May 2, 1 901] 



A' A TURE 



Dr. J. N. Langley, F. R.S., is re-appointed deputy-professor 

 of physiology until Michaelmas 1903, in the place of Sir M. 

 Foster, M.P. 



Mr. R. T. SMiiit has been appointed principal of the 

 Northern Polytechnic Institute. He organised and equipped 

 the South African College, Capetown, and acted as professor of 

 mathematics and physics in the College for several years ; and, 

 more recently, was lecturer in mathematics and physics in the 

 Goldsmiths' Institute, New Cross. 



The Secretary of State for War has appointed a committee 

 to consider the education of candidates for commissions in the 

 Army and the system of training at Woolwich and Sandhurst, 

 and to report whether any changes are desirable in the present 

 methods of entrance into the Army. The following will form 

 the committee: — The Right Hon. A. Akers-Douglas, M.P. 

 (chairman) ; the Rev. Dr. Warre, headmaster of Eton ; Mr. 

 F. W. Walker, high master of St. Paul's School, Hammer- 

 smith ; Colonel Jelf, C.M.G , Royal Engineers; Lieutenant- 

 Colonel Hammersley, Lancashire Fusiliers ; Captain Lee, M.P., 

 late professor of strategy and tactics, Royal Military College, 

 Canada ; and Captain W. E. Cairnes, Royal Irish Fusiliers 

 (secretary). 



Advocates of improvements in geometrical teaching will be 

 glad to know that the Civil Service Commission has lately 

 introduced a change of importance to all who are concerned 

 with Civil Service examinations. Before this year an instruction 

 at the head of examination papers in geometry stated that 

 " Proofs other than Euclid's must not violate Euclid's sequence 

 of propositions. " Upon recent papers, however, this has been 

 superseded by the note that " Correct demonstrations, whether 

 those of Euclid or not, will be accepted." It thus becomes 

 possible for teachers preparing pupils for the Civil Service to be 

 independent of Euclid's sequence or proofs. Recent questions 

 also encourage teaching of a less abstract character than that 

 usually associated with Euclid's geometry. We understand 

 that the Board of Education will accept alternative proofs of 

 propositions in future examinations in geometry. 



SOCIETIES AND ACADEMIES. 

 London. 

 Physical Society, April 26. — Dr. R. T. Glazebrook, 

 foreign secretary, in the chair. — A paper on the thermodynamical 

 correction of the gas thermometer was read by Prof. H. L. 

 Callendar. This paper commences by giving a short historical 

 sketch of the thermodynamic correction of the gas thermometer, 

 describing some of the solutions to Thomson's fundamental 

 equation for the Joule-Thomson plug experiment. The assump- 

 tions made in the. solutions have sometimes been erroneous and 

 wrong corrections have been obtained. From 1885 to 1 888 

 Chappuis made a series of careful comparisons between various 

 gas thermometers and a very delicate mercury thermometer, and 

 drew up a table of differences between the hydrogen and the 

 nitrogen thermometer. The author has taken the observations 

 of Chappuis and calculated a new table of differences. The 

 index " « " in the modified Joule-Thomson equation is not con- 

 stant. For steam it is about 3 '5 and for carbonic acid about 

 2. The thermodynamic correction is very small, especially in 

 the case of hydrogen and helium, and is very much less than 

 the correction for the expansion of the thermometer bulb. 

 Prof. Herschell asked whether the co-volume came into the 

 correction. Dr. Harker looked forward to the experiments 

 which Prof. Callendar proposes to make with a constant pressure 

 thermometer. The chairman expressed his interest in the ex- 

 treme delicacy of the observations of Chappuis. — A paper on 

 the production of a bright-line spectrum by anomalous disper- 

 sion and its application, the " flash-spectrum," by R. W. Wood, 

 was read and experimentally illustrated by Mr. Watson. It 

 has been suggested by W. H. Julius that the " flash-spectrum 

 seen immediately at totality may be due to photosphere light 

 abnormally refracted in the atmosphere of metallic vapours 

 surrounding the sun. The light which will be thus abnormally 

 refracted will be of wave-lengths almost identical with the wave- 

 lengths which the metallic vapours are themselves capable of 

 radiating. The sun is supposed to be surrounded by an atmo- 

 sphere of metallic vapours, the refractive index of which de- 

 creases with increasing distance from the surface. In this 

 atmosphere the rays of light coming from the photosphere move 



NO. 1644, VOL. 64] 



