40 



NATURE 



[July 8, 1909 



and they cover all the vessels previously classed by the 

 society excepting the large Cunard steamers Lusitania and 

 Mauretania. The most important modification in the new 

 irules is in the basis for determining the " transverse 

 number" and the "longitudinal number." The former 

 number is now to be found by adding the breadth and 

 ■depth only, and the latter by multiplying the length by 

 the sum of the breadth and depth. It is also of import- 

 ance to notice that all the sections in the tables conform 

 to the standards of the Engineering Standards Committee. 

 This is a very wise move, and is much to be conunended. 

 Another step in the right direction has been taken in the 

 adoption of a unit for scantlings of one-fiftieth of an inch 

 instead of one-twentieth as in the old rules. This not 

 only conforms with the decimal system, but, as 0-02 inch 

 is practically half a millimetre, a close connection with 

 the metrical system is secured. As Lloyd's Register covers 

 between 70 per cent, and 80 per cent, of the world's 

 shipping for insurance purposes, the new rules cannot fail 

 to influence the shipbuilding and steel industries in this 

 and most foreign countries. 



A NOTE in the Bulletin de I'lnsHtut Pasteur for May 30 

 (vii., No. 10, p. 453) announces the discovery by Carlos 

 Chagas, of Rio de Janeiro, of a new human trypanosome 

 parasite (T. cruzi), conveyed by a bug (Conorrhinus), and 

 causing an often fatal illness among miners and others 

 in the State of Minas. 



The Bulletin of the Johns Hopkins Hospital for June 

 (xx.. No. 219) contains an interesting historical essay, by 

 Dr. Gerster, on the life and times of Gerhardt van 

 Swieten, physician to the Empress Maria Theresa, who 

 was born in Leyden in 1700 and died in 1772 at Schon- 

 brunn. 



A COMPREHENSIVE note on the cartography of the 

 Philippine Islands is given by Prof. Guido Cora in Bollet- 

 iino delta Soc. Geogr. Ital. as a notice of the recent map 

 ■of the islands compiled from original sources by Mr. C. W. 

 Hodgson. 



We have received from the Nottingham Free Public 

 Library a copy of a simply arranged supplementary science 

 •catalogue of the central lending library dealing with books 

 in most branches of science published between 1901 and 

 the present year. 



Mr. R. B. Henderson, assistant master at Rugby 

 •School, has written an introduction to the study of moths 

 and butterflies for the Rugby School Natural History 

 Societv, entitled " The Scaly-winged." It will be published 

 "immediately by Messrs. Christophers. 



We have received vol. vi. of " Contributions from the 

 Jefferson Physical Laboratory." It consists of a reprint of 

 twelve papers which have appeared in the Proceedings of 

 the American Academy of Science or in other periodicals 

 •during the past twelve months. Five of these papers have 

 already been noticed in these columns. 



In the announcement in Nature of May 27 (p. 375) of 

 the resignation by Mr. H. H. Clayton of his position at 

 the Blue Hill Meteorological Observatory, it was stated 

 that he had been in charge of the observatory since 1894. 

 This statement does not express the position exactly. Mr. 

 Clayton has served for many years as observer or meteor- 

 ologist, and his researches have added to the reputation 

 •of the observatory, but the director is Prof. Lawrence 

 Rotch, who founded the observatory in 1S85, and provides 

 for its material support. 



NO. 2071, VOL. 81] 



The June number of the Stonyhurst Magazine contains 

 an illustrated description of the Milne seismograph used 

 in the National Antarctic Expedition in H.M.S. Discovery 

 under Captain R. F. Scott, R.N., in 1904. The seismo- 

 graph is now a permanent loan to the observatory at 

 Stonyhurst from the Antarctic committee of the Royal 

 Geographical Society. The instrument stands at Stony- 

 hurst on a solid stone pillar fixed in 12 inches of concrete ; 

 its position is lat. 53° 50' 40" N. and long. gm. 52.68s. W. 

 of Greenwich. A new recording apparatus has been 

 secured, and there is every reason to hope that useful 

 observations will be made at the new station. 



OUR ASTRONOMICAL COLUMN. 



Comet 1909a, Borrellv-Daniel. — Further observations 

 of comet 1909a have revealed no striking features either in 

 its form or in its behaviour. In No. 4334 of the Astro- 

 nomische Nachrichten M. Chofardet records the observa- 

 tions made at the Besan(;on Observatory, and states that 

 on June 17 and 19 the comet was of magnitude no or 

 12-0, had a round, diffused head of i^5' diameter, and a 

 vague condensation which could be seen occasionally by 

 oblique vision. 



A New Form of Comparison Prism. — In all spectro- 

 scopic work where a comparison prism placed over the slit 

 is used, the dark band between the compared spectra, pro- 

 duced by the edge of the prism, constitutes an inconvenience 

 which may prove a source of error. To remedy this defect, 

 Prof. Louis Bell has employed a specially designed com- 

 pound prism, in which the light from one of the sources 

 is reflected from the fine edge of a thin layer of silver, 

 whilst that from the other source is allowed just to miss 

 the edge. Thus the line of demarcation is practically 

 eliminated. The method of preparing such compound 

 prisms is described, and illustrated by diagrams, in No. 4, 

 vol. xxix., of the Astro physical Journal (p. 305). 



Halley's Comet. — No. 4330 of the Astronomiscke 



Nachrichten contains two search-ephemerides for Halley's 

 comet. The first is by Dr. Holetschek, who discusses the 

 probable date of perihelion and gives three ephemerides, 

 one for May 16-45, i9io> 3"d the others for thirty days 

 before and after respectively. At the previous apparition, 

 in 1S35, the comet was discovered 102 days before the 

 perihelion passage, when its distances from the sun and 

 earth were 19 and 2-4 astronomical units respectively; the 

 corresponding distance from the sun will occur, according 

 to Dr. Holetschek's data (T = May 16^45, 1910), on 

 February 3, 1910. The second ephemeris has been com- 

 puted by Herr L. Matkievvitsch from the data given in 

 the essay which won the Astronomische Gesellschaft prize ; 

 the positions now given vary considerably, at different 

 epochs, from those previously referred to in these columns 

 (Nature, No. 2046, January 14, p. 320). 



The Polarisation of the Solar Corona. — In the June 

 number of the Bulletin de la Societe astronomique de 

 France M. Salet discusses at length the photographs 

 obtained at the 1905 eclipse with a polariscopic camera. 

 These photographs show the coronal radiations to be 

 strongly polarised right down to the moon's edge, thereby 

 indicating that reflected light is being dealt with ; but the 

 spectroscopic observations indicate that radiations directly 

 from a light-source are in question. M. Salet suggests 

 that the apparent contradiction may be explained by the 

 theory that the bright radiations observed spectroscopically 

 are due to metallic vapours rendered fluorescent by the 

 intense solar radiation. In this condition metallic vapours 

 give band spectra, and the superposition of these might, if 

 small dispersion were employed, produce the appearance of 

 a continuous spectrum such as has been observed. In 

 support of his theory M. Salet quotes the observation of 

 Sir Norman Loclcyer at the eclipse of 1SS2, that the coronal 

 spectrum appeared to be formed of superposed bands, and 

 directs attention to the discovery of magnetic fields by 

 Prof. Hale, which, with a rotating sun, afford the con- 

 ditions necessary for his theory. 



