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NOTICES OF NEW BOOKS. 



Report of the Inquiry Committee on the Standardisation of the 

 Elements of Optical Instruments. London : Published for the 

 Department of Scientitic and Industrial Research bv His 

 Majesty's Office. 1920. Price l.s. net. 



The question of standardisation of the elements of optical instruments, 

 the need for which was made evident by experience during the war, v/as 

 first brought to the attention of the Sub-Committee on Standardisation 

 of the Elements of Optical Design of the Standing Committee on Glass 

 and Optical Instruments by members representing the Ministry of 

 Munitions, the War Office and the Admiralty. Previous to the appoint- 

 ment of the Committee on Standardisation, a questionnaire was addressed 

 to the principal manufacturers of optical instruments, twenty-three in 

 number, in order to ascertain their opinions on the subject generally, 

 and on the following subjects in particular : — Units of measurement ; 

 diameters, focal lengths and radii of curvature of lenses ; small screws ; 

 screw threads for cells and tubing; diameters of tu])es, rods and wire ; 

 thicknesses of sheet metal ; shafts and holes : racks and pinions. 



The replies of the manufacturers indicated great diversity of practice, 

 and showed generally that standardisation would be welcomed by them. 

 The chief objects of the Committee have been to reduce to a reasonable 

 minimum the existing great variety of sizes of some of the components 

 of optical instruments, and to appoint limiting dimensions so as to 

 secure, among components of the same nominal size, real interchange- 

 ability and reasonable closeness of fit. The present Report is confined 

 to certain subjects selected by the representatives of the xidmiralty. War 

 Office and Air Ministry as being most urgent in connexion with the re- 

 designing of Service instruments in the light of experience during the 

 war, but it is applicable to other optical instruments. J. E. B. 



The Microscope : An Introduction to Microscopic Methods and to 

 Histology. By Simon Henry Gage. 1920. x + 474 pp. l^th 

 edition. Published by the Comstock Publishing Co., Ithaca. 

 New York. 



The Growth and Shedding of the Antler of the Deer. By Wilham 

 Maceweu, F.R.S. 1920. xviii + 110 pp. Published by 

 Maclehose, Jackson and Co., Glasgow. Price 10s. 6d. net. 



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