163 
1918-19.] The Propagation of Earthquake Waves. 
to be applied. It was in the hope that Turner might be able to supply 
me with better data that I reserved the final calculations for a whole year 
after the method of attack had been planned and partly carried out. But 
the subject bristles with grave difficulties, and although in recent B.A. 
Reports Turner has indicated probable corrections at special parts of the 
tables, I felt that it would be sufficient meanwhile to adhere to the presently 
accepted values. These are reproduced in the Appendix, Table A. 
(2) The Reduction of the Data in a form suitable for the Evaluation 
of the Integral Equation (11). — In the table in the Appendix the times of 
transit of both the Primary and Secondary waves are given for every 
integer number of degrees , to the arc. That is, T is given in terms of 2a. 
From these tabulated values appropriate mathematical methods lead to 
the determination of 0T /da for every chosen value of « ; and this is the 
quantity p. It is abundantly clear that the probable error in this quantity 
is considerable. Let the values of p be now plotted on a sufficiently large 
scale in terms of a, and through the points so obtained let a continuous 
graph be drawn. From this graph let a new table be constructed giving 
the values of a corresponding to successive equidistant values of p. The 
graphs are shown in figs. 1 and 2, and the new tabulations are given in 
Tables I and II, although not quite in the detail necessary for certain 
parts of the calculation. 
Table I. — Primary Wave. 
1 3T 
/(*>) = «/ 2- 
II 
QJ| OJ 
* 1 H 
/(*>) = «/ 2- 
Ca 
f(p) = a l 2- 
| 15-5 
0 
8 
19-9 
5*3 
48-9 
15 
2’5 
7-5 
2P5 
5-2 
49 3 
14-5 
4*15 
7 
23-2 
5*1 
49*9 
14 
5-5 
6*5 
26-5 
5*0 
50*5 
13*5 
6-7 
6*4 
355 
4-9 
51-0 
13 
7*7 
63 
36 3 
4-8 
51*9 
125 
8-7 
6-2 
37-0 
4*7 
535 
12 
9-7 
6T 
37-6 
4*6 
56-5 
1P5 
10-7 
6 0 
38-5 
4-5 
59-5-62-5 | 
11 
11*7 
59 
40-0 
4-4 
65 
10*5 
12-6 
5-8 
41-5 
4-3 
68-5 
10 
13-7 
5-7 
43-0 
4*2 
69-4 
9-5 
15-0 
5*6 
44-5 
4T 
70-5 
9 
16*5 
5*5 
47*5 
40 
71-5 
8-5 
1 
18-2 
5'4 
48-4 
The next step towards building up the integrals is to tabulate the 
values of f(p) at equal intervals dp and the corresponding values of 
— where r\ is' the lower limit of the value of p. To this end the 
values of p 2 are first tabulated in column alongside the corresponding 
