1550 
can be obtained indirectly by extracting the square root of 
E/E ; and these square roots are also given in Table II for 
comparison. It will be noted that the amplitude ratio near the 
critical angle is about 0.7 to 0.8 rather than 1.0. The 
amplitude ratio has no meaning at angles lying between 9, and 
glancing incidence. At glancing incidence, however, the bottom 
reflection is simply the inverted image of the incident wave, 
and from the point of view of the idealized theory, the amplitude 
ratio would be unity. Examination of the experimental records 
shows that the observed ratio again lies in the neighborhood of 
0.7 to 0.8. 
Energy loss due to viscous effects. 
13.1 We shall now proceed to extend the theory of sections 8 
and 9 in an effort to estimate the energy losses which may be 
ascribed to viscous dissipation. Making use of equation (66), 
supposing e“<O and taking C=O, we have: 
00 co ¢o8 
ye pat = Pct [ree POxp) exp(yl) dpat (125) 
. o C00 
The integration with respect to t gives P( X,-¥) if Re (-d% ) 
> & . Since Re ( ¥ ) = O for the integration over x » and 
A <O , this condition is satisfied. Therefore: 
c00 
[edt = 36 [Pld Pai) ty 
-¢00 
(126) 
