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Academy of Sciences, Aug. 31.—M. Faye in the chair.— The following papers were read:—Astronomy at the Italian Spectroscopic Society, by M. Faye. This was a reply to some criticisms of P. Secchi. The author pointed out that P. Secchi's theory of sunspots was a return to the idea announced by Galileo in 1612, the clouds being buried in the body of the sun instead of floating above it. The theory advanced by the author on the other hand had been pronounced by Mr. Langley to be a vera causa. This vera causa, according to M. Faye, is nothing more than a law of hydrodynamics, perfectly established;for terrestrial air and water currents.-Remarks on the fish of the Algerian Sahara, by M. P. Gervais. The remarks refer to species of Coptodon and Cyprinodon, the former of which had been cited by M. Cosson as proving the continuity of the sheet of water which extended over this region.-Note on the development of the contractile coat of the vessels, an anatomical paper by M. C. Rouget. New researches undertaken by the author on amphibian larvse establish beyond doubt the contractibility of the ramified protoplasmic cells observed last year in the vessels of the hyaloid membrane of the adult frog.-On winged Phylloxera and its progeniture, by M. Balbiani. The author points out the complete analogy between Phylloxera vastatrix and the Phylloxera of the oak.-New observations on the migrations of Phylloxera to the surface of the soil and on the effects of the method of submersion, a letter from M. G. Bazille to M. Dumas. The letter contained a note, published in the Messager du Midi. -M. P. Mouillefert addressed also a letter containing observations on the employment of the chief insecticides from experiments tried in the laboratory at Cognac and on the vines of the neighbourhood.-M. P. Rohart addressed a letter on the action exercised by the soil on insecticide gases.-Other communications relating to Phylloxera were received from MM. Delfan, A. Richard, Gauthier, L. Rousseau, & c.-On a physiological phenomenon produced by excess of imagination, a letter from M. P. Volpicelli to M. Chevreul. Two experiments were made, with magnets upon nervous subjects, to see if the effects produced were really magnetic or due to the imagination. In the first experiment a piece of unmagnetised iron was shown to the patient, who immediately fell into convulsions. In the next experiment a magnet was placed in the hand of a nervous subject, who at the end of a few seconds became so over-excited that the magnet was removed. That the effect thus produced was due to the sight of the magnet was proved by hiding several powerful magnets in the chair occupied by the same individual, who when thus unconscious of their presence experienced no ill effect. M. Chevreul made some remarks apropos of the foregoing paper on certain other illusions, such as the divining pendulum and divining ring.-Remarks on recent researches concerning the explosion of powder, by MM. Roux and Sarrau. The authors pointed out the agreement between certain of the results obtained by them and by MM. Noble and Abel in their recent communications to the Academy.-New note on the tail of Coggia's Comet, by M. A. Barthelemy. The theory of a repulsive force emanating from the sun requires, according to the author, that the axis of the tail should always be a prolongation of the radius vector. With Coggia's Comet, however, as observed by M. Heiss on Jul? 5, the tail made an angle of 1600 with the radius vector. The facts appear to the author to be simply explicable by the hypothesis of an interplanetary medium submitted to the attractive action of the sun, through which medium the comet travels with an increasing velocity; fans and jets are supposed to be the result of the sun's attraction on the denser portions of the cometary matter.-On a new theory of the formation of comets and their tails, by M. Virlet d'Aoust. In 1835 the author suggested the hypothesis that comets were nascent stars-the internal and still incandescent portions shining through cracks in the dark surface. This view was afterwards abandoned for Saigey's hypothesis, which considered the tails of comets as the result of the reflection of [their light on an atmosphere which they drew after them. This opinion was again modified to meet the researches of Weiss, Schiaparelli, Klinker-fues, and Oppolzer, who showed the connection between the comets of 1862 and 1866, of Biela and Pogson, and the annular meteor streams which give us the August and November shooting stars. The author then asked whether comets did not equally belong to rings which had given rise to their existence, and if the light emitted by their tails did not simply result from the reflection of light from the nucleus on to the cosmical particles which constituted the rings on which they seemed to depend. The recent researches upon Coggia's Comet confirm this view in the author's opinion.-On a new model of prism for direct vision spectroscopes, by M. J. G. Hofmann.-On some points in the anatomy of the common mussel (Mytilus edulis), by Ms Ad, Sabatier.
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Societies and Academies . Nature 10, 394 (1874). https://doi.org/10.1038/010394b0
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DOI: https://doi.org/10.1038/010394b0