6 CARNEGIE INSTITUTION OF WASHINGTON. 



Among other significant contributions recorded, it should be noted 

 that in three of the subjects in which cooperative work was undertaken 

 additions to knowledge have been made which rank as epoch-making 

 in these fields. The work of the Coast and Geodetic Survey in 

 demonstrating horizontal movements of the earth's crust, amounting 

 to many feet over a considerable part of California, opens a new field 

 not only for seismology and geology but also for geography. In 

 mapping the floor of the Pacific Ocean off the southern coast of Cali- 

 fornia out to the 2,000-fathom line, by use of the sonic depth-finder 

 or the "echo" method, the Hydrographic Office of the United States 

 Navy opened a new chapter in study of the sea. The construction 

 of a new but extremely simple and effective seismograph by Dr. 

 Anderson, of Mount Wilson Observatory, clears the way for new 

 researches in the history of earthquake phenomena having special refer- 

 ence to definite lines of fracture in the earth's crust. 



In addition to the previously planned investigations into the nature 

 and effect of earthquakes the generosity of the Carnegie Corporation 

 of New York at a critical moment made it possible to send a repre- 

 sentative of the Institution to Chile for the purpose of studying 

 problems arising out of the earthquake of November 1922. Dr. 

 Bailey Willis, who undertook this work, received most cordial support 

 and every possible assistance from the Government of Chile and 

 from its representatives in all departments. The results of this 

 study have given us a valuable interpretation of movements of 

 the crust of the earth in Chile involving origin and growth of the 

 Andes Mountains. In addition to the fundamental researches in 

 seismology. Dr. Willis gave special attention to interpretation of 

 earthquake phenomena in terms of the engineering phase of building 

 construction considered with special reference to immediate needs of 

 the people of Chile. 



In the Department of Terrestrial Magnetism another kind of in- 

 vestigation involves the phenomena of magnetism, electricity, and 



gravity as expressed in our earth as a unit. Con- 

 Ma^netSm sideration of these aspects of the earth relates itself 



on the one hand to problems of astronomy and on 

 the other side to questions arising in the Geophysical Laboratory. 

 Although the method of approach in this study of the physics of the 

 earth is widely different from that in the special fields of our other 

 great laboratories, it is inevitable that in final consideration of the 

 data secured the results will in considerable measure assist in explana- 

 tion of phenomena examined by other investigators. 



