94 
ASTRONOMY: C. G. ABBOT 
Proc. N. a. S. 
at Mt. Wilson affect terrestrial temperatures to a considerable extent and 
also induce variations of terrestrial atmospheric pressure. Mr. Clayton's 
investigations have led him to the conclusion that the tropical and the 
polar regions of the earth are made warmer by temporary increases of 
solar radiation, while the temperate regions both north and south of the 
equator are made cooler by the same increase of radiation. Dr. Nansen, 
however, is of the opinion that when more thorough studies of the matter 
have been made, it will be found that the effects are not thus zonal, but 
rather are associated with the great action centers of atmospheric circula- 
tion. Dr. Nansen's view is that since a considerable portion of the sun's 
radiation is absorbed by the clouds, dust and water vapor in the atmos- 
phere, a change in the amount of solar radiation may produce notable 
changes in the atmospheric circulation, and these, by altering the direction 
of the prevailing winds, may alter indirectly the temperature of meteoro- 
logical stations. Hitherto the amount of investigation of the variation 
of the sun has been inadequate to give very satisfactory data to work with 
in determining these correlations. The present expedition of the Smith- 
sonian Institution to Chile, it is hoped, will be continued for several 
years and will enable meteorologists to trace this relation much more 
thoroughly. Mr. Clayton, from the studies he has made and is making, 
is very sanguine about the value of solar radiation observations such as 
are being made by the Smithsonian observers. 
The accompanying illustration, prepared from Clayton's studies, shows 
the remarkable courses of temperature departures at Buenos Aires, fol- 
lowing high, intermediate and low values of the solar constant of radiation. 
A very great deal of additional statistical inquiry is already possible 
in view of the series of solar constant observations reported by the Smith- 
sonian observers on Mt. Wilson. There is now a much more continuous 
series of results available extending from July 27, 1918, as obtained at 
Calama, Chile. Meteorologists should be in a position to study these 
observations in connection with the temperature, pressure, cloudiness 
and wind at a very great number of stations distributed as well as possible 
over the earth's surface. It is only by such laborious investigation 
that a sound basis can be laid for the improvements in forecasting which 
Mr. Clayton thinks are now possible. 
If it shall appear from such statistical investigations that the varia- 
tions of the sun are really important for forecasting purposes, and if 
it shall prove possible to establish three or four additional solar radia- 
tion stations, widely scattered in the most cloudless regions in the world, 
then we may contemplate the possibility that from each such solar radia- 
tion station the results of each day might be sent out by wireless telegraphy, 
to be employed by the meteorological stations of the different countries 
for forecasting purposes. Experience in Calama, Chile, indicates that 
with a staff of three industrious and energetic persons it is possible to 
