200 



NATURE 



[December 7, I'ji i 



sometimeK intiiKJc, .souR-times pass Into the others, so they 

 also must have been nt high temperature. The so-called 

 " granites " at the two ends of Sark are hornblendic, the 

 southern one being really a tonalitc ; so are tliose of 

 Alderney, Herm, Jethou, and Gufrnsey, and it is suggested 

 that these granites may be yet more acid terms in a differ- 

 entiation series. Of thf numerous dykes, the most acid arc 

 either aplitic microgranitcs or quartz-felsites. Diabase- 

 dykes are common, and mica-traps have been found in all 

 the islands except Ilerm. At Pleinmont, in the south-west 

 of Guernsey, a mass resembling a greenstone proves to be 

 sedimentary. The time-relations of the several rocks are 

 discussed. The gneiss of Guernsey is the oldest, and had 

 acquired its structure before the intrusion of the diorites. 

 They were followed by the hornblendic granites, and these 

 by the aplitic microgranitcs. .Ml were prc-Cambrian. 

 The date of the diabase-dykes is more uncertain. The 

 mica-traps are probably late Pahtozoic. — H. Woods : The 

 evolution of Inoceramus in the Cretaceous period. The 

 species of Inoceramus found in the Gault, the Upper 

 Greensand, and the Chalk are considered to have descended 

 from two stocks which occur in the Lower Greensand, 

 one being /. salovnoni, d'Orb., the other of the type 

 of /. neocomtensis, d'Orb. (i) I. concentricus. Park. 

 (Lower and Upper Gault), is of the same type as 

 J. salomoni (Folkestone beds and Mammillatum bed), from 

 which it has been derived. /. sulcatus, Park. (Upper 

 Gault), closely resembles /. concentricus, except that it 

 possesses strong radial ribs. Between these two species 

 every gradation is seen. /. tenuis, Mant. (Red Chalk and " 

 Chalk Marl), is allied to 7. concentricus, from which it has 

 been derived by an increase in the length of the hinge and 

 a decrease in the prominence of the left umbo. 

 (2) /. anglicus. Woods (Gault and Upper Greensand), 

 resembles /. neocomiensis, but the posterior part of the 

 shell has become more compressed, and the ventral curva- 

 ture of the ribs has increased. From I. anglicus two 

 species appear to have arisen, namely, I. pictus and I. 

 crippsi. (a) I. pictus, Sow. (Chalk Marl to H. subglo- 

 bosus zone), approaches the form of I. anglicus, which has 

 more numerous and more regular ribs ; and in it the ribs 

 have become still more numerous and more regular, and 

 the anterior area has become more extensively developed. 

 (6) I. crippsi, Mant. (Upper Greensand to zone of H. sub- 

 globosus), agrees in many respects with the form of 7. 

 anglicus, which has fewer and less regular ribs ; but in 

 this species the hinge has become somewhat shorter, the 

 postero-dorsal part of the shell less compressed, the anterior 

 area smaller, the ribs fewer and more irregular, with a 

 less strongly marked posterior curvature. 



Cambridge. 

 Philosophical Society, November 13 — Sir George Darwin, 

 K.C.B., F.R.S., president, in the chair. — Sir J. J. 

 Thomson : Application of positive rays to the study of 

 chemical reactions. The author describes the results of 

 the application to chemical reactions of a method which he 

 brought before the notice of the society at a previous meet- 

 ing. The production of carbon monosulphide when an 

 electric discharge passes through the vapour of carbon 

 bisulphide was detected by this means. The author gives 

 the results of investigations on the chemical combination 

 between hydrogen and oxygen and hydrogen and nitrogen, 

 and discusses the source of curves corresponding to atomic 

 weights 1-6, 2-5. 20-21, 30, 50-51, which do not fit in 

 with recognised elements or compounds. — N. Bohr : 

 Electron theory of metals. In the paper an attempt is 

 given to generalise the theory of H. A. Lorentz, retaining, 

 however, the main assumptions used by this author. It is 

 shown that, by making alterations in the special assump- 

 tions used by Lorentz, results can be obtained for the 

 electric and thermal conductivities and for the galvano- 

 magnetic phenomena, which agree more closf^lv with the 

 experiments. On the other hand it is shown that the 

 calculation of the absorption and emission of heat rays 

 with long times of vibration in all the considered cases 

 leads to the same law of heat radiation as given bv 

 Lorentz, and that, further, the remarkable conformitv 

 between Lorentz 's calculation of the thermoelectric pheno- 

 mena and the thermodynamic theory of these phenomena 

 given by Lord Kelvin will remain unchanged in all the 



NO. 2197, VOL. 88] 



considered cases. Finally, it is shown thf»» **■"■ «-. . 

