Chapter III: Part 3

If these suppositions are not admitted, may it not be presumed, that in the stroke of the comet against the sun, there was an elastic force which raised the torrent above the surface of the sun, instead of directly impelling it? which alone would be sufficient to remove the perihelion, and give the planets the motion they have retained. This supposition is not without probability, for the matter of the sun may possibly be very elastic, since light, the only part of it we are acquainted with, seems, by its effects, to be perfectly so. I own that I cannot say whether it is by the one or the other of these reasons, that the direction of the first motion of the impulse of the planets has changed, but they suffice to shew that such an alteration is not only possible but even probable, and that is sufficient for my purpose.

But, without dwelling any longer on the objections which might be made, I shall pursue the subject, and draw the fair conclusions on the proofs which analogies might furnish in favour of my hypothesis: let us, therefore, first see what might happen when these planets, and particularly the earth, received their impulsive motion, and in what state they were after having been separated from the sun. The comet having, by a single stroke, communicated a projectile motion to a quantity of matter equal to the 650th part of the sun's mass, the light particles would of course separate from the dense, and form, by their mutual attraction, globes of different densities: Saturn being composed of the most gross and light parts, would be the most remote from the sun: Jupiter being more dense than Saturn, would be less distant, and so on. The larger and least solid planets are the most remote, because they received an impulsive motion stronger than the smallest, and more dense: for, the force of impulsion communicating itself according to the surface, the same stroke would have moved the grosser and lighter parts of the matter of the sun with more velocity than the smallest and more weighty; a separation therefore will be made of the dense parts of different degrees, so that the density of the sun being equal to 100, that of Saturn will be equal to 67, that of Jupiter to 94-1/2, that of Mars to 200, that of the Earth to 400, that of Venus to 800, and that of Mercury to 2800. But the force of attraction not communicating like that of impulsion, according to the surface, but acting on the contrary on all parts of the mass, it will have checked the densest portions of matter; and it is for this reason that the densest planets are the nighest the sun, and turn round that planet with greater rapidity than the less dense planets, which are also the most remote.

Jupiter and Saturn, which are the largest and principal planets of the solar system, have retained the relation between their density and impulsive motions, in the most exact proportions; the density of Saturn is to that of Jupiter as 67 to 94-1/2 and their velocities are nearly as 88-2/3 to 120-1/72, or as 67 to 90-11/16; it is seldom that pure conjectures can draw such exact relations. It is true, that by following this relation between the velocity and density of planets, the density of the earth ought to be only as 206-7/18, and not 400, which is its real density; from hence it may be conceived, that our globe was formerly less dense than it is at present. With respect to the other planets, Mars, Venus, and Mercury, as their densities are known only by conjecture, we cannot be certain whether this circumstance will destroy or confirm our hypothesis. The opinion of Newton is, that density is so much the greater, as the heat to which the planet is exposed is the stronger; and it is on this idea that we have just said that Mars is one time less dense than the Earth, Venus one time, Mercury seven times, and the comet in 1680, 28,000 times denser than the earth: but this proportion between the density of the planets and the heat which they sustain, seems not well founded, when we consider Saturn and Jupiter, which are the principal objects; for, according to this relation between the density and heat, the density of Saturn would be about 4-7/18, and that of Jupiter as 14-17/22, instead of 67 and 94-1/2, a difference too great to be admitted, and must destroy the principles upon which it was founded. Thus, notwithstanding the confidence which the conjectures of Newton merit, I can but think that the density of the planets has more relation with their velocity than with the degree of heat to which they are exposed. This is only a final cause, and the other a physical relation, the preciseness of which is remarkable in Jupiter and Saturn: it is nevertheless true, that the density of the earth, instead of being 206-7/8, is found to be 400, and that consequently the terrestrial globe must be condensed in this ratio of 206-7/8 to 400.

But have not the condensations of the planets some relation with the quantity of the heat of the sun which they sustain? If so, Saturn, which is the most distant from that luminary, will have suffered little or no condensation; and Jupiter will be condensed from 90-11/16 to 94-1/2. Now the heat of the sun in Jupiter being to that of the sun upon the earth as 14-17/22 are to 400, the condensations ought to be in the same proportion. For instance, if Jupiter be condensed, as 90-11/16 to 94-1/2, and the earth had been placed in his orbit, it would have been condensed from 206-7/8 to 215-990/1451, but the earth being nearer the sun, and receiving a heat, whose relation to that which Jupiter receives is from 400 to 14-17/22, the quantity of condensation it would have experienced on the orbit of Jupiter by the proportion of 400 to 14-17/22, which gives nearly 234-1/3 for the quantity which the earth would be condensed. Its density was 206-7/8, by adding the quantity of its acquired condensation, we find 400-7/8 for its actual density, which nearly approaches the real density 400, determined to be so by the parallax of the moon. As to other planets, I do not here pretend to give exact proportions, but only approximations, to point out that their densities have a strong relation to their velocity in their respective orbits.

