to suppose that there existed 
 another planet beyond the orbit of Saturn, by whose action 
 these irregularities were produced. This conjecture was con- 
 firmed March 13th, 1781, when Dr. Herschel discovered the 
 motions of this body, and thus proved it to be a planet. 
 
 514. The mean distance of Uranus from the Sun is 
 1,828,000,000 of miles ; more than twice the mean distance of 
 Saturn. His sidereal revolution is performed in 84 years and 
 1 month, and his motion in his orbit is 15,600 miles an hour. 
 He is supposed to have a rotation on his axis, in common with 
 the other planets ; but astronomers have not yet been able to 
 obtain any ocular proof of such a motion 
 
 515. His diameter is estimated at 36,000 miles ; which would 
 make his volume more than 80 times larger than the Earth's. 
 To his inhabitants, the Sun appears only the ^j part as large 
 as he does to us ; and of course they receive from him only that 
 small proportion of light and heat. It may be shewn, however, 
 that the ^-g part of the Sun's light exceeds the illuminating 
 power of 800 full moons. This, added to the light they must 
 receive from their six satellites, will render their days and 
 nights far from cheerless. 
 
 512. His motion in longitude ? Periodic time ? Angular motion per year ? How far 
 h.is he been traced since his discovery? When complete his revolution? Was he ever 
 ceen previous to !<;>..? By whom? Why are they not the discoverers, then ? 513. Was 
 his existence suspected previous to 1781 ? What ground for the suspicion? How prove J 
 to be a pifinet ? 514. Mean distance? Sid ereal revolution? Hourly motion in orbit t 
 Eolation on axis ? 515. Diameter ? V<riur- Light aod heat? ILie 
 
THE PRIMARY PLANETS URANUS AND NEPTUNE. 247 
 
 516. Uranus is attended by six moons or satellites, which 
 revolve about him in different periods, and at various distances. 
 Four of them were discovered by Sir William Herschel, and two 
 by his sister, Miss Caroline Herschel. It is possible that others 
 remain yet to be discovered. 
 
 Most of the satellites revolve from east to west around their 
 primaries; but the satellites of Uranus are an exception to this 
 rule. Their orbits are inclined to the plane of the ecliptic 79, 
 being little less than a right angle; and their motion in their 
 orbits is retrograde, that is, from east to west. 
 
 The distance from the planet, and the periodic times of the satellites of Uranus* 
 respectively, are as follows: 
 
 Dlst in mile*. Periodic tinier Dist in milot. Periodic times. 
 
 D. H. Tt. H. 
 
 1 120,000 2 1214... 380,000 18 11 
 
 2 171,000 4 85 777,000 38 2 
 
 8 288,000 8 1716 1,556,000 107 16 
 
 NEPTUNE. 
 
 517 This is the most distant of the primary planets, and in 
 some respects one of the most interesting. It is about 35,000 miles 
 in diameter, is situated at the mean distance of 2,862,000,000 
 miles from the Sun, and revolves around him in 164 years. So 
 remote is this newly-discovered member of the solar system, that 
 for a body to reach it, moving at railroad speed, or 30 miles an 
 hour, would require more than twenty thousand years ! 
 
 518. The circumstances of the discovery of this planet are at 
 once interesting and remarkable. Such is the regularity of the 
 planetary motions, that astronomers are enabled to predict, with 
 great accuracy, their future places in the heavens, and to con- 
 struct tables, exhibiting their positions for ages to come. Soon 
 after the discovery, of Uranus, in 1781, his orbit was computed, 
 and a table constructed for determining his future positions in 
 the heavens, but instead of following the prescribed path, or 
 occupying his estimated positions, he was found to be yielding to 
 some mysterious and unaccountable influence, under which he 
 was gradually leaving his computed orbit, and failing to meet 
 conditions of the tables. 
 
 510. Number of Moons? By whom discovered? Is it certain that Uranus hus six 
 satellites? Why doubtful? 517. Distance and diameter of Neptune? Period? How 
 long to pass from the Sun to it at railroad speed ? 518. What remarkable ircm 
 Stances respecting its discovery ? Perturbation ? 
 
248 ASTRONOMY. 
 
 519. At first this discrepancy between the observed and the 
 estimated places of Uranus, was charged upon the tables, and a 
 new orbit and new tables were computed, which it was thought 
 could not fail to represent the future places of the planet. But 
 these also seemed to be erroneous, as it was soon discovered tha t 
 the computed and observed places did not agree, and the differ- 
 ence was becoming greater and greater every year. This was 
 an anomaly in the movements of a planetary body. It was not 
 strange that it should be subject to perturbations, from the attrac- 
 tive influence of the large planets Jupiter arid Saturn, as these 
 were known to act upon him, as well as upon each other, and 
 the smaller planets, producing perturbations in their orbits, but 
 all this had been taken into the account in constructing the 
 tables, and still the planet deviated fi*>m its prescribed path. 
 
 520. To charge the discrepancy to the tables, was no longer 
 reasonable, though it was thought perhaps sufficient allowance 
 had not been made, in their computation, for the disturbing influ- 
 ence of Jupiter and Saturn. To determine this question, M. Le- 
 verrier, of Paris, undertook a thorough discussion of the sub- 
 ject, and soon ascertained that the disturbing influence upon 
 Uranus of all the known planets, was not sufficient to account 
 for the anomalous perturbations already described, and that they 
 were probably caused by some unknown planet, revolving beyond 
 the orbit of Uranus. From the amount and effect of this dis- 
 turbing influence from an unknown source, the distance, magni- 
 tude? and position of the imaginary planet were computed. 
 
 521. At this stage of the investigation, Leverrier wrote to 
 his friend, Dr. Galle, of Berlin, requesting him to direct his 
 telescope to that part of the heavens in which his calculations 
 had located the new planet, when lo 1 there he lay, a thousand 
 millions of miles beyond the orbit of Uranus, and yet within less 
 than one degree of the place pointed out by Leverrier ! This 
 was on the 1st of September, 1846. 
 
 522. While M. Leverrier was engaged in his calculations at 
 Paris, Mr. Adams, a young mathematician of Cambridge, Eng- 
 land, was discussing the same great problem, and had arrived at 
 similar results even before M. Leverrier, though entirely igno- 
 rant of each other's labors or conclusions. This seems to estab- 
 
 519. To what attributed at first? What done to correct? What then? 520. What 
 next undertaken, and by whom ? What result and conclusion ? 521. What remarkable 
 computation and letter? Result of Dr. Galle's search? 522. Who else investigating 
 the subject at the same time? His conclusions ? What fact does this establish? Why 
 not Adorns the discoverer? 
 
THE PRIMARY STARS SATURN AND NEPTU^ii. 249 
 
 Hsh the fact, that the new planet was discovered by calculation, 
 though' the failure of Mr. Adams to publish his conclusions, cut 
 off his right to the honor of the discovery. 
 
 523. Since the discovery of this planet, it has been ascertained 
 that it was seen as far back as 1795, though supposed to be a 
 fixed star, and catalogued as such ; and that all the irregulari- 
 ties of Uranus, with which astronomers were so much perplexed, 
 are perfectly accounted for by the influence of the new planet. 
 
 524. Neptune is attended by but one satellite, so far as is 
 known. It was discovered by Mr. Lassell, of Star-field, near 
 Liverpool, October 12, 1846. It revolves around its primary 
 in 5 days and 21 hours, at a distance of 236,000 miles from the 
 planet's centre. Its orbit is inclined to the plane of the ecliptic 
 29, and its motion in its orbit is retrograde, like the direction 
 of the satellites of Uranus. 
 
 CHAPTER IX. 
 
 OOMET^-THEIR NATURE, MOTIONS, ORBITS, &o. 
 
 525. COMETS, whether viewed as ephemeral meteors, or as 
 substantial bodies, forming a part of the solar system, are objects 
 of no ordinary interest. When, with uninstructed gaze, we look 
 upwards, to the clear sky of evening, and behold, among the 
 multitudes of heavenly bodies, one, blazing with its long train 
 of light, and rushing onward towards the center of our system, 
 we insensibly shrink back as if in the presence of a supernatural 
 being. But when, with the eye of astronomy, we follow it 
 through its perihelion, and trace it far off, beyond the utmost 
 verge of the solar system, till it is lost in the infinity of space, 
 not to return for centuries, we are deeply impressed with a sense 
 of that power which could create and set in motion such 
 bodies. 
 
 526. Comets are distinguished from the other heavenly bodies, 
 by their appearance and motion. The appearance of the planets 
 
 528. Has Neptune ever been seen prior to 1846? What supposed to be? Does it 
 account for the perturbation of Uranus? 524. lias Neptune a satellite? When, and 
 by whom discovered? What said of rings? 525. Subject of this chapter? How 
 jotneto regar led by the uninstructed? By the astronomer? 526. How distinguishe-J 
 
250 ASTRONOMY. 
 
 is globular, and their motion around the Sun is nearly in the 
 same plane, and from west to east ; but the comets have 
 variety of forms, and their orbits are not confined to any par- 
 ticular part of the heavens ; nor do they observe any one general 
 direction. 
 
 The orbits of the planets approach nearly to circles, while 
 those of the comets are very elongated ellipses. A wire hoop, 
 for example, will represent the orbit of a planet. If two oppo- 
 site sides of the same hoop be extended, so that it shall be long 
 and narrow it will then represent the orbit of a comet. Tho 
 Sun is always in one of the foci of the comet's orbit. 
 
 ORBIT 0V A OOMKT. 
 
 Here it will be seen that the orbit is very eccentric, that the perihelion point is very 
 near the Sun, and the aphelion point very remote. 
 
 There is, however, a practical difficulty of a peculiar nature which embarrasses the 
 solution of the question as to the form of the cometary orbits. It so happens that the 
 only part of the course of a comet which can ever be visible, is a portion throughout 
 which the ellipse, the parabola, and hyperbola, so closely resemble each other, that no 
 observations can be obtained with sufficient accuracy to enable us to distinguish them. 
 In fact, the observed path of any comet, while visible, may belong either to an ellipse, 
 parabola, or hyperbola. 
 
 527. That part which is usually brighter, or more opaque, than 
 the other portions of the comet, is called the nucleus. This is 
 surrounded by an envelope, which has a cloudy, or hairy appear- 
 ance. These two parts constitute the body, and, in many 
 instances, the whole of the comet. Most of them, however, are 
 attended by a long train, called the tail ; though some are with- 
 out this appendage, and as seen by the naked eye, are not easily 
 distinguished from the planets. Others again, have no apparent 
 nucleus, and seem to be only globular masses of vapor. 
 
 Nothing is known with certninty of the composition of these bodies. The envelope 
 appears to be nothing more than vapor, becoming more luminous and transparent when 
 
 trom other bodies? Form? Orbits? What practical difficulty mentioned? 527. 
 What is the nucleus of a comet? The envelope ? The tail? Have all cornets thes* 
 three parts? Do we understand of what they are composed? What evidence of then 
 <vxtreme tenuity? 
 
COMETS THEIR NATURE, MOTIONS, ORBITS, ETC. 251 
 
 approaching the Sun. As the comets pass between us and the fixed stars, their envelope j 
 and tails are so thin, that stars of very small magnitude may be seen through them. 
 Some comets, hiving no nucleus, are transparent throughout their whole extent. 
 
 528. The nucleus of a comet sometimes appears opaque, and 
 it then resembles a planet. Astronomers, however, are not 
 agreed upon this point. Some affirm that the nucleus is always 
 transparent, and that comets are in fact nothing but a mass of 
 vapor, more or less condensed at the center. By others it is main- 
 tained that the nucleus is sometimes solid and opaque. It 
 seems probable, however, that there are three classes of comets, 
 viz. ; 1st. Those which have no nucleus, being transparent 
 throughout their whole extent ; 2d. Those which have a trans- 
 parent nucleus ; and, 3d. Those having a nucleus which is solid 
 and opaque. 
 
 529. A comet, when at a distance from the Sun, viewed 
 through a good telescope, has the appearance of a dense vapor 
 surrounding the nucleus, and sometimes flowing far into the 
 regions of space. As it approaches the Sun, its light becomes 
 more brilliant, till it reaches its perihelion, when its light is more 
 dazzling than that of any other celestial body, the Sun excepted. 
 In this part of its orbit are seen to the best advantage the phe- 
 nomena of this wonderful body, which has, from remote antiquity, 
 been the specter of alarm and terror. 
 
 530. The luminous train of a comet usually follows it, as it 
 approaches the Sun, and goes before it, when the comet recedes 
 from the Sun ; sometimes the tail is considerably curved towards 
 the region to which the comet is tending, and in some instances, 
 it has been observed to form a right angle with a line drawn 
 from the Sun through the center of the comet. The tail of the 
 comet of 1744, formed nearly a quarter of a circle ; that of 
 1689 was curved like a Turkish sabre. (Map IX., Fig. 73.) 
 Sometimes the same comet has several tails. That of 1744 had, 
 at one time, no less than six, which appeared and disappeared in 
 a few days. (See Map IX., Fig. 74.) The comet of 1823 
 had, for several days, two tails ; one extending towards the Sun, 
 and the other in the opposite direction. 
 
 531. Comets, in passing among and near the planets, are ma- 
 terially drawn aside from their courses, and in some cases have 
 their orbits entirely changed. This is remarkably true in regard 
 
 528. What difference of opinion respecting t'e nucleus of comets? What probable 
 
 solution ? 529. How do they appear when viewed through a telescope at a distance 
 
 from the Sun? As it approaches him? Where seen to best advantage? 530. UsufiJ 
 
 lirection of the trains of comets? Other positions? Comet of 1744? Of Ib89? O/ 
 
 S23? 531. Influence of attraction upon comets? Illustrations? Comet of 1770 ? 
 
252 ASTRONOMY. 
 
 to Jupiter, which seems by some strange fatality to be constantly 
 in their way, and to serve as a perpetual stumbling-block to 
 them. 
 
 " The remarkable comet of 1770, which was found by Lexell to revolve in a moderate 
 ellipse, in a period of about five years, actually got entangled among the satellites of 
 Jupiter, and thrown out of its orbit by the attractions of that planet," and has not been 
 heard of since. fferschel, p. 310. By this extraordinary rencontre, the motions of 
 Jupiter's satellites suffered not the least perceptible derangement ; a sufficient proof of 
 the aeriform nature of the comet's mass. 
 
 532. It is clear from observation, that comets contain very 
 little matter. For they produce little or no effect on the motion 
 of the planets when passing near those bodies ; it is said that a 
 comet, in 1454, eclipsed the Moon ; so that it must have been 
 very near the Earth ; yet no sensible effect was observed to be 
 produced by this cause, upon the motion of the Earth or the 
 Moon. 
 
 The observations of philosophers upon comets, have as yet detected nothing of their 
 nature. Tycho Brahe and Appiar. supposed their tails to be produced by the rays of the 
 Sun transmitted through the nucleus, which they supposed to be transparent, and to ope- 
 rate as a lens. Kepler thought they were occasioned by the atmosphere of the comet, 
 driven off by the impulse of the Sun's rays. This opinion, with some modification, was 
 also maintained by Euler. Sir Isaac Newton conjectured that they were a thin vapor, 
 rising from the heated nucleus, as smoke ascends from the Earth ; while Dr. Hamilton 
 
 supposed them to oe streams of electricity. 
 "That the luminous part of a comet," s 
 
 says Sir John Herschel, " is something in the 
 nature of a smoke, fog, or cloud, suspended in a transparent atmosphere, is evident from 
 a fact which has been often noticed viz., that the portion of the tail where it comes up 
 to, and surrounds the head, is yet separated from it by an interval less luminous ; as we 
 often see one layer of clouds laid over another with a considerable clear space between 
 them." And again : " It follows that these can only be regarded as great masses of thin 
 vapor, susceptible of being penetrated through their whole substance by the sunbeams." 
 
 533. Comets have always been considered by the ignorant and 
 superstitious, as the harbingers of war, pestilence, and famine. 
 Nor has this opinion been, even to this day, confined to the 
 unlearned. It was once universal. And when we examine the 
 dimensions and appearances of some of these bodies, we cease 
 to wonder that they produced universal alarm. 
 
 According to the testimony of the early writers, a comet which could be seen in day- 
 light with the naked eye, made its appearance 43 years before the birth of our Saviour. 
 This date was just after the death of Caesar, and by the Romans, the comet was believed 
 to be his metamorphosed soul, armed with fire and vengeance. This comet is again men- 
 tioned as appearing in 1106, and then resembling the Sun in brightness, being of a great 
 eize, and having an immense tail. In the year 1402, a comet was seen, so brilliant as to 
 be discerned at noon-day. 
 
 534. In 1456, a large comet mads its appearance. It spread 
 a wider terror than was ever known before. The belief was very 
 general, among all classes, that the comet would destroy the 
 Earth, and that the Day of Judgment was at hand I 
 
 632. What said of their ] hysical natures ? Opinion of Tycho Brahe ? Of Kepler and 
 Euler? Of Newton and Dr. Hamilton] Of Sir John Herschel? 633. How have corneta 
 Usually been regarded by :he ignorant? What remarkable comet mentioned? 53-t. 
 What comet in 145G ? EFact of its appearance ? Has it appeared since ? Its period ? 
 
COMETS THEIR NATURE, MOTIONS, ORBITS, ETC. 253 
 
 The same comet appeared again in the years 1531, 1607, 1682, 
 1758 and 1835. It passed its perihelion in November, 1835, 
 and will re-appear every 75^ years thereafter. 
 
 At the time of the appearance of this comet, the Turks extended their victorious arms 
 r,cror : 3 the Hellespont, and seemed destined to overrun all Europe. This added not a 
 .ittle to the general gloom. Under all these impressions, the people seemed totally regard- 
 less of the present, and anxious only for the future. The Romish Church held at this 
 time unbounded sway over the lives, and fortunes, and consciences of men. To prepare 
 the world for its expected doom, Pope Calixtus III. ordered the Ave Maria to be repeated 
 three times a day, instead of two. He ordered the church bells to be rung at noon, 
 which was the origin of that practice, so universal in Christian churches. To the Avc 
 Maria, the prayer was added " Lord ! save us from the Devil, the Turk and the Comet ;" 
 and once, each day, these three obnoxious personages suffered a regular excommuni- 
 lation. , 
 
 The Pope and clergy exhibiting such fear, it is not a matter of wonder that it became 
 the ruling passion of the multitude. The churches and convents were crow 'ed for con- 
 fession of sins ; and treasures uncounted were poured into the Apostolic chau ber. 
 
 The comet, after suffering some months of daily cursing and excommunicati >n, began 
 to show signs of retreat, and soon disappeared from those eyes in which it i >und nc 
 favor. Joy and tranquillity soon returned to the faithful subjects of the Pope, bu not sc 
 their money and lands. The people, however, became satisfied that their lives, and the 
 safety of the world, had been cheaply purchased. The Pope, who had achieved so signal 
 a victory over the monster of the sky, had checked the progress of the Turk, and kept, 
 for the present, his Satanic majesty at a safe distance ; while the Church of Rome, 
 retaining her unbounded wealth, was enabled to continue that influence over her follow- 
 ers, which she retains, in part, to this day. 
 
 535. The cornet of 1680 would have been still more alarming 
 than that of 1456, had not science robbed it of its terrors, and 
 history pointed to the signal failure of its predecessor. This 
 comet was of the largest size, and had a tail whose enormous 
 length was more than ninety-six millions of miles. (Map IX.. 
 Fig. 75.) 
 
 At its greatest distance, it is 13,000,000,000 of miles from 
 the Sun ; and at its nearest approach, only 574,000 miles from 
 his center ;* or about 130,000 miles from his surface. In that 
 
 * In Brewster's edition of Ferguson, this distance is stated as only 49,000 miles. This 
 is evidently a mistake ; for if the comet approached the Sun's center within 49,000 miles, 
 it would penetrate 390,000 miles below the surface ! Taking Ferguson's own elements for 
 computing the perihelion distance, the result will be 494,460 miles. The mistake may be 
 accounted for, by supposing that the cypher had been omitted in the copy, and the period 
 pointed off one figure farther to the left. Yet, with this alteration, it would be still incor- 
 rect; because the Earth's mean distance from the Sun, which is the integer of this calcu- 
 lation, is assumed at 82,000,000 of miles. The ratio of the comet's perihelion distance 
 from the Sun, to the Earth's mean distance, as given by M. Pingre, is as 0.00603 to 1. 
 This multiplied into 95,213,869, gives 574,500 miles for the comet's perihelion distance 
 from the Sun's center; from which, if we substract his semi-diameter, 443,840 miles, we 
 shall have 130,660 miles, the distance of the comet from the surface of the Sun. 
 
 Again, if we divide the Earth's mean distance from the Sun, by the comet's perihelion 
 distance, we shall find that the latter is only l-166th part of the Earth's distance. Now 
 the square of 166 is 21,556 ; and this expresses the number of times that the Sun appears 
 larger to the comet, in the above situation, than it does to the Earth. Squire makes it 
 8-1,596 times larger. 
 
 According to Newton, the velocity is 880,000 miles per hour. More recent discoveries 
 indicate a velocity of 1,240,108 miles per hour. 
 
 Incidents respecting the Turks and Church of Rome ? 535. Comet of 1680 ? Length of 
 ito tail? Aphelion and perihelion distances? Rapidity of its motion when nearest the Sun? 
 What error corrected ? Appearance of the Fun from that point? Heat of tbe comet? 
 Indicates what? Fanciful theory of Dr. Whiston, and remarks upon it? 
 
254 ASTRONOMY. 
 
 part of its orbit which is nearest the Sun, it flies with the amaz- 
 ing swiftness of 1,000,000 miles in an hoar, and the Sun, as seen 
 from it, appears 27,000 times larger than it appears to us ; con- 
 sequently, it is then exposed to a heat 27,000 times greater than 
 the solar heat at the Earth. This intensity of heat exceeds, 
 several thousand times, that of red-hot iron, and indeed all the 
 degrees of heat that we are able to produce. A simple mass of 
 vapor, exposed to a thousandth part of such a heat, would be 
 at once dissipated in space a pretty strong indication that, 
 however volatile are the elements of which comets are composed, 
 they aro, nevertheless, capable of enduring an inconceivable 
 intensity of both heat and cold. 
 
 This < the comet which, according to the reveries of Dr. Whiston and others, deluged 
 the wo- id in the time of Noah. Whiston was the friend and successor of Newton ; but, 
 anxjf-us to know more than is revealed, he passed the bounds of sober philosophy, and 
 presumed not only to fix the residence of the damned, but also the nature of their punish- 
 ment. According to this theory, a comet was the awful prison-house in which, as it 
 wheeled from the remotest regions of darkness and cold into the very vicinity of the 
 ?un, hurrying its wretched tenants to the extremes of perishing cold and devouring fire, 
 the Almighty was to dispense the severities of his justice. Such theories may be ingenious, 
 but they have no basis of facts to rest upon. They more properly belong to the chimeras 
 of Astrology, than to the science of Astronomy. 
 
 536. When we are told by philosophers of great caution and 
 high reputation, that "the fiery train of the comet, just alluded 
 to, extended from the horizon to the zenith ; and that that of 
 1744 had, at one time, six tails, each 6,000,000 of miles long, 
 long, and that another, which appeared soon after, had one 
 40,000,000 of miles long, and when we consider also the incon- 
 ceivable velocity with which they speed their flight through the 
 solar system, we may cease to wonder if, in the darker ages, 
 they have been regarded as evil omens. 
 
 But these idle fantasies are not peculiar to any age or country. Even in our own 
 times, the beautiful comet of 1811, the most splendid one of modern times, was generally 
 considered among the superstitious, as the dread harbinger of the war which was 
 declared in the following spring. It is well known that an indefinite apprehension of a 
 more dreadful catastrophe lately pervaded both continents, in anticipation of Biela's 
 comet of 1832. 
 
 537. The nucleus of the corneN of 1811, according to observa- 
 tions made near Boston, was 2617 miles in diamete*, correspond- 
 ing nearly to the size of the Moon. The brilliancy with which 
 it shone, was equal to one-tenth of that of the Moon. The 
 envelope, or aeriform covering surrounding the nucleus, was 
 24,000 miles thick, about five hundred times as thick as the 
 atmosphere which encircles the Earth ; making the diameter of 
 comet, including its envelope, 50,617 miles. It had a very 
 
 530. Why not strange that these comets were regarded as evil omens ? Are such super- 
 stitions peculiar to any age or country? What illustrations? 537. Size of the co:ne/. 
 of 1S11? Its motion at its perihelion ? 
 
COMETS THEIR NATURE, MOTIONS, ORBITS, ETC. 255 
 
 luminous tail, whose greatest length was one hundred millions of 
 miles. Map IX., Fig. 16. This comet moved, in its perihelion, 
 with an almost inconceivable velocity fifteen hundred times 
 greater than that of a ball bursting from the mouth of a cannon. 
 
 538. According to Regiomontanus, the comet of 1472 moved 
 over an arc of 120 in one day. Brydone observed a comet at 
 Palermo in 1770, which passed through 50 of a great circle in 
 the heavens in 24 hours. Another comet, which appeared in 
 1759, passed over 41 in the same time. The conjecture of Dr. 
 Halley, therefore, seems highly probable, that if a body of such a 
 size, having any considerable density, and moving with such a 
 velocity, were to strike our Earth, it would instantly reduce it 
 to chaos, mingling its elements in ruin. 
 
 The transient effect of a body passing near the Earth, could scarcely amount to any 
 great convulsion, says Dr. Brewster ; but if the Earth were actually to receive a shock 
 from one of these bodies, " having any considerable density," the consequences would 
 indeed be awful. A new direction would be given to its rotary motion, and it would 
 revolve around a new axis. The seas, forsaking their beds, would be hurried, by their 
 centrifugal force, to the new equatorial regions ; islands and continents, the abodes of 
 men and animals, would be covered by the universal rush of the waters to the new 
 equator, and every vestige of human industry and genius would be at once destroyed. 
 But so far as we are as yet acquainted with these singular bodies, they are altogether too 
 light and gasseous to produce any such results by collision. 
 
 539. The chances against such an event, however, are so very 
 numerous, that there is no reason to dread its occurrence. The 
 French government, not long since, called the attention of some 
 of her ablest mathematicians and astronomers to the'solution of 
 this problem ; that is, to determine upon mathematical principles, 
 how many chances of collision the Earth was exposed to. After a 
 mature examination, they reported " We have found that, of 
 281,000,000 of chances, there is only one unfavorable there ex- 
 ists but one which can produce a collision between the two bodies." 
 
 "Admitting, then," say they, " for a moment, that the comets which may strike the 
 Earth with their nucleuses, would annihilate the whole human race; the danger of death 
 to each individual, resulting from the appearance of an unknown c<mi?t, would be 
 exactly equal to the risk he would run, if in an urn there was only one single white ball 
 among a total number of 281,000,000 balls, and that his condemnation to death would be 
 the inevitable consequence of the white ball being produced at the first drawing." 
 
 A little reflection, however, will show that all such fears are groundless. The same 
 unerring hand that guides the ponderous planet in its way, directs also the majestio 
 comet ; and where infinite wisdom and almighty power direct, it is almost profane to talk 
 of collision or accident. 
 
 540. We have before stated that comets, unlike the planets, 
 observe no one direction in their orbits, but approach to, and 
 recede from their great center of attraction, in every possible 
 
 633. Velocity of the comet of 1472? Of 17TO? Of 1759? Dr. Halley's conjecture? 
 Dr. Brewster's? Could a comet produce any such effects? 539. Is such a collision 
 probable? Why not? 540. What said of the orbits of comets and their various 
 directions ? 
 
25t5 ASTRONOMY. 
 
 direction. Nothing can be more sublime, or better calculated to 
 fill the mind with profound astonishment, than to contemplate the 
 revolution of comets, while in that part of their orbits which 
 comes within the sphere of the telescope. Some seem to come 
 up from the immeasurable depths below the ecliptic, and, having 
 doubled the heavens' mighty cape, again plunge downward with 
 their fiery trains, 
 
 " On the long travel of a thousand years." 
 
 Others appear to come down from the zenith of the universe 
 to double their perihelion about the Sun, and then reascend far 
 above all human vision. Others are dashing through the solar 
 system in all possible directions, and apparently without any 
 undisturbed or undisturbing path prescribed by Him who guides 
 and sustains them all. 
 
 541. Until within a few years, it was universally believed that 
 the periods of their revolutions must necessarily .be of prodigious 
 length ; but within a few years, two comets have been discov- 
 ered, whose revolutions are performed, comparatively, within 
 our own neighborhood. To distinguish them from the more 
 remote, they are denominated the Comets of a short period. The 
 first was discovered in the constellation Aquarius, by two French 
 astronomers, in the year 1786. The same comet was again 
 observed by Miss Caroline Herschel, in the constellation Cygnus, 
 in 1795, and again in 1805. In 1818, Professor Encke deter- 
 mined the dimensions of its orbit, and the period of its sidereal 
 revolution ; for which reason it has been called " Encke 's Comet. ' 
 Map IX., Fig. 77. 
 
 This comet performs its revolution around the Sun in about 3 years and 4 months, in 
 an elliptical orbit which lies wholly within the orbit of Jupiter. Its mean distance from 
 the Sun is 212,000,000 of miles; the eccentricity of its orbit is 179,000,000 of miles; con- 
 sequently, is 358,000,000 of miles nearer the Sun in its perihelion, than it is in its aphe- 
 lion. It was visible throughout the United States in 1825, when it presented a fine 
 appearance. It was also observed at its next return in 1828; but its return to its perihe- 
 lion on the 6th of May, 1832, was invisible in the United States, on account of its great 
 southern declination. It has returned at regular periods since that time. 
 
 542. The second " comet of a short period," was observed in 
 1772 ; and was seen again in 1805. It was not until its reap- 
 pearance in 1826, that astronomers were able to determine the 
 elements of its orbit, and the exact period of its revolution. 
 This was successfully accomplished by M. Biela of Josephstadt ; 
 hence it is called Bida j s Comet, 
 
 541. What opinion respecting their periods? What distinction in comets founded on 
 the .engths of their periods? History of u Encke 1 s Comet?" Its period, orbit, mean 
 iV.ance, eccentricity of its orbit? 542. History of " Bitla 'a Cometf" Its diameter V 
 
COMETS THEIR NATURE, MOTIONS, ORBITS, ETC. 257 
 
 According to observations made upon it in 1805, by the celebrated Dr. Olbers, its 
 diameter, including its envelope, is 42,280 miles. It is a curious fact, that the path of 
 Jiiela's Comet passes very near to that of the Earth ; so near, that at the moment the 
 center of the comet is at the point nearest to the Earth's path, the matter of the comet 
 extends beyond that path, and includes a portion within it. Thus, if the Earth were a4 
 that point of its orbit which is nearest to the path of the comet, at the same moment 
 that the comet should be at that point of its orbit which is nearest to the path of tho 
 Earth, the Earth would be enveloped in the nebulous atmosphere of the comet. 
 
 With respect to the effect which might be produced upon our atmosphere by such a 
 circumstance, it is impossible to offer anything but the most vague conjecture. Sir John 
 Herschel was able to distinguish stars as minute as the 16th or 17th magnitude through 
 th& l^ody of the comet 1 Hence it seems reasonable to infer, that the nebulous matter of 
 which it is composed, must be infinitely more attenuated than our atmosphere ; so that 
 for every particle of cometary matter which we should inhale, we should inspire millions 
 of particles of atmospheric air. 
 
 543 This is one of the comets that was to come into collision 
 with the Earth, and to blot it out from the Solar System. In 
 returning to its perihelion, November 26th, 1832, it was comput- 
 ed that it would cross the Earth's orbit at a distance of only 
 18,500 miles. It is evident that if the Earth had been in that 
 part of her orbit at the same time with the comet, our atmos- 
 phere would have mingled with the atmosphere of the comet, 
 and the two bodies, perhaps, have come in contact. But the 
 comet passed the Earth's orbit on the 29th of October, in the 
 8th degree of Sagittarius, and the Earth did not arrive at that 
 point un+il the 30th of November, which was 32 days after- 
 wards. 
 
