690 DIURNAL VARIATION OF THE MAGNETIC DECLINATION, ETC. 



the most brilliant aurorse near the epoch of opposition. These observations and 

 conclusions may give some support to the suggestion I have made as to the action 

 of the moon on the earth's electro-sphere, the tension of which I have supposed 

 to depend upon that of the sun. 



I would draw attention again to Mairan's theory, of a connection betwixt the 

 zodiacal light and the solar light. I asked before, "Is the zodiacal light not the 

 magnetic [or electric] ether in a luminous state?" * I have frequently observed 

 the zodiacal light in 8^ N. latitude, at Trevandrum, when, according to the obser- 

 vations, the summit of the lens of light must have considerably surpassed the 

 zenith at sunset. Whatever this light may be, or whatever its cause, it cannot 

 fail to act upon the earth and its satellite, and to be acted on by them. That it 

 extends far beyond the earth's orbit in a non-luminous state, and that it is acted 

 on by more distant planets than the earth, seems to me probable ; and it may be, 

 that in this action we should seek the connection betwixt the position of the 

 planets and the solar spots ; which spots I have already suggested, are disruptions 

 of the electric atmosphere of the sun,f disruptions passing through the photo- 

 sphere — the photosphere itself being the dense base of the zodiacal light. 



* See Letter, dated Trevandrum, 21st December 1857. Philosophical Magazine, July 1858. 

 | See Letter just cited, where I have also noticed that Cassini and Mairan supposed a con- 

 nection betwixt the intensity and extent of the zodiacal light and the solar spots. 



