28 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1917. 



vations at all times of the year may be obtained for use in such 

 meteorological researches. It was for this purpose that the South 

 American expedition was planned, and it will be unfortunate, indeed, 

 if war conditions should long delay the carrying out of this work. 



POSSIBILITY OF FORECASTING FROM SOLAR OBSERVATIONS. 



As Doctor Clayton has shown that variations of the sun are fol- 

 lowed a day or two later by correlated variations of temperature, it is 

 of interest to inquire if the fluctuations of temperature thus caused 

 are large enough to be worth predicting. From Clayton's curves it 

 seems to be shown that in 1913 and 1914 changes of solar radiation 

 of 1 per cent produced changes of maximum temperatures as follows : 



Pilar, Argentina, +5.2° C. 



Manila, Philippine Islands, +1.5° C. 

 Winnipeg, Canada, —6.3° C. 



It may be supposed that the mean temperatures changed half as 

 much, or +2.6°, +0.75°, and —3.15° corresponding to 1 per cent 

 rise of solar radiation. Changes of 3 per cent or even 5 per cent in 

 solar radiation within 10 days are not very uncommon. For instance 

 note the following values of "solar constant" observed on Mount 

 Wilson in 1911 : 



Date, Sept. 3456789 10 11 



A^alue 1.888 1.906 1.917 1.960 1,938 1.993 1.948 1.908 1.892 



The observed range was 5.5 per cent in 8 days. 



Obviously, the subject presents possibilities that when sufficient 

 observing stations are equipped in various cloudless regions to yield 

 accurate "solar constant" values every day, it may be possible to 

 forecast for one or two days in advance a very considerable part 

 of the now outstanding temperature fluctuations. At present the 

 two stations of the Smithsonian Institution in California and North 

 Carolina are the only ones making the required solar observations, 

 and not in half of the days in the year, especially in midwinter 

 and midsummer, can observations be made on account of cloudiness. 

 A bequest of $500,000 would emable the Institution to equip and 

 maintain indefinitely the required observing stations. 



INTERNATIONAL CATALOGUE OF SCIENTIFIC LITERA- 

 TURE. 



As the greater part of the countries supporting regional bureaus 

 of the International Catalogue of Scientific Literature are now actu- 

 ally engaged in hostilities, a great deal of difficulty has been encoun- 



