would be mere trifles. But we are prepared to press this argument still farther and to insist upon it as a fact susceptible of positive demonstration that the interior portions of the earth, whether fluid or solid are not now in an intensely heated state. For the substance of the following argument I am indebted to an article writen by Dr. Nathaniel Bowditch, by whom it is ascribed to the celebrated French Mathematician La Place. The article referred to, may be found in the 21 vol. of the N. A. Review.
If the central portion of the earth is intensely heated, it must be constantly cooling, and thus approaching towards the medium temperature of the surrounding space. But if the temperature of the earth were to be diminished, by any given quantity, its dimensions, by a known chemical law must also be diminished. The various particles of matter would thus be brought near to the axis of rotation. But by a demonstrated and well known law of motion the sum of the arcs described by each particle would remain the same; and hence the angular velocity of the earth's rotation, would be increased, and the time of its revolution on its axis would be proportionally diminished. Such diminution, if it actually occurred to any extent, could be detected by comparing the earths revolutions with the orbitual movements of the moon and other planets. For example the absolute time of the moon's periodical revolution would note altered, but being measured by days, that had decreased in length, the period of the moon's revolutions would therefore appear to be longer, and would require an additional number of our minutes or seconds for their movements. But the time of the moon's periodical revolution around the earth, has been known with great accuracy for the last two thousand years, and during that time it has maintained the same relation to the diurnal revolutions of the earth;—at least there has been no perceptible change. Therefore no important change of temperature can have taken place in the earth during that period. M, Arago, the celebrate
