124 
No. 
Date. 
Mag. 
Days 
in 
Interval. 
Number 
of 
Periods. 
9. 
1863, May 30... 
... 9*2 
214 
3 
10. 
„ July 29.. 
... 9-1 
60 
1 
11. 
,5 Oct. 15... 
... 9*3 
78 
1 
12. 
„ Dec. 22... 
... 9'2 
67 
1 
13. 
1864, May 25... 
... 8-9 
155 
2 
14. 
„ Sep. 28... 
... 8*8 
126 
2 
15. 
1865, July 9... 
... 8'8 
284 
4 
16. 
„ Sep. 20... 
... 8-9 
73 
1 
17. 
1866, July 5... 
... 9-0 
288 
4 
18. 
„ Sep. 3 . . . 
... 8'9 
60 
1 
19. 
„ Nov. 15... 
... 9-2 
73 
1 
20. 
1867, Aug. 28... 
... 9-1 
286 
4 
21. 
„ Nov. 6... 
... 8'9 
70 
1 
22. 
1868, Oct. 17... 
... 9'4 
345 
5 
23. 
1878, July 16... 
... 9'4 
3559 
51 
24. 
„ Dec. 5... 
... 9-4 
142 
2 
25. 
1879, Sep. 3... 
... 9*4 
272 
4 
26. 
„ Nov. 14... 
... 9-3 
72 
1 
Treating 
these data by 
the method adopted with 
principal minima the resulting mean period = 70 '173 days; 
and the epoch 1866, June 20*929. 
Comparing these elements with those derived from the 
principal minima, it will be seen that the mean interval 
between a principal minimum and the following secondary 
minimum is 34'886 days, or almost exactly half the whole 
period. 
My observations have enabled me to determine the times 
of 24 principal, and 19 secondary maxima, and comparing 
them with the times of the preceding principal minima I 
find that the mean intervals are respectively 14'8 and 45 '6 
days. Dr. Schonfeld in his Zweiter Catalog von verander- 
lichen Sternen, gives the mean intervals derived from his 
own observations in 1865-70 as follows : — 
