30 CARNEGIE INSTITUTION 



of geology, geophysics and astronom5^ Among its sailent questions 

 are those of its origin , its mass, its mass-limitations, its mass-distribu- 

 tion, the potential atmosphere absorbed in the ocean and in the body 

 of the earth, its sources of depletion and enrichment, the constancy 

 or fluctuation of its volume and of its constituents, its function as 

 a thermal blanket, the possible changes in its diathermac)^ and the 

 relations of these to great climatic chances, together with many 

 related problems that enter profoundly into the interpretations of the 

 earth's past, and seem to have immense importance to the future of 

 our race. 



In these problems of the atmosphere, the hydrosphere participates. 

 It also presents questions of its own as to its origin, mass and mass- 

 distribution ; the constancy or variation of the volume of the ocean ; 

 the possible function of the waters in promoting their own seggre- 

 gation and the relation of this to the extension and withdrawal of 

 the ocean relative to the land ; the part which the water-mass plays 

 in the changes of form of the earth ; the origin, constancy, or vari- 

 ation of the ocean's salinity, the significance of this in past and 

 future histor}^ and many other questions. 



The solution of nearly all of these problems rests ultimately upon 

 grounds that need the searching tests of the laboratory. For ex- 

 ample, a rigorous determination of the diathermacy of the air, and 

 of its dependence on the several atmospheric constituents, and on 

 their relations to each other, their ionization, their nucleation and 

 their other states, is just now most urgentl}^ needed. So is also a 

 critical inquirj'- into the part the ocean is competent to play in ab- 

 sorbing and giving forth atmospheric constituents under different 

 conditions of temperature, pressure, tension, salinity and biological 

 content. 



2. The crust of the lithosphere has thus far been the chief field 

 of geology- in the narrower sense, since it contains the rock record 

 of the earth's past, and geological studies have peen directed chiefly 

 to reading and mapping this record. But the record needs to be 

 interpreted on broader and deeper lines, based on a profounder 

 knowledge of physical laws. To this end the data of geology need 

 to be correlated and unified under these laws on an experimental 

 basis. Apart from the record in the layers of sediment, there is a 

 recondite but less legible record in the dynamic features of the 

 earth, and to read these successfully will require the utmost re- 

 sources of research, involving the fullest available aid of geodetic, 

 ph^^sico-chemical and mathematico-physical investigation. 



