SURFACE REFLEXION OF EARTHQUAKE WAVES. 
3 77 
If, however, we take the surface values given by Zoppritz, viz., Y x = 7"17 km. per 
second, V 2 = 4'01 km. per second, we have g = 1'788, and A 2 does not vanish for any 
real value of e, but falls to a very small minimum about e = 20°. 
The numerical values of A 2 , A 3 , H, and V for dilferent angles of impingence are 
given in Table I., and the results are also shown graphically in fig. 2, wherein A is 
taken as numerically —1. 
Degrees 
Angle of impingence — Longitudinal wane incident 
Fig. 2. 
(2) If the incident wave is transversal and the vibration at right angles to the 
plane of the paper there is no reflected longitudinal wave for any angle of incidence, 
and the reflected transversal wave at an angle e is equal in magnitude to the incident 
wave. The resultant motion of the ground is entirely horizontal at right angles to 
