president's address. 37 



varying rates of change have undoubtedly been the rule. At the 

 present time all the indications appear to point to the world's 

 beinof in the waning stage of a glacial period, so that warmer 

 conditions are now steadily invading the circumpolar regions. 



The question naturally arises at this stage, what would be the 

 effect of the escape of internal heat from the earth in aiding the 

 carbon dioxide of the atmosphere to maintain a genial climate. 

 This problem was long ago dealt with by Sir William Thomson 

 (Lord Kelvin), who arrived at the result that, starting with an 

 incandescent globe, •' the general climate cannot be sensibly 

 affected by conducted heat at any time more than 10 000 years 

 after the commencement of superficial solidification."* The 

 same authority elsewhere says : " Ten, twenty, thirty times the 

 present rate of augmentation of temperature downwards could 

 not raise the surface temperature of the earth and air in contact 

 with it more than a small fraction of a degree Fahrenheit. The 

 earth might be a globe of white-hot iron covered with a crust 

 of rock 2,000 feet, or there might be an ice-cold temperature 

 everywhere within 50 feet of the surface, yet the climate could 

 not on that account be sensibly different from what it is, or the 

 soil be sensibly more or less genial than it is for the roots of 

 trees or smaller plants"! 



The view has been held by some observers that the internal 

 heat of the earth was a sufficient source of warmth to maintain 

 a uniform genial climate over the entire surface of the globe 

 during long periods of geological time, and that the sun's heat- 

 ing influence during these periods was effectually neutralized by 

 impenetrable banks of cloud. The ocean was supposed to be kept 

 warm by contact with the heated earth. J Lord Kelvin, as is seen 

 from the above quotations, gives absolutely no support to this 

 theory. Likewise regarding the belief that the rate of cooling of 



* Mathematical and Physical Papers, Vol. iii., 1890, p. 305. 



t Trans. Geol. Soc. Glasgow, Vol. v.. Part ii., 1877, p.250. Kelvin, 

 Popular Lectures and Addresses, Vol. ii., 1894, p.297 



t See, for example, Manson, ' The Evolution of Climates,' The American 

 Geologist, 1898. 



