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The Heat of the Sun. 
[March, 
which falls upon an area of 50,000,000 square mj le s; multi- 
plying this by 2,300,000,000 we obtain the total amou 
heat emitted by the sun. In speaking of the distance of ^the 
Sun it was stated that we could form no idea of the vastness 
of the distance which separated us from him. _ And, n 
impossible to form an idea of the distance, it is als ° equ a y 
impossible to form an idea of the immense heat which he 
possesses. The highest temperatures which we ^ obtain 
are so cold compared to his temperature that the comparis 
between an Ardtic winter and an Equatorial su ™ m ^ r * s V,, 
inadequate to represent the difference. Thus Prof . ^ 
says— “ The heat emitted by the Sun, if used to melt a 
stratum of ice applied to the Sun’s surface, would liquefy it 
at the rate of 2400 feet an hour. It would bod pei hour 
700,000 millions of cubic miles of ice-cold water. 
Another eminent writer upon this subjedt, S11 John 
Herschell, says “ that the heat thrown out from every square 
yard of the Suns surface is equal to that which would be 
produced by burning on that square yard 6 tons of coa pei 
hour, and keeping up constantly to that rate of consumption. 
And this, mind, on each individual square yard of that 
enormous surface which is 12,000 times that of the whole 
surface of the Earth. . . ^ 
In attempting to bring the imagination to grasp .such 
enormous numbers and statements we are attempting a 
hopeless task ; it recoils from such immensity much as a 
billiard ball recoils from the cushion upon which d jtnkes 
But although thus unable to appreciate such fadts the 
reasoning powers of many (I may perhaps say most) scien- 
tific men have been employed from time to time foi the 
purpose of seeking a cause which shall be a sufficient and a 
possible one to account for this enormous expendituie of 
power,— an expenditure, be it remembered, which has been 
going on, at least during historic times, without the slightest 
^ The theories which have been proposed from time to time 
we will now examine, taking them in the order of their age, 
and impartially examining each. 
The Combustion Theory. 
This is the oldest, simplest, and most unscientific of the 
whole. It cannot be ascribed to any author, and in fadt it 
is probable that most thinkers upon the subjedt, upon a first 
and superficial examination, would propound such an ex- 
planation. Shortly expressed it says that the Sun is a fire, 
