OUR PRESENT KNOWLEDGE OF ISOSTASY 445 



191 7 formula there were 358 stations used, 216 of which were in the 

 United States. 



There was not available for the foreign stations such detailed 

 information as was available for the stations in the United States, 

 and it was therefore not possible to utilize the foreign stations in 

 making certain tests, but the geodetic evidence available for the 

 foreign stations makes it practically certain that isostasy is in as 

 nearly a perfect state in those countries as it is in the United 

 States. 



There is no geodetic evidence disclosing the process by which 

 the isostatic adjustment takes place. This is a matter for specula- 

 tion rather than proof. 



The subject of isostasy is a very important one and a very broad 

 one, and the work that has already been done is very small in com- 

 parison with what must be done in order to discover the laws of 

 the distribution of compensation, the extent to which it is perfect, 

 and the cause of the unexplained deflections of the vertical and the 

 anomalies of gravity. The field is broad, and it is necessary that 

 other scientists than geodesists should enter it. It is especially 

 desirable that geologists and geophysicists assist in the investigation. 



