Researches on Solar Physics. 327 
Finally, in series Iv, vit, X10, and xrx we have probably a 
minimum near the center accompanied with a somewhat unde- 
cided action. The dates of these series are :— 
LV, August, 1865.2. 4. > ; : i 
VIl, August; 1967...05, Eyl Sik eeinbel ede amet AE Liaw 6: os. months. 
\ hence XII Ii+19 
XIII, March, 1859 ...... { XIX=XIII-+16 « 
RIX, July, 1860 ..nsd< i ica 
Mean, 20. = 
The period of recurrence of the same behavior would thus 
appear to be nineteen or twenty months. 
47. In the third place, in all these recurrences the progress of © 
the maximum is from left to right, not right to left. Thus in 
series III the maximum is near the center, while in series Iv it 
has gone to the right. The same order is observable in series X 
and X1, and in fact, throughout the whole twenty series. 
48. We cannot see that these phenomena can possibly be 
explained, unless it be admitted that the behavior of the sun- 
size. An examination of the table on p. 826 will give us some 
idea of the nature of the influence probably exerted by Venus. 
The average size of a spot would appear to attain its maximum 
On that side of the sun which is turned away from Venus, and 
to have its minimum in the neighborhood of this planet. oo 
_ But, it will be asked, does not Jupiter appear to exert any 
influence? for although its distance is much greater than that of 
enus yet its mass is very great. A reference to the table will, 
