C 439 ] 
it had before by the Motion of the Plane, now intirely 
deftroy’d, and will be abfolutely at Reft. 
But the Body, which is pufhed forwards, will now 
have the Velocity 2, namely 1 from the Motion of 
the Plane, and 1 from the Action of the Spring. 
Thus far every body agrees in what will be the 
Event of this Experiment. 
But the Qucftion is, What will be the moving Force 
of the foremoft Body, or of that which is pufhed for- 
wards, and which has the Velocity 2 ; viz. 1 from 
the Motion of the Plane, and 1 from the Action of 
the Spring. 
By the Leibnitian Dodlrine, its moving Force muft 
be 4. : And, if fo, it muft have received the moving 
Force3 from the Adtionofthe Spring; for it had only 
the moving Force 1 from the Motion of the Plane. 
Let us examine, whether this be poflible, or rc- 
concileable to their own Dodlrine. 
Their Dodlrine is, That equal Springs, equally 
bent, will, by unbending themfeives, give equal 
moving Forces to the Bodies they adt upon, whatever 
thofe Bodies are. 
We agree to this, not generally indeed ; but in the 
Cafe before us, where the Bodies are of equal Maftcs 
or Weights, we agree to it. 
Let us therefore imagine the bent Spring, which 
is placed between the two Bodies, to be divided tranf- 
verlly into two equal Parts. In this Cafe it is plain, 
that the two Halves of the Spring, may be confidered 
as two intire Springs, equal, and equally bent, each of 
which refts at one End in <iyEquilibrio againft the 
other Spring, and at the oppolite End, preftes againft 
the Body it is to move. 
K k k z Con- 
