NA TURE 



65: 



THURSDAY, AUGUST 28, 1913. 



PR, I CTICA L HYDRA ULICS. 

 The Control of Water as Applied to Irrigation, 

 Power and Town Water Supply Purposes. By 

 P. A. M. Parker. Pp. vii+1055. (London: 

 G. Routledge & Sons, Ltd., 1913.) Price 21s. 

 net. 



THIS comprehensive and authoritative work 

 contains a wealth of matter relating to prac- 

 tical hydraulics which one might seek in vain for in 

 any other published book on the subject. In the 

 preface the author tells us that the book is the 

 product of actual engineering - experience, and is 

 mainly based on a collection of notes and formulae 

 accumulated in some eighteen years of profes- 

 sional work, during the major portion of which 

 he was engaged in independent practice, and that 

 therefore it must be regarded not as a text-book, 

 but rather as a manual for engineers in active 

 work. He also remarks that, " although the initial 

 knowledge assumed in the reader may be con- 

 sidered to be somewhat unusual, many portions of 

 the book have stood the test of everyday office re- 

 quirements in the hands of draughtsmen and 

 assistants." And it is only fair to say that an 

 examination of the work is entirely favourable 

 to the author on these points, although, of course, 

 in a work covering such a wide field, here and 

 there are matters of a controversial character, 

 which might be dealt with if the exigencies of 

 space permitted. 



The book contains the following chapters, 

 namely : i., preliminary data; ii., general theory of 

 hydraulics; iii., gauging of streams and rivers; 

 iv., gauging by weirs; v., discharge of orifices; 

 vi., collection of water and flood discharge; vii. , 

 dams and reservoirs; viii., pipes; ix., open 

 channels; x., filtration and purification of water; 

 xi. , problems connected with town water supply ; 

 xii., irrigation ; xiii., movable dams ; xiv. , hydraulic 

 machinery other than turbines; xv., turbines and 

 centrifugal pumps; xvi., concrete, ironwork, and 

 allied hydraulic construction ; (a) tables ; (b) 

 graphic diagrams. But these headings scarcely 

 give an adequate idea of the scope of the book, as 

 some of the chapters are divided into important 

 sections. For instance, in chapter xiv. we have : 

 section A, enlargements and contractions in pipes ; 

 section B, water hammer ; section C, ejectors and 

 syphons; section D, air lift and hydraulic com- 

 pressor; section E, hydraulic ram; section F, 

 resistance to motion of solid bodies in water ; sec- 

 tion G, impact of water on moving bodies. All 

 of these are important subdivisions, and they 

 appear to be handled in an entirely satisfactory 

 and convincing way ; but having- regard to the title 

 NO. 2287, VOL. 91] 



of the chapter, one looks in vain for any discussions 

 on the piston-pump and Humphrey's pumps, the 

 most important of all hydraulic machines. How- 

 ever, the hydraulic engineer has other books avail- 

 able in which these machines are fully dealt with, 

 and the author was wise in confining himself to 

 matters that do not so completely come within the 

 province of the mechanical engineer. 



Chapter vii., dams and reservoirs, is one of the 

 best in the book; the 130 pages devoted to this 

 important section will be appreciated by both de- 

 signers and engineering students. A valuable 

 feature of the work is that each chapter is pre- 

 faced by a list of its own symbols and a sequential 

 table of an extremely useful character, and many 

 of the chapters have also a summary of the equa- 

 tions and formulae. The mathematics used in this 

 lucid and most readable work are fairly easy, cer- 

 tainly to those accustomed to read works on 

 hydraulics. 



Another exceedingly valuable feature is the bib- 

 liography, as the book teems with references to 

 original authorities ; indeed, it is a standing 

 testimonial to the author's patient and untiring- 

 labours. He is to be congratulated upon producing 

 a work that will in all probability rank as high in 

 connection with applied hydralics as Bellasis's 

 work on hydraulics does in connection with 

 theoretical questions ; in fact, Mr. Parker's ency- 

 clopaedic work is the most notable book of the kind 

 that has appeared for many years, and it will 

 probably become a classic. H. J. S. 



SPHERICAL ASTRONOMY. 

 Lehrbuch der spharischen Astronomie. By Dr. 

 L. de Ball. Pp. xv + 387. (Leipzig: W. 

 Engelmann, 1912.) Price 20 marks. 



DR. L. DE BALL'S excellent treatise shows 

 abundant evidence of a long and careful 

 preparation. From the nature of the subject 

 striking innovations are not to be expected; it is 

 rather in the minute details of the exposition that 

 the merit of the present work is found. In some 

 places the mathematical treatment has been simpli- 

 flied, in others the discussion has been made more 

 rigorous and thorough. The author's long experi- 

 ence as a practical astronomer has led to improve- 

 ments in all parts of the subject, little in them- 

 selves, but when taken together making a notable 

 advance. According to the introduction, the book 

 is intended to be both a text-book for students 

 and a work of reference ; it is in the latter respect 

 that we commend it. Spherical astronomy is a 

 rather heterogeneous collection of but distantly 

 related problems, and a minute treatment of 

 isolated questions, many of which are only re- 

 quired in special researches and have no general 



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