into its original foot of water. To suppose any void in creation, is blasphemy against the omnipresent Creator. 623. The property of infinite divisibility will be evident, from the consideration that every particle of matter, however small, must have an upper and an under side. The power of mutual attraction, or rather, of universal pressure, is proved by the falling of all loose bodies to the ground, in a perpendicular direction, towards the centre of the earth; by the motions of the planetary bodies round the sun; by the combined or curved direction of projected bodies; and by the continually accelerating motion of falling bodies. Obs. 1.-The infinite divisibility of matter is evident, in the formation of animalculæ, already treated of, and of the malleability of gold. Scents are equally subtile; and it is computed, that the millionth part of a grain of musk, divides itself into seven quadrillions of parts, in scenting a room. So, also, the light generated by a single grain of tallow, diffuses itself over a space two miles round. 2.-Accelerated motion, in falling bodies, is created by new impulses of attraction, or pressure, acting on a body already possessed of a given motion, and which acts at every instant, as though no motion were already acquired. The motion is, as the square of the times employed in falling. Thus,― Seconds of time, 1, 2, 3, 4, 5, &c. 9, 16, 80, 180, 320, 25, &c. 500, &c. Feet of motion, 20, 3.-Attraction, or pressure, is always in proportion to the quantity of matter in bodies; and it decreases by the same law as surfaces increase, i. e. according to the squares of the distances of the bodies from each other. 4.-Light and heat observe the same law; and decrease according to the square of the distance of the luminous body because, as light and heat diverge from a centre, their density on every surface presented to them, will necessarily be as the square of the distance, or radii of the diverging influences or rays. 5.-Kepler ascertained, and Sir Isaac Newton demonstrated, that from the combined forces of attraction and rectilinear motion, the squares of the periodical times or revolutions of the planets are, as the cubes of their distances. Hence, the distance of the earth from the sun being ascertained, and the times of all the planetary revolutions being known from observation, their several distances are ascertained by a simple rule of proportion. 6.-The following are the conclusions of Sir Richard Phillips, relative to the laws of the planetary motions : The rotatory motion of a planetary body subject to a uniform external pressure, from a uniformly diffused medium, is a necessary consequence of a peculiar and nicely adjusted disposition of the component parts in regard to their density. A rotatory and centrifugal motion, is a consequence of the lighter parts being fluid, and producing oscillations against the denser parts of corresponding and competent force, varying, at the same time, the centre of motion. A motion of that centre in a circular orbit, is a consequence of the combined force of the oscillations, with the diminished pressure of the NEAR or inner side of the body in regard to a larger or centrical body, as in the earth and sun. An elliptical orbit inclined to the plane of the equator of the moving body, is, then, a consequence of the arrangement of an excess of the oscillating fluid in one of the hemispheres, -as in our southern hemisphere. No peculiar numerical laws of pressure in the universal medium, nor any given centrifugal force, are required to effect the motions of the planetary bodies. It is sim ply necessary, that the powers should be uniform, universal, and in a degree calculated to balance each other under the existing circumstances. Such an accommodation of powers evidently exists, in a peculiar manner, in an oscillating fluid, as applied to counteract the uniform pressure of an universal medium. Its centrifugal impetus would mechanically be increased from a pound, avoirdupois, to millions of tons, as the inverse ratio of the squares of the distances might require. But no violence, or extraordinary force, belongs to the motions of nature. It is probable, that the pressure towards the sun in the earth, for example, is little more than is requisite, slightly to destroy its inertia. This pressure is easily counteracted, by the oscillations of the waters, (and as nature does nothing abruptly, may we not add, that of the atmosphere also,) so that the progression in the orbit between the poised forces is serene, quiet, and grand; not dissimilar, perhaps, to that of a balloon on a calm day. A centripetal impulse arising, therefore, from the pressure of the elastic fluid, or subtle medium, filling all space, inclines the planetary bodies mechanically towards each other, on their near sides, by a very slight and finely diminished force; which is counteracted by a centrifugal force, created by a rotative motion; which again is itself a consequence, of such an arrangement of the integral parts of the masses, with respect to density and fluidity, as constantly varies their centre of motion. The result of the combined forces, is a progressive motion of all the systems of bodies round their common centres of motion; such as we observe in the solar system; and such as doubtless exists in every system in the universe; whether of separate bodies-of planet and satellites of sun, comets, and planets-of suns amongst themselves-or of systems of suns in regard to each other. XXIX. Of Chronology and History. 624. Chronology is the art which enables us to measure and regulate time past, and time future : and History records, classes, and recounts events which have happened in past ages; and is, consequently, a register of the experience of mankind; and a source of practical wisdom, for kings, governors, and persons in authority. 625. Nature divides time into days, nights, and seasons. Savage nations added the division of moons, which are about 29 days. Civilized nations have agreed to reckon the period of the rotation of the earth round the sun, and call it a year; and they again subdivide this into its 12 moons, (moonths, or months.) But 12 equal moons make but 354 days, and the earth is 3654 days going round the sun; Julius Cæsar, therefore, varied the months as we now have them, so as to make 365 days. Obs.-The Hebrews and Greeks added an extra month every third or fourth year; but as the revolution of the earth was a quarter of a day longer than 365, Cæsár directed the 6th of March to be counted twice in every 4th year, so as to keep the reckoning of mankind equal with that of the heavenly bodies. This, however, was not correct; for the actual revolution of the earth is not quite a quarter of a day more than 365, but only 5 hours 48 minutes, and 57 seconds; consequently 11 minutes 3 seconds, are gained every year, or a whole day in 131 years. 626. In 1752, this gain of 11 minutes, 3 seconds, per annum, had carried the reckoning 11 days before its proper time; the style of reckoning, therefore, was altered, and 11 days dropt, by act of parliament; the day after the 1st of September being called the 12th. It was settled also, that in every 400 years, three leap-years in three centuries should be dropt; so that, in future, the annual recurring year will keep pace with time, within two or three seconds per annum. 627. The year is also divided into 52 weeks, and one day over; the weeks into seven days, or rotations of the earth on its own axis; those rotations into 24 hours; each hour into 60 minutes ; and each minute into 60 seconds, or periods, in which a pendulum that is 39,2. inches long, will vibrate. The vibration of such a pendulum, or a second, is therefore the first measure of time; but a pendulum of a fourth the length, will vibrate half seconds; seconds are also, in calculations, divided into 60 thirds, fourths, &c. 628. The names of the days of the week are derived from the names of certain Saxon objects of worship. As Sunday, or the first day, from the Sun. Tuesday, from Tuisco, a German hero; whence they call themselves Tuitschen, or Dutchmen. Wednesday, from Woden, their god of battle. Thursday, from Thor, the god of winds and weather, Friday, from Friga, the goddess of peace and plenty. And Saturday, the seventh day, from Seator, the god of freedom. Obs. The Romans called the days after the planets : |