The comet, therefore, by its oblique fall upon the surface of the sun, having driven therefrom a quantity of matter equal to the 650th part of its whole mass; this matter, which must be considered in a liquid state, will at first have formed a torrent, the grosser and less dense parts of which will have been driven the farthest, and the smaller and more dense, having received only the like impulsion, will remain nearest its source; the force of the sun's attraction would inevitably act upon all the parts detached from him, and constrain them to circulate around his body, and at the same time the mutual attraction of the particles of matter would form themselves into globes at different distances from the sun, the nearest of which necessarily moving with greater rapidity in their orbits than those at a distance.

But another objection may be started, and it may be said, if the matter which composes the planets had been separated from the sun, they, like him, would have been burning and luminous bodies, not cold and opaque, for nothing resembles a globe of fire less than a globe of earth and water; and by comparison, the matter of the earth and planets is perfectly different from that of the sun?

To this it may be answered, that in the separation the matter changed its form, and the light or fire was extinguished by the stroke which caused this motion of impulsion. Besides, may it not be supposed that if the sun, or a burning star, moved with such velocity as the planet, that the fire would soon be extinguished; and that is the reason why all luminous stars are fixed, and that those stars which are called new, and which have probably changed places, are frequently extinguished and lost? This remark is somewhat confirmed by what has been observed in comets; they must burn to the centre when they pass to their perihelium: nevertheless they do not become luminous themselves, they only exhale burning vapours, of which they leave a considerable part behind them in their course.

I own, that in a medium where there is very little or no resistance, fire may subsist and suffer a very great motion without being extinguished: I also own, that what I have just said extends only to the stars which totally disappear, and not to those which have periodical returns, and appear and disappear alternately without changing place in the heavens. The phenomena of these stars has been explained in a very satisfactory manner by M. de Maupertuis, in his discourse on the figures of the planets. But the stars which appear and afterwards disappear entirely, must certainly have been extinguished, either by the velocity of their motion, or some other cause. We have not a single example of one luminous star revolving round another; and among the number of planets which compose our system, and which move round the sun with more or less rapidity, there is not one luminous of itself.

It may also be added, that fire cannot subsist so long in the small as in large masses, and that the planets must have burnt for some time after they were separated from the sun, but were at length extinguished for want of combustible matter, as probably would be the sun itself, and for the same reason; but in a length of time as far beyond that which extinguished the planets, as it exceeds in quantity of matter. Be this as it may, the matter of which the planets are formed being separated from the sun, by the stroke of a comet, that appears a sufficient reason for the extinction of their fires.

The earth and planets at the time of their quitting the sun, were in a state of total liquid fire; in this state they remained only as long as the violence of the heat which had produced it; and which heat necessarily underwent a gradual decay: it was in this state of fluidity that they took their circular forms, and that their regular motions raised the parts of their equators, and lowered their poles. This figure, which agrees so perfectly with the laws of hydrostatics, I am of opinion with Leibnitz, necessarily supposes that the earth and planets have been in a state of fluidity, caused by fire, and that the internal part of the earth must be a vitrifiable matter, of which sand, granite, &c. are the fragments and scoria.

It may, therefore, with some probability, be thought that the planets appertained to the sun, that they were separated by a single stroke, which gave to them a motion of impulsion, and that their position at different distances from the sun proceeds only from their different densities. It now only remains, to complete this theory, to explain the diurnal motion of the planets, and the formation or the satellites; but this, far from adding difficulties to my hypothesis, seems, on the contrary, to confirm it.

For the diurnal motion, or rotation, depends solely on the obliquity of the stroke, an oblique impulse therefore on the surface of a body will necessarily give it a rotative motion; this motion will be equal and always the same, if the body which receives it is homogeneous, and it will be unequal if the body is composed of heterogeneous parts, or of different densities; hence we may conclude that in all the planets the matter is homogeneous, since their diurnal motions are equal, and regularly performed in the same period of time. Another proof that the separation of the dense or less dense parts were originally from the sun.

But the obliquity of the stroke might be such, as to separate from the body of the principal planet a small part of matter, which would of course continue to move in the same direction; these parts would be united, according to their densities, at different distances from the planet, by the force of their mutual attraction, and at the same time follow its course round the sun, by revolving about the body of the planet, nearly in the plane of its orbit. It is plain, that those small parts so separated are the satellites: thus the formation, position, and direction of the motions of the satellites perfectly agree with our theory; for they have all the same motion in concentrical circles round their principal planet; their motion is in the same direction, and that nearly in the plane of their orbits. All these effects, which are common to them, and which depend on an impulsive force, can proceed only from one common cause, which is, impulsive motion, communicated to them by one and the same oblique stroke.

