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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 :—

"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 high water happen within three-quarters of an hour of the moon's southing, as the theory leads him to expect; and in no place whatever does the (highest) spring-tide 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 him; or, in other words, the matter contained in 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 find 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

Philosophical Transactions of that year, I find it stated that two mathematicians, a Mr. Munckley, of Lincoln's Inn; and a Mr. Bevis, saw a comet on the 30th of April in that year; and on two or three evenings afterwards, near the horizon in the south; one of the accounts is not quite clear as to whether it had a tail or not; it states, that it appeared to him to be rather surrounded with a circular haziness than a tail. The other saw a tail on the 1st of May, but not afterwards; though La Place says, that the same comet in the year 1456 had a long tail, which spread consternation over all Europe! The commencement of Mr. Bevis's letter is rather curious; he says, 'I had acquainted some of my friends, that it was my opinion a comet would hardly rise above our horizon of London, Sunday, April the 29th; but that probably we might see one on April 30th.' Wonderful to tell, he says he accordingly did see one on Monday! Who, or what, could have put him in possession of the secret? The first time both these gentlemen saw it, was on the same evening; and the comet having answered the important purpose of fulfilling the predictions of Halley, Clairault, and Bevis, it quickly retired, without, I believe, ever having once been seen by the people of either England or France."

We arrive next at the chapter on the supposed diurnal motion of the earth. Mr. Prescot ludicrously states, that this belief is founded only on the experiments of a spindle and soft ball of clay, iron hoop, mop, pendulum, and measurements of a degree of the earth!

The theory which is here attacked, maintains that the earth is of an oblate form, which necessarily results from the centrifugal motion, and by way of EXPERIMENT, (says Mr. Prescot) they

"Stick a spindle through the centre of a soft ball of clay, and by spinning it briskly, they observe that the clay has a tendency to contract at the poles, and fly off the spindle! A certain astronomical professor exhibits the same effects by a thin iron hoop and a rod. That this,' says he, must be the consequence, appears from this experiment; that if you take a thin iron hoop and make it revolve swiftly about one of its diameters, that diameter will be diminished, and the diameter which is perpendicular to it will be increased; now if we suppose the earth to revolve, the parts most distant from its axis must, from their greater velocity, have a greater tendency to fly off from the axis, and, therefore, that diameter which is perpendicular to the axis, must be increased.' Another admired author says, the same doctrine is proved by a mop! When a mop,' says he, is turned upon the arm by a quick circular motion, the threads or thrums are observed to rise highest in the middle, and the swifter the mop is whirled, the greater will be the force, and the particles will fly off with the greater velocity.'"

"The earth has no iron axis stuck through its poles, nor any other kind of axis from which its parts can recede, and therefore your experiment is quite inapplicable. But even were it otherwise, the manifest effect of a centrifugal force, operating with an impulse according to

the experiment, and the theory founded upon it by Newton, would be instant destruction to the globe: because if, by a revolution in twenty-four hours, or in any other given time, that force could so far exceed the power of gravity, as to protuberate seventeen miles on the equator, I cannot conceive any thing to prevent it from rapidly increasing; for, according to theory, the gravity of the equatorial parts would decrease as those parts swelled out: and the diurnal motion continuing the same, the motion of the equatorial parts would increase by a uniform acceleration, until the whole would separate, and fly away from the centre. I remember, when I was at a pottery, that in the process of forming a vessel upon the wheel; suppose globular, or egg-shaped; if the rapid motion of the spindle overbalanced the cohesive temper of the clay, and thereby forced the forming vessel to swell out beyond its prescribed gauge, a continuance of the same velocity of motion would continue to increase its diameter, until it suddenly burst, and flew off the wheel in pieces. As therefore the globe is not so affected in the least, it is sufficiently manifest that the theory is false."

Another experimental proof was derived from the unequal vibrations of the pendulum, which it was asserted beat slower at the equator than nearer to the poles.

"Messrs. Picart and De la Hire, however, instead of ascribing the alterations in the vibration to the force of more, or less, gravity, produced experiments to prove, that the observed effects might possibly be caused by an increase of heat, in the torrid zone, lengthening the rods, and consequently lengthening the vibrations; or by cold producing the contrary effects.

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"When I formerly wrote upon this subject, I expressed an opinion, that the increased density of the air, on approaching towards the poles, would more naturally account for the irregularity of the pendulum's motion, than the fancied distortion of the globe. Since then, on looking into the Philosophical Transactions, I find something like a confirmation of that opinion in the account there recorded of Dr. Derham's experiments. In treating of the figure of the earth, he seems to have paid no regard to the pretended experiments of the pendulum under the equator; For,' says he, 'I have shewn' (No. 294, Phil. Trans.) from the like variations in the air-pump, that this may arise from the rarity of the air there more than here.' And in No. 480, the same writer is more particular; relating some experiments he had made on pendulums vibrating in an exhausted receiver, he observed, that the arches of vibration, in vacuo, were larger than in the open air, or in the receiver before it was exhausted that the enlargement or diminution of the arches of vibration, were constantly proportional to the quantity of air, or rarity or density of it, which was left in the receiver of the air-pump. And as the vibrations were larger or shorter, so the times were accordingly viz two seconds in an hour when the vibrations were largest, and less and less as the air was re-admitted, and the vibrations shortened.' 'Hence,'

VOL. I. PART II.

