546 



NATURE 



[January 13, 19 16 



and S. ; it is absent, however, from the leaves of the 

 latter. The glucoside and its enzyme in IF. tinctoria 

 are distinct from those of Indigofera arrecta and I. 

 sumatrana, although the Wrightia enzyme has some 

 action on the glucoside of Indigofera, and vice versd. 

 The question of the conditions leading to the formation 

 of indican in plants is discussed at some length. 

 Indican is produced in the dark by etiolated shoots of 

 /. arrecta, and there is no variation in indican content 

 between night and day in /. arrecta and I. sumatrana. 

 Moreover, no marked effect is produced by keeping 

 plants of I. sumatrana in the dark for thirty-six hours. 

 In the light of present knowledge no definite function 

 can be assigned to the indigo-yielding glucosides in 

 general or to the glucoside of any special species. 



The last quarterly Bulletin of the Seismological 

 Society of America (vol. v., 1915, pp. 12 1-9) contains 

 the presidential address delivered by Mr. A. McAdie 

 on August 4. The writer notes that the last catalogue 

 of earthquakes issued by the International Seismo- 

 logical Association was that for the year 1907, pub- 

 lished five years later, and he suggests that the cata- 

 logues for subsequent years might be issued under 

 American auspices, possibly with the aid of the Seismo- 

 logical Society. The material for such' catalogues is 

 now in German hands, and it is worthy of notice that 

 Mr. Otto Klotz, of Ottawa, has been compelled to 

 suspend his annual lists of epicentres owing to the 

 lack of reports from Europe since the outbreak of the 

 war. Moreover, urgent as are the claims of the war 

 upon us, the Seismological Committee of the British 

 Association has not ceased its useful task of collecting 

 and analysing the records from British and Colonial 

 observatories, and no other country in the world is 

 connected with earthquake stations so numerous and 

 so widely scattered over the globe. 



The Weather Bureau of the U.S. Department of 

 -Agriculture has reprinted a " Note on the Effects of 

 Raingauge Exposures," by Mr. W. G. Reed, from the 

 Monthly Weather Review for July, 1915. For two 

 years the University of California has been engaged 

 in an extensive study of the rainfall conditions over 

 the watershed of Strawberry Creek, which has an 

 area of about one square mile. During 1913-14 rain- 

 fall measurements were made from five standard 8-In. 

 gauges, visited at the end of each storm, and in the 

 autumn of 1914 the number of gauges was increased 

 to thirteen. The gauges are at different heights above 

 sea-level, ranging from 520 to 1655 ft., and the heights 

 above ground range from 8 to 22 in. It is stated that 

 from a strictly meteorological point of view the most 

 important result so far seems to be the difficulty, if 

 not the impossibility, of determining the precipitation 

 on a watershed hy means of ordinary gauges where the 

 area is broken into valleys and ridges. It was hoped 

 to make experiments with shielded gauges, but this 

 was not carried out. It is noted that the catch of the 

 gauge is largely controlled by local conditions, and 

 perhaps the desire or attempt to shield the gauge 

 from wind has too much attention. Precise details 

 are given as to the exposure of the several gauges 

 and the results, and ratios of the individual gauges 

 to the average are given. The discussion has been 

 NO. 241 I, VOL. 96] 



carried out with great care and affords an exceed- 

 ingly interesting inquiry. 



The "James Forrest" lecture before the Institution 

 of Civil Engineers this year took the form of a detailed 

 critical paper on electric railways, by Mr. H. M. 

 Hobart, and in the absence of the author, in America, 

 was read by Mr. John A. F. Aspinall. Mr. Hobart 

 described in detail the working of the Butte, Anaconda, 

 and Pacific 2400-volt direct-current railway, and other 

 American lines, and gave exhaustive figures to show 

 the gain in economy since the steam locomotives Tiave 

 been replaced by electric locomotives. Comparing the 

 single-phase and high-pressure D.C. systems, he 

 argued that even with sparse traffic the latter was the 

 most economical. His general conclusions were that 

 we are on the eve of the extensive employment of 

 electric locomotives on railways at present run by 

 steam, thai the D.C. system is the most appropriate, 

 and that D.C. locomotives for use from high-pressure 

 contact conductors are now a thoroughly demonstrated 

 success. 



The British Journal of Photography for December 

 24, 1915, contains the first part of Mr. F. J. Cheshire's 

 lecture before the Royal Photographic Society on the 

 modern range-finder. With the help of a diagram 

 involving two similar triangles the geometry of range- 

 finding is very clearly explained, and it is shown that 

 the error in the measured range due to a constant 

 small error in the determination of the displacement of 

 one image with respect to the other is proportional 

 to the square of the range. Mr. Cheshire starts with 

 a simple range-finder consisting of two photographic 

 cameras firmly attached to the ends of a rod a yard 

 long, so that their lenses are in the same plane. He 

 shows how by first pointing the instrument at a star 

 and marking the positions of the images on the 

 ground glass' plates in the focal planes, then getting 

 the image of a near object on the star mark in the left- 

 hand camera, and measuring the distance of the image 

 from the star mark in the right camera, the distance 

 of the object from the cameras can be found. From 

 this simple instrument it is shown how the range- 

 finders of Clark (1858), Adie (i860), Mallock (1885), 

 Christie (1886), Barr and Stroud (1888), and Marindin- 

 (1901) may be considered to have developed. 



For many years past the custom of delivering- 

 lectures before the Chemical Society at its ordinary 

 scientific meetings has practically lapsed, although an 

 important series of memorial lectures has been main- 

 tained. Possibly as a result of the diminished flow of 

 miscellaneous researches caused by the prolongation 

 of the war, the custom has now been revived. The 

 first lecture of the series, on "The Principles of Crop 

 Production," was delivered by Dr. E. J. Russell, of 

 Rothamsted, on November 18, 19 15, and is reproduced 

 in full in the Society's Journal for December, 1915. The 

 lecture is illustrated with a striking series of diagrams, 

 as well as by actual photographs showing the effect 

 on the growth of the plant of various quantities of 

 manures. Further lectures will be given by Prof. 

 Bragg and by Mr. F. Gowland Hopkins. 



A NEW form of viscometer is described by Mr. W. R. 

 Bousfield, K.C., in the recent December issue of the 



