S>^.. \% --.%. IMAGE EVALUATION TEST TARGET (MT-3) 1.0 I.I 1.25 II 1.8 U 1 1.6 * V] '•?# *• ; f ( \ - t .^ ■:fiy ■f/" I i&^^ (:*v' ■'■»»'>!'? \?'J *. B*! •?■*■«' i^ /_i?^ ILLUSTRATIONS^- *»'• - r- i ' \^n'l '*^ ■•> . ^^ I ' ,.?-•- t PREFACE. AsTtioNOMT, confessedly the Mistress and Queen of Sciences, from a Greek derivative, signifying tiie Law of the Stars, is a Science which treats of the motions, periods, magnitudes, eclip- ses, and other phenomena of the heavenly bodies. The fine regions of Asia, the first abodes of mankind, were peculiarly calculated to favour the growth of Astronomy. This sublime Science was much cultivated by the Chaldeans ; the level and extensive plains of Babylonia, the nights passed in the open air, an unbroken horizon, a pure and serene sky, all conspired to engage that nation to cultivate this noble science, to contem- plate the motion of the stars, and to lead them to conjecture on the laws by which they were governed. The Prophet Isaiah, in his usual sublime strain, thus addresses the Inhabitants of the devoted Babylon, — "Will your astrologers, stai'-gazers, and monthly prognosticators, save you from all those evils which are coming on you ! " The upper story of the immense temple of Jupiter Belus, in Babylon, the ruins of which now tower over the plains in inexpressible grandeur, was used as an observatory. Aristotle, the disciple of Plato, and tutor of Alexander, (called the Great,) tried to discover the figure and magnitude of the Earth ; he proved it of a spherical form by its circular shadow on the disc of the Moon, in eclipses. Calisthenes, who attend- ed Alexander to Babylon, found observations for 2,000 years previous to his visit, and sent them to Alexander. Pythagoras taught the true system of the Universe, 500 years B. C. which, after the lapse and errors of many centuries, was revised by Copernicus, and is now settled on the basis of proofs that can never be disturbed ; the only opposition that Copernicus found was from Tycho Brahe, a'celebrated Danish astronomer. His system nearly resembles that of Ptolemy the Egyptian. In de- fence of Tycho it may be stated, that though he adopted an er- roneous theory, he was actuated by pious motives, and that he rendered great service to Astronomy by the correctness and number of his observations. John Kepler was the pupil of Tycho, and a man of a truly original and admirable genius, who, by his great sagaciiy, superior talents and industry, has JiyM .JBBiafSr- nmde discoveries of wliicli no Irnrrs can be found in the on- iiuls of antiquity. Galileo waH conteni])orary with Kepler, and from the resuhn of their united Udjorn, Newton and others were allerwards enabled to estabiisli the most com])lete theories of the Planetary motions. Though Galileo clearly proved the an- nual and diurnal motion of the Earth, his doctrine was declared heretical by an assembly of Cardinals; and though not only vene- able for his years, but excellent m reputation, he was condemn- ed to perpetual incarceration, lor believing anjl divulging truths which strictly accorded with the order of Nature, and which he believed to have been written with the finger of the Almighty. In the year 1(342 he died, after suffering much misery, regretted by the learned and liberal of all Europe. The tribulation in which the great Kepler lived, or rather starved, forms a most painful contrast to the enlinent services he per- formed to science. The pension allotted to him, trivial in it- self, was always in arrear ; and although the three Emperors, whose reigns he adorned, directed their ministers to be more punctual in their payments, the non-payment was a source of continual vexation to Kepler. When he retired to Sagan, in Silesia, to spend the evening of his days, his difficulties became more harassing. Dire necessity, the urgent call of a famishing family, compelled him to apply personally for the ari'ears, and he set out in 1630 for Ratisbon ; but in consequence of the great fatigue which so long a journey on horseback produced, he was seized with typhus fever, of which he died on November 30, 1630, in the 59th year of his age. I have dreaded to in- quire what became of his family after his decease. Such is the usage good and great men too frequently experience in this present evil world. Next on the stage comes an admirable youth, Jeremiah Hor- rox, a celebrated English Astronomer of the 17th century, "the pride and boast of British Astronomy." He was born at Toxteth near Liverpool, in 1619, and educated at Emanuel College, Cambridge ; he began in 1633, in his fourteenth year, to [study Astronomy, and accurately observed the Transit of Venus, No- vember 24, 1639, but died suddenly January 3, 1640, only a few days after he had finished his celebrated treatise, " Venus in Sole visa." His other posthuYnous productions Avere collected and pub- lished by Dr. Wallis, Savilian Professor at Oxford, in 167.3. Hor- rox was the first to predict and to observe the passage of Venus over the Sun's disc, and his theory of Lunar motions aflforded assistance to Newton, who at all times spoke of him as " an ad- mirable genius of the highest order" ; now perhaps not a stone tells where he lies. In 1633 he began to study Astronomy, but the narrow circumstances of this higly gifted young man retard- ed for three years his scientific labours. About the year 16.36, he became acquainted with Mr. Wm. Crabtree, of Manchester, whose' genius led him to the study of Astronomy, with whom t^ ^, ..>-i^ yt .t' t:'i- mM i\'>\,. ..•^>;>. amm "^tttrt^ t Mr. II. corresponded, and they communicated their discoveries to Mr. Foster, Professor of Greshnm College. Mr. If. with the assistance of his friends, who kindly furnished him with books and instruments, now [)ursued his studies with renewed vigour, and applied with great diligence to making celestial observa- tions. Horrox and Crabtree corresponded, — the former at Hool, near Liverpool, England, the latter at Manchester, observed the Transit of Venus, November 24, { old style) 1G39 ; and although Horrox was not aware at the time of the great use that would be made of this important observation, in demonstrating the dis- tance of the Planets from the Sun, and his parralax, yet he made from it many higVily uselul im[)rovements on the Planet Venus. He was also eminently successful in his theory of the Lunar motions. His " Venus in Sole Visa," with his own " Mercu- rius in Sole Visus," were published by Helvetius, at Dantzic, in 1662, and illustrated with notes by that eminent Astronomer. His remaining works, published as before stated, bear the title of " Opera Posthuma." Mr. Horrox, in my judgment, exliibited talents of the highest order, and I have no doubt that had it pleased the Almiglity, in whose hands are the issues of life and death, to prolong his valuable life to the usual age of man, he would have rivalled if not have excelled all his predecessors, and all his successors also, Kepler alone excepted. Next comes the illustrious Newton, in Astronomy a star of the first magnitude, who was born at Woolsthorpe, in Lincoln- shire, six miles south of Grantham, on the 25th of December old style, 1642. His father, Mr. Isaac Newton, died at the early age of 36. Newton was an unusually small infant, his mother said at his birth he might fit in a quart mug ; still he lived to extreme old age, to 85, and never wore spectacles, though so severe a student. Newton when a boy was fond of making sun- dials, clocks, and other pieces of mechanism, and was very stu- dious. On the 7th June, 1660, he entered Trinity College, Cambridge ; the optics of Kepler w-erehis favorite study — the celebrated Dr. Barrow was his tutor. In 1665 he took the de- gree of Bachelor of Arts, and the next year, as the plague broke out, he returned home. The grand object of his studies was to remedy the imperfections of Telescopes. This by great perse- verance he accomplished, leaving to Herschell and to Ramage of Aberdeen, to bring reflecting Telescopes to the greatest per- fection. Newton was knighted by Queen Anne, in 1705, and was held in the highest respect at the court of George I ; the Princess of Wales, Caroline, Queen to George II, a literary la- dy, was delighted with his society, and blessed God that she lived in his days. His manners were pleasing and simple, no trace of pride or ostentation at his great attainments. He was extremely absent, would sit for an hour at his bed side on rising, absorbed in thought, and was in tlie habit of travelling with his hands extended out of each of the windows of his coach, lu 3 Tfe» /:. MUb A lii^JlmmmmiM.. I I i 6 liiri food he wns very temperate, obstcniioiis in the use ofwineH, and Irequently forjjot the time of his mealH till reminded. The celebrated Mr. Locke una his i'riend. Mr. Locke had not a taste for mathematics, therefore he made no progress in practi- cal astronomy. It is pleading to the christian to rank both <^hese great philosophers in the list of believers in Christianity; they both wrote commentaries on certain parts of the Scriptures — Sir Isaac Newton on part of the Prophecies, and Locke on St. Paul's fine Epistle to the Romans, in the exposition of which lie has exhibited his great powers of reasoning and research. Mr. Locke was in every respect an excellent and an exemplai'v christian ; he lived to his 73d year, and had Ins trials and per- secutions in the tyrannical days of Charles II. who would have taken off his head for daring to write on liberty, had he not es- caped to Holland, where he remained till the Revolution. The University of Oxford, complying with the mandate of a corrupt Court, to their eternal disgrace, in November 1C84, at the Kin^^'s express instance, (who died suddenly, Feb. 6, 1G85,) expelled that great philosopher from his lucrative place as Student of Christ Church, whose works have since been their greatest pride and glory ; so are the best men treated, by those who shame- fjlly abuse their power, and are insensible to%nierit. Sir Isaac Newton is supposed to have had little knowledge of the world ; sharpers and swindlers could have cheated him with the greatest ease, had they opportunity. Mr. Conduit, his nephew, says he had a very lively and piercing eye, a comely aspect, with a fine head of hair as white as silver. Bishop At- terbury (in my opinion a much superior judge,) says on the contrary, that the lively eye did not belong to Newton for the last twenty years of his life ; nor was there in his countenance that penetrating sagacity that appears in his writings. He had somewhat rather languid in his look and manner, which did not raise expectation in those who did not know him. He was full of thought (as all learned men are) and spoke little in company. There is a fine bust of him -at Cambridge, and several good j)aintings ; as may be imagined every memorial of so great a man, " an honor and an ornament to human nature," is pre- served, and will be preserved with the greatest care. He died on March 20, 1727 ; his body lay in state, and was interred sumptuously in Westminster Abbey, and though said to be ve- ry liberal he died rich, worth upwards of thirty thousand pounds sterling. To those who desire further information, I refer to his life, lately ptlblished by Sir David Brewster, a work written with great ability and perspicuity. We will now commence our Jaboiu's on Astronomv. ■J i A t\ c1 Ol y ir d ti li V t g >}■.'<■ ». fli ILLUSTRATIONS OF ASTRONOMY. Hx •v^^ (( —So when the Moon, refulgent lamp of night, O'er lieaven'sclenr azuro spreads norsacrea light, When not a breath disturhH the deep serene, And not a cloud o'ercasts the solemn scene ; Around her throne the vivid planets roil, '' And stars unnumbered gild the glowing pole. - ' O'er the dark trees a yellower verdure shed, • And tip with silver every mountain's head ; Then shine the vales ; the rocks in prospect lise ; A flood of glory bu\Ui. <'-oni all the skies ; The conscious swains, rcjuicing in the sight, Eye the blut vault, and bless the useful light." Pope's Homer. ■h # '"b LETTER I. ir Having seen an article in a late pa])er, stating that certain Astronomers in Germany had discovered a colossal edifice in the centre of the Moon — also traces of roads, cultivation, and clear indications of inhabitants in certain latitudes of that Planet or Satellite to our earth ; having taken much pains for many years past, and occupied my time and attention in that most interesting study, I must declare my doubts ofthe truth of these discoveries. SchrsBter, a celebrated German Astronomer, late- ly deceased at an advanced age, occupied much time in inves- tigating the surface or disc of the Moon and Venus. He pub- lished the results of his labours, which were similar to those we now discuss. Had these men brought a few witnesses to their discoveries, we would surely believe them ; this, how- ever, they declined, and for that special reason I dissent. Schrfeter has published a Map of the Moon, in which he notices the height of its mountains ; one named Leibnitz, he makes twenty-five thousand feet high, which is nearly equal to the height of the Himalayan, which divides India from Thibet, the highest on the globe. He also states that he had discovered Twilight in the Moon, her'having an atmosphere being denied by a great majority ofthe best Astronomers of all ages. He al- / '^^ 'fi^ 'r»...t'' J»lM * Wi » 8 ^'f 1. so states his discovery of mountains, five and six fold higher than any on our earth, in the Planets Venus and Mercury. Now we know that Venus has a disc as resplen- dent as a fixed star ;and Dr. the father of Sir John llerschell, tells us, that having examined the disc of Venus and of Mer- cury also, for a series of years, with the best Telescopes, he has never been able to see or observe any inequa- lities on the disc of Venus or of Mercury. He says that the height of the Lunar mountains has been greatly overrated. His discovery of Volcanoes in the Moon, as far back as the year 1789, soon after the completion of his great Telescope, I have no doubt of. Two were in action, ejecting ashes, quite visible, and a third extinct. I am now studying the latest treatise on Astronomy, by the present Sir John Herschell — his valuable work is worthy tho talented son of a celebrated father, who in- dulged in no visionary speculations, but truly told the result of his discoveries. Those amongst the fixed Stars, by the power of his Telescopes, are truly wonderful. V In Chap. 6, Section 362, last Edition of Herschell's Astrono- my, the author says, — " The physical constitution of the Moon is better known to us than that of any other Planet. By the aid of Telescopes we perceive inequalities in her surface, which must be mountains and vallies ; from experiments by the nicro- meter, of the length of the shadows of many of the most con- spicuous, their heights have been calculated — the highest beinfi^ rather under two miles. The existence of such mountains is corroborated by their appearance as small points or islands of light, beyond the extreme edge of the enlightened parts, which are their tops catching the sun beams, and which, as the light advances, at length connect themselves with it, and advance from the outer edge. i* Section 363. " The generality of Lunar mountains present a striking uniformity of aspect; tlieyare wonderfully numerous, occupying by far the greater portion of the surface, and almost universally of an exactly circular or cup-shaped form. They oflTer in its highest perfection the true volcanic character, as may be seen in the Crater of Vesuvius ; and in some of the principal ones, decisive marks of volcanic stratification, arising from de- posits of ejected matter, may be clearly traced witli powerful Telescopes. What is moreover extremely singular in the geo- logy of the Moon, is, that although nothing having the character of Seas can be traced, (for the dusky spots which are common- ly called seas, when closely examined, present appearances in- compatible with the supposition of deep water,) yet on its sur- face are large regions perfectly bare, and apparently of a de- cided alluvial character. The Moon has no clouds, or any other indications of an atmosphere ; were there any it would not fail to be observed in the occultation of stars, and the Phenomena of Solar eclipses — hence its climate must be very extraordina- % >.;'\. 