in curved paths. The refractive index is, however, very small, 

 except for wave-lengths very near those absorbed by the vapour, 

 consequently the light which resembles that emitted by the 

 vapours, is most strongly refracted, and therefore curves suffi- 

 ciently to reach us after the photosphere has been hidden by 

 the moon. The flash-spectrum of sodium was shown by 

 focussing the light of an arc lamp on a horizontal slit in front 

 of a flat metal plate supported so that the plane in which its 

 under-surlace lay coincided with the plane of the slit. At a 

 distance of about two metres a direct vision spectroscope wa.s 

 arranged to give a vertical spectrum and placed at such a 

 height that the prism barely caught the rays coming from the 

 slit and grazing the plate. On looking into the spectroscope a 

 bright continuous spectrum is seen. A Bunsen burner was then 

 placed underneath the metal plate and fed with sodium. This 

 produced a layer of sodium vapour of varying refractive index. 

 On raising or lowering the spectroscope bright sodium lines are 

 seen due to anomalous dispersion. By arranging screens these 

 lines can be obtained so that, on cutting out the arc lamp, the 

 flash-spectrum vanishes. Prof. Herschel expressed his in- 

 terest in the experiments and their application to the case of 

 the flash-spectrum seen at totality. 



Academy of Sciences, April 22. — M. Fouque in the chair. 

 — On the residues, and periods of double integrals of rational 

 functions, by M. limile Picard. — On an apparatus designed to 

 move the photographic plate which received the image furnished 

 by a siderostat, by M. G. Lippman. In an image given by a 

 siderostat only one point is really fixed, the other points appear- 

 ing to move round this with a variable velocity. It is shown . 

 that a suitable motion can be given to the photographic plate- 

 capable of overcoming this defect by means of a gear driven by 

 the clockwork of the siderostat. — On the existence of nitrides, . 

 argonides, arsenides and iodides in crystalline rocks, by- • 

 M. Armand Gautier. The finely powdered granites and basalts 

 were decomposed by heating at 100^ with phosphoric acid. 

 Determinations are given of the amount of nitrogen, arsenic and 

 iodine in various rocks. — Comparison of the work done by a 

 muscle in sustaining and lifting a charge, by M. A. Chauveau. 

 — On the propagation of discontinuities in a viscous fluid ; ex- 

 tension of the law of Hugoniot, by M. P. Duheni. — On a 

 question relating to a displacement of a figure of invariable size, 

 by M. R. Bricard. — On entire functions of several variables and' 

 their modes of growth, by M. Emile Borel. — Some isotherms 

 of ether between 100° and 206°, by M. Edouard Mack. The 

 pressure of the ether vapour was balanced by a piston floating 

 on a very viscous liquid, and the volume of the ether, which- 

 was completely surrounded by a mercury bath, was deduced 

 from the motion of the piston. — Cryoscopic researches, by 

 M. Paul Chroustchoff. An account of some of the precautions 

 necessary in applying the platinum thermon-ieter to the 

 measurement of the lowering of the freezing-point of dilute 

 solutions. — On a new system of ammeters and voltmeters- 

 independent of the intensity of their permanent magnets, by 

 M. Pierre Weiss. In an instrument of the d'Arsonval type 

 a decrease in the strength of the permanent magnet cause.=;- 

 a decrease in the sensibility of the instrument ; in instru- 

 ments having a movable magnetic needle controlled by 

 a permanent magnet the opposite is the case. If, in an instru- 

 ment of the moving coil type, the coil carries a small piece of soft 

 iron, these two effects may be made self-compensating. It was 

 found possible to construct a galvanometer of this type in which 

 the sensibility was practically invariable. — On the influence 

 of self-induction upon spark spectra, by Mr. G. A. Hemsalech. 

 Three photographs are given showing the progressive changes 

 produced in the spark spectra of cobalt, lead and magnesium by 

 an alteration in the self-induction of the spark circuit. — Periodic 

 oscillations productions by the superposition of an alternating 

 current on a continuous current in an electric arc, by M. E. 

 Kcenig. — On an apparatus which imitates the effect of luminous 

 fountains, by M. G. Trouve. — On barium hydride, by M. Guntz. 

 Barium hydride, the existence of which was first indicated by 

 Winkler, has been obtained in a pure state and found to have 

 the composition BaH.,. This compound is of remarkable 

 stability ; it can be slowly sublimed in a current of hydrogen at 

 1400° C. without decomposition. Heated in a current of nitrogen, 

 barium nitride is formed. — The estimation of nitric acid in waters 

 by means of stannous chloride, by M. H. Henriet. The fact 

 discovered by Divers and Haga that nitrates react with stanncms 



