82 



NA TURE 



[July 15, 1909 



as 42° ; the coldest period is at the end of January, 12-5°, 

 and the warmest in the middle of July, 16-7°. The mean 

 temperature of the northern hemisphere, 15-3° C, is nearly 

 i\° higher than that of the southern. The work includes 

 seven isothermal charts between 30° and 90° S. latitude 

 for the year, for mid-January, and each alternate month. 



The Halbmonatlichcs Literaturverzcichnis of the Fort- 

 schritle dcr Physik, issue'', \inder the auspices of the 

 German Physical Society, still continues to furnish more 

 promptly than any other periodical a list of the papers 

 dealing with topics of interest to physicists which appear 

 in the various journals and proceedings of societies. As 

 instances of the promptness with which titles of papers 

 are published, we may mention that the number for 

 June 15 contains the titles of several papers read at the 

 meetings of the Royal .Society and of the Physical Society 

 of London in April and May. 



The prestige of the " principle of retativity " as a basis 

 for our treatment of electrodynamics in moving- media has 

 been increased by a preliminary communication made to 

 the German Physical Society by Dr. E. Hupka, an account 

 of which is given in the Vcrhaiidiuiigen of tlie society for 

 June 15. Three or four months ago Dr. A. H. Bucherer 

 announced that the results of his e.Kperiments on the inertia 

 of the negatively charged particles of the 3 rays from 

 radium were distinctly in favour of the principle as against 

 its most formidable rival the " sphere theory." Now Dr. 

 Hupka, working with the electrons produced when light 

 falls on negatively charged bodies, has shown that when 

 these electrons are accelerated by the action of an electric 

 field, and then deflected by passing through a magnetic 

 field, the deflections observed are again in favour of the 

 principle, which may be stated as follows : — The electro- 

 dynamic phenomena exhibited within two systems moving 

 with respect to each other in a straight line will follow 

 the same laws, provided that in each system the unit of 

 time be so chosen that the velocity of light is expressed 

 by the same number. 



" SUPPLEMENT.\RY I N VESTIG.MIONS OF InFRA-RED SpECTRA, " 



by Prof. Wm. W. Coblentz (parts v., vi., vii.), has been 

 received from the Carnegie Institution of Washington. 

 This publication contains supplementary data on the 

 doubtful points which arose in the author's preceding work, 

 and also some additional observations on the emission 

 spectra of metal filaments and insulators, thus rounding 

 up the subject as completely as possible at the moment. 

 Although, as Prof. Coblentz goes on to say, the pro- 

 gramme of investigation is completed, the subject is not 

 exhausted — not even thoroughly initiated. The value and 

 importance of the author's work in the infra-red region 

 of the spectrum are too well known to need any further 

 diploma of merit at this time ; moreover, it is impossible 

 to deal in detail with the account of the many new observa- 

 tions described in the present monograph. There are three 

 separate lines of work, namely, infra-red reflection spectra, 

 transmission spectra, and emission spectra. To these is 

 added a valuable chapter on the instruments and methods 

 used in the work. Two points of special interest may be 

 noted, one of which is the relation between the maxima 

 in the reflection spectra of the carbonates and the atomic 

 weight of the metal, where the maxima steadily shift 

 towards the red with increase in molecular weight. The 

 second point of interest is the infra-red spectra of the 

 colloidal metals in relation to the coloured glasses. There 

 IS no doubt that, quite apart from its general importance, 

 ■Prof. Coblentz 's work, owing to the range of spectrum 

 dealt with, w-ill have considerable bearing upon the relation 

 between absorption and chemical constitution. 

 NO. 2072, VOL. 81] 



A NEW form of gearing, which has been invented by 

 Mr. Jules Lecoche, and is being introduced by the Anglo- 

 Foreign Inventions Syndicate, Ltd., of 10 Camomile Street, 

 H.C., is illustrated in Engineering for July 2. The gear- 

 ing essentially consists of two wheels having spiral or 

 helical teeth which run out of contact, a mechanical clear- 

 ance of about I /32-inch separating the tops of the teeth 

 on the two wheels. One of the wheels is provided with 

 field magnets in such a way that a magnetic flux is 

 generated between its teeth and the corresponding teeth 

 on the other wheel. The mechanical drive is obtained 

 entirely by means of the magnetic flux, the form of the 

 teeth being such that, when the wheels are running 

 together, the tops of any two teeth in magnetic mesh lie 

 immediately one over the other, and follow each the same 

 path. As two teeth leave each other, the magnetic flux 

 will be transferred from the leaving teeth to the approach- 

 ing teeth, thus ensuring continuity of drive. As there is 

 no contact there can be no friction ; and as the power con-' 

 sumcd in the field coils is only about 3 per cent, of the 

 power transmitted, a gearing elHciency of about 97 per 

 cent, is attainable. Another advantage lies in the high 

 speed of transmission possible. Ball bearings are used 

 for the spindles, an example at present being shown in 

 London bv the Albany Engineering Company, of Ossory 

 Road, S.E., having a gearing loss of 179 per cent, and 

 an over-all efficiency of more than 90 per cent. The 

 advantages of this gear should open a wide field for its 

 applications. 



We have received a copy of the report of the Indian 

 ■■\ssociation for the Cultivation of Science for the year 1907. 

 The association arranges courses of lectures upon scientific 

 subjects, maintains a laboratory and library, and conducts 

 an annual examination of candidates for prizes and med'ils. 

 Interesting speeches were given at the annual meeting held 

 last November, and altogether the association appears to 

 be doing useful work in spreading a knowledge cf ind 

 interest in science. 



The July number of the Fortnightly Review contains an 

 article by Dr. Marie C. Stopes entitled " An Expedition 

 to the Southern Coal Mines." Dr. Stopes was sent by the 

 Royal Society for special paUcobotanical work to Japan, 

 where she spent a year and a half in close touch with the 

 Japanese. In addition to devoting a large part of her 

 stay to research work in the Imperial University, Dr. 

 Stopes travelled widely on tours of inspection and investi- 

 gation. She entered a great many of the coal mines in 

 Japan, and penetrated to the heart of the country search- 

 ing for interesting specimens. Her article is in the form 

 of a diary, not written for scientific workers, but intended 

 to supply a series of pictures of life in many parts of 

 Japan. 



OVR ASTRONOMICAL COLUMN. 

 Radial Motion in Sun-spot \'apours. — Referring to 

 some comments and queries, by Mr. Buss, in the May 

 number, Mr. Evershed gives further details of the radial 

 motion discovered in sun-spot vapours, in No. 411 of the 

 Observatory. He has found that when the slit of the 

 spectroscope does not bisect the spot symmetrically, but 

 crosses the penumbra on the side of the spot nearer to the 

 centre of the sun's disc, the lines are always convex towards 

 the violet ; whereas if the slit crosses the opposite side of 

 the penumbra they are convex towards the red. That the 

 line displacements are due solely to motion is shown by 

 the change in position angle of the maximum shift as the 

 spot traverses the disc. The maximum displacement is 

 always such as fo indicate that the maximum motion is 

 along the radius, but the observations are not yet sufli- 

 I ciently delicate to disprove the existence of a superimposed, 