What we have just said on the cause of the motion and formation of the satellites, will acquire more probability, if we consider all the circumstances of the phenomena. The planets which turn the swiftest on their axis, are those which have satellites. The earth turns quicker than Mars in the relation of about 24 to 15; the earth has a satellite, but Mars has none. Jupiter, whose rapidity round its axis is five to six hundred times greater than that of the earth, has four satellites, and there is a great appearance that Saturn, which has five, and a ring, turns still more quickly than Jupiter.

It may even be conjectured with some foundation, that the ring of Saturn is parallel to the equator of the planet, so that the plane of the equator of the ring, and that of Saturn, are nearly the same; for by supposing, according to the preceding theory, that the obliquity of the stroke by which Saturn has been set in motion was very great, the velocity around the axis will, at first, have been in proportion as the centrifugal force exceeds that of gravity, and there will be detached from its equator and neighbouring parts, a considerable quantity of matter, which will necessarily have taken the figure of a ring, whose plane must be nearly the same as that of the equator of the planet; and this quantity of matter having been detached from the vicinity of the equator of Saturn, must have lowered the equator of that planet, which causes that, notwithstanding its rapidity, the diameters of Saturn cannot be so unequal as those of Jupiter, which differ from each other more than an eleventh part.

However great the probability of what I have advanced on the formation of the planets and their satellites may appear to me, yet, every man has his particular measurement, to estimate probabilities of this nature; and as this measurement depends on the strength of the understanding to combine more or less distant relations, I do not pretend to convince the incredulous. I have not only thought it my duty to offer these ideas, because they appear to me reasonable, and calculated to clear up a subject, on which, however important, nothing has hitherto been written, but because the impulsive motion in the planets enter at least as one half of the composition of the universe, which gravity alone cannot unfold. I shall only add the following questions to those who are inclined to deny the possibility of my system.

1. Is it not natural to imagine, that a body in motion has received that motion by the stroke of another body?

2. Is it not very probable, that when many bodies move in the same direction, that they have received this direction by one single stroke, or by many strokes directed in the same manner?

3. Is it not more probable that when many bodies have the same direction in their motion, and are placed in the same plane, that they received this direction and this position by one and the same stroke, rather than by a number?

4. At the time a body is put in motion by the force of impulsion, is it not probable that it receives it obliquely, and, consequently, is obliged to turn on its axis so much the quicker, as the obliquity of the stroke will have been greater? If these questions should not appear unreasonable, the theory, of which we have presented the outlines, will cease to appear an absurdity.

Let us now pass on to something which more nearly concerns us, and examine the figure of the earth, on which so many researches and such great observations have been made. The earth being, as it appears by the equality of its diurnal motion and the constancy of the inclination of its axis, composed of homogeneous parts, which attract each other in proportion to their quantity of matter, it would necessarily have taken the figure of a globe perfectly spherical, if the motion of impulsation had been given it in a perpendicular direction to the surface; but this stroke having been obliquely given, the earth turned on its axis at the moment it took its form; and from the combination of this impulsive force, the attraction of the parts, there has resulted a spheroid figure, more elevated under the great circle of rotation, and lower at the two extremities of the axis, and this because the action of the centrifugal force proceeding from the diurnal rotation must diminish the action of gravity. Thus, the earth being homogeneous, and having received a rotative motion, necessarily took a spheroidical figure, the two axes of which differ a 230th part from each other. This may be clearly demonstrated, and does not depend on any hypothesis whatever. The laws of gravity are perfectly known, and we cannot doubt that bodies attract each other in a direct ratio of their masses, and in an inverted ratio, at the squares of their distances; so likewise we cannot doubt, that the general action of any body is not composed of all the particular actions of its parts. Thus each part of matter mutually attracts in a direct ratio of its mass and an inverted ratio of its distance, and from all these attractions there results a sphere when there is no rotatory motion, and a spheroid when there is one. This spheroid is longer or shorter at the two extremities of the axis of rotation, in proportion to the velocity of its diurnal motion, and the earth has then, by virtue of its rotative velocity, and of the mutual attraction of all its parts, the figure of a spheroid, the two axes of which are as 229 to 230 to one another.

Thus, by its original constituent, by its homogeneousness, and independent of every hypothesis from the direction of gravity, the earth has taken this figure of a spheroid at its formation, and agreeable to mechanical laws: its equatorial diameter was raised about 6-1/2 leagues higher than under the poles.

I shall dwell on this article, because there are still geometricians who think that the figure of the earth depends upon theory, and this from a system of philosophy they have embraced, and from a supposed direction of gravity. The first thing we have to demonstrate is, the mutual attraction of every part of matter, and the second the homogeneousness of the terrestrial globe; if we clearly prove, that these two circumstances are really so, there will no longer be any hypothesis to be made on the direction of gravity: the earth will necessarily have the figure Newton decided in favour of, and every other figure given to it by virtue of vortexes or other hypotheses, will not be able to subsist.

