174 On the Measure of 
square of its velocity. However strange this 
opinion may appear, it is perfectly correct 
as far.as it is applied to the measure of force 
composed of the pressure and the time of 
its acting; for according to that measure, the 
quantity of force communicated will be always 
the same, whether.it be applied at G, D, or at 
any other point in AB. The progressive 
velocity generated m G, will, no doubt, be 
the same, at whichever of these points the force 
is communicated ; that is, the product of the 
mass into its velocity in the same direction 
will, in this case, as in all others, be as the 
product of the pressure into the time of its 
acting; and according to that measure, the 
whole effect of the force communicated is 
found in the progressive motion of the mass, 
the rotatory motion appearing to be produced 
without force. ‘The explanation most com- 
monly given of this inconsistency, is, that the 
rotatory motion consisting of equal quantities 
of motion in opposite directions, balances 
itself; but can it be shown that equal quanti- 
ties of motion in opposite directions may be 
produced without force? ‘Such is not the 
doctrine of Sir Isaac Newton; he certainly 
understood rotatory motion, as well as rectili- 
near motion, to be a measureable effect of 
force.—M. de Prony attempts to explain ‘this 
