網頁圖片
PDF
ePub 版

him of the only safe quarter of retreat. A panic seemed my eye and worship of my soul, until I hand her safe to seize the bandit, when he heard that Marion was one to your presence." of the pursuers. He only halted long enough to order “Well, that's another thumper, by your leave, good a counter march, and wheeling his troop around, the Mac; howsomever, go on to the end,” muttered Sweewhole gang soon were beyond the fear of molestation. ney.

When we were quite clear of them, Sweeney roared "As I was saying, with the General's favor I broke cat in a hearty fit of laughter, to see how completely ground, and kept our steeds up to their mettle the the deception had succeeded; the whole affair being a whole way; for who dare say, McDonald stay your fabrication of his own, executed by the same deserter course, unless I've a mind to it? But, honored lady," whose uniform served his purpose.

he said, addressing me, “ you have but to command, The next day we travelled through by-ways, but and all we,” pointing to his troop, " obey. Pardon the still were often obliged to resort to Webster's passport rude manner of a soldier, while I greet you in the name for protection, so completely was the country infested of my commander, and offer you the service of my with the friends and allies of the enemy. Night found hands and devotion of my heart.” s still plodding our weary way, our only beacon the I thanked the rough soldier for his kind intentions, twinkling stars above, and the dashing of the river, and told him my only desire was to lose no time in whose course we were following. Sweeney kept his reaching the place of our destination. eye fixed on the unerring lights above; and calculating About day-light we halted to renew our strength by time by the progress of these silent travellers in the rest and taking some refreshment, from which I had heavens, guessed the hour to be midnight. His specu- abstained while beset by dangers. I observed the men lations were interrupted by the sound of a distant bugle. to eye me with surprise and curiosity. Doubtless the

"Hush !” exclaimed he; rein up your beasts a spell. singularity of my appearance struck them as something I think, if my ear be true, that is McDonald's note.” incomprehensible. Sweeney soon took an opportunity

"What, Sweeney, another ruffian? I tremble at to explain all, but in so low a voice as to escape my every sound."

ear, and afterwards they preserved the most respectful "Tremble, indeed! I'm thinking it's the sweetest silence. sound as ever come over my ear yet; and I'm no way At mid-day we came in view of the American lines. surprised neither. It's jest what I looked for, as soon I shall ever retain a lively impression of the effect on as I got word to the General that we was on the way, my feelings. My heart bounded with joy when I beAs sure as my mammy's name was Grace, its jest Ser. held the star-spangled banner waving above the camp, geant McDonald coming to marshal us all to head-quar-where every heart beat in unison for country and home; ters. So you see, Miss, we an't folks of small account and I forgot my own petty cares, when I thought that neither. And tho' the Sergeant's a rampagious sort of the weal or woe of a great nation hung on one single fellow, he an't guine to run his head agin a post, not movement of this army. Marion met me as we entered he; he's as true steel as ever bent, and that's why the the American lines, and clasping me to his bosom, asGeneral sent him. The British run from him like Lu- sured me of his love and protection. cifer, because they think he smells of the brimstone. The army was soon in progress towards its rendezListen, he's tooting again, and making right up to us." vous between the Pedee rivers. My uncle obtained me

In a few moments the party came up with us, and very agreeable quarters every night among the whig McDonald demanded who we were.

inhabitants, who rallied around his standard, while the " Jest the stragglers, honey, you are looking after, 1 loyalists fled at the terror of his name; so that our guess," replied the lively voice of Sweeney, “for you march was without interruption until we reached Snow's are nobody if you an't McDonald, come to squire us on Island, where Marion took up his quarters. This was to head-quarters.”

one of the most impervious fastnesses imaginable ; "Exactly as you say; the General was rather un- surrounded by morasses and running streams on every easy when he heard Butler was prowling in these side; the only accessible point of approach lying conparts; and he said to me, 'McDonald,' says he, there's cealed from common view. We had to wind our way no man in my brigade can cope with that marauder like through a canopy of evergreens, from whose leafy arms yon.'"

hung a drapery of mossy fringe, decorating and shield"You a leetle more than hit it off, Mac,” replieding our sylvan retreat. Gen. Marion selected an emiSweeney, with suppressed humor ; "something like it, nence on this island as the spot of encampment. Tents I dare say. But go on.”

