SOCIETIES AND ACADEMIES

Abstract

PARISAcademy of Sciences, September 30.—M. Fizeau in the chair.—The following papers were read:—Formation of an astronomical museum at the Observatory of Paris, by M. Mouchez. This is to include portraits of astronomers and savants, a collection of medals, drawings and photographs of celestial objects and phenomena, ancient instruments, &c.—Experimental facts showing that abundant sudoral secretions are not necessarily connected with excessive activity of cutaneous circulation, by M. Vulpian. In a dying cat, e.g., when the heart's action is much weakened, and the digital parts are bloodless, the sweat exudes freely from these parts.—Remarks on the phonograph and the telephone, by M. Bouillaud. —Determination of the exact number of irreducible co-variants of the binary cubo-biquadratic system, by Prof. Sylvester.—Industrial utilisation of solar heat, by M. Mouchot. This describes experiments made during the Exhibition. Inter alia, he set in action, on September 2, a solar receiver with mirror having an aperture of about twenty square metres. It had, at the focus, an iron boiler weighing, with accessories, 200 kilogrammes, and having a capacity of 100 litres (30 for the steam chamber and 70 for the liquid). In half-an-hour the 70 litres were raised to boiling, and the manometer soon registered 6 atm. pressure. On September 22, with slightly veiled sun, he got 6.2 atm., and worked, under a pressure of 3 atm., a Tangye pump raising 1,500 to 1,800 litres of water hourly to the height of 2 m. With a clear sky on the 29th ult. 7 atm. was reached.—Discovery of a small planet at the observatory of Ann-Arbor, by Mr. Watson.—On intra-mercurial planets, by M. Gaillot—On molecular attraction in its relations to the temperature of bodies, by M. Levy. To know all the isothermal and all the adiabatic lines of a body, and so to be able to study it completely, it is necessary and sufficient to know two of its isothermal lines and only one of its adiabatic lines.—On losses of charge produced in the outflow of a liquid when the section of the flow undergoes a sudden increase, by M. Boussinesq.—On the rotary power of quartz and its variation with the temperature, by M. Joubert. The angular coefficient of the curve of variation increases at first pretty rapidly up to 300°- From this to 840° (the boiling point of cadmium) it is nearly constant and the curve nearly a straight line with point of inflexion about 500°. Beyond 840° and up to 1,500°, the rotatory power increases only with extreme slowness. With a quartz of 46.172 mm., giving a rotation of 1,000° at zero, the increase from 300° to 900° is twelve minutes per degree. With a quartz of only 11 mm. the increase would still be three minutes per degree. Thus quartz makes an extremely sensitive thermometer, with the essential condition of comparability.—Phonic wheel for regularisation of the synchronism of motions, by M. Lacour. An iron-toothed wheel turns with its teeth very near an electro-magnet which is caused to exert periodic attraction by means of a vibrating diapason.—On the presence of isopropylic, normal butylic, and secondary amylic alcohols in the oils and alcohols of potatoes, by M. Rabuteau.