February 2, 1899] 



NA TURE 



335 



former frequently giving rise to brine springs and containing 

 salt deposits at Deninat in the Atlas, (c) The Upper Cretaceous 

 rocks, chiefly white and cream-coloured limestones, which 

 attain their greatest development on the plateau. (3) The Atlas 

 itself is made up for the most part of the same rocks. There is 

 a core of metamorphic rocks, which is better developed and 

 wider at the western end of the range and narrower towards the 

 east. Next comes the great development of the Lower 

 Cretaceous strata, followed by a diminutive representative of 

 the Upper Cretaceous rocks. These rocks are much broken by 

 folding and faulting, and their structure is displayed in several 

 sections taken across the range from Demnat westward. The 

 first signs of glacial action were met with at Titula, consisting of 

 moraine-like heaps of debris ; elsewhere, scratched stones were 

 found. 



Dublin. 

 Royal Dublin Society, December 21, 1898. — Prof. T. 

 Preston, F.R.S., in the chair. — Mr. J. E. Duerden, of Kingston, 

 Jamaica, communicated a paper giving an anatomical description 

 of ten species (seven Stichodacylino; and three Zoanthea;) of 

 Jamaican Actiniaria. A new genus, Heliktanltius, is erected 

 for the Actinia anemone of Ellis, and included along with the 

 genera Ricordea2.n& Actinoporus, under the family Discosomidae. 

 Three species of Parazoanthus are all new. — Prof. T. Johnson 

 gave an account of the different kinds of peat and their products, 

 including a set of continental specimens recently added to the 

 Botanical Department of the Science and Ait Mu.seum, 

 Dublin. — Prof. James Lyon presented a note on the reversal of 

 the photographic image, with lantern illustrations. — Dr. Gerald 

 MoUoy read a paper on the use of the vertical wire in Mr. 

 Marconi's system of signalling through space, by means of 

 electric waves. Mr. Marconi had found that by using a long 

 vertical wire in connection with the oscillator at the sending 

 station, and a similar wire in connection with the resonator ai 

 the receiving station, he was able to increase the distance over 

 which intelligible signals could be sent, from a few hundred 

 yards to fourteen miles and more. But the curious thing was 

 that the wire was quite ineffective if placed horizontally. To 

 account for this. Dr. Molloy proposed a theory, founded on the 

 principle of electric images. He showed that, whether the 

 wire was placed horizontally or vertically, the oscillations of the 

 discharge were accompanied by oscillations of the electric 

 image, anal that each .set of oscillations sent out waves 

 into space. But there was this difference between the two 

 cases : when the wire was horizontal, the waves sent out by the 

 oscillations of the image were in opposite phase to those sent 

 out by the oscillations of the discharge, and therefore tended to 

 extinguish them ; whereas when the wire was vertical, the two 

 sets of oscillations were in the same phase, and tended to 

 reinforce each other. — Mr. Ernest A. W. Henley presented a 

 preliminary note of a method of measuring the relative opacities 

 of various organic substances to the X-rays. He found the 

 numbers representing the relative opacities of bone, muscle, and 

 fat to be 4, 2'5, and i. These results were obtained by 

 comparing .\-ray photographs of wedge-shaped pieces of the 

 substances placed side by side, and finding two points, one in 

 each wedge, which had the same depth of colour. The thick- 

 ness of each wedge at the point found in it was measured, and 

 hence the ratio of the opacities was determined. — Prof. G. 

 F. Fitzgerald, F. R. S., read a paper on a hydrodynamical hypo- 

 thesis as to electromagnetic actions The paper is an attempt 

 to extend Lord Kelvin's papers on the propagation of laminar 

 motion in a turbulent liquid in the Phil. Mag., 1887, vol. xxiv. p. 

 342, and which he there illustrated by separate vortex rings in 

 the case of long vorte.x filaments, such as Lord Kelvin described 

 in a paper on vortex filainents surrounded by a tore (A'. /. 

 Acad. Proc, ser. iii., 1889, vol. i. p. 340). It appears as if 

 electric force should be represented by a helical condition of 

 the filaments, which would be propagated with another accom- 

 panying motion which represents inagnetic force. An electron 

 should then be the irregular point where two helices wound in 

 opposite directions meet. 



Paris. 

 Academy of Sciences, January 23. — M. van Tieghem in 

 the chair. —Some remarks on the prolongation of functions, by 

 M. Emile Picard. — On some properties of aluminium, by M. A. 

 Ditte. The results of experiments on the corrosion of aluminium 

 by saline solutions show that the metal is at first vigorously 

 attacked, but that a coherent protective layer of alumina is soon 

 formed. In presence of air, however, the corrosion goes on, 



NO. 1527, VOL. 59] 



and if an aluminium plate has been immersed in a salt solution 

 and then only imperfectly washed, the attack slowly continues, 

 the surface becoming more easily attacked by other reagents. — 

 Histology of the skin. Some histo-chemical reaction of 

 eleidine^ by M. L. Ranvier. The fragment of skin is left for 

 ten hours in a ten per cent, solution of common .salt, then 

 hardened in alcohol, and the sections stained with picrocarmine. 