were soon erected, and lights struck, in the deep green "Take jest such men as you choose from the troop, solitudes, which seemed hitherto to have been the fairyand scour the road to Charleston, until you overhaul land of a poet's dream. In its labyrinths I enjoyed John Sweeney, who has my niece, Miss Marion, under delicious repose, and felt å companionship with its his care, and conduct them safe to my quarters.'” secret haunts, which told me that nature has a voice,

"Not them, Mac; the General knowed I was up to In every“ leafy bough and bursting rill,” she replies to conducting myself, and you too, if there was any occa- the sympathy of the human heart. sion. Don't stretch your commission, man; it was the I had quite forgotten I was in the camp of Mars, lady the General had in mind."

when my uncle came to tell me of the arrangements he " I'm an officer under commission, remember that, had made for my accommodation. I saw satisfaction and speak by authority. “I charge you,' says he, 'that and complacency beam on his brow, as he began : no evil befall her while under your protection. 'I “Dear Constance, I have not told you yet, where Swear, General,' says I, that by every saint in the your quarters are to be during this campaign.” calendar, and that's not a few, she shall be the jewel of “No, uncle," I replied, "and your's here are so

VOL. VI-16

romantic, that I think I am spell-bound. But, to speak have known her in prosperity and joy. I cannot say seriously-who has courage to harbor a rebel and run in which she was most lovely." away?"

“Oh, in both," I replied with warmth ; "her charms “Who would you guess? I have been silent, until are surpassing: in which declaration, I think I can I could give you the agreeable surprise.”

perceive with a woman's penetration, you will agree." "How, uncle, can I imagine the person, in a land of The conscious glow passed over his cheek, and lent a strangers ?"

momentary smile to his countenance, as he answered, Do you call Edith Norwood, your old school-mate, “Certainly, I will not refuse to confess, Miss Marion, a stranger ?

if you will be priestess.” "My sweet Edith! Ah, uncle, would you mock “That I will," I said, “and promise to give you my heart's early affection? You know her father was hearty absolution for the sin in question.” obliged to leave the country, because he espoused the My uncle broke on our discourse, by calling out that cause of liberty too warmly."

he perceived Col. Norwood had reached the ford before “I know he left the hot-bed of toryism : but what us. We quickened our pace, and looked forward to if he settled peaceably in the truce ground ? and what the spot, which now began to appear through the if Edith should meet you at the Black-river ford to spreading growth that overhung the river. Could that morrow, and conduct you to her residence, only a few tall and graceful figure, whose plumes floated on the miles distant, would you not think me as great a wiz- breeze, while with fearless skill she reined in the fiery ard as the British do ?”

spirit of the steed on which she was mounted, be Edith, I could scarcely reply. Joy and surprise held me for my little playmate, who used to bound over the sands a moment speechless. Should I meet again the friend or hedges to pluck a favorite flower or gather shells on of my heart, and taste again that communion of soul, the beach, at the risk of frock or bonnet ? The ques. which my lonely spirit had pined for so long! The Lion was not answered satisfactorily until we embraced thought was transporting-I lived on it until the hour each other, when I found the same soul, warm and of my departure arrived.

true, inspiring a more mature and perfect beauty.I was accompanied by my uncle, my old attendants, After our mutual salutations were over, she greeted my John and Kate Sweeney, and Lieut. Stuart, whom uncle most cordially, and then turned to speak to Lieut. Marion introduced to me as my protector to Col. Nor-Stuart. I thought her color brightened, as their eyes wood's residence, it being out of his power to proceed met; but in a moment she regained her self-possession, farther than the ford.

and gaily inquired of Gen. Marion, whether his treaty When I first encountered the glance of the stran- with the insurgents forbade his acting the squire of ger's eye, I almost shrunk from it, such was the awe dames within the prescribed limits. My uncle replied inspired by his presence. And it was not until I en in his dry vein of humor, that he had made no treaty tered into conversation with him, that I found united yet with duty, which told him that he must not purwith this power and decision of mind, all the gentle chase even Miss Norwood's smile at so great an kindlings of the heart. His figure was tall and athletic; expense. Edith's look of pleasure showed that she the keen gray eye and high forehead, marked the daring accorded with the sentiment; and with hearty wishes of a soul fearless in danger and untiring in effort. on both sides, we parted with my uncle, who returned

