OF GEOLOGICAL DYNAMICS. 127 



the possible total of plutonic energy at present in 

 the earth, by tracing its history backwards to its 

 probable origin. 



PART III. NOTE ON THE METEORIC THEORY 

 OF THE SUN'S HEAT. 



[Front Report of the Glasgow Philosophical Society's 

 Meeting of March 24, 1869.] 



40. SIR WM. THOMSON, in reply to a question 

 from the President, Dr. Bryce, said that his 

 contribution to the meteoric theory of solar 

 heat had been to point out that the meteoric 

 supply could not be perennial. In his paper 

 " On the Mechanical Energies of the Solar 

 System" (Trans. R.S.E., April, 1854: republished 

 in Math, and Phys. Papers, Vol. II., pp. 1-25), 

 he had shown that meteors falling from extra- 

 planetary space in sufficient abundance to generate 

 the heat emitted from the sun for the last 2000 

 years, must, by the augmentation they must have 

 brought to the central mass, have caused a gradual 

 shortening of the year of which the accumulated 

 effect during that period must have dislocated the 



