December 9, 1909] 



NA TURE 



155 



areas acquired here and there would not be satisfactory 

 for any purpose unless woven into a more complete 

 system by the teacher. An interesting experiment is 

 the inclusion of additional exercises, which are based 

 upon descriptions extracted from the volumes of the 

 Highways and Byways Series. They' are well chosen 

 to illustrate the different tvpes of English scenery, and 

 should be a useful link between aesthetic appreciation 

 and exact observation. 



OUR BOOK SHELF. 

 Carburettors, Vaporisers, and Distributing Valves used 

 in Internal Combustion Engines. By E. Butler. 

 Pp. xi + 176. (London: C. Gritlin aiid Co., Ltd., 

 1909.) Price 6i'. net. 

 Mr. Butler has written an interesting book on a 

 subject which hitherto has not had justice done to it; 

 and he is to be congratulated upon his bold decision to 

 devote a book e.xclusively to these matters of detail 

 instead of compressing them into the small space that 

 can be spared in books dealing with internal com- 

 bustion engines in their complete form. It cannot, of 

 course, replace the completer treatises, but it is an 

 excellent adjunct to them and is evidently written by 

 one who is thoroughly familiar with this side of the 

 work. 



The volume contains twelve short chapters, of which 

 the first four are concerned with surface and spray 

 carburettors for petrol and alcohol motors, carburettors 

 capable of automatically adjusting the air and petrol 

 supplies over a wide range of speed, and various types 

 of vaporisers for use with the heavy oils forming the 

 second distillate from petroleum. The remainder of 

 the book includes descriptions of various forms of ad- 

 mission and exhaust valves used on all classes of 

 internal-combustion engines, together with some 

 discussion of methods of actuating, timing, and water- 

 cooling^ them. 



Mr. Butler is an inventor on these lines, and has 



made himself familiar with what others have done 



in the same field; thus there are illustrations of no 



fewer than fifty-two different kinds of carburettor and 



vaporiser. With so much study of these matters, 



we wonder to find that he is apparently unaware 



of the increasingly common practice with motor 



vehicles of using the heat of the exhaust gases to 



warm, not the mixture as a whole, but the air supply 



only. The warm air is then passed over the jet and 



all the other arrangements are as usual. .'\t least 



equal economy is obtained in this way besides greater 



ease of fitting and a lowering of the prime cost. Even 



with so simplified a form of carburettor or vaporissr 



as this makes, it has been found that the cylinders do 



not require cleaning out at any more frequent intervals. 



.\s regards the valve mrchanisms, we are glad to 



find that the author has included a description of the 



Knight engine, and, further, that he has given a good 



deal of space to the discussion of sliding and rotary 



valves. We cannot but feel that the poppet type of 



valve is unlikely to be i)ermanently used, and the 



author deserves our thanks for having taken us some 



steps along the road towards a better form of valve 



mechanism. Many motor manufacturers are working 



in the same direction, and there is no doubt that we 



shall soon be hearing of other suggested forms 



of valve. Tf the experience of extended use of the 



Knight engine is favourable, it will give great impetus 



to this development. With the largest forms of gas 



engine there are, of course, already many engines mw 



running with complete success, using slide valve 



forms of control for either the admission or exhaust 



ports, or for both. 



NO. 2093, VOL. 82] 



Cotton Spinning Calculations. By W. S. Taggart. 

 Pp. xiv-i-335. (London : Macmillan and Co., Ltd., 

 1909.) Price 44. net. 

 Tin; author of this excellent and beautifully printed 

 text-book assumes that the reader has no special 

 equipment beyond an elementary knowledge of 

 arithmetic, and some acquaintance with the various 

 processes of cotton manufacture and the technical 

 nomenclature used in connection therewith. In the 

 introductory chapter, he gives general calculations 

 respecting the velocity ratio in wheel trains and belt 

 gearing; the surface velocities of rollers and the 

 stretching of fibres resulting from "draft"; the 

 estimation of " hanks " and " counts "; and the force 

 actions of levers. .\ set of exercises closes this part. 

 Ill succeeding chapters the treatment is more direct 

 and speci.'il. The various machines through yvhich the 

 material passes, from the Scutcher to the Ring Spin- 

 ning Frame, are considered in detail. The author has 

 h.-id the assistance of the leading manufacturers of tex- 

 tile machinery in the cotton district, and is thus able to 

 give diagrams, drawings, and tables of wheel teeth, 

 showing very clearly with full details the mechanisms 

 used in all the standard types of machines. The 

 calculations are therefore based on numbers represent- 

 ing the best modern practice. .V special chapter is 

 devoted to the consideration of epicyclic or differential 

 gears and the design of cone drums. Thus, by repeti- 

 tion, and by the wealth of illustration provided, no 

 reader should fail to obtain a thorough insight into 

 the action of the most complicated of the mechanisms. 

 This kind of quantitative work is essential if a student 

 is to have anything more than a superficial knowledge 

 of the subject, and it will enable him readily to calcu- 

 late the wheel changes, &c., necessary in order that a 

 machine shall be" able to cope with the varying 

 demands made upon it. 



The author concludes his very interesting volume 

 with a number of useful tables and an index. Both 

 author .and printers are to be congratulated on the 

 production of this admirable work, which should be 

 in the hands of everyone, at home and abroad, who is 

 interested in the practical working of textile 

 machinery. 



Proceedini(s of the .Aristotelian .Society. New series, 

 Vol. ix." Pp. 259. (London : Williams and Norgate, 

 1909.) Price loi-. 6rf. net. 

 Or the nine articles contained in this volume the 

 most important are, perhaps, Prof. Alexander's essay 

 oil " Mental Activitv in Willing and .Acting, ' and 

 Prof. Stout's rejoinder, ".Are Presentations Mental 

 or Physical?" The point at issue in these papers is 

 one of fundamental importance for both psychology 

 and the theory of knowledge, since _ Prof. 

 Alexander's contention, to put it quite plainly, is that 

 all mental activity consists .solely of conation and 

 feeling, or possibly, since it is conceivable that the 

 feeling or affective side of mental life may be reducible 

 to experience of successful and thwarted conation, of 

 conations alone. Hence he refuses to admit the 

 existence of such cognitive processes as have usually 

 been supposed to be denoted bv the names sensation, 

 imagination, perception. On his view the object 

 api:>rehended in all these processes is physical ; the 

 Process involved is simplv conation directed towards a 

 specific physical object. It follows, of course, that if 

 Prof. Alexander makes out his case, " presentations 

 nnist be deleted entirely from our account of the stuff 

 out of which mind is made, and, in the theory of 

 knowledge, anv doctrine which assumes either that 

 "we can only know our own sensations," or that, at 

 anv rate, we' begin by knowing our sensations and 