The taciturnity of the General, left the conversation to his quarters. chiefly to Lieut. Stuart and myself; and I found that A few hours' ride brought us to the residence of Col. he could lay aside the stern warrior, and unbend his Norwood. It was a sweet sequestered spot, crowning mind to all the grace and elegance of polished society. a gentle eminence on the Pedee. Ils embellishments As all the ceremonials of fixed life were out of the were only such as suited the simplicity of rural life, question in the circumstances in which we were placed, assisting, but not deforming nature. I was welcomed making our way through the impediments of the wild by all with heart and tongue, and felt that I was giving wood, we soon improved our introduction into the as well as receiving pleasure by coming into this happy openness and pleasure of unrestrained intercourse. He family. gave me a history of the war waged on the unsuspect- We had poured out our thoughts in gushing flow on ing inhabitants of the frontier, by the marauders under various subjects, and yet the one name nearest my British colors, which had induced General Marion to heart had not been mentioned. At length Edith said, enter into a truce for a limited time.

with something like mortification, “Constance, have “And my dear Edith lives in this truce ground, I you forgotten Sydney? I am sure you have, or you think my uncle said.”

would at least have missed him from our little circle." “Yes," he replied with pleasure beaming in his eyes, I endeavored to make some excuse; but the truth “Col. Norwood's family, I hope, are now secure from was, that I feared betraying more interest than I all danger ; but they have suffered severely from the wished any one to discover. I suppose my blushes ravages of this barbarous warfare. It was in defending emboldened Edith to go on, for she wound up by their persons and property from brutal violence, that I saying, "Well, I will tell you, my lady, if he has first saw the lovely daughter of Col. Norwood.” faded from your memory, you have not from his.

“So then you are personally acquainted with Edith,” By the way, I expect him in a few days from CharlesI said, looking archly towards him; for I imagined ton, where he has gone to gain intelligence of the there was something like pathos in the tones of his movements of the enemy." voice as he spoke of her.

It had been two years since Norwood and myself “I have seen Miss Norwood in the most interesting had met, and yet I felt a sort of consciousness when of all situations-in adversity and tears; and again Il he was named, as if he were present and reading my heart. That full blue eye, which seemed but the portal and ornamental arts. The theoretical mechanician, by of a noble soul, that high forehead, shaded with cluso giving verbal expression to his analytical formulas, has tering ringlets, that arched lip, now curled in disdain, with his most useful and comprehensive rules. Thus,

in many instances furnished the practical mechanic now melting into an ineffable smile, that form of slight by pointing out the available resources of these branches but graceful proportions, still lived in the fond record of of science, considerable importance has been attached youthful memory; but they were like the sacred relics to their acquisition, and the learning of books has been which the heart of the devotee cherishes too much to duly respected and prized. But the epithet of starsuffer them to be gazed on by others,

gazer, is still somewhat sneeringly applied to one, who, I had told Edith of young Heyward, his character notions; as though astronomy were of no real worth,

upon any subject, entertains fanciful and extravagant for gallantry, and the horror and dislike I felt at being and had contributed but little to the progress of civilithe object of his admiration or love, and my joy at es- zation and to the comforts and refinements of life. One caping from his presence; but I had never spoken to would have thought that its assiduous cultivation by her of Col Webster. I felt a sort of self-reproach when such men as Newton, Halley, Delambre, Lagrange and I thought of him, as if I had requited his kindness with Laplace, might have rescued it from a contempt like

this; for what department of science can boast of ingratitude ; and when Edith inquired about him, as an names such as these? The truth is, astronomy is not exception to the generality of the British officers for only the queen of sciences, but the stricter sense of generosity and honorable feeling, I spoke of him only as the word, is the only perfect one. In other sciences, it a casual acquaintance, in whom I felt no particular in. is probable that succeeding ages will continue, as they terest, and dismissed the subject as soon as possible.

have hitherto done, to modify, if not wholly to change [To be concluded in our next.]

the expression of laws now considered general and well established. Important revolutions are likely to take place in the sentiments of the learned relative to many of the present received laws of chymistry, optics, geology and other departments of science; while, on not

a few points, even involving the elementary principles AN ADDRESS ON THE

of these subjects, there exists much diversity of opinion.

