PROFESSOR A. SCHUSTER ON THE PERIODICITIES OF SUNSPOTS. 
85 
Table X. 
1 . 
2. 
3. 
4. 
5. 
6. 
7. 
8. 
44,423 
41,514 
36,480 
37,004 
33,806 
32,660 
30,671 
32,407 
662 
598 
128 
276 
445 
209 
171 
23 
3,211 
2,117 
— 
— 
— 
— 
9. 
10. 
11. 
12. 
13. 
14. 
15. 
16. 
32,476 
38,929 
30,881 
32,326 
43,254 
36,576 
38,499 
47,869 
278 
7. 
313 
50 
273 
298 
742 
639 
The rows to be added in future should be formed as follows : to the first number 
(44,423) add the sum of the mean daily areas of those four successive rotations, 
the first of which carries the number 605 in Carrington’s series and begins on 
December 18, 1898. This number (662) and the following ones completing the first 
new low ha's e been entered in the table, as well as the two first numbers belonging 
to the second row. In each new row the number of the first rotation which is taken 
into account is that included in the expression 605 + 64 n. If the new set of numbers 
is treated separately and a change of phase is found to occur, this would indicate 
a change in the periodic time. For the purpose of estimating the change, the above 
phase should be considered to belong to the mean point of the interval hitherto 
treated, i.e., to June, 1865. 
lw. Although the period ol 4‘38 does not rest on so secure a basis as the one 
ve ha\e just discussed, it has been very regular in its action during the last five 
cycles. There have been notable outbreaks of sunspot activity during the rotations 
398 (July 4, 1883), 463 (May 11, 1888), 518 (June 19, 1892), 579 (January 8, 1897), 
and 637 (May 10, 1901), which seem to belong to this period. The maxima take 
place at dates which may be calculated from the expression 1897‘00±4-38 x n, 
where n is an integer. Table XI. is constructed similarly to Table X., but as the 
peiiod floes not contain an integer number of four rotations, a certain adjustment 
in the succession of rows, to prevent a systematic shift of phase, had to be introduced. 
The row of numbers may, however, now be used to represent the periodicity of the 
indicated duration, and further rows should be added by beginning each of them 
