PROPAGATION OF SEISMIC WAVES 155 
The values of these constants were obtained by a least square solu- 
tion which included all points representing wave paths lying entirely 
in the upper laver. By use of the following equations 
V =20T + 8, (2) 
b/sin 0) = v/sin@ = V, (3) 
P = 6?/87a(sinh q= @) 5° (4) 
g = 2 arc cosh V/b 
Surface. 
Alluvial Material 
Limestone 

fe) 200’ 
West are 
Fic. 1.—Time-distance curves and approximate section at Green Pond. 
the velocity depth relation is determined. Here V is the velocity at 
the midpoint of the path of length X and maximum penetration P, 

Fic. 2.—Diagram of wave path. 
and 6» is the emergence angle for this path. Figure 2 illustrates the 
meaning of each of these symbols. The velocity-depth curve thus 
obtained is shown in Figure 3. 
3 Ewing and Leet, Trans. A.I.M.E., Geophysical Prospecting, 1932. 
815 