The atomic theory cannot yet be considered as inconUTILITY OF ASTRONOMY: testably established. Chymists are not agreed as to

the nature of caloric-and of chymical attraction. As Delivered before the “Young Men's Society" of Lynchburg, to the constitution of some of the acids, as well as the

Sep. %s, 1937, by Professor Landon C. Garland, of Randolph existence and relation of the sulpho and chloro salts, Macon College and published by request of said Society there are many questions undecided; and an obscurity in the Southern Literary Messenger.

still rests upon several important processes, as upon GENTLEMEN,

that of combustion as far as the production of light and Had I not in my judgment fully approved the method heat is concerned, and upon all the cases of disposing by which you hope to excite a deeper literary interest affinity. Even the best established laws of chymistry among yourselves as well as others; and had'I not felt cannot conduct us to results, on which we can rely it to be my duty to contribute, when called upon, even without subjecting them to the experimentum crucis. in my humble measure, towards the attainment of so In physical optics," the representation of all the series worthy and important an object, I could not have ob- of polarized 'tints and the colors of natural bodies by tained my own consent to occupy a place, for which I a certain universal scale-the Cartesian law of refracam conscious I possess but little fitness. But how I tion when applied to the extraordinary ray in crysmay best discharge this duty, I have been at some loss tallized media-together with innumerable other laws, to decide. Among those subjects, to which from choice simple, natural, and resting on extensive inductions, or profession, my mind has been particularly turned, have all been either overset, extended, or materially I have found it difficult to select one, which will admit modified by the progress of the science.” (J. F. W. of being clearly presented in a popular form and within Herschel.) 'Though the discussion has been carried on the compass of a single hour. Believing, however, that with renewed interest of late, it is yet difficult to dean interest in the sciences generally, is to be excited cide between the rival claims of the theory of undulaand maintained only by pointing out their applicability tion and of emission. In cristalography, we know not to the common affairs of life, I have ventured on this what modifications may take place, when the facts of occasion, to press upon your attention the claims of one dimorphism and plesiomorphism shall have been collected branch of physical science, which in this country has and classified, and the laws they follow discovered. not been duly appreciated.

Geology, in many of its most important features, is still The chymist unfolds the wonderful properties of more unsettled; and the cultivators of a science can steam, and exhibits its almost creative energies as a scarcely be more at issue than geologists have been, or prime-mover of machinery. With those beautiful laws, even than several very distinguished ones now are. which control the combination of substances, both sim- This can be hardly otherwise, since but a small portion ple and compound, he connects the application of the of the earth has been examined, and that to a depth substances themselves to a thousand useful purposes not bearing to its whole diameter a proportion greater both in medicine and the arts. The geologist interests than that of the thickness of a coat of varnish to the us with the structure of our globe and the fossil con- dameter of an eighteen inch globe. tents of its strata, which like ihe medals and inscrip- But how different is it in physical astronomy! Here tions of an ancient empire, are supposed to point out our first conclusion is our last. Here particulars have those tremendous convulsions by which whole conti- been completely subjected to generals, effects to causes. nents have been at successive periods up-heaved from The united wisdom and experience of succeeding genethe bosom of the ocean, and others buried beneath its rations will add nothing io its theory. The only reWaves. He regards them, indeed, as historical records maining work for future astronomers, is to determine of the changes to which the earth has been subjected with the extreme of accuracy the consequences of its in assurning its present physiological character, which, rules, by the profoundest combinations of mathematics; notwithstanding the obsoleteness of the language, he and the magnitude of its data by the minutest scrupuconsiders as unequivocal and satisfactory. The miner- lousness of observation. And in this last respect, but dlogist unfolds the hidden riches of the crust of the little may be hoped for, unless instruments can be con. earth-examines its materials-their respective locali- structed and adjusted with a nicety, which seems alties--and shows their various applications to the usefull most incompatible with the productions of the most

ences.

