October 24, 1884.] 



SCIENCE 



407 



The work is professed^ based upon Ran- 

 kine's treatise, and is supplemented by a large 

 amount of other, and some new, matter. The 

 plan of the work is in some respects unusual. 

 Its first part is devoted to the statics of struc- 

 tures, the second to the kinematics of machines, 

 the third to the dynamics of machines, the 

 fourth to the strength and stiffness of mate- 

 rials, and the fifth to the transmission and 

 conversion of energy by machines. 



In part i. but little will be found to demand 

 special notice. The methods of graphical stat- 

 ics are adopted throughout, and are applied in 

 succession to the simplest and the more com- 

 plex cases. The straining action of a load 

 applied to a structure is considered in several 

 chapters ; shearing, bending, and twisting being 

 taken up in order. Cases of frames having re- 

 dundant parts, and the action of a travelling- 

 load, are given with propriety considerable 

 space. In part ii. we find the author follow- 

 ing Rankine in an innovation upon the standard 

 plan of text-books on mechanics as hitherto 

 constructed. Professor Cotterill here intro- 

 duces the studj- of the kinematics of machines, 

 — a subject not often considered to form a 

 part of this general division of the theor}* of 

 engineering, and only treated of, up to the 

 present time, to any considerable extent, in 

 separate works, as in Willis's and in Reuleaux's 

 well-known works. Rankine introduced this 

 subject, under the title ' Geometiy of mechan- 

 ism,' into his ' Machineiy and mill-work,' and 

 introduced it also in his ' Applied mechanics.' 

 This author has introduced to a limited extent 

 the nomenclature and methods of the latest of 

 the great masters of this division of the science 

 of engineering, Professor Reuleaux, and has 

 thus brought the matter fully up to the time. 

 A feature of the work to be noticed here, per- 

 haps even more than elsewhere, is the selection 

 of mechanism familiar to the engineer, and 

 where possible of those in common use, in 

 illustration of the principles to be explained. 

 Part iii., on the dynamics of machinery, as 

 would naturally be expected, occupies a large 

 amount of space. It opens with a statement 

 of the 'principle of work,' shows how resist- 

 ances are determined in common cases, de- 

 fines energy, illustrates the methods of its 

 transfer in machines, and considers the kinetic 

 form of energy as met with in f reel}'- moving 

 bodies and in machines. A chapter is devoted 

 to the dynamics of the steam-engine, and es- 

 pecially to the graphical representation of the 

 variation of effort and of energy at the crank. 

 All of this work is interesting and valuable ; 

 and the greater part of it is here for the first 



time, so far as the writer is aware, introduced 

 into the literature of the schools. 



The study of cases of incomplete constraint 

 and of straining actions in machines gives 

 the author an opportunity- to introduce the 

 principle of momentum and other dynamical 

 principles, and to illustrate their application 

 by the analysis of the governors and other 

 familiar cases. Part iv., on the strength of 

 materials, occupies more space than any other 

 division of the book. Impact, compound 

 stresses, and flow are as fulty treated as the 

 limits of the book permit, and more so than 

 is usual in treatises of this character. The 

 work of Professor James Thomson on the flow 

 of solids is described, and the experiments of 

 Tresca and of Wohler are cited. 



The volume includes in its last division, 

 part v., a discussion of the principles involved 

 in the transmission of energy by fluids, and of 

 its transformation. The flow of fluids, the 

 action of machines driven by them, and the 

 elementary principles of thermodynamics, are 

 here studied. 



An excellent feature of the book is its 

 references to works in which the subjects 

 treated are more fully developed by accepted 

 authorities. Examples are introduced at the 

 end of each chapter which are doubty inter- 

 esting as illustrating the special case there 

 treated, and as exhibiting applications occur- 

 ring in the engineer's practice. The engrav- 

 ings are numerous, and, in all cases in which 

 it is possible, drawn from working machines 

 and structures common in engineering. 



The work as a whole is one which will not 

 onl}' increase the reputation of its author, but 

 will earn for him the thanks of many instruct- 

 ors in technical schools who have long been 

 hoping for such a treatise as will permit them 

 to discard works, which, valuable in their da} T , 

 are now left behind in the forward movement 

 of the profession of engineering and of science. 



SCIENTIFIC BUTTER-MAKING. 



A manual for scientific butter-making. By W. H. 

 Lynch. Printed by order of the legislative as- 

 sembly. Toronto, Robinson pr., 1883. 15 + 

 204 p. 8°. 



The author, in the introduction to this man- 

 ual, expresses himself in sympathy with the 

 views advanced b}' Arnold and Bell on previ- 

 ous occasions, that all persons connected with 

 the prosecution of the daily business should 

 strive ' to make themselves familiar with the 

 principles on which success depends. These 



