May 12, 1921] 



NATURE 



325 



interesting accounts of Greenwich Observatory 

 and the long- list of distinguished astronomers to 

 whom British instrument makers owe a large debt ; 

 of the Royal Meteorological Society, which for 

 seventy years has fostered the study of meteor- 

 ology and called forth much skill on the part of 

 the instrument trade; and of the manufacture of 

 optical glass in Great Britain. 



This last chapter contains a somewhat sad story. 

 The method of making optical glass was dis- 

 covered by Guinaud, a Swiss joiner, who lived 

 towards the end of the eighteenth century. It was 

 carried on, but without much success, by Guinaud 

 himself with Fraunhofer at Munich, and by one 

 of his sons working with Bontemps at Choisy-le- 

 Roi, near Paris. In 1848 Bontemps came to 

 England and joined Messrs. Chance at Birming- 

 ham, and for some years the Smethwick firm pro- 

 duced most of the optical glass required by 

 opticians throughout the world. Some forty years 

 ago Schott and Abbe joined forces, and, carrying 

 to success experiments commenced in 1834 by 

 Harcourt and Stokes, w^ere able to offer glasses 

 with properties needed by the optician. The 

 German Government realised what optical glass 

 * meant in time of war, and did its utmost to 

 help the investigators. Then, as now, no support 

 was given by the British Government to 

 the British firm, just as in 1855, when Sir 

 David Brewster did his best to persuade 

 the Government to buy the pair of 20-in. 

 lenses Messrs. Chance had made, "and construct 

 with them the greatest achromatic telescope ever 

 contemplated by the most sanguine astronomer," 

 but could arouse no interest, and until the war 

 the Jena glasses practically held the field. 



The position is somewhat different now. 

 Messrs. Chance and Messrs. Wood, of Derby, 

 make successfully a number of the Jena 

 glasses, and as a consequence of the work 

 carried out in the Research Department three 

 glasses have been manufactured with optical 

 constants rather more extreme than any 

 hitherto available. Still, even now the 

 lesson of the last seven years has not been fully 

 learned, and, in spite of all the promises, a trade 

 vital to the defence of the country seems likely 

 to perish before the Government takes the steps 

 necessary for its support. 



"Great Britain is proud," as the authors of the 

 dictionary claim, "of her predominating share in 

 creating the science underlying the manufacture 

 of optical instruments, ... It is only necessary," 

 they continue, " to mention such names as Newton, 

 Young, Brewster, Herschel, Airy, DoUond, 

 Lister, Maxwell, and Rayleigh to realise to what 

 NO. 2689, VOL. 107] 



a great extent this country has been responsible 

 for the instrument making of the world." The 

 work under review should help, to no small 

 degree, in the realisation of this truth, and the 

 British Optical Instrument Manufacturers' 

 Association is to be congratulated on having 

 brought such a publication to a successful issue. 



Text-books of Organic Chemistry. 



(i) Treatise on General and Industrial Organic 

 Chemistry. By Prof. Ettore Molinari. Trans- 

 lated from the third (enlarged and revised) 

 Italian edition by T. H. Pope. Part i. Pp. 

 XV + 456. (London : J. and A. Churchill, 192 1.) 

 305. net. 



(2) A Text-book of Organic Chemistry. By Prof. 

 A. F. Holleman. Edited by Dr. A. Jamieson 

 Walker, assisted by Dr. O. E. Mott, with 

 the co-operation of the author. Fifth English 

 edition, completely revised. Pp. xviii + 642. 

 (New York : John Wiley and Sons, Inc. ; 

 London: Chapman and Hall, Ltd., 1920.) 

 185. 6d. net. 



THE two books under review are in a sense 

 complementary, the one being mainly tech- 

 nical and the other theoretical. The author of the 

 first says : — 



" Holleman 's treatise is confined to a theoretical 

 and systematic exposition of the many organic 

 compounds, the industrial side of the question 

 and the application of these compounds being 

 almost entirely neglected. It is hence difficult for 

 the student to ascertain which of the thousands of 

 substances described are really of practical 

 importance." 



It would be interesting to have Prof. 

 Holleman 's opinion of Molinari 's treatise. Every- 

 thing depends upon the point of view of the 

 author and upon the class of student for whom he 

 writes. Both books have their good points, and 

 both are deservedly popular. We should, how- 

 ever, be unwilling to put either treatise into the 

 hands of the beginner, who requires something 

 more elementary, more general in scope, and less 

 specialised in treatment. Having obtained a 

 knowledge of fundamental principles, he could 

 then take up Holleman and supplement it with 

 Molinari. No more satisfactory combination 

 could be made; for neither book is complete in 

 itself. 



(i) With all its wealth of detail and illustrations 

 of technical operations, it must be admitted that 

 in Molinari 's treatise the philosophical method is 

 conspicuous by its absence. This is partly due to 