consummate skill. All the phenomena of this science "hosts of heaven," and regulated their rapid, yet calm depend upon a single law, which may be deduced from and harmonious motions, by laws the most beautiful and the simplest among them and by the rudest observation ; simple, and evidently the mere extension of those which and which has been put repeatedly to the severest trial, are in daily operation around us; and we be not alby a series of discoveries unparalleled in number and lowed to investigate these things, because they do not delicacy :-such as the precession of the equinoxes; the directly place shillings and pence in our pockets? This nutation of the earth's axis; the aberration of light; were not only to extinguish a source of the highest the oscillations both of the ocean and the atmosphere, pleasure, but to bury some of the richest talents comand those varitions in the elements of the planetary mitted to our care; and to yield up some of the most motions and orbits, termed secular, requiring in some ennobling impulses of our nature to motives of the most cases the lapse of ages for their development. In all sordid selfishness. I repeat it, that on this fair and elethese instances we have not only seen every anomaly vated ground we might take our stand and vindicate disappear, but each become a striking confirmation of the cultivation of astronomy, though it had not one the law it seemed likely to subvert. Nay, farther, this useful application. law itself has been our most efficient instrument of dis- But a very eminent modern writer has justly remarkcovery. Many varitions in the planetary motions, so ed—“that in every department of natural science, the delicate and refined as to elude the nicest observation, speculations of the philosopher, however remote they have been brought to light, by being first deduced as may for a time lead him from beaten tracks and every mathematical consequences from the general law. Such day uses, being grounded in the realities of nature, instances as these are among the triumphs of science; have all, of necessity, a practical application-nay and we cannot put from us the consideration of them in more, such applications form the very criterions of their an essay on the importance of astronomy. To do so, truth.” were to reject the noblest use of the sublimest of sci. I cannot possibly in the time devoted to this essay,

touch upon more than three or four of the many imporI would here remark, that it is only by viewing as- tant results derived from astronomical science; and even tronomy in this light of stability and perfection, that these but hastily and imperfectly. In doing this, I shall we are prepared to appreciate its value as a branch of be compelled to employed scientific terms to an extent education. Since it is the object of education, as the greater than I wished. As far however as may be, I word itself implies, to unfold the powers of the mind, shall endeavor so to express myself, as to render my and to prepare them to take deep root in any soil se- remarks intelligible to all who retain only so much of lected for their growth; it is of great consequence to in knowledge upon this subject as any elementary treatise troduce into a course of instruction such subjects, as by will furnish. the nature of their principles and the rigor of their In the first place, it ought not to be regarded as a demonstrations, are best adapted to this purpose. Un- small thing, that the cultivation of astronomy has requestionably, the study of morals and the principles of moved the apprehensions and fears which so frequently human action, is at once the most important and digni- seized upon the public mind on the occasion of any refied; but we should err greatly in supposing that one markable phenomenon among the celestial bodies. We can acquire a really philosophical and well balanced have read of whole armies being panic-struck by an mind, without the cultivation of the physical sciences. eclipse of the sun or moon. A delay in evacuating the It is conceded, that they draw most largely upon our island of Sicily on account of an eclipse of the moon, powers of attention, abstraction and combination. It is was the occasion of the death of the Athenian general, said of the great founder of the Pythagorean school, Nicias, and the destruction of his whole army; a loss so that he would receive no pupil who had not attended to ruinous to his country, that it may be stated as the mathematics. He placed an inscription over his door- catastrophe which led to its subversion. Ovdeus ayewpetpatos ciouTW-(Let no one unskilled in ge- Alexander the Great, before the battle of Arbela, ometry enter here."). And this sentiment of the philoso- was so terrified at an eclipse of the moon, as to order pher has been confirmed by the experience of all suc sacrifices to the sun, moon and earth, as the deities ceeding ages : that those studies requiring difficult and which produced these phenomena. In 1686, the astrorefined applications of the mathematics are among nomers of all Europe agreed in announcing a conjuncthose best adapted to the expansion of the intellectual tion of the whole planetary system, which they suppowers:-and at the head of them all, "as the most posed would be accompanied by the most terrible rava. difficult and the best perfected, as embracing a class of ges, and perhaps by the destruction of the world. On phenomena the most various and complicated, and as the occasion of the furious wind and remarkable heat of presenting a generalization the most complete, and a Oct. 20th, 1736, it was announced in the public gazettes final result the most simple, sure, and imposing," stands that the sun had retrograded through several signs; physical astronomy,