It cannot be doubted, that it is the force of gravity which retains the planets in their orbits; the satellites of Saturn gravitate towards Saturn, those of Jupiter towards Jupiter, the Moon gravitates towards the Earth: and Saturn, Jupiter, Mars, the Earth, Venus, and Mercury, gravitate towards the Sun: so likewise Saturn and Jupiter gravitate towards their satellites, the Earth gravitates towards the Moon, and the Sun towards the whole of the planets. Gravitation is therefore general and mutual in all the planetary system, for action cannot be exercised without a re-action; all the planets, therefore, act mutually one on the other. This mutual attraction serves as a foundation to the laws of their motion, and is demonstrated to exist by its effects. When Saturn and Jupiter are in conjunction, they act one on the other, and this attraction produces an irregularity in their motion round the Sun. It is the same with the Earth and the Moon, they also mutually attract each other; but the irregularities of the motion of the Moon, proceeds from the attraction of the Sun, so that the Earth, the Sun, and the Moon, mutually act one on the other. Now this mutual attraction of the planets, when the distances are equal, is proportional to their quantity of matter, and the same force of gravity which causes heavy matter to fall on the surface of the Earth, and which extends to the Moon, is also proportional to the quantity of matter; therefore the total gravity of a planet is composed of the gravity of each of its parts; from whence all the parts of the matter, either in the Earth or in the planets, mutually attract each other and the Earth, by its rotation round its own axis, has necessarily taken the figure of a spheroid, the axes of which are as 229 to 230. The direction of the weight must be perpendicular to the Earth's surface; consequently no hypothesis, drawn from the direction of gravity, can be sustained, unless the general attraction of the parts of matter be denied; but the existence of this mutual attraction is demonstrated by observations, and the experiment of pendulums prove, that its extension is general; therefore we cannot support an hypothesis on the direction of gravity without going against experience and reason.

Let us now proceed to examine whether the matter of which the terrestrial globe is composed be homogeneous. I admit, that if it is supposed the globe is more dense in some parts than in others, the direction of gravity must be different from what we have just assigned, and that the figure of the Earth would also differ agreeable to those suppositions. But what reason have we to make these suppositions? Why, for example, should we suppose that the parts near the centre are denser than those which are more remote? Are not all the particles which compose the globe collected together by their mutual attraction? hence, each particle is a centre, and there is no reason to believe, that the parts which surround the centre are denser than those which are about any other point. Besides, if one considerable part of the globe was denser than another, the axis of rotation would be found near the dense parts, and an inequality would ensue in the diurnal revolution; we should remark an inequality in the apparent motion of the fixed stars; they would appear to move more quick or slow in the zenith, or horizon, according as we should be placed on the denser or lighter parts of the earth; and the axis of the globe no longer passing through the centre of gravity, would also very sensibly change its position: but nothing like this ever happens; on the contrary, the diurnal motion of the earth is equal and uniform. At all parts of the Earth's surface, the stars appear to move with the same velocity at all heights, and if there be any rotation in its axis, it is so trifling as to have escaped observation: it must therefore be concluded, that the globe is homogeneous, or nearly so in all its parts.

If the earth was a hollow and void globe, and the crust of which, for example, not more than two or three miles thick; it would produce these effects. 1. The mountains would be such considerable parts of the whole thickness of the crust, that great irregularities in the motions of the Earth would be occasioned by the attraction of the Moon and Sun: for when the highest parts of the globe, as the Cordeliers, should have the Moon at noon, the attraction would be much stronger on the whole globe than when she was in the meridian of the lowest parts. 2. The attraction of mountains would be much more considerable than it is in comparison with the attraction of the whole globe, and experiments made at the mountain of Chimboraco, in Peru, would in this case give more degrees than they have given seconds for the deviation of the plumb line. 3. The weight of bodies would be greater on the tops of high mountains than on the planes; so that we should feel ourselves considerably heavier, and should walk with more difficulty in high than in low places. These observations, with many others that might be added, must convince us, that the inner parts of the globe is not void, but filled with a dense matter.

On the other hand, if below the depth of two or three miles, the earth was filled with a matter much more dense than any known, it would necessarily occur, that every time we descended to moderate depths, we should weigh much more, and the motion of pendulums would be more accelerated than in fact they are when carried from an eminence into a plain: thus, we may presume that the internal part of the Earth is filled with a matter nearly similar to that which composes its surface. What may complete our determination in favour of this opinion is, that in the first formation of the globe, when it took its present spheroidical figure, the matter which composed it was in fusion, and, consequently, all its parts were homogeneous, and nearly equally dense. From that time the matter on the surface, although originally the same with the interior, has undergone a variety of changes by external causes, which has produced materials of such different densities; but it must be remarked, that the densest matters, as gold and metals, are also those the most seldom to be met with, and consequently the greatest part of the matter at the surface of the globe has not undergone any very great changes with relation to its density; the most common materials, as sand and clay, differ very little, insomuch, that we may conjecture, with great probability, that the internal part of the earth is composed of a vitrified matter, the density of which is nearly the same as that of sand, and that consequently the terrestrial globe in general may be regarded as homogeneous.

