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ginary and fallacious, and, therefore, all his mathematical diagrams and ratios, grounded thereon, are false and delusive.”
It does not appear that Mr. Prescot has any objection to the mathematical calculations of the astronomers whom he opposes; but he levels his attack upon their hypothetical data. If their premises were correct, he would evidently admit their inferences; but he stoutly denies that the experiments from which they reason were applicable to the subject. Thus, he says
“We are, however, assured that Mr. Huygens, the mathematician, demonstrated, * by the vibrations of a pendulum, that all bodies on, or near the surface of the earth, in their fall, descend so as that at the end of the first second of time they have described sixteen feet, one inch, and acquired a velocity of thirty-two feet.' I have examined the rule from which he makes this deduction, but I confess I am not able to discover any just comparison between the motion of a vibrating pendulous body, and a body detached in the act of falling to the earth : the respective motions are so completely distinct, that I am well satisfied no geometrical reasoning can ascertain the velocity of the one from the motion of the other, But the theory supposes what is impossible ; namely, that these experiments be performed in an unresisting medium, such as Newton means by what he terms, the æthereal regions, which have never been proved to have an existence except in the heads of pbisophers. It is a question that cannot be decided in a space so confined as the receiver of an air-pump, even if could be completely exhausted of the air, which is impossible.”
He afterwards proceeds to observe, that
** The operation of that which gives weight to bodies, is evideptly limited to the surface of the earth, or within a short distance of it. An illiterate miner once informed me, that it was commonly observed by the men with whom he laboured, that they could lift a greater weight in the works below than upon the surface of the ground above. The same remark I find in Lord Bacon's Natural History.
It is,' says he, affirmed constantly by many, as an usual experiment, that a lump of ore at the bottom of a mine will be tumbled and stirred by two men's strength, which if you bring to the top of the earth will require six men's strength at the least to stir it; it is a noble instance, and is fit to be tried to the full ; for it is very probable, that the motion of gravity worketh weakly, both far from the earth, and also within the earth,—the former, because the appetite of union of deose bodies with the earth in respect of the distance is more dull,the latter, because the body hath in part attained its nature when it is some depth in the earth. For, as for the moving to a point or place, which was the opinion of the ancients, it is a mere vanity.' The
* This word, though very properly applied by Euclid, is grossly prostituted by modern philosophers.
facility of moving heavy bodies io mines was likewise noticed by the ancients in the pits whence they drew the sal.ammoniac in Egypt; but they erroneously supposed it to be owing to the buoyancy of subterraneous vapours.
These accounts alone, if founded in fact, are, I think, decisive against the theory of gravity; for, according to that hypothesis, the difference of a few hundred, or of even a few ousand, yards of ascent, or descent, could produce no sensible alteration in the weights of bodies."
On the subject of Attraction, astronomers hold that all bodies are mutually heavy, or gravitate mutually towards each other, and this gravity is proportionate to the quantity of matter; and at unequal distances it is inversely as the square of the distance, and so the sun and planets mutually gravitate towards each other. To prove this property in matter, they say, “ Action and Reaction are always equal and in contrary directions. If a stone be pressed by the finger, the finger is equally pressed by the stone: if a horse draws a stone, the stone draws the horse equally backward; for the rope is equally stretched towards both.”
