August 4, 1923J 



NA TURE 



155 



» 



to give supplementary teaching as well as general 

 advice and assistance will, we hope, receive attention. 

 We think that this is one of the most important of the 

 recommendations. It is, in fact, no new departure, but 

 at present the need for such work is not generally 

 realised, and the number of clinics to which workers 

 are attached is limited. 



The work of ante-natal clinics is strongly commended. 

 The position to-day as regards congenital syphilis is 

 extremely encouraging. It seems within the bounds of 

 possibility that inherited syphilis may cease to exist 

 some day, so effective is the treatment of the syphilitic 

 mother during pregnancy in securing a healthy baby, 

 though sufficient time has not yet elapsed since the 

 beginning of ante-natal treatment for any one to say 

 that so insidious a disease as syphilis can be wiped out 

 with certainty in every case. 



A short paragraph summarily directs attention to three 

 sources of disease which need tackling, although they 

 present serious administrative problems. The three 

 sources mentioned are infected immigrants, infected 

 seamen, and infected mental defectives. The matter 

 of arrangements for the treatment of infected seamen 

 has already received much attention, but more remains 

 to be done. The adequate care of the slightly feeble- 

 minded and infected individual is of great importance 

 to the community ; as a focus of infection he or she 

 may do an infinite amount of harm. No amount of 

 teaching will develop a sense of responsibility, and 

 temporary or permanent control is necessary. 



The report shows us, in conclusion, how best to lay 

 out our limited pubUc money : first, in the treatment 

 of disease ; secondly, in teaching the public about the 

 diseases ; thirdly, in improvement of the conditions of 

 living, i.e. houses, general education, and facilities for 

 healthy recreation. It ends by directing attention to 

 the decline in the numbers of sufferers from venereal 

 diseases as shown by the clinic figures during the last 

 two years. As, however, these still show an enormous 

 prevalence of disease, no relaxation of effort can be 

 allowed. The work of education on the subject of 

 disease is, moreover, one that must be continued for 

 all time. We cannot hope that venereal diseases will 

 ever cease to exist, and their control will always depend 

 on the enlightenment of the public. It is to be hoped 

 that this report, issued at the very low price of T)^., will 

 be widely read, for it concerns a subject of world-wide 

 importance, and any summary discussion must neces- 

 sarily leave untouched many important points with 

 which it deals. 



Lord Dawson, through whose efforts the committee 

 and consequently this report came into being, is to be 

 congratulated on the performance of a valuable public 

 service. 



NO. 2805, VOL. I 12] 



Physics and its Applications. 



A Dictionary of Applied Physics. Edited by Sir 

 Richard Glazebrook. In 5 vols. Vol. 4 : Light 

 — Sound — Radiology. Pp. viii + 914. (London : 

 Macmillan and Co., Ltd., 1923.) 635. net. 



THERE was a time, not so very long ago, when 

 the student of physics could reach down from 

 his shelves " Ganot " or " Deschanel " and, " laying 

 flattering unction to his soul," could proceed to master 

 their contents with the comforting if misguided assur- 

 ance that here all useful knowledge was displayed. 

 No such vanity of outlook is possible to the present-day 

 student. The physics of this generation is teeming with 

 such vitality, is making such gigantic strides and devour- 

 ing at such a pace the boundaries of its sister sciences, 

 that it threatens to overwhelm those of its devotees 

 who vainly seek to achieve an all-round distinction. 



The full truth of this is patent to the reader (and 

 reviewer) who has attempted to survey the amazing 

 compendium of knowledge in the various volumes of 

 the " Dictionary of Applied Physics " which have been 

 issued under Sir Richard Glazebrook's editorship. 

 The Dictionary has become, as it was bound to become, 

 a pillar of physical science and a fascinating mine of 

 information, indispensable alike to the teacher, student, 

 and investigator. One had been tempted to wonder 

 whether the high standard set in the earlier volumes 

 could be sustained, but a critical survey of the latest 

 new-comer is amply reassuring. Sir Richard goes on, 

 in fact, from triumph to triumph. Volume 4, which 

 is devoted to light, sound, and radiology, shares in 

 common with its predecessors a clarity, vigour, and 

 " first-handedness " which are characteristic only of the 

 investigator who is in close contact with his subject 

 and endowed with the art of expounding it. 



By far the greater part of the present volume is 

 occupied with optical subjects. The first article is 

 one by Dr. A. E. H. Tutton, who gives a short account 

 of crystallography dealing, inter alia, with a number 

 of ingenious instruments of his own design which have 

 been employed in his extensive and well-known 

 researches. Dr. John A. Anderson, of the Mount 

 Wilson Observatory, refers briefly to the manufacture 

 and testing of diffraction gratings. One learns that 

 the general impression which prevails that the con- 

 struction of a successful ruling machine is bound up 

 with the manufacture of a perfect screw is erroneous. 

 It is not difficult to make screws uniformly accurate 

 to 117777^(^X7 i"ch, but much more difficult to avoid errors 

 due to faulty mounting. " The Theory of Diffraction 

 Gratings," by Mr. J. Guild, of the National Physical 

 Laboratory, forms a succinct though abbreviated 

 companion article to Dr. Anderson's. Mr. Guild is 



