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PARIS Academy of Sciences, October 23.—Vice-Admiral Paris in the chair.—The following papers were read:—Theorems relating to systems of three segments forming a constant length, by M. Chasles.—Remarks on a critique of Dr. Boué on the theory of trombes, by M. Faye. The gyration of the base of a trombe is generally too rapid to be perceived; but on reaching the ground or the sea, a quantity of dust or of water-droplets is raised by the escaping air, and passes obliquely before the trombe, with a perceptible slow movement. The spectator may by mistake attribute this motion to the trombe itself, and conclude that the trombe pumps the water (e.g.) up to the clouds. The trombe's motion is really a descending gyratory one. —On the order of appearance of the first vessels in the aerial organs of Ananallis arvensis, by M. Trécul.—Report to the Academy on the works of M. Francis Gamier, naval .lieutenant. M. Gamier died about three years ago. His travels in China have had important results. The Minister of Public Instruction, on the recommendation of the Academy, has appointed an annual pension of 1,200 francs to be given to his widow.—Note on electric effluves, by M. Boillot. To obtain the dark effluves the conducting tubes for the electricity should be sufficiently apart to prevent any phosphorescent glow in the darkness. M. Boillot describes some modifications of his apparatus.—On determination of the depth of the sea by means of the bathometer, and without use of a sounding line, by Dr. C. W. Siemens.—On the industrial applicatioas of phosphuret of copper and phosphorised bronze, by MM. de Ruolz, Montchal, and De Fontenay. Of two bells presented to the Academy, one made with phosphuret of copper in proportion of 0\100 gave sounds much superior in acuteness, intensity, and timbre, to those of the other bell, which was of an ordinary bronze (78 copper, 22 tin). Its composition was also more homogeneous. By reducing the proportion of phosphorus to a few thousandths, red copper may be cast in sand without its physical properties being sensibly altered as regards industrial use. A bronze alloy with the proportion of 3/1000 phosphorus, sustains friction well, and can be indefinitely recast without appreciable loss industrially.—On,the cure of hypertrophic elongation of the neck of the uterus by igneous utero-vaginal myotomy, by M. Abeille.—On the industrial preparation of nitre-glycerine, by MM. Boutmy and Faucher. (This note was in a sealed packet, deposited in August, 1872.) In the ordinary manufacture the reaction liberates much heat, which tends to decompose the nitro-glycerine formed. The authors first make sulpho-glyceric acid treating glycerine at 30° with three times its weight of sulphuric acid at 66°; and sulpho-nitric acid by mixing equal weights of sulphuric acid at 66° and nitric acid at 48°. Then these two acids are united, giving a mixture like this: glycerine, 100; nitric acid, 280; sulphuric acid, 600. The rise of temperature is then limited to 10° or 15°. .The reaction is finished in about twenty-four hours. The nitroglycerine forms in a distinct layer above the acids, from which it can be separated by decantation.—Report on experiments made, in several communes of Charente, with a view to destruction of phylloxera, by M. Boutin. To succeed well with sulpho-carbonate of potassium, alone or with water, or with coal-tarred sulphur carbonate, the operations should be done in October, November, or even December (if not too cold), then again from. March till the end of May.—On a general proposi* tion of the theory of conies, by M. Halphen.—On the effects of eddies observed in water-courses, by M. Bouquet de la Grye. If there be poured into a glass vessel first a dense liquid like aniline, then water, then oil, and the upper liquids be put in rotation with paddles, a central depression forms at the surface of the oil; a cone of the liquid descends in the centre, while a protuberance of niline rises from the bottom. A similar action of the eddies in rivers accounts for the raising and removal of sand, and the form assumed by the river's bed. And the movement of liquid threads in a river-bend may be compared to that in the vessel, taking as centre the successive points of the convex bank, and as border the concave part. There are vortices with horizontal axes also. The author thinks that by suitable dams, &c., the vis viva of the water might be utilised for deepening the channel.—On the laws of vibratory motion of tuning-forks, by M. Mercadier. The duration of the period of vibratory motion, increases or diminishes with the amplitude. This variation, even for considerable amplitudes of 1 cm., is very small, and extends only to the fourth figure. If a certain limit, which may be fixed at 4mm., be not exceeded, the duration of the period may be regarded as constant.—On the electrical apparatus of the torpedo, by M. Rouget. A histological description.
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Societies and Academies . Nature 15, 20 (1876). https://doi.org/10.1038/015020b0
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DOI: https://doi.org/10.1038/015020b0