Dr, Wollaston’s Lecture 
My object in the present Lecture is to consider which of 
these opinions respecting the force exerted by moving bodies 
is most conformable to the usual meaning of that word, and to 
shew that the explanation given by Newton of the third law 
of motion is in no respect favourable to those who in their 
view of this question have been called Newtonians. 
If bodies were made to act upon each other under the circum- 
stances which I am about to describe, the leading phenomena 
would occur, which afford the grounds of reasoning on either 
side. 
Let a ball of clay or of any other soft and wholly inelastic 
substance be suspended at rest, but free to move in any direc- 
tion with the slightest impulse ; and let there be two pegs 
similar and equal in every respect inserted slightly into its 
opposite sides. Let there be also two other bodies, A and B, 
of any magnitude, which are to each other in the proportion 
of 2 to 1 ; suspended in such a position, that when perfectly 
at rest they shall be in contact with the extremities of the 
opposite pegs without pressing against them. Now if these 
bodies were made to swing with motions so adapted that in 
falling from heights in the proportion of i to 4 they might 
strike at the same instant against the pegs opposite to them, 
the ball of clay would not be moved from its place to either 
side ; nevertheless the peg impelled by the smaller body B, 
which has the double velocity, would be found to have pene- 
trated twice as far as the peg impelled by A. 
It is unnecessary to make the experiment precisely as here 
stated, since the results are admitted as facts by both parties; 
but upon these facts they reason differently. 
One side observing that the ball of clay remains unmoved. 
