558 
GEOPHYSICS: H. F. REID 
Proc. N. a. S. 
Pacific Ocean and one passing through the West Indies, the Mediter- 
ranean, and the East Indies. These zones are the regions where sedi- 
ments were accumulated in middle geologic times, known as the Mesozoic 
Age; after consolidation into rock they have been elevated and in places 
they now form the highest mountain ranges in the world. De Mon- 
tessus de Ballore's great work need not be repeated; what is now needed 
is a detailed study of the distribution of earthquake origins in special 
regions, and this comes under our third class. 
But the distribution of earthquake centers under the seas is still in an 
embryonic state. A good beginning in the study of this problem has 
been made by Rudolph, but far more data are needed and they can only 
be supplied by the records of many widely-spread observatories. 
Much study has been given to periodic variations in earthquake ac- 
tivity and its possible relation to variations of latitude, to the positions 
of the sun and moon, to the seasons, etc. Although this line of investiga- 
tion has not yielded satisfactory conclusions and, in the opinion of some 
competent seismologists, is not destined to be fruitful, others believe in 
its possibilities. If it is to be pursued successfully it is important 
that a good catalogue of submarine earthquakes be added to the cata- 
logue of those occurring on land. There are a sufficient number of seis- 
mological observatories in the United States to supply the data required 
from this country towards the solution of these world-wide problems, 
though perhaps a new station somewhere in Texas and another in Mon- 
tana or Idaho might be of advantage. The effort should be to improve 
the stations already functioning rather than to increase their number. 
The examination of many earthquake records has convinced me that 
not a few observatories are provided with poor clocks, or that insufficient 
care is given to them. Better time-keeping will greatly increase the 
accuracy of the records. Some of the best observatories should have a 
more complete equipment. They should have seismographs of high 
magnifying powers to catch the very feeble movements, and seismo- 
graphs of low magnifying power, that the characteristics of the stronger 
movements may not be lost by too wide a range of the recording point. 
They should have instruments to record vertical motion, a component 
that has received far too little attention. I believe there are but two 
vertical component instruments in this country. 
When we consider the important area covered by the Pacific Ocean, 
we find that there are stations in Japan, Formosa, the Philippines, Aus- 
tralia, New Zealand, Chile, Panama, Mexico, California, and Sitka; 
and on the islands of Oahu, H. I., Guam, and Samoa. The last station 
was a branch of the Physical Institute of Gottingen and should not be 
allowed to fall into desuetude. A station on one of the Aleutian islands 
would also gather valuable information. 
Knott has shown that the greater part of the energy of an earthquake 