 If we multiply the number of hours in 32 days, by 68,000 (the velocity of the Earth pel 
 hour), we shall find that the Earth was more than 52,000,000 miles behind the comet when 
 it crossed her orbit. Its nearest approach to the Earth at any time, was about 51,000,000 
 of miles ; its nearest approach to the Sun, was about 83,000,000 of miles. Its mean dis- 
 tance from the Sun, or half the longest axis of its orbit, is 387,000,000 of miles. Its 
 eccentricity is 253,000,000 of miles ; consequently, it is 507,000,000 of miles nearer the 
 Sun in its perihelion than it is in its aphelion. The period of its sidereal revolution is 
 2460 days, or about 6% days. 
 
 544. Although the comets of Encke and Biela are objects of 
 very great interest, yet their short periods, the limited space 
 within which their motion is circumscribed, and consequently the 
 very slight disturbance which they sustain from the attraction 
 of the planets, render them of less interest to physical astrono- 
 my thar those of longer periods. They do not, like them, rush 
 from the invisible and inaccessible depths of space, and, after 
 sweepirg our system, depart to distances with the conception of 
 which the imagination itself is confounded. They possess none 
 of that grandeur which is connected with whatever appears to 
 break through the fixed order of the universe. 
 
 What curious fact stated ? What result if the Earth were to be enveloped in the comet? 
 543. What mischief formerly anticipated from Biela's comet? Its return in 1882 V How 
 near a collision in distance and in time? Its nearest approach to the Earth ? To the 
 Sun? Its mean distance from him? Its eccentricity and period? 54-1. Why are the 
 c'.iuKs of short periods less interesting than others ? For what comet is it reserved to 
 9<*v.>- 1 grounds for the proudest triumph? of mathtuiatical science? 
 
258 ASTRONOMY. 
 
 It is reserved for the comet of Halley alone to afford the proudest triumphs to thowi 
 powers of calculation by which we are enabled to follow it in the depths of space, 
 ,000,000,000 of miles beyond the extreme verge of the solar system; and, notwithstand- 
 ing the disturbances which render each succeeding period of its return different from 
 the last, to foretell that return with precision. To be able to predict the very day and 
 circumstances of the return of such a bodiless and eccentric wanderer, after the lapse 
 of so many years, evinces a perfection of the astronomical calculus that may justly 
 challenge our admiration. 
 
 545. "The re-appearance of Biela's comet," says Herschel, 
 " whose return in 1832 was made the subject of elaborate cal- 
 culations by mathematicians of the first eminence, did not disap- 
 point the expectations of astronomers. It is hardly possible to 
 imagine anything more striking than the appearance, after the 
 lapse of nearly seven years, of such an all but imperceptible 
 cloud or wisp of vapor, true, however, to its predicted sime, and 
 place, and obeying laws like those which regulate the planets." 
 
 Herschel, whose Observatory was at Slough, England, observed the daily progress of 
 this comet from the 24th of September, until its disappearance, compared its actual posi- 
 tion from day to day, with its calculated position, and found them to agree within four 
 or five minutes of time in right ascension, and within a few seconds of declination. 
 Its position, then, as represented on a planisphere wnich the author prepared for his 
 pupils, and afterwards published, was true to within a less space than one-third of its 
 projected diameter. Like some others that have been observed, this comet has no lumi- 
 nous train by which it can be easily recognized by the naked eye, except when it is very 
 near the Sun. This is the reason why it was not more generally observed at its late 
 return. 
 
 Although this comet is usually denominated "Biela's comet," yet it seems that 
 M. Gambart, director of the Observatory at Marseilles, is equally entitled to the honor of 
 identifying it with the comet of 1772, and of 1805. He discovered it only 10 days after 
 Biela, and immediately set about calculating its elements from his own observations, which 
 are thought to equal, if they do not surpass, in point of accuracy, those of every other 
 astronomer. 
 
 546. Up to the beginning of the 17th century, HO correct 
 notions had been entertained in respect to the paths of comets. 
 Kepler's first conjecture was that they moved in straight lines ; 
 but as that did not agree with observation, he next concluded 
 that they were parabolic curves, having the Sun near the vertex, 
 and running indefinitely into the regions of space at both extre- 
 mities. There was nothing in the observations of the earlier 
 astronomers to fix their identity, or to lead him to suspect that 
 any one of them had ever been seen before ; much less that they 
 formed a part of the solar system, revolving about the Sun in 
 elliptical orbits that returned into themselves. 
 
 547. This grand discovery was reserved for one of the most 
 industrious and sagacious astronomers that ever lived this was 
 Dr. Halley, the cotemporary and friend of Newton. When the 
 comet of 1682 made its appearance, he set himself about observ- 
 ing it with great care, and found there was a wonderful resera- 
 
 545. Remarks on the re-appearance of Biela's comet? What remarkabl- calculation 
 referred to? Form of this comet? Is it really Biela's comet? 54C. Former kncw- 
 f the orbits of comets? 547. What .. _^u discovery, and by whom 9 Process 
 
CC-METS THEIR NATURE, MOTIONS, ORBITS, ETC 259 
 
 blance between it and three other comets that he found recorded, 
 the comets of 1456, of 1531, and 1607. The times of their 
 appearance had been nearly at equal and regular intervals ; their 
 perihelion distances were nearly the same ; and he finally proved 
 them to be one and the same comet, performing its circuit around 
 the Sun in a period varying a little from 76 years. It is, there- 
 fore, called Halky's comet. (Map IX., Fig. 78.) 
 
 The orbit of Halley's comet extends outward about 120,000,000 
 of miles beyond the orbit of Neptune, as represented in the fol 
 lowing cut : 
 
 ORBIT OF HALLKT'S COMET. 
 
 This is the same comet that filled the eastern world with so much consternation in 1456, 
 as stated on page 253, and became an object of such abhorrence to the Church of Rome. 
 
 The periodic times of the three comets just described, are as 
 follow : ' 
 
 Encke's, 1212 days. 
 Biela's, 2461 days. 
 Halley's, 28,000 days. 
 
 Halley's comet, true to its predicted time and place, is now (Oct. 1835) visible in the 
 evening sky. But we behold none of those phenomena which threw our ancestors of the 
 middle ages into agonies of superstitious terror. We see not the cometa JiorrendoB 
 magnitudinis, as it appeared in 1305, nor that tail of enormous length which, in 1456, 
 extended over two-thirds of the interval between the horizon and the zenith, nor even a 
 star as brilliant as was the same comet in 1682, with its tail of 30*. 
 
 Its mean distance from the Sun is 1,713,700,000 miles; the eccentricity of its orbit is 
 1,658,000,000 miles; consequently it is 3,316,000,000 miles farther from the Sun in its 
 aphelion than it is in its perihelion. In the latter case its distance from the sun is only 
 55,700,000 miles ; but in the former it is 3,371,700,000 miles. Therefore, thpugh its aphe- 
 lion distance be great, its mean distance is less than that of Uranus ; and great as is the 
 aphelion distance, it is but a very small fraction less than &n.e-Jive thousandth part of 
 that distance from the Sun, beyond which the very nearest of the fixed stars must be 
 situated ; and, as the determination of their distance is negative and not positive, the 
 nearest of them may be at twice or ten times that distance. 
 
 of the discovery? Aphelion distance of Halley's comet? What former visit to our sys- 
 tem referred to ? Periods of the three comets just described ? Appearance of Halley's 
 comet in 1835? Its mean distance from the Sun? How compare with that of Uranui t 
 Hov does his greatest distance compare with that of the Fixed Stars? 
 
260 ASTRONOMY. 
 
 548. The Orbit of Encke's OBBrra or SBVEBAL OOM*TB 
 
 comet is wholly within the orbit 
 of Jupiter, while that of Biela's 
 extends but a short distance 
 beyond it. The aphelion dis- 
 tance of Halley's comet is 
 3,400,000,000 of miles, or 
 050,000,000 of miles beyond 
 the orbit of Neptune. Aiid 
 even this is, in reality, a comet 
 of short period compared with 
 many that belong to our sys- 
 tem. 
 
 549. The comet of 1819 wasre- -"" "^ : - 
 markable for its straight wedge- 
 shaped appearance not altogether unlike a shuttle-cock. It 
 exhibited none of that curvature in its form which is an almost 
 universal characteristic of cometary bodies. Map IX., Fig. 79. 
 
 550. The comet of 1843 was one of the most magnificent of 
 modern times (See Map IX., Fig. 80). It was more than 60 
 in length. In the Southern Hemisphere it was so brilliant as 
 to throw a very strong light upon the Earth. As its distance 
 from the Sun varied, its color varied, from pale orange to "rose 
 red," and then to white. " It passed its perihelion on the 27th 
 of February, at which time it almost grazed the surface of the 
 Sun, approaching nearer to that luminary than any comet 
 hitherto observed. Its motions at this time were astonishingly 
 swift, and its brilliancy such as to induce the belief that it was at 
 a white heat through its whole extent. Its period is supposed 
 to be 21-J- years ; consequently this must be its eighth return 
 since 1668 ; and it will visit our sphere again in 1865." 
 
 At the time of the appearance of this comet, Rev. Mr. Miller and others were earnestly 
 warning the people of the United States, that the world was to be burned up on the 28<i 
 of April following ; and the appearance cf the comet was regarded by many as an indica- 
 tion that the end of all things was at hand. 
 
 551. The number of comets which have been observed since 
 the Christian era, amounts to 650. Scarcely a year has passed 
 without the observation of one or two. And since multitudes 
 of them must escape observation, by reason of their traversing 
 that part of the heavens which is above the horizon in the day 
 
 548. Where are the orbits of Encke's and Biela's comets situated? What said of Ral- 
 ly's comet? 549. Comet of 1819? 550. That of 1S43? Its length? Brilliancy? 
 What variation in its color ? Its perihelion passage ? Heat ? Its period ? Next appear- 
 ance? Incident of its last appearance? 551. Number of comets? Why so few sefn? 
 
COMETS THEIR NA1 URE, MOTIONS, ORBITS, ETC. 261 
 
 time, their whole number is probably many thousands. Comets 
 so circumstanced, can only become visible by the rare coinci- 
 dence of a total eclipse of the Sun a coincidence which hap- 
 pened, as related by Seneca, 60 years before Christ, wlen a 
 large comet was actually observed very near the Sun. 
 
 But M. Arago reasons in the following manner, with respect to the number of comets : 
 The number of ascertained comets, which, at their least distances, pass within the orbit 
 of Mercury, is thirty. Assuming that the comets are uniformly distributed throughout 
 the solar system, there will be 117,649 times as many comets included within the orbit of 
 Uranus, as there are within the orbit of Mercury. But as there are 30 within the orbit 
 of Mercury, there must be 3,529,470 within the orbit of Uranus ! 
 
 552. Of 97 comets whose elements have been calculated by 
 astronomers, 24 passed between the Sun and the orbit of Mer- 
 cury: 33 between the orbits of Mercury and Venus ; 21 between 
 the orbits of Venus and the Earth; 15 between the orbits of 
 Ceres and Jupiter. 49 of these comets move from east to west, 
 and 49 in the opposite direction. The total number of distinct 
 comets, whose paths during the visible part of their course had 
 been ascertained, up to the year 1855, was about one hundred 
 and fifty. 
 
 553. What regions these bodies visit, when they pass beyond 
 the limits of our view ; upon what errands they come, when 
 they again revisit the central parts of our .system ; what is the 
 difference between their physical constitution and that of the 
 Sun and planets ; and what important ends they are destined 
 to accomplish in the economy of the Universe, are inquiries 
 which naturally arise in the mind, but which surpass the limited 
 powers of the human understanding at present to determine. 
 
 554. Such is the celestial system with which our Earth was 
 associated at its creation, distinct from the rest of the starry 
 hosts. Whatever may be the comparative antiquity of our 
 globe, and the myriads of radiant bodies which nightly gem the 
 immense vault above us, it is most reasonable to conclude, that 
 the Sun, Earth, and planets differ little in the date of their 
 origin. This, fact, at least, seems to be philosophically certain, 
 that all the bodies which compose our solar system must have 
 been placed at one and the same time in that arrangement, and 
 in those positions in which we now behold them ; because all 
 maintain their present stations, and motions, and distances, by 
 their mutual action on each other. Neither could it be where it 
 
 Phenomenon 60 years before Christ? M. Arago's reasoning and conclusion? 552. 
 Perihelion distances of various comets ? Directions in longitude ? Number whose paths 
 have been ascertained? 553. What inquiries awakened by the visits of cometary 
 bodies? 5iJ4. Remarks respecting the date of the sola* system? What supposed p/oof 
 that the whole system was created at oucc? 
 
262 ASTRONOMY. 
 
 is, nor move as it does, nor appear as we see it, unless they 
 were all co-existent. The presence of each is essential to the 
 system the Sun to them, they to the Sun, and all to each 
 other. This fact is a strong indication that their formation waa 
 simultaneous. 
 
 CHAPTER X. 
 
 OF THE FORCES BY WHICH THE PLANETS ARE 
 RETAINED IN THEIR ORBITS. 
 
 555. HAVING described the real and apparent motions of tha 
 bodies which compose the solar system, it may be interesting 
 next to show, that these motions, however varied or complex 
 they may seem, all result from one simple principle, or law, 
 namely, the 
 
 LAW OF UNIVERSAL GRAVITATION. 
 
 By gravitation is meant, that universal law of attraction, by 
 which every particle of matter in the system has a tendency to 
 every other particle. This attraction, or tendency of bodies 
 towards each other, is in proportion to the quantity of matter 
 they contain. The Earth, being immensely large in "comparison 
 with all other substances in its vicinity, destroys the effect of 
 this attraction between smaller bodies, by bringing them all to 
 itself. 
 
 It is said, that Sir Isaac Newton, when he was drawing to a close the demonstration ol 
 the great truth, that gravity is the cause which keeps the heavenly bodies in their orbits, 
 was so much agitated with the magnitude and importance of the discovery he was about 
 to make, that he was unable to proceed, and desired a friend to finish what the intensity 
 of his feelings did not allow him to do. 
 
 556. The attraction of gravitation is reciprocal. All bodies 
 not only attract other bodies, but are themselves attracted, and 
 both according to their respective quantities of matter. The 
 Sun, the largest body in our system, attracts the Earth and all 
 the other planets, while they in turn attract the Sun. The 
 
 555. Subject of this chapter? What is meant by gravitation ? Upon what does the 
 amount of this attraction depend? Influence of the Earth? Anecdote of Newton? 
 N56. Is attraction reciprocal? What illustration cited? Ways in which attra< tiou 
 
LAW OF GRAVITATION. 263 
 
 Earth, also, attracts the, .Moon, and she in tnrn attracts the 
 Earth. A ball, thrown upwards from the Earth, is brought 
 again to its surface ; the Earth's attraction not only counter 
 balancing that of the ball, but also producing a motion of the 
 ball towards itself. 
 
 This disposition, or tendency towards the Earth, is manifested in whatever falls, whether 
 it be a pebble from the hand, an apple from a tree, or an avalanche from a mountain. 
 All terresual bodies, not excepting the waters of the ocean, gravitate towards the center 
 of the Earth, and it is by the same power that animals on all parts of the globe stand 
 with their feet pointing to its center. 
 
 557. The power of terrestial gravitation is greatest at the 
 Earth's surface, whence it decreases both upwards and down- 
 wards ; but not both ways in the same proportion. It decreases 
 upwards as the square of the distance, from the Earth's center 
 increases ; so that at a distance from the center equal to twice 
 the semi-diameter of the Earth, the gravitating force would be 
 only one-fourth of what it is at the surface. But below the sur- 
 face, it decreases in the direct ratio of the distance from the 
 center ; so that at a distance of half a semi-diameter from the 
 center, the gravitating force is but half of what it is at the 
 surface. 
 
 Weight and Gravity, in this case, are synonymous terms. We say a piece of lead 
 weighs a pound, or 16 ounces ; but if by any means it could be raised 4000 miles abovo 
 the surface of the Earth, which is about the distance of the surface from the center, and 
 consequently equal to two semi-diameters of the Earth above its center, it would weigh 
 only one-fourth of a pound, or four ounces ; and if the same weight could be raised to an 
 elevation of 12,000 miles above the surface, or four semi-diameters above the center of 
 the Earth, it would there weigh only one-sixteenth of a pound, or one ounce. 
 
 558. The same body, at the center of the Earth, being equally 
 attracted in every direction, would be without weight ; at 1000 
 miles from the center it would weigh one-fourth of a pound : at 
 2000 miles, one-half of a pound ; at 300 miles, three-fourths of 
 a pound ; and at 4000 miles, or at the surface, one pound. 
 
 It is a universal law of attraction, that its power decreases as 
 the square of the distance increases. The converse of this is also 
 true, viz.: The power increases as the square of the distance 
 decreases. Giving to this law the form of a practical rule, it will 
 stand thus : 
 
 The gravity of bodies above the surface of the Earth decreases 
 in a duplicate ratio (or as the squares of their distances), in semi- 
 diameters of the Earth, from the Earths center. That is, when 
 
 manifests itself? 55T. Where is the power of terrestrial gravitation greatest? How 
 iiminished ? In what ratio as we ascend above the Earth ? As we descend toward its 
 Center? Are weight and gravity the same ? 568. What would be the weight of a body 
 at the Earth's center? At 100 miles from th<? center ? At 2000 miles ? At 4000? What 
 universal iw? What rule based upon this law? What illustrations given? What ruU 
 
ASTRONOMY. 
 
 the gravity is increasing, multiply the weight by the square of 
 the distance ; but when the gravity is decreasing, divide, the 
 weight by the square of the distance. 
 
 Suppose a body weighs 40 pounds at 2000 miles above the Earth's surface, what would 
 It weigh at the surface, estimating the Earth's semi-diameter at 4000 miles. From tho 
 center to the given height, is 1J$ semi-diameters; the square of l>$,or 1.5 is 2.25, which, 
 multiplied into the weight (40), gives 90 pounds, the answer. 
 
 Suppose a body which weighs 256 pounds upon the surface of the Earth, be j-aised to 
 the distance of the Moon (240,000 miles), what would be its weight? Thus, 4000)240,000(60 
 semi-diameters, the square of which is 3600. As the gravity in this case is decreasing, 
 divide the weight by the square of the distance, and it will give 3600)256(1- 16th of a 
 pound, or 1 ounce. 
 
 To find to what height a given weight must be raised to lose a certain portion of its 
 weight. 
 
 RULE. Divide the weight at the surface by the required weight, and extract the 
 square root of the quotient. Ex. A boy weighs 100 pounds, how high must he be carried 
 to weigh but 4 pounds? Thus, 100 divided by 4, gives 25, the square root of which is 5 
 semi-diameters, or 20,000 miles above the center. 
 
 559. Bodies of equal magnitude do not always contain equal 
 quantities of matter ; a ball of cork, of equal bulk with one of 
 lead, contains less matter, because it is more porous. The Sun, 
 though fourteen hundred thousand times larger than the Earth, 
 being much less dense, contains a quantity of matter only 
 355,000 as great, and hence can exert an attractive iorce only 
 355,000 times greater than that which the Earth is capable of 
 exerting. 
 
 The quantity of matter in the Sun is 780 time? greater than that of all the plunets and 
 satellites belonging to the Solar System ; consequently, their whole united force of attrac- 
 tion is 780 times less upon the Sun, than that of the Sun upon them. 
 
 CENTER O? GRAVITY. 
 
 560. The Center of Gravity of a body, is that point in which 
 its whole weight is concentrated, and upon which it would rest, 
 if freely suspended. If two weights, one of ten pounds, the 
 other of one pound, be connected together by a rod eleven feet 
 long, nicely poised on a center, and then be thrown into a free 
 rotary motion, the heaviest will move in a circle with a radius of 
 one foot, and the lightest will describe a circle with a radius of 
 ten feet ; the center around which they move is their common 
 center of gravity. (See the Figure.) 
 
 to find what height a given weight must be raised to lose a certain portion of ita 
 weight? 55S). Do bodies attract in proptn-tion. to their bulk? Why not? What illua- 
 IrfttkMU? '(uantity of matter in the Sun? 6f>0. What is meant by the center cf 
 gravity f Illuairuiiuii? ilow with the Hun and pUuets? lluir would n be it ;hro w.u? 
 
ATTRACTIVE AND PROJECTILE FORCES. 205 
 
 Tims the Sun and planets move around in an imaginary point 
 as a center, always preserving an equilibrium. 
 
 If there were but one body in the universe, provided it were of uniform density, th< 
 nenter of it would be the center of gravity towards which all the surrounding portions 
 would uniformly tend, and they would thereby balance each other. Thus the center of 
 gravity, and the body itself, would for ever remain at rest. It would neither move up nor 
 down ; there being no other body to draw it in any direction. In this case, the terms up 
 aid down would have no meaning, except as applied to the body itself, to express the 
 direction of the surface from the center. 
 
 561. Were the Earth the only body revolving about the Sun, 
 as the Suu's quantity of matter is 355,000 times as great as 
 that of the Earth, the Sun would revolve in a circle equal onh 
 to the three hundred and fifty-five thousandth part of the Earth's 
 distance from it ; but as the planets in their several orbits vary 
 their positions, the center of gravity is not always at the same 
 distance from the Sun. 
 
 The quantity of matter in the Sun so far exceeds that of all 
 the planets together, that were they all on one side of him, he 
 would never be more than his own diameter from the common 
 center of gravity ; the Sun is, therefore, justly considered as the 
 center of the system. 
 
 562. The quantity of matter in the Earth being about 80 
 times as great as that of the Moon, their common center of 
 gravity is 80 times nearer the former than the latter, which is 
 about 3000 miles from the Earth's center. The secondary planets 
 are governed by the same laws as their primaries, and both 
 together movo around a common center of gravity. Ev^ry sys- 
 tem in the universe is supposed to revolve in like manner, around 
 one common center. 
 
 ATTRACTIVE AND PROJECTILE FORCES. 
 
 563. All simple motion is naturally rectilinear ; that is, all 
 bodies put in motion would continue to go forward in straight 
 lines, as long -as they met with no resistance or diverting force. 
 On the other hand, the Sun, from his immense size, would, by 
 the power of attraction, draw all the planets to nim, if his 
 attractive force were not counterbalanced by the primitive im- 
 pulse of the planetary bodies to move in straight lines. 
 
 564. The attractive power of a body drawing another body 
 
 but one body in the universe? 561. Suppose the Earth was the only body revolving 
 around the Sun? Is the center of gravity always at the same distance from the Sun? 
 Why not ? How would it be if all the planets were on one side of him? 562. What is 
 the amount of matter in the Earth as compared with the Moon? How with the second- 
 ary planets? With other systems in the universe? 563. What is the chaiacter of all 
 9>mi>le motion? What illustrations given ? 664 What is the attractive power called ? 
 
2(36 ASTRONOMY. 
 
 towards the center, is denominated Centripetal force ; and the ten* 
 dency of a revolving body to fly from the center in a tangent 
 line, is called the Projectile or Centrifugal force. The joint 
 action of these two central forces gives the planets a circular 
 motion, and retains them in their orbits as they revolve, the pri- 
 maries about the Sun, and the secondaries about their primaries. 
 565. The degree of the Sun's attractive power at each par* 
 tictflar planet, whatever be its distance, is uniformly equal to 
 the centrifugal force of the planet. The nearer any plane c is to 
 the Sun, the more strongly is it attracted by him ; the farther 
 any planet is' from the Sun, the less is it attracted by him ; 
 therefore, those planets which are the nearer to the Sun, must 
 move the faster in their orbits, in order thereby to acquire cen- 
 trifugal forces equal to the power of the Sun's attraction ; and 
 those which are the farther from the Sun, must move the slower, 
 in order that they may not have too great a degree of centri- 
 fugal force, for the weaker attraction of the Sun at those 
 distances. 
 
 LAWS OF PLANETARY MOTION. 
 
 566 Three very important laws, governing the movements of 
 the planets, were discovered by Kepler, a German astronomer, 
 in 1609 In honor of their discoverer, they are called Kepler' a 
 Laws. Kepler was a disciple of Tycho Brake, a noted astrono 
 mer of Denmark, and was equally celebrated 
 
 . 11* -i TT -\ - APHELION* 
 
 with his renowned tutor. His residence and ...- . x 
 
 observatory were at Wirtemburgh, in Ger- 
 many. 
 
 The first of these laws is, that the orbits of 
 nil the, planets are elliptical, having the Sun in 
 the common focus. 
 
 The point in a planet's orbit nearest the Sun is called the 
 perihelion point, and the point most remote the aphelion point. 
 Perihelion is from peri, about or near, and fielios, the Sun ; and 
 aphelion, from apo, from, and helio t the Sun. 
 
 PERIHELION. 
 
 From this first law of Kepler, it results that the planets move with different velocities, 
 in different parts of their orbits. From the aphelion to the perihelion points, the 
 centripetal force combines with the centrifugal to accelerate the planet's motion ; 
 while from perihelion to aphelion points, the centripetal acts against the centrifugal 
 force, and retdrcUi it. 
 
 The tendency to depart from the center? What does the joint action of these two forces 
 produce? 565. What relation between the Sun's attraction and the centrifugal force 
 of the planets? What effect has the distance of a planet from the Sun, upon his attrac- 
 tive force? How is this increased tendency counterbalanced? 566. What important 
 laws when and by whom discovered? State the first? What are the apf^lioii dnj 
 ts? Derivation? What results from this first law? 
 
LAWS OF PLANETARY MO11ON. 
 
 267 
 
 RADIUS VKCTOB. 
 
 From A to B in the diagram, the centrifugal force, 
 represented by the line C, acts with the tendency to 
 revolve, and the planet's motion is accelerated; but 
 from B to A the same force, shown by the line D, acts 
 against the tendency to advance, and the planet is 
 retarded. Hence it comes to aphelion with its least 
 Velocity, and to perihelion with its greatest. 
 
 In the statement of velocities on page 45, tbft mean 
 or average velocity is given. 
 
 567. The second law is, that the radius 
 vector of a planet describes equal areas in 
 equal times. The radius is an imaginary 
 Hue joining the center of the Sun and 
 the center of the planet, in any part of 
 its orbit. Vector is from veko, to carry ; 
 hence the radius vector is a radius carried 
 
 round. By the statement that it describes equal areas in equal 
 times, is meant that it sweeps over the same surface in an hour, 
 when a planet is near the Sun, and moves swiftly, as, when 
 furthest from the Sun, it moves mosfr slowly. 
 
 The nearer a planet is to the Sun, the more rapid its 
 motion. It follows, therefore, that if the orbit of a 
 planet is an ellipse, with the Sun in one of the foci, its 
 rate of motion will be unequal in different parts of its 
 orbit swiftest at perihelion, and slowest at aphelion. 
 From perihelion to aphelion the centripetal more di- 
 rectly counteracts the centrifugal force, and the planet 
 is retarded. On the other hand, from the aphelion to 
 the perihelion point, the centripetal and centrifugal 
 forces are united, or act in a similar direction. They 
 consequently hasten the planet onward, and its rate of 
 motion is constantly accelerated. Now suppose, when t 
 the planet is at a certain point near its perihelion, we 
 draw a line from its center to the center of the Sun. 
 This line is the radius vector. At the end of one day, 
 for instance, after the planet has advanced considera- 
 bly in its orbit, we draw another line in the same man- 
 ner to the Sun's center, and estimate the area between 
 the two lines. At another time, when the planet is near 
 its aphelion, we note the space over which the radius vector travels in one day, and esti- 
 mate its area. On comparison, it will be found, that notwithstanding the unequal 
 velocity of the planet, and consequently of the radius vector, at the two ends of the 
 :llipse, the area over which the radius vector has traveled is the same in both cases. 
 The same principle obtains in every part of the planetary orbits, whatever may be their 
 ellipticity or the mean distance of the planet from the Sun ; hence the rule that the 
 radius vector describes equal areas in equal times. In the preceding cut, the twelve 
 triangles, numbered 1, 2, 8, &c., over each of which the radius vector sweeps in equal 
 times, are equal. 
 
 568. The third law of Kepler is, that the squares of the periodic 
 times of any two planets are proportioned to the cubes of their mean 
 distances from the Sun. 
 
 Take, for example, the Earth and Mars, whose periods are 365-2564 and 686-9796 days, 
 and whose distances from the Sun are in the proportion of 1 to 1-52369, and it will be 
 found that (865.2564)2: (686.9796)-! :: (1)3 : (1.52369)3. 
 
 667. State the second law of Kepler? Explain it? 5C8. The third 'aw? What 
 illustration ? 
 
 B.G. 12 
 
}>68 ASTRONOMY. 
 
 
 
 According to these laws, which are known to prevail throughout the solar syotcai. 
 many of the facts of astronomy are deduced from other facts previously ascertained. 
 They are, therefore, of great importance, and should be studied till they are, at least, 
 thoroughly understood, if not committed to memory. 
 
 569. From the foregoing principles, it follows, that the force 
 of gravity, and the centrifugal force, are mutual opposing powers 
 
 each continually acting against the other. Thus, the weight 
 
 of bodies on the Earth's equator, is diminished by the centrifugal 
 force of her diurnal rotation, in the proportion of one pound for 
 every 290 pounds : that is, had the Earth no motion on her 
 axis, all bodies on the equator would weigh one two hundred and 
 eighty-ninth part more than they now do. 
 
 On the contrary, if her diurnal motion were accelerated, the centrifugal force would be 
 proportionally increased, and the weight of bodies at the equator would be in the same 
 ratio diminished. Should the Earth revolve upon its axis with a velocity which would 
 make the day but 84 minutes long, instead of 24 hours, the centrifugal force would coun- 
 terbalance that of gravity, and all bodies at the equator would then be absolutely desti- 
 tute of weight; and if the centrifugal force were further augmented (the Earth revolving 
 In less than 84 minutes), gravitation would be completely overpowered, and all fluids 
 and loose substances near the equator would fly off from the surface. 
 
 570. The weight of bodies, either upon the Earth, or on any 
 other planet having a motion around its axis, depends jointly 
 upon the mass of the planet, and its diurnal velocity. A body 
 weighing one pound upon the equator of the -Earth, would 
 weigh, if removed to the equator of the Sun, 27.91bs.; of Mer^ 
 cury, 1.03 Ibs.; of Venus, 0.98 Ibs.; of the Moon, l-6th of a-lb. ; 
 of Mars, | Ib. ; of Jupiter, 2.716 Ibs. ; of Saturn, 1.01 Ibs. 
 
 CHAPTER XI. 
 
 PKOPER MOTION OF THE SUN IN SPACE. 
 
 571. THOFGH we are accustomed to speak of the Sun as tho 
 fixed center of the Solar System, the idea of his fixedness is cor- 
 rect only so far as his relation to the bodies revolving around 
 him are concerned. As the planets accompanied by their satel- 
 lites revolve around the Sun, so he is found to be moving with 
 all his retinue of worlds, in a vast orbit, around some distant and 
 unknown center. 
 
 669. What results from these principles, as respects the weight of bodies on the Ekrth'a 
 surface? How increased or diminished? What illustrations given? 570. Upon 
 7 hat, then, does the weight of bodies upon the planets depend? What illustrations ? 
 CT1. la the Sun a fixed body? What motion in space? Who first advanced this idea? 
 
