Abstract
PARIS. Academy of Sciences, October 20.—M. Duchartre in the chair.—Study of the movement of a double cone which appears to rise, though it really descends, on an inclined plane, by M. H. Resal. A double cone placed on two guides inclined to the horizon, and nearer to one another at the lower than at the upper end, appears to ascend. The author has studied the mechanics of this movement.—Note on lightning-flashes which meet one another, by M. A. Trécul. On September 29, M. Trouvelot presented a paper on the identity in the structure of lightning and discharges from an induction machine. The author calls attention to the fact that he made similar observations ten years ago.—Observations of Brookes's comet (March 19, 1890), made with the great equatorial of Bordeaux Observatory, by MM. G. Rayet, L. Picart, and Courty. Seventy-one observations for position are given, extending from June 21 to October 12.—Remarks relative to a cause of variation of latitudes, by M. R. Radau. The movements of the sea, as well as certain meteorological phenomena (avalanches, &c.), may give rise to small deviations of the axis of our globe. It is shown that a mass of water 2000 cubic kilometres in size could produce an effect large enough to be observed.—On the established variations in the observations of the latitude of the same place, by M. A. Gaillot. Observations made at Berlin, Potsdam, and Prague, indicate that the latitude of a place is subject to a periodic variation, the maximum occurring in the summer, and the minimum in the winter, the amplitude of the oscillation about the mean value being ± 0″˙25. M. Gaillot gives two hypotheses to account for this variation, and points out the means of testing each of them.They are: (1) the axis of rotation is changed in the interior of the earth, the poles describing a circumference about the mean position, of which the radius is 0″˙25 (7 or 8 metres); (2) the accepted periodic variation in observations of latitude is due to refraction phenomena.—Organization of spectroscopic researches with the great telescope of Paris Observatory, by M. Deslandres. (See Our Astronomical Column.)—Two solar prominences observed at the Haynald Observatory, Kalocsa (Hungary), by M. Jules Fényi. On August 15, at 9h. 39m., Paris mean time, a prominence reaching a height of 323″, was observed on the western edge of the sun. Its base extended from + 37°4′to + 44° 58′ heliographic latitude. Another prominence was seen on August 18, at 11h. 45m., between – 41° 29′ and – 55°. This attained a height of 418″, but was of a much more broken character than the preceding one.—On certain kinds of surfaces, by M. Lelieuvre.—Researches on the atomic weight of fluorine, by M. Henri Moissan. (See Notes, p. 649.)—Action of aromatic amines and of phenylhydrazine upon the β-ketonic nitriles, by M. L. Bouveault. The author establishes the generality of the reaction—
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Societies and Academies. Nature 42, 655–656 (1890). https://doi.org/10.1038/042655b0
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DOI: https://doi.org/10.1038/042655b0