44S 



NATURE 



[August 2, 191 7 



bhinjua, to be mixed afterwards with fresh chhilua. 

 The rmniah seldom or never attempts to separate 

 the mixed sahs, as this is forbidden to him by the 

 Salt Department. The crude product is sold, 

 usually through a middleman, to the refiner, who 

 works under Government supervision. 



The restrictions of the Indian Salt Department, 

 according to Mr. Hutchinson, undoubtedly hamper 

 the operations of the nuniah, who has no induce- 

 ment to improve his methods so as to turn out a 

 better article. The whole process as at present 

 carried on is essentially wasteful and uneconomical, 

 and might be greatly improved in the absence of 

 official interference. The conditions for the most 

 economical production of saltpetre are well under- 

 stood by the miniah, and it is to be regretted that 

 he should not be encouraged to make full use of 

 his knowledge and experience. 



The Bulletin is an important contribution to an 

 interesting process of manufacture based primarily 

 upon bacteriological agencies. It forms an ex- 

 cellent example of a purely empirical method 

 which has been elaborated by the accumulated 

 experience of centuries, but the rationale of which 

 has only been made clear by modern biological 

 science. In view of the growing scarcity of 

 nitrates and of their increasing importance in the 

 arts, especially in agriculture, it is to be hoped 

 that the Indian Government will neglect no oppor- 

 tunity of conserving .and extending an industry 

 which is peculiarly well adapted to Indian condi- 

 tions. T. E. Thorpe. 



THE PROMOTION OF TECHNICAL 

 OPTICS. 



'"PHE long-delayed steps which^ — as announced 

 ^ in Nature of May 24 (p. 257) and June 14 

 (p. 317) — have been taken by the Government and 

 the London County Council in concert for estab- 

 lishing the study of optics and of the manufac- 

 ture of optical appliances upon a proper footing 

 in this country, have given great satisfaction to 

 all who are in a position to appreciate the 

 importance of that measure. That the turning 

 of this new leaf should be among the earliest 

 consequences of the war is a fact both of in- 

 trinsic importance and of good augury. The 

 importance of properly organised manufactures 

 of optical glass and of optical instruments has 

 been manifest, and has been pressed upon the 

 Government with great weight of expert 

 authority by the British Science Guild and other 

 bodies for many years past. But in the days 

 before the war, when the optimist was accounted 

 the best as well as the pleasantest of counsellors, 

 it was impossible to secure the attention of our 

 rulers for so modest a proposal as the establish- 

 ment upon an adequate scale of a school of prac- 

 tical optics. 



It is with something more than a sigh of relief 

 that we find ourselves after three years of 

 war able to record this sound decision of the 

 British Government. For, indeed, the matter for 

 congratulation is that there is a British Govern- 

 ment still in a position to act. The thought of 

 NO. 2492, VOL. 99] 



what range-finders m-ean to the British Navy, 

 and of how narrowly we escaped being dependent 

 upon the enemy for our supply of these essential 

 instruments, is almost enough to make one 

 shudder even under the wing of a Royal Navy 

 that has swept the sea. It chanced by the hap- 

 piest of happy accidents that the range-finder 

 which finds the range for our own and all 'the 

 other navies was of British invention, also that the 

 inventor took the trouble to establish its manu- 

 facture in this country as a private enterprise, 

 and, by consequence, that when the war 

 commenced we were in the best possible 

 position to provide both Army and Navy with 

 these important instruments. The Army can, 

 indeed, use alternatives, but the Navy is shut 

 up to the range-finder. Had that been a Ger- 

 man monopoly the battle of Jutland might quite 

 conceivably have been the end of British sea- 

 power. Considerations such as these lead us to 

 place on record the sense of immense relief with 

 which we note the new attitude of the Govern- 

 ment towards one of the things that matter. 



The task before the new department is a large 

 one, and it is beset with many difficulties. That 

 task is chiefly educational, but it is by no means 

 only the education of the student of optics that 

 is here in question. Parliament, and the greater 

 public to which Parliament is responsible, stand 

 in need of education also. The facts just now 

 alluded to concerning the supply of range-finders 

 afford one illustration, and a very striking one, 

 of this necessity. A necessity of a totally dif- 

 ferent kind is exhibited by the conditions govern- 

 ing the supply of optical glass. This, as is 

 perfectly well known, has been for many years 

 past, in large measure, a monopoly of one Jena 

 glass manufacturer. That arrangement was in 

 a certain sense a good and convenient one. The 

 Jena glasses were excellent in quality- — no one 

 could reasonably expect to better them. 

 Specialising in this line, the Jena house was 

 able to produce them in great variety, and did, 

 in fact, list and stock many varieties of optical 

 glass for which the market demand was incon- 

 siderably small. 



Competitive manufacture under these condi- 

 tions could only be wasteful manufacture, and 

 the British glass-makers took what was, from 

 the commercial point of view, the sound position 

 that it was not worth while to spoil a market 

 for a rival which they had no chance of exploiting 

 for their own advantage. Indeed, when it is 

 recognised that the whole world's trade in optical 

 glass would not yield a profit that any successful 

 stockbroker would think considerable, it is easy 

 to understand the reluctance of business men to 

 'embark upon a troublesome business with no 

 better prospect than that of largely destroyin 

 this modest prosperity and then joining in 

 scramble for the residue. 



How, then, are Parliament and the British nation 

 to be made aware of the technical importance of 

 an industry which is commercially of so smal' 

 account? That is one of the problems with 

 which the new department is faced. 



