﻿Notices respecting New Books. 863 



Both authors are to be congratulated upon the lucidity of their 

 expositions of difficult problems, towards the solution of which 

 they have each made valuable contributions. Professor Love's 

 mathematical presentation of the subject is elegant and powerful, 

 the fundamental assumptions being clearly laid down, and the 

 interpretations of the formulae fully given. It is a model for all 

 future investigations along these lines. 



A Treatise on Dynamics, ivitJi Examples and Exercises. By 

 Andrew Gray, LL.D., F.H.S., and James Gordon Gray, D.Sc. 

 Macmillan & Co. Limited. London, 1911. 



Analytical Mechanics, comprising the Kinetics and Statics of Solids 

 and Fluids. By Edwin H. Barton, D.Sc, etc. Longmans, 

 Green & Co. London, 1911. 



No student aiming at higher work in Physics, Engineering, 

 and Astronomy, can afford to neglect the thorough studv or 

 dynamical science. To meet the needs of such students, Pro- 

 fessor Gray of Glasgow and Professor Barton of Nottingham have 

 almost simultaneously prepared and published the treatises named 

 above. It may be said at once that the three authors (for Pro- 

 fessor Gray has his son as collaborator) are to be congratulated on 

 the excellent manner in which they have done their work. "Which- 

 ever book the student takes as his guide he will be well led. Pro- 

 fessor Barton says that his " work is not written to any one 

 examination syllabus." Yet it is a pity that he should have 

 emphasised the examination system as an end-all by the explicit 

 mention of the examination papers from which he has culled 

 many of the examples. Most of those labled " Lond. B.Sc." do 

 not differ essentially from old familiar friends who first saw the 

 light in the Cambridge (Senate House perhaps a generation ago. 

 Very rarely has the examiner on the intermediate standard 

 produced a real original question during the last ten years. 

 What is here protested against is not the inclusion of the question 

 as a valuable exercise for the student, but the addition in capitals 

 of a certain examination it figured in, thereby tending to emphasise 

 unduly in the students' eyes this least satisfactory part of our 

 educational methods. 



The distinctive features of the books may be indicated by 

 the following comparisons. Professor Barton takes a wider 

 sweep over the dynamics of solids and fluids, discussing for 

 example the simpler problems of hydrodynamics and elasticity. 

 Professor Grav limits himself to particles and rigid solids and the 

 statics of flexible strings, omitting even Attractions and Potential : 

 but he carries the discussion into higher fields. Both authors devote 

 a chapter to gyroscopic motions; but here again, as was to be 

 expected in one who had been trained under Kelvin, Professor 

 Gray enters much more fully into the many problems which illus- 

 trate what Maxwell called ' gyrostatic domination.' Professor 

 Barton gives an interesting sketch of the recent attempts to 



