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Thefe circumftances must be reverfed in the fouthern hemifphere, fuppofed as before; I fay, it would be deprived of the folar rays, or enjoy them for a very little time; during which time they would fall very obliquely, and confequently be reflected through the atmosphere, fo as to fly off without farther effect.

If we fuppofe a dozen of precifely fuch earths fo fituated, extended in a line laterally by each other, they would be all alike, and all fixed as to their feafons :' but if we fuppofe them placed in a circle round the fun, the cafe is inftantly altered; if to one it was fummer in the north, to its oppofite it would be fummer in the fouth; if to one it was fpring in the north, to its oppofite it would be autumn in that hemifphere: this contrariety would be regular throughout all the oppofites. We have only to place a fingle globe fucceffively in the places of these twelve fuppofed globes, and the idea is rendered perfpicuous, and facile; we fee at once, that what was formerly moft directly turned to the fun, is now turned from him; and what was formerly denied his beams, now enjoys them in profufe abundance: fuch effects arife from the inclination of the earth to the plane of its orbit.

The axis of the earth (or its inclination) is fixed, is constantly the fame, points to the fame place in the heavens; but its furface is ever in motion, and from hence arife other changes, which have no relation to the feafons. The furface of the earth is ever in motion, rolling fteadily from weft to east, with unperceived gradation; yet not the lefs real because unperceived. By this rotation of the earth, thofe bodies which are too distant to move with it seem to move contrarywife, from east

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to weft. Do you afk why we do not feel this motion? I reply, we are too diminutive :- I ask, in return, what proportion a man of fix feet bears to (four thousand miles) the femidiameter of the earth? and I refer you to confiderations and proofs that it must be fo, whatever be our feelings on the occafion Is it credible that we difcern the operations of nature, fo as to trust to the judgment of our feelings, or our fenfes ? And what good reason can be given, that the diurnal motion we obferve in the heavenly bodies fhould not as well (much rather) originate in our own globe than in the heavens, notwithstanding appearances?-But for proofs of the fact, take the following hints; firft, wish to affert, that our fenfes are not competent judges of any occurrences not neceffary to human life, to which they are more immediately adapted, and for which they are conftructed and appointed; fecondly, That in many respects they deceive us in fubjects nearly related to human life itself; if they be presented to us diverfe from what we are accustomed to. Our faculty of judgment connects fo many things together to form a determination, that it eafily errs if any of those things be varied. How badly fome perfons judge of distance! A countryman thinks a street in town a very different length from what it is: as a townfman thinks a mile in the country a dreary space indeed! and fo tirefome! though he walks half a dozen in a day among the bustle of London without fatigue. How exceedingly have all of us occafionally varied in our judgment of the progress of time! When pain has afflicted us, how flowly he moves! every moment is an hour! But when the sprightly dance exhilarates our fpirits, the morn

ing may furprife us ere we think it night. We judge of all things by comparison like thofe who, defcending from the frozen fummit of a mountain, bathe themselves in a stream at midway, that they may enjoy the grateful warmth; from which grateful warmth, as exceffive cold, fhrink back those afcending from ardent plains below. The progreffive motion of a ship under easy fail is not felt by those on board; no, the land recedes and difappears; to a man fitting in a windmill, while it moves round the poft in the middle, the post seems to move. But why fhould I refer to these things, though well known, and undeniable, when we have fo lately proved the fallacy of appearances in the motions of the planets: they are really always direct, yet fometimes they appear retrograde; they are conftant in motion, yet fometimes feem to stand still. Let us then acknowledge, that it may be that the fun does not daily go round the earth, but that the earth goes actually round its own axis, and thereby turns fucceflively every part of its furface to the fun this granted, we must never forget, that the apparent motion is always contrary to the real; that in the morning the part whereon we stand moves toward the eaft, i. e. (we looking fouth) from our right to our left: we may call this toward the fun (i. e. toward the feat of the fun, as termed in perfpective), we advance more eafterly till noon, when we are directly oppofed to the fun, and nearer him by half the diameter of the earth; from noon, we decline from him, ftill moving eafterly, and he feems to decline to the weft: at length, the rotundity of that part of the earth which has fucceeded to our former pofition, totally conceals him from

our

our view, till the rotation of the globe again prefents him in an oppofite part from that wherein we laft faw him.

If the earth had no diurnal rotation, it would be unlike its neighbour planets, for they have: the heavenly bodies, diftant, large, and ponderous as they are, muft move around the earth with a rapidity beyond all measurement: infufferable rapidity! enough, I verily think, to throw them into disorder, and to destroy the balance of attraction among them. And for what benefit?-none to us: fhall all thofe luminous, those magnificent orbs merely roll round us? fo many large objects attend on one small! The thought is unworthy a wife man; fuperior intelligences would blush at the fuggestion.

From the concurrence of these two principles, (1) that the earth circulates round the fun, and (2) that it revolves on its own axis, feveral circumftances arife, which I proceed now to mention. It is evident, that to fome part or other of the globe, the fun muft be vertical conftantly (making noon); but as the earth expofes progreffively its polar parts to the fun, the verticity of the fun changes place. Imagine him first to be vertical at the equator (exactly at the LINE, or mid earth), from whence he proceeds northward, if you pleafe, daily changing his vertical station till he arrives at twenty-three degrees and a half, north latitude; here he ftops: for no fooner has he arrived at this ftation, than the fame caufe which gave him this apparent height of latitude (the courfe of the earth around him), promotes his return to his former ftation, the equator; which paffing, he now inclines as much to the fouth, as before he did to the north,

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i. e. twenty-three degrees and a half. This apparent course of the fun is wholly owing to the inclination of the earth: if the earth was inclined thirty or forty degrees, fo many degrees would the fun appear to advance and to recede. I think it very natural to distinguish that part of the earth, which lies thus expofed to the direct rays of the fun: it is well termed the TORRID ZONE; expreffive of its conftant heat. The extremes of this course of the fun are called TROPICS; the northern, the Tropic of Cancer; the fouthern, the Tropic of Capricorn; because the fun is in thofe figns when in their respective tropics.

It remains to be observed, that, at each tropic, the courfe of the fun feems for a few days not to vary; but although he actually advances or recedes, yet it is not perceptible without accurate observation; this, together with his never exceeding thefe limits, has given occafion to term them fun-ftations, (folis ftatio) or SOLSTICES: the fummer folftice being when this great luminary feems to us highest in the heavens; the winter folftice, when he is loweft: the medium is termed equal night and day (Equinox, equal night); which then obtains throughout the globe. This is clear enough; at the summer folftice we have long days and short nights; at the equinox, day and night are each twelve hours; at the winter folftice, long nights and fhort days.

By the tropics, we have diftinguished a band on the middle furface of the earth, of twice twenty-three degrees and a half in breadth; where the fun is directly over the heads of the inhabitants, where he fheds his rays moft immediately, most vi

gorously