I I

says Mr. Stone, the resistance of the air must certainly be a considerable obstacle to the equable going of a clock.'”

Kepler and Cassini were of opinion, that the earth was of an oval or egg form. To this was opposed the centrifugal forces of the Newtonian theory. Louis XIV. in honor of his subjects, ordered the whole arc of the meridian passing through France to be measured, and afterwards sent philosophers to the northern and southern parts of the earth. The difference appears to be one inch in twenty feet. Our author is very sceptical in the result.

"How far so small a difference (says he) could be certainly ascertained under the pitiable circumstances in which these poor frost-bitten mathematicians were placed, let the reader candidly judge from the account given by the French; whether the Swedes were more comfortably circumstanced I am not informed.

"In measuring the base line," says Maupertius, "we separated into two bands, each of which carried four rods of fir, each thirty feet long. I shall say nothing of the fatigues and dangers of this operation. Judge what it must be, to walk in snow two feet deep, with heavy poles in our hands, which we were obliged to be continually laying on the snow and lifting again: in a cold so excessive, that whenever we could taste a little brandy, (the only thing that could be kept liquid,) our tongues and lips froze to the cup and came away bloody; in a cold that congealed the fingers of some us, and threatened us with still more dismal accidents; while the extremities of our bodies were thus freezing, the rest, through excessive toil, was bathed in sweat."

"The philosophers who travelled to the south, had, if possible, still greater difficulties to encounter. When placed upon the high mountains, making their observations, besides experiencing excessive cold, they were sometimes in such danger of being blown down the precipices, that even their Indian attendants were frightened away from them. In these dreary and alarming situations, both companies had to measure their base lines;—their terrestrial and celestial angles: -afterwards to try to reduce their measures to the level of the sea! And with all these extraordinary difficulties to surmount, they gravely professed to have discovered, that a degree under the equator, or at the polar circle, measured a quarter of a mile, more or less, than one in France! With as much colour of reason they might have asserted, that in the midst of a storm, they could shoot an arrow, so skilfully as to split a hair at the distance of fifty yards! For even if they had had none of the difficulties to encounter which I have mentioned, an error of one-fourth of a minute in their celestial observations, would have rendered all their other operations useless; because such error would have comprehended as great a quantity as the assigned difference. And every man, who is experienced in the use of instruments for taking angles, will, if he be candid, acknowledge the impossibility

of measuring them to a certainty within much less than a minute→→→ particularly in the inconvenient situations I have described-even leaving out other weighty considerations, such as the imperfections of eye-sight, instruments, and the continual variations in the state of aërial refractions. The swagging oftheir measuring poles would cause a considerable error; and even the pole itself, if measured by a metallic foot, would be shorter in the northern than it would be in the southern latitudes. So that upon a just consideration of all the unconquerable obstacles that every where opposed these philosophers, through the whole process of their undertaking, I am of opinion, that Mr. La Lande, (in his History of Astronomy for 1805,) might have spared his expression of surprise, that his countrymen should have committed such a mistake at Tornea: the thing most surprising, in my opinion, is, that the measures of the different parties should so nearly coincide with each other, unless it be supposed, that theory required a tolerably near agreement !"

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The next chapter is devoted to a disquisition on the motion of the earth in an orbit, which our author considers to be imaginary and contradicted, by sight, reason, and Scripture! He says, the Newtonians

"Are so well satisfied of the utter insufficiency of all their elaborate arguments and boasted experiments to produce a direct and manifest proof, or any proof at all, to invalidate the divine assertion, that they are constrained to declare, that were it not for the fixed stars, it would be extremely difficult, if not impossible, to prove the motion of the earth. We should suppose that the planets made a complete revolution between any two similar situations with respect to the sun, because the places of elongation are similarly described, and are in quantity the same, whether the earth be in motion or not. It is from the apparent motion of the sun with respect to the fixed stars, that we conclude that the earth describes an orbit in about three hundred and sixty-five days.' Posterity will, I believe, read with astonishment, that the men of this age, by looking at the sun in motion, supposed it to stand still! And there is no appearance, even according to their own admission, and consequently no proof, of the earth's motion; why not draw the natural and obvious conclusion, that the sun really describes the orbit which he appears to do? That, however, would not suit their purpose, and therefore they go on to assert, that the strongest objection that can be made against the earth's motion round the sun, is that, in opposite points of the earth's orbit, its axis, which always keeps a parallel direction, would point to different fixed,stars, which is not found to be the fact. But this objection is easily removed by considering' (not by experiment,) the immense distance of the fixed stars, in respect of the diameter of the earth's orbit, the latter being no more than a point when compared with the former.' Thus they consider a thing as they would have it, and then they positively assert that it is so!"

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"Further, he says, we are required to believe, that in December, we are about 200,000,000 of miles from the place we left in June, though

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