78 H. P. Malet—On Earthquakes. 



cases, " Their characters are totally different from those of volcanic 

 phenomena," " showing the two classes of phenomena have a different 

 seat." 



There is then trustworthy evidence to show, that earthquakes do 

 not necessarily depend on volcanoes, or the contraction of the 

 mass of this globe by radiation of heat into space, or by the 

 shrinkage of the earth's exterior into the retreating nucleus ; but 

 we must briefly examine how far volcanoes may be dependent on 

 earthquakes. 



Science has not made up its mind as to the origin of these igneous 

 phenomena. The Spectator, of 5th October, 1872, discards one 

 fashionable theory thus, " It is now generally admitted that if the 

 earth really has a molten nucleus, the solid crust must nevertheless 

 be far too thick to be in any way disturbed by changes affecting the 

 liquid matter beneath." Another theory of local molten basins 

 he disposes of by saying, that " such lakes could not maintain their 

 heat for ages." It is now some years since we discarded these 

 theories in "The Interior of the Earth." The Spectator, however, 

 says, " A theory has just been put forward by the eminent seismolo- 

 gist. Mallet, which promises not merely to take place of all others, 

 but to gain a degree of acceptance, which has not been accorded to 

 any theory previously enunciated." While fully allowing the 

 position assigned to Mr. E. Mallet, and giving him full credit for 

 accuracy of observation, experiment, and calculation, we must take 

 the liberty of examining this theory so far as it is set before us. 

 It is shown " that the hotter internal portion must contract faster 

 than the relatively cool crust," and so " the shrinking of the crust 

 is competent to occasion all the known phenomena of volcanic action; " 

 '•' as the solid crust closes in upon the shrinking nucleus," the 

 crushing induces heat, and so "the access of water to such points 

 determines volcanic eruption." If by the solid crust of the earth is 

 meant a substance similar to any of the rocks we fall in with on the 

 surface, then there is no evidence to show that the crust is continuous, 

 or solid, while nothing but a continuous solid rock could meet the 

 theory. If again this is the substance alluded to, we have evidence 

 to show that the void hard rock is cooler at a depth of some 5000 

 feet, than in coal-mines at 2000 feet, so where does the supposed 

 contraction begin ? We rather think that Mr. Mallet has done more 

 to destroy the great myth of internal self-existing fire, than any one 

 of the Plutonic school has done to keep it alive. 



With these brief remarks we pass on to our little history. We 

 do not demand credence to it ; the facts are before us, always in 

 action. We only ask those who take an interest in the subject to 

 think for themselves, and, sooner or later, they will recognize the 

 picture before them. The inhabitants of volcanic regions, on hearing 

 grumblings, and feeling vibrations, say, " The mountain is in labour." 

 We all see what vast collections of matter are brought together by 

 the water drifts. We know that, season after season, materials of 

 one description are brought to the same spot, and we see on our 

 cliffs, and in our mine shafts, the thickness of these strata. We know 



