Royal Society, 471 



Elementary Dynamics. With numerous Examples. By W. Gr. Will- 

 so^, M.A., L.O.E., Presidency College. Calcutta : Thacker, Spink, 

 and Co. 1874 (12mo, pp. 278). 



Our author tells us that, as regards the " arrangement, method, 

 and demonstrations " of the present work, " much has been derived 

 from Sir W. Thomson and Professor Tait's ' Treatise on Natural 

 Philosophy ; ' and, indeed, it is plain from the title-page that he 

 adopts their terminology, according to which the science of Mecha- 

 nics with its subdivisions, Statics, and Dynamics, is called Dynamics 

 with its subdivisions Statics and Kinetics. Consequently his book is 

 what would be called commonly an Elementary Treatise on Mechanics. 

 That its title is misleading is only an instance of the inconvenience 

 inseparable from the attempt to introduce a new Terminology, even 

 when it has well-founded claims to being an improvement on that 

 which it is designed to replace. There is not much room for novelty 

 in the contents of a volume written on a well-worn subject ; thus 

 the part on Statics, which fills half the volume, contains little or 

 nothing that may not be found about equally well done in several 

 elementary books. In other parts of the volume the influence of 

 our author's guides is more apparent : e. g., he explains the distinc- 

 tion between the gravitation and absolute units of force ; he gives 

 the three laws of motion as stated by Newton ; he devotes a suffi- 

 cient part of his volume to work and energy ; he separates the sub- 

 jects of Kinematics and Kinetics. - In most, if not all of these points 

 he adopts a course which others have already followed, and which 

 is not likely to be departed from by future writers of books with 

 the same aim as that before us. 



The examples are about three hundred and fifty in number, and 

 have been mainly taken from University Examination-Pap ers. 

 They are well chosen, and the answers seem to be correctly given; at 

 least they are so in the cases in which we have tested them. The 

 text of the work is written clearly and accurately ; and though the 

 author does not show any unusual power of elementary exposition, 

 his book will doubtless prove useful to the class which enjoys the 

 benefit of his oral instruction, and probably to others, though we 

 doubt whether it is likely to be much used in England. 



LXIII. Proceedings of Learned Societies* 



ROYAL SOCIETY. 

 [Continued from p. 395.] 



March 26, 1874. — Joseph Dalton Hooker, C.B., President, in the 



Chair. 



r J^HE following communication was read : — 

 -*• " On the Motions of some of the Nebiike towards or from the 

 Earth." By William Huggins, D.C.L., LL.D., E.E.S. 



The observations on the motions of some of the stars towards 