Mr. Prescot objects to this illustration as inconclusive, because in the one there is a visible connexion, but not in the other : the medium, or rope, by which the sun and planet mutually draw each other, is assumed, and no distinction is drawn between the inert matter of the stone, and the principle of animal life which actuates the horse ; and Mr. Prescot demands,“ Is there any force unconnected with spirit.2"
To the experiments which have been made to explain or prove the revolutions of the primary and secondary planets and comets, our author, also, very confidently opposes himself. He ridicules the whirling a ball round the finger, and tying a pebble to a mill-stone. Such“ experimental” proofs are, he says, very little to the purpose. He then proceeds
66 This doctrine of mutual attraction, had it any real existence, would be utterly subversive of the system ; suppose, for example, Jupiter and Saturn to be posited in the same point of the heaven,I mean with respect to their heliocentric longitude,—and that Jupiter by the powerful attractive force ascribed to Saturn, is disturbed and drawn out of the orbit which he would otherwise describe, according to the doctrine of centripetal forces; how, in such case, would Jupiter regain his proper course? For, if the action of Saturn could attract him a single mile, that action would then be increased, and would continue to increase, according to the doctrine of philosophers, in the reciprocal duplicate proportion, while, at the same time, the power which should have retained Jupiter in his orbit decreases in the same proportion." It
may be important also to observe, that Newton believed
the sun to be a body of fire; but this opinion has long been generally abandoned, and the sun is now supposed to be a body of earth with a luminous atmosphere. The subject is open to the observation of our author, that, as it is impossible that a body of fire and of earth can be of the same density, the system of gravity which had so strangely mistaken the nature of the central body cannot be depended upon.
It appears, that the only sensible or vulgar evidence we have of the mutual gravitation of the celestial bodies, is the operation of the moon upon the tides. Our author has industriously applied himself to falsify the fact which has been asserted.
66 The Newtonians (says Mr. Prescot) assure us, that 'the sun's influence in raising the tides is but small in comparison of the moon's; for though the earth's diameter bears a considerable proportion to its distance from the moon, it is next to nothing when compared to its distance from the sun; and, therefore, the moon must raise the tides much higher than they can be raised by the sun.””
On this our author observes, that his opponents are at variance with their own laws-namely, the attraction in proportion to the respective quantities of matter.
“According to their creed, the sun is 64,000,000 times greater than that of the moon, and his distance from the earth is four hundred times greater. The square of four hundred is 160,000; therefore the sun's attraction of the earth, supposing his mass to be equal to that of the moon, would be 160,000 times weaker than the moon's attraction; or, in other words, the mass of the sun, at the distance they place him, in order to possess on the surface of the earth an attraction equal to the moon's, ought to be 160,000 times greater than the moon : but, according to Newton, the density of the sun to that of the moon, is as 4891 to 1000: its mass of matter would, in that case, be to the mass of matter in the moon, as 13,085,259 to 1. But it is said that the distance of the sun is four hundred tiines greater than that of the moon: therefore the effect of the solar gravity on the tides compared with the lunar gravity, would be as 13,085,259 to 160,000; or as 82 to 1. We are, notwithstanding, very gravely told, that its effect in raising the tides is no more than a fourth or fifth of the moon's attraction; that is to say, about four hundred times less than it ought to be according to the unerring principles of gravity! But mark their further reasoning upon this point, • It is owing to the sun's immense size and distance, but the moon, because her distance in comparison 10 that of the sun from the earth, is very small, the forces with which she acts on different parts of the earth will vary more considerably from parallelism and equality.'
“ This curious sophistry is, as I said, an evasion of their own boasted theory of gravity. It is a very important point, and they cannot pos. sibly get over it. The aspect, or angle of apparent magnitude, is very nearly the same in both luminaries; and the question here, is not concerning the effect of attraction upon a homogeneal body, but
In a space
upon one composed of earth and water; and however the eartby parts might, or might not, be affected, it is very certain that the light, moveable, watery parts, by being acted upon by a force eighty-two times greater than that of the moon, would inevitably communicate such an amazing agitation to the ocean as would quite absorb and render imperceptible the comparatively weak effect of the moon's attraction; and also render the ocean completely unfit for the purposes of navigation. But nothing of the kind is experienced, and consequently the whole theory of gravity is imaginary and false.
It is also maintained, that the actual observations which have been made on the state of the ocean, are directly at variance with the results of these calculations.
