1182 
wnere W is weight of charge in Ibs. 
P is external hydrostatic pressure in atmospheres. 
For depths from 0 to 90 feet, Py varies from 1 to 4 atmospheres and Dy is much the same 
as 0. given by (34). 
Taking (34) therefore as a reasonable estimate of the distance D. beyond which the 
assumption of a small amplitude wave is justified we have from (33) and bu), 
n 
On SK9) 
c 
(36) 
> 
Ro z D5 
Considering now the order of the value to be expected for B a we have 
Bas Oa = a (37) 
m sh 
where h is the plate thickness and s is the specific gravity of the plate relative to the water. 
For steel plates relative to sea water we take s = 7.7, whence 
where h and a are in same units OR 
a in feet 
ae pasha (38) 
h . 
h in inches 
For a smal) amplitude wave we thus have 
a 20 
pt a0, W in Ibs. 
Ba > 2 yi/3 (9) 
n J 
h in inches 
We thus see that except for small charges close to thick plates the value of @ a will be 
large, of order 10 or jreater. It may be noted that for the particular case considered in Report A 
of 300 1b. T.N.T. at 50 feet against 4 inch plate, Ra = 147, 
Tile Approximate solution for 6 a and e large. 
Let u and w be functions of Ro defined by 
Oman a VY Ree oor 
w= BR, - DV R.2 2 Ce 
2 tc ieee 
Then sree 
