DETERMINATION OF EPICENTRE AND FOCUS 71 
crepancies of as much as 2 seconds. These may be quite real, 
for it is not unlikely that the velocity may differ sufficiently in 
different directions to account for this. 
Station. A. Jey Station. A. 1B 
km. leer iy km. Ine, Se. 
Biberach . . 39 2I 25 59 | Aachen 36252 2One a2 
Karlsruhe . IOI 26 867: | Gottingen 362 42 
Zurich I2T to | Bochum . 385 45 
Strassburg 123 to | Triest 446 55 
Heidelberg 130 12 | Laibach . 463 58 
Jugenheim 169 18 | Graz 474 DG Tt 
Frankfurt . 222 22 | Wien 510 6 | 
Neuchatel 233 23 | Agram 571 8 
Krakau 793 42 
From the simpler theoretical table we get the following 
times to the nearest second. 
by To from the data. 
hk =1.km.|h=10.km.| kh =40.km. | #=1.km. | 4= 10. km. h = 40. km. 
km. s. s s hemes) | ha sms Ss. h. m. s. 
39 6 6 8 21 25 53 |- 20 25 53] 25 25) 52 
| tor ce 14 15 53 55) 52 
| 122 17 17 18 53 53 52 
| 130 18 138 19 54 54 53 
| 169 24 24 24°5 54 54 53°5 
The conclusion is that % was not as great as 4o km. and 
that 10 km. is better, but on the data we can hardly say that 
h might not have been zero. | 
What seems to be clear is that unless the times were 
known to o'1 second, only observations at less than 50 km 
would be of value to settle the matter. From a human point 
of view one hopes that no such case will ever occur, and the 
problem of finding the depth of the focus is more likely to be 
solved by direct observation of the emergence angle with 
horizontal and vertical seismographs combined. 
