CA USE OF SOLAR HEA T. 58^ 



of Alpha a Sun more massive than our own. If there is, then Alpha of the Cen- 

 taur does not traverse a path oi regular c\xxva.tVirQ. , Neither does any other Sun 

 owing to mutual attraction. Assigning to the nearest sun to ours a mass equal to 

 the solar, assume our Sun to dwindle to a point, then its minimum velocity is 14a 

 miles per hour. 



Continuing research, let us recede to forty trillion miles, when we find that 

 a mass there must move on an orbit ninety-nine miles per hour or fall toward the 

 Sun. Seeking to escape solar gravity we sink in space to the appalling depth of 

 13,384 trillion miles, when behold ! we still are dominated by his colossal power. 

 Indeed ! a sun at that distance of must fly on a gigantic curve five miles per hour or 

 yield to solar force and fall. Or, having reached that point from infinite distance 

 its falling velocity would be seven miles per hour. Light requires 2,880 years to 

 traverse 16,384 trillion miles. But, a sun at that distance may not obey ours, its 

 varying path may be determined by others nearer or more massive, and by none 

 of these long at a time, since all suns shift position. Some suns are seen to 

 move with greater velocity than theory demands, hence let us make further re- 

 search in this exciting field. 



New Windsor, III., January, 1885. 



CAUSE OF SOLAR HEAT. 



PROF. RICHARD A. PROCTOR. 



Professor Young, of Princeton, in a recent address at Philadelphia, expressed 

 his belief that the contraction theory of the sun's heat is the true and only avail- 

 able theory. I believe so, too, and my object in the present paper is to dwell 

 upon the significance and interest of this remarkable interpretation of the solar 

 mechanism. 



Of course it is known to all that the old theory according to which the sun's 

 heat is due to combustion ("doubt that the sun is fire," said Shakespeare, as if 

 the doubt was the quintessence of absurdity) has long since been rejected as futile. 

 A mass of the best combustible material, equal to the sun in quantity, would be 

 burned out at his actual rate of emission — if it could burn right out — in about 

 five thousand years. In like manner the idea of the sun as an intensely hot body 

 simply radiating its heat into space, as a piece of white-hot iron does, without any 

 process of combustion, has had to be rejected. Even if the sun were formed of 

 matter possessing the high specific heat of water which has the remarkable prop- 

 erty of giving out more heat in cooling than any other natural substance known: 

 (and only one or two artificial substances surpass it in this respect), even then 

 the sun's emission of heat at his present rate would not cover more than about 

 5,500 years. Processes of chemical change have been suggested as aff'ording the 

 true source of solar heat ; but they in turn have had to be rejected as altogether 

 insufficient. It is unnecessary to touch on the supposed origin of solar heat ia the 



