SOLAR VARIATION AND WEATHER—ABBOT 153 
However, if one were content with 5- or 7-year predictions, such 
shifts of phase could be corrected from time to time. 
CONCLUSION 
I have brought together many evidences which seem to indicate 
that the small percentage changes observed in the solar emission of 
radiation are effective factors in the domain of weather. Many others 
have been published by H. H. Clayton. The solar measurements in- 
volved are exceedingly difficult and require installations on high moun- 
tains in desert regions, where the largest percentages of clear skies 
with low wind velocities prevail. Three stations maintained by the 
Smithsonian Institution are now engaged in day-to-day measure- 
ments of the solar constant of radiation. On account of the variable 
obstruction occasioned by the atmosphere, laden as it is with clouds, 
dust, ozone, and water vapor, these three stations are insufficient 
adequately to follow and record the sun’s variation. About three 
times as many mountain stations, widely separated in the most cloud- 
less and calm regions of the earth are needed. They could be installed 
for $500,000, and operated for $250,000 per annum.® 
I think there is a great probability that if such additional solar 
stations were in operation they would furnish information of major 
value to meteorology. I believe that with the solar data that would 
then be available, and using the rich store of information regarding 
terrestrial factors now familiar to meteorologists, great progress 
would ensue. The neglect of solar variation, which seems to be a 
major factor in weather, cannot continue if meteorology is to progress 
as it should. It would be like the play “Hamlet” with Hamlet’s part 
omitted. 
€ Very recent developments of the research, however, give hope that another approach 
to the problem not requiring additional stations may be successful. 