7* v-r •^x^ :-if^ •vg •Vlf I ry ; the alt«^rnations being that ot' unmitigated and burning sun- shine, fiercer than an equatorial noon, continued for a whole fortnight ; and the keenest severity of frost, far exceeding that of our polar winters, for an equal time. The consequence must be absolute aridity below the vertical sun, constant accretion of hoar frost in the opposite region, and perhaps a narrow zone of running water at the borders of the enlightened hemisphere. It is possible then, that the evaporatibn on the one hand, and condensation on the other, may, to a certain extent, preserve an equilibrium of temperature, and mitigate the extreme severity of both climates. Section 365. "A circle of one second in diameter, as seen from the Earth on the surface of the Moon, contains about a square mile. Telescopes must therefore be greatly improved before we could expect to see signs of inhabitants, as manifest- ed by edifices, or by changes on the surface of the soil. Owing to the want of air, however, it seems impossible that any form of life, similar to those on earth, can subsist there ; no appear- ance indicating vegetation, or the slightest variation of surface, which can fairly be ascribed to change of season, can any where be discerned. The lunar summer and winter arise in fact from the rotation of the Moon on its own axis — the period of which rotation is exactly equal to its siderial revolution about the Earth, and is performed in a plane inclined to the Ecliptic, and therefore nearly coincident with her own orbit. This is the cause why we always see the same face of the Moon, and have no knowledge of the other side ; — if there be inhabitants in the Moon, this earth must present to them the extraordinary appearance of a Moon of nearly two degrees in diameter, exhi- biting the same Phases as we see the moon to do, — but irilmo- vably fixed in their sky, while the stars must seem to pass slowly beside and behind it — it will appear cloujded with variable spots, and belted with Equatorial and tropical zones, corresponding to our trade winds ; and it may be doubted whether in their perpe- tual change the outlines of our Continents and Seas can ever be clearly discerned." The diameter of the Moon is 2,180 miles — her distance from the Earth 240,000 miles. Her- schell's great Telescope brings her to within forty miles, as seen by the naked eye. Even suppose that there may be a small degi'ee of atmosphere in the Moon, (if we credit the ob- servations of Schraster,) a man could not long exist there. The late Baron Humboldt, the most scientific of travellers, ascend- ed Chimborazo, one of the highest of the Andes. His ascent was nineteen thousand five hundred feet, the highest point of earth ever trodden by man — the highest pinnacle of the moun- tain was fifteen hundred feet higher, to which an immense chasm, five hundred feet wide, filleiH with snow, hindered the ascent of himself and friends. On that vast height, by reason of the extreme rarity of the air, blood issued from their lips, and TTf %Sfl^ -MU ^N. they ,GouId breathe with great difficulty. An ascent to the Cra- ter of the volcanic mountain Catapaxi, they describe as unat- tainable by any human effijrts. That Volcano, 20,000 feet high, is the highest on earth, vomiting streams of lava and sulphuric flames over the kingdom of Quito — to the destruction of towns and villages, the ravages of which, with the great liability to earthquakes, render a residence in that vicinity no desirable object. r CHAPTER n. The Theories respecting the Moon can only be set at rest by the improvement of Telescopes- — the time may not be very re- mote when we am ascertain the truth. In my humble judgment she has neither animals, or vegetation ; indeed the only kind of proof we have of air in the Moon, is the statement of Schreeter, that he had observed Twilight in her at a certain period. Great credit is due to that ta- lented Astronomer, for his laborious and long continued ob- servations on the Moon and the Planet Venus. The result we shall give, and are concerned to find so much disagreement between his observations and those of Sir William Herschell. Venus and Mercury both ^xhibit Phases like the Moon ; this was foretold by the great Kepler, the improver of the Copemi- can system of Astronomy. Kepler also proved that the motion of the planets was eliptical or oval; before his time they were sup- posed to be circular. That great Philosopher, styled (and just- ly styled) " Illustrious," was rewarded with a small pension by one of the German Princes. The pension was ill paid, he and his family ollan suffer ;d severely, and at length, exhausted by care and poverty, he deceased in the fifty-ninth year of his age, leaving the glory of his name, and that alone, to his family. The Transits of Venus are of rare occurrence, taking place at intervals of 8 and 113 years. They offer the best means of as- certaining the Sun's distance from the Planets, and so impor- tant has this observation appeared to astronomers, that at the last Transit of Venus in 176®, expeditions were fitted out on the most efficient scale, by the British, French, Russian, and other Governments, to the most remote quarters of this Eaith, for the express purpose of obsei*ving the Transit or passage of Ve- nus over the Sun's disc. Under the auspices of George the Third, who patronized Astronomy, the celebrated Capt. Cook sailed to Otaheite for that purpose. The fii'st who ever observ- ed a Transit of Venus was Horrox, a youth of admirable ta- lents, who died in his 22d yeai*, in the reign of Charles X, at the time of the civil wars, afler affording indubitable proofs of his capacity and taste for this sublime science. He constructed Tables of the movements of Venus, proved the exact time of V m'-miiyw^^?'^^ 'm¥ itU ^ he Cra- B unat- 3t high, Iphuric fto'wns ility to 3sirable rest by irery re- humble indeed I, is the light in that ta- iled ob- sult we reement ^rschell. 3U; this ^opemi- I motion ere sup- nd just- ision by le and. sted by his age, family, place at is of as- impor- it at the It on the id other arth, for e of Ve- )rge the )t. Cook observ- able *a- X.at the "a of his structed time of 11 her transit, and wrote a tract of singular ability on the occasion, entitled " Venus in sole visa,** — a tract that has signalized his memory, as much ns Kepler's celebrated treatise on the Planet Mars, has added to the high reputation of that great Astrono^ iner. To the memory of Horrox we may well apply the latter lines of the pathetic address to the shade of Marcellus, by Virgil :— ^ << Hen miserande puer ! li c^uk fata aspera riimpas Tu Marcellus eria. Man:bus date Iilia plenis : Purpureos spargam flores, animamque uepotis His salteiq accuniulem donis, et fungar inani Munere." Ah ! could'st thou break through Fate'd severe decree, A new Marcellus shall arise in thee ! ' Full canisters of fragrant lilies bring, Mixed with the purple roses of the Spring : Let me with funeral flames his body strew,— This gifl which paritnts to their children owe, ) This unavailing gift, at least you may bestow. The Planets Mercury, Venus, Mars, Jupiter, and Saturn, have been known from the first ages of Astronomy. Uranus (in hea- then mythology the father of Saturn,) was discovered by the late Sir William Herschell, in 1781, March 13, in the course of a re^ vievy of the heavens, in which every star visible was brought tinder close examination, when the new Planet was discovered by its disc under a high magnifying power. It has since been ascertained to have been observed on many previous occasions, with Telescopes of insufficient power to isxhibit its disc ; and even entered in catalogues as a star of the sixth magnitude. The discovery of the smaller Planets dates from the first day of the year 1801, when Ceres was discovered by Piazzi, at Pa- Jermo ; soon after Juno, by Professor Harding, at Gottingen ; and Pallas and Vesta, by Dr. Olbers, of Bremen. It was con- jectured by the late Professor Bode, of Berlin, as probable, that a Planet might exist between Mars and Jupiter. Great, howe- ver, was the wonder of Astronomers to find four Planets revolv- ing regularly in ellipses like the greater Planets, round the sun. The force of heat from the Sun's rays, is seven fold as great on Mercury as on the Earth, and on the outermost Planet Uranus 330 times less — the proportion of the extremes being two thou- sand to one. Quitting the region of speculation, we will now see what information the Telescope affords us. Of Mercury we can say little more than that it is round, and exhibits Phases like the Moon. It is too small, and too much immersed in the Sun's rays, to form just observations ; besides, spots are not ob- servable on its disc (though this is doubted,) as on Venus ; its rotation on its axis can hardly be determined ; its real diameter }:i 3,300 miles, its distance from the Sun thirty seven millions of ,-.a; ...An < !•-. \ 12 miles— which will give our readers some idea of the immense distances in our calculations. The diameter of our Earth in 7,900 miles ; that of Venus 100 miles less. Venus is the most difficult of them all to define with Telescopes. The intense lustre of her illuminated part dazzles the sight, and exaggerates the imperfections of Telescopes. Yet we see clearly, that her surface is not mottled over with permanent spots like the Moon, we perceive in it ( in England at least) no mountains, but "a uniform brightness, in which we may at times fancy obscurer parts. It is from observations of this kind, that we may con- clude both Venus and Mercury revolve on their axis in about the same time as our Earth. The most natural conclusion however is, from the very rare appearance and want of per- manency in the spots, that we do not see in the Moon, the real disc or surface of these Planets, but only their atmospheres much loaded with clouds, and which may serve to mitigate the other- wise intense glare of their sunshme. The case is very different with Mars. In this Planet we discern with perfect distinctness the outline of Continents and Seas ; of these the former are dis- tinguished by a ruddy colour, which indicates, no doubt, atmge of ochre in hjs soil ; like what the red sandstone tracts on our earth may ofier to the inhabitants of Mars, but more decided : contrasted with this, by a general law in optics, the seas appear green. This Planet has an atmosphere and clouds, and there appear brilliant white spots at its poles ; these must he snoiv, as they disappear when long exposed to the Sun, and are most visible when first emerging from the long night of his polar winter. Mars has a rotation on his axis ; his real diameter is 4,100 miles. I have seen all these phenomena of Mars, in an achromatic Telescope of ^eat power, at the Observatoiy of Armagh, Ireland, in the winter of the year 1818. . Of all the Planets, Saturn presents us with the most singular^ example, when viewed through a powerful Telescope. He ap-" pears surrounded by a double concentric Ring, separated by a space of nearly 3000 miles, and distant 30,000 miles from the surface of Saturn. The Rings revolve round the Planet at the rate of a thousand miles per minute. These Rings of immense breadth, are only one hundred miles thick. These luminous Rings must afford a magnificent and a brilliant spectacle to the inhabitants of that Planet. During his fifteen years summer the night must be enlivened by the bright reflection of their brilliant arch, extending its luminous curve from tke eastern to the wes- tern horizon, while even during the day the Sun must be ma- terially assisted by its light. — ^There is no Planet in the Solar System, whose firmament will present such a variety of splen- did objects as that of Saturn. The vai-ious aspects of his seven Moons, one rising above the horizon while another is setting ; a third aproaching the meridian, one entering into an eclipse vyhile aaother is emerging from it ; one approaching as a cres- 'V ^ 'i :%■ i ^k mmense Earth ia the most ! intense iggerates that her lie Moon, IS, but a obscurer nay con- in about onclusion nt of per- ,the real jres much ;he other- f different ctnessthe are dis- ibt,atinge ;ts on our decided : ;as appear and there e arww, as I are most his polar iameter is [ars, in an rvatory of 3t singular, e. Heap- rated by a 3 from the met at the f immense luminous acle to the immer the )ir brilliant to the wes- ust be ma- the Solar y of splen- f his seven is setting ; an eclipse as a cres- 13 ' • V cent, and another gibbous ; and sometimes all of them shining together in one bright assembly; the majestic motion of the rings, at one time illuminating the sky with their splendour, and even eclipsing the stars, — at another time casting a deep shade over certain portions of the Planet, and opening to view the wonders of the starry firmament, are scenes worthy of the ma- jesty of the Almighty Creator to unfold, and of his creatures to contemplate, and to fill their hearts with devout gratitude and praise for his wondrous works. The elder Herschell has been very fortunate in his observations of Saturn ; he gives all the dimensions of the Planet and of his Rings. — It is certainly the most wonderful object in our Solar System. In the event of the perfection of Telescopes, we will know much more of his Moons, and those of Jupiter, four in number, and highly inte- resting also. In reference to the immense size of those Pla- nets, all the Moons are required, while one is sufficient to light our smaller Planet. Though certain German Astronomers pr^- tend they have observed a Moon to Venus, on the closest obser- vations by the best Astronomers, with the most powerful Tel- escopes, none has been seen either in its place in her firma- ment, or accompanying her on her Transit over the Sun's disc. The opinions of Kepler, Horrox, Herschell, and Schreeter, are, that she has no Moon, nor have Mercury or Mars. How the absence of Moons may be remedied, we know not. LETTER III. Omitting a description of the extra Zodiacal Planets, Juno, Ceres, Pallas and Vesta, until we shall arrive at the observa- tions of Schreeter and Herschell on them, we now proceed to Jupiter, the largest of the Planets, generally su])posed ninety- four thousand miles in diameter — stated by Sir Wm. Herschell, at eighty-seven thousand, by Brewster at eighty-two thousand ; even the lowest computation, (the last,) would prove Jupiter's diameter to that of the Earth, as upwards of one thousand to one. Jupiter has four Moons or Satellites, frequently eclipsed ; the third (the largest,) 3,377 miles in diameter, larger by 1,177 inUes than our JVfoon ; the fourth 2,890 miles in diameter ; the first and second are less, but as large as our Moon, each ex- ceeding two thousand miles in diameter. These may well be imagined veiy magnificent objects, and highly useful to the in- .habitants of that stupendous globe. The disc of Jupiter is al- ways observed to be crossed in one direction by dark band« or belts ; these belts present dissimilar aspects at divers times — they vary in .breadth and situation on the Planet's disc, though never in their general direction ; they have even been observed broken up, and distributed over the entire face of the Planet— B .