164 SEE— FURTHER RESEARCHES ON [April 24, 



the historical period. The seismic sea waves following the earth- 

 quakes which affect this region indicate that the sea bottom often 

 sinks after these disturbances. In other words, when lava is ex- 

 pelled from under the trench and pushed under the adjacent ridge, 

 the bottom gives down to secure stability. The processes now 

 going on have been at work through immense ages, and have thus 

 dug out the trough parallel to the Aleutian Islands, and at the same 

 time elevated this ridge, till it is now partly above the water, thus 

 constituting the chain of islands. 



In like manner the great earthquake at Yakutat Bay, farther 

 east, September 3-20, 1899, which was so carefully investigated by 

 Tarr and Martin (Bulletin of the Geological Society of America, 

 May, 1906) raised the coast for about 100 miles ; the maximum 

 elevation being 47^ feet. Subsidence also occurred in a few places. 

 Such a vast movement of the coast indicates an enormous expulsion 

 of molten rock from beneath the sea under the land. It is these sub- 

 terranean movements beneath the earth's crust which shake down 

 cities and devastate whole countries. During the earthquake at 

 Yakutat Bay the shaking was so terrible that persons could not 

 stand on their feet ; avalanches slid down the mountains, and gla- 

 ciers were carried into the sea. This is the true nature of earth- 

 quakes, and one need not therefore be surprised at the devastation 

 produced. The force which pushes lava under the land, overcoming 

 the weight of the crust, naturally destroys cities and all the frail 

 works of man built upon the surface. 



§ 4. Physical Experiments on the Porosity of Matter. — Modern 

 science presents many illustrations of the porosity of matter. In 

 fact so many experiments illustrate porosity that it is difficult to 

 find proof of the general property of impenetrability cited by New- 

 ton in the " Principia," except under the narrow limitations that 

 the matter in question remains cold and the forces to which it is 

 subjected are small. With increasing fluid pressure and rising 

 temperature all matter is leaky ; and in general a rise of temperature 

 expands and thus augments the penetrability and porosity of all sub- 

 stances. We max therefore say that all matter is porous and leaky 

 under great fluid pressure, and impenetrability does not exist except 