PROPER MOTION OF THE SUN IN SPACE. 269 
 
 This opinion was first advanced, we think, by Sir William Herschel; but the honor of 
 actually determining this interesting fact, belongs to Struve, who ascertained not only 
 .he direction of the Sun and Solar System, but also their velocity. The point of tend- 
 ency is towards the constellation Hercules, Right Ascension 259*, Declination 35*. The 
 velocity of the Sun, Ac., in space, is estimated at about 20,000 miles per hour, or uearly 
 S miles per second ; 
 
 572. With this wonderful fact in view, we may no longer con- 
 sider the Sun as fixed and stationary, but rather as a vast and 
 luminous planet, sustaining the same relation to some central 
 orb, that the primary planets sustain to him, or that the second- 
 aries sustain to their primaries. !Nor is it necessary that the 
 stupendous mechanism of nature should be restricted even to 
 these sublime proportions. The Sun's central body may also 
 have its orbit, and its center of attraction and motion, and so on, 
 till, as Dr. Dick observes, we come to the great center of all to 
 the THRONE OF GOD. 
 
 THE CENTRAL SUN. 
 
 573. In 1847, an article appeared in several European jour- 
 nals, announcing the probable discovery by Professor Madler, 
 of Dorpat, of the Sun's central orb ; the inclination of his orbit 
 to the plane, of the ecliptic ; and his periodic time ! 
 
 By an extensive and laborious comparison of the quantities 
 and directions of the proper motions of the stars in various parts 
 of the heavens, combined with indications afforded by the paral- 
 laxes hitherto determined, and with the theory of universal gra- 
 vitation, Professor Madler arrived at the conclusion that the 
 Pleiades form the central group of our whole astral or sidereal 
 system, including the Milky Way and all the brighter stars, but 
 exclusive of the more distant nebula?, and of the stars of which 
 those nebula? may be composed. And within this central group 
 itself he has been led to fix on the star Alcyone, as occupying 
 exactly or nearly the position of the center of gravity, and as 
 entitled to be called the central Sun. 
 
 Assuming Bessel's parallax of the star 61 Cygni, long since remarkable for its larger 
 proper motion, to be correctly determined, Madler proceeds to form a first approximate 
 estimate of the distance of this central body from the planetary or solar system ; and 
 arrives at the provisional conclusion, that Alcyone is about 34,000,000 times as far removed 
 from us, or from our own Sun, as the latter luminary is from us. It would, therefore 
 according to this estimation, be at least a million times as distant as the new planet, of 
 which the theoretical or deductive discovery has been so great and beautiful a triumph 
 of modern astronomy, and so striking a confirmation of the Jaw of Newton. The same 
 approximate determination of distance conducts to the result, that the light of the cen 
 tral sun occupies more than five centuries in travelling thence to us. 
 
 Direction and velocity of the Sun and Solar System ? 572. How, then, should w< 
 regard the Sun? What further speculation? Dr. Dick's observation? 573. What 
 great discovery in 1847, and by whom? By what process? What conclusion first 
 reached ? What star afterward designated ? Further description of the progress of the 
 discovery ? What conclusion respecting the passage of light from the sentral Sun to ua ? 
 
270 
 
 ASTRONOMY 
 
 , ., ARC OF THB SUN'S OBDIT 
 
 574. The enormous orbit 
 which our own Suu, with the 
 Earth, and the other planets, 
 is thus inferred to be describ- 
 ing about that distant cen- 
 ter not, indeed, under its 
 influence alone, but by the 
 combined attractions of all 
 the stars which are nearer to 
 it than we are, and which are 
 estimated to amount to more 
 than 117,000,000 of masses, 
 each equal to the total mass 
 of our own Solar System 
 is supposed to require upwards 
 of eighteen millions of years for 
 its complete description, at the rate of about eight geographical 
 miles in every second of time. At this rate, the arc of its orbit, 
 over which the Sun has traveled since the creation of the world, 
 amounts to only about ^o^th P ar * of m ' s orbit, or about t 
 minutes an arc so small, compared with the whole, as to be 
 hardly distinguishable from a straight line. 
 
 The plane of this vast orbit of the Sun is judged to have an inclination of about 84 
 degrees to the ecliptic, or to the plane of the annual orbit of the Earth ; and the longitude 
 of the ascending node of the former orbit on the latter is concluded to be nearly 232 
 degrees. 
 
 CHAPTER XII. 
 
 PRECESSION OF THE EQUINOXES OBLIQUITY OF THE 
 ECLIPTIC. 
 
 575. OF all the motions which are going forward in the Solar 
 System, there is none, which it is important to notice, more 
 difficult to comprehend, or to explain, than what is called the 
 
 PRECESSION OF THE EQUINOXES. 
 
 The equinoxes, as we have learned, are the two opposite 
 
 574. Supposed period of the Sun's revolution ? What portion of his orbit gone over 
 Jince the creation of our race? Situation of his orbit with respect to the ecliptic? Lon- 
 gitude of ascending node? 575. Subject of this chapter? What are the equinoxes ? 
 
PRECESSION OF THE EQUINOXES. 
 
 271 
 
 points in the Earth's orbit, where it crosses the celestial equator. 
 The first is in Aries ; the other, in Libra. By the precession of the 
 equinoxes is meant, that the intersection of the equator with the 
 ecliptic is not always in the same point : in other words, that 
 the Sun, in its apparent annual course, does not cross the equi- 
 noctial, Spring and Autumn, exactly in the same points, but 
 every year a little behind those of the preceding year. 
 
 576. This annual falling back of the equinoctial points, is 
 called by astronomers, with reference to the motion of the 
 heavens, the Precession of the Equinoxes; but it would better 
 accord with fact as well as the apprehension of the learner, to 
 call it, as it is, the Recession of the Equinoxes ; for the equinoc- 
 tial points do actually recede upon the ecliptic, at the ra>e of 
 about 50" of a degree every year. It is the name only, and 
 not the position, of the equinoxes which remains permanent. 
 Wherever the Sun crosses the equinoctial in the spring, there is 
 the vernal equinox ; and wherever he crosses it in the autumn, 
 there is the autumnal equinox \ and these points are constantly 
 moving to the west. 
 
 PRECESSION OF THE EQUINOXES. 
 
 To render this subject familiar, 
 we will suppose two carriage roads, 
 extending quite around the Earth; 
 one, representing the equator, run- 
 ning due east and west; and the 
 other representing the ecliptic, run- 
 ning nearly in the same direction as 
 the former, yet so as to cross it with 
 a small angle (say of 2333), both at 
 the point where we now stand, for 
 instance, and in the nadir, exactly 
 opposite ; let there also be another 
 road, to represent the prime meri- 
 dian, running north and south, and 
 erasing the first at right angles, in 
 the common point of intersection, as 
 in the annexed figure. 
 
 Let a carriage now start from this 
 point of intersection, not in the road 
 leading directly east, but along that 
 of the ecliptic, which leaves the 
 former a little to the north, and let 
 a person >>e placed to watch when 
 the carriage comes around again, 
 after having made the circuit of the 
 Earth, and see whether the carriage 
 will cross the equinoctial road again 
 precisely in the same track as when it left the goal. Though the person stood exactly 
 in the former track, he need not fear being run over, for the carriage will cross the 
 road 100 rods west of him, that is 100 rods west of the meridian on which he stood. It is 
 to be observed, that 100 rods on the equator is equal to 50 i seconds of a degree. 
 
 If the carriage still continue to go around the Earth, it will, on completing its second 
 
 What meant by their precession ? 576. With reference to what is it a preccf&ionf Id 
 it really a precession of the equinoxes ? Where are the equinoxes spring and fall ? Can 
 you illustrate by the two carriage roads, &c. ? By the other diagram? Does the >un 
 
272 
 
 ASTRONOMY. 
 
 RECESSION OF THE EQUINOXES. 
 
 circuit, cross the equinoctial path 200 rods west of the meridian whence it first set out 
 on the third circuit, 300 rods west ; on the fourth circuit, 400 rods, and so on, continually. 
 After 71% circuits, the point of intersection would be one degree west of its place at the 
 commencement of the route. At this rate it would be easy to determine how many com- 
 plete circuits the carriage must perform before this continual falling back of the inter- 
 secting point would have retreated over every degree of the orbit, until it reached again 
 the point from whence it first departed. The application of this illustration will be mani- 
 fest when we consider, further, 
 that this interesting phenomenon 
 may be explained in another 
 way by the a<ijoining diagram. 
 Let the point A represent the 
 vernal equinox, reached, for in- 
 stance, at 12 o'clock on the 20th 
 of March. The next year the 
 Sun will b'e in the equinoctial 22 
 minutes 33 seconds earlier, at 
 which time the Earth will be 
 50%" on the ecliptic, back of the 
 point at which the Sun was in 
 the equinoctial the year before. 
 The next year the same will oc- 
 cur again ; and thus the equi- 
 noctial point will recede west- 
 ward little by little, as shown by 
 the- small lines from A to B, and 
 from C to I). It is in reference 
 to the stars going forward, or 
 seeming to precede the equi- 
 noxes, that the phenomenon is 
 called the Precession of the Equi- 
 noxes. But in reference to the 
 motion of the equinoxes them- 
 telves, it is rather a recession. 
 
 577. The Sun revolves from one equinox to the same equinox 
 again, in 365d. 5h. 48' 47" 81. This constitutes the natural, or 
 tropical year, because, in this period, one revolution of the sea- 
 sons is exactly completed. But it is, meanwhile, to be borne in 
 mind, that the equinox itself, during this period, has not kept 
 its position among the stars, but has deserted its place, and 
 fallen lack a little way to meet the Sun ; whereby the Sun has 
 arrived at the equinox before he has arrived at the same position 
 among the stars from which he departed the year before ; and, 
 consequently, must perform as much more than barely a tropical 
 revolution, to reach that point again. 
 
 To pass over this interval, which completes the Sun's sidereal 
 revolution, takes (20' 22".94) about 22 minutes and 23 seconds 
 longer. By adding 22 minutes and 23 seconds to the time of a 
 tropical revolution, we obtain 365d. 6h. 9m. lOfs. for the length 
 of a sidereal revolution ; or the time in which the Sun revolves 
 from one fixed star to the same star again. 
 
 Though we speak of the revolution of the Fun, we mean simply his apparent revolution 
 eastward around the heavens, caused wholly by the actual revolution of the Earth in her 
 
 actually revolve? Why, then, speak of his revolution? 577. What is the length of a 
 tropical year ? How different from a sidereal year ? Difference of time T Length of a 
 aidereal year ? 
 
PRECESSION OF THE EQUINOXES. 
 
 273 
 
 orbit, aa a distant object would appear to sweep around the horizon if we were walking 
 or sailing around it. This may be illustrated by the cut, page 288- where the passage 
 of the Earth from A to B would cause the Sun to appear to move from C to D j and S3 on 
 around the whole circle of the Zodiac. 
 
 578. As the Sun describes the whole ecliptic, or 360, in a 
 tropical year, he moves over 59' 8" of a degree every day, at a 
 mean rate, which is equal to 50^" of a degree in 20 minutes and 
 23 seconds of time ; consequently he will arrive at the same 
 equinox or solstice when he is 50" of a degree short of the. same 
 star or fixed point in the heavens, from which he set out the 
 year before. So that, with respect to the fixed stars, the Suii 
 and equinoctial points fall back, as it were, 1 in 7 If years. 
 This will make the stars appear to have gone forward 1, with 
 respect to the signs in the ecliptic, in that time ; for it must be 
 observed, that the same signs always keep in the same points of the 
 ecliptic, without regard to the place of the constellations. Hence it 
 becomes necessary to have new plates engraved for celestial 
 globes and maps, at least once in 50 years, in order to exhibit 
 truly the altered position of the stars. At the present rate of 
 motion, the recession of the equinoxes, as it should be called, or 
 the precession of the stars, amounts to 30, or one whole sign, in 
 2140 years. 
 
 PRECESSION OP THE STABS. 
 
 To explain this by a figure : Suppose the Sun to have been in conjunction with a fixea 
 star at S, in the first degree of Taurus (the second sign of the ecliptic), 840 years before 
 the birth of our Saviour, or about the seventeenth year of Alexander the Great; then 
 having made 2140 revolutions through the ecliptic, he would be found again at the end of 
 so many sidereal years at S ; but at the end of so many Julian years, he would be found 
 at J, and at the end of so many tropical years, which would bring it down to the begin- 
 ning of the present century, he would be found at T, in the first degree of Aries, which 
 
 578. Daily progress of the Sun ? What is the amount of the annual recession of the 
 equinoxes ? What effect will this have upon the apparent positions of the stars ? Hence 
 what becomes necessary? How long does it require for the equinoxes to recede a wiolo 
 sign ? Do you understand the diagram, and the reference to the sidereal, Julian, aud 
 Tropical years? Explain the difference in the=e three kinds of yeara. 
 
274 ASTRONOMY. 
 
 has receded from S to T in that time by the precession of the equinoctial points Aries anU 
 Libra. The arc S T would be equal to the amount of the precession (for precession we 
 must still call it) of the equinox in 2140 years, at the rate of 50".23572 of a degree, or 20 
 minutes and 23 seconds of time annually, as above stated. 
 
 519. From the constant retrogradation of the equinoctial 
 points, and with them of all the signs of the ecliptic, it follows 
 that the longitude of the stars must continually increase. The same 
 cause affects also their right ascension and declination. Hence, 
 those stars which, in the infancy of astronomy, were in the sign 
 Aries, we now find in Taurus ; and those which were in Taurus, 
 we now find in Gemini, and so on. Hence likewise it is, that 
 the star which rose or set at any particular time of the year, ID. 
 the time of Hesiod, Eudoxus, Yirgil, Pliny, and others, by 110 
 means answers at this time to their descriptions. 
 
 Hesiod, in his Opera et Dies, lib. ii. verse 185, says : 
 
 " When from the solstice sixty wintry days 
 Their turns have finished, mark, with glitt'ring rays, 
 From Ocean's sacred flood, Arcturus rise, 
 Then first to gild the dusky evening skies." 
 
 But Arcturus now rises acronically in latitude 37 45' N. the latitude of Hesiod, ana 
 nearly that of Richmond, in Virginia, about 100 days after the winter solstice. Suppos- 
 ing Hesiod to be correct, there is a difference of 40 days arising from the precession of 
 the equinoxes since the days of Hesiod. Now, as there is no record extan,t of the exact 
 period of the world when this poet flourished, let us see to what result astronomy will 
 lead us. 
 
 As the Sun moves through about 39 of the ecliptic in 40 days, the winter solstice, in 
 the time of Hesiod, was in the 9th degree of Aquarius. Now, estimating the precession 
 of the equinoxes at 50%" in a year, we shall have 503^* : 1 year : : 39 : 2814 years since the 
 time of Hesiod : if we subtract from this our present era, 1855, it will give 958 years before 
 Christ. Lempriere, in his Classical Dictionary, says Hesiod lived 907 years before Christ. 
 See a similar calculation for the time of Thales, page 39. 
 
 580. The retrograde movement of the equinoxes, and the 
 annual extent of it, were determined by comparing the longitude 
 of the same stars, at different intervals of time. The most care- 
 ful and unwearied attention was requisite in order to determine 
 the cause and extent of this motion a motion so very slow as 
 scarcely to be perceived in an age, and occupying not less than 
 25,000 years in a single revolution. It has not yet completed 
 one quarter of its first circuit in the heavens since the creation 
 of Mars. 
 
 581. This observation has not only determined the absolute 
 motion of the equinoctial points, but measured its limit ; it has 
 also shown that this motion, like the causes which produce it, is 
 not uniform in itself ; but that it is constantly accelerated by a 
 
 579. What effect has the recession of the equinoxes upon the longitude of the stars, and 
 their right ascension and declination ? Hence what results ? What interesting calcu- 
 lation in reference to Hesiod ? 580. How were this recession and its extent determined ? 
 What necessary? Time of complete revolution? Amount since creation? 681. Ie 
 this retrogression uniform? Amount of acceleration ? What illustration given ? 
 
PRECESSION OF THE EQUINOXES. 275 
 
 islow arithmetical increase of I" of a degree in 4100 years. A 
 quantity which, though totally inappreciable for short periods of 
 time, becomes sensible after a lapse of ages. 
 
 For example : The retrogradation of the equinoctial points is now greater by nearlj Jg' 
 xhan it was in the time of Hipparchus, the first who observed this motion ; consequently, 
 the mean tropical year is shorter now by about 12 seconds than it was then. For, since 
 the retrogradation of the equinoxes is now every year greater than it was then, the Sun 
 has, each year, a space of nearly Jg" less to pass through in the ecliptic, in order to reach 
 the plane of the equator. Now the Sun is 12 seconds of time in passing over %' of space. 
 
 582. At present, the equinoctial points move backwards, or 
 from east to west along the path of toe ecliptic at the rate of 1 
 in 7 If years, or one whole sign in 2140 years. Continuing at 
 this rate, they will fall back through the whole of the 12 signs 
 of the ecliptic in 25,680 years, and thus return to the same posi- 
 tion among the stars, as in the beginning. 
 
 But in determining the period of a complete revolution of the 
 equinoctial points, it must be borne in mind that the motion itself 
 is continually increasing; so that the last quarter of the revolu- 
 tion is accomplished several hundred years sooner than the first 
 quarter. Making due allowance for this accelerated progress, 
 the revolution of the equinoxes is completed in 25,000 years ; 
 or, more exactly, in 24,992 years. 
 
 Were the motion of the equinoctial points uniform ; that is, did they pass through 
 equal portions of the ecliptic in equal times, they would accomplish their first quarter, or 
 pass through the first three signs of the ecliptic, in 6250 years. But they are 6575 years 
 in passing through the first quarter ; about 218 years less in passing through the second 
 quarter; 218 less in passing through the third, and so on. 
 
 583. The immediate consequence of the precession of the equi- 
 noxes, as we have already observed, is a continually progressive 
 increase of longitude in all the heavenly bodies. For the vernal 
 equinox being the initial point of longitude, as well as o* right 
 ascension, a retreat of this point on the ecliptic tells upon the 
 longitude of all alike, whether at rest or in motion, and pro- 
 duces, so far as its amount extends, the appearance of a motion 
 in longitude common to them all, as if the whole heavens had a 
 slow rotation around the poles of the ecliptic in the long period 
 above mentioned, similar to what they have in every twenty-four 
 hours around the poles of the equinoctial. As the Sun loses one 
 day in the year on the stars, by his direct motion in longitude ; 
 so the equinox gains one day on them in 25,000 years, by its 
 retrograde motion. 
 
 582. Present rate of motion ? Exact period at Wls rate ? Period making allowance 
 for acceleration? Time of passing over the first quarter of the ecliptic? The second? 
 Third? 533. What immediate consequences of the precession of the equinoxes? 
 Why does it affe- the longitude of the stars ? What resemblance between the motion of 
 the celestial spher and that of the Earth ? Between the Sun and equinoxes? 
 
 12* 
 
276 
 
 ASTRONOMY. 
 
 584. The cause of this motion was unknown, until Aewton 
 proved that it was a necessary consequence of the rotation of 
 the Earth, combined with its elliptical figure, and the unequal 
 attraction of the Sun and Moon on its polar and equatorial 
 regions. There being more matter about the Earth's equator 
 than at the poles, the former is more strongly attracted than 
 the latter, which causes a slight gyratory or wabbling motion of 
 the poles of the Earth around those of the ecliptic, like the pin 
 of a top about its center of motion, when it spins a little 
 obliquely to the base. 
 
 585. The precession of the equinoxes, thus explained, consists 
 in a real motion of the pole of the heavens among the stars, in a 
 small circle around the pole of the ecliptic as a center, keeping 
 constantly at its present distance of nearly 23 from it, in a 
 direction from east to west, and with a progress so very slow, 
 as to require 25,000 years to complete the circle. During this 
 revolution, it is evident that the pole will point successively to 
 every part of the small circle in the heavens which it thus 
 describes. Now this cannot happen without producing corre- 
 sponding changes in the apparent diurnal motion of the sphere, 
 and in the aspect which the heavens must present at remote 
 periods of time. 
 
 NUTATION OF THB EARTH'S AXIS. 
 B 
 
 Let the line A A in the figure re- 
 present the plane of the ecliptic; 
 B B, tne poles of the ecliptic ; C C, 
 the poles of the Earth ; and D D, the 
 equin -dial. & E is the obliquity of 
 the ecliptic. The star C, at the top, 
 represents the pole star, and the 
 curve Mne passing to the right from 
 it, may represent the circular orbit 
 of the north pole of the hearens 
 around the north pole of the ecliptic. 
 
 586. The effect of such 
 a motion on the aspect of 
 the heavens, is seen in the 
 apparent approach of some 
 stars and constellations to 
 the celestial pole, and the 
 recession of others. The 
 bright star of the Lesser 
 Bear, which we call the pole star, has not always been, nor will 
 always continue to be, our polar star. At the time of the con- 
 
 584. What said of the cause of this recession? 585. what, then, does it consist? 
 What said of the pole of the ecliptic, and the aspects of t. neavens during this revolu- 
 tion? 685. How is the effect of this motion manifos <d? How with the Pole star if 
 
PRECESSION OF THE EQUINOXES. 277 
 
 struction of the earliest catalogue, this star was 12 from the 
 pole ; it is now only 1 34' from it, and it will approach to 
 within half a degree of it ; after which it will again recede, and 
 slowly give place to others, which will succeed it in its proximity 
 to the pole. 
 
 The pole, as above considered, is to be understood, merely, as the vanishing point of 
 the Earth's axis; or that point in the concave sphere which is always opposite the 
 terrestial pole, and which consequently must move as that moves. 
 
 587. The precession of the stars in respect to the equinoxes, 
 is less apparent the greater their distance from the ecliptic ; for 
 whereas a star in the zodiac will appear to sweep the whole 
 circumference of the heavens in an equinoctial year, a star situ- 
 ated within the polar circle will describe only a very small circle 
 in that period, and by so much the less, as it approaches the 
 pole. The north pole of the Earth being elevated 23 27|' 
 towards the tropic of Cancer, the circumpolar stars will be suc- 
 cessively at the least distance from it, when their longitude i& 
 3 signs or 90. 
 
 588. The position of the north polar star in 1855, was in the 
 17 of Taurus; when it arrives at the first degree of Cancer, 
 which it will do in about 250 years, it will be at its nearest 
 possible approach to the pole namely, 29' 55". About 2900 
 years before the commencement of the Christian era, Alpha Dra- 
 conis, the third star of the Dragon's tail, was in the first degree 
 of Cancer, and only 10' from the pole ; consequently it was then 
 the pole star. After the lapse of 11,600 years the star Lyra, 
 the brightest in the northern hemisphere, will occupy the position 
 of a pole star, being then about 5 degrees from the pole ; 
 whereas now its north polar distance is upward of 51. 
 
 The mean average precession from the creation (4004 B. C.) to the year 1800, is 
 49'.51455; consequently the equinoctial points have receded since the creation, 2s. 14* 8' 
 27". The longitude of the star Seta Arietiz, was in 1820, 81 27' 28" : Meton, a famous 
 mathematician of Athens, who flourished 480 years before Christ, says, this star, in his 
 time, was in the vernal equinox. If he is correct, then 31 27' 2S\ divided by 2250 years, 
 the elapsed time, will give 50 %" for the precession. Something, however, must be 
 allowed for the imperfection of the instruments used at that day, and even until the six- 
 teenth century. 
 
 589. Since all the stars complete half a revolution about the 
 axis of the ecliptic in about 12,500 years, if the North Star be 
 at its nearest approach to the pole 250 years hence, it will, 
 
 What, then, is the real pole of the heavens ? 587. Where is the precession of the stara 
 most apparent? Where least? When are the circumpolar stars nearest the tropic of 
 Cancer, and why? 588. Where was the pole star in 1855? When will it be neareat 
 the true pole? How near then? What said of Alpha DraconU* Of Lyra t Mean 
 average recession for 5800 years? Amount? Longitude of Bfta A rieUs in 1820? Be- 
 fore Christ 430 years, where ? Average of precession for these 2250 years ? 589. What 
 further result of the revolution of the pole of the heavens ? What effect ? "ft here, then, 
 
279 
 
 ASTRONOMY. 
 
 12,500 years afterwards, be at its greatest possible distance 
 from it, or about 47 above it : That is, the star itself will 
 remain immovable in its present position, but the pole of the 
 Earth will then point as much below the pole of -the ecliptic, as 
 now it points above. This will have the effect, apparently, of 
 elevating the present polar star to twice its present altitude, or 
 47. Wherefore, at the expiration of half the equinoctial year, 
 that point of the heavens which is now 1 18' north of the zenith 
 of Hartford, will be the place of the north pole, and all those 
 places which are situated 1 18' north of HartfoH, will then 
 have the present pole of the heavens in their zenith. 
 
 OBLIQUITY OF THE ECLIPTIC. 
 
 590. The inclination of the Earth's axis to the plane of the 
 ecliptic causes the equinoctial to depart 23 28' from the eclip- 
 tic. This angle made by the equinoctial and the ecliptic is 
 called the Obliquity of the Ecliptic. 
 
 OBLIQUITY OP THE ECLIPTIC. 
 
 A 
 
 Let the line A A represent 
 the axis of the Earth, and fi B 
 the poles or axis of the eclip- 
 tic. Now if the line A A in- 
 clines toward the plane of the 
 ecliptic, or, in other words, 
 departs from the line B, to 
 the amount of 23 28', it is 
 obvious that the plane of the 
 equator, or equinoctial, will PLANE Of 
 depart from the ecliptic to the " 
 same amount. This depar- 
 ture, shown by the angles 
 C C, constitute the obliquity 
 of the ecliptic. 
 
 591. Hitherto, we 
 have considered these 
 great primary circles 
 in the heavens, as never varying their position in space, nor with 
 respect to each other. But it is a remarkable and well-ascer- 
 tained fact, that both are in a state of constant change. We 
 have seen that the plane of the Earth's equator is constantly 
 drawn out of place by the unequal attraction of the Sun and 
 Moon acting in different directions upon the unequal masses of 
 matter at the equator and the poles ; whereby the intersection 
 of the equator with the ecliptic is constantly retrograding thus 
 producing the precession of the equinoxes. 
 
 590. What is th-OWquityof 
 the same? \Vhat variation of the equinoctial? 
 
PRECESSION OF 'THE EQUINOXES. 279 
 
 592. The displacement of the ecliptic, on the contrary, is pro- 
 duced chiefly by the action of the planets, particularly of Jupi- 
 ter and Yenus, on the Earth ; by virtue of which the plane of 
 the Earth's orbit is drawn nearer to those of these two planets, 
 and consequently, nearer to the plane of the equinoctial. The 
 tendency of this attraction of the planets, therefore, is to dimi* 
 nish the angle, which the plane of the equator makes with that 
 of the ecliptic, bringing the two planes nearer together ; and if 
 the Earth had no motion of rotation, it would, in time, cause 
 the two planes to coincide. But in consequence of the rotary 
 motion of the Earth, the inclination of these planes to each other 
 remains very nearly the same ; its annual diminution being scarcely 
 more than three-fourths of one second of a degree. 
 
 The obliquity of the ecliptic, at the commencement of the present century was, accord- 
 ing to Batty, 23 27' 56 3", subject to a yearly diminution of 0".4755. According to Bes- 
 6el, it was 23 27' 54" .32, with an annual diminution of 0".46. At this date (1855), it is only 
 about 23* 27' 29". Consequently, the angle is diminished about 27" in 55 years. This 
 diminution, however, is subject to a slight semi-annual variation, from the same causes 
 which produce the displacement of the plane of the ecliptic, in precession. 
 
 593. The attraction of the Sun and Moon, also, unites with 
 that of the planets, at certain seasons, to augment the diminu- 
 tion of the obliquity, and at other times, to lessen it. On this 
 account the obliquity itself is subject to a periodical variation ; 
 for the attractive power of the Moon, which tends to produce a 
 change in the obliquity of the ecliptic, is variable, while the diur- 
 nal motion of the Earth, which tends to prevent the change from 
 taking place, is constant. Hence the Earth, which is so nicely 
 poised on her center, bows a little to the influence of the Moon, 
 and rises again, alternately, like the gentle oscillations of a 
 balance. This curious phenomenon is called Nutation (589). 
 
 In consequence of the yearly diminution of the obliquity of the ecliptic, the tropics are 
 slowly and steadily approaching the equinoctial, at the rate of little more than three- 
 fourths of a second every year; so that the Sun does not now come so far north of tl:e 
 equator in summer, nor decline so far south in winter, by nearly a degree, as it must 
 have done at the Creation. 
 
 594. The most obvious effect of this diminution of the obli- 
 quity of the ecliptic, is to equalize the length of our days and 
 nights ; but it has an effect also to change the position of the 
 stars near the tropics. Those which were formerly situated 
 north of the ecliptic, near the summer solstice, are now found to 
 be still farther north, and farther from the plane of the ecliptic. 
 On the contrary, those which, according to the testimony of the 
 
 592. What displacement of the ecliptic, and by what caused ? Effect of these causes ? 
 Amount of change annually? Obliquity of the ecliptic in 1800? In 1855? 593. Diminution 
 In 55 years? What is Nutation? Its cause? What effect from this annual diminu- 
 tion of obliquity? 594. What other effect? Will this diminution continue? What 
 
280 
 
 ASTRONOMY. 
 
 ancient astronomers, were situated south of the ecliptic, near the 
 summer solstice, have approached this plane, insomuch that some 
 are now either situated within it, or just on the north side of it. 
 Similar changes have taken place with respect to those stars 
 situated near the winter solstice. All the stars, indeed, partici- 
 pated more or less in this motion, but less, in proportion to their 
 proximity to the equinoctial. 
 
 It is important, however, to observe, that this diminution will not always continue. A 
 time will arrive when this motion, growing less and less, will at length entirely cease, 
 and the obliquity will, apparently, remain constant for a time ; after which it will gra- 
 dually increase again, and continue to diverge by the same yearly increment as it before 
 had diminished. This alternate decrease and increase will constitute an endless oscilla- 
 tion, comprehended between certain fixed limits. Theory has not yet enabled us to 
 determine precisely what these limits are, but it may be demonstrated from the constitu- 
 tion of our globe, that such limits exist, and that they are very restricted, probably not 
 exceeding 2 42'. If we consider the effect of this ever-varying attribute in the system 
 of the universe, it may be affirmed that the plane of the ecliptic never has coincided 
 with the plant? of the equator, and never will coincide with it. Such a coincidence, 
 could it happen, would produce upon the Earth perpetual spring. 
 
 595. The method used by astronomers to determine the 
 obliquity of the ecliptic is, to take half the difference of the 
 greatest and least meridian altitudes of the Sun. 
 
 The following table exhibits the mean obliquity of the ecliptic for every ten years 
 during the present century. 
 
 1800 
 1810 
 1820 
 1830 
 1840 
 1850 
 
 23" 
 23 
 23 
 23 
 23 
 23 
 
 27' 
 27 
 27 
 27 
 27 
 27 
 
 54". 78 
 50 .21 
 45 .64 
 41 .07 
 36 .50 
 31 .93 
 
 1860 
 1870 
 1880 
 1890 
 1900 
 1910 
 
 23" 
 28 
 23 
 23 
 23 
 23 
 
 27' 
 27 
 27 
 27 
 27 
 27 
 
 27' .36 
 22 .79 
 18 .22 
 13 .65 
 09 .08 
 04 .52 
 
 CHAPTER XIII. 
 
 PHILOSOPHY OF THE TIDES. 
 
 596. TIDES are the alternate rising and falling of the waters 
 of the ocean, at regular intervals. Flood tide is when~the waters 
 are rising ; and ebb tide, when they are falling. The highest 
 and lowest points to which they go are called, respectively, high 
 and low tides. The tides ebb and flow twice every twenty-four 
 hours i. e., we have two flood and two ebb tides in that time. 
 
 jycle of oscillation? Its probable limits? What conclusion from this oscillation of the 
 ecliptic? 595. By what meihod do astronomers determine the obliquity of the ecliptic? 
 590. Wbit are tides? Flood and ebb tides? High and low? Uow often do 'hey c-bo 
 and flow ? 
 
PHILOSOPHY OF THE TIDES. 
 
