February 3, 1910] 



NA TURE 



595 



only with the mathematical investigation of the sub- 

 ject ; the experimental side is entirely omitted. The 

 attempt to compress into one small table (p. ii) the 

 average values of the tenacity, shearing strength, &c., 

 of the chief materials of construction has led to the 

 insertion of figures likely to mislead the unwary ; 

 for example, the tenacity of steel is given as 110,000 lb. 

 |)er square inch ; as a matter of fact, the tenacity of 

 most of the mild steel used in constructional work 

 lies between 60,000 and 70,000 lb. per square inch. 

 Again, the shearing strength of wrought-iron is given 

 as 20,160 lb. per square inch; this is much too low 

 a figure ; it is less than half the average value of the 

 shearing strength of wrought-iron rivets and pins in 

 double shear. 



Each chapter has a series of examples to illustrate 

 the formulse which are deduced in that chapter, and 

 the answers are in many cases appended; it is notice- 

 able that these answers have a defect, by no means 

 uncommon in text-books of this class, to which atten- 

 tion has often been directed, and which can best be 

 explained by quoting a specimen answer. The 

 student has to determine from certain data the 

 diameter of a wooden spar used as a beam ; the 

 answer appended to the question is 7*0025 inches ; of 

 what value are the figures to the right of the decimal 

 point? Ill a subject like strength of materials, one 

 of the first lessons which the student should learn is 

 that the numerical data which he proposes to use in 

 some mathematical formula may, for obvious reasons, 

 s^ary by some quite perceptible percentage on either 

 side of a mean value (the value he proposes to use), 

 and that, therefore, he can expect to obtain a solution 

 which is only approximately correct, hence to work 

 out a solution to the degree of accuracy of that in 

 the example quoted above is not only a waste of time, 

 but is positively misleading. It is to be hoped that 

 in any future edition these answers will be revised. 



The effect of combination of stresses is dealt with 

 in chapter v. in a clear and simple fashion, and it is 

 refreshing to find this portion of the subject taken up 

 at such an early stage of the work, and its import- 

 ance impressed upon the student. 



The book concludes with a number of miscellaneous 

 problems, such as reinforced concrete beams, stresses 

 in thick cylinders and guns, &c. 



The book will probably prove an acceptable one to 

 young engineers who are just beginning the study of 

 this important subject, and want to get a general 

 insight into it before they begin to work at one of the 

 more advanced and complete text-books. 



(3) As the author points out, there are numerous 

 elementary text-books on steel structural design, but 

 there has been a distinct want of an elementary work 

 on the design of masonry structures. This book will 

 supply this need, for it explains just those underlying 

 principles which the beginner finds it troublesome to 

 understand. 



It is difficult to follow the author's reasoning in 

 chapter i., when deducing the safe compressive load 

 for masonry; surely if it took 900 tons per square 

 foot to crush a specimen of granite, there must have 

 been a shearing stress when rupture occurred (most 

 NO. 2I0I, VOL. 82] 



probably by shearing) of something like 450 tons per 

 square foot, and, therefore, the method of deducing 

 a safe compressive working stress given on p. 10 is 

 hardly logical. 



The branches of masonry design dealt with include 

 walls, piers, brackets, simple arches, vaults and skew- 

 arches, domes, and retaining walls and dams ; the 

 treatment of each branch is sufficiently complete for 

 all the practical cases the young civil engineer or 

 architect is likely to meet with, all the more complex 

 theories being wisely omitted. 



The last chapter deals in brief fashion with re- 

 inforced concrete, the essential principles of this 

 system being fully explained. 



POPULAR NATURAL HISTORY. 

 (i) Atiimals and their Ways. An Introduction to the 

 Study of Zoology and Agricultural Science. By 

 E. Evans. Pp. viii + 184. (London: J. M. Dent 

 and Co., 1909.) Price i.s. 4(i. 



(2) The Hedge I Knoxv. Edited by W. P. Westell 

 and H. E. Turner. Pp. 77. (London : J. M. Dent 

 and Co., 1909.) Price &d. 



(3) The Pond I KnonK Edited by the same. Pp. 78. 

 (London : J. .M. Dent and Co., 1909.) Price 8d. 



(4) Butterflies and Moths shou<n to the Children. By 

 Janet H. Kelman, described by Rev. Theodore 

 Wood. Pp. xvi+94. (London and Edinburgh: 

 T. C. and E. C. Jack, 1909.) Price 2S. 6d. net. 



(5) .Yf.'ifx and Eggs shoivn to the Children. By A. H. 

 Blaikie, described by J. .'\. Henderson. Pp. xvi + 78. 

 (London and Edinburgh : T. C. and E. C. Jack, 

 1909.) Price 2s. 6d. net. 



(6) The Backwoodsmen. By Charles G. D. Roberts. 

 Pp. 317. (London: ^^'ard, Lock and Co., 1909.} 

 Price 6s. 



(i) A LTHOUGH the title of this review of the above 

 ■^^ series of books might lead one to suppose that 

 this book would be a popular account of the lives and 

 habits of animals, it is unfortunately necessary to point 

 out that such an idea would be fallacious. It is a 

 matter of regret that the author should have chosen 

 a title which, to our minds, does not convey a correct 

 idea of the contents. The reason may be that we 

 have been spoilt by the previous publication of one or 

 two excellent little works on animal life, and that our 

 criterion has been raised. Be this as it may, the 

 author has not succeeded in doing justice to his theme, 

 and we cannot imagine any young student being filled 

 with enthusiasm for zoological science, still less agri- 

 cultural science, after having had this introduction. 

 That the author must be a botanist is evinced by such 

 a word as "Crustaceas" (p. 170). The illustrations 

 are poor. Fig. 3 being especially crude ; and an 

 acknowledgment of the source of such figures as are 

 taken from the publications of the U.S. Department 

 of .Agriculture, which are good, should surely be given 

 under the figures, as is customary. 



(2 and 3). These small books of the same series are 

 marvellous examples of cheap printing, and are un- 

 accompanied by the usual inferior illustrations; they 

 are well illustrated, and, on the whole, are written in 

 simple language. It probably would have been pre- 



