Chase. 1 



438 



[October. 



It seems not improbable that the mutual planetary perturbations 

 which are sufficiently powerful to affect their orbital revolution, may 

 also exert an appreciable influence on their asthereal spheroids, and 

 that numerous cyclical magnetic variations may be thus produced. 

 The disturbance of Jupiter is by far more important than that of any 

 other planet, its mean attractive energy being nearly a third propor- 

 tional to those of the sun and moon.* The annual fluctuations are 

 very great, the intensity being about ji^ when Jupiter is nearest 

 the earth, and less than half as great, or only about ^l^, when most 

 remote. The combined operation of the tropical revolutions of 

 Jupiter, the moon's apsides, and the moon's nodes, should produce 

 a series of disturbances corresponding very nearly in duration with 



TABLE VI. 



Solar and Lunar-Daily Tales of Total Force. 



* If we take as our unit the moon's attraction for the earth f-r-, he sun's will 



be about 177, and Jupiter's y^:j. 



