October 20, 192 1] 



NATURE 



239 



Amongst these a very important place must be re- 

 served for H. Dennis Taylor, who constructed the ven,- 

 simple and very efficient typje of the triplet, ' the 

 Cooke lens,' or better ' lenses,' of the foreign material 

 willingly placed at his disposal. 



■■ Great opticians like Fraunhofer and Abbe were 

 undoubtedly wanted in order to show to the in- 

 credulous optical world the necessity for new glasses 

 by means of which difTerent optical instruments could 

 be brought to much higher efficiency ; this feat having 

 once been accomplished, the interest of the manu- 

 facturing optician and the glass founder are not nearly 

 so closely connected as the writer of the article would 

 appear to believe. We call to mind two characteristic 

 instances where a founder, by pushing his own advan- 

 tage too far, materially damaged the optician. In 

 Munich, as was mentioned earlier, the optician Merz 

 was proprietor also of the glassworks ; his short- 

 sighted exclusion of competitive opticians from the 

 output of this factonk- was the real cause of the death 

 from inanition of the oldest glass factory founded bv 

 Guinahd and improved by Fraunhofer. On the other 

 hand, the practical monopolisation of the glass market 

 by French and English houses between 1848 and 1883 

 was certainly convenient from the founder's point of 

 view, but it materially hampered the progress of the 

 optical engineer. In 'the long run this shortsighted 

 policy could not, however, prevent the establishing of 

 more progressive glass manufactories, and this com- 

 petition was undoubtedlv in the interest of the optical 

 manufacturer, although the old factories, showing less 

 scientific initiative, suffered bv it. The German 

 optician certainly profited by this competition, but he 

 did so in common with the' foreign optician, whether 

 American, Austrian, English, French, Italian, or 

 S"wiss. 



•We do not hesitate to state that optical mathe- 

 maticians of all countries will hail with strong 

 approval every extension of the choice of glasses at 

 their disposial, and deplore their exclusion— be the 

 reason whatever it may— from anv valuable material 

 available to opticians in foreign countries." 



J. \A'. Atha and Co. 

 „ „ , (A. F. Degenhardt.) 



8 Southampton Row, London, W.C.i, 

 August 4. 



The observations of Messrs. Carl Zeiss, of Jena, 

 challenge the article, '■ The Promotion of Our Optical 

 Industries," published in Nature of Februarv 10 last 

 on three points :—(i) They denv what the article 

 asserted, that supremacy in the optical glass industrv 

 passed over from this countrv to Germanv, on the 

 grounds that England never held supremacv in this 

 industry. (2) They denv that State subsidies were 

 made continuously to t'he optical glass industrv in 

 Germany from the time of the investigations of Schott 

 and Abbe m 1881 down to the declaration of war in 

 1914; and they state categoricallv that, apart from 

 a sum of 3000Z. contributed bv the Prussian Govern- 

 ment in 1883, no State subsidv has ever been paid to 

 the Jena glass factory. (3) Thev dispute the proposi- 

 tion that 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 production 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." 



(i) As to the first point, the '• trustworthv historical 



data supplied by Messrs. Carl Zeiss are 'incomplete 



and inconclusive. The article in Nature did not 



assert that "supremacy" was established as early as 



NO. 2712, VOL. 108] 



1837, t)"*^ \.\\2it the optical glass industry was estab- 

 lished in this country in that year. The supremacy 

 came later. It was not until 1848, when Bontemps 

 left Choisv and came to Messrs. Chance's works, thai 

 Messrs. Chance Brothers were able to surmount the 

 difficulties which surrounded the manufacture of 

 optical glass. Such progress was afterwards raadt- 

 with the production of large meltings of uniform 

 optical glass that the English firm quickly gained a 

 very high reputation for the manufacture of large 

 discs of optical glass of the finest quality for astro- 

 nomical work. A few instances may be mentioned 

 of their successful production of large telescope discs, 

 that most severe test of the skill of the optical glass 

 manufacturer. 



At the Great Exhibition of 185 1 the firm showed a 

 20-in. disc of light flint " for daguerreot\-p© apparatus " 

 and a 29-in. disc of dense flint, weighing 200 lb., for 

 which a Council medal was awarded. In 1855 a corn- 

 panion crown disc was shown in Paris, and this 

 Foucault pronounced to be the finest piece of glass 

 he had ever seen. Discs of 24 in. and 29 in. were 

 produced in 1856, and a pair of i8-in. discs sold to 

 Messrs. Alvan Clark and Sons in i860 resulted, during 

 the testing of the object-glass made from them, in the 

 discovery of the companion to Sirius. A pair of 26-in. 

 discs, produced in 1862, were worked by Messrs. Cooke 

 and Son, York, for Mr. R. S. Newall, into the largest 

 refractor then in existence, and this was later given 

 to Cambridge L'niversitv. In 1871 and 1874 Messrs. 

 Clark worked pairs of 26i-in. discs, the former being 

 used for the Washington refractor, with which the 

 satellites of Mars were discovered. The 28-in. objec- 

 tive for Greenwich was finished by Sir Howard Grubb 

 in 1887. . 



The question of the alleged supremacy of a particular 

 country in anv chosen industrv- may always be difficult 

 of proof and largelv a matter of opinion, but there is 

 nothing in Messrs.' Zeiss 's detached historical data to 

 invalidate, and much in the few facts we have just 

 given to substantiate, the view that for some consider- 

 able period between 1848 and 1880 England held 

 supremacv in the manufacture of optical glass. For a 

 number of vears from about 1880, during which period 

 the discs for the great Lick and Yerkes telescopes 

 were manufactured, Britain took a place second to 

 that of France. It is significant that later in their 

 letter Messrs. Zeiss speak of "the practical mono- 

 polisation of the glass market by French and English 

 houses between 1848 and 1883." 



(2) On the question of the subsidy the statement 

 of Messrs. Zeiss must be accepted as authoritative, 

 and we notice that it is limited to a State subsidy. 



(3) But it is on the third point that issue can be 

 directly joined with Messrs. Zeiss 's arguments, which 

 seem to suggest that the development of a national 

 optical instrument industry is in no way dependent 

 on, and would not be hampered by the absence of, 

 an adequate home supply of optical glass. The in- 

 stances thev quote of advances in optical design and 

 improvement in optical instruments prove nothing 

 more than that dependence on a foreign supply for 

 optical glass has not in the past entirely prevented 

 some enterprising opticians and mathematicians from 

 making distinct advances in optical design. But this 

 is a far cry from establishing the proposition that a 

 healthv and vigorous optical instrument industry has 

 ever been, or can be, established in any country 

 dependent entirely on foreign sources for its supply 

 of optical glass. It is true that the British optical 

 instrument industry has gained much since 188 1 from 

 its access to the products of Jena, but who shall 

 estimate how much it has lost through the compara- 