^ IP** < •-. 4 « 1 ^^ '¥ mk w '^;«i 'yjn* i"! > . ;■!* '% but this is rare. Dark spots like clouds are also seen ; and from close observation of those spots, with glasses of the high-> est powers, it is concluded that Jupiter revolves on his axis in the surprisingly shoi*t period often hours, (less by five minutes) on an axis pei*pendiculai' to the direction of his belts. That it is the dai'k body of the Planet that appears in these belts, is evident from this, that they do not come up in all their strength to the edge of the disc, but fade away gradually before they reach it. — His Moons offer a visible disc with good telescopes. Schrseter doubts our ever having exposed to view the disc of Jupiter — like the Sun he remains covered with a hazy atmos- phere which intercepts our view. I have referred in my last Letter to Saturn, to which Planet the late Sir William Herschell directed much laborious atten- tion for a series of years, and imjjroved in a great degree our knowledge f that singular Planet. — Saturn is allowed to be seventy-nine (some astronomers make him eighty-nine) thou- sand miles in diameter, nearly one thousand fold exceeding our Earth in bulk — one-eighth only of the density of Dur Eartib— less dense than Jupiter. This immense globe, besides b^g attended by seven Satellites or Moons, is surrounded with turo broad, flat, extremely thin rings, concentric with the Plabbet and each other, both lying in one plane. Saturn has also belts like Jupiter. I observed these belts or clouds, five of stfren Satellites, and the double rings distinctly visible ; also the lour magnificent Moons of Jupiter, (the discovery of which by Gali- leo was the first fruits of the Telescope) at the Observatory of Armagh, Ireland, in the winter of 1818, where I passed six weeks making obsei^vations, assisted by the best achromatic telescopes imported from Germany. That the Ring is a solid opaque substance is evident, by its casting its shadow on the body of the Planet, on the side nearest the sun. Dark spots* are also apparent at intervals, which closely observed with powerful Telescopes, like the spots on Mars, Jupiter and Ve- nus, indicate the rotation of Saturn on his axis in ten hours and twenty-nine minutes. It may very naturally be asked, how so stupendous an arch, ifcomposed of solid materials, can be sus- tained without falling in upon the Planet. The reply will be found in the swift rotation of the Ring in its own plane, which close observation has detected, owing to certain portions of the Ring being less bright than others. It is the centrifugal force, arising from this rotation, that sustains the Ring. The Rings of Saturn must present a most magnificent spectacle from those regions of the Planet which lie above their enlightened sides, as vast arches spanning the sky, and holding an invari- able situation amongst the Stars. On the other hand, in the regions beneath the dark side, a solar eclipse of fifteen years in duration, must aftbrd (as we suppose) an inhogpitable asylum to animated beings ; ill compensated by the faint light of the Ah ■Wwi M^' '^ en; and the high-> is axis in minutes) That it I belts, is strength fore they lescopes. e disc of jy atmos- , 3h Planet »us atten- egree our i^ed to be ine) thou- eding our r Earth— lesb«lng withtwtJ he Placet also belts of swcn [) the four i by Gali- •vatopy of assed six :hromatic is a solid w on the ark spots ' ved with r and Ve- lours and J, how so n be sus- y will be le, which msof the gal force, he Rings icle from ightened invavi- |d, in the en years le asylum ht of the Satellites. But wo cannot ju^_ "".M.^,. /).;?•■ 1 17 ised by tlic 7S Sir John I ease sixty eaped one light exist, the biioy- ht there be though not tmosphere, d becomes r apparent- is free from It appears 8 an atndos- ion in her Vesta is a ) in a clear pure and i — it is not its disc. It telescopes urately dis- the circum- , eye proves 3. Having system, the iie smaller n Satellite, discovery pains and or Inodern. mountains ear the ho- le ss, or ad- mountains e presume tn, and thus le has also slongcon- lins exceed more like- ear and un- he planets. I cannot mus being 10 and 11 ifCbimbo- ;he second but I am also confident that Schrrcter, the first practical astronomer of his time, would not assert a wilful fulseliood. We ai*e bound to use the reason that God Jias given us, and not be led by fan- cy even in those sublime but occult discussions. Schrceterand Tobias Meyer, (both Germans,) have given a catalogue of up- wards of four hundred districts; of the Moon, all named, as are the principal mountains and vallies also in that Satellite. In my first Letter I observed that the mountains in the Moon were very numerous, occupying the greater portion of her sur- face. Herschell and Schrseter both agree that water in any quantity does not exist in the Moon, nor am I at all inclined to imagine she has an atmosphere of much density, or is inhabit- ed. Sir John Herschell was sent (in 1832) at the expense and by order of our government, to make observations on the fixed stars apparent hi our most southern latitudes. For this purpose he repaired some years ago to the Cape of Good Hope, with a complete astronomical apparatus. Though I have anxiously sought an account of him or of his labours, I can find none. The Emperor of Russia has ordered an observatory to be erected at Dorpat in Russia, where Professor Struve now dwells ; and the German opticians, the best in Europe, are vying witb each other in the construction of telescopes. If they succeed, we will soon learn the real state of the Lunar the- nomona, where improvements in our knowledge of astronomy must commence. The immense range of mountains, and the insulated hills that mark the surface of the Moon, have evident- ly no analogy with those on our own globe ; they bear, how- ever, a stronger resemblance to the towering sublimity and ter- rific grandeur of the Alps, and to their ruggedness, than to the tamer irregularities of less elevated regions ; huge masses of rock rise at once from the plains, and elevate their peaked summits to an immense height in the air, while projecting crags spring from their rugged fianks, and threatening the vallies below, seem to bid defiance to the laws of gravitation. Around the base of those frightful regions, are strewed nume- rous loose and unconnected fragments, which time seems to have detached from the parent mass ; and when Ave examine the ravines which accompany the overhanging cliflTs, we expect to see them torn from their base, and that the process of des- tructive separation is about to be exhibited in tremendous re- ality. The strata of Lunar mountains called the Appenines, which traverse a portion of her disc, arise with a precipitous and craggy point from the " JWare /m&riwn ;" in some places their elevation exceeds four miles. The analogy between the Earth and Moon fails in a more remarkable degree, when we examine the circular cavities that a])pear in every part of her disc ; some of the immense cavities are four miles deep and forty in diameter. A high annual ridge marked with lofty peaks and little cavities general I v encircle them, — an insulated b3 ,'.■.-' I. • •'•'I'l » •i 18 niomitain frequently riscsj in their centre; these hollows are most numerous in the South West paj-t of the Moon — hence its peculiar brillianc}'. The ridges which encircle the cavities reflect the most light, and appear near the time of full Moon like a number of brilliant radiations issuing from the lai'ge spot called Tycho. We will still continue the subject of the new discoveries in the Moon, as the most interesting to us from its proximity — and from the high scientific character of the Astronomer Sclreeter. LETTER V. Of Ctesiphon, (on the Tigris,) the renowned City of the Par- thian Kings, it is reported by all travellers, that not a blade of grass, suflicient to cover the smallest insect under heaven, or a drop of water to allay its thirsty is now visible on the site of its immense riiins. I am of opinion, that when human art here- after, and probably at no distant time, shall have improved te- lescopes to the highest perfection, that the Moon will exhibit the like or similar scenes of devastation and aridity. By per- sons uninformed in science, it is wondered at and even doubt- ed, that our Moon is generally of an aspect so very mountainous and broken. To this we reply, that her surface is admirably fitted by her Divine Author for the reception of and the trans- mission of the Sun's light to our earth ; were her surface smooth she could neither receive nor reflect light, and it is highly probable that at a future period the Moons of Jupiter, of Saturn, and of Uranus, will be found in geological construc- tion, very similar to our useful Satellite. Schrseter admits the rarity of the Moon's atmosphere, — that of the Earth he states to be forty-five miles — the Moon's only fifteen hundred feet in height. In explanation of the Lunar caverns, it is difiicult to explain the formation of these immen&e cavities ; but we think our Earth would assume the same figure, if all the seas and lakes were removed ; it is therefore probable that the Lunar cavities were either intended for the reception of water, or that they are the beds of seas or lakes, that have formerly existed in tlie Moon. There being no water apparent is a strong confirma- tion of this theory. The deep caverns which appear in almost all parts of the Moon's surface, have' induced many astronomers to believe that they have a volcanic origin. This opinion first maintained hy the learned Hook, was supported by others and opposed by few. Many astronomers have observed the pro- gress of volcanoes before Herschell had formed his great re- flector. This Telescope, formerly forty feet in length, has been altered, and the glasses are now inserted in tubes of twenty glfmt ^^^ iBir-''T'S^ 19 / feet, iIjc former having been found by experience, extremely Hifiiciilt to manase, as frequently the delay of one minute de- feats the object of a celestial observation. HerschelPs obsei*va- tory still re^nains at Slough, near Windsor, (England.) The observatory of the learned Schrreter, at Lilienthal, near Bre- men, (Germany,) was destroyed by the French in the German wars. Philip the Second, on the loss of his armada, by tem- pests, said that " We did not wage war with the elements ;" — this was nobly expressed. We would imagine the French the last nation of Europe who would destroy an Obsei'vatory, and thus wage war with the sciences. Such are the terri^'le evils of war, ever deprecated by good men. - To continue on the Moon. — On May 4, 1783, Dr. Kerschell saw a luminous point in the obscure part of the Moon, and two mountains. In 1787 he saw similar objects, which we will des- cribe in his own words. " On 19th April, 1787, I obseiTed three volcanoes in different places of the dark part of the new Moon. Two are nearly extuict, or ready to break out, which may be decided next lunation ; the third shows an active erup- tion of fire or luminous matter ; I measured the distance of the crater from the northern edge of the moon — its light is much brighter than the comet discovered at Paris the 10th of this month. April 20th, 1787. — The volcano burns with greater vi- olence than last night ; I believe its diameter cannot be less than 3 deg. by comparing it with Uranus. As Jupiter was near I turned the telescope to his tiiird Satellite, and estimated the diameter of the burning part of the volcano to be equal to at least twice that of the Satellite, (three miles in diameter.) The figure is irregular and round, sharply defined on the edges. The other two volcanoes are much further towards the centre of the Moon ; no well defined luminous spot can be observed in them. The three burning spots are plainly to be distinguished from the rest of the marks on the Moon, for the reflection of the sun's rays from the earth, is, in its present situation, sufficiently bright with a ten feet reflector, to show the Moon's spots, even the darkest of them. Nor did I perceive any similar phenomena last lunation. The appearance of what I have called the actual fire or* eruption of a volcano, exactly resembled a small piece of burning charcoal, when covered with a very thin coat of white ashes, wliich frequently adhere to it when it has been some time ignited ; and it had a degree of brightness about as strong as that with which such a coal would be seen to glow, in faint daylight. All the afljaceht parts of the volcanic moun- tain seemed to be faintly illuminated by the eruption, and were more obscure as they lay at a greater distance from the crater. This eruption resembles much what I saw in May, 1783, an ac- count of which I will communicate to the Society. It differed much, however, in magnitude and brightness ; for the former volcano, though much brighter than that now burning, was not ''<■' ;•-', X'-€i MjHSm i^ UQ I 1 . large in tlio diincriHioiiH of its eruption. The fonnci* seen in tlio telescope rcHcnibled a Htar of the 4th nmgnitiule, a8 it nn- |)cars to the natural eye. TImh, on the contrary, hIiowh a viHiblo disc of luminous matter, very different from the sparkling brightnesH of 8tar light." Hero his obHcrvutions on volcanoes end. Dr. Olbcrs, of Bremen, (Germany,] discovered two craters, which were wanting in Hchra^ter's cliarts, \^ho had frequently examined this section of the moon under favorable angles ofil- lumination, but had never seen a trace of those craters. He, however, found them ; they were very deep, and surrounded by an elevation of little brightness. The existence ofa lunar atmosphere has long been a disputed point. The constant serenity of the Moon's surface, undis- turbed by clouds, induced astronomers to believe that she could not have an atmosphere, and this oi)inion was signally con- firmed by the brilliancy of light retained by the fixed stars and ])lanets, when nearly in contact with the limb of the Moon, and when their light must have passed through her atmosphere. M. de Fouchy, in a memoir on this subject, endeavors to show that the duration ofecli])ses and occultations ought to be dimi- nished by the refractive power of the Moon's atmosphere. In the eclipse of the sun which occurred in 1724, total darkness continued two hours sixteen minutes, which De Fouchy con- tends would never have happened had the Moon even the rarest atmosphere. On the other side, the aspect of the Moon's' limb in total and partial eclipses of the Sun, has suggested ar- guments for a lunar atmosphere. In the year 1605, Kepler perceived that the Moon in a solar eclipse was surrounded with a luminous ring, most brilliant on the side nearest the Moon. The same was observed by Wolf the very next year. At Geneva a luminous ring was seen round the Moon. In a total eclipse of 1745, Dr. Halley observed a diminution of light in the limb of the Sun which was emerging before total dark- ness. The appearance also of the stars and planets when eclipsed by the Moon, furnish us with additional proofs ofa lunar atmosphere. In the occultation of Saturn, observed June 17, 17G3, the ring and the body of Saturn appeared effect- ed by the proximity of the Moon, and resembled a comet at the moment of emersion. Mr. Schreeter (so oflen mentioned with great respect in these letters) had perceived that the high ridges of the mountains Leibnitz and Doverfell — the former he computes twenty-five thousand feet in height, (nearly five miles,) were less illuminated than the other parts of the Moon's disc. He also observed several obscurations and returning serenity, eruptions and other changes in the Moon's atmosphere, from which he was led to expect that a faint twilight might be per- ceived towards her cusps (as was the case from his observations on Venus.) The occultation of Jupiter, April 7, 1792, was ob- oi ell ht l>i| or S.r-'nrr; l^\'- ■ « . ^_^ mMam M^ ■'T^^ Ncen in iH it nn- [i viHible ixirkliiig )lcanoc8 craters, jquently ;leH of il- l's. He, rounded ilisputcd ;, undis- lie could illy con- itars and oon, and osphere. to show be dimi- lere. In [larkness chy con- Bven the Moon's sted ar- Kepler Irounded irest the !Xt year, fn. In a of light lal dark- :s when lofs of a >bserved Hffect- komet at [ntioned [he high rmer he 1 miles,) h's disc, [erenity, re, from Ibe per- Vvations Was ob- n xcrvrd alno by him — some of the Satellites became indistinct on the lin)b of the Moon, while others remained uuobscurcd-r- the bcltH »nd Hpots of Jupiter also appeared very distinct, when close to the limb of the Moon. These observations, however, have failed to convince nie of the existence of a lunar atmos- phere of any great density or extent. LETTER VI. i't" \ As some of my friends have expressed doubts 6f the certainty / of my opinions concerning the geological construction of our \ Moon, certain German Astronomers having stated their obser- I vation of Roads, Buildings, and so forth, in that secondary P}a-> net, it was to conflite these tntii that I first coirunenced the subject ; and though I trust I liave fully confuted them to the satisfaction of the majority of my readers, by further research and enquiry I am happy now to be able to set the matter totally at rest, by the testimony of eije iidtnesseSf now. resident in Hali- fax, who have enjoyed the high privilege and gi^tification of observing the Moon and all parts of her disc, at various times, through the famous reflecting telescoj)e of the lute Mr. Raniage, of Aberdeen, N. B. Schrreter, Herschell and Laplace, all agree that the atmosphere is of the rarest kind, such as may exist in the half exhausted receiver ofan air pump. Who could dwell in such a climate ? No man could exist there. No ap])earancc indicating vegetation can anywhere be observed ; there is there- fore no change pf season. Two eye witnesses, now in Halifax, agree in stating that the asjiect of the moon is frightful in the extreme — immense rocks projecting over the pits with which her entire surface is covered. How could roads be formed through the midst of the Trosacks of Perthshire, (a rocky re- gion); or through the rocky mountains of Norway or Switzer- land. The frequent occurrence of deep pits, would, however, ^ utterly prevent the formation of roads, though with great labor and expense roads might be and have been cut, even through rocks. Herschell, to prove the existence of burning mountains, • says " successive deposits of ejected matter, (lava) can be clear- ly traced with powerful telescopes." Mr. C. to whom I spoke, and closely questioned on this subject, said he could prove he had seen immense heaps of dark lava, which evidently had been burnt and ejected. The rocks which fell from the moun- tains were scattered — broken in fragments at their bases ; the ' lava ejected by the action of volcanoes was generally cast on ridges of the mountains, or on projecting crags. The rocks, he stated, had the appearance of Peterhead granite, or of the iron stone on the road near Fresh Water. There appeared no fire, ^ or even smoke in the moon, at the time of his observations ; If" wmmm'^iim- wmm m iV- , i ■:^^>; :m*' ■A.<:i' m'.-\ '^.''■::'j. S2 \ iH t)ut there was decisive evidence in the colour of the rocks, that they had withstood the action of intense heat, which probably split these rocks, and caused them to fall into the hollows from the parent mass. I say in candour I mode no such observation of the moon— the telescopes I used were not at all to be com- pared to those of Ramage. To my question to Mr. C. whether he observed any where on her disc any traces of vegetation, or any appearance of water, lakes, or rivers, he states thatnothing of the kind appeared ; his expression was strong, viz., that on the entire disc of the moon, there was not as much g^ass or vegetable matter of any kind, as would either hide or feed a squirrel. I believe the man's testimonj^, delivered as well be- fore as after I had read to hiiji my obseivations, to be perfectly true, and conclusive on this, to me, highly interesting enquiry* I am rejoiced to find my theory thus amply supported by de- cisive proof. On the subject of the Moon I have labored hard, having written lour letters, and this a fifth ; so useftil, so very interesting is that fine planet to our earth. The moons are all alike—none of them are inhabited, noi* is it at all probable that the more minute planets are inhabited. Helvetius, a German, who published the works of our admirable Horrox, was the first, Ricciolus the second, who published in the 17th centuiy charts of the Moon, — the execution was coarse and erroneous, teles- copes were imperfect and micrometers still more so. The best maps of the Moon have been constructed by Russel on a magnificent scale ; these plates, from their great size and cost, are excluded from works on Astronomy. We are highly gi*a- tified by this fine and elaborate delineation of the Moon, but the astronomer will find in Mr. Blunt's maps, many variations, perhaps more consistent with practical observation, and with the actual view the moon presents in telescopes in common use. Blunt, and other able engravei's, considered the moon in the Ught of a calx or. cinder. It is obvious that such must be the condition of the moon, so constantly subject to the earth's ac- tion; for if water to any extent existed on the Moon's surface, her tides would be at least 64 feet higher than those in our seas. We are certain that no water has been discovered, even with the powerful telescopes of Herschel orRamage; therefore the moon with the rarest atmosphere and no water, cannot possi- bly be inhabited ; and if volcanoes have been observed, (one measured by Herschcll three miles, which m :st have been many volcanoes burning at one and the same time,) these afford proof that the medium of space in which the moon is immersed, is itself a suj)portcr of combustion. Meteoric stones found on various parts of our earth are generally supposed to have been cast out of volcanoes in the Moon, past the limits of her attraction, and have fallen within the attraction of our Earth. Schrajter once imagined heliad discovered a great ci- ty near Marius, but afterwards examining the spot with still t 'V ^: rta 23 ks, that robably v» from irvation je coni- vhether Ltion, 01" nothing that on gVass or r feed a well be- jerfectly enquiry, d by de- ed hard, so very IS are all able that German, the first, ly charts us, teles- so. The ssel on a and cost, ;hly gi-a- i,but the riations, land with common moon in istbethe irth's ac- surface, our seas, sven with ifore the t possi- fcA, (one ive been le,) these moon is ric stones )posed to limits of n of our great ci- kvith still more powerful telescopes, he found his supposed city to con- sist of a vast and confused mass of granite, broken and scatter- ed in various directions. Ricciolus calculated the highest mountain in the moon at nine miles, (Mount St. Catherine) pro- bably the Leibneitz of Schrueter,^ which that great aGtronomer accurately measured in the close of the last century with the most approved instruments, and found to be only half that ela- vation, namely, four miles and three quarters English mea- sure. This, positively, is the highest of the lunar mountains. The Appenines, so called, range from two to four miles in height. All the lunar mountains are not volcanic, but all are rocky, indeed frightfully so. The dislodgement of immense masses of rock is not peculiar to the Moon. The celebrated road over the Simplon through the Alps, from Geneva to Mi- lan, constructed by the Emperor Napoleon at an expendi- ture of eight millions of English pounds, is often totally blocked up by the fail of immense masses of rock. The distance is sixty miles. — Tunnels are cut in some places for six hundred yards in length, tiirough one strata of solid granite. It is a gigantic and stupendous work, now used only for mili- tary purposes. The writer commenced the study of Astronomy in his fifteenth year, at the University of Dublin ; the work then in use was written by Dr. John Kiel of Oxford — it was entirely scientific — no elevation of language. In a work of from three to four hundred pages octavo, a small proportion only can be comprehended by a reader not conversant with mathema- tics. As many improvements had been made and new disco- veries in the Moon and Planets generally, (exclusive of Her- schell's grand discoveries amongst the fixed stars,^ Dr. Brink- ley was directed by the Provost and senior fellows of Trinity College, Dublin, to prepare a new work on this noble science. The expectations raised by the high reputation of our learned Professor were not realised. This work was also quite too scientific for young astronomers. Bonnycastle's was my fa- vourite study, and it was generally expected by my friends in the university, that from my admiration, taste, and warm feel- ings in pursuit of the knowledge of this noble science, in the course of time, I would have arrived at a high degree of pro- ficiency. My unfortunatL expedition to North America has re- tarded that feeling, which I hope to recommence on my return to Europe. LETTER VII. ' Having given in those Letters the most satisfactory account of the Planets iu general, and of the Moon in particular, that we could possibly collect, we will observe that there is no Science ■,^:.:,*^ ;^ , ■■ -. ^ ■»- — ~^-^ — -^-" />J ^ '-^ ,^;-*«,^> sv^ M -^i ^y: /-4^:iV:.■■■.,^'p'!^W ■servation, and with what appears to every one, until he has un- derstood and weighed the proofs to the contrary, the most po- sitive evidence of his senses ; thus the earth on which he stands, which has served for ages as the unshaken foundation of the firmest structures, either of art or nature, is divested by the As- tronomer of its attribute offixety, and conceived by him as turn- ing swiftly on its axis, and at the same time moving onwards through space with great rapidity. The Sun and the Moon, which appear to the uneducated round bodies of no very con- siderable size, become enlarged by the Astronomer into vast globes. The Moon, 2,180 miles in diameter, and the Sun im- mensely larger ; the Planets, which appear like stars somewhat brighter than the rest, — are to the Astronomer, spacious, elabo- rate, and habitable worlds, some of them vastly greater, and far more curiously furnished than the Earth, as there are also x)thers less so ; and the Fixed Stars, which present only lucid sparks asd brilliant atoms, are to him Suns of transcendant glory, — so that when, after dilating his thoughts to compre- hend the grandeur of those ideas his calculations have called up, and exhausting his imagination and the powers of his language to devise similies and metaphors illustrative of the immensity of the scale on which his universe is constructed ; he shrinks, back into his native sphere, he finds it in comparison a mere point, so lost even in the minute system to which it belongs, as to be invisible and unsuspected from some of its principal and remoter members. The object of these letters, strictly didactic, is simply to teach what we have known heretofore by celestial observation, and .what we have since acquired by reading and reflection.