 of free electrons, contrary to the generally 

 will not give rise to any magnetic pr< 

 metals. — J. C. Chapman : Secondary chara< 

 Rdnt|gen radiation from elements of high atomic v 

 The secondary Ront)4<n radiation has been 

 lead which belongs to the more or less i- 

 group (group L, Harkia, Phil. Mag., Stjx- .. 

 gards its characteristic radiation. It was four ! 

 shows a marked homogeneous constituent n^ 

 the scattered radiation. A/p in Al=:i6-8 (I<=1 

 p = density of Al). The absorption by the clen'ent !■ 

 the form of lead oxide was measured for a series of 

 gf-neous beams of group K, and it was shown t 

 exhibits a marked selective absorption in t^- '—'■■• 

 it commences to be rxcited ; thus b^t 

 X/p=i8.5, and bromine, \!p=i6-2, the rati' 

 tion by lead to that by aluminium commences to ri*- 

 continues to do so until the absorption band is ; 

 This would suggest that the mechanism of productii 

 the resulting radiation in both groups is of the sam^ 



Edinburgh. 



Royal Society, November 13. — Prof. J. C. 1 

 F.R.S., in the rhair.^-Angus B. FMiton : Experim- 

 show how failure under stress occurs, its cause, an-' 

 parative values of the maximum stresses induced 

 timber is fractured in various ways. The objects 

 research were to study the effects of the medullar 

 on the strength of timber when strained in various 

 and to connect up the maximum induced stresses in 

 bending with those obtained in tension and compr^ 

 Some of the conclusions arrived at were that the 

 cause of fracture lies in the medullary rays ; tha' 

 angular beams when laid on a tangential face are 

 and have a higher fracture value than when laid 

 radial face ; that rectangular beams of unequal sid 

 stiffer, but not materially stronger, when laid on the 

 side of the section ; that fracture by shearing does n* 

 place in timber beams of the commoner woods, su; 

 on the two ends and loaded in the middle, where th 

 of span to depth of beam exceeds seven. — Dr. G. R 

 ford Jeffrey : A new method of measuring ment 

 cesses in normal and insane people, with special re^ 

 to maniac depressive insanity. The object of the n 

 was to ascertain whether or not any definite charac 

 of the mental working process could be detected 

 disease, or group of diseases, described as mani 

 pressive insanity. The reckoning test, recently d< - 

 by Maloney, was used. The test consisted of the .i' 

 of digits in pairs, each pair being taken to repre- 

 constant unit of mental work. Not only was the n 

 of units of mental work done throughout a given 

 ascertained, but also the number of units per ■ 

 throughout the same period. The number per mir- 

 these mental units was then plotted against the tirr, 

 a curve obtained showing objectively the mental w 

 capacity throughout the period. The experiment co 

 in allowing thirty cases of maniac depressive insai 

 perform the reckoning test for fifteen minutes on e 

 five successive days. Seven normal people v 

 under the same conditions and for the sam- 

 time. An average normal mental cur\-e was 

 this way, and this was compared with the cur\ 

 from the insanity cases already mentioned. 1 

 curve did not support Hylans's assertion that the 

 period of five minutes represented best the ma\ 

 working capacity. .As compared with the normal 

 the work curve of the maniac depressive cases d 

 markedly in two ways : — (i) a tendency town' 

 output characterised the third five-minute intr- 

 the author regarded as being probably due to tl 

 which such patients experience in getting under wf 

 the mental task, and as being an expression f^*^ 

 exaggerated psycho-motor inei^ia ; (2) the sma!" 

 the terminal spurt, possibly due to the fa< 

 imminence of the end of the task, which act- 

 centive to greater effort in normal people, is i" 

 The curves varied in form according .is the pa: 

 in the quiescent, depress^, or excited phases of th< 

 disease. For example, in the depressed patient's chart. th< 



