ORIGIN AND AGE OF THE SUNS HEAT. 291 



Prof. Haeckel may make any assumption he chooses 

 about the age of the sun, but he must not do so in 

 regard to the age of the sun's heat. One who believes 

 it inconceivable ih&t matter can either be created or 

 annihilated may be allowed to maintain that the sun 

 existed from all eternity, but few will admit the 

 assumption that our luminary has been losing heat 

 from all eternity. 



If 20,000,000" or 30,000,000 years do not suffice for 

 the evolution theory, then either that or the gravitation 

 theory of the origin of the sun's heat will have to be 

 abandoned. 



It was proved in the last chapter from geological 

 evidence that the antiquity of our habitable globe 

 must be at least three times greater than it could 

 possibly be had the sun derived its heat simply from 

 the condensation of its mass. This proves that the 

 gravitation theory of the origin of the sun's heat is as 

 irreconcilable with geological facts as it is, according 

 to Haeckel, with those of evolution, and that there 

 must have been some other source, in addition, at least, 

 to gravity, from which the sun derived his store of 

 energy. That other source we have just considered 

 at some length, and found it perfectly adequate. 



The theory that the sun's heat was originally derived 

 from motion in space is, therefore, more in harmony 

 with the principles of evolution than the gravitation 

 theory, because it explains how the enormous amount 

 of energy which is being dissipated into stellar space 

 may have existed in the matter composing the sun 

 untransformed during bygone ages, or, in fact, for as 

 far back as the matter itself existed. 



Note on Arguments for the Age of the Earth. — Sir 

 William Thomson has endeavoured to prove the recent 

 age of the earth by three well-known arguments of a 