 281 
 
 597. The tides are not uniform, either as to time or amount. 
 They occur about 50 minutes later every day (as we shall 
 explain hereafter), and sometimes rise much higher and sink 
 much lower than the average. These extraordinary high and 
 low tides are called, respectively, spring and map tides. 
 
 598. The cause of the tides is the attraction of the Sun and 
 Moon upon the water of the ocean. But for this foreign influ- 
 ence, as we may call it, the waters having found their proper 
 level, would cease to heave and swell, as they now Nrt TinK 
 do, from ocean to ocean, and would remain calm 
 
 and undisturbed, save by their own inhabitants and 
 the winds of heaven, from age to age. 
 
 In this figure, the Earth is represented as surrounded by water, in a 
 state of rest or equilibrium, as it would be were it not acted upon by 
 the Sun and Moon. 
 
 599. To most minds, it would seem that the natural effect ot 
 the Moon's attraction would be to produce a single tide-wave 
 on the side of the Earth toward the Moon. It is easy, there- 
 fore, for students to conceive how the Moon can produce one 
 flood and one ebb tide in twenty four hours. 
 
 In this cut, the Moon is shown at a distance above the Earth, and ONB TIDE-WAVK. 
 attracting the waters of the ocean, so as to produce a high tide at A. 
 But as the moon makes her apparent westward revolution around the 
 Earth but once a day, the simple rising of a flood tide on the side of the 
 Earth toward the moon, would give give us but one flood and one ebb 
 tide in twenty-four hours ; whereas it is known that we have two of 
 each. 
 
 " The tides," says Dr. Herschel, " are a subject on which many per- 
 sons find a strange difficulty of conception. That the Moon by her 
 attraction, should heap up the waters of the ocean under her, seems to 
 many persons very natural. That the same cause should, at the same 
 time, heap them up on the opposite side of the Earth (viz., at B in the 
 figure), seems to many palpably absurd. Yet nothing is more true." 
 
 600. Instead of a single tide-wave upon the waters Two TIDE- WAVER. 
 of the globe, directly under the Moon, it is found 
 
 that on the side of the Earth directly opposite, 
 there is another hign tide ; and that half-way 
 between these two high tides are two low tides. 
 These four tides, Viz., two high and two low, 
 traverse the ocean from east to west every day, 
 which accounts for both a flood and an ebb tide 
 every twelve hours. 
 
 597 Are the tides uniform? What variation of time? As to amount? What are 
 these extraordinary high and low tides called? 598. The cause of tides? How but 
 for this influence ? 599. What most obvious effect of the Moon's attraction ? Substance 
 of note? Remark of Dr. Herschel? 600. How many tide-waves are there on the 
 globe, and how situated ? 
 
 
 
ASTRONOMY. 
 
 In this cut, we have a representation of the tide-waves as they actually exist, exocot 
 that their height, as compared with the magnitude of the Earth, is vastly too great. 
 It is designedly exaggerated, the better to illustrate the principle under consideration. 
 While the Moon at A attracts the waters of the ocean, and produces a high tide at B, 
 we see another high tide at C on the opposite side of the globe. At the same time it is 
 low tide at D and . 
 
 601. The principal cause of the tide-wave on the side of the 
 Earth opposite the Moon is the difference, of the Moon's attrac- 
 tion on different sides of the Earth. 
 
 If the student well understands the subject of gravitation, he will easily perceive 
 how a difference of attraction, as above described, would tend to produce an elongation 
 of the huge drop of water called the Earth. The diameter of the Earth amounts to about 
 J_th of the Moon's distance ; so that, by the rule (558), the difference in her attraction 
 on the side of the Earth toward her, and the opposite side, would be about y^th. The 
 attraction being stronger at B (in the last cut) than at the Earth's center, and stronger 
 at her center than at C, would tend to separate these three portions of the globe, giving 
 the waters an elongated form, aud producing two opposite tide-waves, as shown in 
 the cut. 
 
 602. A secondary cause of the tide-wave on the side of the 
 Earth opposite the Moon, is the revolution of the Earth around 
 the common center of gravity between the Earth and Moon, 
 thereby generating an increased centrifugal force on that side 
 of the Earth. 
 
 The center of gravity between the Earth and Moon is the point where they would 
 exactly balance each other, if connected by" a rod, and poised upon a fulcrum. 
 
 CKNTEB OF GRAVITY BETWEEN THE EARTH AND MOON. 
 
 Moon. 
 
 o 
 
 This point which, according to Ferguson, is about 6000 miles from the Earth's center, 
 la represented at A in the above, and also in the next cut 
 
 SECONDARY CAUSE OF HIGH TIDE OPPOSITE THE MOON. 
 
 The point A represents the center of gravity between the Earth and Moon ; and as it 
 lj tnis point which traces the regular curve of the Earth's orbit, it is represented in the 
 arc of that orbit, while the Earth's center is 6000 miles one side of it. Now, the law of 
 gravitation requires that while both the Moon and Earth revolve around the Sun, they 
 ehould also revolve around the common center of gravity between them, or around tho 
 point A. This would give the Earth a third revolution, in addition to that around thf 
 
 601. State the principal cause of the wave opposite the Moon? Demonstrate by dia- 
 gram. 602. What other cause operates with the one just stated to pro<l ice the tide- 
 wave opposite the Moon ? What is the center of gravity between the Earth and the 
 Moon ? Where is it situated ? Illustrate the operation of this secondary cause. 
 
PHILOSOPHY OF T'lE TIDES. 283 
 
 Sun and on her axis. The small circles show her path around the center of gravity, and 
 the arrows her direction. 
 
 This motion of the Earth would slightly increase the centrifugal tendency ai B, and 
 thus help to raise the tide-wave opposite the Moon. But as this motion is slow, corre- 
 sponding with the revolution of the Moon around the Earth, the centrifugal force could 
 not be greatly augmented by such a cause. 
 
 603. As the Moon, which is the principal cause of the tides, 
 is revolving eastward, and comes to the meridian later and later 
 every night, so the tides are about 50 minutes later each success- 
 ive day. This makes the interval between two successive high 
 tides 12 hours and 25 minutes Besides 
 
 this daily lagging with the Moon, the 
 highest point of the tide-wave is found 
 to be about 46 behind, or east of the 
 Moon, so that high tide does not , 
 occur till about three hours after the 
 Moon has crossed the meridian. The 
 waters do not at once yield to the im- 
 pulse of the Moon's attraction, but 
 continue to rise after she has passed 
 over. 
 
 In the cut, the Moon is on the meridian, but the highest point of the wave is at A, or 
 45 east of the meridian ; and the corresponding wave on the opposite side at B is equally 
 behind. 
 
 604. The time and character of the tides are also affected by 
 winds, and by the situation of different places. Strong winds 
 may either retard or hasten the tides, or may increase or diminish 
 their height ; and if a place is situated on a large bay, with but 
 a narrow opening into the sea, the tide will be longer in rising, 
 as the bay has to fill up through a narrow gate. Hence it is 
 not usually high tide at New York till eight or nine hours after 
 the Moon has passed the meridian. 
 
 605. As both the Sun and Moon are concerned in the produc- 
 tion of tides, and yet are constantly changing their positions 
 with respect to the earth and to each other, it follows that they 
 sometimes act against each other, and measurably neutralize each 
 other's influence ; while at other times they combine their forces, 
 and mutually assist each other. In the latter case, an unusually 
 high tide occurs, called the Spring Tide. This happens both at 
 new and full Moon. 
 
 608. What daily lagging of the tides ? Interval between two successive high tides ? 
 What other lagging? Cause of this last? 604. What modification of the time and 
 character of the tides ? 605. Do the Sun and Moon always act together in attracting 
 the waters? Why not? How affect each other's influence ? Effect on the tides ? What 
 t.re Spring Tides? When do they occur? Illustrate by diagram the cause of spring 
 tides, when the Sun and Moon are in conjunction. 
 
284 
 
 ASTRONOMY. 
 
 CAUSK OF SPBINO TIDB3. 
 
 Here the Sun and Moon, being in conjunction, unite their forces to produce an extra, 
 ordinary tide. The same effect follows when they are in opposition ; so that we have 
 two spring tides every month namely, at new and full Moon. 
 
 If the tide-waves at A and B are one-third higher at the Moon's quadrature than usual, 
 those of C and D will be one-third lower than usual. 
 
 606. When the Moon is in quadrature, and her influence is 
 partly neutralized by the Sun, which now acts against her, the 
 result is a very low tide, called Neap Tide. 
 
 SPRING AND NEAP TIDES. 
 
 The whole philosophy of spring and 
 neap tides may be illustrated by the an- 
 nexed diagram. 
 
 On the right side of the cut, the Sun 
 and Moon are in conjunction, and unite 
 to produce a spring tide. 
 
 'At the first quarter, their attraction 
 acts at right angles, and the Sun, instead 
 of contributing to the lunar tide-waves, 
 detracts from it to the amount of his 
 own attractive force. The tendency to 
 form a tide of his own, as represented in 
 the figure, reduces the Moon's wave to 
 the amount of one-third. 
 
 At the full Moon, she is in opposition 
 to the Sun, and their joint attraction 
 acting again in the same line, tends to 
 elongate the fluid portion of the Earth, 
 and a second spring tide is produced. 
 
 Finally, at the third quarter, the Suu 
 and Mtoon act against each other again, 
 and the second neap tide is the result. 
 Thus we have two spring and two neap 
 tides during every lunation the former 
 at the Moon's cyzygies, and the latter at her quadratures. 
 
 607. Although the Sun attracts the Earth much more power 
 fully, as a whole, than the Moon does, still the Moon contributes 
 more than the Sim to the production of tides. Their relative 
 influence is as one to three. The nearness of the Moon makes 
 
 606. What are Neap Tides f Their cause ? Illustrate entire philosophy by diagram. 
 607. Comparative influence of Sun and Moon in the production of tides ? Why Moon 1 - 
 Infiucnce the greatest? Substance of note ? Demonstration? 
 
PHILOSOPHY OF THE TIDES. 
 
 285 
 
 the difference, of her attraction on different sides of the Earth 
 much greater than the difference of the Sun's attraction on dif- 
 ferent sides. 
 
 It must not be forgotten that the tides are the result not so much of the attraction of 
 the Sun and Moon, as a whole, as of the difference in their attraction on different sides 
 of the Earth, caused by a difference in the distance* of the several parts. The attrac- 
 tion being inversely as the square of the distance (558), the influence of the Sun and 
 Moon, respectively, must be in the ratio of the Earth's diameter to their distances. Now 
 
 the difference in the distance of two sides of the Earth from the Moon is -o^th of the 
 Moon's distance ; as 240,000-1-8,000=80 ; while the difference, as compared with the dis* 
 tance of the Sun, is only TT tYJ th ' as 95,000,000+8,000=11,875. 
 
 TIDES AFFECTED BY DECLINA- 
 TION. 
 
 608. The tides are subject to another periodic variation, 
 caused by the declination of the Sun and 
 Moon north and south of the equator. 
 As the tendency of the tide-wave is to 
 rise directly under the Sun and Moon, 
 when they are in the south, as in winter, 
 or in the north, as in summer, every 
 alternate tide is higher than the interme- 
 diate one. 
 
 At the time of the equinoxes, the Sun being over the 
 equator, and the Moon within 5& of it, the crest of the 
 great tide-wave will be on the equator ; but as the Sun 
 and Moon decline south to A, one tide-wave forms in the 
 south, as at B, and the opposite one in the north, as at 
 C. If the declination was north, as shown at D, the order of the tides would be reversed. 
 The following diagram, if carefully studied, will more fully illustrate the subject of tn 
 alternate high and low tides, in high latitudes, in winter and summer : 
 
 ALTERNATE HIGH AND LOW TIDES. 
 
 let the line A A represent the plane of the ecliptic, and B B the equinoctial. On the 
 21st of June, the day tide-wave is north, and the evening wave south, so that the tide 
 following about three hours after the Sun and Moon, will be higher than the intermediate 
 one at 3 o'clock in the morning. 
 
 On the 23d of December, the Sun and Moon being over the southern tropic, the 
 highest wave in the southern hemisphere will be about 8 o'clock P. M , and the lowest 
 about 3 o'clock A.M. ; while at the north, this order will be reversed. It is on this 
 account that in high latitudes every alternate tide is higher than the intermediate ones ; 
 the evening tides in summer exceeding the morning tides, and the morning tides in win- 
 ter exceeding those of evening. 
 
 609. All spring and neap tides are not alike as to their eleva 
 tion and depression. As the distances of the Sun and Moon arc 
 
 608. What other periodic variations mentioned? Explain cause, and illustrate* 
 fioy. Are all spring and neap ti']f-s alike? By what are they modified? Illustrate ly 
 
 di.-igram. 
 
5*86 
 
 ASTRONOMY. 
 
 varied, so are the tides varied, especially by the variations of 
 the Moon. 
 
 VARIATIONS IN THE SPRING TIDES. 
 
 At A, the Earth is in aphelion, and the Moon in apogee. As both the Sun and Moon 
 are at their greatest distances, the Earth is least affected by their attraction, arid the 
 spring tides are proportionately low. 
 
 A j B, the Earth is in perihelion, and the Moon in perigee; so that both the Sun and 
 Moon exert their greatest influence upon our globe, and the spring tides are highest, aa 
 ehewn in the figure. In both cases, the Sun and Moon are in conjunction, but the varia- 
 tion in the distances of the Sun and Moon causes variations in the spring tides. 
 
 610. In the open ocean, especially the Pacific, the tide rises 
 and falls but a few feet ; but when pressed into narrow bays 
 or channels, it rises much higher than under ordinary cir- 
 cumstances. 
 
 The average elevation of the tide at several points on our coast is as follows : 
 
 Cumberland, head of the Bay of Fundy 71 feel. 
 
 * Boston 11^ " 
 
 New Haven 8 " 
 
 New York 5 " 
 
 Charleston, S. C 6 " 
 
 611. As the great tide-waves proceed from east to west, they 
 are arrested by the continents, so that the waters are per- 
 manently higher on their east than on their west sides. The 
 Gulf of Mexico is 20 feet higher than the Pacific Ocean, on the 
 other side of the Isthmus ; and the Red Sea is 30 feet higher 
 than the Mediterranean. Inland seas and lakes have no per- 
 ceptible tides, because they are too small, compared with the 
 whole surface of the globe, to be sensibly affected by the attrac- 
 tion of the Sun and Moon. 
 
 ATMOSPHERICAL TIDES. 
 
 612. Air being lighter than water, and the surface of the 
 atmosphere being nearer to the Moon than the surface o' the 
 sea, it cannot be doubted but that the Moon raises much higner 
 
 610. Height of tides in open seas ? How in narrow bays and channels ? Height at dif- 
 ferent points on our coast ? 611. Direction of tide-waves? What result? Instances 
 cited? Have inland seas and lakes any tides? Why not ? Remarks respecting p)u- 
 iosophy of tides ? 612 Atmospheric tides ? 
 
TtlE SEASONS. 287 
 
 tides in the atmosphere than in the sea. According to Sir 
 John Herschel these tides are, by very delicate observations, 
 rendered not only sensible, but measurable. 
 
 Upon the supposition that there is water on the surface of the Moon of the same 
 specific gravity as our own, we might easily determine the height to which the Earth 
 would raise a lunar tide, by the known principle, that the attraction of one of these 
 bodies on the other's surface is directly as its quantity of matter, and inversely as its 
 diameter. By making the calculation, we shall find the attractive power of the Karth 
 upon the Moon to be 21,777 times greater than that of the Moon upon the Earth. 
 
 613. We have thus stated the principal facts connected with 
 this complicated phenomenon, and the causes to which they are 
 generally attributed. And yet it is not certain that the philoso- 
 phy of tides is to this day fully understood. La Place, the great 
 French mathematician and astronomer, pronounced it one of the 
 most difficult problems in the whole range of celestial mechanics. 
 It is probable that the atmosphere of our globe has its tides, as 
 well as the waters j, but we have no means, as yet, for definitely 
 ascertaining the fact 
 
 CHAPTER XIY. 
 
 THE SEASONS DIFFERENT LENGTHS OF THE DAYS AND 
 NIGHTS. 
 
 614. THE vicissitudes of the seasons, and the unequal lengths 
 of the days and nights, are occasioned by the annual revolution 
 of the Earth around the Sun, with its axis inclined to the plane 
 of its orbit. The temperature of any part of the Earth's sur- 
 face depends mainly, if not entirely, upon its exposure to the 
 Sun's rays. 
 
 INCLINATION OF THE EABTfl's AXIS TO THE PLANK OF THE ECLIPTIC. 
 
 THE ECLIPTIC /5K 
 
 615. Whenever the Sun is above the horizon of any place, 
 that place is receiving heat ; when the Sun is below the horizon 
 it is parting with it, by a process which is called radiation. The 
 quantities of heat thus received and imparted in the course of 
 the year, must balance each other at every place, or the equi- 
 
 (H8. Is it certain that this subject is even yet well understood ? Remark of Laplace? 
 614. Cause of the seasons, and the unequal length cf the days and nights? Temperat'irc 
 of the Earth ? 615. When does any place gain heat, and when lose ? Upon what doet 
 
28S 
 
 ASTRONOM*. 
 
 librium of temperature would not be supported. Whenever tne 
 Sun remains more than twelve hours above the horizon of any 
 place, and less beneath, the general temperature of that place 
 will be above the mean state ; when the reverse takes place, the 
 temperature, for the same reason, will be below the mean state. 
 Kow, the continuance of the Sun above the horizon of any place, 
 depends entirely upon his declination, or altitude at noon. 
 
 616. About the 20th of March, when the Sun is in the ver- 
 nal equinox, and consequently has no declination, lie rises at six 
 in the morning and sets at six in the evening ; the day and night 
 are then equal, and as the Sun continues as long above our 
 horizon as below it, his influence must be nearly the same at the 
 same latitudes, in both hemispheres. 
 
 From the 20th of March to the 21st of June, the days grow 
 longer, and the nights shorter, in the northern hemisphere ; the 
 temperature increases, and we pass from spring to midsummer ; 
 while the reverse of this takes place in the southern hemisphere. 
 
 From the 21st of June to the 23d of September, the days 
 and nights again approach to equality, and the excess of tem- 
 perature in the northern hemisphere abote the mean state, grows 
 less, as also its defect in the southein ; so that, when the Sun 
 arrives at the autumnal equinox, the mean temperature is again 
 restored. 
 
 617. From the 23d of 
 September until the 21st of 
 December, our nights grow 
 longer and the days shorter, 
 and the cold increases as 
 before it diminished, while 
 we pass from autumn to 
 mid-winter, in the northern 
 hemisphere, and the inhabit- F 
 ants of the southern hemi- 
 sphere from spring to mid- 
 summer. 
 
 From the 21st of Dec. 
 to the 20th of March, the 
 cold relaxes as the days grow 
 longer, and we pass from 
 
 CAUSE OF THE SEASONS. 
 B 
 
 the length of the days depend? 616. How about the 20th of March? From March 
 520th to June 21st? From June 21st to September 23d ? 617. From September 23d to 
 I/uvsmber 21st ? From December 21st to March 20th? II( w with the seasons in the 
 
THE SEASONS. 289 
 
 the dreariness of winter to the mildness of spring, when the 
 seasons are completed, and the mean temperature is again 
 restored. The same vicissitudes transpire, at the same time, in 
 the southern hemisphere, but in a contrary order. Thus are 
 produced the four seasons of the year. 
 
 In the preceding cut, the Earth is shown in her orbit, with her axis inclined 23J$ e ; the 
 North Pole being towards the eye of the student. At A and B the Sun shines from pole 
 to pole, and the days and nights are equal in both hemispheres. On the right, the North 
 Pole is in the light, and we have summer in the northern hemisphere. On the left, the 
 reverse is the case. And the gradual shortening or lengthening of the days, and the 
 change of temperature, are produced by the passage of the Earth from one point to 
 another, with her axis thus inclined. 
 
 618. But I have stated not the only, nor, perhaps, the most 
 efficient cause in producing the heat of summer and the cold of 
 winter. If, to the inhabitants of the equator, the Sun were to 
 remain 16 hours below their horizon, and only 8 hours above it, 
 for every day of the year, it is certain they would never expe- 
 rience the rigors of our winter ; since it can be demonstrated, 
 that as much heat falls upon the same area from a vertical Sun 
 in 8 hours, as would fall from him, at an angle of 60, in 16 
 hours. 
 
 Now, as the Sun's rays fall most obliquely when the days are 
 shortest, and most directly when the days are Longest, these two 
 causes namely, the duration and intensity of the solar heat, 
 together, produce the temperature of the different seasons. The 
 reason why we have not the hottest temperature when the days 
 are longest, and the coldest temperature when the days are 
 shortest, but in each case about a mouth afterwards, appears to 
 be, that a body once heated, does not grow cold instantaneously, 
 but gradually, and so of the contrary. Hence, as long as more 
 heat comes from the Sun by day than is lost by night, the heat 
 will increase, and vice vcrsd. 
 
 BEGINNING AND LENGTH OF THB SEASONS. 
 
 Sun enters \3 (Winter begins 
 
 1849, December 21, 
 
 11. 
 
 7 
 
 Ml. 
 
 25 
 
 46 M. T. Wash. 
 
 u u 
 
 T (Spring " 
 
 1860, March 
 
 20, 
 
 8 
 
 50 
 
 38 
 
 " 
 
 (( 1C 
 
 C5 (Summer " 
 
 " June 
 
 21, 
 
 G 
 
 3 
 
 9 
 
 11 tC 
 
 u i( 
 
 == (Autumn " 
 
 " Sept. 
 
 22, 
 
 19 
 
 68 
 
 21 
 
 U (1 
 
 tl u 
 
 \3 (Winter " 
 
 " December 21, 
 
 18 
 
 '21 
 
 57 
 
 u it 
 
 outhern hemisphere ? 618. Is the simple fact that a place if enlightened by the Sun, a 
 ufficient cause for its being warm? What circumstance determines the intensity o' the 
 
 Bun's raya? Why, then, is it not warmest during the longest days, and on the cona-iiy 
 
 coldest during the shortest days ? How long will heat increase ? 
 
290 ASTRONOMY. 
 
 Sun in the Winter Signs ... . 89 1 30 52 
 
 " " Spring 92 21 6 81 
 
 " " Summer . . . . 93 13 55 22 
 
 " ' Autumn 89 17 23 26 
 
 " north of Equator (Spring and Summer) 186 11 1 53 
 
 " south " (Winter and Autumn) 178185418 
 
 Longest north of the Equator . . 7 16 7 85 
 Length of the tropical year beginning at ) 
 
 the winter solstice 1849, and ending at V ?65 5 56 11 
 
 the winter solstice 1850. ) 
 
 Mean or average length of the tropical year, 865 5 48 48 
 
 619. The north pole of the Earth is denominated the ekvaled 
 pole, because it is always about 23 above a perpendicular to 
 the plane of the ecliptic, and the south pole is denominated the 
 depressed pole, because it is about the same distance below such 
 perpendicular. 
 
 As the Sun cannot shine on more than one-half the Earth's surface at a time, it is 
 plain, that when the Earth is moving through that portion of its orbit which lies above 
 the Sun, the elevated pole is in the dark. This requires six months, that is, until the 
 Earth arrives at the equinox, when the elevated pole emerges into the light, and the 
 depressed pole is turned away from the Sun for the same period. Consequently, there 
 are six months day and six months night, alternately, at the poles. 
 
 620. When the Sun appears to us to be in one part of the 
 ecliptic, the Earth, as seen from the Sun, appears in the point 
 diametrically opposite. Thus, when the Sun appears in the ver- 
 nal equinox at the first point of Aries, the Earth is actually in 
 the opposite equinox at Libra. The days and nights are then 
 equal all over the world. (See the cut, pages 288 and 292.) 
 
 As the Sun appears to move up from the vernal equinox to the summer solstice, the 
 Earth actually moves from the autumnal equinox down to the winter solstice. The days 
 now lengthen in the northern hemisphere, and shorten in the southern. The Sun is now 
 over the north pole, where it is mid-day, and opposite the south pole, where it is midnight. 
 
 As the Sun descends from the summer solstice towards the autumnal equinox, the Earth 
 ascends from the winter solstice towards the vernal equinox. The summer days in the 
 northern hemisphere having waxed shorter and shorter, now become again of equal 
 length in both hemispheres. 
 
 621. While the Sun apears to move from the autumnal equi- 
 nox down to the winter solstice, the Earth passes up from the 
 vernal equinox to the summer solstice ; the south pole comes 
 into the light, the winter days continually shorten in the northern 
 hemisphere, and the summer days as regularly increase in length 
 in the southern hemisphere. 
 
 While the Sun appears again to ascend from its winte^ solstice 
 to the vernal equinox, the Earth descends from the Summer 
 solstice to the autumnal equinox. The summer days now shorten 
 
 619. Which is the elevated pole, and why? The depressed, and why? How are the 
 seasons produced? 620. How are the Earth and Sun situated in the ecliptic, with 
 reference to each other? What said of the Sun's apparent motion around the zodiac i 
 621. What further description of the Sun's apparent progress? 
 
THE SEASONS. 1291 
 
 in the southern hemisphere, and the winter days lengthen in the 
 northern hemisphere. 
 
 622. When the Sun passes the vernal equinox, it rises to the 
 arctic or elevated pole, and sets to the antarctic pole. When 
 the Sun arrives at the summer solstice, it is noon at the north 
 pole, and midnight at the south pole. When the Sun passes the 
 autumnal equinox, it sets to the north pole, and rises to the 
 south pole. When the Sun arrives at the winter solstice, it is 
 midnight at the north pole, and noon at the south pole ; and 
 when the Sun comes again to the vernal equinox, it closes the 
 day at the south pole, and lights up the morning at the north 
 pole. 
 
 There would, therefore, be 186 days during which the Sun 
 would not set at the north pole, and an equal time during which 
 he would not rise at the south pole ; and 17 8|- days in which he 
 would not set at the south pole, nor rise at the north pole. 
 
 623. At the arctic circle, 23 2t' from the pole, the longest 
 day is 24 hours, and goes on increasing as you approach the 
 pole. In latitude 67 18' it is 30 days ; in lat. 69 30' it is 60 
 days, &c. The same takes place between the antarctic circle 
 and the south pole, with the exception, that the day in the same 
 latitude south is a little shorter, since the Sun is not so long 
 south of the equator, as at the north of it. In this estimate no 
 account is taken of the refraction of the atmosphere, which, as 
 we shall see hereafter, increases the length of the day, by mak- 
 ing the Sun appear more elevated above the horizon than it 
 really is. All these apparent motions of the Sun are due to the 
 inclination of the Earth's axis (or the obliquity of the ecliptic), 
 and her revolution around the Sun. 
 
 The following cut represents the inclination of the Earth's axis to its orbit in every 
 one of the twelve signs of the zodiac, and consequently for each month in the year. 
 It is such a view as a beholder would have, situated in the north pole of the ecliptic, at 
 some distance from it, and consequently, is a perpendicular view, the north pole of the 
 Earth being towards us. The Sun enters the sign Aries, or the vernal equinox, on the 
 20th of March, when the Earth enters Libra, and when her axis inclines neither towards 
 the Sun, nor from it, but stands exactly sideways to it; so that the Sun then shines 
 equally upon the Earth from pole to pole, and the days and nights are everywhere equal. 
 This is the beginning of the astronomical year; it is also the beginning of day at the 
 north pole, which is just coming into light and the end of day at the south pole, which 
 is just going into darkness. 
 
 By the Earth's orbitual progress, the Sun appears to enter the second sign, Taurus, 
 on the 20th of April, when the north pole has sensibly advanced into the light, while the 
 Bouth pole has been declining from it; whereby the days become longer than the nights 
 In the northern hemisphere, and shorter in the southern. 
 
 On the 21st of May, the Sun appears to enter the sign Gemini, when the north pole 
 
 622. How are the light and darkness of the poles affected by the Sun's apparent motion ? 
 623. What said of the length of the days within the arctic circle ? In latitude 67 18' ? 
 In latitude 69- 80' ? How at the other pole ? To what are these various apoarenl 
 (notions of the Sun really due ? 
 
 U.G. 13 
 
292 
 
 ASTRONOMY. 
 
 has advanced considera- PHILOSOPHY OP THE SEASONS.* 
 
 bly further into the light, 
 
 while the south pole has 
 
 proportionally declined 
 
 from It; the summer 
 
 days are now waxing 
 
 longer in the northern 
 
 hemisphere, and the 
 
 nights shorter. 
 
 The 21st of June, when 
 the Sun enters the sign 
 Cancer, is the first day 
 of summer in the astro- 
 nomical year, and the 
 longest day in the north- 
 ern hemisphere. The 
 north pole now has its 
 jreatest inclination to 
 the Sun, the light of 
 which, as is shown by 
 the boundary of light and 
 darkness, in the figure, 
 extends to the utmost 
 verge of the Arctic Cir- 
 cle ; the whole of which 
 is included in the enlight^ 
 ened hemisphere of the 
 Earth, and enjoys, at 
 this season, constant day 
 during the complete revo- 
 lution of the Earth on its 
 axis. The whole of the Northern Frigid Zone is now in the circle of perpetual illumi- 
 nation. 
 
 On the 23d of July, the Sun enters the sign Leo, and as the line of the Earth's axis always 
 continues parallel to itself, the boundary of light and darkness begins to approach nearer 
 to the poles, and the length of the day in the northern hemisphere, which had arrived 
 at its maximum, begins gradually to decreose. On the 23d of August, the Sun enters the 
 sign Virgo, increasing the appearances mentioned in Leo. 
 
 On the 23d of September, the Sun enters Libra, the first of the autumnal signs, when 
 the Earth's axis having the same inclination as it had in the opposite sign, Aries, is 
 turned neither from the Sun, nor towards it, hut obliquely to it, so that the Sun again 
 now shines equally upon the whole of the Earth's surface from pole to pole. The days 
 and nights are once more of equal length, throughout the world. 
 
 On the 23d of October, the Sun enters the sign Scorpio ; the days visibly decrease 
 in length in the northern hemisphere, and increase in the southern. 
 
 On the 22d of November the Sun enters the sign Sagittarius, the last of the autumnal 
 signs, at which time the boundary of light and darkness is at a considerable distance 
 from the north pole, while the south pole has proportionally advanced into the light; the 
 length of the day continues to increase in the southern hemisphere, and to decrease in 
 the northern. 
 
 On the 21st of December, which is the period of the winter solstice, the Sun enters the 
 sign Capricorn. At this time, the north pole of the Earth's axis is turned from the 
 Sun, into perpetual darkness; while the south pole, in its turn, is brought into the light 
 of the Sun, whereby the whole Antarctic region comes into the circle of perpetual illumi- 
 nation. It is now that the southern hemisphere enjoys all those advantages with which 
 the northern hemisphere was favored on the 21st of June ; while the northern hemi- 
 sphere, in its turn, undergoes the dreariness of winter, with short days and long 
 nights. 
 
 * This diagram and the accompanying explanations should be carefully studied till 
 '^ey are thoroughly understood by the learner. The cause of the seasons and of the 
 uuv'aual lengths of the days and nights, is a matter of which no professedly educated 
 person ought to be ignorant, or to entertain confused and indefinite notions. By all 
 inenns iet this point be studied till the student can tell the cause of every particular phe- 
 nomenon of the seasons and the length of the days, without any particular interr> 
 Eution. 
 
THE HARVEST MOON AND HORIZONTAL MOON. 293 
 
 624. By carefully observing the figure, it may be seen that 
 the orbit of the Earth is slightly elliptical, that the Sun is to 
 the left of the center, and that consequently, the Earth is nearer 
 the San on the 21st of December, than on the opposite side of 
 the ecliptic, on the 21st of June. This may seem strange to the 
 learner, that we should have our winter when nearest the Sun, 
 and our summer when most distant ; but it must be remembered 
 that the temperature of any particular part of the Earth is 
 not so much affected by the distance of the Sun, as by the direct- 
 ness or obliquity of his rays. Hence, though we are farther 
 from the Sun on the 21st of June than on the 21st of December, 
 yet, as the north pole of the Earth is turned more directly into 
 the light at that time, so that the Sun's rays strike her surface 
 less obliquely than in December, we have a higher temperature 
 at that period, though at a greater distance from the Sun. 
 
