PARIS Academy of Sciences, September 28.—M. Bouley, President, in the chair.—Equilibrium of the moon, by M. F. Tisserand. In this paper calculations are submitted in support of M. Ch. Simon's theory, supplemented by M. Poisson, that, neglecting the excentricity of the lunar orbit, the axis of rotation is displaced in the interior of the moon in such a way as constantly to oscillate in the plane perpendicular to the main axis directed towards the earth.—Note on earthquakes, by M. A. d'Abbadie. The author gives an account of the seismic movements observed by him last winter in Egypt, where the seismograph was exceptionally active. He urges a systematic study of these phenomena in France, such as has already been commenced by M. E. de Rossi in Italy, and by Mr. Milne in Japan.—Researches on the nitric cellulose substances (gun cotton, &c.), by M. Ch. Er. Guignet. The constituents and properties are described of the four distinct nitric cellulose bodies hitherto determined, all of which may be regarded as derivatives of the cellulose C48H49O40, where 4eq., 6eq., 8eq., or 10eq. of water are replaced by the same number of equivalents of hydrated nitric acid.—Memoir on the treatment of phylloxera by means of the organic sulphurs and the polysulphides of ammonium obtained by dissolving powdered sulphur in the night-soil of cesspools, by M. J. Jullien. This treatment is described as inexpensive, thoroughly efficient, and applicable to every description of soil.—Note on an unpublished document by Sergio Venturi, dated February 26, 1610, on the invention and the theory of the telescope, recently edited by M. G. Govi. This letter, addressed by the writer to the Marquis John Baptist Manso at Naples, is specially interesting as being anterior to the earliest publications of Galileo on the telescope which had just been invented by Lippersheim in Holland Note on the separation of liquefied atmospheric air into two distinct fluids, by M. S. Wroblewski.—Description of two new types of condensing hygrometers, by M. Georges Sire. The essential character of these hygrometers is that the moisture is precipitated on a bright metallic surface without solution of continuity. Perfect equality of temperature is secured in both instruments by the agitation of the volatile fluid and the thinness of the walls of the cylindric tube.—Genesis of the crystals of sulphur in square tables (five illustrations), by M. Ch. Brame. The author's experiments on the genesis of the square tables of sulphur show the direct passage from the curve to the straight line in the development of these crystals.—Morphology of the mandibule of the hymenoptera, by M. Joannès Chatin. This organ of the hymenopteræ is shown to be perfectly analogous in all its parts to that of the grinding insects.—Note on the application of thermo-chemistry to the explanation of geological phenomena, continued; iron ores, by M. Dieulafait.