898 
M Cas 
Sicha lary ei UN a aS tg 
° 
Finally the two anproximations may be made simultaneously to 
give the incompressive, central equation 
(sits eRa, FPR) 2, 1 cam ORS 
Since the radii of the pistons in current use are small, the 
differences between equations (7,1), (2.2), and (7,3) are also 
smell. They were compared numerically for a crusher gauge with 
the following constants. 
M=14.0¢ 8, = 82.0 10-© see 
R = 0.60 em 0, = 82.4 107© sec 
@, = 4.0 1075 sec 
In the incident pulse, ® = 500 1075 sec 
Equatione (7,]) and (7.3) differ only in effective mass and in 
that by lese than 1%. Numerical integration of (7,2)' gave a 
uaximum displacement differing from the corresponding quantity 
for (7,3) aleo by lese than 1%. This result also shows that it 
fe legitimate to neglect the higher order terms in equation 
ase) iis 
The Brror in the Incompressive Approximation 
8. During the action of the gauge, the acceleration of the viston 
ie always decreeeing, after its initial Jump, since the voreseure 
is falling, while mase and resistance are increasing. Hence at 
32 
