January 6, 191 6] 



NATURE 



529 



of a deciduous tree has a greater pressure than that 

 from the root and lower portions. The excess is 

 greatest in early spring, when the sugar content be- 

 comes very considerable, though appreciable quantities 

 of sugars, mainly sucrose, are always present. The 

 electrolytes increase noticeably in late spring. In ever- 

 greens a more uniform distribution of osmotic pres- 

 sures is found in the stem, and the seasonal changes 

 are not so sharp. 



Edinburgh. 



Royal Society, December 6, 19 15. — Dr. John Home, 

 president, in the chair. — C. Tweedie : The Geometria 

 organica of Colin MacLaurin. This was a presenta- 

 tion in modern form of MacLaurin 's treatise on the 

 properties of plane curves, a treatise which was much 

 admired by Newton. With the exception of the French 

 school of geometers, mathematicians had largely neg- 

 lected this work of MacLaurin, who had enunciated 

 theorems and established relations which are usually 

 ascribed to later workers. In presenting the treatise 

 in English dress Mr. Tweedie had greatly simplified 

 the analytical methods, but had left practically un- 

 touched the geometrical reasoning, which for elegance 

 and lucidity could not be surpassed. — Prof. K. J. 

 Harvey-Gibson and Miss M. Bradley : The anatomy of 

 the stem of the Papavcraceae. This was the first of a 

 series of careful investigations into the characters of 

 plants belonging to the lower Dicotyledons. Through- 

 out the Papaveraceae the stem structure was very 

 uniform, the chief characteristics being- (a) a sub- 

 ' j)idermal band of chlorophyll-bearing tissue, (h) a 

 -clerotic pericycle (with some exceptions), (c) a mas- 

 sive pith, often fistular. — W. E. Collinge : A small col- 

 lection of terrestrial Isopoda from Spain, with descrip- 

 tions of four new species. The collection was from 

 the Cambridge University of Zoology, and the author 

 was indebted to the kindness of Dr. Leonard Don- 

 caster for the opportunity of examining it. There 

 were seven species, of which four were certainly new, 

 but two were too imperfect to admit of identification. 

 The new species were Porcellio batesoni, P. ex- 

 planatus, Artnadilliditim nitidulus, and Cnbaris in- 

 venustus. 



December 20, 1915. — Dr. John Home, president, in 

 the chair. — E. G. Ritcliie : The torsional vibrations of 

 beams of commercial section. In beams of circular 

 section the torsional rigidity depends on the polar 

 moment of inertia of the area. For non-circular sec- 

 tions de St. Venant had proved that important correc- 

 tions must be applied. In a previous paper Mr. Ritchie 

 showed that the effective moment of inertia to be 

 used instead of the polar moment of inertia in beams 

 of commercial section, such as the I-section, the 

 Channel, the Tee, the Angle, could be e.xpressed in 

 the form A"/tn, where A is the area of section and 

 n and tn are constants depending upon the type of 

 section. In the present paper, experiments on the 

 torsional vibrations of loaded beams of commercial 

 section were carried out and the results compared 

 with the theoretical values indicated. The compari- 

 sons were satisfactory. — E. H. Cunningham Craig : 

 The origin of oil shale. .After a detailed discussion of 

 the field evidence regarding the occurrence of oil 

 shales and oil fields in difTerent parts of the world, the 

 author elaborated a new theory of the origin of oil 

 shale, the main points of which were as follows : — 

 Kerogen is formed by the inspissation of petroleum, 

 <iuring which the nitrogen and sulphur conipoupds 

 become concentrated in the most inspissated or 

 weathered products. .At a certain stage of inspissa- 

 tion, which is reached gradually, the organic matter 

 becomes insoluble in carbon disulphide and ceases to 

 be bitumen. An oil shale is formed by the power of 

 certain clays or shales of absorbing and adsorbing 



NO. 2410, VOL. 96] 



inspissated petroleum, particularly unsaturated hydro- 

 carbons. — Dr. Thomas Muir : The theory of circulants 

 from/ 1880 to 1900. 



