178 SEE— FURTHER RESEARCHES ON [ApnU4, 



limit of resolution of the microscope which has been estimated by 

 Michelson at 1/100,000 of an inch. 



Now in our discussion of the constitution of granites we found 

 that the visible pores in the quartz matrix have all diameters down 

 to less than 1/10,000 of an inch, and thus practically to the lowest 

 limit visible in the microscope. These visible pores thus evidently 

 connect directly with the smaller invisible spaces which separate the 

 m.olecules. As the diameters of the molecules in water vapor are 

 only about 1/5,000 of the spaces between them, the triple atom of 

 hydrogen and oxygen constituting water or water vapor would have 

 ample facilities for penetrating a spongy and cavernous mass like 

 granite with innumerable holes frequently of large size but always 

 at least equal to the average free path. If the water or vapor 

 were under pressure, so as to condense the fluid and thus increase the 

 number of vibrations of a molecule per second, the rate of penetra- 

 tion of the fluid obviously would be much augmented. 



And since granite not only is filled with pores of these various 

 sizes, but also everywhere more or less cleft by planes of crystalline 

 structures which are not really tight, but full of fissures and thus 

 inviting the penetration of the fluid by the full power of capillary 

 forces, we see that water would necessarily penetrate it at a fairly 

 rapid rate. At the same time the influence of capillarity in such a 

 structure is so great that although water might enter and slowly pass 

 through it, even the development of steam pressure beneath the 

 layer would not force the fluid back, because the steam pressure is 

 nullified an infinitely small distance from where it is exerted, on 

 account of capillary resistance ; yet the fluid may keep on descending 

 under the suction of the capillary forces so long as the supply from 

 above is not cut ofi^. 



Upon these physical grounds it seems clear that there must be a 

 secular leakage of the ocean bottoms, and a corresponding develop- 

 ment of steam beneath the earth's crust. The steam expands the 

 rock in which it is absorbed and in seeking release thus brings on 

 earthquakes and mountain formation. 



Even if the pressure due to depth should tighten up the struc- 

 ture of the rock in the lower layers of the crust, it would not be 

 able to obliterate the leakage depending on the pores and crystalline 



