PROFESSOR A. SCHUSTER ON THE PERIODICITIES OF SUNSPOTS. 
93 
explained in § 4, which leads to the results given in Table XV. For each period we 
obtain three numbers according as we use the whole interval or the two separate 
halves. 
Table XY. 
1 
Period. 
Calculated phases of 8'36-year period. 
1749-1900. 
1749-1826. 
1826-1900. 
7-5 
353“ 
210° 
340“ 
7-75 
— 
215 
199 
8 
191 
196 
173 
8-25 
198 
207 
190 
8-5 
217 
201 
221 
8-75 
278 
229 
140 
It will be noticed that, except as regards the values derived from the shortest and 
longest periods included in the table, the phases are concordant. The amplitude 
of this period being only about one-third of that of the 11 years’ period, it is more 
likely to be interfered with by accidental variations, and therefore a closer agreement 
800 
cannot be expected. We may take 206° as the most probable phase, which, converted 
into years, gives 1904‘51 + 8 - 36n as the dates of the maxima of this period. It is 
significant that there are maxima with identical phases for the semi-period of 4T25 