- The moderate limits of twelve letters, and the necessity «f every point being treated on, within that limit rather diffuse in expla- nation, (for instance our notices of the Moon,) as also the emi- nently matured and ascertained character of the science itself, render this course both practicable and eligible ; as there is no danger, at this advanced period of the science, of any revolution in astronomy, like those which are daily changing the features of the less advanced sciences, calculated to destroy our hypo- theses, and to confuse our statements. Writing only to be un- derstood, and to communicate as much information in as little space as possible (as in our Letters on Prophecy) we can afford to make no sacrifices, to system, to form, or to anectation. We now proceed to discuss the subject of Comets, one of which has visited us this season ; and of whose visit we have direct evidence in the length and severity of our winter, all over this earth. Previous to our commencing a discussion on Co- mets we will offer some obsei*vations. The work on Astrono- [,-r '^^ Mmmmi jf/HtlK^r ;w&^, ;*♦!*: mess to ns stand ilgar ob- ! has un- most po- e stands, n of the y the As- n as turn- onwards le Moon, very con- into vast 3 Sun im- jomewhat lus, elabo- er, and far B are also ., only lucid nscendant ) compre- calledup, 3 language immensity he shrinks m a mere lelongs, as acipal and ly to teach ation, and ion. The of every inexpla- |o the emi- nce itself, ;here is no revolution le features our hypo- to be un- in as little can afford [ation. Its, one of we have ;er, all over Ion on Co- Astrono- my by Sir John, son to the late Sir William (or Dr.) Herschell, displays much ability and knowledge oi' the science. He omite not to mention all his father's observations and their results ; but he is not equally just to the merits ol' other eminent astro* nomers. Schrseterhe mentions once only (I believe) and that incidentally ; and of Horrox he makes souje slight mention, (in a note) as an honor and an ornament to astronomy, though he had a fair opportunity in describing Venus and her Transits. Kepler he justly styles Illustrious — his tame is everlasting. His father, though surveying the heavens with his powerful te- lescopes, from 1780 to J801, never discovered the lour minor Planets, or eVen 8usf)ected them, lying between the orbits of Mars and Jupiter. Nor did Schrceter discover any of them. The theory (l believe invented by Herschell,) that these were the broken parts of a great Planet destroyed by an explosion, was and is quite too absurd to he credited. Herschell was evi- dently jealous of their discovery by others, and labours hard to make them as insignificant as possible. He says one of the largest of them does not exceed in size a Scotch estate (80 miles.) My opinion is, that if they were so diminutive, they would require telescopes such as have not yet been invented by the art of man ; and Schrseter, in my judgment, fairly -ac- counts for the errors of Herschell in their diameter. The suc- cess of his observations on Saturn, on his double concentric ring — on his moons, particularly his discovery of the two inte- rior (on the edge of the ring) prove the great power of his teles- copes — as still more decidedly his discoveries among the fixed stars and nebulaB. Honor we are disposed to give where ho^ nor is justly due. Herschell has also observed and notices the retrograde movements of the two Satellites of Uranus, contra- ry to the laws of Kepler, which his son, (by observation) con- j^rms ; they move from east to west. Equal in ability to any of the jpresent race of astronomers is a female, Mrs. Somerville. Her icorrespondence with Laplace, whose work " Mcchanique Ce- Peste," is next in credit to Newton's Principia, and her own ori- Iginal works (the latest of which she dedicated to the Queen of p^ngland,) prove her superior capacity and acquaintance with latiiematics, a perfect knowledge of which, and of trigonome- :ry in particular, are indispensible to the practical astronomer. '*i8S Herschell was also much celebrated for her acquirements. We proceed from this digression to the subject of Comets, 'heir extraordinary aspects, their rapid and apparently very •regular motions, the unexpected manner in which they oflen urst upon us, and the imposing magnitudes which they at tJfi mes assume, have in all ages rendered them objects of asto- jlishment, not immixed with superstitious dread to the igno- fant, and a complete enigma to those conversant with the won- 1ers of creation. No rational account of their Tails (so called) 18 ever been given In a list cited by a celebrated French as- c w^ tmmm 28 tronomer (Lalande,) 700 comets are noted — their actual num- ber are many thousands. Many indeed must escape observa- tion by reason of their courses, traversing only that part of the heavens above the horizon in the day time ; such comets are seldom visible in a total eclipse of the sun, one of which hap- pened, by Pliny's account, sixty years before Christ, when a large Comet was actually observed near the stin. Several have been seen even in the daytime. That feelings of awe and as- tonishment should be excited by the sudden appearance of a great Comet, is not surprising, being the most brilliant and.im- posing of all the natural phenomena. Comets consist of a large and splendid, but ill defined nebulous mass of light, called the head, which is usually brighter towards its centre, and ap- pears of a vivid nucleus like a star or planet. From the head appear to diverge two streams of light, which grow more dif- fused at a distance from the head, and which sometimes close in and unite at a little distance behind it, sometimes continue distant for a great part of their course, producing an effect like the trains left by some bright meteors, or like the diverging fire of a sky-rocket, without sparks or perceptible motion — this is the Tail. This magnificent appendage attains occasionally an immense apparent length. The Comet of 1680, the most celebrated of modern rimes, was the most remarkable of all, with a head not exceeding in brightness a star of the second magnitude. I, VI LETTER VIU. The great Comet of 1680, referred to in my last letter, cover- ed with its Tail an extent of more than seventy degrees of the heavens, or as some state ninety. The Tail is by no means an invariable appendage to Comets ; many of the brightest have short and feeble tails, and many more want them totally. Cas- sini describes the Comet of 1682 as being as round and as bright as Jupiter. Some Comets still have many tails, or streams ol' diverging light ; that of 1744 had six »ails, spread out like an immense fan, extending to a distance of nearly 30 degrees in length. The mob. unsubstantial clouds which float in the high- est regions of our atmosphere, and seen at sunset to be drench- ed in light, must be considered as dense and massive bodies, compared with the filmy texture of a Comet. Accordingly, whenever observed with powerful Telescopes, v/e dispel thf illusion which gives solidity to the head, though it is also true that, in some, a very minute stellar point has been seen, indi- cating the existence of a solid body. We now come to speak of the motions of Comets ; these are irregular and capricious, — sometimes they remain in sight on- Kl <' ;H^f,Ti al nutn- Dbservft- •t of the nets arc ich hap- ;, when a eralhave 5 and as- ance of a it andim- isist of a Tilt, called !, and ap- the head more dif- imes close s continue effect like diverging otion— this ccasionally 0, the most ;able of all, the second tter, cover- rees of the o means an ghtest havo tally. Cas- nd as bright streams ol out like au degrees in in the high- >be drench- —Jisive bodies, Accordingly e dispel the is also true seen, indi- ; these are in sight on- ly a few days, at other times for many months ; some move with extreme slowness, others with immense velocity. The great Comet of 1472, described an arch in tJie heavens, of 120 degrees in extent, in a single day. They do not confine them- selves like the Planets, to a certain region of the Heavens, but traverse every part ; their variations in apparent size, during the time they continue visible, are no less remarkable than those of their velocity ; their tails increase in length and brightness till they approach the Sun, and are lost in his beams. After a time they again emerge on the other side, receding from the Sun with a velocity first rapid, but gradually decaying. It is after passing the Sun, and not till then, that they shine forth in all their splendor, and their tails acquire the greatest length, thus plainly indicating the action of the Sun's rays as the ex- citing cause of that emanation. As they continue to recede Irom the Sun their motion diminishes, and the tail dies away. Without the clue furnished by the theory of gravitation, the enigma of these irregular movements might have remained for ever unresolved. Recently two Comets have been identified as having performed several revolutions about the Sun. The first of these is called from Professor Encke, of Berlin, who first ascertained its periodical return. From the Elipse calcu- lated by Encke, (in 1819,) its' return in 1822 was predicted by him, and observed in New South Wales by Mr. Rumken, being invisible in Europe. Its next return was in 1835, {as we have witnessed.) The other Comet lately discovered, is that of Biela, who first noticed it. Its last appearance took place in 1832, — the next will be in 1838. It is a very small Comet, without a tail, its orbit, by a remarkable coincidence, very nearly intersects that of the Earth, and had the Earth, at the time of this Comet's passage in 1832, been one month in ad- vance of its actual ])lace in the heavens, it would have passed through the Couict, which probably would be attended with danger. as fully as our limits will admit of, the we next proceed to consider the Fixed bodies we have described, the Heavens innumr-able multitude of other objects, which are called Stars. Tiie aspect of the Firmament, as it appears to the naked eye, is calculated alike to excite curiosity «^ and admiration ; but when we ascertain that the solid contents of the Sun exceed that of our Globe above a million of times, • and that its distance from us is immense, namely, ninety-five 4 millions of miles, (Hcrschell supposes the Sun an inhabitetl fAvorld,) the mind becomes overjrowered, and seeks in vain to •^discover anything like an adetpiate solid of such magnitude oi' |. matter, and of quantities of space. Many of the Fixed Stars ^ being Suns, dis[>ensing light and heat to other countless worlds, * classing our Sun with the Stars is just analogy. The Sun is one million of times larger than the Earth. Though corn- Having discussed, subject of Comets, Stars. Besides the present us with an jjt^np^. 38 I'l fi- ■i Erelionding Stars difTering from each other', not merely in rightness, but in other essential {loints, they all agree in one attj'ibute, a high degree of permanence as to relative situation.. This has procured them the title of Fixed Stars, which may be understood in a com| arative, and not in an absoiute sense; it being certain that many, and probably all, are in a state of mo- tion, although too slow to be perceptible, unless by means of Very delicate observations, continued during a long series of years. Astronomers are in the habit of distinguishing the Stars into classes, according to their apparent brightness — these are termed magnitudes. The brightest are classed in the first magnitude, and so in succession ; and sizes horn the 8th to the 16th are familiar to those Astronomers using powerful in- struments — nor is there a limit to this progression. Such is tlie view taken by the late Sir William Herschell — so crowded are they in some parts of the region called the Milky Way, that by counting the Stars in a single field of his Telescope, he con- cluded that five thousand had passed under his review in a zone of two degrees in breadth, during a single hour's obser- vation. It is certain that light takes one thousand years to travel from some of the Fixed Stars to ns, — and it has been calculated that a cannon-ball, flying at the rate of 450 miles in an hour, would not reach Sirius from our Earth in 700,000 years. The light of many stars has not reached our earth since the crea- tion. Astronomers conjectm-e the distance of Sirius from us at 20 billions of miles — and Dr. Wollaston, with whom Sir John Hers- chell agrees, has conchided the light and heat of Sirius to be equal to 14 of our Suns. Whilst the writer was an under-graduate in the University of Dublin, the Rev. Dr. Brinkley, (lately deceased Bishop of Cloyne in Ireland,) was Regius Proliessor of Astrono- my. He concluded by a series of observations long continued on Lyrae, one of the Fixed Stars, that he had discovered its pa- rallax ; and on that interesting subject had a correspondence with many scientific persons in Europe, also with an eminent astronomer, the late Professor Play fair, of Edinburgh. Dr. Brinkley was, however mistaken — Astronomers are not infal- lible. The great Kepler, by too strict a dependance on the Rudolphine tables, then, in A. ^>. KiOO, in great credit, miscal- culated the time of the Transit of Venus, which he fixed for the year !l(i3' Hon-ox, who depended solely on his own tables, ca^ ^j ' o Transit to occur in November, 1039, correspond- ed^ . »t^ i>k f '^'id William Crabtree of Manchester, and was tiu - >~' «» to !•...•>-• ie the glorious sight of Venus, with her moun- taius, ?f ; , ' inents and forests, visible as a well defined black bpo\. Gi.- '>u^ Sun*s disc. Observe, the diameters of Venus and our Earth are nearly equal. The next transits will occur — first, on December 8th, 1874, — second, on December 6th, 1882. Bishop Brinkley mentions Horrox in his work on Astro- nomy, in a manner highly creditable to that prelate as a scho- lar, and to the extraordinary talents of that lamented youth. 