May 17, 1917] 



NATURE 



being much better on this area than on the rest of the 

 fieW. It is pointed out in conclusion that many points 

 still remain to t>e investigated before the use of the 

 overhead electric discharge can be definitely recom- 

 mended as a sound extension of agricultural practice. 



The growing importance of magnesite as a refrac- 

 tory material and for use in magnesian cement has led 

 to its exploitation at the mining township of Bulong, 

 in the N.E. Coolgardie Goldfield of Western Australia 

 (F. R. Feldtmann, in Ann. Report Geol. Surv. of W. 

 ^ Australia for 1915). The material requires picking 

 from the serpentine in which it occurs, but veins up 

 to 2 ft. in thickness have been traced. In this, as in 

 other instances, the magnesite is held to have been 

 formed by waters containing carbon dioxide per- 

 meating a decomposing igneous complex of basic 

 character. 



We have received from Mr, David Currie a letter 

 relating to the article on " Empire Development and 

 Organisation " which appeared in our issue of April 

 26. He directs attention to the fact that, although 

 Canada is by far the largest producer of raw asbestos, 

 Russia mines a substantial amount of this mineral, 

 and Rhodesia is being developed as an important field. 

 He regards the statement that the United Kingdom 

 is largely dependent on outside sources, especially the 

 United States, for its manufactured asbestos as in- 

 correct, affirming that the imports from the States 

 are " insignificant and even less than our exports to 

 the States, in spitg of the prohibitive tariff." The 

 authority for the statement challenged by Mr. Currie 

 is contained in paragraph 336 of the Blue Book 

 Cd, 8462. Moreover, in the appendix (p. 172) the 

 Commissioners state : — " It is to be noted that the 

 United Kingdom, although possessing the most up- 

 to-date plants and methods, is largely dependent on 

 foreign sources for the manufactured asbestos it uses. 

 In 19 13 the net imports of asbestos manufactures were 

 valued at 232,000/., while the exports of asbestos 

 manufactured in the United Kingdom (excluding 

 engine packing) were valued at 105,000/. Quantities 

 and countries of origin are not recorded." 



The Revue generale des Sciences for March 15 con- 

 tains a clearly written and readable article on tele- 

 meters by Prof. H. Pariselle, of the French Naval 

 School. It explains the principles on which tele- 

 meters act and describes the best-known instruments 

 of each type. For infantry fire a simple and robust 

 instrument is necessary, and no high degree of 

 accuracy can be expected. A triangular slit in a small 

 sheet of metal, held at arm's length and moved until a 

 soldier seen at a distance fills the interval between the 

 top and bottom edges of the slit, is a popular form 

 of instrument, and is fairly accurate at small dis- 

 tances. For greater distances some form of double- 

 image field glass or telescope has been much used. 

 The two images of a soldier may be arranged to fall 

 in the same vertical line, and the point on the upper 

 image, at which the top of the head of the lower 

 appears, may be noted, and the distance determined 

 from its position. For the use of the artillery much 

 more accurate instruments -are necessary, and some 

 form of double-image instrument, using a short base 

 from the ends of which the two views of the object 

 are taken, has come mto universal use. The Barr 

 and Stroud instruments use bases from 80 cm. to 

 274 cm., the shorter in field work and the longer in 

 the Navy. Recently the Lawford-Copper instrument, 

 on similar lines to the Barr and Stroud, but with a 

 variable base, has been introduced. 



NO. 2481, VOL. 99] 



Writing in the Scientific American for April 21, Mr, 

 EUwood Kendrick deals with recent chemical develop- 

 ments in America. He points out that in treating 

 metals the manufacturer has gone ahead by leaps and 

 bounds, the reason being that, beginning with -Andrew 

 Carnegie and the Pittsburgh ironmasters, the chemist 

 has been called in. He has also been welcomed in 

 the f>etroleum indus^y, in the making of explosives, 

 and latterly in the manufacture of coal-tar and other 

 products. In other fields the chemist has not been 

 wanted; the dread of the theorist has kept the doors 

 of certain industries closed to him, with consequent 

 waste and loss. After reference to the growing use 

 of ferments and bacteria in chemical industry, Mr. 

 Kendrick deals with a recent article on nitro-starch 

 as an explosive. The difficulties with this nitro- 

 product have been, in the first place, lack of stability 

 when made by any practical method, and, secondly, 

 difficulties in nitration owing to clotting, etc. It is 

 claimed that the problem of producing a permanent 

 nitro-starch has now been -solved. By working up So 

 to 85 per cent, with nitroglycerine a suitable explosive 

 is obtained, and comparison is made between it and 

 dynamite. Nitro-starch is claimed to.be the cheapest 

 of all hieh explosives. With present food problems, 

 however, it can have no immediate interest for Eul-ope. 

 It is also stated tliat a licence has been granted in 

 Switzerland for the manufacture of alcohol, primarily 

 for industrial purposes, from calcium carbide. The 

 works will be built at' Visp. 



The annual general meeting of the Society of 

 Chemical Industry is provisionally fixed to be held at 

 the University of Birmingham on July 18-20. 

 The following papers are promised : — "Chemical 

 Porcelain," H. Watkins; " Duro-Glass," Dr. M. W. 

 Travers; "British Sources of Sand for Glass and 

 Metallurgical Work," Dr. P. G. H. Bosv.ell ; ' Refractory 

 Materials," W. C. Hancock; " Synthetic Nitrates," 

 E. K. Scott; "Nitrates from the Air," Dr. Maxted; 

 "Low-temperature Distillation Fuel," Prof. O'Shea; 

 "Industrial Fuel from Gas Works," E. W. Smith; 

 "Calorific Value of Industrial Gaseous Fuel," W. j! 

 Pickering; "High-pressure Gas for Industrial Purl 

 poses," Mr. Walter; "Some Sources of Benzol and 

 Toluol for High Explosives," T. F. E. Rhead; "Arti- 

 ficial Silk," L. P. Wilson; "Activated Sludge Pro- 

 cess," E. Ardern; "Organisation of Industrial Re- 

 search," H. W. Rowell; "Scheme for Co-operative 

 Industrial Research," H. W. Rowell- "Vulcanisation 

 of Rubber," Dr. D. F. Twiss. 



OUR ASTRONOMICAL COLUMN. 

 Comet 1917a (Mellish).— The following revised 

 ephemeris for this comet, based upon a new orbit 

 calculated from observations made on March 21, April 

 4, and April 20, has been received • from Copen- 

 hagen : — 



1917 RA. Decl. Log A Mag 



h. m. s. , , 



May 27 I 56 28 -12 562 02236 7-2 



June 4 2 .7 28 14 11.5 02419 7.5 



I- ^6 53 15 31-8 0-2559 7-8 



20 24 45 16 59-8 02666 8-0 



, , -?. 31 5 18 37-3 0-2748 8-2 



July 6 35 46 20 25-6 0-2810 8-4 



14 38 46 22 242 0-2859 8-6 



22 - 2 39 54 -24 33- 1 0-2901 8-7 



The comet is now too far south for observatic«i in 

 Europe. It was apparently this comet which was 

 obser\-ed in Australia on April 19, and described as 

 a new comet (see Nature, April 26, p. 172). 



