Societies and Academies

    Abstract

    PARIS Academy of Sciences, August 22.—M. Jamin in the chair.—The following papers were read:—Meridian observations of small planets and of Comet b 1881, at Paris Observatory, during the second quarter of 1881, by M. Mouchez.—Remarks on M. Jamin's note on comets, by M. Faye.—On spectrum analysis applied to comets, by the same.—On the nature of the repulsive force exercised by the sun, by the same. He associated it long ago with the state of incandescence of the sun; and, in an experiment, rare gaseous matter made luminous by means of an induction-spark was repelled by an incandescent plate at a sensible distance. Some thought this not decisive, however; for the gaseous matter might become more conductive through heating, so that the effect observed might be a sort of obscure discharge. M. Faye invites physicists to take up the matter afresh.—On the interior state of the terrestrial globe, by M. Roche. Supposing the globe formed of a nucleus or solid block nearly homogeneous, covered with a lighter layer, of density geologically shown to be about 3 in relation to water; he finds it possible to harmonise the general values of precession and flattening, if it be considered that the interior nucleus has solidified and taken its definitive form under influence of a rotation less rapid than that now animating the earth. The central block is probably like meteoric iron in specific gravity, while the enveloping layer is comparable to aëroliths of stony nature, with little iron.—On the irreducible co-variants of the binary quartic of the eighth order, by Prof. Sylvester.—On a new species of Cissus (Cissus Rocheana, Planch), from the interior of Sierra Leone, capable of bearing the winter of Marseilles, by M. Planchon. Its endurance is a matter of temperament, and a proof of the extent of the scale of resistance to cold and heat which some plants possess, and which often upsets all prevision. The American Vitis riparia lives sixty miles north of Quebec, and is also found in the sub-tropical Southern States.—On the laws of formation of cometary tails, by M. Schwedoff. Starting with the existence of an infinite number of ponderable particles in celestial space, he shows that those with parabolic orbits have most chance of collision and consequent heating and dispersion. The sudden vaporisation of solids, due to passage among them of a cometary nucleus, generates the cometary nebulosity. The velocity of propagation of visible waves accompanying the nucleus is equal to the velocity of the nucleus itself at the moment of departure of these waves. The maximum of intensity of a cosmic wave is found in the tangent to the orbit of the nucleus at the point of departure of the wave. With these two laws he seeks to explain the phenomena observed.—On a particular case of the theory of motion of an invariable solid in a resistant medium, by M. Willotte.—M. Trève communicated the results of some experiments as to the effects produced by shunts in telephonic circuits.—Solar observations at the Royal Observatory of the Roman College during the first quarter of 1881, by P. Tacchini. After the secondary minimum in the end of last year, the solar activity resumed its course towards the maximum. The distribution of protuberances, &c., was the same as in the last quarter of 1880.—Observations of solar spots and faculss in April to July, 1881, by P. Tacchini. A minimum of spots occurred in May, and an exceptional maximum in July; now, the activity is anew at a minimum. During this year several periods of abundant frequency have recurred.—Spectroscopic studies on comets b and c 1881, by M. Thollon. Comet c seems to be almost wholly gaseous. The brightness of the head and tail of the comets seems to vary rapidly and uniformly with distance from the sun; arguing that their white light is almost wholly reflected sunlight. The slowness of variation of the band spectrum is against the view that the cometary elements are rendered incandescent by calorific action of the sun. The comets have probably a light and heat of their own.—Researches on the telluric lines of the solar spectrum, by M. Egoroff. Sending a strong electric beam through 18m. of aqueous vapour, and increasing the tension to 6 atm., the spectrum was notably changed in aspect. The group a in the extreme red he thinks fundamental for aqueous vapour, and he is going to examine it in detail.—On the existence of a new metallic element, actinium, in the zinc of commerce, by Mr. Phipson.—Note relative to a new series of phosphates and arseniates, by MM. Filhol and Senderens.— Fixation of hypochloous acids on propargylic compounds, by M. Henry.—On the abnormal presence of uric acid in the salivary, gastric, nasal, pharyngeal, sudoral, and uterine secretions, and in menstrual bloo; diagnostic and therapeutic indications, by M. Boucheron.—Observations during a thunderstorm on June 25, 1881, by M. Larroque.

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    Societies and Academies . Nature 24, 428 (1881). https://doi.org/10.1038/024428a0

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