April 5, 1900] 



NATURE 



541 



New Mode of Using the Concave Diffraction Grating. 

 I (JREATI.Y regret that in a note of mine on a " new mode 

 |.of using the concave diffraction grating," in the " Astronomical 

 (Column " of March 22 (p. 501 ), I wrongly interpreted a sentence 

 of Prof Rizzo's article, which led me to think it was inconvenient 

 for him to use the instrument in the usual way. The words 

 " Dr Rizzo investigated this disposition on account of being 

 unable to use the instrument as usually set up," should therefore 

 not have been included The Writeh of the Note 



Internal Stresses in Iron and Steel. 



Can you kindly inform me where I may obtain a copy of the 

 researches of General Kalakoutsky on the "Internal Stresses 

 in Cast Iron and Steel," translated by the late Sir William 

 Anderson, F. R.S., Director-General, Royal Ordnance Fac- 

 tories. Thos. Andrews. 



Sheffield, March 27. 



The work in question — " Investigations into the Internal 

 Stresses in Cast Iron and Steel," by General Nicholas Kala- 

 koutsky — was published by Georee Reveirs, 4 and 5 Graystoke 

 Place, Fetter Lane, E.G., in 1888. 



Second-hand copies can occasionally be procured from dealers 

 in technical books. B. H. B. 



ELECTRICITY IN WAR. 

 T T NDER the Presidency of the late Dr. Hopkinson, 

 ^ the Institution of Electrical Engineers established 

 an Electrical Engineer Volunteer Corps affiliated to the 

 Royal Engineers. Lord Kelvin is now its Honorary 



in warfare, and in consequei^qe of their unfamiliarity 

 with existing apparatus are very likely to quickly notice 

 methods of improving it. 



Hitherto many of these men have had a yearly drill in 

 the management of the electrical apparatus in use for 

 submarine mining and home defence. 



I would point out that the ordinary volunteer drill of 

 these men is only a part of their preparation for the 

 nervous tension of an enemy's presence. There is no 

 more trying experience than that of a young engineer in 

 a central electric light station when the "peak" of the 

 evening load is coining on, and every appliance is worked 

 to its highest capacity ; when the stoker cannot get 

 enough draught for his boilers, and a short-circuit sud- 

 denly takes place. It is interesting to note how the man 

 who was nervously afraid of himself beforehand, braces 

 himself up to meet the emergency, and to his own wonder 

 afterwards, manages to do exactly the right thmg at the 

 critical moment. A man who has proved his coolness in 

 this sort of way is not likely to be flurried in the field, even 

 when a rain of those most dangerous of all missiles, the 

 y] mm. Vickers-Maxim shells, are exploding about his 

 search-light. 



.A few years ago, when Major Crompton vainly urged 

 the necessity for the provision of new apparatus, practice 

 in the use of existing field search-lights, &c., such as 

 might lead to better designs, and money to enable such 

 better apparatus to be constructed and tested, some of 

 us felt very strongly that the War Office was wasting an 

 invaluable opportunity. 



A committee of the Institution of Electrical Engineers 

 was able to assure Major Crompton of considerable 



I'lu. I. — Tr.-iclion eiigi 



Colonel ; the well-known electrical and mechanical 

 engineer, Mr. R. E. Crompton (formerly Captain in 

 the Rifle Brigade) is its Major. It is a corps consisting 

 of 350 young men, most of whom have had a scientific 

 education ; they are all engaged every day in practical 

 electrical engineering work ; many of them are con- 

 stantly engaged in inventing new apparatus and im- 

 proving old apparatus ; all of them are athletic, and 

 enjoy such exercise as the volunteer drill affords ; 

 iTiany of them are experienced bicyclists ; all of them 

 are curious as to the existing applications of electricity 



NO. 1588, VOL. 61] 



pecuniary help in case the War Office gave facilities.and 

 it was proposed that the corps should take up some one 

 problem at a time, and work it out to a thoroughly good 

 practical result. For example, the production of a really 

 good field search-light was proposed. To work awhile 

 with the existing things, which were like ship search- 

 lights carried upon ordinary waggons, and to expend all 

 the ingenuity of the corps upon the creation of a piece 

 of apparatus perfect for military purposes. This involves 

 also the best design of mobile steam engine and dynamo 

 plant ; the best kind of cable, and the best ways of paying 



