ON SOLAE PHYSICS. 
393 
photoheliograph was in the process of removal from Mr. De La Hue’s observatory at 
Cranford to the Kew Observatory. 
The observations up to the end of 1853 are those of Schwabe, those from the begin- 
ning of 1854 to the end of 1860 are those of Carrington, while the remainder constitute 
the Kew series, with the exception of those bracketed and having an asterisk, which are 
derived from Sci-iwabe. 
In Table VIII. we have for every fortnight (beginning with January 14th of each year) 
the readings of the equalized curve or that exhibited by a dotted line. It is proper to 
remark that, in order to obtain these readings, this curve was first laid down on a very 
much larger scale than that exhibited in the accompanying Plate. 
Results of Reduction. 
28. From Table VIII. we obtain the following epochs for the minima and maxima of 
the longer period of solar disturbances : — 
Minimum Nov. 28, 1833 
Maximum 
Minimum 
Maximum 
Minimum 
Maximum 
Minimum 
Sept. 21, 1843 
April 21, 1856 
Dec. 21, 1836 
Nov. 14, 1847 
Sept. 7, 1859 
Feb. 14, 1867 
We deduce from these numbers, in the first instance, the fact of the variability of the 
length of the whole period 
Thus we have from first to second minimum 9 '81 years. 
from second to third 12*58 years. 
from third to fourth ,, 1081 years. 
Mean of the three periods . . . 11 '07 years. 
Secondly, we see that in all of the three cases the time from a minimum to the next 
maximum is less than that from a maximum to the next minimum, — a fact which has, 
we think, been previously noticed by Sir J. Herschel. Thus the time from the first 
minimum to the next maximum is 3*06 years, and from the first maximum to the second 
minimum 6 75 years. In like manner that from the second minimum to the next maxi- 
mum is 4*14 years, and from the second maximum to the third minimum 8 ’44 years. 
Finally, the time from the third minimum to the third maximum is 3*37 years, and from 
the third maximum to the fourth minimum 7 ‘44 years. We see again that the second 
curve, which was longer in period as a whole than either of the other two, manifests this 
excess in each of its branches, that is to say, its left or ascending branch is larger as a 
whole than the same branch of the other two curves, and the same takes place for the 
second or descending branch. On the other hand, the maximum of this curve is not so 
