568 
GEOPHYSICS: C. F. MARVIN 
Proc. N. a. S. 
effects on the development of vegetation and farm activities in general. In addition, 
the Bulletin contains from time to time charts and discussions bearing on the relation 
of climate to crops and agricultural operations. 
The value of this publication is evidenced by the popular demand for it, which has 
grown to such proportions as to severely tax the printing facilities of the Bureau. There 
are about nine hundred paid subscriptions to this publication and about twenty-seven 
hundred other recipients. 
In addition, a weather and crop summary is issued during the active agricultural 
season at each state center, forty-two in number, which is disseminated by bulletins 
and through the public press. 
These services are of much value to those interested in agricultural operations through- 
out the country, as they afford detailed information as to the prevailing weather in 
all sections and its effect on farming operations and crop development, 
(b) Corn and Wheat Service. — This service is maintained during the active growing 
season of each year, April 1 to September 30, in sixteen principal grain states. Daily 
weather reports are received from one hundred and eighty-seven special reporting sta- 
tions. Daily bulletins are issued from nineteen points. A weekly corn and wheat 
region bulletin is issued also at the regional center, Chicago, 111, 
This service is of especial benefit to farmers, dealers, millers and others interested 
in the cereal crops of the United States, and gives accurate information as to prevail- 
ing weather conditions throughout the principal producing areas during the period of 
crop development. There are constant and persistent demands for extensions of the 
service into regions not now covered, 
(c) Cotton Region Service. — This service is similar in organization and operation to 
the corn and wheat region service, and covers the cotton growing states of the country. 
About two hundred reporting stations are maintained. Bulletins are issued from 26 
stations located in the cotton belt. The service is maintained in the interest of cotton 
growers and others engaged in various lines connected with the industry. It is con- 
sidered by cotton growers and dealers to be of indispensable value. 
(d) Cattle Region Service. — This service is maintained for the collection and dissem- 
ination of information of current weather conditions over the great grazing districts 
of the west and southwest as affecting the stock industry. Weekly bulletins are issued 
from a number of central points throughout the year, giving information as to rainfall, 
temperature, snowfall, and general grazing conditions on the ranges. 
10. SoivAR Radiation Investigations 
The importance of sunshine as a weather and climatological factor is fully recognized 
by meteorologists, climatologists, biologists and others. Until a comparatively recent 
time, only the duration of sunshine has been recorded. The object of the solar radia- 
tion investigations is to measure the intensity of the sun. These data have not only 
direct application to agriculture, but have a value in many other ways. Illuminating 
engineers have for a long time been asking for measurements of daylight or sunshine 
intensity expressed in light units. This information is of special value to them in con- 
nection with the designing of factories and other buildings to meet the requirements 
of state laws relative to natural light. 
11, SeismoIvOgicaIv Investigations 
The object of these investigations is to determine how frequently on the average 
and how severely the various portions of the country are shaken by earthquakes. 
From the data thus collected, it is determined what sections of the country are seismic; 
just where the active cracks are, and their liability to further slips or movements. 
This information is of prime importance in enabling engineers to avoid the placing of 
aqueducts for city water supplies, dams and other structures on or across fault lines. 