 625. The difference, however, between the aphelion and peri- 
 helion distances of the Earth is so slight, in comparison with the 
 whole distance, as scarcely to cause a perceptible difference in the 
 amount of light received at her respective positions. The eccen- 
 tricity of the Earth's orbit, or the distance of the Sun from its 
 center, is only about 1,618,000 miles, so that the variation is 
 only 3,236,000 miles, or about one-thirtieth of the mean distance. 
 The true orbit of the Earth could not be distinguished from a 
 circle. 
 
 The only effect of the eccentricity of the Earth's orbit upon her temperature is, that 
 she has probably a greater degree of heat, during summer in the southern hemisphere, 
 when the Earth is at her perihelion, than we ever have at the north iu the same lati- 
 tude. But this difference must be very slight, if indeed it is at all perceptible. 
 
 CHAPTER XY. 
 THE HAKVEST MOON AND HORIZONTAL MOON, 
 
 626. THE daily progress of the Moon in her orbit, from west to 
 east, causes her to rise, at a mean rate, 48 minutes and 44 
 seconds later every day than on the preceding. But in places 
 of considerable latitude, a remarkable deviation from this rule 
 
 624. What said of the form of the Earth's orbit ? When arc we nearest the Sun \ 
 Why is it not then the warmest in the United States? 625. What is the amount of th 
 Earth's variation in distance from the Sun ? What effect upon the light and heat of the 
 Earth If 626. Subject of this chapter? Mean rate of the Moon's daily delay \a Hairy 
 
294 ASTRONOMf. 
 
 takes place, especially about the time of Harvest, when the full 
 Moon rises to us for several nights together, only from 18 to 25 
 minutes later in one day, than on that immediately preceding. 
 From the benefit which her light affords, in lengthening out the 
 day, when the husbandmen are gathering in the fruits of the 
 Earth, the full Moon, under these circumstances, has acquired 
 the name of Harvest Moon. 
 
 It is believed that this fact was observed by persons engaged in agriculture, at a much 
 earlier period than that in which it was noticed by astronomers. The former ascribed it 
 to the goodness of the Deity ; not doubting but that he had so ordered it for their advan- 
 tage. 
 
 621. About the equator, the Moon rises throughout the year 
 with nearly the equal intervals of 48f minutes ; and there the 
 harvest Moon is unknown. At the polar circles, the autumnal 
 full Moon, from her first to her third quarter, rises as the Sun 
 sets ; and at the poles, where the Sun is absent during one-half 
 of the year, the winter full Moons, from the first to the third 
 quarter, shine constantly without setting. 
 
 By this, it is not meant that the Moon continues futt from her first to her third quar- 
 ter ; but that she never sets to the North Polar regions, when, at this season of the year, 
 she is within 90* of that point in her orbit, where she is at her full. In other words, as 
 the Sun illumines the south pole during one-half of its yearly revolution, so the Moon, 
 being opposite to the Sun at her full, must illumine the opposite pole, during half of her 
 revolution about the Earth. The phenomenon of the Harvest Moon may be thus exem- 
 plified by means of the globe. 
 
 Rectify the globe to the latitude of the place, put a patch or piece of wafer in the eclip- 
 tic, on the point Aries, and mark every 12* preceding and following that point, to the 
 number often or twelve marks on each side of it; bring the equinoctial point marked by 
 the wafer to the eastern edge of the horizon, and set the index to 12 ; turn the globe 
 westward till the other marks successively come to the horixon, and observe the hours 
 passed over by the index ; the intervals of time between the marks coming to the horizon, 
 will show the diurnal difference of time between the Moon's rising. If these marks be 
 Drought to the western edge of the horizon in the same manner, it will show the diurnal 
 difference between the Moon's setting. 
 
 From this problem it will also appear, that, when there is the least difference between 
 the times of the Moon's rising, there will be the greatest difference between the tunes of 
 her setting, and the contrary. 
 
 The reason why you mark every 12" is, that the Moon gains 12* 11' on the apparent 
 course of the Sun every day, and these marks serve to denote the place of the Moon 
 from day to day. It is true, this process supposes that the Moon revolves in the plane 
 of the ecliptic, which is not the case ; yet her orbit so nearly coincides with the ecliptic 
 (differing only 5 9' from it), that they may, for the convenience of illustration, be con- 
 sidered as coinciding ; that is, we may take the ecliptic for the representative of the 
 Moon's orbit. 
 
 628. The different lengths of the lunar night, at different lati- 
 tudes, is owing to the different angles made by the horizon and 
 different parts of the Moon's orbit ; or, in other words, by the 
 
 What remarkable deviation? What is the Moon then called, and why? How anciently 
 was this phenomenon observed? To what attributed? 627. Is the Harvest Moon 
 known at the equator? How at the Polar circles ? At the poles? Does she there exhi- 
 bit her usual phases ? Can you illustrate the phenomenon of the Harvest Moon by u 
 globe? 628. To what is the different lengths of the lunar nights attributable? 
 
THE HARVEST MOON AND HORIZONTAL MOON. 295 
 
 Moon's orbit lying sometimes more oblique to the horizon than 
 at others. 
 
 In the latitude of London, for example, as much of the ecliptic rises ab mt Pisces anl 
 Aries in two hours as the Moon goes through in six days ; therefore, while the Moon is in 
 these signs, she differs but two hours in rising for six days together ; that is, one day 
 with another, she rises about 20 minutes later every day than on the preceding. 
 
 629. The parts or signs of the ecliptic which rise with the 
 smallest angles, set with the greatest ; and those which rise with 
 the greatest, set with the least. And whenever this angle is 
 least, a greater portion of the ecliptic rises in equal times than 
 when the angle is larger. Therefore, when the Moon is in those 
 signs which rise or set with the smallest angles, she rises or sets 
 with the least difference of time ; but when she is in those signs 
 which rise or set with the greatest angles, she rises or sets with 
 the greatest difference of time. 
 
 Let the globe, for example, be rectified to the latitude of New York, 40' 42' 40', with 
 Cancer on tho meridian, and Libra rising in the east. In this position, the ecliptic has a 
 high elevation, making an angle with the horizon of 72j e . 
 
 But let the globe be turned half round on its axis, till Capricorn comes to the meridian, 
 and Aries rises in the east, then the ecliptic will have a low elevation above the horizon, 
 making an angle with it of only 25 J$. This angle is 47 less than the former angle, and 
 is equal to the distance between the tropics. 
 
 630. In northern latitudes, the smallest angle made by the 
 ecliptic and horizon is when Aries rises ; at which time Libra 
 sets ; the greatest is, when Libra ijses and Aries sets. The eclip- 
 tic rises fastest about Aries, and slowest about Libra. Though 
 Pisces and Aries make an angle of only 25-^ with the horizon 
 when they rise, to those who live in the latitude of New York, 
 yet the same signs, when they set, make an angle of 72^-. The 
 daily difference of the Moon's rising, when in these signs, is, in 
 New England, about 22 minutes ; but when she is in the oppo- 
 site signs, Yirgo and Libra, the daily difference of her rising is 
 almost four times as great, being about one hour and a quarter 
 
 631. As the Moon can never be full but when she is opposite 
 to the Sun, and the Sun is never in Virgo or Libra except in 
 our autumnal months, September and October, it is evident that 
 the Moon is never full in the opposite signs, Pisces and Aries, 
 except in those two months. We can, therefore, have only two 
 full Moons in a year, which rise, for a week together, very near 
 the time of sunset. The former of these is called the Harvest 
 Moon, and the latter, the Hunter's Moon. 
 
 629. What said of the angles under which the signs rise and set ? What result follows 
 as to time of the Moon's rising and setting? How illustrate by globe ? 630. When is 
 the angle smallest in northern latitudes? When greatest? What difference of angle a 
 the rising and setting of Pisces? Daily difference of the Moon's rising? When in Piseee 
 and Aries? What when in Virgo and Libra? 631. Why have we not more than OH* 
 Uurvest, and one Hunter's Moon in a year? 
 
296 . AaTRGNOMY. 
 
 632. Although there can be but two full Moons in the year 
 that rise with r,o little variation of time, yet the phenomenon 
 of the Moon's rising for a week together so nearly at the same 
 time, occurs every month, in some part of her course or the 
 other. 
 
 In Winter, the signs Pisces and Aries rise about noon ; hence the rising of the Moon 
 is not then regarded nor perceived. 
 
 In Spring, these signs rise with the Sun, because he is then in them ; and as the Moon 
 changes while passing through the same sign with the Sun, it must then be the change, 
 and hence invisible. 
 
 In Summer, they rise about midnight, when the Moon, is in her third quarter. On 
 account of her rising so late, and giving but little light, her rising passes unobserved. 
 
 633. To the inhabitants at the equator, the north and south 
 poles appear in the horizon, and therefore the ecliptic makes the 
 same angle southward with the horizon when Aries rises, as it 
 does northward when Libra rises ; consequently the Moon rises 
 and sets not only with angles nearly equal, but at equal intervals 
 of time, all the year round ; hence, there is no harvest Moon at 
 the equator. The farther any place is from the equator, if it be 
 not bey-ond the polar circles, the angle which the ecliptic makes 
 with the horizon gradually diminishes when Pisces and Aries rise. 
 
 634. Although, in northern latitudes, the autumnal full Moons 
 are in Pisces and Aries ; yet in southern latitudes it is just the 
 reverse, because the seasons :.re so : for Yirgo and Libra rise 
 at as small angles with the horizon in southern latitudes as Pisces 
 and Aries do in the northern ; and therefore the harvest Moons 
 are just as regular on one side of the equator as on the other. 
 
 At the polar circles, the full Moon neither rises in summer, nor sets in winter. For the 
 winter full Moon being as high in the ecliptic as the summer Sun, she must continue while 
 passing through the northern signs, above the horizon ; and the summer full Moon, being 
 as low in the ecliptic as the winter Sun, can no more rise, when passing through the 
 southern signs, than he does. 
 
 635. The great apparent magnitude of the Moon, and indeed 
 of the Sun, at rising and setting, is a phenomenon which has 
 greatly embarrassed almost all who have endeavored to account 
 for it. According to the ordinary laws of vision, they should 
 appear to be least when nearest the horizon, being then farthest 
 from the eye ; and yet the reverse of this is found to be true. 
 The apparent diameter of the Moon, when viewed in the horizon 
 by the naked eye, is two or three times larger than when at the 
 altitude of thirty or forty degrees ; and yet when measured by 
 an instrument her diameter is not sensibly increased. 
 
 682. Does not the Moon rise with little variation for several nights In succession, 
 every month? Why not always perceived? 633. Why is there no ffarvrt Moon at 
 the equator ? 634. What said of these lunar phenomena in the Southern .lornisphere ? 
 685. What said of the apparent diameter of the Moon in the horizon? How wheu 
 
REFRACTION AND TWILIGHT. 297 
 
 Both the Sun and the Moon really subtend a greater angle when on the meridian, than 
 they do in the horizon ; because they are then actually nearer the place of the spectator 
 by the whole semi-diameter of the Earth ; and one reason why they appear largest in 
 the horizon is, that they are then compared with terrestrial objects, with whose magni- 
 tude we are acquainted. 
 
 This apparent increase of magnitude in the horizontal Moon, is chiefly an optical illu- 
 *ion, produced by the concavity of the heavens appearing to the eye to be a less portion 
 of a spherical surface than a hemisphere. The eye is accustomed to estimate the dis- 
 tance between any two objects in the heavens by the quantity of sky that appears to lie 
 between them ; as upon the Earth we estimate it by the quantity of ground that lies 
 between them. Now when the Sun or Moon is just emerging above the eastern horizon, 
 or sinking beneath the western, the cLifttance of the intervening landscape over which 
 they are seen, contributes, together with the refraction of the atmosphere, to exaggerate 
 our estimate of their real magnitudes. 
 
 THE HORIZONTAL MOON. 
 
 636. Both the Sun and Moon are sometimes seen to be elon, 
 gated horizontally, when near the horizon. This is often the case 
 when the atmosphere is very dense. The cause of this pheno- 
 menon is this : All celestial bodies in the horizon are more or 
 less elevated by atmospherical refraction (See page 300) ; and 
 the amount of this apparent elevation depends somewhat upon 
 the density of the atmosphere as well as upon the altitude of the 
 object. When, therefore, the Sun or Moon are near the horizon, 
 and viewed through a dense atmosphere, the refraction is great- 
 est ; and as their lower limb is seen through a denser stratum of 
 atmosphere than their upper limb, its apparent elevation is 
 greater, and the object seems to be flattened, while its horizontal 
 diameter is not sensibly diminished. 
 
 This phenomenon and its cause may be easily illustrated by a diagram. 
 
 CHAPTER XYI. 
 
 REFRACTION AND TWILIGHT. 
 
 637. THE rays of light, in passing out of one medium into 
 another of a greater density, deviate from a straight course, and 
 are bent towards a perpendicular to that course ; and if the 
 density of the latter medium continually increase, the rays of 
 
 measured ? When do they subtend the greater angle ? Why appear largest when in 
 the horizon? What other explanation given? 636. What is meant by a Horiaonttil 
 Moon? The cause of this phenomenon? 637. What is meant by the refraction of 
 light? What principles govern it? 
 
298 
 
 ASTRONOMY. 
 
 LIGHT REFRACTED BY WATER. 
 
 D G A 
 
 light in passing through it, will deviate more and more from a 
 right line as they pass downwards, or towards the eye of the 
 observer. 
 
 638. As air and water are both transparent, but of different 
 densities, it follows that, when light passes obliquely from one 
 to the other, it will be 
 refracted. If it pass 
 from the air into the 
 water, it will be refract- 
 ed towards a ptrpendicur 
 lar. 
 
 Here the ray A C strikes the 
 water perpendicularly, and passes 
 directly through to B without be- 
 ing refracted. But the ray D 
 strikes the water at C obliquely ; 
 and instead of passing straight 
 through to E, is refracted at C, 
 and reaches the bottom of the water at P. If, therefore, a person were to receiye tha 
 ray into the eye at F, and to judge of the place of the object from which the light ema- 
 nates from the direction of the ray C F, he wonld conclude that he saw the object at Q-, 
 unless he made allowance for the refraction of the light at C. 
 
 F 
 
 LIGHT PROCEEDING FROM WATER. 
 
 B 
 
 
 639. When light passes 
 obliquely from a denser 
 to a rarer medium, as 
 from water into air, it is 
 refracted from a perpen- 
 dicular towards a horizon- 
 tal. 
 
 Here the lamp A shines up 
 through water into air. The ray 
 that strikes the surface perpen- 
 dicularly passes on to B without 
 oeing refracted ; but the other rays 
 
 that leave the water obliquely are refracted toward a horizontal direction, In proportion 
 to their distance from the perpendicular; or, in other words, in proportion to the 
 obliquity of their contact with the surface of the water. 
 
 640. Ill consequence of the refraction of light towards a hori- 
 zontal direction, in passing from water into air, a pole, half of 
 which is in the water, seems bent at the surface, and the lower 
 end seems nearer the surface than it really is. For the same 
 reason, the bottom of a river seems higher, if seen obliquely, than 
 it really is ; and the water is always deeper than we judge it 
 to be. 
 
 688. How refracted by air and water ? 
 rarer media? 640. Effect of refraction upon objects seen un 
 
 639. How when light passes from denser to 
 n objects seen under water? 
 
REFRACTION AND TWILIGHT. 
 
 299 
 
 In this cut, the oar, the blade of 
 Thich is in the water, seems bent at the 
 uurface of the water. The rays of light 
 passing from the part under water to 
 the surface at D, are refracted toward 
 a horizontal direction at that point, 
 and received into the eye of the ob- 
 server at B, who, judging of the posi- 
 tion of the immersed portion of the oar 
 from the direction of the rays D B, 
 locates the blade of the oar at C; thus 
 reversing the effect illustrated at 
 
 EFFECT OF REFRACTION- 
 
 641. The refracting power of different transparent substances 
 depends mainly upon their density. Water refracts more than 
 air, glass more than water, and diamond most of all. But the 
 angle of incidence, or the obliquity of the contact of the rays 
 with the denser substance, has also much to do in determining 
 the amount of refraction. 
 
 EFFECT OF REFRACTION 
 
 642. By the aid of refraction, 
 we may see objects that are 
 actually behind an opaque or 
 intransparent body. 
 
 Here the piece of money at A, at the 
 bottom of the cup, would be invisible to 
 the behoiuc. '* B, if the cup was empty, 
 as the light from the money would pass 
 from A to C; but when the oup is filled 
 with water, the light is refracted to B, and 
 the beholder sees the money apparently 
 atD. 
 
 643. By the 
 law of refrac- 
 tion, light has 
 been found to 
 consist of a com- 
 bination of co- 
 lors. By pass- 
 ing a beam of 
 light through a Blue... 
 triangular piece YeuJll 
 
 Of flint glaSS grange 
 
 called a prism, 
 it is seen that 
 some parts of 
 
 REFRACTION BY A PRISM. 
 
 A 
 
 64! . Upon what does the refracting power of different transparent media depend ' 
 642. What other effect of refraction? 643. What discovery by refraction? HOT. 
 
 13* 
 
300 
 
 ASTRONOMY. 
 
 the light are more refrangible than others, so that the light is 
 analyzed, or separated into its component parts or elements. 
 
 Let a ray of light from the Sun be admitted through a hole in the window shutter, A, 
 into a room from which all other light is excluded ; it will form on a screen placed a little 
 distance in front, a circular image, B, of white light. Now iirterpose near the shutter a 
 glass prism, C, and the light, in passing through it, will not only be refracted in the same 
 direction, both when it enters the prism and when it leaves it, but the several rays 01 
 which white light is composed will be separated, and will arrange in regular order on the 
 screen, immediately above the image B, which will disappear. The violet ray, it will be 
 seen, is most refracted, and the red least ; the whole forming on the scale an elongated 
 image of the Sun, called the solar spectrum. Johnston. 
 
 644. It is the refraction of the clouds that gives the sky its 
 beautiful colors morning and evening ; and the refracting power 
 of the rain-drops produces the beautiful phenomenon of the rain- 
 bow. 
 
 ATMOSPHERICAL REFRACTION. 
 
 645. The refracting power of the atmosphere produces many 
 curious phenomena. Sometimes ships are seen bottom upwards 
 in the air, single or double. At other times, objects really below 
 the horizon, as ships or islands, seem to rise up, and to come dis- 
 tinctly in view. 
 
 646. A very important effect of refraction, as it relates to 
 astronomy, is, that it more or less affects the apparent piaces of 
 all the heavenly bodies. As the light coming from them strikes 
 the atmosphere obliquely, and passes downward through it, it is 
 refracted or bent towward the Earth, or toward a perpendicular. 
 And as we judge of the position of the object by the direction 
 of the ray when it enters the eye, we place objects higher in the 
 heavens than they really are. 
 
 ATMOSPHERICAL REFRACTION. 
 
 Let A, in the cut, repre- 
 sent the Earth ; B, the at- 
 mosphere ; C C, the visible 
 horizon ; and the exterior 
 circle the apparent con- 
 cave of the heavens. Now, 
 as the light passes from 
 the stars, and strikes the 
 atmosphere, it is seen to 
 curve downward, because 
 it strikes the atmosphere 
 obliquely ; and the air in- 
 sreases in density as we 
 approach the Earth. But 
 as the amount of refraction depends not only upon the density, but also upon the obli- 
 quity of the contact, it is seen that the refraction is greatest at the horizon, and gradu- 
 ally diminishes till the object reaches the zenith, when there is nc obliquity, and the refrac- 
 
 344 What other effects of refraction ? 645. Atmospherical refraction ? Efftcu on 
 terrestrial objeots ': <. 46. Upon apparent places of stars, Ac. ? 
 
REFRACTION AND TWILIGHT. 301 
 
 (Ion whdly ceases. The dark lines in the cut show the true, and the dotted the apparent 
 oositions. 
 
 In the cut, the depth of the atmosphere, as compared with the globe, is greatly exag- 
 gerated. Even allowing it to be 50 miles deep, it is only-J-th of the semi-diameter of the 
 <?iobe, which is equal to only abouty 1 ^ th of an inch upon a common 13-inch globe. But 
 ., was necesary to exaggerate, in order to illustrate the principle. 
 
 647. The amount of displacement of objects in the horizon, 
 ty atmospherical refraction, is about 33', or a little more than 
 .he greatest apparent diameter of either the Sun or Moon. It 
 /allows, therefore, that when we see the lower edge of either 
 apparently resting on the horizon, its whole disc is in reality below 
 it ; and would be entirely concealed by the convexity of the 
 Earth, were it not for refraction. 
 
 648. Another effect of refraction is, that the Sun seems to 
 rise about three minutes earlier, and to set about three minutes 
 later, on account of atmospherical refraction, than it otherwise 
 would ; thus adding about six minutes, on an average, to the 
 length of each day. 
 
 The atmosphere is said to be so dense about the North Pole as to bring the Sun above 
 the horizon some days before he should appear, according to calculation. In 1596, some 
 Dutch navigators, who wintered at Nova Zembla, in latitude 76, found that the Sun began 
 to be visible 17 days before it should have appeared by calculation ; and Kepler computes 
 that the atmospheric refraction must have amounted to 5, or 10 times as much as with us. 
 
 649. The twilight of morning and evening is produced partly 
 by refraction, but mainly by reflection, lu the morning, when 
 the Sun arrives within 18 of the horizon, his rays pass over 
 our heads into the higher region of the atmosphere, and are 
 thence reflected down to the Earth. The day is then said to 
 be dawn, and the light gradually increases till sunrise. In the 
 evening, this process is reversed, and the twilight lingers till the 
 Sun is 18 below the horizon. There is thus more than an hour 
 of twilight both morning and evening. 
 
 In the arctic regions, the Sun is never more than 18* below the horizon ; so that the 
 twilight continues during the whole night. 
 
 650. In making astronomical observations, for the purposes 
 of navigation, &c., allowance has to be made for refraction, 
 according to the altitude of the object, and the state of the 
 atmosphere. For this pirpose tables are constructed, showing 
 the amount of refraction :or every degree of altitude, from the 
 horizon to the zenith. 
 
 647. Amount of displacement of celestial objects by Refraction? What follows? 
 643. Influence of refraction on length of days? How about the North Pole ? 649. Cause 
 cfttciliffhtt 650. What allowance r or refraction ? Tables? 
 
302 ASTRONOMY. 
 
 CHAPTER XYII. 
 
 AURORA BOREALIS AND PARALLAX. 
 
 651. THE sublime and beautiful phenomena presented by the 
 Aurora Borealis, or northern lights, as they are called, have been 
 in all ages a source of admiration and wonder alike to the pea- 
 sant and the philosopher. In the regions of the north (and 
 indeed in many other places) they are regarded by the ignorant 
 with superstitious dread, as harbingers of evil ; while all agree 
 in placing them among the unexplained wonders of nature. 
 
 These lights, or meteoric coruscations, are more brilliant in the arctic regions, appear- 
 ing mostly in the winter season and in frosty weather. They commonly appear at twi- 
 light near the horizon, and sometimes continue in that state for several hours without 
 any sensible motion ; after which they send forth streams of stronger light, shooting 
 with great velocity up to the zenith, emulating, not unfrequeatly, the lightning in vivid- 
 ness, and the rainbow in coloring ; and again, silently rising in a compact majestic arch 
 of steady white light, apparently durable and immovable, and yet so evanescent, that 
 while the beholder looks upon it, it is gone. 
 
 At other times they cover the whole hemisphere with their flickering and fantastic 
 coruscations. On these occasions their motions are amazingly quick, and they astonish 
 the spectator with rapid changes of form. They break out in places where none were 
 seen before, skimming briskly along the heavens ; then they are suddenly extinguished, 
 leaving behind an uniform dusky track, which, again, is brilliantly illuminated in the same 
 manner, and as suddenly left a dull blank. Some nights they assume the appearance of 
 vast columns ; exhibiting on one side tints of the deepest yellow, and on the other, 
 melting away until they become undistinguishable from the surrounding sky. They 
 have generally a strong tremulous motion from end to end, which continues till the whole 
 vanishes. 
 
 652. Maupertius relates, that in Lapland, " the sky was 
 sometimes tinged with so deep a red that the constellation Orion 
 looked as though it were dipped in blood, and that the people 
 fancied they saw armies engaged, fiery chariots, and a thousand 
 prodigies." Gmelin relates, that, "in Siberia, on the confines 
 of the icy sea, the spectral forms appear like rushing armies ; 
 and that the hissing, crackling noises of those aerial fireworks 
 so terrify the dogs and the hunters, that they fall prostrate on 
 the ground, and will not move while the raging host is passing.' 
 
 Kerguelen describes " the night between Iceland and the Ferro 
 Islands, as brilliant as the day" the heavens being on fire with 
 flames of red and white light, changing to columns and arches, 
 and at length confounded in a brilliant chaos of cones, pyramids, 
 radii, sheaves, arrows, and globes of fire. 
 
 653. But the evidence of Captain Parry is of more value 
 
 651. What said of the Aurora Borealis t How regarded by the ignorant? Wherr- 
 most brilliant? In what weather? Describe? 662. Observations of MaurertitA 
 Gmtlin, and Kerguelen ? 653. Observations of Capt. Parry f 
 
AClAORA BOREALIS AND PARALLAX. 303 
 
 than that of the earlier travelers, as he examined the phenomena 
 under the most favorable circumstances, during a period of 
 twenty-seven consecutive months, and because his observations 
 are uninfluenced by imagination. He speaks of the shifting 
 figures, the spires and pyramids, the majestic arches, and the 
 sparkling bands and stars which appeared within the arctic cir- 
 cle, as surpassing his powers of description. They are, indeed, 
 sufficient to enlist the superstitious feelings of any people not 
 fortified by religion and philosophy. 
 
 654. The colors of the polar lights are of various 'tints. The 
 rays or learns are steel grey, yellowish grey, pea green, celandine 
 green, gold yellow, violet blue, purple, sometimes rope red, crim- 
 son red, blood red, greenish red, orange red, and lake red. The 
 arches are sometimes nearly black, passing into violet blue, grey, 
 gold yellow, or white bounded by an edge of yellow. The luster 
 of these lights varies in kind as well as intensity. Sometimes it 
 is pearly, sometimes imperfectly vitreous, sometimes metallic. 
 Its degree of intensity varies from a very faint radiance to a 
 light nearly equaling that of the Moon. 
 
 655. Many theories have been proposed to account for this 
 wonderful phenomenon, but there seems to be none which is 
 entirely satisfactory. One of the first conjectures on record 
 attributes it to inflammable vapors ascending from the Earth 
 into the polar atmosphere, and there ignited by electricity. Dr. 
 Halley objects to this hypothesis, that the cause is inadequate 
 to produce the effect. He was of opinion that the poles of the 
 Earth were in some way connected with the aurora ; that the 
 Earth was hollow, having within it a magnetic sphere, and that 
 the magnetic effluvia, in passing from the north to the south, 
 might become visible in the northern hemisphere. 
 
 656. That the aurora borealis is, to some extent, a magnetical 
 phenomenon, is thought, even by others, to be pretty clearly 
 established by the following considerations : 
 
 (1.) It has been observed, that when the aurora appears near 
 the northern horizon in the form of an arch, the middle of it is 
 not in the direction of the true north, but in that of the mag 
 netic needle at the place of observation ; and that when the 
 arch rises towards the zenith, it constantly crosses the heavens 
 at right angles, not to the true magnetic meridian. 
 
 654. What said of the colors, &c., of these polar lights? 655. Is there a satisfactorj 
 explanation of these phenomena? What conjecture? Dr. Halley's objection? His owr 
 singular opinion ? 656. What, evidences that the Aurora Jlorealis is of magnetu 
 origin ? 
 
304 ASTRONOMY. 
 
 (2.) When the beams of the aurora shoot up so as to pass 
 whe zenith, which is sometimes the case, the point of their con- 
 vergence is in the direction of the prolongation of the dipping 
 needle at the place of observation. 
 
 (3.) It has also been observed, that during the appearance of 
 an active and brilliant aurora, the magnetic needle often becomes 
 restless, varies sometimes several degrees, and does not resume 
 its former position until after several hours. 
 
 From these facts, it has been generally inferred that the aurora is in some way con- 
 nected with the magnetism of the Earth ; and that the simultaneous appearance ef the 
 meteor, and the disturbance of the needle, are either related as cause and effect, or as 
 the common result of some more general and unknown cause. 
 
 657. Dr. Young, in his lectures, is very certain that the phe 
 nomenon in question is intimately connected with electro-mag- 
 netism, and ascribes the light of the aurora to the illuminated 
 agency of electricity upon the magnetical substance. 
 
 It may be remarked, in support of the electro-magnetic theory, that in magnetism, the 
 agency of electricity is now clearly established, and it can hardly be doubted that the 
 phenomena both of electricity and magnetism are produced by one and the same cause ; 
 inasmuch as magnetism may be induced by electricity, and the electric spark has been 
 drawn from the magnet. 
 
 658. Sir John Herschel also attributes the appearance of the 
 aurora to the agency of electricity. This wonderful agency, says 
 he, which we see in intense activity in lightning, and in a feebler 
 and more diffused form traversing the upper regions of the 
 atmosphere in the northern lights, is present, probably, in 
 immense abundance in every form of matter which surrounds us, 
 but becomes sensible, only when disturbed by excitements of 
 peculiar kinds. 
 
 PARALLAX OF THE HEAVENLY BODIES. 
 
 659. Parallax is the difference between the altitude of any 
 celestial object seen from the Earth's surface, and the altitude 
 of the same object seen at the same time from the Earth's cen- 
 ter ; or it is the angle under which the semi-diameter of the 
 Earth would appear, as seen from the object. 
 
 The true place of a celestial body is that point of the heavens 
 in which it would be seen by an eye placed at the center of the 
 Earth. The apparent place is that point of the heavens where 
 the body is seen from the surface of the Earth. The parallax 
 
 657. Dr. Young's opinion? What remark in support of his views? 653. Sir John 
 Herschel's opiniou ? 659. Parallax? True place of a celestial body? Apparent? 
 When parallax greatest? Least? Called what, and why ? What objects the greatest 
 parallax ? 
 
AURORA BOREAL1S AND PARALLAX. 305 
 
 of a heavenly body is greatest when in the horizon, and is 
 thence called the horizontal parallax. Parallax decreases as the 
 body ascends towards the zenith, at which place it is nothing. 
 
 The adjoining cut will afford a sufficient illustration. 
 
 When the observer, standing upon the Earth at A, PARALLAX OF THE PLANKTS. 
 views the object at B, it appears to be at C, when, at 
 the same time, if viewed from the center of the Earth, 
 it would appear to be at D. The parallax is the angle 
 B C D or A B E, which is the difference between the 
 altitude of the object B, when seen from the Earth's 
 surface, and when seen from her center. It is also 
 the angle under which the semi-diameter of the Earth, 
 A E, is seen from the object B. 
 
 As the object advances from the horizon to the 
 zenith, the parallax is seen gradually to diminish, till 
 at F it has no parallax, or its apparent and true place 
 are the same. 
 
 This diagram will also show why objects nearest 
 the Earth have the greatest parallax, and those most 
 distant the least; why the Moon, the nearest of all 
 the heavenly bodies, has the greatest parallax ; while 
 the fixed stars, from their immense distance, have no 
 appreciable horizontal parallax the semi-diameter 
 of the Earth, at such a distance, being no more than a point. 
 