66 The great Pacific Oceau is, of all other parts of the globe, the most proper for examining the validity of Newton's theory of the tides; for, there the operation of the moon, supposing his hypothesis to be well grounded, would not be obstructed by head-lands, bays, gulfs, &c.
of many thousands of miles, in every direction, there is nothing to interfere with the movements of this mighty ocean, excepting a few insignificant islands just rising here and there above the surface, which, comparatively, no more obstruct its motions than the nilometer does the overflowings of the river Nile. How then does theory agree with observation there? Mr. Wales, the astronomer, who accompanied Cook, tells us: his words are—' in these observations some very curious and even unexpected circunstauces have offered themselves to our consideration. It will be sufficient to instance the exceedingly small height to which the tide rises in the middle of the great Pacific Ocean; where it falls short two-thirds at least of what might have been expected from theory and calculation.'
“ Cook says, that the tides at the Sandwich Islands are 'so inconsiderable, that it is hardly possible at any time to tell whether they had high or low water; or whether the sea ebbed or flowed. At Van Diemen's Land, he found the perpendicular rise to be eighteen inches; and it never appeared to have exceeded thirty inches. At the Friendly Isles, he observed, it was only in the channels and a few places near the shore that the motion of the tide was perceivable; it rose from three to six feet, which was the most considerable elevation that he had met with in that ocean between the Tropics. At Otaheite it was proved that the tides never rose higher than fourteen inches at most; and that it was high water nearly at noon, as well at the quadratures as at the full and change of the moon.'"*
We are further reminded, as a proof that the moon does not govern the motion of the waters, that the current in the Mediterranean continually sets into the Straits in a direction exactly contrary to the moon's diurnal motion. The Euripus, between the Black and Mediterranean Seas, during certain days every moon, ebbs and flows seven to nine times in twentyfour hours. At Tonking, on the coast of China, there is only one flux and one reflux in twenty-four hours. That tidetables are constructed from observation, and not from any astronomical calculations. The following candid remarks are taken from the Encyclopædia Britannica :
* This sufficiently refutes the Newtonian assertion, that, “ High water takes place about three hours after the moon passes the meridian." In Liverpool, where I reside, it is high water, generally, about half an hour before the moon passes the meridian. At Plymouth, six hours after; Isle of Wight, nine hours after; and at London, fifteen hours after the moon bas passed the meridian. The time differs every where.
“ The reader will undoubtedly be making some remarks in his own mind of the deductions from this theory with the actual state of things. He will find some considerable resemblances; but he will also find such great differences, as will make him very doubtful of its justness. In very few places does the bigh water happen within three quarters of an hour of the moon's sontbing, as the theory leads him to expect; and in no place whatever does the (highest) spring-lide fall on the day of new and full moon, nor the (lowest) neap tide on the day of her quadrature. These always happen two or three days later. By comparing the differences of high water, and the moon's southing, in different places, he will hardly find any conuecting principle.”
In the chapter on Comets it is insisted that the forms of the orbits, assigned by Newton, are quite incompatible with any known laws of motion and attraction on the earth.
“ He says, the sun's action upon bodies diminishes, and that, consequently, their gravities are less, in proportion as they recede from himn; or, in other words, the matter contained iu that body which revolves in the orbit nearest to him, is more powerfully attracted, and therefore heavier, than bodies performing their revolutions in orbits more distant from him. In conformity with this reasoning he asserts, that on a comet's approach to the sun, its motion is accelerated; and that when it recedes from that luminary, its motion is in a similar degree retarded, that is, in the reciprocal duplicate proportion. If we calculate by this rule and admit, as Sir Isaac asserted, that the comet of 1680, when in its perihelion, or nearest approach to the sun, was within 150,000 miles of him, namely, a sixth part of his diameter; and that in its aphelion, or that end of its orbit most distant from the sun, it was not less than 11,200,000,000 of miles, we shall fiud that the sun's attractive power upon it is above 5,500,000,000 times greater in the former than in the latter situation, By what miraculous law of motion then could the comet, being so powerfully acted upon, quit the neighbourhood of the sun?
Dr. Halley had predicted the return of a comet in 1758. Towards the end of that year, when it had not made its appearance, other calculators extended the time to the middle of April, 1759.
“The theory, then, required that this comet should appear about that time. But to whom did it appear? Why, truly, we are told, by La Place, that Clairault had the satisfaction of seeing his prediction accomplished on the 12th of March, 1759. On looking into