C 6 °7 3 
VI IT. A fhort Account of 2)r. Jurin’j Ninth and 
lafl Tiiffsrtation De Vi Motrice, by Mr. 
John Eames, F. R. S. 
HE laft Dififertation is * new, and treats of the 
Motive Forces of Bodies, whether they are to 
be eftimated by the Velocities, or the Squares of the 
Velocities, when the M a fifes are equal. The Ori- 
ginal of this Difpute among the Mathematicians, the 
Author aferibes to a Slip committed by the cele- 
brated Mr .Leibnitz,-, in the Year i68<5. and the Con- 
tinuance, to the Negleft of the Times, wherein equal 
Effefts are produced. The one Side aflerts all Caufes 
to be equal, whofe Effefts are lo, whether the Times, 
during which the Caufes aft, are fhortcr or longer. 
The other, on the contrary, maintains, that equat 
Effefts may arife from unequal Caufes, if the Times 
ofAftion are unequal ; that confequently the Times, 
as well as the Effefts, ought to be taken into the 
Account. 
He wifhes the Gentlemen on the other Side of the 
Queftion would produce fome Experiment in their 
Favour, where the Equality of the Times is preferved 5 
fince all the Experiments they have hitherto made, 
and argued from, may juftly be fet afide, as incom- 
petent, on the Account of the Inequality of the Times 
of Aftion. 
* The Eight preceding Differtations had been before printed 
feparately } but were now all collected together, with the Addition of 
this Ninth, and publilhed in one Volume in Ottavo, London ^ 1732. 
The 
