240 proceedings: Washington academy 



atmospheric transmission. Third, I am not convinced of the conclu- 

 siveness of Mr. Clayton's methods of analysis of the data employed. 



In conclusion, I wish to make it very clear that my skepticism is 

 not in the slightest degree directed against the work of the Astro- 

 physical Observatory. Dr. Abbot's work should be supported and 

 extended in the fullest possible manner purely on its own merits and on 

 account of the importance of observations of intensity of solar radia- 

 tion to general meteorology. For example, I wish we might have, and 

 I am ready to recommend urgently that we have, say 12 stations, 

 maintained throughout the world. These should be located as nearly 

 as possible in four groups of three each, the three located on the same 

 meridian of longitude, the four groups separated by approximately 90° 

 of longitude. Such a system of stations would make possible simul- 

 taneous measurements of intensity every six hours. This proposal is 

 submitted largely as a scientific desideratum. It is recognized that 

 geographical and meteorological conditions operate in a very material 

 way as obstacles to its complete realization. 



Dr. W. J. Humphreys, of the Weather Bureau, said that it is now 

 quite certain that the sun is a variable star. Explosions, or something 

 analogous thereto, cause spots in the sun, and naturally lead us to 

 expect variability in its radiation such as is actually found in Dr. 

 Abbot's measurements. It is not to be expected that more stations 

 will disprove the variability of the sun; they will only establish more 

 accurately its amount. Since all weather phenomena are the result 

 of the sun's radiation, any change in that radiation must produce a 

 corresponding change on the earth. The only question is as to the 

 kind and magnitude of this change. The sun's radiation is partly 

 reflected from the outer atmosphere, and partly absorbed, mainly in 

 the lower levels, while the remainder is absorbed at the earth's surface. 

 If the sun's variability is known, a rough computation can, therefore, 

 be made of the kind of result to be expected. Abbot and Clayton have 

 gone far enough to show that there is considerable value in the effort 

 to correlate the variations in the solar constant and in the weather, 

 and at least six stations should be established to carry forward the 

 study of the solar constant. 



All of Clayton's deductions, however, are not sound. What he calls 

 a "stable system" would not necessarily result if there were no varia- 

 tion in solar radiation. A river with a constant supply of water and 

 undisturbed at its mouth by tides may still be full of turbulent currents. 

 The weather cannot be dependent solely on changes in the sun. 



The location of Buenos Aires is unfortunate for an attempt to cor- 

 relate weather and solar variation. An inland high-level station would 

 be much better. The lower levels of the atmosphere near the sea are 

 usually moist and dusty and do not respond as quickly as the high levels; 

 variations in the wind direction, especially as between on and off shore, 

 are also most disturbing near the coast. 