Paris. 

 Academy of Sciences, December 20, 1915. — M. Ed. 

 Perrier in the chair. — G. Bigourdan : Jean de Ligni^res, 

 his nationality and work. — Edouard Branly : The con- 

 ductivity of a thin layer of air between two metallic 

 surfaces. Details of experiments on the conductivity 

 of thin layers of air, of known thickness, for con- 

 tinuous currents. — G. Gouy : The form of the 

 X-rays. A theoretical examination of the problem of 

 the production of real foci of the X-rays, by the aid 

 of crystalline reflection. — M. de Sparre : The trajectory 

 of projectiles thrown with a great initial velocity with 

 an angle of projection in the neighbourhood of 45°, and 

 under the influence of the diminution of the density 

 of the air. — J. Guillaume : Observations of the Taylor 

 comet, made with the Briinner equatorial of the Lyons 

 Observatory. Two positions are given for December 

 II, one for December 13. On December 6, the comet 

 showed as a nebulosity of about i', with slight central 

 condensation. Magnitude, 9-5 ; colour bluish. On 

 December 11 it appeared brighter; magnitude not 

 under 6. — Paul Bruck : Observation and first elements 

 of the- Taylor comet. — Nicolas Kryloff : The converg- 

 ence of quadratures. — Marcel Brillouin : The problems of 

 mathematical physics and their general numerical solu- 

 tion. A method of constructing series which lead to 

 the numerical calculation of solutions of all problems 

 of mathematical physics defined by one or more linear 

 partial differential equations, whatever the form of the 

 limiting surface. — A. Targonski : The value of the 

 charge of the electron deduced from the calculation 

 of Brownian deviations. A comparison of Millikan's 

 method, based on the Stokes-Cunningham formula, 

 and that based on the observation of Brownian motion. 

 Leaving out of account experiments where the par- 

 ticles have been produced in the electric arc, the results 

 obtained by the two methods agree better when the 

 mean free path of the molecules of the gas is large 

 relatively to the radius of the particle observed. — 

 Gabriel Sizes : Complement of the law of resonance of 

 sonorous bodies. — Jean Danysz and Loais Wertenstein : 

 An attempt to influence the velocity of radio-active 

 transformations by the a rays. From the results of 

 the experiments described it is concluded that even 

 encounters with a particles with atoms are powerless 

 to provoke an artificial radio-activity, or a premature 

 transformation of the atom struck. — .Albert Colson : 

 Contradictions between the found and calculated solu- 

 bility of certain sodium salts. — B. Bogitch • The solidi- 

 fication curve of -the svstem ammonium nitrate — lead 

 nitrate.— L. Tschugaefl and J. Tschernjaeff : The 

 series of triamino-aquo salts of bivalent platinum 

 (Pt.3NH„H,0)X,.— M. Deprat : The discovery of the 

 Middle and Upper Cambrian in Tonkin, in Kwong-Si, 

 and in southern Yunnan. — C. Sauvageau : The hetero- 

 gamic sexuality of Saccorhiza hulbosa. 

 New South Wales. 

 Linnean Society, October 27.— Mr. .A. G. Hamilton, 

 president, in the chair. — R. Etheridge, Jun., and J. 

 Mitdiell : The Siluran trilobites of New South Wales, 

 with references to those of other parts of Australia. 

 Part v., Encrinuridae. The genera of the family are 

 briefly referred to in a general way, and the foreign 

 history of the genus Encrinurus is reviewed. — 

 E. W. Ferguson : Revision of the Amycterides. Part iv., 

 Sclerorinus (Section i.) [Coleoptera : Amycteridae]. 

 The total number of species recognised is sixty-one. 

 Section i. comprises one group of nineteen species, of 

 which two are described as new. This group is 

 strongly represented in South Australia, extending, on 

 the east, into the coastal and mountain districts of 

 Victoria and Tasmania. — R. Greig-Smith : Contribu- 