29 )ly in n one latioiiv lay be ise; it jf mo- sans of ries of ig the -tliese he first 8th to rful in- $uch is rowded ay, that he con- ew in a 3 obser- ^ears to as been les in an )0 years. ;he crea- i us at 20 tin Hers- I be equal duate in eceased iVstrono- )ntinued d its pa- ondence eminent gh. Dr. lot infal- on the ^ miscal- 'd for the tables, respond- and was »r moun- defined [ofVenus ill occur iber 6th, »n Astro- . a scho- outh. n . LETTER IX. •% We have arrived near the conclusion of this Series. I will now enquire lor what purpose are we to suppose such maf^nifi- cent bodies scattered through the abyss of space, an the Fixed Stars are. Surely not to illuminate our nights, which an addi- tional Moon, infinitely smaller umn our Satellite, would do much better ; nor to sparkle as a pageant, void of meaning and reality, and bewilder us ni vain conjectures. It is surely true they are to man as " points of exact and permanent reference," but that man must have studied this noble Science to little pur- pose, who can suppose man to be the only object of his Crea- tor's care ; or who does not see in the vast and wonderful ap- paratus of Planets around us, the provision for other races of animated beings. The Planets derive their light from the Sun, but that cannot be the case with the Fixed Stars ; these, doubt- less, then, are themselves Suns, and may, perhaps, each in his sphere, be the pr-^siding centre round which other Planets or bodies, of which we can form no conception from any analogy oflTered by our own system, may be circulating within the bounds of infinite space'. Of the Fixed Stars Aldebran is red, Lyree a fine purple, Sirius a brilliant white. In my last Letter I iuiputed an error to the Illustrious Kep- ler. As I hold in such respect the memory of that great As- tronomer, that his name can never even be mentioned in my hearing, without exciting feelings of admiration, I now proceed, (as in candour bound,) to do him justice. The error I was led into by an imperfect edition of Ferguson's Astronomy, (Edin- burgh, 1812.) On close reading and research, I find in a His- tory of Astronomy, published by order of the Society for Pro- moting Useful Knowledge, (of which Lord Brougham was Pre- sident,) page 61 — Kepler had once imagined that he had ob- served a Transit of Mercury, on May 28th, 1607; but he soon admitted his eiTor, and frankly confessed that he had mistaken a Solar Planet, for the Planet on the Sun's disc. The Transit announced by Kepler, of Venus, actually occurred on Decem- ber 6, 1831, after his decease; but it unhappily took place in the night, of course unobserved. "There lived," say the Edi- tors of this History, "at an obscure village of Lancashire, Eng- land, (Hool, near Liverpool,) a young Astronomer, by nauK; Horrox, who, though he died prematurely at the age of twenty- two, has left behind him proofs of enthusiasm and genius tor this magnificent science altogether wonderful." Thus I again find 1 am not singular, in my admiration of the transcendant merit of that estimable youth. Fixed Stars of the 1st magnitude, are only twenty in number. These must be Suns illuminating other systems. These Stars much surpass our Sun in light and heat, as before stated res- pecting Sirius. The fixed stars are therefore surely Suns— c3 30 ill N nnd our Sun differs in nothing from a fixed star. The discs which the best Telescopes show us, of the Stars, are not real, but spurious, (an optical delusion ;) their light therefore must be our only guide. Stars of the second mag- nitude are sixty in number ; and there are two hundred of the 3rd magnitude. Stars classed as temporary, have appear- ed in difterent parts ofthe heavens, blazing with intense 'ustre, nnd have died away, and lefl no trace. Such a Star attracted the observations of Hipparchua, and induced him to make up a catologue of the Stars, the first on record. Such also was the Star which blazed forth A. D. 389, near Aquilla, remaining for three weeks as bright as Venus, and then totally disappear- ing. In succeeding years brilliant Stars aj)peared in the re- gions of the heavens, between Cepheus and Cassiopea. The appearance of the Star of 1572, was so sudden, that Tycho Brahe, a famous Danish Astronomer, returning one evening (the 11th of November,) from his Observatory to his house, was surprised to see a group of countrymen gazing at a Star which he was certain did not exist half an hour before. It was then as bright as Sirius, and continued to increase till it surpassed Jupiter in brightness, and was visible at noon day. It began to diminish in December, and in March, 1574, it had vanished totally. So also on the 10th October, 1604, a Star ofthe same kind, and not less brilliant, burst forth in the constellation of Serpentarius, which continued visible till October, 1605. Si- milar instances, though of less splendid character, have occur- red more recently,' as in the case of a Star of the 3d magni- tude, discovered in 1670, in the head ofthe Swan, which after disappearing, reappeared ; and after undergoing one or two fluctuations of light, during two years, at last died away totally. Many Stars are also missing. Some are found double, some treble. Sir William Herschell has noticed 500 Double Stars ; and Professor Struve, ofDorpat, (his telescopes being better fitted for obsei^vations,) has noticed five times that number ; others also have extended the catalogue. Many of the Double Stars exhibit the curious and beautiful phenomena of contrast cd colours; in such cases the larger Star is generally of a rud- dy or orange hue, while the smaller appears blue or green, — thUvS, a yellow predominating in the brighter, that in the less bright will appear blue, while if the colour of the brighter be crimson, the less bright will be green. The former contrast is exhibited by Canchri, the latter by Andromeda, both fine Double Stars. Cassiopea exhibits the fine combination of a large white Star, and a small one of a rich ruddy purple. The Nebul.TB furnish a boundless field of speculation and of conjec- ture — the greater part of them by far, consist of Stars, and in the interminable range of system upon system, the imagination is quite bewildered and lost. .■- . .= . ,; -■.•i ....,'/. vv . .' ...'.r . ,. . . ... "■fVii 31 LETTER X. The great improvement in the Science of Astronomy will appear and be obvious to all. At the end of the 16th cen- tury, a catalogue of tlie Fixed Stars up to that time discovered, by Tycho Bralie, Kepler, and by others, averaged fifteen hundred only. At the end of the 17th century, Flamstead doubled that number to 3000. In the 18th century, Lalande's Catalogue w^as published, containing upwards of fifty-thou- sand stars, and the number still increasing. Sir Isaac Newton, and Astronomers before his time, considered the Sun a vast body of fire. What are called Spots on the Sun are really the opaque body of the Sun, appearing through breaks in his atmosphere ; some are as large, or even larger than our Earth. The Sun is four- hundred times as distant from the Earth as the Moon ; our distance from the Sun has been be- fore stated — his real diameter is ascertained, and is eight-hun- dred and eighty-two thousand miles. The Sun is composed of matter much less dense that the Earth, and is surrounded by different strata of highly resplendent, and vast numbers of lu- minous clouds, whence arise his light and heat. The elder Herschell having given up the Moon to Schrseter, has devoted much time and attention to the Solar orb. His observations on its nature and properties appear very rational and conclusive. He computes the height of many Solar Mountains at 300 miles — this I think very incredible. The ap[)lication of his power- ful reflecting Telescope has expanded the heavens in a degree unknown, and even unanticipated, unless by Kepler and New- ton. Fancy, which was admissible in the infancy of the Sci- ence, cannot in its present matured state, be tolerated. We must in future depend solely on reason and observation. Previous to tlie establishment of the laws of gravitation, by Newton, several discoveries had been made, which opened the Avay to finding the Laws by Avhich the motions of the Planets round the Sun were regulated ; tliese were known by Kepler, and called the Laws of Kepler. They indeed form the basis of the Science. The first is — that tlie Planets do not move in circles as supposed by Copernicus, but in ellipses or ovals. The second, that an imaginary straigiit line, from the Sun to the Planets, always describes equal areas in equal times. The third, and by far the most remarkable and important is, that in the motion of the Planets, the squares of the periodic times of revolution, are as the cubes of the mean distances from the sun. It is quite incompatible with our limits, to enter into any de- tails respecting these important Laws; it is suflScient to observe that the application of them affords a fine explanation of the movements of the bodies composing our Solar System. (^-'oncerning " Perturbations," on which Mrs. Somerville has lately written in a most talented manner, that title has been ap- ^i^^^f^' / plied to those irrcptTlnrities in the Ltmar nrd Plnnetory mo- tions wliich ori^e irom the univereality oC tittr&ction. ThuH, not only does the Moon attract the Earth, ai d the Earth the Moon, hut the latter attracts the former, and both are again at- tracted by the Sun ; hut in tl.e lesp'er Systems, as in tlie Satel- lites of Jupiter, the Pertuibations thus arising, though insensi- ble in short intervals, become a|)parent when accumulated, and greatly derange the ecliptic motions and relations. The calculation of the effects of tliese listurbing forces are famoua in the history of analysis. We en \ ot here exhibit these nice calculations, nor would they suit < i r renders. Ot its great dif^ ficulty some idea may be formed, when we consider what is apparent to all — that the Planets are constantly changing their relative distances from each other. The attraction of Jupiter and of Saturn (the largest of the Planets) frequently delay Comets in their course, and [U'event their appearance at the times predicted. The attraction of Jupiter retarded the Comet of 1759,5-18 days; the attraction of Saturn retarded it ICO days. The works of a celebrated female (Mrs. Somerville,) are written in a style of scientific ability, quite beyond the reach of the uninstructed in Astronomy. I have rerd extracts from her late work on " Perturbations," which would have done credit to Sir John Herschell, or to Lnplnce. Lord Bacon says "Know- .ledge is Power;" the mother of the celebrated oriental scholar, Sir William Jones, on liis enquiring from her, whenever he met with difficulty in his studies, replied, " Read with atten- tion, and you will then know." The writer of these sheets has spent all his life in the acquisition of knowledge, and he finds he has much yet to learn. Newton modestly compared himself "to a child picking up pebbles on the sea-shore, whilst the great ocean of truth lay undiscovered before him." The Mecha- nics' Institute of Halilax, promises to afford much benefit in ex- citing and cherishing a disposition in the people to literature in general, and to science in [larticular. Ignorance is the mo- ther and the nurse of selfishness, and of all evil— this I know and have felt to my cost, during my residence in Nova Scotia. As the man who puts his hand to the Gospel Plough, and looks back, is pronounced by our Lord us unfit for his spiritual king- dom, so the man (the young man 1 mean,) who commences a course of liberal study, must persevere. If his memory be weak, he may take notes ; this, though gifled with a highly re- tentive memory, I have found an excellent plan. Nova Scotia need not despair ; some of her sons may at a future and no ve- ry distant time, do her credit. The fine prophecy of Virgil, in bis " Pollio," may then be realized even here : " Alter erit turn Typhis, et altera quae vehnt Argo Delectos heroas : erunt etiam altera bella, Atquc ilerutn ad Trojam magnua mittetur AcbillM." I ■ I *w9 - Another Typhifliihall new iieai explore ; Another Ar^o land tlie Chieta on the Iberian shore ; Another Helen other warn create ; And great Acliilles urge the Trojan fate. A glance of the view we linve just given of the Solar System, must convince us, that the puwerof gravity of any given Planet, will \)e in proportion to the mass of mutter it contains ; hence we calculate that bodies weigh three-fold more on Jupiter than on our Earth, on the Moon only one-sixth, while Saturn is much less dense than Jupiter ; but with respect to tempera- ture we cannot so well decide. We may 8[)eculate that Mer- cury endures a heut much above thut of boiling water ; and that Saturn and Uranus, from their great distance from the Sun, must be forever bound in chains of thick ribbed ice ; but the manner in which heat exists on otn* Earth is by no means set- tled. We know that both heal and light (ap|)arently) proceed from the Sun ; but the effect may be produced by some pecu- liar action which the Sun exercises on a rare etherial medium. With regard to Inhabitants, all that we can presume is, that (reasoning from analogy) they must be inhabited ; if not, pray for what purpose were so many Moons given to the larger Pla- nets ? If for itistance, upon our Earth there is not one wither- ed leaf that strews the forest or is found upon the heath, but teems with animated life, we are quite reasonable in stating our decided conviction, that they abound with creatures fitted to their respective climates. Saturn takes nearly thirty years in his Solar Revolution ; Ju- Siter takes twelve years ; Mars takes four years ; Venus and [ercury a much shorter period ; Uranus from his immense distance, a still more protracted period of revolution than any of the rest. Jupiter is thirteen hundred times larger than the Fa'th, and in the same ratio less than the Sim. More Planets of our Solar System probably exist, and may be hereafter discovered. P. S. I am hapj)y to learn that Dr. Olbers, of Bremen, has received ten thousand francs from the French Institute, as a re- ward for his discoveries of the minor Planets, and his labours on the Moon. LETTER XL Having finished Ten Letters illustrative of this most sublime and interesting Science, on further enquiry and research, we find ample materials for two others which will conclude the Series. That Astronomy is of great importance will appear from the efforts of all civilized Nations, in enlarging its boun- SKP^SJPWWWI ,<*;yi, "^Mf^^k ^..*^-,;'» 31 clurics mid rewording those who hnve expended t)jcir time nnd talents in this nohlo study. Tohins Meyer (a German) for his hihours on the Moon, received six thousand pounds sterling from our Parliament, and after his decease, (for ho did not long survive, having certainly injured his licalth by intense mental toil and research,) Jiis widow received a liberal Pension. Mrs. Homervillc also has had n Pension. Sir John llerschell notices a young Astronomer of great promise, whom ho styles " our young, talented, and unfortunate countryman, Mr. Gas- coine," who was contemporary and corresponded with Crab- tree and llorrox. 'J'hey are honorably noticed by Derham, Phil. Trans. nOth,(l. Horrox, he styles, and justly so, the " pride find boast oi' British Astronomy." As early as J(540, Gascoino had applied Telescopes with threads in the common locus of the glasses, to his (juadrants and sextants, and had even carried the invention so far as to illuminate the field of view by artificial light, which he found " very useful during the Moon's absence." 