Notwithstanding this, it may be urged, that although the globe was composed of concentrical strata of different densities, the diurnal motion might be equally certain, and the uniform inclination of the axis as constant and undisturbed as it could be, on the supposition of its being composed of homogeneous matter. I acknowledge it, but I ask at the same time, if there is any reason to believe that strata of different densities do exist? If these conclusions be not rather a desire to adjust the works of Nature to our own ideas? And whether in physics we ought to admit suppositions which are not founded on observations or analogy?

It appears, therefore, that the earth, by virtue of the mutual attraction of its parts and its diurnal motion, assumed the figure of a spheroid; that it necessarily took that form from being in a state of fluidity; that, agreeable to the laws of gravity and of a centrifugal force, it could have no other figure: that in the moment of its formation as at present, there was a difference between the two diameters equal to a 230th part, and that, consequently, every hypothesis in which we find greater or less difference are fictions which merit no attention.

But it may be said, if this theory is true, and if 229 to 230 is the just relation of the axis, why did the mathematicians, sent to Lapland and Peru, agree to the relation of 174 to 175? From whence does this difference arise between theory and practice? And is it not more reasonable to give the preference to practice and measures, especially when we have been taken by the most able mathematicians of Europe[109:A], and with all necessary apparatus to establish the result.

To this I answer, that I have paid attention to the observations made at the equator and near the polar circle; that I have no doubt of their being exact, and that the earth may possibly be elevated an 175th part more at the equator than at the poles. But, at the same time, I maintain my theory, and I see clearly how the two conclusions may be reconciled. This difference is about four leagues in the two axes, so that the parts at the equator are raised two leagues more than they ought to be, according to my theory; this height answers exactly to the greatest inequalities on the surface of the globe, produced by the motion of the sea, and the action of the fluids. I will explain; it appears that when the earth was formed, it must necessarily have taken, by virtue of the mutual attraction of its parts, and the action of the centrifugal force, a spheroidical figure, the axes of which differ a 230th part: the original earth must have had this figure, which it took when it was fluid, or rather liquified by the fire; but after its formation the vapours which were extended and rarefied, as in the atmosphere and tail of a comet, became condensed, and fell on the surface in form of air and water: and when these waters became agitated by the flux and reflux, the matters were, by degrees, carried from the poles towards the equatorial parts; so that the poles were lowered about a league, and those of the equator raised in the same proportion; this was not suddenly done, but by degrees in succession of time; the earth being also exposed to the action of the winds, air, and sun; all these irregular causes concurred with the flux and reflux to furrow its surface, hollow it into valleys, and raise it into mountains; and producing other inequalities and irregularities, of which, nevertheless, the greatest thickness does not exceed one league at the equator; this inequality of two leagues, is, perhaps, the greatest which can be on the surface of the earth, for the highest mountains are scarce above one league in height, and there is much probability of the sea's not being more at its greatest depth. The theory is therefore true, and practice may be so likewise; the earth at first could not be raised above 6-1/2 leagues more at the equator than the poles, but the changes which have happened to its surface might afterwards raise it still more. Natural History wonderfully confirms this opinion, for we have proved in the preceding discourse that the flux and reflux, and other motions of the water, have produced mountains and all the inequalities on the surface of the globe, that this surface has undergone considerable changes, and that at the greatest depths, as well as on the greatest heights, bones, shells and other wrecks of animals, which inhabit the sea and earth, are met with.

It may be conjectured, from what has been said, that to find ancient earth, and matters which have never been removed from the spot in which they were first placed, we must dig near the poles, where the bed of the earth must be thinner than in the Southern climates.

On the whole, if we strictly examine the measures by which the figure of the earth is determined, we shall perceive this hypothesis enters into such determination; for it supposes the earth to have the figure of a regular curve, whereas from the constant changes the earth is continually undergoing from a variety and combination of causes, it is almost impossible that it should have retained any regular figure, and hence the poles might, originally, only be flattened a 230th part, as Newton says, and as my theory requires. Besides, although we had exactly the length of the degree at the polar circle and equator, have we not also the length of the degree as exactly in France? And the measure of M. Picard, has it not been verified? Add to this that the augmentation and diminution in the motion of the pendulum, do not agree with the result drawn from measurement, and that, on the contrary, they differ very little from the theory of Newton. This is surely more than is requisite to convince us that the poles are not flattened more than a 230th part, and that if there is any difference, it can proceed only from the inequalities, which the water and other external causes have produced on its surface; but these inequalities being more irregular than regular, we must not form any hypothesis thereon, nor suppose, that the meridians are ellipses, or any other regular curves. From whence we perceive, that if we should successively measure many degrees of the earth in all directions, we still should not be certain by that alone, of the exact situation of the poles, nor whether they were depressed more or less than the 230th part.

