441 
From Eqs. 6.2 and 6.7, we easily obtain the interesting but of course 
rough estimate of e) ’ 
B= U12s5 RP Pro "4 Ria (6.8) 
ath g 6 is expressed in milliseconds, R in meters, and Pe in kilobars. 
The factor 0.125 is to be replaced by 0.017 if R is expressed in feet, 
Pa in tons/in.* and common logarithms are used, 
Thus far we have considered the parameter Y as constant 
throughout the pulse. This is not strictly true, and in fact the 
approximation formulas of Section 7 are somewhat inaccurate as a re- 
sult. At small values of G.(v) » & approaches unity and the distor- 
tion of the time scale is removed, Thus, while the crest of the ini- 
tial pulse will be considereably spread out in time, its tail will 
arrive with practically the same time scale as that with which it 
originated on the gas-sphere surface. 
A rough approximation to the time scale without use of the 
peak approximation may be obtained in another way. Remembering that 
ye is (ot /or), and integrating the second of Eqs. 6.2, we get 
ne eee b Ria, (6.9) 
t ca a é 
where 7 is identical with the time of decay of Eq. 6.8. Although 
the linear decay of pressure as a function of time, embodied in Eq. 6.9, 
is too crude an approximation for practical purposes, it is of some 
interest in showing that there is no reason to believe that a very 
54 