 A uniform red tint is observed at the level of the stmliim 

 grantilosum, the granules of eleidine being coinpletely diffused. 

 In this way it can be shown that the epidermal cells lose their 

 granular eleidine sharply in passing from the stratum ^ranulomiu 

 into the stratum intermedium. — On the formation of pollen and 

 the chromatic reduction in A'ais major, by M. L. Guignard. 

 The numerical reduction appears only at the instant when the 

 pollen mother-cell commences to divide up into the four pollen 

 grains. During the first division of the mother-cell, each 

 chromosome splits twice longitudinally and becomes quadruple ; 

 during the second division, the our chromosomes already 

 formed are simply distributed equally between the four pollen 

 nuclei. — Researches on the chemical state of the elements 

 contained in steels. Double carbides of iron and other 

 metals, by MM. Ad. Carnot and Goutal. The carbides 

 Fe^CWC, FejCMojC, 2Fe3C.Mn^C, Fe3C.2Mn3C, and 

 Fe3C.4Mn3C were isolated from steels containing tungsten, 

 molybdenum, and manganese. — The first voyage of the 

 Princess .4/ice If., by Prince Albert I. of Monaco. A 

 resume of the scientific results of the voyage in the polar seas 

 during the summer of 1898. The majority of the specimens 

 were "collected in the northern Norwegian fjords and at Spits- 

 bergen.— Prof. Mendelejeff was elected correspondant in the 

 Section of Chemistry, in the place of the late Prof. Kekule.— 

 Observation of the total eclipse of the moon of December 27, 

 1898, made at the Observatory of Besan^on, by M. L. J. Gruey. 

 —Observations of the planet 1898 ED (Charlois), and of the 

 Chase comet, made at the Observatory of Besan9on, by M. P. 

 Chofardet, by M. L. J. Gruey.— On some photographs of 

 nebula? and star clusters, obtained at the Observatory of Meudon, 

 by M. Louis Rabourdin. The paper is accompanied by seven 

 reproductions of photographs of nebulae and of the great 

 Hercules star cluster. — Generalisation of Jacobi's first method 

 ofintegrating partial differential equations, by M. N. Saltykow. 

 —On groups of operations, by M. G. A. Miller. — On the 

 development of certain surds in continued fractions, by M. 

 Crelier.— On the deforination of some quadrics of revolution, by 

 M. C. Guichard.— On the normal equation of surfaces, by 

 M. A. Pellet.— On the expression of the energy of a circuit 

 and the law of the electromagnet, by M. A. Perot.— On the 

 chemical action of the X-rays, by M. P. Villard.— Action of 

 oxidising agents on some aromatic compounds, by MM. 

 (Echsner de Coninck and A. Combe. A continuation of work 

 previously described. Nitrogen gas was evolved on oxidation with 

 chromic acid in only one case, that of picramic acid. — Action of 

 iodine monochloride upon monochlorobenzene in presence of 

 anhydrous aluminium chloride, by M. A. Mouneyrat. Iodine 

 monochloride acts readily upon chlorobenzene in presence of 

 aluminium chloride at 60° C. The main product of the re- 

 action is ;>-iodochlorobenzene, small quantities of dichloro- 

 benzene and trichlorobenzene being obtained as bye- products.— 

 Studies in filtration ; organic liquids, by M. J. Hausser. 

 The filtering layer in these experiments was composed either 

 of kaolin, calcium phosphate, or animal charcoal. The 

 filtering layer was not changed by the successive pas- 

 sage of different liquids. The relative velocities of filtration 

 for a given liquid are not altered by a change in the filtering 

 material.— Biochemical oxidation of propane glycol, by M. 

 Andre Kling. Propane glycol is oxidised by the sorbose bacteria 

 to either acetol or pyruvic aldehyde, the osazone of which was 

 isolated.— On some cellular bodies in the organism of a verte- 

 brate, by M. P. Stephan.— Researches on the anal glands of the 

 Carabidae, by M. L. Bordas.— On the mechanism of flight m 

 insects, by M. Charles Janet.— Relations between the intensity 

 of the green coloration of leaves and assimilation by chloro- 

 phyll, by M. Ed. Griffon. It is not always possible to predict 

 the intensity of chlorophyllian assimilation by the intensity of 

 the green coloration in fully-developed leaves. In some cases 

 leaves having the same lint have different assimilating powers, 

 and in others the pale leaves may assimilate more strongly than 

 the darker leaves.— On the primordial leaves in Cupressus,hy 

 M. Aug. Daguillon.— On the structure of the bundles of the 

 placenta in the genus Primula, by M. E. Decrock. 



