iS 



NATURE 



[March 7, 19 18 



the number last session was 1240. This number in- 

 cluded 121 members of H.M. Naval and Military 

 Forces, for whom special courses were provided, and 

 159 who attended special vacation courses, so that the 

 actual number of ordinary students was ,960, of whom 

 547 were women. The report points out that, while 

 the normal fee revenue iunounts to between 29,000/. 

 and 30,000/. a year, the fee revenue last j^ear was only 

 14,000/. Economies of every kind have been intro- 

 duced, and all expenditure possible has been deferred. 

 It is anticipated that*, unless further help from the 

 Treasury is forthcoming, there will be a deficit at the 

 end of the current session of nearly 9000.'. 

 on the college establishment account. While 

 the ordinary activities of the college have been 

 maintained, all available energies have been 

 ■directed towards war purposes, of which the report 

 gives some account. Among the important develop- 

 ments of the year niay be noted the admission of 

 women to the faculty of medical sciences, the reorgan- 

 isation of the department of Italian, the institution of 

 a department of Scandinavian studies, and a movement 

 for the institution of a department of Dutch studies. 

 The pro patria list includes about 2500 names of past 

 and present members of the college who are taking 

 an active part in one or other of the Services connected 

 Avith the war. Of these no fewer than 195 have already 

 fallen. The list of honours and distinctions gained in 

 the war is a long one. 



s()(ih:rih:s axd academies. 



London. 

 Royal Society, February 21. — Sir J. J. Thomson, presi- 

 dent, in the chair. — Lord Rayleigli : The scattering of 

 light b}- spherical shells, and by complete spheres of 

 periodic structure, when the refractivity is small. The 

 problem of a small sphere of uniform optical quality 

 has been treated in several papers. In general, the 

 calculations can be carried to an arithmetical conclu- 

 sion only when the circumference of the sphere does 

 not exceed a few wave-lengths. But when the relative 

 refractivity is small enough, this restriction can be dis- 

 pensed with, and a general result formulated. In the 

 present paper some former results are quoted, but the 

 investigation is now by an improved method. It com- 

 mences with the case of an infinitely thin spherical 

 shell from which the result for the complete uniform 

 sphere is derived by integration. Afterwards applica- 

 tion is made to a complete sphere of which the struc- 

 ture is symmetrical, but periodically variable along the 

 radius, a problem of interest in connection with the 

 colours, changing with the angle, often met with in the 

 organic world. — Sir Joseph Larmor : The nature of heat 

 as directly deducible from the postulate of Carnot. 

 The germinal idea which developed, in the mind of 

 Sadi Carnot in 1S24, into the dynamical theorv of heat 

 was that heat can give rise to motive power only in 

 the process of carrying through its effort towards an 

 equilibrium. A proof is now offered that Carnot's 

 principle regarding heat-engines follows from this basic 

 Idea by itself alone, without requiring the introduction 

 of any hypothesis as to the physical nature of, heat. 

 It then further follows, from applying the same Carnot 

 formula both to direct and to reversed working, that a 

 scale of measurement of heat can be assigned, i.e. an 

 ideal calorimetric substance can be chosen, so that the 

 heat which disappears shall be the equivalent of the 

 motive power that is gained, and converselv — that is, 

 it follows that heat must itself be a form of energy. 

 But a limiting case of this general result requires 

 separate statement from the physical point of view, viz. 

 the ratio of equivalence between heat and work mav be 

 so small that practically the heat is conserved as if it 

 were a substance, and then the work may be said to 

 NO. 2523, VOL. lOll 



be done by its fall to a lower potential, strictly ;r 

 the analogy of the fall of water to a lower I( \ 

 Finally, a second absolute stale of measurement, th 

 of the potential or temperature of heat, may be phuM n 

 which reduces the thermodynamic relations to iIt 

 standard simple form. It is also remarked that ih. 

 original Carnot idea involves immediately the compli ti 

 foundation of chemical physics as applied to isotherm:!! 

 processes;- for under isothermal conditions it ass(r:- 

 that the interchanges of heat that occur during physi( ii 

 or chemical transformations do not enter at all i 

 the interchanges of motive power — that is, of i.sothei - 

 available energy. But physical knowledge was i 

 wide enough for a dozen years after 1824 to enable any 

 general survey of the energies of Nature to be thought 

 of; and when the principle of the conservation and 

 interchanges of total available energies came into the 

 light through the theoretical explorations of Faraday, 

 J. R. Mayer, and Helmholtz, and especially the prac- 

 tical experimental work of Joule, founded mainly on 

 the relations of energy to heat, the Carnot restriction 

 to uniform temperature was tacitly involved, though not 

 overtly expressed until lat-er. As a chapter in scientific 

 method, it seems, desirable to bring into view, even 

 now, the full potentiality that was latent nearly a 

 centur\-agoin the single creative idea of Carnot. — J. J. 

 Guest : Curved beams. Previous investigations upon 

 the stresses produced in a curved beam by a bending 

 moment have not resulted in solutions satisfying the 

 necessary elastic relationships. The author first treats 

 the case of a beam which is narrow in proportion to 

 its depth, obtaining expressions for the displacements 

 and principal stresses. The results are then thrown 

 into forms suitable for calculation. For the case of a 

 wider beam the author then shows that for the third 

 principal stress to be zero, both the inner and outer 

 surfaces of the beam section must curve in a, definite 

 manner, depending upon the value of Poisson's ratio 

 for the material used. The rigorous solution for the 

 case of a very wide beam compelled by restraints to 

 preserve n cj'Hndrical form as it bends is then given. 

 The paper concludes with a semi-graphical method for 

 estimating the maxim'um stress occurring in other 

 cases, that of a beam of circular section being worked 

 out for different values of the curvature. — Dr. A. E. H. 

 Tutton : Monoclinic double selenates of the iron group. 

 In this memoir are described the results of a complete 

 investigation of the crystals of the potassium, rubidium, 

 caesium, and ammonium salts of the iron group of 



double selenates of the series RaM^g^oA.eHaO. The 



outstanding result is to confirm the conclusions 

 drawn from the previous study of three other groups of 

 double selenates, and of eight groups (the complete set) 

 of double sulphates. The general law of progression 

 of the crystallographic properties, with the atomic 

 weight and atomic number of the interchangeable 

 alkali metals which form the group, is obeyed abso- 

 lutelv rigidly by the iron group.— Dr. A. E. H. Tutton : 

 Selenic acid and iron. Reduction of selenic acid by 

 nascent hydrogen and hydrogen sulphide. Preparation 

 of ferrous selenate and double selenates of iron group. 

 Some new properties of selenic acid have been ob- 

 served. Instead of dissolving iron with evolution of 

 hydrogen like sulphuric acid, selenic acid is without 

 appreciable action on iron. After a very long time the 

 latter becomes thinly coated with red selenium due to 

 reduction of a trace of the acid by nascent hydrogen 

 produced in the slight action which occurs. After 

 attempts spreading over eight years the author has at 

 last obtained K2Fe(Se04),,6H20 crystals during four 

 of the very cold nights of January, 1918, when the 

 laboratory temperature fell to nearly 0° C. and never 

 rose above 2° C. Above this temperature the salt is 

 unstable. The cn'stals were pale green, well formed. 