 660. As the effect of parallax on a heavenly body is to depress 
 it below its true place, it must necessarily affect its right ascen- 
 sion and declination, its latitude and longitude. On this account, 
 the parallax of the Sun and Moon must be added to their 
 apparent altitude, in order to obtain their true altitude. 
 
 The true altitude of the Sun and Moon, except when in the zenith, is always affected, 
 more or less, both by parallax and refraction, but always in a contrary manner. Hence 
 the mariner, in finding the latitude at sea, always adds the parallax, and subtracts the 
 refraction, to and from the Sun's observed altitude, in order to obtain the true altitude, 
 and thence the latitude. 
 
 661. The principles of parallax are of great importance to 
 astronomy, as they enable us to determine the distances of the 
 heavenly bodies from the Earth, the magnitudes of the planets 
 and the dimensions of their orbits. 
 
 The Sun's horizontal parallax being accurately known, the 
 Earth's distance from the Sun becomes known ; and the Earth's 
 distance from the Sun being known, that of all the planets may 
 be known also, because we know the exact periods of their 
 sidereal revolutions, and, according to the third law of Kepler, 
 the squares of the times of their revolutions are proportional to 
 the cubes of their mean distances. Hence, the first great 
 desideratum in astronomy, where measure and magnitude are 
 concerned, is the determination of the true parallax. 
 
 At a council of astronomers assembled in London some years since, from the m<vt 
 
 660. Effect of parallax ? How obtain true altitude ? How differ from refraction F 
 Dow then obtain true altitude ? 661. Use of parallax ? How employed ? Note ? 
 
306 
 
 ASTRONOMY. 
 
 learned nations in Enrope, the Sun's mean horizontal parallax was settled, as the n-*.i? 
 of their united observations, at 0* 0' 8".6776. Now the value of radius, expressed like- 
 wise in seconds, is 206264" .8; and this divided by 8".5776, gives 24047 for the distance of 
 the Sun from the the Earth, in semi-diameters of the latter. If we take the equatorial 
 semi-diameter of the Earth, as sanctioned by the same tribunal, at (7924+2=) 3962 tiiles, 
 we shall have 24047 x 3962= 95,273,869 miles for the Sun's true distance. 
 
 A TABLE OK THE SUN'S PARALLAX IN ALTITUDE. 
 
 Sun's 
 
 Aim. 
 
 Sun's Horizontal Parallax. 
 
 Sun's 
 Altit. 
 
 Sun's Horizontal Parallax. 
 
 
 8.4 
 
 8.5 
 
 8.6 
 
 8.7 
 
 8.8 
 
 
 8.4 
 
 8.5 
 
 8.6 
 
 8.7 
 
 8.8 
 
 
 
 8.40 
 
 8.50 
 
 8.60 
 
 8.70 
 
 8.80 
 
 45 
 
 5.94 
 
 6.01 
 
 6.08 
 
 6.15 
 
 6.22 
 
 5 
 
 8.87 
 
 8.47 
 
 8.57 
 
 8.67 
 
 8.77 
 
 50 
 
 5.40 
 
 5.46 
 
 5.53 
 
 5.59 
 
 5.66 
 
 10 
 
 8.27 
 
 8.37 
 
 8.47 
 
 8.57 
 
 8.67 
 
 55 
 
 4.82 
 
 4.88 
 
 4.93 
 
 4.99 
 
 5.05 
 
 15 
 
 8.11 
 
 8.21 
 
 8.31 
 
 8.40 
 
 8.50 
 
 60 
 
 4.20 
 
 4.25 
 
 4.30 
 
 4.35 
 
 4.40 
 
 20 
 
 7.89 
 
 7.99 
 
 8.08 
 
 8.18 
 
 8.27 
 
 65 
 
 8.55 
 
 8.59 
 
 3.63 
 
 8.68 
 
 3.72 
 
 25 
 
 7.61 
 
 7.70 
 
 7.79 
 
 7.88 
 
 7.98 
 
 70 
 
 2.87 
 
 2.91 
 
 2.94 
 
 2.98 
 
 3.01 
 
 30 
 
 7.28 
 
 7.36 
 
 7.45 
 
 7.53 
 
 7.62 
 
 75 
 
 2.17 
 
 2.20 
 
 2.23 
 
 2.25 
 
 2.28 
 
 35 
 
 6.88 
 
 6.96 
 
 7.04 
 
 7.13 
 
 7.21 
 
 80 
 
 1.46 
 
 1.48 
 
 1.49 
 
 1.51 
 
 1.53 
 
 40 
 
 6.44 
 
 6.51 
 
 6.59 
 
 6.66 
 
 6.74 
 
 85 
 
 0.73 
 
 0.74 
 
 0.75 
 
 0.76 
 
 0.77 
 
 45 
 
 5.94 
 
 6.01 
 
 6.08 
 
 6.15 
 
 6.22 
 
 90 
 
 0.00 
 
 0.00 
 
 0.00 
 
 0.00 
 
 0.00 
 
 662. The change in the apparent position of the fixed stars, 
 caused by the change of the Earth's place in her revolution 
 around the Sun, is called their annual parallax. So immense 
 is their distance, that the semi-annual variation of 190,000,000 
 of miles in the Earth's distance, from all those stars that lie in 
 the plane of her orbit, makes no perceptible difference in their 
 apparent magnitude or brightness. 
 
 The following cut will illustrate our meaning: 
 
 B 
 
 Let A represent a fixed star in the plane of the Earth's orbit, B. At C, the Earth is 
 190,000,000 of miles nearer the star than it will be at D six months afterward ; and yet 
 this serai-annual variation of 190,000,000 miles in the distance of the star is so small a 
 fraction of the whole distance to it, as neither to increase or diminish its apparent 
 brightness. 
 
 663. It is only those stars that are situated near the axis of 
 the Earth's orbit whose parallax can be measured at all, on 
 
 662. What meant by Earth's annual parallax f Effect of variation of Earth's d!s- 
 on the fixed stars? Diagram. 663. What stars have perceptible parallax 'i 
 
AURORA BOREALIS AND PARALT^X. 307 
 
 account of its almost imperceptible quantity. 
 So distant are they, that the variation of 
 190,000,000 miles in the Earth's place 
 causes an apparent change of less than 1' in 
 the nearest and most favorably situated 
 fixed star. 
 
 Let A represent the Earth on the 1st of January, and B a 
 star observed at that time. Of course, its apparent place in 
 the more distant heavens will be at C. But in six months the 
 Earth will be at D, and the star B will appear to be at E. 
 The angle A B D or B E will constitute the parallactic angle. 
 In the cut, this angle amounts to about 48, whereas the real 
 parallax of the stars is less than 1-th of one degree, or 
 "^ IMF o" tn P art ^ tnis amoun k Lines approaching each other 
 thus slowly would appear parallel ; and the Earth's crbit, if 
 filled with a globe of fire, and viewed from the fixed stars, 
 would appear but a point of light 1' in diameter ! For a 
 splendid diagram illustrative of the annual parallax of the stars, see Map I., of the Atlas. 
 
 ABERRATION OF LIGHT. 
 
 664. In the year 1725, Mr. Molyneux and Dr. Bradley fixed 
 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 190,000,000 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. 
 
 665. These observations were subsequently repeated, with but 
 little intermission, for twenty years, by the most acute observers 
 in Europe, and with telescopes varying from 12 feet to 36 feet 
 in length. In the mean time, Dr. Bradley had the honor of 
 announcing to the world the very nice discovery made while 
 endeavoring to ascertain the parallax of the fixed stars, that 
 the motion of light, combined with, tJie progressive motion of the 
 Earth in its orbit, causes the heavenly bodies to be seen in a differ- 
 ent position from what they would be, if the eye were at rest. Thus 
 was established the principle of the Aberration of Light. 
 
 666. This principle, or law, now that it is ascertained, seems 
 
 Amount? Diagram, and explanation. 664. What experiment by Molyneux ana 
 Bradley? With what results? 665. What further observations for the same purpose. V 
 What discovery made while investigating the subject of parallax ? What is the aberrn- 
 tlon of light ? 666 What remarks upon the principle or law of observation ? He w ia 
 
308 ASTRONOMY. 
 
 not only very plain, but self-evident. For if light be progres- 
 sive, 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. Hence the place 
 to which the telescope is directed will be different from the \rue 
 place of the object. 
 
 The quantity of this aberration is determined by a simple 
 proposition. 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 24 hours or 86400" : 493: :3548: 22"; which 
 is the change in the star's place, arising from the cause above- 
 mentioned. 
 
 CHAPTER XYIII. 
 
 PRACTICAL ASTRONOMY REFLECTION AND REFRAC- 
 TION OF LIGHT. 
 
 667. Practical Astronomy has respect to the means employed 
 for the acquisition of astronomical knowledge. It includes the 
 properties of light, the structure and use of instruments, and 
 the processes of mathematical calculation. 
 
 In the present treatise, nothing further will be attempted than a mere introduction tc 
 practical astronomy. In a work designed for popular use, mathematical demonstrations 
 would be out of place. Still, e very student in astronomy should know how telescopes are 
 made, upon what laws they depend for their power, and how they are used. It is for thid 
 purpose mainly that we add the following chapters on practical astronomy. 
 
 PROPERTIES OF LIGHT. 
 
 668. Light is that invisible ethereal substance by which we 
 are apprised of the existence, forms, and colors of material 
 objects, through the medium of the visual organs. To this sub- 
 tile fluid we are especially indebted for our knowledge of those 
 distant worlds that are the principal subjects of astronomical 
 inquiry. 
 
 669. The term light is used in two different senses. It may 
 signify either light itself, or the degree of light by which we are 
 enabled to see objects distinctly. In this last sense, we put light 
 
 the quantity of aberration determined ? 667. Subject of Chapter XVIII. ? What is 
 practical astronomy t How far discussed in this treatise? 668. Define light. For 
 what indebted to it? 669. Different senses in which the term is used? What b 
 
REFLECTION AND REFRACTION OF LIGHT. 30l> 
 
 in opposition to darkness. But it should be borne in mind, that 
 darkness is merely the absence of that degree of light which is 
 necessary to human vision ; and when it is dark to us, it may be 
 light to many of the lower animals. Indeed, there is more or 
 less light, even in the darkest night, and in the deepest dungeon. 
 
 " Those unfortunate individuals," says Dr. Dick, " who have been confined in the dark- 
 est dungeons, have declared, that though, on their first entrance, no object could be per- 
 ceived, perhaps for a day or two, yet, in the course of time, as the pupils of their eyes 
 expanued, they could readily perceive rats, mice, and other animals that infested their 
 cells, and likewise the walls of their apartments ; which shows that, even in such situa- 
 tions, light is present, and produces a certain degree of influence." 
 
 670. Of the nature of the substance we call light, two theo 
 ries have been advanced. The first is, that the whole sphere of 
 the universe is filled with a subtile fluid, which receives from 
 luminous bodies an agitation ; so that, by its continued vibra- 
 tory motion, we are enabled to perceive luminous bodies. This 
 was the opinion of Descartes, Euler, Huygens, and Franklin. 
 
 The second theory is, that light consists of particles thrown 
 off from luminous bodies, and actually proceeding through space. 
 This is the doctrine of Newton, and of the British philosophers 
 generally. 
 
 Without attempting to decide, in this place, upon the relative merits of these two hypo- 
 theses, we shall use those terms, for convenience sake, that indicate the actual passage 
 of light from one body to another. 
 
 671. Light proceeds from luminous bodies in straight lines, 
 and in all directions. It will not wind its way through a crooked 
 passage, like sound ; neither is it confined to a part of the cir- 
 cumference around it. 
 
 As the Sun may be seen from every point in the solar system, and far hence into space 
 'n every direction, even till he appears but a faint and glimmering star, it is evident that 
 he fills every part of this vast space with his beams. And the same might be said of 
 every star in the firmament. 
 
 672. As vision depends not upon the existence of light merely, 
 but requires a certain degree of light to emanate from the object, 
 and to enter the pupil of the eye, it is obvious that if we can, 
 by any means, concentrate the light, so that more may enter the 
 eye, it will improve our perception of visible objects, and even 
 enable us to see objects otherwise wholly invisible. 
 
 Some animals have the power of adapting their eyes to the existing degree of lighC 
 The cat, horse, &c., can see day or night; while the owl, that sees well in the night, sees 
 poorly in the day-time. 
 
 673. Light may be turned out of its course either by reflection 
 
 darkless ? Can it be dark and light at the same time ? Is there any place without 
 light? Quotation from Dr. Dick? 670. What theories of the nature of light, and by 
 Whom supported respectively? Remark of author? 671. How light proceeds from 
 'uminous bodies ? Radiations from Sun and stars ? 672. How improve vision, and 
 Vhy ? Animals ? 673. How is light turned out of its course ? 
 
310 
 
 ASTRONOMY. 
 
 or refraction. It is reflected when it falls upon the highly polished 
 surface of metals and other intranspareiit substances ; and 
 refracted when it passes through transparent substances of diffe- 
 rent densities, as already illustrated in Chapter XYI. 
 
 REFRACTION BY GLASS LENSES. 
 
 674. A lens is a piece of glass, or other transparent substance, 
 of such a form as to collect or disperse the rays of light that 
 are passed through it, by refracting them out of a direct course. 
 They are of different forms, and have different powers. 
 
 In the adjoining cut, we have an edgewise 
 view of six different lenses. 
 
 A is the plano-convex, or half a double con- 
 vex lens ; one side being convex and the other 
 plane. 
 
 B is a plano-concave ; one surface being con- 
 cave, and the other plane. 
 
 C is a double-convex lens, or one that is 
 bounded by two convex surfaces. 
 
 I) is a double-concave lens, or a circular piece 
 of glass hollowed out on both sides. 
 
 E is a concavo-convex lens, whose curves 
 differ, but do not meet, if produced. 
 
 P is a meniscus, or a concavo-convex lens, 
 the curves of whose surfaces meet. 
 
 LENSES OF DIFFERENT FORKS. 
 
 675. A double-convex lens 
 converges parallel rays to a 
 point called the focus ; and 
 the distance of the focus 
 depends upon the degree of 
 cocvexity. 
 
 In the first of these cuts, the lens is 
 quite thick, and the focus of the rays is 
 quite near ; but the other being less 
 convex, the focus is more distant. 
 
 676. The distance of the 
 focus of a double-convex glass 
 lens is the radius of the sphere 
 of its convexity. 
 
 In this cut, it will be seen that the 
 parallel rays A are refracted to a focus 
 at C, by the double-convex lens B, the 
 convexity of whose surfaces is just equal 
 to the curve of the circle D. 
 
 677. The focal distance of 
 a plano-convex lens is equal to 
 the diameter of the sphere 
 
 formed by the convex surface produced. 
 
 LIGHT REFRACTED BY LENSES. 
 
 DOUBLE CONVEX FOCAL DISTANCE. 
 
 6T4. What is a lens ? Draw and describe different kinds. 675. Refracting power of 
 double-convex lens? Focal distance? Diagram, and illustrate. 6T6. Hew focal dis- 
 tance governed ? Diagram, and illustrate. 677. What is the focal distance of a 
 
REFLECTION AND REFRACTION OF LIGHT. 
 
 311 
 
 It must be borne in mind, that PLANO-CONCAVB FOCAL DISTANCT. 
 
 light is refracted both when it 
 enters, and when it lea res a double 
 convex lens, and in both instances 
 in the same direction ; and, so far 
 as the distance of the focus is 
 concerned, to the same extent. 
 But when the lens is convex only 
 on one side, half its refracting 
 power is gone, so that the rays 
 are not so soon refracted to a 
 focus. In this case, the focal dis- 
 tance is equal to the diameter of 
 the sphere formed by extending 
 the convex surface of the lens; 
 while with the double-convex lens, 
 the focal distance is only equal to 
 the radius of such sphere. In the cut, the parallel rays A ure refracted to a focus at 
 B, by the plano-concave lens C ; and the distance C B is the diameter of the circle 
 D, formed by the convex surface of the lens C produced. 
 
 678. A double-cm- 
 cave lens disperses pa- 
 rallel rays, as if they 
 diverged from the cen- 
 ter of a circle formed 
 by the convex surface 
 produced. 
 
 In this cut, the parallel rays 
 A are dispersed by the double- 
 concave lens C, as shown at 
 B; and their direction, as 
 thus refracted, is the same 
 as if they proceeded from the point D, which is the center of a circle formed by the 
 concave surface of the lens produced. 
 
 679. Common spectacles, opera-glasses, burning-glasses, and 
 refracting telescopes are made by converging light to a focus, by 
 the use of double-convex lenses. 
 
 RAYS DISPERSED BV REFRACTION. 
 
 \ 
 
 BCRNINQ-GLASS. 
 
 The ordinary burning-glass, which may be 
 bought for a few shillings, is a double-convex 
 disk of glass two or three inches in diameter, 
 inclosed in a slight metallic frame, with a han- 
 dle on one side. Old tobacco-smokers some- 
 times carry them in their pockets, to light their 
 pipes with when the Sun shines. In other in- 
 stances, they have been so placed, as to fire a 
 cannon in clear weather, by igniting the prim- 
 ing at 12 o'clock. 
 
 The adjoining cut represents a large burn- 
 ing-glass converging the rays of the Sun to a 
 focus, and setting combustible substances on 
 fire. Such glasses have been made powerful 
 enough to melt the most refractory substances, 
 as platinum, agate, &c. " A lens three feet in 
 diameter," says Professor Gray, " has been 
 known to melt cornelian in 75 seconds, and a 
 piece of white agate in 30 seconds." 
 
 plano-convex lens ? Diagram. 6T8. Effect of double-conv&c lens? Amount of diver 
 poncy of rays? 679. What articles made with double-convex lenses ? Uses? Powe 
 of burning glasses? 
 
312 
 
 ASTRONOMY 
 
 REFLECTION OF LIGHT. 
 
 680. We have now shown how light may be turned out of its 
 courso, and analyzed, dispersed, or converged to a point by 
 refraction. Let us now consider how it may be converged to a 
 focus by reflection. 
 
 When light falls upon a highly-polished surface, especially of 
 metals, it is reflected or thrown off in 
 a new direction, and the angles of 
 contact and departure are always 
 equal. 
 
 Let A B represent the -polished metallic surface, 
 C the source of light, and the arrows the direction 
 of the ray. Then D would represent the angle of 
 incidence or contact, and E the angle of reflection 
 or departure which angles are seen to be equal. A. 
 
 REFEECTION BY A PLANJQ 1IIUK011. 
 
 REFLECTION BY A CONCAVE MIRROR. 
 
 681. A concave mirror re- 
 flects parallel rays back to a 
 focus, the distance of which 
 is equal to half the radius of 
 the sphere formed by the 
 concave surface produced. 
 
 In this cut, the parallel rays A fail 
 upon the concave mirror B B, and are 
 reflected to the focus C, which is half 
 the radius of the sphere formed by the 
 surface of the mirror produced. If, 
 therefore, it was desirable to construct 
 a concave mirror, having its focus 10 
 feet distant, it would only be necessary 
 to grind it on the circle of a sphere 
 having a radius of 20 feet. 
 
 682. In reflection, a por- 
 tion of the light is absorbed 
 or otherwise lost, so that a 
 reflector of a given diameter 
 
 will not converge as much light to a focus as a double-convex 
 lens of the same size. In the latter case all the light is trans- 
 mitted. Still, reflectors have been found of such power as to 
 melt iron, and other more difficult substances. 
 
 We have now considered so much of optics as is necessary to an understanding of the 
 principles upon which telescopes are constructed; and, for further particulars, shaU 
 refer the student to books on Natural Philosophy. 
 
 6SO. What now shown in this chapter? What next? What is reflect ion, and when 
 1oes it take place? What law governs it? Diagram. 681. How does a concave: 
 mirror reflect parallel rays 1 Distance of focus ? Diagram. How would you construct 
 a concave mirror with a 10 feet focus ? 6S2. Is all the light falling upon a polished 
 surface reflected ? What then ? Closing note ? 
 
TELESCOPES REFKACTORS AND REFLECTORS. 318 
 
 / '. / '". * .,.,.:.,,,-.-_ , 
 
 CHAPTER XIX. 
 TELESCOPES KEFKACTORS AND REFLECTORS. 
 
 683. A TELESCOPE is an optical instrument employed in view- 
 ing distant objects, especially the heavenly bodies. The term 
 telescope is derived from two Greek words, viz., tele, at a distance, 
 and tkopeo, to see. So far as is now known, the ancients had no 
 knowledge of the telescope. Its invention, which occurred in 
 1609, is usually attributed to Galileo, a philosopher of Florence, 
 in Italy. 
 
 The discovery of the principle upon which the refracting telescope is constructed waa 
 purely accidental. The children of one Jnnfsen, a spectacle-maker of Middleburgh, in 
 Holland, being at play in their father's shop, happened to place two glasses in such a 
 manner, that in looking through them, at the weathercock of the church, it appeared to 
 be nearer, and much larger than usual. This led their father to fix the glasses upon a 
 board, that they might be ready for observation ; and the news of the discovery was soon 
 conveyed to the learned throughout Europe. Galileo hearing of the phenomenon, sooc 
 discovered the secret, and put the glasses in a tube, instead of on a board ; and thus the 
 first telescope was constructed. 
 
 684. The telescope of Galileo was but one inch in diameter, 
 and magnified objects but 30 times. Yet with this simple 
 instrument he discovered the face of the Moon to be full of ine- 
 qualities, like mountains and valleys ; the spots on the Sun ; tho 
 phases of Yenus ; the satellites of Jupiter ; and thousands of 
 new stars in all parts of the heavens. 
 
 Notwithstanding this propitious commencement, so slow was the progress of the 
 telescope towards its present state, that in 1816, Bonnycastle speaks of the 30- fold mag- 
 nifying power of the telescope of Galileo as " nearly the greatest perfection that thia 
 Kind of telescope is capable of 1" 
 
 685. If he be the real author of an invention who, from a 
 knowledge of the cause upon which it depends, deduces it from 
 one principle to another, till he arrives at the end proposed, 
 then the whole merit of the invention of the telescope belongs to 
 Galileo. The telescope of Jansen was a rude instrument of mere 
 curiosity, accidentally arranged ; but Galileo was the first who 
 constructed it upon principles of science, and showed the practi- 
 cal uses to which it might be applied. 
 
 It is said that the original telescope constructed by Galileo is still preserved in the 
 British Museum. A pigmy, indeed, in its way, but the honored progenitor of a race of 
 giants ! 
 
 686. The discovery of the telescope tended greatly to sustain 
 
 683. Subject of Chapter XIX. ? Telescope ? Derivation ? Ancient or modern ? In- 
 ventor? Incidents of discovery? 684. Galileo's telescope? Discoveries with it? 
 Progress Sn telescope making? 686. Is Galileo entitled to the honor of inventing the 
 tclcoco^e ? Where is his? 686. Relation of discovery to Coperuican theory? Meets 
 
3 it ASTRONOMY. 
 
 the Copernican theory, which had just been promulgated, and of 
 which Galileo was an ardent disciple. Like Copernicus, how 
 ever, his doctrines subjected him to severe persecutions, and he 
 was obliged to renounce them. 
 
 The following is his renunciation, made June 28,1638: " I, Galileo, in the seventieth 
 year of my age, on bended knees before your eminences, having before my eyes and 
 touching with my hands the Holy Gospels, I curse and detest the error of the Earth's 
 movement." As he left the court, however, after this forced renunciation, he is said to 
 have stamped upon the Earth, and exclaimed, " It does move, after all?" Ten years 
 after this, he was sent to prison for the same supposed error ; and soon, his age advanc- 
 ing, the grave received him from the malice of his persecutors. 
 
 DIFFERENT KINDS OF TELESCOPES. 
 
 687. Telescopes are of two kinds Reflectors and Refractors. 
 Refracting telescopes are made by refracting the light to a focus 
 with a glass lens (675) ; and reflecting telescopes, by reflecting 
 it to a focus with a concave mirror (681). Besides this 
 general division, there are various kinds both of reflectors and 
 refractors. 
 
 Telescopes assist -vision in various ways first, by enlarging the visual angle under 
 which a distant object is seen, and thus magnifying that object ; and, secondly, by 
 converging to a point more light than could otherwise enter the eye thus rendering 
 objects distinct or visible that would otherwise be indistinct or invisible. 
 
 All the light falling upon a six or a twelve inch lens may be converged to a focus, so 
 as to be taken into the human eye through the pupil, which is but one-fourth of an inch 
 in diameter. Our vision is thus made as perfect bj art as if nature had given us ability 
 to enlarge the eye till the pupil was a foot in diameter. 
 
 688. Refracting telescopes may consist of a double-convex 
 lens placed upon a stand, without tube or eye-piece. Indeed, a 
 pair of ordinary spectacles is nothing less than a pair of small 
 telescopes, for aiding impaired vision. 
 
 REFRACTING TELESCOPE WITH A SINGLE LENS. 
 
 Here the parallel rays are seen to pass through the lens at A, and to be so converged 
 to a point as to enter the eye of the beholder at B. His eye is thus virtually enlarged to 
 the size of the lens at A. But it would be very difficult to direct such a telescope toward 
 celestial objects, or to get the eye 5n the focus after it was thus directed. 
 
 upon Galileo? His renunciation? Death? 687. Kinds of telescopes? Dcccrib-i. 
 Uow assist vision? Illustration. 688. Simplest form of refracting telescope V 
 
TELESCOPES REFRACTORS AND REFLECTORS. 315 
 
 689. The Galilean telescope consists of two glasses a double- 
 convex next the object, and a double-concave near the eye. The 
 former converges the light till it can be received by a small 
 double-concave, by which the convergency is corrected (502), 
 and the rays rendered parallel again, though in so small a beam 
 as to be capable of entering the eye. 
 
 GALILEAN THLE800PB. 
 
 Here the light is converged by the lens A, till it can be received by the double-concave 
 lens B, by which the rays are made to become a small parallel beam that can enter the 
 eye at C. This was the form of the telescope constructed by Jansen, and improved by 
 Galileo ; on which account it is called the Galilean telescope. In the cut, the two lenses 
 are represented as fastened to a board, as first exhibited by Jansen. 
 
 690. The common astronomical telescope consists of two 
 glasses viz., a large double-convex lens next the object, called 
 the object-glass ; and a small double-convex lens or microscope 
 next the eye, called the eye-piece. For the greater convenience in 
 using, they are both placed in a tube of wood or metal, and 
 mounted in various ways, according to their size, and the pur- 
 poses to which they are devoted. 
 
 PLACED IN A TUBB. 
 
 A is the object-glass, B the eye-piece, and C the place where the tube, in which the eye- 
 piece is set, slides in and out of the large tube, to adjust the eye-piece to the focal dis- 
 tance. By placing the lenses in a tube, the eye is easily placed in the focus, and the 
 object-glass directed toward any desired object. 
 
 691. The object-glass of a telescope is usually protected, when 
 not in use, by a brass cap that shuts over the end of the instru- 
 ment ; and the eye-pieces, of which there are several, of differ- 
 
 689. Galilean telescope? Why called Galilean? 690. How common astronomical 
 tele-scopes made? Why in tube? 69 1. How object-glass protected? Wlvit ssU >f 
 eye- pieced ? 
 
 B.G. 
 
 14 
 
316 
 
 ASTRONOMY 
 
 REFRACTING TELESCOPE MOUKTBD O2f A 3WJ2X 
 
 ent magnifying powers, 
 are so fixed as to screw 
 into a small movable tube 
 ID the lower end of the 
 instrument, so as to adjust 
 them respectively, to the 
 focus, and to the eyes of 
 different observers. Such 
 telescopes usually repre- 
 sent objects in an invert- 
 ed position. 
 
 The adjoining cut represents the 
 simplest form of a mounted refrac- 
 tor. The object-glass is at A, where 
 the -brass cap may be seen cover- 
 ing it B is the small tube into 
 which the eye-piece is screwed, and 
 which is moved in and out by the 
 email screw C. Two eye-pieces 
 may be seen at D one short one, 
 for astronomical observations, and 
 a long one, for land objects. For 
 viewing the Sun, it is necessary to 
 add a screen, made of colored 
 glass. At E, a bolt goes into a 
 socket in the top of the stand, in 
 which it turns, allowing the tele- 
 scope to sweep around the horizon ; while the joint, connecting the saddle in which tii* 
 telescope rests with the top of the bolt, allows it to be directed to any point between the 
 horizon and the zenith. But such stands answer only for comparatively small instruments. 
 
 692. Refracting telescopes are mounted in various ways. 
 So important is it that they should not shake or vibrate, that, in 
 most observatories, the stand rests upon heavy mason-work in 
 no way connected with the building, so that neither the wind 
 nor the tread of the observer can shake it. They are then fur- 
 nished with a double axis, which allows of motion up and down, 
 or east and west ; and two graduated circles show the precise 
 amount of declination and right ascension. 
 
 They are often furnished with clockwork, by which the telescope Is made to move 
 westward just as fust -as the Earth turns eastward; so that the celestial object being 
 once found, by setting the instrument for its right ascension and decimation, or by the 
 aid of the Finder a small telescope attached to the lower end of the large one it may 
 be kept in view by the clockwork for any desirable length of time. A telescope thus fur- 
 nished with right ascension and declination circles is called an Equatorial, or is said to 
 be equatoriall/y mounted, because it sweeps east and west in the heavens parallel to the 
 equator. 
 
 693. The object-glasses of telescopes are not always made of 
 a single piece of glass. They may be made of two concavo-con- 
 vex glasses, like two watch crystals, with their concave sides 
 
 692. How refractors mounted, and why? When equatorial, and why? 698. Ilov 
 Object-glasses made? What a leruif A Barlow lens? 
 
TELESCOPES REFRACTORS AND REFLECTORS. 317 
 
 towards each other, or with a thin double concave glass between 
 -them. They are thus double, or triple ; but when thus con- 
 structed, the whole is called a lens, as if composed of a single 
 piece. 
 
 Lenses have also been formed by putting two concavo-conveT glasses together, and 
 filling the space between them with some transparent fluid. These are called Barlow 
 lenses, from Prof. Barlow, their inventor. 
 
 694. As a prism analyzes the light, and exhibits different 
 colors, so a double convex lens may analyze the light that falls 
 near its circumference, and thus represent the outside of the 
 heavenly bodies as colored. But this defect is remedied by 
 using discs made of different kinds of glass, so as to correct one 
 refraction by another. Refracting telescopes thus corrected are 
 called Achromatic telescopes. 
 
 Achromatic is from the Greek a chroma, which signifies destitute of color. Most 
 refracting telescopes are now so constructed as to be achromatic. 
 
 695. It is but recently that any good refracting telescopes 
 have been made in this country. The best have formerly been 
 made in Germany and France ; but a number of very fine instru- 
 ments have been made in this country, most of them by Mr. 
 Henry Fitz, Jun., formerly of New York City. Several very 
 good instruments have also been" made by Alvan Clark, Esq., of 
 Boston, and others still by Charles A. Spencer, Esq., of Troy, 
 N. Y. Mr. Fitz died in New York, November 27, 1863. 
 
