Academy of Sciences, Oct. 5.- M. Bertrand in the chair. __The following papers were read:-Researches on the conditions of resistance in cylindrical boilers, by?. H. Resal.-On the exact values of the angles in the crystals of titaniferous iron, by?. N. de Kokscharow˜-Report on the machine for freezing by the evaporation of methylic ether, invented by M. Ch. Tellier; and on the preservation of meat in the air, cooled by this apparatus, by the Commissioners, MM. Milne-Edwards, Peligot, and Bouley. -On the temperature of the sun, by M. J. Violle. The author starts with the fundamental equation aP - a* = - ax, and from s determinations of the intensity of solar radiation assigns the value 15500 to what he calls the effective temperature of the sun. The true mean temperature of the surface of the sun is estimated at 2,000°.-Note on magnetism, by M. J. M. Gangain, a continuation of former researches.-Seventh note on the conductivity of J igneous bodies, and of other substances which are bad conductors, by M. Th. du Moncel.-Experimental researches on explosive substances, by MM. Roux and Sarran.-On a register giving continuous indications for the determination of the law of variation of pressures produced by the gases of gunpowder, by M. Ricq.-On the synthesis of purpurine, and of some analogous colouring matters, by M. A. Rosenstiehl.-New observations on the chemical composition of the waters of Bagneres-de-Luchon, by?. E. Filhol.-Method of determination of copper by means of titrated liquids, by M. Pr. Lagrange.-Comparative and critical examination of the hypotheses which have been advanced to explain the figure of comets and the acceleration of their motion, by?. H. Champion. The author attempts to show in this memoir: (1) that a force directed along the radius vector develops in the two opposite parts of an elliptical orbit separated by the major axis, two tangential components of contrary signs, of which the effects are exactly compensating; (2), that the force gives rise to a third component opposed to gravitation, of which the final result is to increase the dimensions of the orbit · (t) it shown that at the distance at which comets' tails commence to be seen, the rays of the sun would not produce an appreciable elevation of temperature in a highly rarefied substance. -On the comparative chemical composition of the different parts of the vine when healthy and when attacked by Phylloxera by? Boutin.-Experiments made at Cognac on phylloxerised vines with the coal-tar recommended by M. Petit, by M. P. Mouille-fert.-Experiments made at Montpelier with the same substance by M. Alph. Rommier.-Observations on the points gained by science concerning the known species of the genus Phylloxera · a letter from M. Signoret to the perpetual secretary. - Observations concerning the recent communication of M. Balbiani on the different known species of the genus Phylloxera, by M. Lich-tenstein.-Trial of infection of a healthy vine by putting Phylloxera in contact with its roots, by M. Delorme.__ On the 6means proposed to check the propagation of Phylloxera, the method of uprooting in particular, by M. P. Naudin.-Experiments on a method of treatment of phylloxerised vines, by the sap of a Euphorb;a, by M. L. Balme.-On the appearance of Phylloxera in the canton of Geneva, and on different curative measures proposed, by M. E. Ador.-The Minister of Foreign Affairs transmitted further details of the recent eruption of Etna.-M. Dumas announced that the news received from the first four Transit of Venus expeditions was satisfactory on all points.-On the pretended Saharan Sea, by M. A. Pomel.-Observations on the ancient central sea of the Tuniso-Algerian Sahara, by M. Virlet d'Aoust.-On the theory of curves in space of? dimensions, by M. C. Jordan.-Electro-diapason of variable period, by?. E. Mer-cadier.-Electro·spectral tube, or "fulurator,“for the observation of the spectra of metallic solutions, by MM. B. Delachanal and A. Mermet.-Note on supersaturition, by M. Lecoq de Boisbaudran.-On the action of bromine on certain alcohols', by?. E. Hardy.-Note on the production ot oxamic acid by the oxidation of glycocol, by M. R. Engel.-Action of heat on diphenylmethane and phenyl-toluene; on the products of the reduction of benzophenoie, by M. Ph. Barbier.-Curious association of garnet, idiocrase and datholite, by M. J. Lawrence Smith.-Balloon meteorological observations, byM. G. Tissandier. -Note on the spectroscopic observations made during the balloon ascent of Sept. 24, for studying variations in the extension of the colours of the spectrum, by M. W. de Fonvielle.--On the feeble influence which diluvian waters have exercised on the formation of the valleys of the Paris basin, by?. E. Robert.