Vol. 6, 1920 
GEOPHYSICS: H. F. REID 
555 
show the relation of forces to movements of material, the origin of forces, 
and their causes. It would really combine the subjects of isostasy, earth 
tides, variation of latitude, seismology, and certain phases of volcanology. 
The data collected in those branches of geophysics should be considered 
in connection with geology in order to interpret in the light of present 
knowledge the various movements that have taken place in the earth. 
Up to this time, it is believed that these data have not been given due 
consideration and weight in the study of the earth, its structure, forces, 
etc. 
Some of the subjects that have been discussed above are only inci- 
dentally related to geodesy, but the results of investigations in them are 
certainly of great value and interest to geodesists and it is believed that 
there should be committees of the Section of Geodesy of the American 
Geophysical Union to consider these questions and be able to inform the 
members of the Section at any time as to the progress made in these 
branches of geophysics. There are several of the subjects which have 
sections of their own, for instance, those of Seismology and of 
Volcanology. 
The Geodetic Section of the American Geophysical Union will not at- 
tempt, nor does it desire, to pre-empt any field of geophysics nor will it 
encroach on the rights and privileges of any other organization. It will 
simply attempt to keep informed of what is going on in the various fields 
of geophysics which are of interest to geodesists and it hopes that it 
may from time to time give some assistance to other organizations in 
suggesting problems or lines of research. On the other hand, it stands 
ready to receive suggestions and help from any other organization dealing 
in any branch of geophysics. 
1 Bulletin of the Phila. Soc. of Washington, 1 1 (51-64). 
2 Supplemental Investigations of the Figure of the Earth and Isostasy from Measure- 
ments in the United States, 
THE PROBLEMS OF SEISMOLOGY 
By Harry Fielding Rbid 
Although earthquakes have received sporadic attention for some time 
in the past, their systematic study may almost be said to have begun with 
Mallet about the middle of the last century; and it was only towards 
the end of the century that instruments delicate enough to register dis- 
tinct shocks were developed, making it possible to gain some knowledge 
of the characteristics of earthquake vibrations and the velocities wich 
which they are propagated through the earth. But, notwithstanding 
the shortness of the time during which these studies have been in progress, 
the science has been well outlined and first approximations to the solutions 
of many of its problems have been obtained. The time has now arrived 
