ANALYSIS OF SOLAR RECORDS 



79 



maxima is correct, the sun shares in causing the 6-months maxima. Until 

 this effect is confirmed our results should be considered provisional 



Similar caution must also be exercised in drawing conclusions from this 

 apparent relation between the sun and the earth's magnetism Its display in 

 1932-33 as analyzed in the cycle contours shown in Plate 19C, suggests that 

 these chief magnetic source centers are on opposite sides of the equator and 

 hence diametrically opposite each other at some latitude less than 10°. 



Fig. 33 — International Magnetic Character Figure C as related to opposite longi- 

 tudes on sun during a 27-day period. Note: Means of approximate first halves of suc- 

 cessive 27-day periods provide ordinates for one line and means of second halves of same 

 provide them for the other line. Ordinates are relative values on a special scale with 

 unity approximating 0.13 unit of character figure C per day above an assumed base of 

 about 0.5 unit. This shows alternate 6-months maxima as occurring at the time that 

 opposite solar longitudes (near the solar equator) are central as seen from the earth. 



Other Periods — In 1931 there was evidence of a 9-day period operating 

 coincidently with those of 13.5 and 27 days. Since 1906 it shows durations of 

 more than four months in the following years: 1910, 1914, 1916, 1924, and 

 1931. Of these, 1914 exhibits the unusual length of 9.9 days, which is one- 

 third of a long cycle showing in that year. Maxima, possibly alternating in 

 longitude, show at previous sunspot minima, for example, in 1922 and 1923 on 

 a period of 27.0 days; in 1912 and 1913 on a period of 27.3 days. The year 

 1914 has a period near 29.4 days; 1916-18 give evidence of a possible period 