'I'he able Astronomers of his time expressed freely their admi- ration of this, and his varioi'" improvements in the art of ob- servation. Gascoiiie, however, was slain at the Battle of Mar- fton Moor, at the early age of SIJ, and llorrox, (as before stated,) died suddenly at the age of 2^, which ctilamities to Science Vyill fully account for the temporary oblivion of the invention. Our Letters on Astronomy, we trust will appear written with candour and strict imjjartiality ; we are not led by admiration of great names to adopt their errors ; we attach no credit to the elder llersciiell's remarks on the four small Telescoj)ic Planets, nor do we credit M. Schrreter's estimate of the height of the mountains in Venus and Mercury, — wc are disinclined to swal- low Whales. The discovery of mountains was a great effort of genius, w hen Herschell could not even perceive inequalities in their disc or surface. The discovery of the Yotation of Ve- nus and of Mercury on tlieir axis, is also due to the talents and ])erseverance of Schra:ter, — tlie spots certainly are the sha- dows of the mountains, and the spots on J'.i[)iter and Saturn are the shadows of the mountains in these innnense Planets ; tlie height of which is possibly proportionate to the size of the Planets. It was by carefully watching the rotation of the spots that the movements of the Planets on their axis has been j)rovcd. Uranus has no spots discernible, therefore the period of liis rotation is unknown. We have stated that the Planets perform their circuit in the Heavens under very different circumstances; this must be ex- plained. Mercury and Venus attend on the Sun within cer- tain limits, sometimes visible to the east and sometimes to the west of that luminary. In the former case they are visible over the western horizon first after sunset, and are called evening stars — Venus exhibits at times a dazzling lustre. When at the east of the Sun they rise before him in the morning, and ,.^^-. ♦, ^. :^v »» }S It Id appear on the eastorn hori/on as morning fitnrs ; tliey do not, however, attHin the same elungatiuii from the Hun. Mercury §008 no further than 21) degrees, whilst Venus extends to 47 egrees, and their continuance ahovo the horizon aller sunset becomes daily shorter, till at length they set helbre the dark- ness has rendered them invisible. Fur i rime, ttien, they arc invisible, unless on very rare occasions, wlion they may be ob- served passing over the Sun's disc, as small, romid, well de- fined black spots, totally different in appearance from the Solar spots. These phenomena are called Transits, and occur when the Earth happens to be ))assing the line of their Nodes, while they are in that part of their orbits. Alter being invisible for some time, they begin to a})pear on the other side of the Sun, at first showing themselves only for a few minutes before sunrise, and gradually longer as they recede from him ; at this time their motion is retrogade; they at length become stationary in the Heavens. Mercury and Venus alone perlbrm their Solar revolutions in the above manner ; tliey are called inferior Planets. Professor Struve, of Dorpat, has giveYi the exact dimensions of Saturn's Kings, concentric with the Planet, and with each other. These results are confirmed in his late work, by Sir John Herschell, also by Schrreter : — Exterior diameter of exterior Ring, Interior diameter of do. Exterior diameter of interior Ring, Interior diameter of do. Equatorial dia. of body of Saturn, 176,418 miles. 1.55,272 do. 151,690 do. 117,3:39 do. 79,160 do. Interior Ring, - - - 20,000 miles broad, Exterior Ring, - - - 7,200 do. Thickness of the Rings, 100 miles only. The Rings of Saturn must serve as Moons to his polar regions. I am at a loss to know, when the elder Herschell had the cre- dit of observing Saturn with gi-eat assiduity for years, why we are indebted to others for his dimensions. His great distance from us could be no apology, as the Fixed Stars and Nebulro are, beyond comparison, more distant. The most distant of his Satellites, which we have elsewhere stated as probably near the size of Mars, has alone elicited enquiry. This Satellite ex- hibits, like those of Jupiter, periodic defalcations of light, which prove its revolution on its axis in the time of a sidereal revolu- tion about Saturn ; the next in order is tolerably conspicuous ; the three next very minute, and requiring powerful telescopes ; while the two interior which just skirt t'le edge of the Ring, and move exactly in its plane, can only be discerned with the very best telescopes ever constructed. At the time of the disap- pearance of the Rings to ordinary telescopes, they have been 3a seen by Herschell, in his preat Reflector, threading like beads the thin fibre oflight to which it is then reduced, and for a dhorl time advancing off it, at either end, speedily to return and hastening to their habitual conrealineiit. Owing to the obliquity of the Ring, and of the orbits of the Satellites to Sa- turn^s ecliptic, there are no eclipses of the Satellites (the inte- rior excepted) until the time in which the Ring is seen edge- wise ; these iiighly im])ortant observations are confirmed by both the Herseheils, and given to the public by Sir John Herschell. This noble Science requires taste, talents, and warm feelings, industry, and intense mental application, a strong memory also. Men of cold and phlegmatic tempers, can make no progress in Astronomy, it would be irksonie to them. Whoever observes the firmament will frequently see the Planet Venus either a morning or an evening star ; her superior and transcendant lustre will render her an object almost impossibLj sed in its shadow, at a distance from it. The three interior pass through the shadow, and are totally eclipsed each revolution ; and the fourth, though it (sometimes) from the greater inclination of its orbit, escapes and suffers partial eclipse, yet this is rare, and its eclipses happen like those of the rest, each revolution. Tha Satellites^ with their respective Primaries, form in -'■ V M^ K ^syt x'' ni iM t 1 •'*f'^- l— 37 m each case miniature systems entirely analogous in the general laws of their motions to the great system in which the Sun acts the part of the Primary, and the rlanets of its Satellites. In each of those systems the laws of Kepler are obeyed with- out prejudice to the effect of perturbations, and of that small but not imperceptible connection which arises from the elliptic form of the central bodies ; and in all of them it will be observ- ed that the same remark respecting their proximity to their Primaries holds good, as in the case of our Moon, ^ :th a similar reason for such close connection. In those Transits of the Satellites, which, with powerful Telescopes, may be observed with great precision, it often happens that the Satellite is dis- cernible on the disc as a bright spot, if projected on a dark belt; but at times also as a dark spot of smaller dimensions than the shadow. This curious fact (observed by Schrceter and Harding) has led to a conclusion that some of the Moons Jhave, on their own bodies or in their atmospheres, obscure spots (as in the Planets) of vast extent; for the Satellites of Jupiter and of Saturn, small as they appear to us, are really bodies of great ei7.e, as we have before proved. The four Satellites of Jupiter cannot be eclipsed at one and the same time, for when the first is eclipsed, the other three must lie between the Sun and Planet, ■■ asting their shadow on his disc, and vice versa. One instance only is on record, when Jupiter has been observed without Satellites, viz. — by Molyneux, November 2d, O. S. 1681. The final and conclusive establishment of the Copernican System, may be referred to the discovery, of the motions and eclipses of the Satellites, in which the famous Laws of Kepler, and especially that Law which connects their periods and dis- tances, were clearly traced and fully maintained. To this cause we also owe the grand discovery of the aberration of light, and the enormous velocity of that element. The Orbits of Jupiter's Satellites are but little eccentric ; their mutual action produces " perturbations" in them, similar to those of the Planets about the Sun, diligently investigated by the celebrated French As- tronomer Laplace, and lately (as before said) with singular abi- lity by Mrs, Somei-ville. By close observation it has been as- certained, that they are subject to marked fluctuations in respect to brightness, and that these fluctuations happen periodically, according to their positions with respect to the Sun. From this it has been fully concluded, that they revolve on their axis like our Moon, in periods equal to their siderial revolutions round their primaries. We heretofore observed, that the Moons of Saturn require more attention than has hitherto been paid to them. He is cer- tainly inferior in density to Jupiter, but his being as light as cork I deny ; as in that case the " perturbations" arising from the action and attraction of Jupiter, would not only encumber his motions, but actually force him from his position in the sky. 38 That Comets are of a filmy texture, hae been proved by the ob- sei'vation of Stars through their body. All the conjectures of Astronomers are not founded on fact or proof ; for instance, Brewster says that Uranus has six moons, others say he has Rings and seven Moons ; Sir William Herschell, who discover- ed him, and his son, who has frequently observed him with powerful telescopes, both join in stating that " he has certainly two Satellites, and that four more are suspected." I again gay "suspicion is not proof;" but it is in my humble judgment highly probablo that Uranus, from his bulk, (eighty times that of our Earth,) has four Moons at least ; this is more probable than that he has two or six, when the immense Jupiter has four only. Except the two interior Satellites of Saturn on the edge of his Rings, the Moons of Uranus are by far the most difficult objects in the Solar System to observe. The elder Herschell has the credit of their discovery. Mercury, I have never been able to see in his place in the Firmament. I have observed him, however, from Halifax, being aware of his Transit, (I think early in the summer of 1830,) as a dark well defined spot of the size of a dollar, remaining for three hours on the Sun's disc — a partial eclipse of the Sim took place ; my eye was pro- tected by a smoked glass. Venus on the Sun, some of our children may observe twice in this century. We will now afford an illustration calculated to convey to our readers a general impression of the relative mag- nitudes and distances of the Solar System. Select a level field, on it place a stone 9 feet in diameter, this will represent the Sun ; Mercury will be a grain of mustard seed, on a circle 164 feet in diameter for its orbit ; Venus a pea, on a circle 284 feet in diameter ; the Earth a pea, on a circle of 240 feet ; Mars a large pin's head, on a circle of 654 feet ; Juno, Ceres, Palas, Vesta, grains of sand, in orbits often or twelve thousand feet ; Jupiter a large orange, in a circle half a mile across ; Sa- turn a smaller orange, on a circle of 4-5ths of a mile ;'and Uranus a cherry, or a small plumb, on a circle li mile in diameter. To obtain correct information from childish toys called Orreries is futile. To imitate the motions of the Planets in their orbits, Mercury must describe its own diameter in 41 seconds ; Venus in 4 minutes, 14 seconds ; the Earth in 7 minutes ; Mars in 4 minutes 48 seconds ; Jupiter in 2 hours 56 minutes ; Saturn in 3 hours 13 minutes ; and Uranus in 2 hours sixteen minutes. LETTER XII. , ;. The first Edition of these Letters having been sold within a few days of their publication, added to the increasing interest towards the attainment of correct information respecting this L'h "*. 'f hM i^td^mmam j^jt^ f^r :-M ">Ti 4>J .&:^^^:- iV >Jvt.-,. i •'/iv.'.V'.v fiv* MiM^ip L'esent circle e284 feet ; eres, sand ;Sa- anus To lies is rbits, lenus in 4 iturn lutein. iin a irest this 39 noble science, has induced us to add two letters and a supple- ment to this, the second Edition, having still more interesting notices to* impart concerning the Planets Jupiter and Venus, the Comets of our system, and the Fixed Stars and Nebulte. With regard to Venus : the motion of certain spots, first ol>- eerved by Cassini, instructed that Astronomer that her rotation on her axis was performed in rather less than twenty-four hours. Schreeter, by continued observations of her horns, and of some luminous points in her disc, has confirmed this result, which was doubted, and like Cassini, has found her Equator to make an angle with the ecliptic. He has also ])roved the existence of high mountains, and from the lawr by which her light gradually varies from her bright to her oles of its axis ; — the moons of Jupiter appear nearly in a line with the belts of the Planet. We will here note, that an obser- ver in Jupiter will never see either Mercury, Venus, the Earth, or Mars, as from the immense distance at which he is placed from them, they must ai)pear to accompany the Sun, and to rise and set witli him. His own four Moons — the Planet Sa- turn, with his Rings, Satellites, and probably, Uranus also, may be visible from Jupiter. With respect to the Laws of the Planets' revolution, it re- quired no common sagacity in the Illustrious Kepler, assisted by singular perseverance and industry, at a period when the data themselves were involved in obscurity, and the calcula- tions were encumbered with difficulties of which recent im- provements have left us no conception, to f erccive and clearly to demonstrate the real laws of their connection, as before Mated and proved. But of all the laws to which induction 40 from observation has ever conducted man, his third law J8 the most pregnant "with important consequences. It is no longer mere analogy which strikes us ; no longer a general re- pemblance, as individuals, independent of each other, and cir- culating round the Sun, each according to its own peculiar na- ture : the resemblance is now a true family likeness — they are bound up in one chain — connected in one web of mutual rela- tion, and harmonious agreement — subjected to one per^'^ading influence which extends from the centre to the farthest limits of that great System, of which all of them (the Earth included) may henceforth be regarded as members. These most impor- tant laws are established by the great Kepler, as deduced from his observations on Mars, and extended by analogy to the mo- tions of the other Planets. However precarious such an ex- tension might then have appeared, modern Astronomy has ve- rified it as matter of fact by the general co-incidence of its re- sults with the series of observations of the apparent places of the Planets. Having so far treated on the famous laws of Kep- ler, the very basis of our noble science, we will devote the re- sidue of this letter to additional information respecting Comets. We heretofore observed that Comets were greatly impeded in their courses by the attraction of the greater Planets. Jupiter by some fatality is constantly impeding their movements by his great attraction, and even totally changing their Orbits. In the case of the remarkable Comet of 1770 which was found to revolve in a moderate elipse of 5 years, and of course expected, the Comet was signally retarded, and its predicted appearance frustrated by its getting entangled amongst the satellites of Jupiter, — ar d being completely thrown out of its Orbit by his attraction, and forced into a much larger Elipse. The motion of the satellites however suffered no perceptible disarangeinentt a convincing proof of the smallness of the Comet's mass, — and the filmy nature of its texture. We will observe that Comets in their course describe long narrow ovals, that they approach the Sun in one of the ends of these ovals, and that when a Co- mets in one of the ends of its orbit, its distance from the Sun is incalculably great. The nearness to the Sun gives a Comet an immense increase of motion. The velocity of Halley's Comet of 1680 (the greatest on record,) was calculated by New- ton at 880,000 miles an hour, being distant from the Sun 580,000 miles only — little more than half the Sun's diameter. This prodigious Comet, descended from ihe upper regions of space, and having passed round the sun, ascended again ; — it was visible four months. Its tail was of enormous length, extend- ing over a space in the heavens nearly equal to one fifth of its whole circumference, the velocity of this Comet in its perihelion passage, would have carried it thro' 124 degrees of a great circle within one hour. From Halley's determination of the orbit of tliis Comet, its distance from the Sun, when in its aphelion can- cisu. ..