Mr Fisher, On the transmission of Earthquakes, etc. 231 
On the transmission of Earthquakes through the Earth. (Second 
paper.) By Rev. 0. Fisher, M.A., F.G.S., Hon. Fellow of Jesus 
College. 
[ Received 26 April, 1907.] 
In a paper published in the Proceedings of the Cambridge 
Philosophical Society (Vol. xii., Pt v., 1903) I endeavoured to 
explain the transmission of a world-shaking earthquake. I assumed 
the substratum of the earth’s crust to be a liquid magma holding 
water-gas in solution in accordance with Henry’s law, and attri- 
buted the primary disturbance to a sudden diminution of pressure. 
I suggested that the first phase of the record at a distant station 
might be attributed to an elastic wave propagated in the magma 
before the pressure had fallen sufficiently for the evolution of gas, 
and that the second phase might be due to a succeeding wave 
caused by the evolution of gas as the pressure fell still further. 
This theory has met with a certain amount of commendation, 
and this has led me to enquire whether the relative characteristics 
of the two phases on this hypothesis would at all agree with the 
observed facts. 
What these are is concisely shown in the subjoined diagram 
reduced from Prof. Omori’s article in Publications of the Earth- 
quake Investigation Committee, No. 13, Tokyo, 1903. 
Pendulum record of a distant earthquake (Prof. Omori). 
— mwin/\/{flJ[j j j |||^ 
“ ab, First preliminary tremor [elastic wave]. 
be, Second ,, ,, [gaseous wave]. 
edefg, Principal portion. 
j, End portion.” 
ab is the first phase, and be the second phase. These are transmitted through 
the interior of the earth, defghij are transmitted round the surface supposed by 
gravity. The end portion has not been explained. 
Consider a column of the magma 
o 
M 
4 - 
N 
4 - 
M' N' 
O' 1 1 ' 
Let 0 M = x in the undisturbed state. Since the disturbance 
at the origin is supposed to consist in a fall of pressure, when the 
