NO. 13 SHORT PERIODIC SOLAR VARIATIONS ABBOT 5 



and 1946-48 were kept separate from the years 1931-35 and 1942-45. 

 In anticipation, it may be remarked that slight displacements of 

 maxima and minima seem to attend both the time of the year and 

 the epoch of the sunspot cycle. But these displacements are so small, 

 and the effect of the 6.6485-day period is so pronounced, that a direct 

 mean of all the evidence, for all months and all years, shows dis- 

 tinctly the main features of the frequency of distribution of the 

 temperature departure features. 



Table 2. — Frequency of temperature minima in the seven columns 



No. of 

 Lines Station 1234567 years 



I New York 52 30 30 42 25 26 47 21 



2 Washington 44 35 23 46 26 23 55 21 



3 New York 28 15 20 25 17 13 26 12 



4 Washington 23 18 15 31 12 18 27 12 



S New York 26 15 10 17 8 13 21 9 



6 Washington 21 17 8 15 14 5 28 9 



7 New York 2.33 1.25 1.67 2.08 1.42 1.08 2.17 i 



8 Washington 1.92 1.50 1.25 2.58 i.oo 1.50 2.25 i 



9 New York 2.67 1.67 i.ii 1.89 0.89 1.44 2.33 i 



ID Washington 2.33 1.89 0.89 1.67 1.56 0.56 3.10 i 



II + + - - ■ T ± + 



Explanation. — Lines i, 2 cover monthly means for all years, 1928-1948. 



Lines 3, 4 cover monthly means for years of sunspot maximum. 



Lines 5, 6 cover monthly means for years of sunspot minimum. 



Lines 7-10 cover as lines 3-6, but are general averages for i year 

 only. 



Line 11 shows when years of sunspot minimum have higher fre- 

 quencies. 



In table 2 and figure i are given the frequencies with which 

 minima in all the monthly mean tables combined (similar to table i ) 

 fall in the seven different columns of the tabulations. For curiosity's 

 sake the table also gives the average numbers per month of occur- 

 rences of mean minima for sunspot maximum and sunspot minimum 

 years separately. Reducing the values to equal numbers of years, it 

 will be seen from these latter tabulations that for both Washington 

 and New York there is a tendency in sunspot mininuim years for 

 minima to occur with greater frequency in columns i, 2, and 7, and 

 lesser frequency in columns 3, 4, 5 and 6. This shows that the prin- 

 cipal solar period has better control over terrestrial disturbances when 

 sunspots are at minimum. But ignoring this subordinate result, the 

 main results of the tabulation show that : 



I. There is a great and nearly equal preponderance of frequency 

 for both stations in columns i and 7, so that the minimum falls at 

 about half a day after 7 in both cities. 



