ON THE SUN'S HEAT. 411 



and amounting in all to a total mass equal to the 

 sun's, are scattered as uniformly as possible on a 

 spherical surface of radius equal to one hundred 

 times the radius of the earth's orbit, and that 

 they are left absolutely at rest in that position. 

 They will all commence falling towards the centre 

 of the sphere, and will meet there in two hundred 

 and fifty years, and every one of the twenty-nine 

 million globes will then, in the course of half an 

 hour, be melted, and raised to a temperature of 

 a few hundred thousand or a million degrees 

 centigrade. The fluid mass thus formed will, by 

 this prodigious heat, be exploded outwards in 

 vapour or gas all round. Its boundary will reach 

 to a distance considerably less than one hundred 

 times the radius of the earth's orbit on first flying out 

 to its extreme limit. A diminishing series of out- 

 and-in oscillations will follow, and the incandescent 

 globe thus contracting and expanding alternately, 

 in the course it may be of three or four hundred 

 years, will settle to a radius of forty l times the 



1 The radius of a steady globular gaseous nebula of any homo- 

 geneous gas is 40 per cent, of the radius of the spheric surface 



