156 



NA TURE 



[August 4, 1923 



also responsible for an cvi client siiinin;irv of the 

 physics of the human t} 



Several articles on glass [olknv, wriilcn Iroin different 

 points of view by Mr. E. A. Coad-Pryor, Mr. VV. H. 

 Withey, and the late Mr, Harry J. Powell. Mr. J. 

 Rheinberg discourses on graticules and platinised glass ; 

 and the Paterson-Walsh height-finder, which found 

 application in anti-aircraft work in the War, is described 

 by Mr. J. W. T. Walsh. 



Dr. W. W. Coblentz, of the Bureau of Standards, 

 Washington, writes briefly on infra-red transmission 

 and refraction data and includes a number of useful 

 tables. An article on the kinematograph by Dr. J. W. 

 French sets out in interesting fashion the main physical 

 points which have had to be dealt with in bringing the 

 instrument to its present state of development. Light 

 filters are discussed by Dr. C. E. Kenneth Mees, and 

 magnetic rotatory power by Prof. T. M. Lowry. 



A long article on the optics of the microscope by 

 Prof. A. E. Conrady deals comprehensively with a 

 subject which normally receives inadequate attention. 

 There is a wide gap between the optics of the text-book 

 and that of the practical optician, and here we find 

 the gap bridged by an acknowledged authority. 

 Microscopy with ultra-violet light, and the enhanced 

 resolution that it effects, are the subject of a very 

 interesting article by Mr. J. E. Barnard. 



Commander T. Y. Baker sets out in a noteworthy 

 contribution the main underlying facts of navigation 

 and navigational instruments. The mathematics of 

 the Sperry gyroscopic compass are given, and the 

 author makes reference to the atmospheric difficulties 

 relating to the use of directional wireless. At times 

 there appear to be long tracks in the atmosphere 

 offering preferential facilities for the transmission of 

 wireless waves, while at sunrise and sunset marked 

 deviations may occur, directional errors of 20° or more 

 being of frequent occurrence. 



Mr. J. H. Sutclif?e unveils the mysteries of the 

 specialised technique of ophthalmic optical apparatus. 

 An article on optical calculations follows, by Mr. T. 

 Smith, of the National Physical Laboratory, who, in 

 association with Dr. J. S. Anderson, writes also on 

 optical glass, including in the article a wealth of numeri- 

 cal data. The working of optical parts by Dr. J. W. 

 French is a contribution of great practical interest, 

 while Mr. T. Smith's very readable monograph on 

 periscopes contains information much of which we 

 imagine must here be set out for the first time. A 

 lengthy and authoritative article by Mr. J. W. T. Walsh 

 on photometry and illumination is notably up-to-date, 

 and describes in detail the precision methods in use 

 at the National Physical Laboratory and elsewhere. 

 Photographic apparatus is treated very completely by 

 NO. 2805, VOL. I 12] 



Mr. C. W. Gamble, though the section on the modem 

 development of aerial cameras calls for lengthier notice. 

 Photographic lenses are dealt with by Mr. T. Smith, 



Prof. C. G. Darwin sums up very briefly the present 

 position of the quantum and radiation theories, in 

 physics, and this is followed very appropriately by 

 Dr. W. W. Coblentz's admirable discussion of radiation 

 from a practical point of view. 



Two useful contributions on radioat 1 1 \ 1 1 \ .md radium 

 by Dr. E. A. Owen might advantageously have been 

 permitted a lengthier treatment. The radium testing- 

 work of the National Physical Laborator)' has been of 

 vital importance to the radium market in Great Britain, 

 and we find the methods of test fully set out here. An 

 article on radiology deals largely with the industrial 

 developments of X-rays and the work of the National 

 Physical Laboratory on X-ray protection. 



The supreme importance of the short-base range- 

 finder in the War needs no emphasis here. It forms 

 the subject of an arresting contribution by Prof. F. J. 

 Cheshire. The fighting services in Great Britain have 

 favoured the " coincidence " type of range-finder, while 

 the Germans employed the Zeiss " stereoscopic " 

 pattern. In the laborator>' there appears to be little 

 in it as regards the two types, but under service con- 

 ditions it is easier to train men to get accuracy with 

 the coincidence type, an advantage which is emphasised 

 when an operator is working under the intense nervous 

 strain induced by modern warfare. The battle of 

 Jutland permitted a comparison between the two 

 types with almost identical base lines ; and on a 

 balance of evidence the coincidence type must, Prof. 

 Cheshire states, be given first place. 



Lord Rayleigh writes on the scattering of light by 

 gases, a subject with which his name and that of the 

 late Lord Rayleigh have noteworthy association. 



Prof. E. H. Barton has a long and interesting article 

 on sound and musical instruments in which is included 

 a good, if somewhat brief, discussion of the question 

 of the acoustics of buildings, a subject which is greatly 

 to the fore at present, and is now receiving attention 

 at the National Physical Laboratory and elsewhere. 

 Attention is directed to the investigations of Webster, 

 and in particular of the late Prof. Sabine in the United 

 States, work which is not sufficiently known in Great 

 Britain. We cannot afford to have many repetitions 

 of the new County Hall of London acoustical fiasco. 

 Prof. W. L. Bragg touches briefly on sound ranging, a 

 branch of militar)- activity in which, thanks largely to 

 the Tucker hot-wire microphone, AVe enjoyed con- 

 spicuous advantage in France during the War. 



Dr. T. R. Merton writes authoritatively on modern 

 spectroscopy. A very informative article on spectro- 

 scopes and refractometers by Mr. J. Guild includes 