May it not also be conjectured, that if the inclination of the axis of the earth has changed, it can only be produced by the changes which have happened to the surface, since all the rest of the globe is homogeneous; that consequently this variation is too little sensible to be perceived by astronomers, and that if the earth is not encountered with a comet, or deranged, by any other external cause, its axis will remain perpetually inclined as it is at present, and as it has always been?

In order not to omit any conjecture which appears reasonable, may it not be said, that as the mountains and inequalities which are on the surface of the earth have been formed by the flux and reflux of the sea, the mountains and inequalities which we remark on the surface of the moon, have been produced by a similar cause? they certainly are much higher than those of the earth, but then her tides are also much stronger, occasioned by the earth's being considerably larger than the moon, and consequently producing her tides with a superior force; and this effect would be much greater if the moon had, like the earth, a rapid rotation; but as the moon presents always the same surface to the earth, the tides cannot operate but in proportion to the motion arising from her libration, by which it alternatively discovers to us a segment of its other hemisphere; this, however, must produce a kind of flux and reflux, quite different from that of our sea, and the effects of which will be much less considerable than if the moon had from its course a revolution round its axis, as quick as the rotation of the terrestrial globe.

I should furnish a volume as large as that of Burnet or Whiston's, if I were to enlarge on the ideas which arise in support of the above; by giving them a geometrical air, in imitation of the last author, I might add considerably to their weight; but, in my opinion, hypothesis, however probable, ought not to be treated with such pomposity; it being a dress which borders so much on quackery.

FOOTNOTES:

[78:A] Vide Newton, 2d edit. page 525.

[79:A] Vid. Newton, page 405.

[109:A] M. de Maupertuis' Figure of the Earth.

ARTICLE II.

FROM THE SYSTEM OF WHISTON[115:A].

This Author commences his treatise by a dissertation on the creation of the world; he says that the account of it given by Moses in the text of Genesis has not been rightly understood; that the translators have confined themselves too much to the letter and superficial views, without attending to nature, reason, and philosophy. The common notion of the world being made in six days, he says is absolutely false, and that the description given by Moses, is not an exact and philosophical narration of the creation and origin of the universe, but only an historical representation of the terrestrial globe. The earth, according to him, existed in the chaos; and, at the time mentioned by Moses, received the form, situation and consistency necessary to be inhabited by the human race. I shall not enter into a detail of his proofs, nor undertake their refutation. The exposition we have just made, is sufficient to demonstrate the difference of his opinion with public facts, its contrariety with scripture, and consequently the insufficiency of his proofs. On the whole, he treats this matter as a theological controvertist, rather than as an enlightened philosopher.

Leaving these erroneous principles, he flies to ingenious suppositions, which, although extraordinary, yet have a degree of probability to those who, like him, incline to the enthusiasm of system. He says, that the ancient chaos, the origin of our earth, was the atmosphere of a comet: that the annual motion of the earth began at the time it took its new form, but that its diurnal motion began only when the first man fell. That the ecliptic cut the tropic of cancer, opposite to the terrestrial paradise, which was situated on the north-west side of the frontiers of Assyria: that before the deluge, the year began at the autumnal equinox: that the orbits of the planets, and the earth were then perfect circles. That the deluge began the 18th of November, 2365 of the Julian period, or 2349 years before Christ. That the solar and lunar year were then the same, and that they exactly contained 360 days. That a comet descending in the plane of the ecliptic towards its perihelion, passed near the globe of the earth the same day as the deluge began: that there is a great heat in the internal part of the terrestrial globe, which constantly diffuses itself from the centre to the circumference; that the form of the earth is like that of an egg, the ancient emblem of the globe; that mountains are the lightest part of the earth, &c. He afterwards attributes all the alterations and changes which have happened to the earth, to the universal deluge; then blindly adopts the theory of Woodward, and indiscriminately makes use of all the observations of that author on the present state of the globe; but assumes originality when he speaks of its future state: according to him it will be consumed by fire, and its destruction will be preceded by terrible earthquakes, thunder, and frightful meteors; the Sun and Moon will have an hideous aspect, the heavens will appear to fall, and the flames will be general over all the earth; but when the fire shall have devoured all the impurities it contains; when it shall be vitrified and rendered transparent as crystal, the saints and the blessed spirits will return and take possession of it, and there remain till the day of judgment.

