( 270 
twice as far from C, as the Weight at A ; and in gene- 
ral, let the make of the Engine be what it will, let the 
mechanical Powers be combined in any manner, when 
two heavy Bodies, by means of a Machine, ad: upon 
one another in different dired:ions, if their Velocities 
are reciprocally as their Maffes, they will deltroy each 
others Forces and come to reft. 
As this is true in relped: of mechanical Powers, lb 
it is in relped: to the Shock or Blow given by falling 
Bodies. An heavy Body, falling with an accelerated 
Motion, goes through a Ipace of one Foot in a quarter 
of a Second, and acquires a Velocity, which would * 
carry it two Foot in the fame Time with an uniform 
Motion ; the fame Body falls through a Ipace of four 
Foot in half a Second, and acquires a Velocity, that 
w^ould with an uniform Motion carry it eight Foot in 
half a Second. Therefore, as the Time of the fall 
through a Ipace of four Foot is twice the Time of a 
fall through one Foot, the Velocity in the' latter Cale 
is double that of the firft, and conlequently the Blow, 
that the Body will give, will be double. 
EXPERIMENT II. 
Fig. II. Let the Weight P of one Pound, be placed 
m the Scale fulpended at the end A, of the Ballance A B, 
which bears upon the Gnomon^ot Iron Supporter, khi. 
Then if the Weight C be let fall from D, or one Foot, 
it will by its Stroke on the end of the Beam B, raife 
up the oppofite end A with the Weight P,fb high, that 
the Springy ^ will fly from the Button /, which kept 
it ftreight and upright before the Shock. If the Weight 
P be of two Pbunds, it cannot be railed by the fall of 
C from any height lefs than F or four Foot ; whereas, if 
the force of the Shock was proportionable to the Space, 
X without 
