FUTURE HABITABILITY OF THE EAETH CHAMBEELIISr. 385 



The feature of profoimdest importance from our racial point of 

 view, the maintenance of tlie land against the incessant encroachments 

 of the sea, seems to be assignable to internal agencies which at peri- 

 odic intervals bring about a deformation of the earth's body and a 

 readjustment of the waters on its surface to the changed capacities of 

 its basins. These actions involve changes also in the contact of the 

 air with the earth substance which increases or diminishes the con- 

 sumption of the air by chemical combination. At the same time, 

 these deformations are probably related to volcanic and other ex- 

 trusive actions which feed the atmosphere. How far this volcanic 

 feeding is merely a return to the air of what had been absorbed 

 earlier it may not be safe here to say, as opinion is not yet at one 

 on this point, though the force of growing evidence seems to imply 

 that at least a notable part of the volcanic gases are original. Final 

 opinion on this' point is dependent on what views shall ultimately 

 prevail respecting the conditions in the interior of the earth, and 

 these in turn are much dependent on the mode of origin of the earth. 

 Perhaps it will be generally agreed that feeding from the interior is 

 one of the sources of atmospheric supply, and that it helps to offset 

 the depletion caused by chemical union with the earth substance ; in 

 other words, that the earth body gives out as well as takes in at- 

 mospheric material. It is not apparent, however, that there is any 

 special automatic balancing of these opposite processes, such as ap- 

 pears to be requisite for maintaining the delicate adjustment on which 

 the secular continuity of life depends. 



The ocean acts as a regulator of the atmosphere by alternately 

 absorbing into itself and giving out atmosj^heric gases under the 

 control of the equilibrium that exists between the gases in the water 

 and in the air. This action is automatic and appears to be important. 

 It has, however, its peculiarities and its limitations, and it does not 

 seem to be wholly adequate, even when added to the preceding 

 agencies. 



If it is possible at the present stage of inquiry to point to an addi- 

 tional automatic action that promises to supplement the preceding 

 in such a way as to make up a competent regulative mechanism, 

 it seems to me most likely to lie in the high speed necessarily attained 

 by some of the molecules of all atmospheres which causes them 

 to escape from the gravity of the body about which they are gathered 

 and to fly off into the sphere of control of some adjacent body, thus 

 giving rise to an interchange of atmospheric matter. It seems safe 

 to affirm that such interchanges prevail, but it remains to learn how 

 effective these interchanges may be. The results of personal inquiries 

 that have been in progress for some time have not yet been submitted 

 to the full criticism of those best qualified to test them, and they can 

 97578°— SM 1910 25 