These hypotheses, at the first glance, appear to be rash and extravagant assertions; nevertheless the author has managed them with such address, and treated them with such strength, that they cease to appear absolutely chimerical. He supports his subjects with much science, and it is surprising that, from a mixture of ideas so very absurd, a system could be formed with an air of probability. It has not affected vulgar minds so much as it has dazzled the eyes of the learned, because they are more easily deceived by the glare of erudition, and the power of novel ideas. Mr. Whiston was a celebrated astronomer, in the constant habit of considering the heavens, observing the stars, and contemplating the wonderful course of nature; he could never persuade himself that this small grain of sand, this Earth which we inhabit, occupied more the attention of the Creator than the universe, the vast extent of which contains millions of other Suns and Earths. He pretends, that Moses has not given us the history of the first creation of this globe, but only a detail of the new form that it took when the Almighty turned it from the mass of a comet into a planet, and formed it into a proper habitation for men. Comets are, in fact, subjected to terrible vicissitudes by reason of the eccentricity of their orbits. Sometimes, like that in 1680, it is a thousand times hotter there than red-hot iron; and sometimes a thousand times colder than ice; if they are, therefore, inhabited it must be by strange creatures, of which we can have no conception.

The planets, on the contrary, are places of rest, where the distance of the sun not varying much, the temperature remains nearly the same, and permits different kinds of plants and animals to grow and multiply.

In the beginning God created the world; but, observes our author, the earth was then an uninhabitable comet, suffering alternatively the excess of heat and cold, its liquifying and freezing by turns formed a chaos, or an abyss, surrounded with thick darkness: "and darkness covered the face of the deep," _& tenebræ erant superfaciam abissi_. This chaos was the atmosphere of the comet, a body composed of heterogeneous matters, the centre occupied by spherical, solid, and hot substances, of about two thousand leagues in diameter, round which a very great surface of a thick fluid extended, mixed with an unshapen and confused matter, like the chaos of the ancient _rudis & indigestaque moles_.

This vast atmosphere contained but very few dry, solid, or terrestrial particles, still less aqueous or aerial, but a great quantity of fluid, dense and heavy matters, mixed, agitated and jumbled together in the greatest disorder and confusion. Such was the earth before the six days, but on the first day of the creation, when the eccentrical orbit of the comet had been changed, every thing took its place, and bodies arranged themselves according to the law of gravity, the heavy fluid descended to the lowest places, and left the upper regions to the terrestrial, aqueous and aerial parts; those likewise descended according to their order of gravity; first the earth, then the water, and last of all the air. The immense volume of chaos was thus reduced to a globe of a moderate size, in the centre of which is the solid body that still retains the heat which the sun formerly communicated to it, when it belonged to a comet. This heat may possibly endure six thousand years, since the comet of 1680 required fifty thousand years to cool. Around this solid and burning matter, which occupies the centre of the earth, the dense and heavy fluid which descended the first is to be found, and this is the fluid which forms the great abyss on which the earth is borne, like cork on quicksilver; but as the terrestrial parts were originally mixed with a large quantity of water, in descending they have dragged with them a part of this water, which, not being able to re-ascend after the earth was consolidated, formed a concentrical bed with the heavy fluid which surrounds this hot substance, insomuch that the great abyss is composed of two concentrical orbs, the most internal of which is a heavy fluid, and the other water; the last of which serves for a foundation to the earth. It is from this admirable arrangement, produced by the atmosphere of a comet, that the Theory of the Earth, and the explanation of all its phenomena are to depend.

When the atmosphere of the comet was once disembarrassed from all the solid and terrestrial matters, there remained only the lighter air, through which the rays of the sun freely passed and instantly produced light: "Let there be light, and there was light." The columns which composed the orb of the Earth being formed with such great precipitation is the cause of their different densities: consequently the heaviest sunk deeper into this subterraneous fluid than the lightest; and it is this which has produced the vallies and mountains on the surface of the earth. These inequalities were, before the deluge, dispersed and situated otherwise than they are at present. Instead of the vast valley, which contains the ocean, there were many small divided cavities on the surface of the globe, each of which contained a part of this water; the mountains were also more divided, and did not form chains as at present: nevertheless, the earth contained a thousand times more people, and was a thousand times more fertile; and the life of man and other animals were ten times longer, all which was affected by the internal heat of the earth that proceeded from the centre, and gave birth to a great number of plants and animals, bestowing on them a degree of vigour necessary for them to subsist a long time, and multiply in great abundance. But this heat, by increasing the strength of bodies, unfortunately extended to the heads of men and animals; it augmented their passions; it deprived man of his innocence, and the brute creation of part of their intelligence; all creatures, excepting fish, who inhabited a colder element, felt the effects of this heat, became criminal and merited death. It therefore came, and this universal death happened on Wednesday the 28th of November, by a terrible deluge of forty days and forty nights, and was caused by the tail of another comet which encountered the earth in returning from its perihelion.

