290 SEE— THE CAUSE OF EARTHQUAKES. [October 19, 



several rates of leakage for the corresponding areas of the bottom 

 of the sea. In general it is obvious that the leakage will be most 

 rapid where the sea bottom is fractured or porous, the underlying 

 temperature high, and the depth very great. A rapid rate of leakage 

 would imply that large quantities of water quickly come in contact 

 with the heated rock and develop correspondingly great steam pres- 

 sure in the crust which underlies that part of the ocean. Tait's 

 remark about the rapid passage of gases through hot steel ob- 

 viously applies to the absorption and diffusion of steam in hot 

 rock ; for this is found by experiment to be quite general for many 

 of the metals. And in the case of lava as it pours from a volcano, 

 it is observed that the molten rock emits vast quantities of vapor, 

 of which, according to Sir Archibald Geikie, 999 parts in 1,000 is 

 steam. This fact in itself is extremely impressive ; for it indicates 

 that the remaining thousandth part of the gases emitted, including 

 vapors of sulphur, hydrogen sulphide, hydrochloric and carbonic 

 acid, are derived from the rocks of the earth's crust under the action 

 of steam and the high temperature. We may therefore consider that 

 steam is the only original vapor operating in the crust of the earth. 



§ 6. Danbree^s experiments on the effects of capillarity. 



After this paper was fully outlined and some references were 

 being verified, the author had the good fortune to notice the fol- 

 lowing significant statement in Sir Archibald Geikie's admirable 

 " Text Book of Geology," fourth edition, 1903, p. 354: • 



"An obvious objection to this explanation is the difficulty of conceiving 

 that water should descend at all against the expansive force within. But 

 Daubree's experiments have shown that, owing to capillarity, water may 

 permeate rocks against a high counter pressure of steam on the further side, 

 and that so long as the water is supplied, whether by minute fissures or 

 through pores of the rocks, it may, under pressure of its own superincumbent 

 column, make its way to highly heated regions. Experience in deep mines 

 rather goes to show that the permeation of water through the pores of the 

 rocks gets feebler as we descend." 



In his *' Physics of the Earth's Crust," second edition, p. 144, Rev. 

 O. Fisher also makes some interesting remarks on Daubree's ex- 

 periments, which are included in his " Rapport sur les progres de 

 la Geologic experimentale," Paris, 1867. After describing Daubree's 

 experiment, Rev. Fisher remarks : 



