394 CARNEGIE INSTITUTION OF WASHINGTON. 



of a new instrument for the purpose which is capable of attaining to an 

 accuracy of one part in a million and is light enough to be carried about by 

 hand. Such an instrument would permit determinations at a great number 

 of places and would not be limited in use to places of easy accessibility as now. 

 Such an instrument in the hands of the U. S. Coast and Geodetic Survey would 

 soon provide a tangible connection between the gravitational anomalies which 

 are everywhere found in the West Coast region, and the physical structure 

 and distribution of density in the Earth's crust. 



The design of a more appropriate instrument has been undertaken by the 

 Geophysical Laboratory of tbe Carnegie Institution with the cooperation of 

 the Coast and Geodetic Survey. 



It is not possible within the limitations of an administrative report to give 

 details, even essential ones, of so comprehensive a program, but a very 

 strong group of institutions has been brought together here with the single 

 purpose of elucidating tbe problem of the California earth movements from 

 every practicable viewpoint. It is a problem of equal importance to the 

 science of seismology and to the economic life of one of the most active and 

 prosperous regions of the United States. Your committee, therefore, earnestly 

 recommends the continuance of the support hitherto given to the organiza- 

 tion which has been effected, together with appropriate provision for the con- 

 struction of additional instruments, as soon as the new designs shall have 

 proved effective and stations are established for their installation and continu- 

 ous service. 



It is further recommended that Mr. H. O. Wood, Research Associate in 

 Seismology, be continued in charge of the field reconnaissance and any 

 seismograph stations that may be established. 



J. A. ANDERSON, 

 RALPH ARNOLD, 

 W. W. CAMPBELL, 

 ARTHUR L. DAY (Chairman), 

 A. C. LAWSON, 

 R. A. MILLIKAN, 

 HARRY FIELDING REID, 

 BAILEY WILLIS, 



Advisory Committee in Seismology. 

 Carnegie Institution op Washington, 



September 1922. 



