238 



NATURE 



[October 20, 1921 



Letters to the Editor. 



(The Editor does not hold himself responsible for 

 opinions expressed by his correspondents. Neither 

 can he undertake to return, or to correspond with 

 the writers of, rejected manuscripts intended for 

 this or any other part of Nature. No notice is 

 taken of anonymous communications.] 



The Development of Optical Industries. 



We are asked by our principals, Messrs. Carl Zeiss, 

 of Jena, to transmit the following observations on the 

 leading article, "The Promotion of Our Optical In- 

 dustries," which appeared in Nature of February lo 

 last (vol. 106, p. 749), with the request that you would 

 kindly extend to them in your columns the publicity 

 which the importance of the subject deserves. It is 

 regrettable that so long an interval should have been 

 permitted to elapse, but we understand that the head 

 of the department at Jena which deals with Press 

 matters was absent from headquarters for several 

 months : — 



"To the leading article, 'The Promotion of Our 

 Optical Industries,' which appeared in Nature of 

 February lo last, some remarks present themselves 

 which call into question the position assumed by the 

 British Optical Instrument Manufacturers' Association. 

 The article also contains some statements which are 

 erroneous and cail for correction. 



"It would seem that the writer .of this article was 

 not perfectly acquainted with the history of English 

 glass manufacture, for the words ' supremacv in the 

 optical glass industry, which was established in this 

 country as early as 1837,' 'ife scarcelv supported bv 

 an historical investigation. Such a supremacv did not 

 then exist in England. It may perhaps be worth 

 while to furnish some trustworthy historical data. 



"When between 1825 and 1829 experiments on a 

 very large scale were made in England, of which 

 the Bakerian lecture given by Faraday at the 

 end of 1829 was a detailed account, the position 

 of English glass manufacture was not very flourish- 

 ing, nor were the glasses of Benedictbe'urn, near 

 Munich, or those of les Brenets, in Neuchatel, at that 

 time obtainable in England. It would seem that even 

 Faraday's energy was unable materially to alter that 

 state of things, for his " heavy glasses ' were never 

 largely employed for optical instruments in general. 

 G. Bontemps's opinion that Faraday's experiments 

 were discontinued, because later on ordinary optical 

 glass was obtainable in France and in Switzer- 

 land, may possibly be correct. W. V. Harcourt's 

 earlv experiments between 1834 and 1844 ^""^ very 

 imperfectly known, but the result at that time was 

 scarcely of any practical importance. G. G. Stokes, 

 in any case, did not think much of the first specimens 

 Harcourt sent in during 1862, and he attributed — 

 very justly, one may think — a great part of the later 

 remarkable scientific achievements (themselves without 

 great practical value) to their united endeavours 

 between 1862 and 1871. But these are matters of a 

 much later period ; we may, however, turn to the 

 testimony of an English eyewitness of 1849, the tele- 

 scope manufacturer, W. Simms, on the former state 

 of English flint-glass manufacture. From his descrip- 

 tion we cannot infer anything of that English 

 ' supremacy as earlv as 1837,' but must conclude that 

 in England flint-glass for optical purposes had not 

 been made commercially before the necessarv technical 

 knowledge was imported from France, when G. Bon- 

 temps came over to Chance's factory after 1848. After 

 that time ordinary crown glass and ordinary flint- 

 glass of good quality were put on the market in 



NO. 2712, VOL. 108] 



France, in Switzerland (by Th. Daguet in Solothurn 

 up to the time of his death in 1870), and in England, 

 the Munich factory working only for its proprietor, 

 the optician Merz. 



" This state of things was difficult to alter, as these few 

 factories in thus practically monopolising the glass trade 

 had no interest in making costly experiments for new 

 kinds of glass for which no ready sale could be war- 

 ranted. It was left to the man of science who 

 demanded glasses with new properties to carry 

 out the melting, and Abbe's and Schott's history 

 shows how difficult it was to make the necessary 

 scientific investigations. In order to facilitate in- 

 dustrial manufacture, the Prussian Government in 

 1883 contributed, the sum of 60000 marks (3000Z.), 

 whereas, according to Payen, the cost of Faradav's 

 experiments had been 150,000 francs, equivalent to 

 6000L, or even more if regard be paid to the then 

 (1830) higher purchasing power of money. Apart 

 from that sunt of 3000L no State subsidy has ever 

 been paid to the Jena glass factory, nor was there 

 any necessity for any further subsidy, for even the 

 optical branch of the Jena glass factory of Schott 

 und Gen. was financially successful. The idea that 

 the manufacture of optical glass is impossible on a 

 commercial basis finds further refutation in the fact 

 that in 1893-94 Ch. E. Mantois, of Paris, began to 

 melt the new kinds of glass for commercial purposes, 

 and that a new German optical glass factor}-, Send- 

 linger optische Glaswerke G.m.b.H., was founded 

 in 1913. 



" Summing up the results, it is clear that English 

 men of science of the highest standing were at work, 

 and at least one of them — Faraday— ^was liberally 

 assisted by the Government. That the success 

 achieved did not come up to expectations may be attri- 

 buted to the lack of a close and efficient co-operation 

 such as existed between Abbe and Schott, which 

 cannot be guaranteed by the cleverest institution. 



"Another point in the article may well be ques- 

 tioned : 'If the British optical instrument industrv is 

 to be maintained and to develop so as to turn out 

 products equal at least to the best products of other 

 nations, it must not be dependent on foreign sources 

 for the supply of optical glass, but must have an 

 adequate home supply, equal, again, at least to the 

 best available anywhere.' 



" History does not point to the existence of such 

 a very close relation between the welfare of the glass 

 founder and of the optical instrument maker in the 

 same country. Let us take, for instance, the history 

 of 'the photographic objective, and this because we 

 have here a modern instrument the history of which 

 is sufficiently well known. The earliest (1840) inven- 

 tion of the first order belongs to Petzval, a mathe- 

 matician in Vienna, who had to use French glass ; 

 a second invention, though devoid of commercial 

 success (1843), belongs to the American engineer, 

 A. S. Wolcott, who likewise had only Fi-ench glass at 

 his disposal. He was the first to publish a remarkable 

 theory of the symmetrical lens, but it cannot be said 

 that his discovery would have been improved by his 

 having at his disposal raw material from an American 

 factory. A. Steinheil bringing out his different series 

 of apianats and antiplanats between 1866 and 1881 

 may well be cited as an optician who was especially 

 successful in his use of readily procurable foreign 

 (French and English) glass. And when, finally, we 

 arrive at the period of Jena glasses, we may point out 

 that, apart from Zeiss 's assistants, scientific men of 

 no connection with Schott's factory, like E. von 

 Hoegh, A. Kerber, R. Steinheil, D. Kaempfer, etc., 

 had to take the glasses from Schott as offered. 



