1522 
where 
tg = (C/2a) —Aa (88) 
8.4 Since a is very small (it will be shown to be of the order 
of 1077 x é for length units in feet), the upper limit of in- 
tegration in equation (87) can be considered + OO for all 
practical purposes. Using this approximation, and introducing 
the parameters o< = A a; is = T /a, equation (87) becomes: 
BSP TS!) | exec y%) 
ae WT i v7 7 (89) 
x- G2 
In order to plot curves and perform computations with 
equation (89) it is convenient to introduce the form of the 
probability integral which is generally tabulated: 
Yy- 
Fe (y) = oS exp (-4*) Ay (90) 
Noting that Li 
fepty)ay.- 774 
equation (89) takes the form: 
exp Gee Ma Pi (e-aa){ aes 2 
(91) 
Pe) = 
exp (<A), , Prfy -x){, ~ <Pr 
eat aed J ( 
~ 46. 
