June 3, 1904.] 



SCIENCE. 



845 



great climatic changes, togethex* witli many 

 related problems that enter profoundly 

 into the interpretation of the earth's past, 

 and seem to have immense importance to 

 the future of the human race. 



In reference to the waters of the earth, or 

 the hydrosphere, the geophysicists desire an 

 opportunity to investigate its origin, mass 

 and mass distribution; the constancy or 

 variations in the volume of the ocean and 

 changes in its level in relation to the land ; 

 the part which the water-mass plays in the 

 changes of the form of the earth; the 

 origin, constancy, or variation of the 

 ocean's salinity, and many other questions. 



Concerning the rigid outer portion of the 

 earth, or the lithosphere, the geophysicists 

 would seek for information relating to the 

 origin and maintenance of the continental 

 platforms with their superposed mountains 

 and plateaus, and of the oceanic basins, 

 involving questions of rigidity, distribu- 

 tion of pressures, etc.; the agencies and 

 conditions that make possible the prolonged 

 periods of crustal quiescence recorded on 

 the earth's surface by extensive plains pro- 

 duced by erosion ; the nature and causes of 

 the movements in the earth's crust which 

 have produced crumplings and breaks or 

 faults, and upraised mountains and 

 plateaus, and are indicated also in a large 

 way by continents and oceanic basins; the 

 breaking, shearing and folding of the rocks 

 leading on to the general problems of rock 

 metanaorphism, and a great group of intri- 

 cate questions of a chemical and ehemico- 

 physical nature, including the flow of 

 rocks, the destruction and genesis of min- 

 erals, the functions of included water and 

 gases, the flow of material within the earth, 

 the origin of ore deposits, the evolution and 

 absorption of heat, and other phenomena 

 that involve the effects of temperature, 

 pressure, tension and resultant distortion 

 on chemical changes and mineralogical ag- 

 gregations. 



Within the earth's outer crust lies what 

 is termed the centrosphere, concerning 

 which the advisory committee on geophysics 

 states its desires as follows: The themes 

 here are the kinds and distribution of the 

 lithic and metallic materials in the deep 

 interior; the states of the matter; the dis- 

 tribution of mass and of density and the 

 consequent distribution of pressure; the 

 origin and distribution of heat ; the conduc- 

 tivities of the interior material under the 

 pressure and heat to which it is subjected; 

 the heat possibilities arising from supposed 

 original gaseous condensation, or alter- 

 nately from initial impact of aggregation; 

 the heat of subsequent attractional con- 

 densation; the secular redistribution of 

 heat within the earth, and its loss from the 

 surface; the possible relations of redistri- 

 biition of internal heat to volcanism and to 

 deformation, and similar profound prob- 

 lems. 



Long as the above category of as yet un- 

 solved problems may seem, it by no means 

 exhausts the lines of earth study suggested 

 to the Carnegie Institution as awaiting 

 elucidation. Laboratory experiments are 

 outlined in reference to the effect of pres- 

 sure on the melting point of rocks carried 

 on at high temperatures and pressures, and 

 through a wide range of material; the 

 effect of temperature and pressure on ther- 

 mal conductivity and on elasticity, with 

 reference especially to the transmission 

 through the earth of seismic tremors. Nor 

 is this all; geophysical questions in refer- 

 ence to the relation of the earth to other 

 bodies in the solar system, such as the de- 

 formation of the earth owing to the attrac- 

 tion of the sun and moon, thus furnishing 

 a means for testing its rigidity, the history 

 of oceanic tides and their influence on the 

 earth's rotation. These and other questions 

 lead to still greater problems such as the 

 origin of the solar system and even the 

 genesis of the stars. 



