Societies and Academies

Abstract

PARIS.Academy of Sciences, September 9.—M. Marey in the chair.—A memoir was presented by M. Wladimir de Nicolaiew, entitled “On the attempt to show currents of electric displacement and on the magnetic induction of iron in the alternative state.”—Results of solar observations, made at the Royal Observatory of the Roman College, during the first quarter of 1895, by M. P. Tacchini. The diminution of frequency of spots was maintained during this quarter with a secondary minimum in January. Protuberances showed the same minimum although the season was unfavourable for their observation.—On the forces developed by differences of temperature between the two main plates of a beam with continuous trusses, by M. H. Deslandres. From the experiments made, differences of temperature between the upper and lower plates of a continuous girder cause supplementary forces of compression and extension, frequently reaching in the hot season 2 kg. per millimetre.—Observations on M. Deslandres' note, by M. Maurice Lévy. An exact demonstration giving the means of deducing the strains in every case.—On a theorem in geometry, by M. Mendeléef.—On nitro-substitutions, by MM. C. Matignon and Deligny. The conclusions are given: (1) Isomerides of position have always been found to have the same heats of combustion within the errors of experiment; one only need be examined from a number of isomerides. (2) The mean difference in heats of combustion of a compound and its nitro-derivative is 45 Cal. Hence is deduced the equation