64 CARNEGIE INSTITUTION 



ditions under which the component parts of the earth form and have 

 been formed. High "temperatures and pressures will therefore be 

 called upon at once. Physics is, no doubt, still far removed from 

 meeting all the needs of geology in this direction. Even though 

 3,000 atmospheres and 3,000 degress Celsius represent imposing fig- 

 ures, and these magnitudes not only can be reached, but are alread}^ 

 or in the immediate future will be measurable, in the combination 

 of pressure and temperature, we must be content at first with more 

 modest dimensions. But we shall certainly be indebted for advances 

 in these problems to just the very stimulus arising from geophysical 

 investigations. Klectrical methods of heating and of temperature 

 measurements are of very recent date and are still capable of much 

 further extension. Bolometrical, and especially optical methods of 

 pyrometr)^ also promise important developments. 



But even with the present limitations elasticity and rigidity, 

 plasticity, melting points and their dependence upon psessure, 

 vapor tension, critical temperature and the chemical relations, 

 especiall}'- to water and carbonic acid, offer fields of apparently un- 

 limited scope where as yet little has been done. Mutual solubility 

 and crystallization form solutions, i. e., the separation of magmas 

 into their component parts, are already within the reach of com- 

 paratively simple resources, and will certainly lead to most impor- 

 tant results. 



Electrolysis, which, having been cumulatively in operation for 

 thousands of 5^ears, and must have been an effective force in the for- 

 mation of the earth, still remains an entirely virgin field from a geo- 

 logical standpoint. Thermoelectric and other electrical potentials 

 and the currents developed in the body of the earth by them, can 

 scarcel}'' be said to have been studied with reference to geological 

 questions. 



Magnetism, the measure of the earth's attraction, glaciers, 

 and seismometry are probably already provided for in existing 

 bureaus of the United States Government, and consequently need 

 not be drawn upon to furnish a field for a geophysical institute. 



For these reasons I must, therefore, agree entirely with your 

 opinion, sir, that : 



' ' The time seems ripe for the attempt and it would appear that 

 success must be attended by most notable contributions to pure 

 science, as well as to the history of this planet." 

 With the highest respect, 



O. KOHLRAUSCH, 



President, Physikalisch-technische Reichsanstalt. 



