NATURE 



3CI 



THURSDAY, JUNE 20, 191 8. 



MASONRY DAMS AND IRRIGATiaN 

 WORK. 

 (i) Engineering for Masonry Dams. By W. 

 Pitcher Creager. Pp. xi + 237. (New York: 

 J. ^ Wiley and Sons, Inc.; London: Chapman 

 and Hall, Ltd., 1917.) Price 115. 6d. net. 

 (2) Irrigation Works Constructed by the United 

 States Government. By A. Powell Davis. 

 Pp. xvi + 413. (New York: J. Wiley and Sons, 

 Inc.; London: Chapman and Hall, Ltd., 1917.) 

 Price 215. net. 

 (1) ''T^HE engineering- term "dam" has a 

 -•- diversity of applications; it niiay be de- 

 fined to include any work which has for its object 

 the confinement of water, (a) so as to produce a 

 rise in level, (b) so as to exclude it from a certain 

 area, and (c) so as to repress the natural flow to 

 any desired extent. In Mr. Creager 's book the 

 subject is approached almost entirely from the 

 point of view of the adaptation of dams to the 

 formation of reservoirs in schemes of water con- 

 servation. The briefest reference is made to weirs, 

 anicuts, and the like, in river rectification opera- 

 tions, and none to dykes and embankments in 

 coastal defence works. The general location of the 

 dam is assumed to be already determined, and 

 the opening chapter deals with the selection of 

 the most suitable site for the former within the pre- 

 scribed area. As might be anticipated, the 

 volume is largely a reflection of American prac- 

 tice, with some few illustrations selected from 

 other countries; we miss, however, any reference 

 to English and French designs, some of which 

 iire certainly worthy of note. 



Within the purview chosen the treatment is 

 lucid and coherent. We confess to a dislike of 

 the use of numerals as points of reference in a 

 diagram, when the lines and areas they indicate 

 have numerical coefficients assigned to them : 

 there is always some possibility of confusion. But 

 this is a minor defect. Dams are divided into six 

 classes, of which only three come strictly within 

 the term "masonry dam." The author investi- 

 gates in careful detail the various external and 

 internal forces acting upon such structures. The 

 customary preliminary assumptions are made that 

 the dam is rigid and homogeneous, that the 

 foundation is elastic, and that the distribution of 

 basal pressure follows a law of uniform variation. 

 These assumptions are, of course, not strictly 

 correct, but Sir John Ottley and Dr. Brightmore 

 have shown that calculations based on them give 

 results which, at any rate, are not less than the 

 stresses actually experienced, and that they con- 

 stitute, therefore, a conveniently safe working 

 hypothesis. Indeed, in the present state of our 

 knowledge no other premises are practicable, and 

 the long-continued stability of existing dams 

 demonstrates the trustworthiness of the principles 

 which have been adopted in their design. It is 

 NO. 2538, VOL. lOl] 



true that Mr. Atcherley, in "his theory of tension in 

 vertical planes, has attacked the soundness of the 

 position, but the weight of evidence is undoubt- 

 edly against him. The author notes the contro- 

 versy briefly, but, in view of the vital importance 

 of the matter, we venture to think that the refuta- 

 tion of Mr. Atcherley 's contention (ably ' main- 

 tained as it was by Prof. Karl Pearson) by the 

 experimental investigations of Ottley and Bright- 

 more, and also by those of Messrs. W^ilson and 

 Gore, is deserving of rather more than passing 

 allusion in a footnote. If the postulates, how- 

 ever, be conceded, the rest of the reasoning 

 follows. The author lays down six rules which 

 govern the design of masonry dams in all 

 essential respects. Each of these rules is then 

 expressed in the form of a mathematical equation, 

 belonging to one or other of two classes, which 

 are termed respectively equations of determination 

 and equations of investigation. The former of 

 these fix the length and location of successive 

 joints ; the latter decide whether the results so 

 obtained are compatible with the proportions 

 I adopted for adjacent sections and 'the design as 

 a whole, the process being, to. a large extent, one 

 of "trial and error." Following this, a series of 

 examples is worked out in numerical and 

 graphical detail, including two solid non-overflow 

 dams, a solid spillway dam, and two hollow (re- 

 inforced concrete) dams. Arched dams are also 

 treated and illustrated, but we are a little sur- 

 prised at the absence of any comment on the Bear 

 Valley Dam in California, which is remarkable 

 for its extremely slender proportions ; if we mistake 

 not, the line of theoretical pressure, reservoir full, 

 lies almost entirely outside the profile. 



Some observations on noteworthy instances of 



failure- — at Bouzy and Habra, for example — would 



have been serviceable, and the expenditure side 



of the question certainly deserves consideration ; 



j but no particulars of cost are given. Taking it 



I as a whole, however, the work will undoubtedly 



■ prove a useful text-book for students and 



I draughtsmen, and we desire to express every 



I appreciation of it as such ; but it will scarcely be 



i claimed by the author that he has exhausted the 



i subject. 



! (2) In quite a number of respects, Mr. Davis's 

 volume is complementary to that of Mr. Creager. 

 [ He gives a series of* articles on reservoir work 

 carried out in the United States, including de- 

 : scriptions of the dams, with detailed statements 

 I of cost. Some of these dams are discussed and 

 illustrated by Mr. Creager, but Mr. Davis's 

 ' presentment is less theoretical and more prac- 

 tical, and his range is more extensive, since he 

 includes timber and earth, as well as masonry 

 structures. At the same time, his survey is limited 

 to irrigation works undertaken by the Reclamation 

 Service of the L'^nited States Government. The 

 book is an appropriate record of a great State 

 I enterprise which has resulted in the provision of 

 I reservoirs and distributing systems whereby water 

 j is available for the irrigation of nearly two million 



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