410 
would also cause such daily and annual fluctuations as those of the 
magnetic needle. Professor Norton says* that ‘‘no conception has 
hitherto been formed of possible atomic movements capable of originating 
the electric forces, and producing even the simplest of the electrical 
phenomena.”? The dependence of the polarity of the compass upon 
electrical currents encourages the belief that all the ‘possible atomic 
movements capable of originating the electrie forces,’’ may be traceable 
to some arrangement of elastic ethereal particles like the one I have 
above suggested. The mutual attraction of the atoms A and E is only 
one-third as great as that of the atoms F and G, and under the influence 
of centrifugal force, the several lozenges AFEG would yield most readily 
in the direction EG. 
THE SUN-SPOT CYCLE OF 11.07 YEARS. 
By Puiny EARLE CHASE. 
(Read before the American Philosophical Society, May 16th, 1872.) 
The most recent and careful discussion of the observations upon the 
amount and frequency of Sun-spots, by De La Rue, Stewart and Loewy, | 
assigns to the principal cycle a duration of 11.07 years. Kirkwood 
(ante, vol. xi., p. 100) had previously given nearly the same esti- 
mate (11.072 years). If the spots are attributable to disturbances 
produced by gravitating action, the maj O8 axis of the revolving dis- 
cobs 
turbing force should be [(11.07+11. 862) ]j=.955x<Jupiter’s, or 4.969 
<the Earth’s major ax 
The mean radius vase of perturbation is, 
therefore, n yin equivalent to Jupiter’s mean perihelion distance 
(.951843/, or 4.952) as well as to the mean distance of the centre 
of gyration of the planetary sytem. 
2 sng <.3871 +25. 7233 +31.85 1+ 3: 37-+-9807 5, 2028 + 2847.4 
uA 7 X<19.1826-+532.5 >< 80. oo + (B4+-254-31.85-4 oT |-9307-- 2847.4 
5.101 3 5.101-+4.969—1.0265 ; 4.969--4.952—=1.00385. 
The theoretical mean excursion between ie s perihelion and his 
mean distance, corresponds very nearly with the above value of the 
planetary centre of gyration. 
4,952 4-2 (5.2028 —4.952)==5.091 ; 5.101--5.091—1.002. 
If Jupiter’s aphelion distance yepredentl the aphelion distance of the 
ak care, or forces which produce the Sun-spots, the disturbance-peri- 
helion is (2.955 —1.048)—=.862 2/’s, or 4.485 @’s radius vector. This 
corresponds very nearly with the linear centre of oscillation, of the mean 
* OG, Cite D. an0s 
t Proc. Roy. Soc., Dee. 21, 1871; Phil. Mag., May, 1872. 
se.] {May 16, 
ac cialseiacaeia 
