,,i INTRODUCTORY DISCOURSE OF THE 



by the earth, aud tha earth by the sun, the inoon U also drawn directly by the sun ; and while Jupiter is 

 drawn by the sun, so are hi* moons; and both Jupiter and his moons are drawn by Saturn: nay, as 

 this power of gravitation is quit* universal, and as no body can attract or draw another without being 

 iUelf drawn by that other, the earth is drawn by the moon, while the moon is drawn by the earth ; and the 

 sun i attracted by the planets which he draws towards himself. These mutual attractions give rise to 

 many deviations from the simple line of the ellipse, and produce many irregularities iu the simple calculation 

 of the times and motions of the bodies that compose the system of the universe. But the extraordinary 

 powers of investigation applied to the subject by the modern improvements iu mathematics, have enabled 

 ui at length to reduce even the greatest of the irregularities to order and system, and to unfold one of 

 the most wonderful truths in all sciences; namely, that by certain necessary consequence of the simple fact 

 upon which the whole fabric rests, the proportion of the attractive force to the distances at which it 

 operates, all the irregularities which at first seemed to disturb the order of the system, and to make the 

 appearances depart from the doctrine, are themselves subject to a certain fixed rule, and can never go beyond 

 a particular point, but must begin to lessen when they have slowly reached that point, and must then lessen 

 until they reach another point, when they begin again to increase ; and so on, for ever. Nay, so perfect ia 

 the arrangement of the whole system, aud so accurately does it depend upon mathematical principles, that 

 irregularities, or rather apparent deviations, have been discovered by mathematical reasoning before 

 astronomers had observed them, and then their existence has been ascertained by observation, and found to 

 agree precisely with the results of calculation.* Thus, the planets move in ovals, from gravity, the power 

 that attracts them towards the sun, combined with the original impulse they received forwards ; and the 

 disturbing forces are continually varying the course of the curves or ovals, making them bulge out in the 

 middle, as it were, on the sides, though in a very small proportion to the whole length of the ellipse. The 

 oral thus bulging, its breadth increases by a very small quantity yearly and daily ; and after a certain large 

 number of years, the bulging becomes as great as it ever can be : then the alteration takes a contrary 

 direction, aud the curve gradually flattens as it had bulged ; till, in the same number of years which it took 

 to bulge, it becomes as flat as it ever can be, aud then it begins to bulge again, and so on for ever. And so, 

 too, of every other disturbance and irregularity in the system : what at first appears to be some departure 

 from the rule, when more fully examined, turns out to be only a consequence of it, or the result of a more 

 general arrangement springing from the principle of gravitation ; an arrangement of which the rule itself, 

 and the apparent or supposed exception, both form parts. 



The power of gravitation, which thus regulates the whole system of the universe, is found to rule each 

 member or branch of it separately. Thus, it is demonstrated that the tides of the ocean are caused by the 

 gravitation which attracts the water towards the sun and moon ; and the figure both of our earth and of such 

 of the other bodies as have a spinning motion round their axis, is determined by gravitation combined 

 with that motion ; they are all flattened towards the ends of the axis they spin upon, and bulge out towards 

 the middle. 



The great discoverer of the principle on which all these truths rest, Sir Isaac Newton, certainly by far 

 the most extraordinary man that ever lived, concluded by reasoning upon the nature of motion and 

 matter, that this flattening must take place in our globe : every one before his time had believed the earth 

 to be a perfect sphere or globe, chiefly from observing the round shadow which it casts on the moon in 



-es ; and it was many years after his death that the accuracy of his opinion was proved by measure- 

 ments on the earth's surface, and by the different weight and attraction of bodies at the equator, where 

 it bulges, and at the poles, where it is flattened. The improvement of telescopes has enabled us to 

 ascertain the same fact with respect to the planets Jupiter and Saturn. 



Besides unfolding the general laws which regulate the motions and figures of the heavenly bodies 

 forming our Solar System, Astronomy consists iu calculations of the places, times, and eclipses of those 

 bodies, and their moons or tatelUte* (from a Latin word signifying an attendant), and in observations of the 

 Fixed Stars, which are innumerable assemblages of bodies, not moving round the Sun as our Earth aud 

 the other planeU do, nor receiving the light they shine with, from his light ; but shining, as the Sun and 

 the Comets do, with a light of their own, aud placed, to all appearance, immovable, at immense distances 

 fn.m our world, that is, from our Solar System. Each of them is probably the sun of some other system 

 like our own, composed of planets and their moons or satellites ; but so extremely distant from us, that they 

 all are teen by us like one point of faint light, as you see two lamps placed a few inches asunder, only like 

 one, when you view them a great way off. The number of the fixed Stars is prodigious: even to the 

 naked eye they are very numerous, about 3,000 being thus visible ; but when the heavens are viewed 

 through the telescope, stars become visible in numbers wholly incalculable : '2,000 are discovered in one of 



The .pi.lic.tion of rn.thrm.lic. to chemistry has .ImHy produced a great change in that science, and is calculated to 

 produce Mill greater improvement*. It may be almoit certainly reckoned upon aa the source of new discoveries made by 

 indurtion after the mathematical reuoning has gien the suggestion. The learned reader will perceive that we allude to the 

 beautiful doctrine of ttrftnilt or UfUipIt Proportion!. To take an example; the probability of an oiide of arsenic being 

 disarmed U improved upon as. bjr the composition of anenious and arsenic acids, in which the oxygen it as 2 to 3 j and therefore 

 w m.y eipwt to flnd a compound of the same base, with the oxygen as unity. The extraordinary action of chlorine and iu 

 1 1 oo bfbt.lead* us to expect some further discovery respecting its composition, perhaps respecting the matter of light 



