meunier: theory of volcanoes 645 



bution along one and the same terrestrial radius, under the com- 

 plications that would arise from the fact of the freezing of water 

 at the surface and also at greater and greater depths. We should 

 also have to make the same inquiry as regards the distribution 

 of the water soaking into the deep strata, which would neces- 

 sarily carry with it the zone of volcanic activity. All these 

 subjects, and various other subjects besides, suggest discussions, 

 some of which promise definite conclusions. It may suffice here 

 to suggest them, while awaiting fuller data from the progress of 

 science. We can merely attempt to set up a few hypotheses 

 as regards the future of eruptive activity. 



First of all, we may turn our attention to the relations be- 

 tween the cooling process and the stock of infiltrated water. 

 The quantity of water available in the superficial regions of the 

 earth is evidently limited, and the progress of cooling constantly 

 tends to diminish the amount of water in seas, lakes, air, and 

 even in the interstices of rocks. The tentative estimates made 

 on this point at various times, by totally different methods, 

 have invariably led to the conclusion that the quantity of water 

 already absorbed by the crust is several times larger than the 

 total volume of water still remaining on the surface in the liquid 

 state; and that this remainder is only a small fraction of the 

 amount that would be needed to saturate the entire crust to the 

 degree of humidity observed in moist rocks, described by the 

 expressive term of quarry-water. A time will come, therefore, 

 when the earth will be completely dried up, because all its water 

 will have disappeared, by infiltration, in the beds of rock. 



On the other hand the globe, growing cooler all the time, will 

 some day arrive at a state of equilibrium with the temperature 

 of space. Thus the two factors of volcanism will disappear 

 independently of each other, and not necessarily at one and the 

 same time. 



Several suppositions may be based on this consideration. 

 Suppose, first of all, that the time necessary for the complete 

 absorption of the water by the crust is exactly equal to the time 

 required for the complete cooling of the globe. In that case it 

 may be that the volcanic phenomenon may gradually fade away 



