RANGE AND THE PERIOD OF SOLAR SPOT FREQUENCY. 549 
From the sun-spot epochs the intervals are 
y y y y y 
4-60 7-90 4 ; 10 7-10 3'40 
(1) <2) (3) (4) (5) 
The order of magnitude of the shorter intervals (minimum to maximum) is 5, 3, 1, 
for both sets of numbers; the order for the longer intervals (maximum to minimum) 
is 4, 2, also for both sets of numbers. This shows how complete is the relation 
between the two phenomena. 
The mean of the three intervals from minimum to maximum of magnetic effect is 
v y 
417, and of sun-spot frequency is 4'03 ; the mean of the two intervals from maximum 
v y 
to minimum of magnetic effect is 7'38, and of sun-spot frequency is 7'50. Whole 
y y 
period of magnetic effect 11'55, of sun-spot frequency 11'53. 
It is to be remarked that the extreme points of curves having small irregularities, 
such as are seen on the diagram, do not quite fairly represent the actual epochs of 
minimum and maximum. The numbers contained in Table II. (and also Wolf’s 
corresponding numbers) were therefore smoothed, by numerical process, as seemed 
necessary, and epochs of minima and maxima again selected, with the following result. 
Table IV.—Epochs of minima and maxima of extreme points of the curve numbers 
after being smoothed. 
Epoch, 
Sun-Spot 
Epoch. 
Excess above Sun-Spot Epoch. 
Phase. 
Declination. 
Horizontal 
Force. 
Mean 
Magnetic 
Effect. 
Declination. 
Horizontal 
Force. 
Mean 
Magnetic 
Effect. 
Minimum 
18441 
1842-9 
1843-65 
1843-7 
y 
+ 0-7 
V 
-0-8 
-0-05 
Maximum . 
1848-2 
1848-7 
1848-45 
1848-2 
o-o 
+ 0-5 
+ 0-25 
Minimum 
1857-0 
1855-3 
1856-15 
1856-0 
+ 1-0 
-0-7 
+ 0T5 
Maximum . 
1860-4 
1860-3 
1860-35 
1860-2 
+ 0-2 
+ 0-1 
+ 0-15 
Minimum 
1867-2 
1867-0 
1867-10 
1867-2 
o-o 
-0-2 
-o-io 
Maximum . 
1871-0 
1870-8 
1870-90 
1870-7 
+ 0-3 
+ 0-1 
+ 0-20 
Mean Excess at Epoch of Minimum 
+ 0-57 
-0-57 
o-oo 
Mean Excess at Epoch of Maximum 
+ 0T7 
+ 0-23 
+ 0-20 
General Mean Excess 
+ 0-37 
-0-17 
-h0-10 
Taking differences between the magnetic epochs of minimum and maximum, as 
before, we obtain the intervals 
4'80 7'70 
the sun-spot epoch intervals being 
4'50 7'80 
(1) (2) 
4'20 6'75 3'80 
4'20 7'00 3'50 
(3) (4) (5) 
4 B 
MDCCCLXXX. 
