254 Notices of Books. [April, 



The Theory of Strains in Girders and Similar Structures, S=c. 



By Bindon B. Stoney, M.A. London : Longmans, Green, 



and Co. 1873. 

 The constantly growing demand for education, in every path 

 in life, must soon have the effect of replacing those hard-headed, 

 practical, self-taught, but untheoretical engineers who, it cannot 

 be denied, have been the pioneers of the profession, and to 

 whom credit is due for the construction of many important 

 and magnificent works. But, as is stated by Mr. Stoney in his 

 preface, " practice which was formerly excusable, or even 

 worthy of the highest commendation, would, now that knowledge 

 has increased, be proper y described as culpable waste." At 

 the present day, the engine ar requires not only to be a practical 

 man, but he should also be well acquainted with the physical 

 laws by which his works are regulated, so that he may at once 

 combine strength and refinement in his structural details. 



Nothing can be more important, in connection with engineering 

 structures, than a complete knowledge of the strength of the 

 materials employed, and this again requires to be augmented 

 with a full appreciation of the duty to be performed by each 

 portion of such structures ; in other words, of the strain or 

 stress to which each such portion is subjected, and of its capa- 

 bilities to resist it. The work now before us is a handbook to 

 such knowledge, so far as iron structures are concerned, accom- 

 panied by observations on the application of theory to practice, 

 and tables of the strength and other properties of materials, 

 compiled from such authorities as Hodgkinson, Tredgold, 

 Wertheim, Young, Fairbairn, Barlow, &c. 



The principle of strains is based on the fact that on the appli- 

 cation of force all bodies change either form or volume, or both 

 together. For convenience sake such strains are divided under 

 five heads, namely, tensile, compressive, transverse, shearing, 

 and torsional strains, according as they are caused by tearing 

 asunder, crushing, breaking across, cutting, and twisting asunder, 

 respectively. As the strength of any material depends ulti- 

 mately on its capability of sustaining strains, it is of essential 

 importance to know the ultimate resistance to tension or com- 

 pression which each material possesses, and thence deduce 

 those strains which may be safely imposed in practice ; and the 

 object of the present work is to put before the student in this 

 branch of science the results of the investigations, carefully 

 worked out, by those who have given more particular attention 

 to the subject. Besides the strains of tension and compression, 

 the elongation and shortening of the material subject to strain 

 claims attention, for experience has proved that the safe working 

 strain of any material does not exceed its sensible limit of uni- 

 form elastic reaction, generally called the limit of elasticity. 

 This limit may also be defined to be the greatest strain that does 

 not produce an appreciable set. 



