10 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. Ill 



1.945 calories were subtracted from the fourth list, giving a fifth list 

 of residuals. 



Though convinced of the validity of the assumption of a 273- 

 month master cycle, I have passed over any discussion of the sun- 

 spot cycle of 1I7 years, approximating one-half of the master period, 

 I now take up its consideration before noting the discovery of sev- 

 eral other periodicities. Figure 2, which displays the variation of the 

 yearly means of Montezuma solar-constant values, does, indeed, show 

 depressions at the years 1925, 1931-32, 1937-38, and 1944. These 

 may indicate a sunspot-cycle influence, but might better be attributed 

 to the 68-month cycle which has already been discussed. Moreover, 

 these depressions appearing in figure 2 are very small, with ampli- 

 tudes only about 1/12 of i percent of the solar constant, yet the 68- 

 month curve, when specifically determined as given above, has an 

 amplitude approaching ^ of i percent. 



]\Ieteorologists recognize that the 11 -year sunspot cycle is reflected 

 in temperature, precipitation, and barometric pressure. Aldrich, also, 

 has shown ^ by the study of individual daily values of the sunspot 

 numbers, and of solar-constant values, that there is a complex cor- 

 relation between these phenomena. But my residual plots of monthly 

 solar-constant values do not show any 136-month periodicity of ap- 

 preciable amplitude. This is not really in contradiction to the find- 

 ings of meteorologists. It is well known that the sunspot areas bom- 

 bard the earth with electric ions. These, by acting as centers of 

 condensation for water vapor and dust in the earth's atmosphere, 

 may very well be competent to produce meteorological changes. Be- 

 sides this, the ozone contents of the atmosphere may be affected by 

 them in a way to influence meteorological phenomena. So we may 

 recognize two kinds of solar influences on meteorology. One de- 

 pends on variations of the solar radiation, the other on variations of 

 ionic bombardment. 



Having discovered and evaluated periodicities of 273, 91, 68, 54^, 

 39^, and 15^ months in the variation of solar radiation, as evidenced 

 by monthly mean solar-constant values of Montezuma, I next used 

 the original lo-day mean values to seek for periodicities of less than 

 12 months. For such short periods the longer ones hitherto discussed 

 produce no sensible interference. It would be tedious to recite all 

 these trials. The method was always the same. By means of a long 

 paper scale divided at regular intervals to represent a suspected 

 period, I tested on the long plot of lo-day means whether such a 



^ Smithsonian Misc. Coll., vol. 104, No. 12, 1945. 



