Supplement to ''Nature" October lo, 1907 



all the world may secure, from the results we here 

 attain, uses and benefits much greater than those here- 

 tofore achieved." 



As America has only known anything of denatured 

 alcohol since the beginning of this year, Mr. Herrick's 

 anticipation has all the enthusiasm and optimism of 

 ine.\perience. At the same time, we shall look with 

 interest to the realisation of his belief. Meanwhile we 

 commend his book to the attention of those older 

 nations to whom the problem of denatured alcohol 

 has been familiar for generations past, in the hope that 

 their energies may be quickened and their inventive 

 genius stimulated by its perusal. 



WATER AND WATER POWER. 

 llydnndics. By Prof. S. Dunkorley. In two volumes. 

 Vol. i., Hydraulic Machinery. Pp. vii+343. 

 (London : Longmans, Green, and Co., 1907.) 

 Price los. 6d. net. 



HYDRAULICS, the practical side of the science 

 of hydrodynamics, is a subject of no little in- 

 terest and importance, not only from a technical, but 

 also from an historical point of view. The energy 

 contained in running water was one of tlie earliest 

 sources of power utilised for the service of man. 

 Water-wheels date back to a remote age, and are no 

 doubt coeval with windmills. It is interesting to 

 note that water power and wind power share the 

 unique distinction of being found in nature " ready 

 made," in which respect they stand apart from other 

 motive agencies, whicli have to be generated. 



It is mainly within a comparatively recent period 

 that the capabilities of hydraulic power for industrial 

 purposes have been thoroughly and systematically 

 exploited. No little of the initiative in this matter 

 was due to the genius and enterprise of the late Lord 

 Armstrong, whose inventive mind was, he tells us, 

 first set to work in this direction on the occasion of 

 a journey through the Craven district of Yorkshire 

 in 1S36. He was then struck by the large number of 

 mountain streams descending the steep slopes of the 

 hills and expending their energy to no apparently 

 useful purpose. Applying himself to the problem with 

 characteristic energy, he became the pioneer and 

 founder of the modern system of hydraulic power 

 transmission, which has had such an enormous vogue 

 during the past fifty years; and although at the 

 present time its popularity is threatened by the grow- 

 ing importance of its junior rival, electricity, yet there 

 still remains a vast field of usefulness for it which 

 it can never wholly lose. 



Prof. Dunkerley is thoroughly qualified to deal 

 with a subject of this kind, requiring, as it does, a 

 combination of close mathematical reasoning with 

 practical common sense. He divides his material into 

 two volumes, the first of which, and the one now under 

 review, is entirely concerned with the theory of 

 hydraulics in its relation to machinery. Dealing 

 primarily with fundamental principles, he lays down 

 the laws which have been demonstrated by experi- 

 ment, and then proceeds to describe the means of their 

 practical application. 



NO. 1980, VOL. 76] 



Admirable, however, as is Prof. Dunkerley's work 

 in its general scheme, we find that it bears here and 

 there several traces of a slight lack of care in pre- 

 paration, and some mistalces (due most likely to an 

 imperfect scrutiny of the proof»sheets) which it would 

 be well to correct in future editions. In certain parts 

 the book would appear to have been compiled some- 

 what disconnectedly, and without that sustained con- 

 tinuity of reasoning and progressive demonstration 

 which constitute features of a scientific treatise no 

 less essential than accuracy of detail and clarity of 

 diction. The author frankly admits that one article 

 (p. 192) is out of its proper sequence, and it seems to 

 us that other sections might have been more advan- 

 tageously arranged. For instance, we venture to 

 suggest that it vi-ould have been preferable for article 

 62 to follow directly after article 34, to which 

 it appertains, and there is no apparent reason 

 why the frictional resistance of bends and elbows 

 should be dealt with in widely disconnected sections 

 on pp. 56 and 87. 



Over and above some evident misprints of an 

 ordinary type, one or two strange inaccuracies seem 

 to have crept in. The rendering of Kulter for Kutter 

 (the familiar name of the Swiss experimentalist, who 

 with Ganguillet propounded the well known formula 

 now commonly known as Kutter's formula) is surely 

 a lapsus plumae of rather more than ordinary signi- 

 ficance, seeing that it occurs no less than four times, 

 and is nowhere given correctly. The formula for 

 bends, quoted on p. 87 as that of Weisbach, and pre- 

 sumably covering the general case, is certainly in- 

 complete, and should read : — 



' i' ' "' 

 where, for circular culverts, 



« = o-i3i+i-847f j^V', 



9 being the angle of deflection. Even supposing the 

 expression intended only to apply to rectangular bends 

 of circular section (which is not expressly stated, and 

 cannot be strictly inferred), the essential power index 

 is lacking. 



We mention these points in no carping and fault- 

 finding spirit, but simply by way of enabling such 

 few blemishes as there are to be removed. It is in- 

 finitely more pleasant to direct attention to the really 

 commendable features, which are not a few. A 

 number of worked examples are inserted throughout 

 the book. These have been so carefully selected, and 

 are so eminently helpful, that the author is to be con- 

 gratulated upon their introduction. Then, too, he 

 has been at pains to choose for his illustrations in- 

 stances of some of the more recent applications of 

 hydraulic science to engineering and commercial 

 operations, instead of confining himself to old-fashioned 

 types. A predilection for naval appliances is no doubt 

 due to his past association with the Royal Naval Col- 

 lege at Greenwich. In chapter iii. there are very full 

 details of the hydraulic gun brake and of the method 

 of operating bulkhead doors. Other articles worthy 

 of mention are those relating to the hydraulic ram 



