Moving Force. 253 



brought forward by Dr. Wollaston involving collision and 

 change of figure, which has been understood to prove that 

 the force of a body in motion may be properly estimated 

 either by the duration of its action or by the space through 

 which it acts according to the particular views which may 

 be taken of the phenomena. Ewart thinks that it admits 

 of the same explanations as some oi those which have 

 already been examined. 



Ewart concludes with a simple application of the 

 principle which he endeavours to support, and the resolu- 

 tion of compound moving forces. 



Having given the above remarks on Mr. Ewart's paper, 

 we add also Mr. Hodgkinson's, written some years earlier 

 than the above. 



Some Account of the late Mr. Ewart^ s paper on the ^Measure 

 of Movijig Force," &c., by Eaton Hodgkinson, F.R.S. 

 {read April 2,0, 1844), pp. 138 to 144, Vol. XI I. 



The subject of this paper formerly caused a great con- 

 troversy ampng mathematicians, which continued for thirty 

 years or more, and was then dropped about a century ago. 

 Since which time an idea has been generally entertained 

 that it was only a dispute about terms. 



The advocates on one side, including Leibnitz, the 

 Bernouillis (John and Daniel), Hopke, Huygens, Wolfius, 

 Gravesande, Musschenbroek, &c., maintained that the force 

 of bodies in motion ought to be estimated by the quantity 

 of matter multiplied into the square of the velocity ; whilst 

 the other side, called Newtonians, and including the names 

 of Maclaurin, Pemberton, Desaguliers, Clark, Jurin, and 