and it actually became necessary for the scientific to une Furthermore, man has been constituted a speculative deceive the public mind. It was universally agreed at being. Study is one of the wants of his humanity. the close of 1768 that saturn was lost: and 1773 and He contemplates the world and the objects around him, 1788 were each spoken of and published as the end not with a passive and indifferent gaze, as a set of phe- of the world. (See Astronomie par Lalande.) The nomena in which he has no interest ; but as a system comets especially have been looked upon as objects of which evidently has been contrived for his comfort and terror by all people. They have been supposed to be happiness, and for the exercise of his intellectual pow. ominous, and to shake from their fiery train wars, pesers. It is for this reason, that I regard the pleasure which uilence and famine. Pope Callixtus Il'exorcised a comet science brings to the mind, as a proper and sufficient and the Turks in the same bull. (Delambre.) They motive for its cultivation. And when we have experi- were thought to make their appearance at the birth or enced a curiosity intense and devouring, leading us to death of distinguished men. Justin relates, that at the penetrate into the recondite and beautiful relations of birth of Mithridates, there appeared a comet surpassthe physical world, we can never hear without a feeling ing the sun in brilliancy and occupying one quarter of of humiliation, the question—"to what profit is all the heavens. One, scarcely less remarkable, is said to this ?" Is it not enough, that the Maker of the Universe have appeared at the death of Julius Cæsar, and anohas created all things in wisdom and in goodness—has ther at the birth of Mahomet. And perhaps the fears endowed us with faculties capable of tracing in some of some who now hear me, were but a year or two measure the operations of his skilful hand-and has so since excited by an expected collision between our globe constituted us, that such researches bring to us emo- and the comet of Dr. Halley. These days of superstitions which are among the most pleasurable our exist- tion have either passed or are passing rapidly away. ence furnishes? Shall he have made the sun to rule by All the phenomena relating to eclipses are thoroughly day-the moon by night ;-shall he have drawn out the understood and are susceptible of being precisely predicted. If some obscurity still rests over the nature of brook, are only familiar and particular instances of a comets and their trains, yet we know that they consti- great law extending throughout the universe, and contate one family with the planets. They all 'move in trolling alike the mote which glitters in the sun-beam elliptic orbits; for as to parabolic orbits, we may al- and the planet which sweeps its ample rounds through ways substitute elliptic ones more or less elongated, the regions of space. which will satisfy observations equally as well. Much In the second place, astronomy furnishes us with our less has any orbit been proved to be hyberbolic. This measure of time. We have no adequate means of meabinds all of them to our system as component parts, suring time but by motion; and motion for this purand subjects them to the same dynamical laws which pose must be perfectly uniform. If the force of gragovern all the rest. On account indeed, of the great vitation is always the same at the same place—which is excentricity of their orbits, and the smallness of that not only very probable but susceptible of experimental portion of each which is visible to us, we cannot calcu- proof—it can be mathematically demonstrated, that the late their periodical times with the same precision as in oscillations of a cycloidal pendulum, as well as those of the case of the planets; still the returns of several have a pendulum vibrating in extremely small circular arcs, been determined with sufficient accuracy to warrant the are isocronous. Such a pendulum therefore might furassertion, that if our data could be obtained more pre- nish us a unit of time : yet it would be an objectionable cisely, their periods might in all cases be truly estima- one in several respects. In the first place, there is nothred. In regard to a collision between one of these ing requiring us to adopt a pendulum of one length rathbodies and the earth, it may be shown to be impossible, er than another; the unit of time then would be different so far as the 117 comels whose orbits have been calcu- at different places, unless mankind agreed universally to ted, are concerned. If the perihelian distance exceeds adopt one of the same length. In the second place, should the distance of the earth from the sun, the orbit of the they thus agree, to say nothing of the practical difficulty comet, though in the plane of the ecliptic, must include of making two pendulums of precisely the same length, that of the earth ; so that in this case there canno: pos- these pendulums will not vibrate equally when suspendsibly be a collision. If the perihelian distance be less ed at different points upon the earth's surface. In the than the distance of the earth from the sun, and the or- third place, the oscillation of a pendulum, is a portion bit still in the plane of the ecliptic, there will be two of time too small to serve as a unit. While then the intersections, and consequently iwo chances of encoun- pendulum in the present improved state of its applicater ; but this case is not to be found in nature. All of lion to clocks, is of very essential service in dividing the known orbits are inclined to the ecliptic, and gene-time into minute portions, for the reasons just stated rally at a very considerable angle ; in such a manner, it cannot afford a convenient standard of time. that when the radius vector is equal to that of the earth, Writers on physical astronomy have proved that its latitude is so great, that the comet will pass at a con- among the ever varying elements of the solar system, siderable distance either above or below the earth. But the period of the earth's rotation on its axis is immutaare we bol in danger of being enveloped by one of those ble. Many causes indeed might be conceived to affect Fast luminous appendages extending so many millions the truth of this statement : such as the descent of riof miles? Not at all. The tail is always upon the pro- vers—the ascent of vapors--the projected matter of longation of the radius vector, so that to envelop the volcanoes—the constant friction of the trade windsearth, it is necessary for the comet to be at the same time and the action of the sun, moon and planets, which is in its inferior conjunction and at one of its nodes ; condi. known to be quite considerable in modifying its motion tions difficult to be united, if not wholly incompatible. in its orbit. But not one of these singly, nor all comNeither have we any thing to fear from the perturbing bined, can produce any perceptible effect upon either force of such comets as approach the nearest to us. The the period or the axis of rotation. By this uniform nearest of all was that of 1770, which approached within rotation then, we are furnished with as perfect a stand800,000 leagues; but Dusejour has shown that the ef- ard of time as we could wish. Yet its practical applifects would be inconsiderable at the distance of 13,000 cation is encumbered with some difficulties. If the leagues. And we do certainly know that our astronomi. stars were absolutely fixed, the successive returns of cal tables have needed no corrections on account of the any one of them to the meridian of a place, would mark attraction of comets ; a sufficient proof of the smallness the period of that rotation, and the siderial days would of their nucleus and the extreme tenuity of the matter all be equal among themselves. But there are derang. composing their trains. If additional evidence of this ing causes, variable in their effects, both as to degree fact were required, it is furnished by the comet of 1770; and direction, which render the transits of all the stars which actually became entangled among the satellites unequal, when compared, the one with another. These of Jupiter, and yet produced no perceptible derange- inequalites are indeed extremely small,