- n. > ;. notbcl^ss than ]3 thousand Millions of miles. A Comet ap- pears as a sky Rocket discharged by an Almighty Hand. Our readers may be amazed to hear that the so celebrated Comet •of 1680 travelled swifter than a cannon ball, and drew after it u tail (by Newton's computation) Eighty Millions of Miles long. The heat of this Comet exceeded by ten thousand times the heat of red hot Iron. How amazing that it should move with such great fury, and with such exact regularity ! How spacious must the IFniverse be, that gives Comets full play without suffering the least confusion ! When the terrors which «uperstition and astrology had formerly excited, fled before the dawning of Philosophy ; when Newton, unfolding the system of the universe, had described the Laws by which the motions of Comets are directed, and Halley had carried his theory to a high degree of certainty, — a novel kind of apprehension arose, it was, and is still feared by the vulgar, that some Comet would meet the Earth in her evolutions and consume her, and her in- habitants. Thus a talented philosopher ( Whiston) considered the Deluge as produced by the tail of a Comet, and supposed also that our earth would finally be destroyed by the agency of a Comet on its return from the sun. I am of opinion that the theoiy of Whiston respecting the destruction of the Earth by passing through some great Comet, may be correct. I am not aware of Newton's opinion on this subject. y>- LETTER Xm. I was md- its llion Ircle It of jan- Intending, with the Divine blessing, this our last letter as an interesting addition to our former notices, respecting the fixed stars, and Nebulpe ; and having, by fair analogy as we trust, proved the fixed Stars, Suns — generally the centres of other systems, and that our sun in no respect ^differs from a fixed star ; we will observe that, in respect to the magnificent sub- jects now before us, it is surely not with the revolutions of bodies of a Planetary or Cometaiy nature round a Solar centre that we are now concerned — it is with sun around sun ; each, perhaps, accompanied with its train of Planets and their Satel- lites, closely shrouded from our view by the splendour of their respective Suns. Unless closely nestled under the protecting wings of their immediate superior, the sweep of their other Sun in its Perihelian passage round their own, might carry them off, or whirl them into orbits utterly incompatible with the con- ditions fitted for the existence of their inhabitants. It must be confessed that we have here a strangely wide and novel field for speculative excursions. When we observe the spacious concave of the Heavens, we must perceive grouping stars which »eem compressed together, forming briglit patches and p3 42 clusters, which attract attention as if resulting from some cause other than casual distribution. Telescopes exhibit sixty large stars thus crowded into a small space. The Constellation call- ed " Coma Berenices'^ is another such group, more diffused, and generally consisting of much larger stars. A French Astro- nomer (Messier) has given a list with which all who seek for Comets ought to be familiar, to avoid being misled by their si- milarity of appearance. That they are not Comets their fixity proves, as also on close observation with powerful Telescopes, they appear to run up to a blaze of light in the centre, where their condensation is usually thn greatest. It would be in vain to attempt to count the stars in one of these clusters, globular as they appear ; they cannot be reckoned by hundreds, and on a rough calculation, it would appear that many clusters of this description must contain at least ten o twenty thousand stars, compacted together in a round soafo whose angular diameter does not exceed eight or ten liim , t\ an area not more than a tenth part of that covered by t) lo ... On the one hand, without a rotatory motion and a ceuiriiugtil force, it is impossible not to regard these stars as in a r-tate of progressive collapse ; on the other hand — granting sucu a i >tioi '1 such a force — we find it no less difficult to reconcile the appp''^ it sphericity of their form with a rotation of the whole system round any single axis, without which internal collisions would appear in- evitable. We will here observe that every improvement in telescopes has led to the discovery of countless stars not seen before ; it would therefore be censvu'able in us to set bounds to their number. Nebulous stars are those which show a dim light; they are less than stars of the sixth magnitude, and are seldom visible. The Milky Way, Dr. Herschell found to con- sist of vast clusters of minute stars. The Nebulse are arranged into strata, (says Herschell) and run to a ^'"•reat length. One of these Nebulous beds is so rich, that in passing through a sec- tion of it in thirty-sij^ minutes, he discovered thiity-one Nebu- Ise ; their situation and shape, as well as their condition, denoted great variety. In another stratum I have often seen double and trible Nebulae, variously arranged : large ones with attendants — narrow lucid .Nebulae — some the shape of a fan, others of the Comet shape, or like cloudy stars surrounded with a Nebulous atmosphere. Herschell resolves all Nebulae into six classes : 1st, Clusters of stars, in which they are all perceptible — 2d, Resolvable Nebulae, or such as appear to consist of stars. 3d — Such as have no appearance of stars, divided into classes, ac- cording to their appearance and size. 4th — Planetary Nebulae. 5th — Stellar Nebulae, and 6th — ^Nebulous Stars. In some parts of the zone in which they are placed, they are very numerous, being, however, for the most part telescopic, and beyond the reach of any but the most powerful telescopes. Annular Ne- buloe also exist, but are extremely rare ; the most conspicuous ^'r. *N \ may be^found exactly halfway between the stars Lyree, and is visible with a telescope of moderate power. It is small and well defined ; so as in fact to have much more the appearance of a flat oval solid ring tlian of a Nebula, The axis of the el lipse are inversely in the proportion of four to five, and the opening occupies about half its diameter; its light is not quite uniform, but has a curdled appearance at the outer edge ; the central opening is not entirely dark, but is filled up with a faint hazy light, uniformly spread over it like a fine gauze ex- tended over a hoop. Planetary Nebulse are very singular ob- jects ; they exactly resemble the Planets : round, or slightly oval discs, in some instances quite sharply terminated, in others a little hazy at the borders, and of a light very equal, or only a little mottled, which in some is as vivid as the light of the Planets. Whatever be their nature, they must be of enormous magni- tude ; one is in the parallel of Aquarii — its apparent diameter 20 degrees; another in the Constellation Andromeda, presents a visible disc of 12 degrees, perfectly defined and round. Granting these Nebulse to be from us as distant as the stars, their real dimensions would fill the whole orbit of Uranus. It is no less evident that if they are solid bodies of a solar nature, the intrinsic splendor of their surfaces must be infinitely infe- rior to that of the Sun's. A circular portion of the P^un's disc describing an angle of 20 degrees, would give a light equal to 100 full moons, while the objects in question are hardly dis- cernible with the natural eye. The uniformity of their discs, and the want of apparent central condensation, would prove their light merely superficial, like a hollow spherical shell, but whether filled with solid or gaseous matter, or quite emptyi> it would be a waste of time to conjecture. The Nebulae fiirnish a boundless field of speculation and conjecture. That the greater part of them consist of stars there can be no doubt, and in the interminable range of systems, and firmaments, which we can merely glance at, our minds are quite confused. On the other hand, if it be true, as it seems extremely probable, that a phosphorescent matter also exists, disseminated like a cloud or fi)g; now assuming capricious shapes, like clouds drifted by the winds, and now concentrating itseH* round some particular stars, what, we ask, is the nature and the destina- tion of this nebulous matter? Is it absorbed by the stars, in whose vicinity it is found to furnish, by its condensation, their supply of light and heat, or is it progressing by the effect of its own gravity into masses, and in laying a foundation of new siderial systems, or of insulated stars? It is much easier to propound such questions than to reply to them. Meanwhile, appeal to fact, by constant and diligent observation, is open to nil ; and as the double stars have yielded to this style of ques- tioning, and .disclosed a series of relations of the most intelii- iTW*'^'" 44 gible and intcreHting deBcription, we luny fondly Lope that tlie diligent study of the Nebulee will, ere long, lead to a more clear and definite understanding of their intimate relationship and peculiar nature HENRY HAYDEN. K< ' I •'•• SUPPLEMENT. Although we have occupied much time in investigating and in delineating the nature, structure, and real state of the Lunar regions, we find we can still occupy this our Supplement with further interesting notices ; as, of all tlie curious discoveries which the Telescope has afforded us, those relating to our Moon are by far the most interesting. She appears to us next in splendor to the Sun, and being the inseparable companion of our Earth, and much nearer to us than any of the Planets, she is the object to which an Astronomer will naturally direct his chief attention. The full Moon is certainly a very beautiful object as seen through a powerful telescope, and exhibits a great variety of lustre and colour: — -TJie Moon , ^ Full orb'd, and breakintr tliro' the scattered clouds, Shews her broad visage in the crimson 'd East, , '. Turned to the Sun direct her spotted disc, Where mountains rise. An Eclipse is the shadow of the Earth falling on the Moon, or the shadow of the Moon falling on the Earth. The Moun- tains are best observed at the respective times of her increase and decrease. Different conjectures have been formed res- pecting the matter of which these brilliant spots are composed. Some are so charmed with their beauty as to imagine them rocks of diamonds: — it seems more reasonable to conclude that they are thp tops of sterile mountains which, by reason of their great elevation, are more capable of reflecting the Sun's light than the common parts. Of their use there can be no diversity of opinion : as, if she were smooth, in some positions she would show us the Sun's image no larger than a point, and with a lustre that would hurt our sight ; but, diversified with moun- tains and valleys, her surface reflects the Sun's light to us in a soft:ened and delightful manner, and enables us also to examine every part of her immense disc with ease and precision. The Phases of the Moon are her most striking phenomena ; in dis- engaging itself in the evening from the rays of the Sun, it re- appears as a splendid crescent, which increases with its dis- tance, and becomes an entire circle of light, when in opposition to the Sun. When it afterwards approaches to it, the circle is , { r ( mm 4 - ■ »; V a me 'he is- re- is- on *;■.■• K M changed Into a crescent, which diminishes in the same degree by which it had increased, till in the morning it becomes im- mersed in the Solar rays. The lunar crescent, always turned towards the Sun, evidently indicates that it receives its light from the Sun alone, and the law of its variations prove it spherical. The inclination of the Ecliptic to the Equator occasions a peculiar phenomenon of the Moon, called the Harvest Moon. This appearance is owing to the peculiar ascent of the Eclip- tic, as may be discovered by turning a globe. Some signs ascend rapidly, and obliquely, others slowly and almost perpen- dicularly ; and it is while the full moon is in the former, that the Harvest Moon takes place. The Harvest Moon is always visible in the month of September. It depends clearly on the obliquity of the Moon's path with our horizon. The inhabi- tants near the Equator observe it not. The Harvest Moon is caused by the same circumstances which cause the days so ra- pidly to increase, or decrease, at certain seasons of the year. The bright spots are the solid parts of high mountains, which strongly reflect the Sun's light ; the dark caverns reflect no light. Mountains, some of immense height, as before |)roved, rise up from the surface of the Moon; their shadows projected on the plains from spots which vary with the position of the Sun upon the edge of the enlightened disc. We see these mountains, forming an indented border, extending beyond the line of light. We observe, also, by the direction of the sha- dows, that her surface is broken by currents, resembling the Basons of our seas. Lastly — the existence of divers volcanoes, as we have fully proved, confirms the indications of her having a rare atmosphere — as fire cannot exist without air; this, in my judgment fully proves that contested question. Ricciolus indeed asserts that the Moon and her macul