94 
FIFTH REPORT -1835. 
used, about of the weight of the first, 9 oz. 7 drs. each, one 
of lead, one of bell-metal, and the other of hardened steel. The 
recoils from equal impacts in all these, though very anomalous, 
tended toward equality as before. 
The beam here used was of steel, but that did not affect the 
results ; for the same equality in the recoils w 7 ill be found in the 
experiments on the 2nd beam, which was of cast iron. 
Conclusion 2.—If, as before, abeam supported at its ends be 
struck horizontally by bodies of the same weight, but different 
hardness and elastic force, the deflection of the beam will be 
the same whichever body be used. 
This conclusion is proved by the experiments upon the 2nd 
and 3rd beam, and with the same generality as in the former 
case. In those on the 3rd beam two balls 8^ lbs. each, one of 
lead and the other of cast iron, were made to strike the beam 
with velocities varying from 1 to 5 ; and the deflections from 
equal impacts by the two 
balls are as 
below: 
Velocity of 
Deflection from 
Deflection from 
Impact. 
Leaden Ball. 
Iron Ball. 
1 . 
... -42. 
. -42 
2 . 
. .. -82 . 
. -88 
3. 
... 1-23 . 
. 1-26 
4 . 
. .. 166. 
. 1-69 
5 . 
... 2-12 _ 
. 211 
In the impacts with the 4J lbs. balls of lead and beil-metal, 
the deflections from equal impacts, and varying in velocity from 
1 to 6, are as below, and nearly equal: 
Velocity. 
1 .. 
2 .. 
4 .. 
6 .. 
Deflection from Deflection from 
Leaden Ball. Bell-metal Ball. 
... -29 .. *31 
... *60 . -62 
M2 . M2 
1-73 . 1-65 
The same equality is shown too, though with greater anoma¬ 
lies than above, in the deflections from impacts with the balls 
of lead, bell-metal, and hardened steel, 9 oz. 7 drs. each. 
Conclusion 3.—The quantity of recoil in a body, after striking 
against a beam as above, is nearly equal to (though somewhat 
below) what would arise from the full varying pressure of a per¬ 
fectly elastic beam as it recovered its form after deflection. 
The fact in this Conclusion was sought for, because it seemed 
doubtful whether a bent beam would straighten itself with any 
nearer approach to the velocity arising from perfect elasticity 
than that given by the defective elasticity of the material of 
which it is made. Thus, two solid bodies of cast iron struck 
against each other recoil with only T 7 ^ of their velocity of im- 
