PARIS. Academy of Sciences, September 12.— M. Léon Guignard in the chair.—R. Serville: The conical pendulum as affected by a screen.—L Dunoyer: The induction spectrum of rubidium. The metal was distilled in a vacuum into a quartz tube and the latter placed in the field of a high-frequency alternating current. The tube is luminous even at the ordinary temperature, and is a bright violet-blue at 100° C. At 200° C. the colour changes to lilac. With an exposure of twenty minutes as many as 332 lines were photographed; the arc spectrum of rubidium contains about 30 lines, and the spark spectrum about 60. A list of the wave-lengths is given, of which only two appear in the arc or flame spectra.—R. de Mallemann: The inversion of the rotatory power of derivatives of tartaric acid.—Q. Majorana: The absorption of gravitation.—M. Stuart-Mentiath: Granitised outcrops of the border of the Pyrenees.—E. F. Terroine and R. Wurmser: The influence of temperature on the utilisation of glucose in the development of Aspergillus niger.