Vol. 6, 1920 . GEOPHYSICS: C. F. MARVIN 
563 
vices to minimize or ward off injuries which otherwise inevitably attend 
the great atmospheric phenomena mentioned. 
The following comprise the principal items of service: 
SUMMARY OF WEATHER BUREAU ACTIVITIES 
1. Weathbr Forecasts and Warnings 
Weather forecasts and warnings are based upon simultaneous observations of local 
weather conditions taken daily at 8 a.m. and 8 p.m., 75th Meridian time, at about 
200 regular observing stations scattered throughout the United States, and upon similar 
reports received daily from points in the West Indies, Central America, Hawaiian Islands, 
Alaska, Canada, Bermuda, and a few other parts of the Northern Hemisphere. The 
reports are received by telegraph, charted, and the forecasts and warnings deduced 
therefrom are issued from district centres located at Washington, D, C, Chicago, 
111., New Orleans, La., Denver, Colo., and San Francisco, Calif. The forecasts and 
warnings are of varying classes as follows: 
(a) Daily Forecasts and Weather Information. — These forecasts are issued twice daily 
in the a.m. and p.m. and are telegraphed to about 1,600 principal distributing points 
and thence they are further disseminated by telegraph, telephone, radio and mail to 
several thousand communities. They are furnished also to the press association and 
newspapers and are published by practically every daily newspaper in the United 
States, thus reaching all sections and every class of people. The weather observations 
on which the forecasts are based are printed in map and bulletin form and mailed or 
delivered to commercial, marine, agricultural, industrial organizations, educational 
institutions, etc. 
These maps and bulletins are prepared, printed and distributed within three hours 
after the observations are taken. 
The manifold uses to which the daily weather forecasts and weather information 
are applied are impracticable of enumeration as the life and activity of the whole popula- 
tion is more or less affected by the weather and receives more or less benefit therefrom. 
{h) Weekly Forecasts. — Forecasts are made each Saturday for the six days beginning 
with the ensuing Monday. These forecasts are made separately for nine districts 
covering the entire United States, and necessarily are couched in general terms. They 
are immediately telegraphed to certain designated centres whence they are further 
disseminated by telegraph, telephone, and mail, and are published in Sunday and Mon- 
day newspapers following the day of issue. 
These forecasts are intended more particularly for the agricultural interests, as a 
guide to their activities during the growing season; and the Weather Bureau is in re- 
ceipt of many communications testifying to their great value. 
ic) Shippers' Forecasts. — Forecasts of temperature expected within the following 
24 to 36 hours that will be injurious to perishable products in shipment are made by 
officials in charge of the stations located in large commercial centres. They are issued 
only when temperatures of 32 degrees or lower, or 90 degrees or above, are expected. 
Special distribution of these forecasts is made to railroads and shippers of perishable 
products. Shipments are to a large degree regulated by these forecasts. The saving 
affected thereby is enormous. 
{d) Storm and Hurricane Warnings. — This service consists of the issuance to shipping 
interests on the Atlantic, Pacific and Gulf coasts and in the waters adjacent thereto 
and on the Great Lakes, of warnings of the approach of storms dangerous to shipping, 
and to the coasts of the South Atlantic and Gulf States and adjacent regions of the ap- 
proach of hurricanes. These warnings are disseminated by means of flags by day and 
lanterns by night, displayed at about 425 ports. In addition, the warnings are tele- 
