SUNSfflNE ON THE FARM. 375 



question and answer were on the way. If the explosion of 

 Gen. Butler's famous powder-ship, which occurred during 

 the war, could have been heard at the sun (I doubt if it was), 

 the sound did not reach there until 1876, twelve years after 

 the close of the war. Light from the sun, moving at the 

 rate of a hundred and eighty-five thousand miles in a second 

 of time, reaches us in about eight minutes. It is across this 

 tremendous chasm the sun exercises his power. Every pul- 

 sation of the solar surface is instantly responded to upon the 

 earth. 



In bulk it is a globe having a diameter of eight hundred 

 and sixty thousand miles, and it would take one million and 

 a quarter earths to make a globe of equal size. The temper- 

 ature of the suu is exceedingly intense. If we heat a cannon- 

 ball to redness, and place it in the focus of a concave mirror, 

 the rays of heat collected and condensed by another mirror 

 ten feet away will be hot enough to ignite phosphorus, a very 

 inflammable body ; but, if a lens only three feet in diameter 

 be used to concentrate the sun's rays into a focus, the heat is so 

 intense, that the most refractory solids are instantly melted, 

 or dissipated in vapor. Platinum, fire-clay, and even the 

 diamond itself, are fused, or changed into gaseous condi- 

 tions, if they are exposed to the sun's heat at a distance from 

 it equal to that of the moon from the earth; and therefore, 

 if our earth should fall towards the sun, it would melt, or 

 pass into the liquid or gaseous condition, when as distant 

 from the solar surface as the moon is from the earth. The 

 intensest artificial heat that can be produced reaches perhaps 

 4000° F. It is difficult to ascertain the exact temperature 

 of the sun by any measurements here ; but it is easy to meas- 

 ure the quantity of heat emitted. 



The sun in the zenith, shining upon the earth, emits 

 sufficient heat every two hours and twelve minutes to melt 

 a layer of ice one inch thick over its whole surface. To pro- 

 duce this effect by the burning of coal would require a layer 

 thirteen feet thick all over the sun to be consumed every 

 hour, or two-thirds of a ton per hour to every square foot of 

 surface. Such a fire as this no earthly furnace can parallel. 

 At this rate, if the sun were made of solid coal, he would 

 burn entirely out in six thousand years. These facts afford 



