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the sun than question why he shines.” Notwithstanding this, 
how many conjectures have been formed on this subject ! Our 
forefathers, who were ignorant of the voltaic pile and electricity, 
attributed the light and heat of the sun to material fire. May 
there not be other agencies unknown to us which would explain 
the incandescence of the sun? An eminent authority, whilst 
favouring the idea of a perpetual electric discharge, frankly 
confesses that every discovery of this kind seems “ to remove 
further the prospect of probable explanation.” In addition to 
the energetic action of the currents of the galvanic pile, other 
remarkable ideas have been started. It has been demonstrated 
by Thompson and Watherston that if five pounds of cosmical 
matter were to fall on each square foot of the solar surface, and 
the body was going at the rate of 390 miles per second, that 
the heat and light resulting from the shock would be sufficient 
to account for that actually existing on the sun. Those falling 
bodies must be searched for in the shooting stars, and probably 
in the zodiacal light. Messrs. Carrington and Hodgson have 
witnessed a phenomenon which favours this conjecture (a por- 
tion of the solar surface blazing suddenly for an interval of 
about ten minutes), yet the theory which attributes the lustre 
of the sun to the continual formation of torrents of electricity 
engendered by the clouds of the various envelopes, would seem 
to obtain the greater number of suffrages among astronomers.* 
It might be added that, as the northern lights sensibly affect 
the magnets, it has been noticed that the phenomena connected 
with the sun also appear to exert a certain influence on them. 
General Sabine has shown that the maximum variation of the 
needle corresponds with the greatest abundance of the solar 
spots. The dependence of the magnetic intensity on the solar 
altitude is well known; and it has also been found that the 
earth’s magnetic force is greatest at those seasons when our 
globe is nearest the sun. Admiral Smyth may well say, on 
this subject, that a “ wonderful coincidence seems to be satis- 
factorily established therein, a mine is sprung, the extent of 
which lie is a bold man who will venture to predict, although 
inductive experience is allowed to adopt the tone of prophecy.” 
* Professor Thomson considers that meteoric action is the only explana- 
tion which can he given in respect to the heat and light radiated by the sun. 
Chemical action is insufficient to account for it, whilst meteoric action depends 
on independent evidence. The former could generate only about 3000 years’ 
heat, the latter would account for twenty million years of solar heat. And 
what a degree of heat too — sufficient to keep up a 63,000 horse power. 
Each square yard of the solar surface representing the consumption of 13,500 
pounds of coal per hour, and where forty feet thickness of ice would thaw per 
