we, too, tell their numbers; yea, and call them by their names! But what are those that are named, in comparison with those which our glasses discover? What are two or three thousand, to those we discover in the milky-way alone? How many, then, are there in the whole expanse? But to what end do they serve? To illuminate worlds, and impart light and heat to their several choirs of planets? or to gild the extremities of the solar sphere, and minister to the perpetual circulation of light and spirit?

What are comets? Planets not full formed, or planets destroyed by conflagration or bodies of an wholly different nature, of which we can form no idea. How easy it is, to form a thousand conjectures! how hard to determine any thing concerning them! Can their huge revolutions be even tolerably accounted for, on the principles of gravitation and projection? What brings them back, when they have travelled so immensely far? or what whirls them on, when, reasoning justly on the same powers, they should drop into the solar fire?

What is the sun itself? It is, undoubtedly, the most glorious of all the inanimate creatures: and its use we know. Gon made it to rule the day. It is,

"Of this great world, both eyes and soul."

But who knows of what substance it is composed, or even whether it be solid or fluid? What are the spots on its surface? what its real magnitude? Here is an

unbounded field for conjecture; but what foundation for real knowledge?

What do we know of the feebly-shining bodies, the planets, that move regularly round the sun? Their revolutions we are acquainted with; but who can regularly demonstrate to us either their magnitude, or their distance, unless he assumes it in the usual way, inferring their magnitude from their distance, and the distance from the magnitude. What are Jupiter's belts? What is Saturn's ring? The honest ploughman knows as well, as the most learned

astronomer.

"Sir Isaac Newton certainly discovered more of the dependencies, connexions, and relations of the great system of the universe, than had, previous to his time, been conceded to human penetration: yet, was he forced to bottom all his reasoning on the hypothesis of gravitation; of which he could give no other account, than that it was necessary to the conclusions he rested upon it."

OF THE PRECESSION OF THE EQUINOXES.

The equinoctial points, as have been before explained, are those two opposite points, where the ecliptic and equinoctial cross each other, at the first point of Aries and Libra, and are called the vernal and autumnal equinoxes. By long, and a continual series of observations, it has been observed, that the above two points have a westerly recession, or mo

tion backwards, contrary to the order of the signs of about 50 seconds, yearly, This retrograde motion of the equinoctial points, or the nodes of the earth's orbit, as it has been termed, is called the Precession of the Equinoxes.

The solstitial points, are these two opposite points where the ecliptic touches the tropics, and 90° from the equinoctial points, are consequently subject to the same recession.

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To have a clear idea of this subject, the student must be informed, that astronomers begin the year the spring, when the sun is in that node of the equator, or equinoctial point, called Aries, or at the vernal equinox; and that the time the sun takes in his motion from any one equinoctial point, or tropic, round to the same again, is called the Tropical, or Natural Year; and called by some the Mean Solar Year. Its length, by observation, is found to be 365 5 48′ 49′′.

The time the sun also, by observation, is found to take, in moving from any particular star to the the same star again, is called the Siderial Year; and is fixed at 365 6 9' 12". The siderial year, therefore, exceeds the tropical year by 20 minutes, 23 seconds in time; and consequently the Julian, or Civil Year, which we adopt at 365 days 6 hours, is nearly a mean between the siderial and tropical.

The whole ecliptic of 360° being passed through by the sun in a tropical year, his daily mean motion is about 59' 8"; and for the above difference 20′ 23′′ in time, his motion will be very near 50"; and just

so much of a degree sooner will he arrive at the same equinox, or solstice, than at any star, or fixed point on the heavens, in one annual revolution; so in respect to the fixed stars, will cause the equinoctial points, as well as itself, to recede about 30 degrees in 2160 years, and in the whole circle of the equinoctial, in about 25920 years. This period has been called the Grand Platonic Year.

The receding of the equinoctial points has thus occasioned an apparent advance of the fixed stars in longitude of about 50" per year, and from whence it follows that, since the time of Ptolemy, in the infant state of astronomy, the zodical figures, or constellations, have moved forward about one whole sign, and as shewn upon our New British Celestial Globes, the constellation of Aries, situate in that part of the ecliptic, named Taurus. situation of Gemini, &c.

Taurus, in the Hence, the stars that

rise and set at particular seasons of the year, in the times of Hesiod, Eudoxus, Virgil, Pliny, &c. at the present period, will have a manifest difference in respect to time. It is to the attractive influence of the sun and moon, on the redundant matter in the equatorial regions of the earth, that Sir Isaac Newton, and other astronomers, have asserted to occasion this peculiar slow motion. From the earth's motion on its axis, much more matter is accumulated about the equator, than at any other parts of the globe, and the power of the sun and moon's attraction, is judged to bring the equator quicker under them, than if there were no such accumulation of matter.

The phenomena of the precession, may be more familiarly understood, by the student placing before him a celestial globe : he must bring the pole of the ecliptic to the brazen meridian, and consider both the ecliptic, and its axis, to be immoveable, and the earth's axis, or poles of the equinoctial, to be in motion round the earth's centre, which he may conceive will form a double cone round the axis of the ecliptic, in the time the equinoctial points circumscribe the ecliptic, which is about 25,920 years; and, in that time, the earth's axis will describe a circle in the heavens, round the pole of the ecliptic, which is stationary on that circle, the earth's axis being inclined 23 degrees to that of the ecliptic: the circle described by the north pole, will be 47 degrees in diameter, twice that of the inclination of the earth's axis. Consequently, that point in the heavens, which is now the north pole, and very near to the polar star, as it is called, which is in the tail of Ursa Minor, will be receded from by the earth's axis, at the rate of about 1 degree in 72 years. And, in 12,960 years, will be directed to some other star in the heavens, diametrically opposite in the circle, on the other side of the pole of the ecliptic; and the north pole of the heavens will then be in a situation 8 degrees south of the zenith of London, which is at 51 North. The places, also, of the equator and two tropics, will be very materially changed. And the sun in the same part of the heavens, where he' now covers the earthly tropics, and makes the shortest days, and longest nights, in the northern hemisphere;

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