and altogether ment in their motions. (Se Astronomie par Delambre, imperceptible in the course of a few days. But still T. III. Ch. 20.)

they exist, and become perceptible in their accumulaFurthermore, chymistry and its kindred sciences tions. If, however, we define a siderial day to be the have been very justly considered important, by reason time of the earth's rotation, although it is not equal of the erroneous impressions they have served to re- precisely

to the interval between the transists of a star, move relative to the constitution of the material world; yet it is a quantity which may be calculated from thai nor has astronomy been less serviceable in this respect. interval, and therefore available as a unit of time. But The stars are no longer believed to preside over the our daily occupations and our seasons of labor and of destinies of men. We consider it of no great conse- rest being regulated by the motion of the sun, it is very quence now-a-days under what aspect of the planets a desirable to adopt its transits as our measure of time, man be born; and the points of the horoscope are instead of those of a fixed star. For if we were to mere objects of curiosity. The sun, planets, and as- reckon the day as commencing at the arrival of any, semblage of fixed stars are no longer linked severally star on the meridian, in the course of a year this arrival to transparent shells, by the revolution of which they would happen when the sun would be at all possible are carried about us in twenty-four hours. The earth angular distances from the same meridian, and conseis no longer the centre of the universe, essentially

en- quently our days so reckoned would be commencing at dowed with immobility and extending indefinitely be different parts of the working day, which is naturally beath and around us : but takes its place as an incon determined by the sun. Hence mankind have univer. siderable satellite to the sun, and by a double motion, sally agreed to make

use of the motion of the sun as a the one on its axis, and the other in its orbit, gives rise standard of time; the returns of which to the same merito the succession of day and night, and the recurrence dian and equinox, constitute the day and the year. But of the seasons. We no longer stand in need of vorti- the solar days

are not equal among themselves, for two ces to explain the celestial motions, but are perfectly reasons: the first is, because the proper motion of the assured that the falling of a leaf, and the running of a sun is unequal, owing to the eccentricity of its orbit ;

« 上一頁繼續 »