May 1 6, 1895] 



NA TURE 



51 



MECHANICAL ENGINEERING. 



A Text-book of Mechanical Engineering. By Wilfrid J. 

 Lineham, Head of the Engineering Department at the 

 (ioldsmiths' Company's Institute, New Cross. (London : 

 Chapman and Hall, Limited, 1894.) 



MR. LINEHAM says that the desirability of writing 

 his book was suggested to him by the initiative of 

 the City and Guilds of London Institute in providing an 

 examination in mechanical engineering. In preparing 

 students for this examination he was led, he says, " to 

 consider seriously (i) whether the whole theory and prac- 

 tice of mechanical engineering, or even a precis of it, 

 could be compressed into one volume ; and (2) whether 

 it was desirable so to compress it." After examining Mr. 

 Lineham's book, we must confess to feeling grave doubt 

 whether the second question, at least, should not have 

 been answered in the negative before he set about the 

 execution of so very large a task. The ambition of the 

 attempt is, perhaps, more conspicuous than its success; 

 at the same time the book has good features, and 

 students of engineering may leam from it much that will 

 be valuable to them. It is a novel contribution to engineer- 

 ing literature : by no means wholly satisfactory, but still 

 one that should take a useful place. 



Mr. Lineham deprecates in advance the criticism which 

 he expects will be made on the compression of a vast 

 subject into a single volume, by citing ''the examples of 

 great and successful writers— to wit, Rankine, Ganot, 

 Deschanel, and others." We do not know whether both 

 adjectives are intended to apply to Ganot and Deschanel, 

 who, in any case, did not write on a subject which has a 

 practice as well as a theory. As to Rankine, who cer- 

 tainly did write great and successful treatises on engineer- 

 ing, the citation seems particularly unfortunate. To com- 

 press everything into one volume was exactly what Ran- 

 kine did not do. He wrote four or five large books deal- 

 ng with various branches of the subject, and did not 

 hesitate to repeat certain portions in more than one book 

 whenever that was necessary to make each intelligible 

 apart from the rest. Rankine's method and the author's 

 are as wide apart as the poles ; and of the two we prefer 

 Rankine's. Moreover, Rankine, in his great series of 

 text-books, dealt almost wholly with the rationale of 

 engineering; but here, in a single volume, more than half 

 the space is occupied by a description of the processes of 

 the workshop. 



It is in the descriptive portions that Mr. Lineham is at 

 his best. Probably no better general account of hand 

 and machine tools, and of the way to use them, has been 

 published. The pattern shop and foundry, the smithy, 

 the machine shop, fitting and erecting shops, all come in 

 for their due share of attention. The construction of a 

 horizontal engine is selected as a typical case, and is 

 described from start to finish with minuteness of detail 

 and with the aid of many admirable drawings. The 

 illustrations of the book are indeed excellent throughout, 

 both in style and matter. They are illustrations that 

 really illustrate. There are 732 of them, and all are 

 engineers' drawings. They have been prepared with 

 obvious care, and it would seem with unsparing labour 

 on the author's own part. They are treated in a way 

 which allows of their liberal introduction without much 

 NO. 1333, VOL. 52] 



expenditure of space. In a word, they are everything 

 that the illustrations in such a text-book ought to be. 

 The descriptive section of the book concludes with a 

 useful chapter on boiler-making and plate work, with a 

 somewhat extended account of hydraulic rivetting pro- 

 cesses, and with a short notice of electric welding. In 

 setting forth so much descriptive matter as this first part 

 includes, it is of course difficult to preserve in all parts a 

 proportion to which e.xception may not be taken. We 

 could wish to have seen more space given to the milling 

 processes, which take so prominent a place in modern 

 workshops. Nine or ten pages for hydraulic rivetting, and 

 a mere page and a half for the universal milling machine, 

 seems less happy a proportion than the author has 

 generally maintained. This, however, is a small matter ; 

 and it may safely be said that any engineering pupil or 

 apprentice will have his outlook widened, and his know- 

 ledge considerably increased, by reading the first part of 

 Mr. Lineham's book. 



To the study of the second part, however, he will do 

 well to bring some independent criticism. The first 

 chapter is on the strength of materials, and we had not 

 penetrated far without finding the ground shaky. Deal- 

 ing with the nature of shear stress, the author uses the 

 symbols /[, fc. andy"^ to indicate intensities of tensile, com- 

 pressive, and shearing stress respectively, and resolves 

 shearing stress into normal stresses inclined at 45° to it by 

 the equation 



fr ^ fr = fr 



. ■ . fc or f, = — -_ = . 



n'i> '■•*'•+ 



This is a bad start in a chapter which is to include refer- 

 ences to such subjects as the strength of thick cylinders, 

 the torsion of square shafts, and the effects of combined 

 bending and twisting in crank-shafts. 



Immediately after this error is the following paragraph : 



" On account of the cup or wedge fracture exhibited when 

 a specimen is broken by tearing or crushing, and for other 

 reasons. Prof Carus-Wilson argues that rupture takes 

 place by shear stresses at 45", either wholly or partially. 

 Certain it is that the three stresses are intimately con- 

 nected, and assist each other in destroying the cohesion 

 of the particles." 



We have not an intimate acquaintance with the con- 

 tributions which Prof. Carus-Wilson has made to this 

 subject ; but there is no evident reason why his authority 

 should be invoked in support of an idea which is 

 surely as old as the testing of materials. 



Turning to the paragraph headed " -Strength of square 

 shaft," we find a geometrical construction described at 

 some length, which is apparently based on Coulomb's 

 erroneous theory. The student who has taken the trouble 

 to follow this will feel excusably confused or irritated when 

 he goes on to read the subsequent lines : 



" St. Venant showed, however, in 1856 that Coulomb's 

 ring theory was not strictly applicable to any but circular 

 sections, and gave the following : 



Moment of square section = f, ('2085^) • 



because the greatest stress does not occur at the corners. 

 To illustrate St. Venant, Thomson and Tait have 



