94 HUXLEY 



Lord Salisbury unwittingly helped the cause which 

 his instincts prompted him to hinder. With that pre- 

 vision of the seer in combination with the skill of the 

 discoverer, which is the possession only of the rarer 

 spirits of our kind, Huxley had pierced the core of 

 the matter when he asked, " Is the earth nothing but 

 a cooling mass, c like a hot-water jar, such as is used 

 in carriages,' or c a globe of sandstone,' and has its 

 cooling been uniform ? " And incited thereto by 

 Lord Salisbury's Address, provocative as it was of 

 discussion on so many sides, Professor Perry, who 

 held the common opinion that it was "hopeless to 

 expect that Lord Kelvin should have made an error 

 in calculation," examined the subject, not " to substi- 

 tute a more correct age for that obtained by Lord 

 Kelvin, but rather to show that the data from which 

 the true age could be calculated are not really 

 available." The result of that examination was to 

 challenge Lord Kelvin's assumption of a uniform 

 state of the materials of the globe, and to show that 

 " its interior may be of better conducting material 

 than the surface rock," whereby the cooling of that 

 surface to a habitable condition would be enormously 

 quickened, and the life-period pushed back to the four 

 hundred million years required by the geologists and 

 biologists. The details of the process by which 

 Professor Perry arrived at his conclusions are too 



