THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FIFTH SERIES.] 



JUNE 1887. 



LVI. The Laws of Motion. By Robert Fkanklin Muirhead, 

 B.A.j of St. Catharine's College, Cambridge*. 



Preface. 



THE aim of this Essay is to state in the clearest manner 

 possible the best existing conception of dynamical 

 science. The writer believes that the statement of dyna- 

 mical principles here given is to be found implicitly in 

 the reasonings of the best modern masters of the science, but 

 that it has never hitherto been stated explicitly. The general 

 statement indeed has sometimes been made that the proof of 

 a hypothesis or theory is its agreement with the facts, or that 

 the whole Principia is the proof of the Laws of Motion. 

 But I have pointed out in detail that the very conceptions 

 and definitions of Dynamics are unintelligible when taken 

 singly. I have endeavoured to free the science of Dynamics 

 from survivals from its childhood, in the shape of extra- 

 kinetic definitions of dynamical concepts, and a priori 

 assumptions. 



The Laws of Motion, 



In view of the enormous development to which the science 

 of Dynamics has attained in modern times, of the simplicity 

 of its fundamental conceptions, and of the unquestioned 



* Communicated by Professor James Thomson ; being the Essay to 

 which the second Smith's Prize was awarded in 1886. 



Phil. Mag. S. 5. Vol. 23. No. 145. June 1887. 2 K 



