454 



NATURE 



[August 8. 191 8 



tion of the industry in this country, with the view of 

 preventing overlapping of effort. A full account is 

 given of the addresses delivered by Lord Sydenham, 

 Sir Algernon Firth, and Sir Henry Newbolt at the 

 annual meeting on June 19. The offices of the Guild 

 are at 199 Piccadilly, London, W.i. 



Mr. Bernard Quaritch, having acquired the stock 

 of " Biologia Centrali-Americana " from Dr. F. Du Cane 

 Godman, is offering the work, either complete or in 

 separate sections, at reduced prices. A prospectus 

 explaining the orif*in and development of the " Bio- 

 logia Centrali-Americana," and giving particulars of 

 the contents of each of the sixty-three volumes, has 

 been prepared by Mr. Quaritch, and will be sent to 

 readers of Nature upon application being made for it 

 to II Grafton Street, New Bond Street, W.i. 



OUR ASTRONOMICAL COLUMN. 



The Perseid Meteoric Shower. — ^The maximum of 

 this brilliant annual meteoric shower will probably 

 occur on Sunday night, August 11, and the best period 

 for observation may be expected after midnight. The 

 first traces of the shower were recognised on July 8 

 by Mrs. Fiammetta Wilson at Totteridge and by Miss 

 A. Grace Cook at Stowmarket. A meteor was 

 mutually recorded by them on that date and found to 

 be a true Perseid, with a radiant point at 8°+49°. 

 Another member of the stream was seen by the same 

 observers on July 12, and the activity of the display 

 has been increasing nightly. On August 5, at 13-54 

 G.M.T., a splendid Perseid brighter than Venus was 

 seen by Mr. Denning at Bristol traversing a path 

 from 269° + 84|° to 23o°+65°. With suitable weather 

 there should be a rich display of Perseids this year. 



Radial Velocity of jSCanis Majoris. — Tn 1908 the 

 star /3 Canis Majoris, of magnitude 20 and type Bi, 

 was found by Albrecht to be a spectroscopic binary 

 with the very short period of about six hours. A 

 further study of the star has recently been made by 

 Dr. F. Henroteau, in which special efforts were made 

 to secure continuous series of plates during the same 

 revolutions (Lick Obs. Bull., Np. 311). The mean 

 velocitv, of +35 km. per second, appears to be con- 

 stant, but the range of velocity has been found to vary 

 very considerably from one period to another, being 

 sometimes as low as 3 km., and at other times as 

 much as 18 km. per second. This variation in range 

 shows no simple periodicity, but does not seem to be 

 a discontinuous function. It is remarkable that while 

 there is no period which connects and represents the 

 different minima of velocities, a period of 025714 dav, 

 starting from a given maximum, always corresponds 

 with either a maximum or a minimum of the velocity 

 curve. It has been further noted that the spectral 

 lines undergo a periodic change in width, the ampli- 

 tude being always aooroximately the same, and the 

 period 025130 day. This variation seems more likely 

 to be due to phvsical changes in a single bodv than 

 to the combination of two spectra, but no satisfactory 

 explanation of all the peculiarities of the star has yet 

 been found. Adopting Mitchell's parallax of +oooq", 

 the, star would "Tie about 1000 times as bright as the sun. 



Relativity. — A paper by Jun Ishiwara on relativity 

 (Proceedings of the Tokyo Mathematlco-Physlcal 

 Socletv, second series, vol. ix., No. 16, May, 1918) is 

 based on the assumption that the gravitation potential 

 is completely represented by a scalar quantity ^|/■; the 

 components ^'m- of the fundamental tensor of the time- 

 space transformation and the scalar c (velocitv of 

 light in vacuo) are functions of \l/. It follows that the 

 field-Intensity is given by the gradient of rjr in space. 

 The expressions for sf^i- and c in terms of \|/- are found 

 with the aid of Polsson's equation, and the author 

 NO. 2545, VOL. lOl] 



deduces in an iftdependent manner the same expression 

 for the advance of the perihelion of a planet during 

 one revolution as that already given by Gerber and 

 Einstein, which is known to agree with the observed 

 value in the case of Mercury. 



Dr. L. Silbersteln demonstrates in Monthly Notices 

 of R.A.S. (May, 1918) that an unexpected consequence 

 of Einstein's theory is that all homogeneous bodies 

 must be spherical ; he considered that this was a 

 strong argument against the truth of Einstein's views. 

 Prof. Eddlngton, In the discussion which followed, 

 remarked that the principal bodies known to us in 

 space do, in fact, approach very closely to the spherical 

 form, and, further, that a perfectly homogeneous body 

 Is difficult to conceive, since there must be some 

 differences of pressure, and therefore of density, in 

 different portions of It. 



THE SUPPRESSION OF BODY-VERMIN. 



A COMPREHENSIVE "paper entitled "Combating 

 Lousiness among Soldiers and Civilians," by Prof. 

 G H. L. Nuttall, appears in Parasitology for May 

 (vol. X., No. 4). The paper Is one of a series which, 

 when complete, will constitute an exhaustive mono- 

 graph on human lice. It brings together, not only 

 the available published Information, but also that re- 

 sulting from hitherto unpublished research work, 

 partly the author's own, and partly that of others 

 contained in reports«to the War Office, which he has 

 been permitted to use. Prof. Nuttall has generously 

 presented a special edition of three hundred copies of 

 the paper to the Allied Armies ; and. In view of the 

 recently established fact that trench fever is conveyed 

 by lice, this should prove a very timely gift. 



The paper comprises 176 pages, with four plates and 

 twenty-six figures in the text. Most of the pages are 

 devoted to the practical consideration of louse destruc- 

 tion, a great deal of the experimental evidence being 

 given in detail. The results obtained demonstrate 

 that nits are killed by dry heat at 65°-7o° C. in one 

 minute, and at 55°-6i° C. In ten minutes, the active 

 stages being killed by dry heat at 65^-70° C. in one 

 minute and at 55° C. in five minutes. After allowing 

 for a margin of safety in practice, immersion in hot 

 water at 70° C. for a minute or two is amply sufficient 

 to destroy lice, while ''e° C. for ten minutes is equally 

 effective, a point of great importance in relation to 

 the washing of flannel garments. 



Singeing, sun-baking, and the use of hot flat-irons 

 are briefly dealt with. The various methods devised 

 for dlslnfestation by hot air and steam are treated of 

 at length, and illustrated by text-figures of disinfestors 

 Improvised for war purposes, together with plates de- 

 picting the more elaborate forms of dislnfectors de- 

 signed for use in peace-time. We agree with the 

 author that apparatus designed with a view to high 

 efficiency against the resistive spores of bacteria is 

 not adapted for rapid and economical use against lice. 

 It should be replaced by more commodious hot-air and 

 steam huts, or disinfestors planned on the improvised 

 railway vans said to have been so successful in the 

 East. Designs of this type of chamber should also 

 be adapted for steam or motor lorries, as well as. 

 trailers, which could, if necessary, be horse-drawn. 



Steam gives results superior to hot air If the destruc- 

 tion of pathogenic bacteria is an object, but dry heat 

 possesses many advantaj^es over steam if the destruc- 

 tion of body-vermin is the end in view. The use of 

 sulphur Is treated of at some length. We endorse the 

 author's remarks as to the failure of sulphur vapour 

 to destroy all the nits exposed to It, while its relatively 

 high cost, the danger of Iniurv to clothing, and its 

 slow action are further disabilities of the method. 



