FLATTENING OF THE EARTH.
At the Academy of Sciences at Paris, a memoir was read by Captain Duperrey, on the experiments made with the invariable pendulum, during the voyage of the Coquille round the world. He states that various experiments confirmed the fact of the flattening of the terrestrial globe, conjectured by several travellers, who had remarked that the number of oscillations which the pendulum made at certain places, differed from what had been observed in the extent of the same parallel. The principal anomalies observed by Captain Duperrey were at the Isle of France, Mons, Guam, and the Island of Ascension. At the Isle of France, the invariable pendulum (as had been remarked by M. Freycinet) made in one day, upon an average, thirteen or fourteen oscillations more than it ought, supposing the depression to be 1.305, according to the lunar theory. At Ascension, the acceleration, as noticed by Captain Sabine, was five or six oscillations, even supposing the depression to be 1.228. At other stations the difference was almost nothing; and in some, the motion of the pendulum was retarded. Such differences, Captain Duperry remarks, between the results of experiment and those given by theory, cannot be attributed to errors of observation. He is disposed to refer the cause of the phenomena, with Captain Sabine, to the want of homogeneousness in the earth, considered as a mass, or to the mere variations of density in the superficial strata. What tends to confirm this hypothesis, he says, is, that all observations show that an acceleration of the pendulum generally takes place on volcanic ground and a retardation on such as is sandy and argillaceous. A very important question to ascertain is, whether the flattening is exactly the same in both hemispheres. From the observations of Captains Duperrey and Freycinet, it appears that in the southern hemisphere it is 1.291, and in the northern 1.288; that is to say, it is sensibly the same, or 1.290 in both.