 1. The author was personally well acquainted with Mr. Fitz, and during his life gave 
 favorable descriptions of his instruments in these pages, and did all that he could to 
 make his capabilities known to the American public. He made his first telescope in 
 1835. In the Winter ot 1844 he invented a method of perfecting object-glasses for refract- 
 ing telescopes, making the first one of the bottom of an ordinary tumblor. In the Fall 
 of 1845 he exhibited, at the Fair of the American Institute, an instrument of 6 inches 
 aperture, which, although made of common American material, in the way of flint glass, 
 was a very excellent instrument Continually progressing in size, he finally succeeded in 
 making instruments of 16 inches aperture, one of which is now in the possession of Mr. 
 Van Duzee, of Buffalo, N. Y. He made two of 13 inches one for the Dudley Observa- 
 tory, at Albany, and the other for an association of gentlemen, at Alleghany City, Pa. 
 Of 12 inches aperture, he produced one for the Observatory at Ann Arbor, Michigan, and 
 another for the Vassar Female College. He made for M. L. Rutherford, of New York. 
 at various times, telescopes of 4, 5J, 6," 9, and 11 J inches aperture ; the last, an instrument 
 of remarkable defining power, is now mounted in Mr. Rutherford's Observatory, in 
 Eleventh Street, New York City. Mr. Vickers, of Baltimore, has a 10-inch. Several 
 of the size of 8 and 9 inches are scattered over the country. The British Charg6 d 1 Af- 
 faires at Montevideo has a 9-inch. Mr. Campbell, of New York, has an 8-inch. Of a 
 large number of 6 inches aperture, one very fine instrument was ordered by the United 
 States Government, for Lieut. Gillies's expedition to Chili ; it is still in the Observatory 
 of the Chilian Government At about the same time, he made another of the same size 
 for Mr. Robert Van Arsdale, of Newark. N. J. Mr. Thomas F. Harrison, Principal of the 
 Public Grammar School in Greenwich Avenue, New York, has another mounted on that 
 building. 
 
 2. For a list of telescopes in this country, with the names of their respective makers, 
 focal length, size of object-glasses, &c., see table on subsequent page. 
 
 695. What said of the manufacture of telescopes.? What other Americans have miido 
 them ? (What said of Mr. Fitz ? Telescopes ?) 
 
318 
 
 ASTRONOMY. 
 
 RUTHKEFOED'S EQUATORIAL EEFBACTOU. 
 
 696. The above cut represents an equatorial telescope manu- 
 factured by Mr. Henry Fitz, of New York the one used by 
 the author in making most of his observations. Its object- 
 glass is six inches in diameter, and its focal length eight feet. 
 It is perfectly achromatic, and performs all the tests laid down 
 in Dick's Practical Astronomer, as evidence of a good instru- 
 ment, with perfect ease. Under favorable circumstances, it 
 shows the sixth star in the trapezium of Orion, and to show 
 Polaris double is a very easy test indeed. 
 
 A Finder is seen attached to the lower end of the large instrument It takes in a 
 larger field of view in the heavens than the latter, and enables the observer to look uu 
 objects with facility, and bring them into the field of the larger instrument. 
 
REFRACTING TELESCOPES. 
 
 319 
 
 
 THB PHILADELPHIA REFRACTOR.* 
 
 697. This instrument is located in the Observatory of the High- 
 School of Philadelphia. Its focal length is eight feet, and its 
 aperture six inches the same as the one on the preceding page. 
 It was made by Merz & Mahler, of Munich, and cost $2,200. 
 
 * We are indebted to the courtesy of Messrs. Harper Brothers, of New York, fo- 
 copies of several of these cuts from their Monthly Magazine for June, 1856. 
 
 C97 The Philadelphia refractor? Size? By whom made? Cost? 
 
320 
 
 ASTROXOMY. 
 
 HAMILTON COLLEGE E.WBACTOK. 
 
 .21.11 
 
 698. This instrument has a focal length of sixteen feet, with 
 an object-glass thirteen-and-a-half inches in diameter. Its focal 
 length is therefore about four feet less than is usaal in the Mu- 
 nich instruments of the same aperture. The flint and crown 
 glass discs for it were imported from Germany, and the instru- 
 ment was made by Messrs. Spencer & Eaton, of Canastota, N. Y., 
 at a cost of $10,000. It is reported to be a very superior tele- 
 scope, and, in workmanship, is regarded as fully equal to the 
 Munich instruments. 
 
 698. Size of the Hamilton College telescope? 
 whom made? Cost? 
 
 What peculiarity as to length? By 
 
REFRACTING TELESCOPES 
 
 321 
 
 GREAT REFRACTING TBLE8COPE AT CINCINNATI, OHIO. 
 
 699. The above cut represents one of the best telescopes in 
 the United States. It is located in the observatory on Mount 
 Adams, near Cincinnati, Ohio, and was for several years under 
 the direction of the late Prof. O. M. Mitchel, by whose instru- 
 mentality it was purchased and mounted. 
 
 The object-glass is about 12 inches in diameter, with a focal distance of 17 feet li 
 was purchased in Munich, Germany, in 1844, at an expense of nearly ten thousand 
 dollars. 
 
 699. Cincinnati refractor where located? By whom purchased ? (Where? When? 
 Cost ? Size and focal distance ?) 
 
322 
 
 ASTRONOMY. 
 
 THB BQUATOBIAL BEFBACTOE AT ALBANY, N. T. 
 
 TOO. This superb instrument is mounted in the Dudley Ob- 
 servatory, at Albany, and is one of the most important instru- 
 ments in America. Its focal length is 15 feet 2 inches. The 
 object-glass, made by the late Henry Fitz, of New York, is 13 
 inches clear aperture, and the tube is of mahogany, constructed 
 by glueing together strips of about an inch in width. A finder, 
 or small telescope for finding objects, is seen attached to the 
 lower end of the large instrument. 
 
 700. Where located? Size? Bj -whom made ? What said of tube? Finder t 
 
REFRACTING TELESCOPES. 
 
 323 
 
 THE GREAT EQUATORIAL REFRACTOR AT CAMBRIDGE MASS. 
 
 701. This is probably the best ins mment in the United State*. 
 Its object-glass is 15 inches in diameter, with a focal length of 
 22 feet 6 incnes. It has eighteen different powers, ranging from 
 103 to 2,000. It was made by Merz & Mahler, of Munich, Ba- 
 varia, and cost $19,842. 
 
 The cut shows the opening in the revolving dome of the observatory, and the observer 
 In his chair at the eye-piece. 
 
 701. Comparative value? Siz? Magnifying powers? By whom made? (Jest of 
 Instrument? 
 
321 
 
 ASTRONOMI', 
 
 THB OBEA1 CKAI& TbLESCOPE, WAND8WOKTU COMMON, NKAE LONDON. 
 
 702. This is the largest refracting telescope ever constructed 
 The object-glass is two feet in diameter, with a focal distance of 
 76 feet. The tube is of heavy sheet iron, and shaped somewhat 
 like a cigar. It is 13 feet in circumference in the largest pla^e, 
 and weighs about three tons. 
 
 This.telescope is suspended from a brick tower, 65 feet high, 15 feet in diameter, and 
 weighing 220 tons. The top of the tower, from which the telescope is suspended, re- 
 volves ; and by a chain running over pulleys, and a weight and windlass, it is balanced, 
 and raised or lowered. The lower end rests on a small carriage, that runs upon a circi.- 
 lar railroad around the tower, at the distance of 52 feet from its center. By these means 
 it is directed to almost any point in the heavens. It is called the " Craig" telescope, in 
 honor of the Rev. Mr. Craig, under whose direction, and at whose expense, it was con- 
 ttructed. It is located at Wandsworth Common, near London. 
 
 71/2. Describe the Craig telescope. Object glass ? Focal distance ? 
 mounted? Why ailed " f>aig" telescope f Where located ? 
 
 T be ? How 
 
TRANSIT INSTRUMENTS. 325 
 
 A TRANSIT IJV8TKTTMENT. 
 
 703. A Transit Instrument is a telescope used for observing 
 the transits of celestial objects across the meridian, for the pur- 
 pose of determining differences of right ascension, or obtaining 
 correct time. They are usually from six to ten feet long, and 
 are mounted upon a horizontal axis, between two abutments of 
 mason-work ; so that the instrument, when horizontal, will point 
 exactly to the south. It will then take objects in the heavens, 
 when they are exactly on the meridian. 
 
 The Transit Instrument and Mural Circle have been combined 
 in one instrument, called a Meridian Circle, as shown on a sub- 
 sequent page. 
 
 Let A D in the cut represent the telescope, and E and W the east and west abutments, 
 between which it is placed. On the left is seen, attached to the mason work, a graduated 
 circle; and on the eastern end of the axis of the telescope is seen an arm, TJ, extending 
 to the circle, as an index. Now, suppose the index n to be at 0, in the upper part of the 
 circle, when the telescope is horizontal ; then if the meridian altitude of the object to bo 
 taken is 10% the index must be moved 10 from 0, as the degrees on the circle and the 
 altitude of the object will correspond. 
 
 703. What is a transit instrument? Size? How mounted? Describe parts as shown 
 in the cut. llow set the instrument for the altitude of a star? What combination 
 nj>oken off 
 
326 
 
 ASTRONOMY. 
 
 TRANSIT INSTRUMENT, WASHINGTON, D. C. 
 
 704. This instrument is located in the National Observatory, 
 at Washington, D. C. It is mounted upon piers of granite, which 
 rest firmly upon a foundation of stone, extending ten feet below 
 the surface of the ground. The object-glass was furnished by 
 Merz & Mahler, and the instrument was constructed by Ertel & 
 Son, Munich. The entire cost was $1,480. 
 
 704. Whore located? How mounted ? By whom mad?? Gout? 
 
TRANSIT INSTRUMENTS. 
 
 327 
 
 KBRTDTAN CIRCLE AT ALBANY, JT. T. 
 
 705. This is a superior transit instrument, with a mural circle 
 attached. It is located in the east wing of the Dudley Observa- 
 tory, at Albany, N. Y., and rests upon piers of Lockport lime- 
 stone, which rest upon a bed of sand and gravel, some ten feet 
 below the floor of the cellar. Taken as a whole, it is probably 
 the best transit instrument in the United States. 
 
 1. A Mural Circle is a large graduated circle, with a telescope crossing its center, used 
 for the measurement of the altitudes and zenith distances of the heavenly bodies, at the 
 instant of their crossing the meridian. They are usually fixed upon a horizontal axis, 
 that turns in a socket firmly fixed in a north Aid south wall. The degrees, minutes, 
 and seconds on the circle are read by means of microscopes, and indicate the altitude 
 of the object. The Mural Circle and a transit instrument, as now combined, are called 
 a Meridian Circle. 
 
 T05. Where located? How mounted? Comparative importance? What is a Mitral 
 ? How combined? What called ? 
 
 Circle t Use? How usualh mounted 
 
328 ASTRONOMY. 
 
 2. The old Mural Circle is now being rapidly superseded by the Meridian Circle in 
 the best observatories. 
 
 706. A Comet Seeker is a re- A COMET SEEKER. 
 fracting telescope with a large 
 
 aperture and short focal distance. 
 As comets cannot be found by 
 their right ascension and declina- 
 tion, but often have to be 
 searched up, by sweeping around 
 the heavens with a telescope, be- 
 fore they became visible to the 
 naked eye, it is important to 
 have telescopes that will cover 
 considerable space that is, of 
 wide aperture and short focal distance. Such a telescope was 
 made by Mr. Fitz for Miss Mitchel, of Newport, R. I. 
 
 Miss Mitchel is an amateur astronomer, and has the honor of having discovered a num- 
 ber of new comets. 
 
 707. An Astronomical Clock is a clock adapted to keep exact 
 sidereal time. Taking the vernal equinox in the heavens as the 
 zero point, and reckoning 24 hours eastward to the same point 
 again, the time reckoning 15 to an hour when an object 
 crosses the meridian, will always represent the right ascension 
 of the object. Hence right ascension is usually given in hours, 
 minutes, and seconds ; or in time by the astronomical clock, set 
 by the vernal equinox. 
 
 Professor Mitchel, we believe, made some valuable improvements in astrononrcal 
 clocks. A very fine instrument of this kind is located in the Dudley Observatory, at 
 Albany, N. Y. 
 
 REFLECTING TELESCOPES. 
 
 708. The Reflecting Telescope is one in which the light is con- 
 verged to a focus by means of a concave metallic reflector or 
 speculum. Like the Refractors, they may be constructed with 
 very little mounting ; though for convenience in use, it is neces- 
 bary to place the reflector in a tube. 
 
 The student should fully understand the difference between the two kinds of tele- 
 boopes, viz. : refractorx and reflectors. In one respect they are alike, as they both con- 
 wrge the rays of light to a focus; but they do it by widely different processes, as the 
 following pages will show. 
 
 706. What is a comet seeker? Why necessary? 707. What is an astronomical 
 clock ? 70S. Describe a reflecting telescope. Simplest form ? 
 
DIFFERENT KINDS OF TELESCOPES. 
 
 SIMPLEST FORM OF A REFLECTING T2L23COPK. 
 
 329 
 
 In this cut, the light A is seen passing from the object on the right, and falling upon 
 the concave surface of the reflector at B, from which it is reflected back to a focus, and 
 enters the eye -of the observer at 0. This telescope has no eye-piece. 
 
 708. The focal distance of a concave reflector is equal to half 
 the radius of the sphere formed by the concave surface pro- 
 duced. Hence to grind a reflector for a focus of 20 feet, it will 
 be necessary to have the curve that of a circle whose radius is 
 40 feet. 
 
 FOCAL DISTANCE OF A CONCAVE nKFLBCTOR. 
 
 Here the curve of the speculum B is that of a circle, whose center 
 is ; while the focus of the speculum is at D, which is only half 
 the distance from B to C. 
 
 709. Reflecting telescopes are of several kinds viz., the Gre- 
 rwM, the Newtonian, the Casscgranian, the Herschdian, &c. 
 The Gregorian Rejkdor has an aperture in the center of the 
 speculum, and a small concave mirror in the focus of the specu- 
 uin, which reflects the light back through the aperture to the 
 eye-piece. In this way the observer is enabled to face the 
 object, and to direct the telescope toward it, as if it were a 
 refractor. 
 
 708. Focaj distance? 709. How many kinds of reflectors? Describe the Gregorian. 
 Why colled Gregorian? 
 
330 
 
 ASTRONOMY. 
 
 QkKGOKlAN I'.EKLKCTOR. 
 
 Here the light A falls upon the speculum at B, and is reflected back to the small mir- 
 ror C, by which it is thrown out through the aperture in the speculum, to the eje of tho 
 observer at D. The object is supposed to be off on the right, in the direction towards 
 which the instrument is pointed. It is called a Gregorian telescope, after Mr. Jamea 
 Gregory, who first suggested the construction of reflecting telescopes. 
 
 7 10. The Newtonian Reflector is so called after Sir Isaac 
 Newton, its inventor. Instead of a concave mirror in the focus 
 of the speculum, he placed a plane mirror there, inclined so aa 
 to reflect the light to the side of the tube, where it was received 
 by the observer. 
 
 NEWTONIAN REFLECTOR. 
 
 The light fron the speculum is here shown falling upon the inclined mirror in the cen- 
 ter, and reflected out to the eye of the observer. 
 
 711. The Cassegranian Rejiecior is so called from M. Casse- 
 grain, its inventor. It resembles the Gregorian, except that the 
 speculum placed in the focus of the reflector is convex instead of 
 concave. 
 
 The Herschelian Reflector differs from all others, in having no 
 small reflector whatever ; the light being reflected back to a 
 focus at the top of the telescope, and near the edge of the tube, 
 where the eye-piece is placed, and where the observer sits look- 
 ing into the mirror with his back to the object. 
 
 HERSCHELIAN TELESCOPE. 
 
 Here the concave speculum is seen to be inclined a little to the lower side of the tube, 
 so that the parallel rays A are reflected back to the observer at B, at the fide of the 
 instrument, where the eye-piece is placed. 
 
 710. Newtonian reflectors? Til. Cassegranian ? Difference? ilerscheliau ? 
 eye-piece? How observer sit ? 
 
 14* 
 
DIFFERENT KIXDS OF TELESCOPES. 
 
 331 
 
 712. The first telescope constructed upon this plan was that 
 by Sir William Herschel, in 1782. This was called his 20 feet 
 reflector, and was the instrument with which he made many of 
 his observations upon the double stars. In 1789, he completed 
 his forty feet reflector, until recently the largest telescope ever 
 constructed. 
 
 Bin WILLIAM HERSCHEL'S FORTY FEET UUPLEUTOU. 
 
 713. The speculum of this instrument is 4 feet in diameter, 3|- 
 inches thick, and weighed, before being ground, 2,118 pounds. 
 
 712. First Herschelian telescope ? What called? Next? 713. Herschel's forty feet 
 reflector ? Size of Speculum ? Weight ? Tube ? Length and Weight ? How mounted ? 
 
332 ASTRONOMY. 
 
 The tube is made of sheet iron riveted together, and painted 
 within and without. 
 
 The length of the tube is 39 feet 4 inches, and its weight 8,260 pounds. It is elevated 
 or lowered by tackles, attached to strong frame-work ; and the observer, who sits in a 
 chair at the upper end of the tube, and looks down into the reflector at the bottom, \a 
 raised and lowered with the instrument. Three persons are necessary o use this tele- 
 scope one to observe, another to work the tube, and a third to note down the observa- 
 tions. A speaking tube runs from the observer to the house where the assistants are at 
 work By this telescope, the sixth and seventh satellites of Saturn were discovered ; 
 and it was the chief instrument used by its distinguished owner, in making the observa- 
 tions and discoveries which have immortalized his name, and which have so abundantly 
 enriched and advanced the science of astronomy. 
 
 LORD ROSSK'S GREAT RKFLECTINO TELES^)PB. 
 
 714. This is the largest reflecting telescope ever constructed. 
 The speculum, composed of copper and tin, weighed three tons as 
 it came from the mould, and lost about -Jth of an inch in grinding. 
 It is 5 inches thick, and 6 feet in diameter. It was cast on 
 the 13th of April, 1842, and was cooled gradually in an oven for 
 16 weeks, to prevent its cracking, by a sudden or unequal reduc- 
 tion of the temperature. This speculum has a reflecting surface 
 of 4071 square inches. The tube is made of deal wood, one 
 inch thick, and hooped with iron. Its diameter is seven feet, 
 and its length 56. 
 
 The entire weight of this telescope is twelve tons. It is mounted between two north 
 and south walls, 24 feet apart, 72 feet long, and 48 feet high. The lower end rests upon 
 an universal hinge. It can be lowered to the horizon, and raised to the zenith, and 
 lowered northward till it takes in the Pole Star. 
 
 Observer where? Usefulness? 7J4. Lord Rosse's telescope? Weight of speculum? 
 Diameter? Thickness? Cooling? Tube? Entire weight? How mounted? What 
 
OBSERV ATOPIES AND TELESCOPES. 
 
 333 
 
 OBSKRVATOEIES AND TELESCOPES IN THE TTNIT1D STATES. 
 
 
 
 THEI] 
 
 I TELE8C< 
 
 >PE8. 
 
 
 OBSERVATORIES. 
 
 When 
 procured. 
 
 Name of 
 maker. 
 
 Focal 
 length. 
 
 Aperture of 
 object glass. 
 
 Cost. 
 
 Tale College 
 
 1830 
 
 Dollond 
 
 ft. in. 
 10 
 
 inches. 
 5 
 
 $1 000 
 
 Wesleyan University 
 
 1836 
 
 
 7 
 
 6 
 
 1 000 
 
 Williams College. 
 
 (1836 
 
 Holcomb. 
 
 10 
 
 reflector. 
 
 
 Hudson, Ohio. 
 
 ) 1852 
 1837 
 
 A. Clark. 
 
 5 6 
 
 7 
 4 
 
 
 Philadelphia 
 
 1840 
 
 
 8 4 
 
 Af. 
 
 1 900 
 
 West Point 
 
 1841 
 
 
 g 
 
 6 
 
 
 Washington ; . . 
 
 1844 
 
 Merz 
 
 15 3 
 
 9-6 
 
 6000 
 
 Cincinnati .... .... 
 
 
 
 17 
 
 12 
 
 9437 
 
 Cambridge ... 
 
 1846 
 
 M 
 
 22 6 
 
 15 
 
 19 842 
 
 Dartmouth College 
 
 1848 
 
 H 
 
 g 
 
 6'4 
 
 
 Georgetown 
 
 1849 
 
 Simms 
 
 7 6 
 
 4-8 
 
 1 600 
 
 Erskine 
 
 
 Fitz 
 
 7 
 
 5'6 
 
 1 050 
 
 Shelby 
 
 1850 
 
 Merz 
 
 10 4 
 
 7-5 
 
 8500 
 
 Columbia (S. C.) College 
 
 1851 
 
 Fitz. 
 
 8 4 
 
 64- 
 
 l'200 
 
 Columbia (Mo.) 
 
 1852 
 
 
 5 
 
 4 
 
 225 
 
 Friends, Philadelphia 
 
 1846 
 
 H 
 
 7 
 
 5 
 
 
 Amherst College 
 
 1854 
 
 Clark. 
 
 8 6 
 
 7i 
 
 1 800 
 
 Michigan University 
 
 1853 
 
 Fitz 
 
 17 
 
 12i 
 
 e'ooo 
 
 Dudley, Albany, NY... 
 
 1857 ? 
 
 
 15 2 
 
 13 
 
 14500 
 
 Hamilton College 
 
 1857 
 
 
 16 
 
 13i 
 
 10 000? 
 
 J. Jackson, near Philadelphia. . . 
 Mr. Longstreet, Philadelphia 
 8. G. Gurnmere, Burlington, N. J. 
 
 B. Vanarsdale, Newark, N. J 
 
 W. 8. Van Duzee, Buffalo, N. Y. . 
 W. S. Dickie Elkton Ky. 
 
 1846 
 
 1847 
 J1850 
 j 1851 
 
 Fit! 
 
 It 
 
 8 4 
 7 
 5 
 7 
 8 4 
 11 
 6 
 
 63-10 
 5 
 4 
 5 
 
 if 
 
 *i 
 
 L833 
 900 
 425 
 750 
 1.000 
 2,220 
 300 
 
 D. Mosman, Bangor, Me 
 J. Campbell, New York 
 
 1852 
 
 " 
 
 5 
 10 
 
 4 
 8 
 
 225 
 1,150 
 
 L. M. Kutherford, New York .... 
 
 
 " 
 
 9 6 
 
 9 
 
 2.200 
 
 FOBEIGN OBSEKVATOKIES THEIR LATITUDE AND LONGITUDE. 
 
 OBSERVATORIES. 
 
 Longitude in Time. 
 
 Altona 
 
 Armagh 
 
 Berlin 
 
 Brussels 
 
 Cambridge 
 
 Cape of Good Hope. 
 
 Copenhagen 
 
 Dorpat 
 
 Dublin 
 
 Edinburgh. 
 
 Gottingen 
 
 Greenwich 
 
 Konigsberg 
 
 Munich 
 
 Palermo 
 
 Paris 
 
 Petersburg 
 
 Rome 
 
 Turin 
 
 Vienna 
 
 82 ' 45 
 
 21 
 
 80 
 
 51 
 
 12 
 
 56 
 
 40 53 
 
 22 
 
 23 
 
 51 
 
 31 
 
 23 
 
 42 
 
 8 45 
 6 44 
 
 50 13 
 
 56 
 
 53 
 
 h. m. 
 
 N. 
 
 12.7 N. 
 16.7 N. 
 
 10.7 N. 
 
 51.8 N. 
 3 S. 
 
 N. 
 
 47.1 N. 
 13 N. 
 
 23.2 N. 
 
 47.9 N. 
 88.2 N. 
 50.4 N. 
 
 N. 
 N. 
 N. 
 
 29.7 N. 
 54 N. 
 
 N. 
 
 6 
 
 85.5 N. 
 
 88 
 
 20 
 68 
 IT 
 
 18 
 50 
 46 
 25 
 12 
 39 
 
 
 22 
 46 
 53 
 9 
 2 1 
 49 
 30 
 
 s. 
 
 46.2 
 35.5 
 34.9 
 27.2 
 23.5 
 56.0 
 19.3 
 54.6 
 22 
 43.0 
 46.8 
 0.0 
 0.4 
 25.4 
 25.5 
 21.5 
 13.5 
 54 7 
 48.4 
 32.6 
 
 E. 
 E. 
 E. 
 E. 
 E. 
 E. 
 W. 
 
 E.' 
 
 E. 
 E. 
 E. 
 E. 
 E. 
 E. 
 E. 
 E. 
 
 699. Public observatories in this country? Largest telescope ? Table? PrivciO 
 obser vatories names ? Telescopes by whom mostly mde ? What other table ? 
 
334: ASTRONOMY. 
 
 CHAPTER XX. 
 PROBLEMS AND TABLES. 
 
 PROBLEM I. 
 TO CONVERT DEGREES, ETC., INTO TIME. 
 
 RULE I Divide the degrees by 15, for hours ; and multiply thi 
 lemainder, if any, by 4, for minutes. 
 
 2. Divide the odd minutes and seconds in the same manner b; 
 15 for minutes, seconds, &c., and multiply each remainder by 4 
 for the next lower denomination. 
 
 EXAMPLE 1. Convert 32 34' 45" into time. 
 
 Thus, 32-f-15:=2h. 8' 
 
 34 -M5 = 2 16* 
 
 45 -v-15=r 3 
 
 Ans. 32 34' 45*=2h. 10' 19* 
 
 EXAMPLE 2. If it is 12 o'clock at this place, what is the tim< 
 20 east of us ? 
 
 Thus fifteen in 20, once, and five over ; the once is 1 hour 
 and the 5 multiplied by 4, gives 20 minutes ; the time is thei 
 1 hour and 20 minutes past 12. 
 
 EXAMPLE 3. The longtitude of Hartford is 72 50' west o 
 Greenwich; what time is it at Greenwich when it is 12 o'clock a 
 Hartford ? Ans. 4h. 51m. 20s. 
 
 EXAMPLE 4. When it is 12 o'clock at Greenwich, what is th< 
 time at Hartford ? Ans. 7h. 8m. 40s. 
 
PROBLEMS AND TABLES. 335 
 
 PROBLEM II. 
 TO CONVERT TIME INTO DEGREES, ETC. 
 
 RULE. Multiply the hours by 15, and to the product add one- 
 fourth of the minutes, seconds, <fec., observing that every minute 
 of time makes , and every second of time \'. 
 
 EXAMPLE 1. In 2 hours, 10 minutes, and 19 seconds; how 
 many degrees? 
 
 Thus; ~~ 2h. 10m. 19. 
 
 15 
 
 30 5 
 
 Add 10 quarters, or | of the min. 2 30' 
 Add 19 quarters, or of the sec. 4 45' 
 
 Ans. 32 34' 45* 
 
 Ex. 2. When it is 12 o'clock at Hartford, it is 4 hours, 51 
 minutes, and 20 seconds past noon at Greenwich ; how many 
 degrees is Hartford west of Greenwich ? 
 
 Thus : 15 times 4 is 60 added to of 51, is 72 45 ff , and 
 this increased by \ of 20, is 72 50'. Ans. 
 
 Ex. 3. A Liverpool packet, after sailing several days from 
 New York, finds the time by the Sun 2 hours and 40 minutes 
 later than by the ship's chronometer : how far has the ship pro- 
 giessed on her way ? 
 
 Ex. 4. A vessel leaves Boston, and having been tossed about 
 in foul weather for some days, finds, that when it is 12 o'clock 
 by the Sun, it is only 11 o'clock and 50 minutes by the watch ; 
 is the vessel east or west of Boston ; and how many degrees ? 
 
 Ex. 5. The moment of greatest darkness, during the annular 
 eclipse of 1831, took place at New Haven, 10 minutes after 1 
 o'clock. A gentleman reports that it happened precisely at 1, 
 where he observed it ; and another that it was 5 minutes after 
 1 where he saw it ; Query. How far east or west were these 
 gentlemen from each other, and how many degrees from New 
 Haven ? 
 
336 ASTEONOMY. 
 
 PROBLEM III. 
 
 TO FIND WHAT STARS ARE ON THE MERIDIAN AT NINE O'CLOCK IJ 
 THE EVENING OF ANY GIVEN DAT. 
 
 RULE. Look for the given day of the month, at the botton: 
 of the maps, and all the stars having the same degree of righl 
 ascension will be on the meridian at that time. 
 
 EXAMPLE 1. What stars will be on the meridian at 9 o'clock 
 the 19th of January? 
 
 Solution. On Map III. I find that the principal stars stand- 
 ing over against the 19th of January, are Rigel and Capella. 
 
 Ex. 2. What stars are on the meridian the 20th of Decem- 
 ber ? Ans. Menkar and Algol. 
 
 PROBLEM IV. 
 ANY STAR BEING GIVEN, TO FIND WHEN IT CULMINATES. 
 
 RULE. Find the star's right ascension in the table, or by the 
 map (on the equinoctial), and the day of the month at the top 
 or bottom of the map will be the day on which it culminates at 
 9 o'clock. 
 
 EXAMPLE 1. At what time is the bright star Sirius on the 
 meridian ? 
 
 Solution. I find by the table, and by the map, that the right 
 ascension of Sirius is 6 -hours and about 38 minutes; and the 
 time corresponding to this, at the bottom of the map is the llth 
 of February. 
 
 Ex. 2. At what time is Alpheratz, in the head of Andromed^ 
 on the meridian ? Ans. The 9th of November. 
 
PROBLEMS AND TABLES. 337 
 
 PROBLEM V. 
 
 THE J1IGHT ASCENSION AND DECLINATION OF A PLANET BEING 
 GIVEN, TO FIND ITS PLACE ON THE MAP. 
 
 RULE. Find the right ascension and declination of the planet 
 on the map, and that will be its place for the given day. 
 
 EXAMPLE 1. Venus's right ascension on the 1st of January, 
 1833, was 21 hours, 30 minutes, and her declination 16f south ; 
 required her situation on the map ? 
 
 Solution. On the right hand of the Plate II. I count off 16f 
 from the equinoctial, on the marginal scale south, and from that 
 point, 30 minutes to the left or just half the distance between the 
 XXI. and XXII. meridian of right ascension, and find that 
 Venus, that day, is within two degrees of Delta Capricorni, neai 
 the constellation Aquarius, in the zodiac. 
 
 Ex. 2. Mars' right ascension on the 13th of March, 1833, is 
 5 hours, 1 minute, and his declination 24i north ; required his 
 situation on the map ? 
 
 Solution. I find the fifth hour line or meridian of right ascen- 
 sion on Plate III.., and counting upward from the equinoctial 
 24i, I find that Mars is between the horns of Taurus, and about 
 5 S. W. of Beta Auriga. 
 
 Ex. 3. Required the position of Jupiter and Saturn on the 
 13th of February and the 25th of May? 
 
 PROBLEM VI. 
 
 TO FIND AT WHAT MOMENT ANY STAR WILL PASS THE MERIDIAN ON 
 A GIVEN DAY. 
 
 RULE. Subtract the right ascension of the Sun from the 
 star's right ascension, found in the tables : observing to add 24 
 hours to the star's right ascension, if less than the Sun's, and 
 the difference will show how many hours the star culminates 
 after the Sun. 
 
338 ASTRONOMY. 
 
 EXAMPLE 1. At what time willProcyon pass the meridian on 
 the 24th of February ? 
 
 Solution. R. A. of Procyon, 7h. 30m. 33s. + 24h. 
 
 31 30' 33* 
 
 R. A. of Sun, 24th Feb. 22 29 1 
 
 Ans. 1 I 32~ 
 
 That is lin. 32s. past 9 o'clock in the evening. 
 
 Ex. 2. At what time will Denebola pass the meridian on the 
 first of April ? 
 
 Solution.R. A. of Denebola is llh. 40' 32* 
 
 R. A. of Sun, April 1, 41 25 
 
 Ans. "lO 59 7~ 
 That is, at 59 minutes, 7 seconds, past 10 in the evening. 
 
 Ex. 3. At what time on the first day of each month, from 
 January to July, will Alcyone, or the Pleiades, pass the meri- 
 dian ? 
 
 Ex. 4. At what time will the Dog-Star, or Sirius, culminato 
 on the first day of January, February, and March 1 
 
 Ex. 5. How much earlier will Spica Yirginis pass the meri 
 dian on the 4th of July, than on the 15th of May ? 
 
 Ans. 3 hours, 25 minutes. 
 
 PROBLEM VII. 
 
 TO FIND THE SUN'S LONGITUDE OR PLACE IN THE ECLIPTIC, ON ANY 
 GIVEN DAY. 
 
