Velocities in kilometres per second. 
1918-19.] The Propagation of Earthquake Waves. 167 
Adding this to the previous result, we find for the whole evaluated integral 
the value 
1 = r 15-742 + 2 - 369 = 18 - 111 . 
hi J(p - 14) 
Equation (11) may now be written 
l°§e r — — ~ T ? 
7 r 
where all the quantities entering into I x must be expressed in fundamental 
units. Now f(p) has throughout been expressed in degrees of arc. The 
Distance from earth’s centre in thousand-kilometres. 
Fig. 5. 
numbers obtained by summation must therefore be divided by 180 /tt so 
as to express the arcs in radians. It does not matter in what units p 