The tail of a comet is the lightest part of its atmosphere; it is a transparent mist, a subtile vapour, which the heat of the sun exhales from the body of the comet: this vapour composed of extremely rarefied aqueous and aerial particles, follows the comet when it descends to its perihelion, and precedes when it re-ascends, so that it is always situate opposite to the sun, as if it sought to be in the shade, and avoid the too great heat of that luminary. The column which this vapour forms is often of an immense length, and the more a comet approaches the sun, the longer and more extended is its tail, and as many comets descend below the annual orb of the earth, it is not surprising that the earth is sometimes found surrounded with the vapour of this tail; this is precisely what happened at the time of the deluge. In two hours the tail of a comet will evacuate a quantity of water equal to what is contained in the whole ocean. In short, this tail was what Moses calls the cataracts of Heaven, "and the cataracts of Heaven were opened." The terrestrial globe meeting with the tail of a comet, must, in going its course through this vapour, appropriate to itself a part of the matter which it contains; all which, coming within the sphere of the earth's attraction, must fall on it, and fall in the form of rain, since this tail is partly composed of aqueous vapours. Thus rain may come down in such abundance as to produce an universal deluge the waters of which might easily surmount the tops of the highest mountains. Nevertheless, our author, cautious of not going directly against the letter of holy writ, does not say that this rain was the sole cause of the universal deluge, but takes the water from every place he can find it. The great abyss as we see contains a considerable quantity. The earth, at the approach of the comet, would prove the force of its attraction; and the waters contained in the great abyss would be agitated by so violent a kind of flux and reflux, that the superficial crust would not resist, but split in several places, and the internal waters be dispersed over the surface, "And the fountains of the abyss were opened."

But what became of these waters, which the tail of the comet and great abyss furnished so liberally? our author is not the least embarrassed thereon. As soon as the earth, continuing its course, removed from the comet, the effects of its attraction, the flux and reflux in the great abyss ceased of course, and immediately the upper waters precipitated back with violence by the same roads as they had been forced upon the surface. The great abyss absorbed all the superfluous waters, and was of a sufficient capacity not only to receive its own waters, but also all those which the tail of the comet had left, because during its agitation, and the rupture of its crust, it had enlarged the space by driving out on all sides the earth that surrounded it. It was at this time also the figure of the earth, which till then was spherical, became elliptic. This effect was occasioned by the centrifugal force caused by its diurnal motion, and by the attraction of the comet, for the earth, in passing through the tail of the comet, found itself so placed that it presented the parts of the equator to that planet; and the power of the attraction of the comet, concurring with the centrifugal force of the earth, caused the parts of the equator to be elevated, and that with the more facility as the crust was broken and divided in an infinity of places, and because the flux and reflux of the abyss drove against the equator more violently than elsewhere.

Here then is Mr. Whiston's history of the creation; the causes of the universal deluge; the length of the life of the first men; and the figure of the Earth; all which seem to have cost our author little or no labour; but Noah's ark appears to have greatly disquieted him. In the midst of so terrible a disorder occasioned by the conjunction of the tail of a comet with the waters of the great abyss, in the terrible moments wherein not only the elements of the earth were confused, but when new elements still concurred to augment the chaos, how can it be imagined that the ark floated quietly with its numerous cargo on the top of the waves? Here our author makes great efforts to arrive at and give a physical reason for the preservation of the ark, but which has always appeared to me insufficient, poorly imagined, and but little orthodoxical: I will not here relate it, but only observe how hard it is for a man who has explained objects so great and wonderful, without having recourse to a supernatural power, to be stopt by one particular circumstance; our author, however, chose rather to risk drowning with the ark, than to attribute to the immediate bounty of the Almighty the preservation of this precious vessel.

I shall only make one remark on this system, of which I have made a faithful abridgement: which is, whenever we are rash enough to attempt to explain theological truths by physical reasons, or interpret purely by human views, the divine text of holy writ, or that we endeavour to reason on the will of the Most High, and on the execution of his decrees, we consequently shall involve ourselves in the darkness and chaos of obscurity and confusion, like the author of this system, which, in defiance of its absurdities, has been received with great applause. He neither doubts the truth of the deluge, nor the authenticity of the sacred writ; but as he was less employed with it than with physic and astronomy, he has taken passages of the scripture for physical facts, and the results of astronomical observations; and has so strangely blended the divine knowledge with human science as to give birth to the most extraordinary system that possibly ever was or will be conceived.

FOOTNOTES:

[115:A] A New Theory of the Earth by William Whiston, 1708.

ARTICLE III.

FROM THE SYSTEM OF BURNET.[128:A]

This author is the first who has treated this subject generally and in a systematical matter. He was possessed of much understanding, and was a person well acquainted with the _belles lettres_. His work acquired great reputation, and was criticised by many of the learned, among the rest by Mr. Keil, who has geometrically demonstrated the errors of Mr. Burnet, in a treatise called "Examination of the Theory of the Earth." Mr. Keil also refuted Whiston's system; but he treats the last author very different from the first, and seems even to be of his opinion in several cases, and looks upon the tail of a comet to be a very probable cause for the deluge. But, to return to Burnet, his book is elegantly written; he knew how to paint noble images and magnificent scenes. His plan is great, but the execution is deficient for want of proper materials: his reasoning is good, but his proofs are weak; yet his confidence in his writings is so great, that he frequently causes his readers to pass over his errors.