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 365 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. Cæsar 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: as Solis, Sun; Lunæ, Moon; Martis, Mars; Mercurii, Mercury; Jovis, Jupiter; Veneris, Venus; and Saturni, Saturn. 629. The names of the 12 moons, or months, are derived from the Latin, as under: January, from Janus, the god of new-born infants. March, from Mars, the god of war, the first month of the Roman year. April, from Aperio, signifying to open the year, or the blossoms. May, from Maia, the mother of Mercury. June, from Juno, the wife of Jupiter. July, from Julius Cæsar, the Roman emperor. August, from Augustus Cæsar, the Roman emperor. September, from Septem, the seventh month of the Roman year, which began in March. October, from Octo, the eighth month of the Roman year. November, from Novem, the ninth month of the Roman year. December, from Decem, the tenth month of the Roman year. 630. It will be readily supposed, that owing to the various lengths of years, and the different modes of calculation practised by different nations, great differences of opinion have existed in regard to the date of past events. The great difficulty was, to fix the period of certain great event, as a sort of land-marks, from which to ascertain and correct others: these are The Creation * Before Christ. Years. 4004 2348 According to Cæsar, the mother of Mars was Juno, and Februa was a feast of atonement, held in the month of February, which, thence, received its name. |