NOTE V 



Not only this, but that similar correlations are found also in Mr. Clay- 

 ton's former paper as between the weather of nearly 50 stations in 

 remote parts of the world and the observations made at Mt. Wilson, 

 California. In an unpublished communication by Dr. Nansen he 

 informs me that similar correlations are found between the tem- 

 ])eratures of Norway and Sweden and the solar results in California. 

 Furthermore, my own studies and those of Mr. Clayton show, for 

 example, that in the year of 191 5 the solar observations indicated the 

 existence of a warm and a cold hemisphere of the sun, so that high 

 values of the solar radiation were repeated after intervals of about 

 2"] or 28 days, corresponding to the well-known rotation period of 

 the sun. The same effect is found by Mr. Clayton in the study of the 

 temperature of Buenos Aires, and the reader's attention is particu- 

 larly drawn to the curves a, b, a', and &' of figure 4 of the accompany- 

 ing" paper. But it is not alone with respect to temperatures and rain 

 fall that the correlations as found by Mr. Clayton exist. As shown 

 in a paper, " On the Distribution of Radiation over the Sun's Disk 

 and New Evidences of the Solar Variability," ^ there is also a correla- 

 tion between variations of the distribution of radiation along the 

 diameter of the sun's disk and variations of the solar constant of 

 radiation. Other investigations by different authors have also 

 pointed out dependencies of various quantities on the supposed varia- 

 tions of solar radiation. It seems to me that in view of the wide- 

 reaching and variegated character of the dependencies which have 

 been found, it must be admitted that the variation of the sun is a real 

 phenomenon and not an apparent result derived from the effects of 

 terrestrial causes on the solar observations. 



I would like to draw the reader's attention in particular to num- 

 ber 7 of the conclusions which Mr. Clayton states in the summary of 

 his research. In this he points out that variations of temperature in 

 Argentina agree well in number and in magnitude to the variations 

 which would be expected in view of the supposed changes in the solar 

 radiation. It is this and many other features of his research which 

 have led him to the conclusion that the weather as distinguished from 

 the climate is governed by variations of the sun and would be predict- 

 able both qualitatively and quantitatively if we had daily accurate 

 determinations of the solar variation. If this be true, we stand, it 

 seems to me, on the threshold of a very important research in meteor- 

 ology. What is needed is the establishment of sufficient stations for 



^ Smithsonian Misc. Coll., Vol. 66, No. 5, 1916. 