 RULE. On the lower scale, at the bottom of the Planisphere 
 (Map VIII.) look for the given day of the month ; then the sign 
 and degree corresponding to it on the scale immediately above it 
 will show the Sun's place in the ecliptic. 
 
 EXAMPLE 1. Required the Sun's longitude, or place in the 
 ecliptic, the 16th of September. 
 
 Solution. Over the given day of the month, September 16th, 
 stands 5 signs and 23 degrees, nearly, which is the Sun's place in 
 the ecliptic at noon on that day ; that is, the Sun is about 23 
 degrees in the sign Virgo. 
 
PROBLEMS A>D TABLES. 339 
 
 N.B.- If the 5 signs be multiplied by 80, and the 23 degrees be added to it, it will give 
 Jte looitude in degrees, 173. 
 
 Ex. 2. Required the Sun's place in the ecliptic at noon, OL 
 the 10th of March. 
 
 PROBLEM VIII. 
 
 GIVEN THE SUN'S LONGITUDE, OR PLACE IN THE ECLIPTIC, TO FIND HIS 
 RIGHT ASCENSION AND DECLINATION. 
 
 RULE. Find the Sun's place in the ecliptic (the curved lice 
 which runs through the body of the planisphere), and with a 
 pair of compasses take the nearest distance between it and the 
 nearest meridian, or hour circle, which being applied to the gra- 
 duated scales at the top or bottom of the planisphere (measur- 
 ing from the same hour circle), will show the Sun's right ascen- 
 sion. Then take the shortest distance between the Sun's place 
 in the ecliptic and the nearest part of the equinoctial, and apply 
 it to either the etist or west marginal scales, and it will give the 
 Sun's declination. 
 
 EXAMPLE 1. The Sun's longitude, September 16th, 1833, is 
 5 signs, 23 degrees, nearly ; required his right ascension, and 
 declination. 
 
 Solution. The distance between the Sun's place in the eclip- 
 tic and the nearest hour circle being taken in the compasses, and 
 applied to either the top or bottom graduated scales, shows the 
 right ascension to be about 11 hours 35 minutes ; and the dis- 
 tance between the Sun's place in the ecliptic, and the nearest 
 pert of the equinoctial, being applied to either the east or west 
 marginal scales, shows the declination to be about 2 45', which 
 is to be called north, because the Sun is to the northward of 
 the equinoctial ; hence the Sun's right ascension, on the given 
 day, at noun, is about 11 hours 35 minutes, and his declination 
 2 45' N. 
 
 Ex. 2. The Sun's longitude, March 10th. 1833, is 11 signs, 
 19 degrees, nearly ; required his right ascension and declin? 
 tion ? 
 
 Ans. R. A. 23h. 21m. Deci. 4 11' nearly. 
 
 PROBLEM IX. 
 TO FIND THE RIGHT ASCENSION OF THE MERIDIAN AT ANY 5IVEN TIME. 
 
 RLLE. Find the Sun's place in the ecliptic by Problem IX. , 
 and his right ascension by Problem X., to the eastward of 
 
340 ASTRONOMY. 
 
 which count off the given time from noon, and it will show the 
 right ascension of the meridian, or mid-heaven. 
 
 EXAMPLE 1. Required the right ascension of the meridian 9 
 hours, 25 minutes past noon, September 16th, 1833 ? 
 
 Solution. By Problems IX. and X., the Sun's right ascen- 
 sion at noon of the given day, is 11 hours 35 minutes ; to the 
 eastward of which, 9 hours and 25 minutes (the given time) 
 being counted off, shows the right ascension of the meridian to 
 be about 21 hours. 
 
 Ex. 2. Required the right ascension of the meridian at 6 
 hours past noon, March 10th, 1833 ? 
 
 Solution. By Problems IX. and X., the Sun's right ascension 
 at noon of the given day, is 23 hours and 21 minutes j to tht 
 eastward of which, the given time, 6 hours, being counted off, 
 shows the right ascension of the meridian to be about 5 hours, 
 21 minutes. 
 
 REMARK. In this example, it may be necessary to observe, that where the eastern, or 
 left-hand extremity of the planisphere leaves off, the western, or right-hand extremity 
 begins ; therefore, in counting off the given time on the top or bottom graduated scales, 
 the reckoning is to be transferred from the left, and completed on the right, as if the two 
 outside edges of the planisphere were joined together. 
 
 PROBLEM X. 
 
 TO FIND WHAT STARS WILL BE ON OR NEAR THE MERIDIAN, AT ANY 
 GIVEN TIME. 
 
 RULE. Find the right ascension of the meridian by Problem 
 XI., over which lay a ruler, and draw a pencil line along its 
 edge from the top to the bottom of the planisphere, and it will 
 show all the stars that are on or near the meridian. 
 
 EXAMPLE 1. Required what stars will be on or near the 
 meridian at 9 hours, 25 minutes past noon, Sept. 16th, 1833 ? 
 
 Solution. The right ascension of the meridian by Problem 
 XI. is 21 hours : this hour circle, or the line which passes up 
 and down through the planisphere, shows that no star will be 
 directly on' the meridian at the given time ; but that Alderamin 
 will be a little to the east, and Deneb Cygni a little to the west 
 of it ; also Zeta Cygni, and Gamma and Alpha in the Little 
 Horse, very near it on the east. 
 
 PROBLEM XI. 
 
 MULE. As the Sun's horizontal parallax is to radius, so if 
 tue semi-diameter of the Earth to its distance from the Sun. 
 
PROBLEMS AND TABLES. 3il 
 
 By Logarithms, As tangent of the Sun's horizontal parallax 
 is to radius, so is the Earth's semi-diameter to her mean distance 
 from the Sun. 
 
 8'.5776: 206264-.8 : :3962 : 95,273,869 miles. 
 
 y Logarithms, 
 
 As tangent of the Surf's horizontal parallax, 8' .5776= 5.6189407 
 Is to radius, or 90% =10-0000000 
 
 So is the Earth's serai-diameter, 8962= 8.5979143 
 
 To the Earth's distance, 95,273,869= 7.9789738 
 
 PROBLEM XII. 
 
 TO FIND THE DISTANCE OF ANY PLANET FROM THE SUN, THAT OF THB 
 EARTH BEING KNOWN. 
 
 RULE. Divide the square of the planet's sidereal revolution 
 round the Sun, by the square of the Earth's sidereal revolution, 
 and multiply the cube root of the quotient by the Earth's mean 
 distance from the Sun. 
 
 By Logarithms, From twice the logarithm of the planet's 
 sidereal revolution, subtract twice the logarithm of the Earth's 
 sidereal revolution, and to one-third of the remainder, add the 
 logarithm of the Earth's mean distance from the Sun. 
 
 EXAMPLE. Required Mercury's mean distance from the Sun, that of the Earth being 
 V5,273,S69 miles. 
 
 Mercury's sidereal revolution is 87.969258 days, or 7600543'. 8912: the Earth's sidereal 
 revolution is 865.256374417 days, or 
 
 3155S15V.5 7600543.9 
 
 01558151'. 5 7600543.9 
 
 995916962096952 25 by which divide 57768267575827.21 
 
 and the quotient will be 0.052005106713292, the cube root of which is 0.3870977, and this 
 multiplied by 94,881,891, gives 86,727,607 miles, for Mercury's distance from the Sun. 
 This problem may be performed by logarithms in as many minutes as the former method 
 requires hours, 
 
 Mercury's Sid. Rev. 7600543'.9 log.=6.880S447 x 2 13.7616894 
 
 Earth's Sid. Rev. 31558151'. log. = 7.4991302 * 2 14.9982604 
 
 X) 2.7634290 
 
 Add log. of the Earth's mean distance, 
 
 Mercury's distance, 86,880,422. Ans. 7.5667835 
 
 If the pupil have not already learned the use of logarithms, this problem will satisfy 
 him of their unspeakable advantage over all other modes of computation. By reviewing 
 the above calculation, he will perceive that instead of multyplying 31558151'.5 by itself, 
 he need only multiply its logarithms by two ! and instead of extracting the cube root of 
 0.058005106713292, he need only divide its logarithm by three ! and instead of multiply- 
 ing 0.3870977, by 95,273,869, he need only add their logarithms together. He need not 
 think himself a dull scholar, if by the former method he come to the true result in fiv* 
 ttcurs; nor remarkably quick, if by the latter he come to it in^oa minutes. 
 
 PROBLEM XIII. 
 TO FIND THE HOURLY MOTION OF A PLANET IN ITS ORBIT. 
 
 RULE. Multiply the planet's .mean distance from the Sun by 
 
342 
 
 ASTRONOMY. 
 
 C. 28 3 1853, and divide the product by the time of the planet's 
 sidereal revolution, expressed in hours, and the decimals of an 
 hour. 
 
 By Logarithms. Add 0.7981799 to. the logarithm of the 
 'planet's mean distance from the Sun, and from the sum subtract 
 the logarithm of the planet's revolution* expressed in hours. 
 
 EXAMPLE. Required the Earth's hourly motion in its orbit. 
 
 Log. of Earth's distance=7.978073S + 0.7981799= 8.7771587 
 
 Subtract hog. of Earth's revolution 8.9428090 
 
 Gives Earth's horary motion, 68,288 miles, 4.834344T 
 
 PROBLEM XIV. 
 TO FIND THE HOURLY MOTION OF A PLANET ON ITS AXIS. 
 
 RULE. Multiply the diameter of the given planet by 3.14159, 
 and divide the product by the period of its diurnal rotation. 
 
 By Logarithms. Add 4.0534524 to the logarithm of the 
 planet's diameter, and from the sum subtract the logarithm of 
 its diurnal rotation, expressed in seconds. 
 
 Earth's diameter, 7924 log. = 
 
 Add log. of 8600' + log. of 8.14159 = 4.0584524 
 
 7.9523969 
 Subtract log. diurnal rotation, 23h. 56' 4".09 = 4.9353263 
 
 Ana. 1040.09 miles = 8.0170706 
 
 PROBLEM XV. 
 TO FIND THE RELATIVE MAGNITUDE OF THE PLANETS. 
 
 RULE. Divide the cube of the diameter of the larger planet 
 by the cube of the diameter of the less. 
 
 By Logarithms. From three times the logarithm of the 
 larger, subtract three times the logarithm of the less. 
 
 EXAMPLE. How much does the size of the Earth exceed that of the Moon ? 
 Earth's diameter, 7912 log. 8.8982863 x 3= 11.6948589 
 
 Moon's diameter, 2160 log. 8.3343376x3= 10.0080128 
 
 The Earth exceeds the Moon, 49.1865 times. Ans. 1.6918461 
 
 In this example, 7912 miles is assumed as the mean between the Earth's equatorial 
 and polar diameter : the former being 7924, and the latter 7898 miles. 
 
 PROBLEM XVI. 
 
 TO FIND THE PROPORTION OF SOLAR LIGHT AND HEAT AT EACH OF 
 THE PLANETS. 
 
 RULE. Divide the square of the planet's greater distance 
 from the Sun, by the square of the less. Or, subtract twice the 
 logarithm of the greater distance from twice the logarithm of 
 the less. 
 
PROBLEMS AND TABLES. 
 
 343 
 
 EXAMPLE. How much greater is the Sun's light and -heat at 
 Mercury, than at the Earth ? 
 
 Log. of Earth's distance 
 
 " of Mercury's 
 Ans. 6.6736 times. greater = 
 
 7.9789738x2=15.9579176 
 
 7.5667959 x 2=15.1335918 
 
 O.S243553 
 
 PROBLEM XVII. 
 TO FIND THE CIRCUMFERENCE OF THE PLANETS. 
 
 RULE. Multiply the diameter of the planet by 3.14159, or, 
 add the logarithm of the planet's diameter to 0.497149 9. 
 
 PROBLEM XVIII. 
 TO FIND THE CIRCUMFERENCE OF THE PLANETARY ORBITS. 
 
 RULE. Multiply the planet's mean distance from the Sun by 
 c. 2831853 ; or, to the logarithm of the planet's mean distance, 
 add 0.7981799, and the sum will be the logarithm of the answer. 
 
 PROBLEM XIX. 
 
 TO FIND IN WHAT TIME ANY OF THE PLANETS WOULD FALL TO THE 
 SUN, IF LEFT TO THE FORCE OF GRAVITATION ALONE. 
 
 KULE. Multiply the time of the planet's sidereal revolution 
 by 0.176776 ; the result will be the answer. 
 
 By Logarithms. From the logarithm of the planet's sidereal 
 revolution, subtract 0.7525750, and the remainder will be the 
 logarithm of the answer, in the same denomination as the side- 
 real revolution. 
 
 Required the times, respectively, in which the several planets would, fall to the Sun oy 
 the force 01 gravity. 
 
 Planets would fall to the Sun. 
 
 Days. H. M. S. 
 
 Logarithms. 
 
 Mercury, 
 Venus, 
 Earth, 
 Mars, 
 Jupiter, 
 Saturn, 
 Herschel, 
 Moon to the Earth, 
 
 15 13 13 16 
 89 17 19 22 
 64 13 88 55 
 121 10 86 3 
 265 21 33 35 
 1901 23 24 4 
 5424 16 52 1 
 4 19 54 57 
 
 6.1282686 
 6.5355424 
 6.7465357 
 7.0208817 
 7.8206849 
 8.2157186 
 8.670S897 
 5.6204459 
 
 THE END. 
 
SXPLAJSTATIONS AND PROBLEMS 
 
 ADAPTED TO 
 
 WGITALL'S PLANISPHERE. 
 
 TO BE USED IN CONNECTION WITH THE CELESTIAL ATLAS. 
 
 t 
 
 NOTE. This is a movable Planisphere, invented and copy- 
 righted by Henry Whitall, and for sale by the publishers of Bur- 
 ritt's GEOGRAPHY OF THE HEAVENS, exhibiting the stars that are ris- 
 ing, setting, on the meridian, or their position in the firmament, as 
 seen in the United States every minute, for HUNDREDS OF YEARS. 
 The right ascension and declination of the sun, moon, stars, and 
 planets ; the equation of time (sun fast or slow) ; harvest-moon ; 
 sun and moon lunning high and low; the milky way, as it 
 changes its course for every hour ; change of seasons, &c., can be 
 readily explained with this invaluable substitute for a Celestial 
 Globe, " being as much better as it is cheaper" than that expen- 
 sive school apparatus. 
 
 It is light, portable, accurate, containing much within a small 
 space, and is sold for THREE DOLLARS, which price brings it within 
 the means of all lovers of science, and of every teacher who may 
 desire his pupils to become acquainted with the wonders of the 
 heavens. This knowledge need no longer be confined to the 
 learned few, for the use of this Planisphere will enable any one to 
 become familiar with the stars and constellations, and will prove 
 pleasing and instructive. The desideratum so long desired is 
 thus supplied, and reading the stars is no longer a mystery. 
 
EXPLANATIONS AND PROBLEMS. 
 
 PROBLEMS. 
 
 WHICH MAY BE PERFORMED ON THE PLANISPHERE. 
 
 THE DAY OF THE MONTH, THE HOUR, AND MINUTE BEING GIVEN, 
 TO FIND WHAT STAES ARE RISING, SETTING, ON THE MERIDIAN, 
 OR IN ANY PART OF THE FIRMAMENT. 
 
 APPLICATION. Bring the given hour and minute opposite the 
 given day of the month ; hold the zenith over head, with the 
 meridian in a line north and south ; the Planisphere will then 
 represent in miniature the constellations visible in the heavens at 
 that time. The stars which are rising are near the eastern, and 
 those setting, near the western horizon. Thus can be seen the 
 stars in any part of the heavens, at every minute, sufficiently 
 accurate for most practical purposes. 
 
 EXAMPLE. Where will An-drom'e-da be at 10 o'clock on the 10th of 
 November? (29.) Ans. Directly over head. 
 
 EXAMPLE. Where will the Royal Family (Ce-phe'us, Cas-si-o-pe'ia, An- 
 drom'e-da, and Per'se-us) be, at 4 o'clock on the morning of November 10th ? 
 Ans. Setting in the N. W. 
 
 EXAMPLE. On what day will the Royal Family be setting in the North- 
 west at 9 o'clock, evening ? Ans. About the 4th of March. 
 
 EXAMPLE. Where will $ Ursa Major (Megres) be, at 9 o'clock on the 10th 
 cf May? (149.) Ans. On the meridian. 
 
 EXAMPLE. Where will fi Leo (Denebola) be, at 9 o'clock on the 3d of 
 May ? (132.) Ans. On the meridian. 
 
 TELESCOPIC OBJECTS. 
 
 The right ascension of telescopic objects is given in hours and 
 minutes. To find their place in the heavens, bring the hour and 
 minute of R. A. to the arrow, near March 22d, on the outer circle ; 
 under the declination, marked on the meridian, will be the situation 
 of the object ; on the equator, opposite 0, can be seen the degrees 
 of R. A. 
 
 Should the R. A. be 13 hours, bring the arrow to 1, past raid- 
 night ; for 14 hours, bring it to 2 and so on. 
 
ADAPTED TO WHITALL^S PLANISPHERE. 
 
 EXAMPLE. a Yirginis (Spica), R. A. 13 hours, 16 minutes, 47 sccondj; 
 turn the arrow to 1 hour 16 minutes past midnight, and its place is 10 
 deg. 19m. 5s. south of the equator. (Page 83.) 
 
 EXAMPLE. a Bo-o'tis (Arcturus), R. A. 14 hours, 8 minutes, 22 seconds; 
 turn the arrow to 2 hours, 8 minutes, 22 seconds past midnight; its place 
 will be under the 20th deg. north declination, marked on the meridian. 
 (Page 88.) 
 
 EXAMPLE. a Scorpii (Antares), R. A. 16 hours, 19 minutes, 36 seconds; 
 turn the arrow to 4 hours, 19 minutes, 36 seconds past midnight, and its 
 place is 26 deg. 04m. 3s. south declination. (Page 102.) 
 
 EXAMPLE. 61 Cygni, the most remarkable known in the heavens, R. 
 A. 20 hours, 59 minutes, 43 seconds ; declination N". 37 deg. 58m. ; is 
 regarded as one of the nearest to our system. (Page 126.) Where is it on 
 the Planisphere? Ans. In Cygnus, the Swan. 
 
 EXAMPLE. A gorgeous cluster, R. A. 2 hours, 8 minutes, 58 seconds > 
 declination N. 56 deg. 24m. ; is one of the most magnificent objects in the 
 heavens. (Page 37.) "Where is it ? Ans. In the sword-handle of Perseus. 
 
 THE RIGHT ASCENSION AND DECLINATION OF THE SUN, MOON, 
 PLANET, STAR, OR COMET BEING GIVEN, TO FIND ITS PLACE ON 
 THE PLANISPHERE. 
 
 Bring the graduated side of the meridian to the degrees of 
 right ascension marked on the equator, or bring the hours and 
 minutes of R. A. opposite the arrow, near March 22d; its place 
 will be under the declination marked on the meridian. 
 
 EXAMPLE. The direction of the sun and solar system is towards right 
 ascension 259 deg., declination north 35 deg. In what constellation is that 
 point situated ? (571.) Ans. Hercules. 
 
 EXAMPLE. f\ Tauri (Alcyone), the supposed central sun, R. A. 3 hours, 37 
 minutes, 57 seconds; declination N. 23 deg. 36m. Where is it? (66.) 
 Ans. One of the Pleiades. 
 
 EXAMPLE. What star has R. A. 18 hours, 31 minutes, 30 seconds; de- 
 clination N. 38 deg. 38m. ? (Page 115.) Ans. a Lyra (Vega). 
 
 TO FIND THE RIGHT ASCENSION AND DECLINATION OF THE SUN 
 FOR ANY DAY IN THE YEAR. 
 
 The Sun's place among the stars is on the ecliptic, where 
 the day of the month is. Bring the meridian to the day requir- 
 ed. The declination will be found on the meridian opposite the 
 Oay, and the degrees of right ascension on the equator, under the 
 
EXPLANATIONS AND PROBLEMS 
 
 meridian ; the hours and minutes opposite the arrow, reading 
 from 12 o'clock, noon, to 24 hours. 
 
 "What is the right ascension and declination of the sun on the 20th of 
 March ? (616.) Ans. 0. 
 
 What is the right ascension and declination of the sun on the 21st of 
 June ? Ans. 90 deg. or 6 hours right ascension, 23 deg. north declination. 
 
 "What is the right ascension and declination of the sun on the 21st of 
 December? Ans. 270 deg. or 18 hours right ascension, and 23^ deg. south 
 declination, 
 
 On what day of the month does the sun enter each of the signs? (618.) 
 
 Solution : The day of the month is marked opposite each sign on the 
 ecliptic. 
 
 What is the declination and right ascension of the sun on the 5th of 
 June ? Ans. 22 deg. north decimation, 73f deg. or 4 hours 55 minutes 
 right ascension. 
 
 CHANGE OF SEASONS DIFFERENT LENGTHS OF DAYS AND NIGHTS. 
 
 Bring March 20th on the ecliptic to the east horizon ; at March 
 20th on the outer circle, will be the mean time of the sun's 
 rising. Bring March 20th to west horizon, and see at March 
 20, outside, the mean time of the sun's setting. The rising and 
 setting will be later every day until the 21st of June, when the 
 days decrease until December 21st. (616 and 617.) 
 
 AMONG ALL THE STARS VISIBLE ON A CLEAR EVENING, WHICH IS 
 JUPITER ? WHICH IS SATURN, OR ANY OTHER OF THE PLANETS, OR 
 THE MOON ? 
 
 Find in the almanac the time at which the given planet rises, 
 souths, or sets. Bring that time to the day of the month ; if ris- 
 ing, its place will be where the eastern horizon meets the ecliptic ; 
 if southing, where the meridian meets the ecliptic; if setting, 
 where the western horizon meets the ecliptic. Notice its place 
 umong the stars, and then bring the time of observation to the day 
 of the .month, and the position of the planet in the heavens will 
 be shown. Or, find in the almanac the nearest day upon which 
 Vhe pknet is in conjunction with the moon ; and find the POSI- 
 TION OF THE MOON on that day in like manner, which will bo 
 nearly the place of the planet on the given day. 
 
 EXAMPLE. Where was the moon at 7 o'clock on the evening 
 18th, 1863? 
 
ADAPTED TO WHITALI/S PLANISPHERE. 
 
 Solution. We see by almanac that the moon southed at 2 hours 58 minutc-b 
 P. M. Bring this time to the 18th of August, and under the meridian on 
 the ecliptic 12 deg. in the sign Libra, constellation Virgo, will be the moon's 
 ^lace on the 18th of August. To find its position in the heavens, bring 7-? 
 o'clock P. M. to August 18th, and 12 deg. Virgo (the moon's place) will bo 
 about an hour above the "W. S. W. horizon. 
 
 EXAMPLE. Where were Saturn and Venus at the above time ? Ans. By 
 referring to the almanac, we see that the/ were in conjunction with the 
 tnoon. 
 
 SIDEREAL TIME. 
 
 jBring the given mean (clock) time to the day of the momn ; 
 the corresponding sidereal time will be found opposite the 
 arrow. (392.) 
 
 EXAMPLE. August 18, 1863, when the moon is on the meridian at 2 
 hours 58 minutes P. M., what is the sidereal tune ? Ans. 12 hours 46 
 minutes. The right ascension. 
 
 EXAMPLE. When the sun is on the meridian December 22d, what is the 
 sidereal time? Ans. 18 hours 2m. E. A. of the sun. 
 
 EQUATION OF TIME. TO FIND HOW MUCH THE SUN IS FAST OR SLOW. 
 
 Bring the meridian to the given day on the ecliptic ; opposite 
 the same day, on the outer circle, will be the time the sun is on the 
 meridian ; if before 12 o'clock, the sun is fast; if after 12 o'clock, 
 the sun is slow. (397.) 
 
 EXAMPLE. Bring the meridian to November 10th, on the ecliptic; 
 opposite that date will be found 11 hours 44 minutes, the sun being 16 
 minutes fast. 
 
 EXAMPLE. Is the sun fast or slow September 1st? how much? (397.) 
 Ans. Sun and clock agree. 
 
 EXAMPLE. How many minutes is the sun slow or fast on the 10th of 
 February ? Ans. 14 minutes slow. 
 
 EXAMPLE. When the sun is on the meridian July 31st, what is the true 
 clock time ? Ans. 6 minutes past 12. 
 
 EXAMPLE. How shall we get a meridian line to-day at noon ? Ans. 
 When the sun is on the meridian, mark its shadow for the meridian. 
 
 TO FIND THB VARIATION OF THE MAGNETIC NEEDLE, OR TO GET A 
 MERIDIAN LINE. (46, 192-194.) 
 
 Bring the meridian to 17 on the equator, the arrow will point 
 a' 1 hour 9 minutes, the right ascension of the north pole star 
 
EXPLANATIONS AD PROBLEMS. 
 
 opposite the day of every month will be found the time the north 
 pole star is on the meridian ; a correct range at that time will be 
 a true meridian. Six hours after, it will be at its greatest elonga- 
 tion west ; and six hours later, on the meridian below the pole ; 
 ind six hours later, at it's greatest elongation east. 
 
 EXAMPLE. At what time can we get a meridian line December 10th? 
 ins. 7 hours 50 minutes, evening. 
 
 EXAMPLE. At what minute, February 20th, can we get the variation of 
 Lite compass ? Ans. 6 minutes past 3 in the morning. 
 
 EXAMPLE. When will the polar star be at its greatest elongation east 
 August 23d ? Ans. At 9 in the evening. 
 
 TO TELL THE COURSE AND POSITION OP THE MILKY WAY ANY 
 GIVEN TIME. 
 
 Bring the given time to the day of the month ; the course and 
 position can be readily traced on the Planisphere. (256-260.) 
 
 "What will be the course of the Milky Way on the 5th of September, 
 at 6, 9, H and 6 o'clock? Ans. At 6 o'clock evening, starting from northern 
 horizon to east of zenith, to southern horizon. At 9 o'clock it appears in 
 the N. E., hi zenith, to S. "W. At H o'clock it appears in the east, passes 
 the meridian at 60 deg. north, to the west. At 6 o'clock morning, it appears 
 hi the S. E., passes the zenith to the N. W. 
 
 TO EXPLAIN THAT IN SUMMER, WHEN THE SUN RUNS HIGHEST, THE 
 FULL MOON RUNS LOWEST ; AND IN WINTER, WHEN THE SUN RUNS 
 LOWEST, THE FULL MOON RUNS HIGHEST. (421.) 
 
 Bring the graduated side of the meridian to the 21st of June 
 on the ecliptic, the sun's place among the stars at his greatest dis- 
 tance north ; should the moon full on that day, she will be at hei 
 greatest distance south, in the opposite part of the sky ; shown by 
 bunging the meridian to the 21st of December on the ecliptic, at 
 her greatest distance south. Bring the first date to the W. N. W. 
 horizon, and the second date will be near the E. S. E. ; when the 
 sun sets at his greatest distance north in summer, the full moon 
 will rise at her greatest distance south. 
 
 For winter, reverse the above, by bringing the second date near 
 the W. S. W., showing the sun's setting at his greatest distance 
 south, while the full moon can be rising in the E. N. E., at her 
 greatest distance nortti. 
 
By the almanac, see when the moon is full, and the time sne la 
 south, by which find her place on the Planisphere. 
 
 Where will the full moon of June be found ? Ans. At her greatest dis- 
 tance south. 
 
 "Where will the full moon in December be found? Ans. At her greatest 
 distance north. 
 
 The Harvest-Moon (626-635), so called in some parts of 
 Europe, is of great benefit to the husbandman, by lengthening the 
 day while gathering the fruits of 'the earth, and takes place at the 
 full moon in September, when the moon rises for several evenings 
 near the same hour. Shown on the Planisphere by bringing 6 
 o'clock, evening, to the 20th day of September. The eastern 
 horizon, first meridian, ecliptic, and equator, meet at the vernal 
 equinox. Should the moon be full on that day, and rise at the 
 vernal equinox at 6, on the following evening she will have moved 
 eastward about 13 deg. ; then turn the horizon until 13 deg. on the 
 ecliptic rises, opposite the 21st day of September, will be found the 
 time of the moon's rising to be about 28 minutes later. Bring 13 
 deg. more above the horizon, opposite the 22d of September, will 
 be found the time of the moon's rising to be about 28 minutes 
 later. The ecliptic being nearly parallel to the horizon, it changes 
 less than half an hour per night. Now turn 6 o'clock, evening, to 
 March 22d, the eastern horizon meets the autumnal equinox. 
 Bring 13 deg. of the ecliptic up, and opposite March 23d will be 
 found *7 o'clock, making more difference in one day than there 
 was before shown in two days ; the ecliptic being now nearly 
 perpendicular to the horizon. 
 
 See in the almanac the day the moon fulls in September ; by 
 her southing locate her on the Planisphere ; and by bringing her 
 place to the eastern horizon, the time of rising can be seen op- 
 posite the day of the month. Locate the moon for the next day 
 and note the difference in time of rising, to see the Harvest-MooD 
 illustrated. 
 
 TO CONVERT TIME INTO DEGREES, OR DEGREES INTO TIME. 
 
 Bring the. meridian to the center of the star. The degrees of 
 right ascension will be read on the equator or equinoctial opposite 
 on the meridian. The arrow, at March 22d, will point at the 
 hour and minute of R. A., reading from 12 noon around to 12 
 noon, counting 24 hours. 
 
EXPLANATIONS AND PROBLEMS 
 
 EXAMPLE 2. (Page 328.) If it is 12 o'clock at this place, what is the time 
 20 deg. east of us ? Bring the meridian te 20 deg. on the equinoctial, and 
 opposite the arrow read 1 hour 20 minutes past 12. 
 
 EXAMPLE 4. (Page 329.) A vessel leaves Boston, and having been tossed 
 about in foul weather for some days, finds, that when it is 1 2 o'clock by 
 the sun, it is only 11 o'clock and 50 minutes by the watch; is the vessel 
 east or west of Boston ; and how many degrees? Ans. 2 deg. 30m. east. 
 
 TO FIND THE AZIMUTH, AMPLITUDE, ZENITH DISTANCE, AND VERTI- 
 CAL CIRCLE OF A STAR AT ANY TIME. 
 
 Bring the given time to the day of the month ; lay a straight 
 edge on the zenith; let it pass through the star to meet the 
 horizon ; that line will be a quarter of a vertical circle. From 
 the east or west which is nearest to the line, will be the amplitude ; 
 from the horizon to the star, measured on the vertical line, will be 
 the altitude; from the star to the zenith, will be the zenith dis- 
 tance. 
 
 [To measure the azimuth in degrees, we know that a circle is 
 360 cleg.: from N. to S. will be 180 de<r., from S. to E. 90 deg., 
 from S. to S. E. 45 deg., from S. to S. S. E. 22 deg., from S. to 
 S. by E. Hi.] 
 
 TO FIND AT WHAT TIME ANY STAR WILL COME TO THE MERIDIAN, 
 OR RISE, OR SET, ON ANY GIVEN DAY OF THE MONTH. 
 
 Turn the graduated side of the meridian, or the eastern or 
 western horizon, to the center of the star ; opposite the day of 
 the month will be found the time required. 
 
 EXAMPLE. At what time will a Gemini (Castor) culminate, on the 24th 
 of February? (95.) Ans. About 9 o'clock. 
 
 TO FIND ON WHAT DAY OF THE YEAR ANY STAR PASSES THE MERI- 
 DIAN, Oil RISES, OR SETS, AT ANY GIVEN TIME. 
 
 Bring the meridian, or the eastern or western horizon, to the 
 centre of the star ; opposite the given time will be found the day 
 required. 
 
 EXAMPLE On what *lny will a Leo (Reg'-u-lus) be on the meridian about. 
 5 o'clock? (124.) Ana April Gtn. 
 
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