Phillips. — On the Volcanoes of the Pacific. 521 



that this globe will not support human life, in consequence of 

 the absence of surface-water, which has been absorbed by the 

 planet itself. Even granite requires a certain amount of 

 water to preserve its crystallization. I should therefore con- 

 clude that there is water still in the body of our moon, but no 

 surface-water, and that the volcanoes there are all extinct. 



The phenomena of the earth-wave attending earthquakes 

 can perhaps be seen by the following simple experiment : 

 Take a couple of milk-dishes ; stand one inside the other, but 

 separate the two with three small blocks of wood ; pour into 

 the top dish a bucket of milk, fresh from the cow ; let it 

 stand for a couple of hours, until the cream is fairly rising ; 

 then into the lower dish pour a bucket of boiling water : this 

 will have the effect of altering the temperature of the milk, 

 causing the cream to form into a skin on the top of the milk, 

 and beneath this skin the imprisoned heat-waves in the milk 

 will fairly exemplify the earth-waves during an earthquake. 

 The cream-skin moves up and down as the imprisoned heat 

 below" endeavours to find vent, but it never moves lengthwavs. 

 The circular motion of" the ground in an earthquake, too, can 

 be noticed in the cream-skin as the heat-bubbles rise through 

 the milk. We can see — (1) The upward thrust ; (2) the wave 

 motion ; (3) the side-to-side motion ; and (4) the circular 

 motion experienced during an earthquake fairly exemplified 

 in this simple experiment. The rapidity with which the 

 waves beneath the skin or crust move across the pan is only 

 an instance of the velocity of motion, whether in light, heat, 

 or sound. The wave travels under the sea just as readily as 

 in the milk-pan, forming the tidal w^ave. 



Mr. Napier Bell tells me that to account for the tidal wave 

 he suspended a milk-pan, filled it with water, and then sharply 

 struck the side. But this did not carry the wave as he ex- 

 pected. (If he tries heating the milk he will see the waves 

 readily and quickly following each other.) The cream-skin, 

 if as rigid as our earth's crust, would, I suppose, crack as the 

 waves pass beneath it. Now, as all the great volcanoes are 

 close to or in the sea, it is evident that sea-water pouring 

 through the earth's crevices — of which there are many every- 

 where — reaching the central heat, is there converted into 

 steam, which, becoming highly heated and imprisoned, seeks 

 an outlet in waves along the crust of the earth, just as the 

 heated milk moves beneath its cream-skin. I have noticed, 

 also, that brine in which meat has been cured, after boihng, 

 and w'hen cooling, shows movements similar, I expect, to 

 those observed in boiling-lava streams. 



From Mounts Erebus and Terror in the Antarctic to 

 Mount Heela in Iceland, around and through the Pacific 

 Ocean, and towards the Mediterranean and elsewhere, there 



