April 5, 19 17] 



NATURE 



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simple methods are available. The author appears 

 afraid of making- undue demands on the know- 

 ledge of his readers, and when a real difficulty 

 occurs contents himself with a reference to a text- 

 book. 



The treatment of the strength of thick cylinders 

 and spheres may be cited as characteristic. The 

 final formula is evolved as the result of five succes- 

 sive approximations, and the whole investigation 

 takes up twenty-four pages. Would it not be really 

 simpler, as well as much shorter, to give the well- 

 known correct investigation at once? It is a little 

 more difficult, but there are no precarious assump- 

 tions, and by the time he had mastered it the 

 engineering student would really know something 

 about stresses and strains. 



These criticisms must not be taken to reflect 

 on the competence of the author, whose aims, as 

 recorded in his prefaces, are excellent. But he 

 does not seem to have a high opinion of the 

 attainments of the class of students whom he 

 addresses. 



OUR BOOKSHELF. 

 The Problem of Pain in Nature. By C. F. 



Xewall. Pp. 131 + 7 illustrations. (Paisley: 



Alexander Gardner, 1917.) Price 35. 6d. net. 

 This little book may be useful to those who are 

 troubled in spirit by what they believe to be a 

 fact : that animals in wild life suffer much pain. 

 Mr. Newall explains in a simple way why he 

 regards this shadow on Nature as, on the whole, 

 of man's imagining. For the humblest animals " no 

 brain, no pain" seems good sense; and animals 

 of the little-ljrain tyf>e, such as insects, the be- 

 haviour of which is predominantly reflex and in- 

 stinctive, often go on as if they were callous to 

 serious injuries. A dragon-fly which has lost its 

 hindquarters is not thereby hindered from eating 

 a good many flies, and finishing up with its own 

 lost parts. 



We cannot, of course, be sure how much sensa- 

 tion of pain there is among invertebrates, but 

 Mr. Newall's quiet consideration of the facts 

 suggests that there is but little. When we pass 

 to vertebrate animals the argument from analogy 

 becomes more trustworthy, and Mr. Newall refers 

 to the exf>eriences of men who have been in the 

 grip of wild beasts without feeling much, if any, 

 pain or fear. 



In most cases in wild life the coup de grdce is 

 Instantaneous. It may be argued, indeed, that 

 Nature is rich in efficiencies that lessen the chance 

 of pain. Selous was strongly of opinion that 

 Wallace erred in his low estimate of the evolu- 

 tion of pain-sensations among animals, but he 

 fiimself attached too much importance to cries 

 and the like. Many a one might conclude from 

 a baby's cries that the mother was slowly tor- 

 turing it. We think that there is good sense in 

 Mr. Newall's conclusion that men have greatly 

 exaggerated the prevalence of pain in Nature, but 

 we are afraid of some of the arguments, for they 

 seem also to banish pleasure. In a short book 

 NO. 2475, VOL. 99] 



like this the reader should be spared " amydallin," 

 "etherial," "Eperidae," "Barlett," and "Sir 

 James Lister," which we happened to notice. 



The Elements of Engineering Drawing. By E. 

 Rowarth. Pp. xii4-i3i. (London: Methuen 

 and Co., Ltd.) Price 25. 6d. net. 



The main purpose of this book is to give 

 examples of, and instruction in, the art of draughts- 

 manship, for the benefit of young students just 

 entering on an elementary course of engineering. 

 It is intended as a corrective to the unworkman- 

 like finish and execution which are apt to accom- 

 pany a too exclusive use of models and machine 

 parts, with their dimensioned sketches, in the 

 teaching of machine drawing. 



The general treatment of the subject is some- 

 what meagre and crude, but the plates are 

 executed in a style that would be approved 

 by the professional draughtsman ; the instructions 

 annexed to each plate are full and precise, being 

 helped by pictorial views; and the book seems 

 to be specially suitable for dealing with large 

 classes of junior students where it is not prac- 

 ticable to give much individual attention. 



The text is divided into four sections relating 

 to the manipulation of instruments, the method 

 of projection, and the forms and proportions of 

 the commoner machine fastenings, with examples 

 of their use. 



LETTERS TO THE EDITOR. 



[The Editor does not hold himself responsible for 

 opinions expressed by his correspondents. Neither 

 can he undertake to return, or to correspond with 

 the writers of. rejected manuscripts intended for 

 this or any other part of Nature. No notice is 

 taken of anonymous communications.] 



British Optical Science. 



As a manufacturer, may I be allowed to reply to 

 Sir Joseph Larmor's letter in Nature of March i on 

 the subject of British optical science, in which he 

 makes certain statements that must create an entirely 

 wrong and unfortunate impression of the circum- 

 stances? 



What is the reason for the comparative smallness 

 of the British optical industrv? If one considers the 

 pre-war output of the important German firms, it 

 will be seen that they are based upon their militan,- 

 departments of which the public of other countries 

 knows very little. It only knows the German firms 

 by their civilian productions. The German War Office 

 in peace-time issued large orders for optical instru- 

 ments and placed them with German firms, on the 

 principle that the optical industry would be a vital 

 one in time of war. Having such large orders to deal 

 with, and having the certainly of continuity of work, 

 the German firms were enabled to develop special 

 machinery and appliances and to develop their general 

 organisation. 



As suppliers of the largest Continental Army, the 

 German firms naturally obained the bulk of the 

 orders of other .Armies, with a consequent increase of 

 their facilities and experience. In such circumstances 

 it was comparatively easy to establish and maintain 

 a civilian world trade. 



Consider now the British conditions. The pre-war 

 British orders were of negligible importance compared 



