This motion of the earth round its axis, which, from the instances already given, has been rendered sufficiently evident, is called its diurnal, or daily motion; and is that which occasions the regular return of day and night, and all the celestial appearances before mentioned. But there is also another motion of the earth, called its annual, or yearly motion, which occasions the various vicissitudes of the seasons, summer, winter, spring, and

autumn.

And the proofs of this second motion may be easily gathered from celestial appearances, in nearly the same manner as the former. For as the sun seems to move round the earth, from east to west, in the space of a day, which is really owing to the diurnal rotation of the earth upon its axis, in a contrary direction, so, likewise, he seems to have an annual motion in the heavens, and to rise and set continually in different parts of them; which is certainly occasioned by the daily motion of the earth in its orbit, or path round that luminary, which it completes in the space of a year.

That the earth, indeed, is not the centre of the

became better understood, it was perceived, that a body dropped from the top of a tower, instead of being left behind, or falling to the westward of it, ought to be carried forward, and fall to the eastward, in consequence of the centrifugal force being something greater at the top of the tower than at the bottom; and from several accurate experiments this has been found to be the case. Thus a circumstance which was brought forward to refute this doctrine, might now, if necessary, be advanced as a demonstration in support of it.

celestial motions, may be easily shown from the revolutions and appearances of the different planets which belong to our system. For it is certain, that wherever the sun may be placed, the orbit of Venus surrounds and incloses him within itself; and therefore Venus, whilst she describes this orbit, must really move round the sun. For this planet is observed to be sometimes above, or beyond the sun; and sometimes below him, or between the sun and us: but she was never known to come in opposition to the sun, or to be seen in the east when he was in the west; which must necessarily have happened, if she had performed her revolution round the earth, in an orbit like that of the moon.

In like manner, Mercury is always found to keep in the neighbourhood of the sun, without ever receding from him so far as Venus; but as he is continually involved in the splendor of the sun's rays, he can seldom be seen without the assistance of a telescope. The superior brightness of this planet affords, likewise, a sufficient proof, that he must be much nearer to the sun than any of the rest; from both of which circumstances it is evident, that the orbit of Mercury is included within the orbit of Venus, and that, like that planet, he regards the sun as the centre of his motion.

Mars, Vesta, Juno, Pallas, Ceres, Jupiter, Saturn, and the Georgium Sidus, being superior planets, must necessarily include the earth in their orbits; but from their various elongations, or distances from the sun at different times, as well as

from their stationary and retrograde appearances, it is plain that the sun, and not the earth, must also be the centre of their motions, or the body round which they perform their respective revolutions.

Hence it appears, that the earth itself must likewise move round the sun. For since, by the place it obtains in the system, it has those moveable bodies Mercury and Venus on one side, nearer to the sun, and Mars, and the other superior planets on the other side, more remote, it follows, from. analogy, that, being of the same nature as they are, it must also partake of the same sort of motions. And as the earth is placed between Venus and Mars, so the period likewise in which it performs its course round the sun, is a mean between the periods of those planets, being greater than the one, and less than the other, as would naturally follow from such a motion.

The absurdity, indeed, of supposing the earth a sedentary and immoveable body, is sufficiently exposed in the following speech of Adam to the angel Raphael, when he is enquiring concerning the nature of the celestial motions:

"When I behold this goodly frame, this world
Of heav'n and earth consisting, and compute
Their magnitudes, this earth, a spot, a grain,
An atom, with the firmament compared
And all her number'd stars, that seem to roll
Spaces incomprehensible (for such
Their distance argues, and their swift return
Diurnal) merely to officiate light

Round this opacous earth, this punctual spot,
One day and night; in all their vast survey

Useless besides; reasoning I oft admire

How Nature, wise and frugal, could commit
Such disproportions.".

MILTON.

Many other proofs might also be given, which establish this doctrine upon the surest foundation, and secure the abettors of it from all possibility of contradiction. But in a thing which admits of absolute certainty, there have been those who were so perversely ignorant as to refuse all conviction. This opinion of the motion of the earth, like that of its figure, has met with continual opposition; and its advocates have been branded with the most ignominious titles, and persecuted with all the rage of fanaticism.

The celebrated Aristarchus of Samos, for defending this doctrine, was brought before the bench of the Areopagites, and accused, by his adversary, of having violated the laws of religion and morality. And, little more than two hundred years since, the great Galileo met with the same fate. He was summoned before the tribunal of the inquisition, and obliged solemnly to abjure his astronomical tenets; that the sun was immoveable, in the midst of the universe, and that the earth revolved round it as its proper centre. With which requisition he was forced to comply; and to declare that he did with a sincere heart, and faith unfeigned, abjure, curse and detest, these errors and heresies.

Such are the obstructions that have been constantly thrown in the way of science and knowledge. But, happily for mankind, the persecuting spirit of

bigotry and enthusiasm is now losing ground; and the dogmas of papal authority, are as little regarded as the infallibility of its decisions. Philosophers, of every country, embrace the doctrine of Galileo, and are no longer subject to the arbitrary control of monks and inquisitors. That furious spirit of despotism and intolerance which has long held an usurped dominion over the powers of the mind, as well as those of the body, is at length giving way to a more refined polity; and the friends of mankind have reason to hope, that the time is not far off, when the greater part of Europe will be suffered to enjoy, in quiet, that freedom of opinion, both in religion and the sciences, which is the birthright privilege of every human being.