442 Chronicles of Science. [July, 



of Mr. Archibald Geikie (Director of the Geological Survey of 

 Scotland), continuing to do good work. 



' The Transactions of the Geological Society of Glasgow '* is 

 marked by Sir William Thomson's celebrated paper " On Geological 

 Time." Considering the motions of the earth, with a careful 

 regard to the effect of resistance and retardation by tidal influence, 

 &c., and viewing the sun as we should any large mass of molten 

 iron, or siHcon, or sodiiun, he comes to the conclusion that : (1) The 

 earth formerly rotated more rapidly than at present, and that its 

 speed is slowly, but cei-tainly diminishing by resistance. (2) That 

 the sun's energies in giving hght and heat are being dissipated 

 year by year, and that there is no sufficient supply of new matter 

 falling into the sun's orbit to replenish that energy. (3) That 

 the sun may have illuminated the earth for 100 millions of years, 

 but that it is almost certain that he has not illuminated it for 

 five times that period. (4) From the author's investigation's 

 of underground temperatures and the secular cooling of the earth, 

 he infers that the present condition implies either a heating of the 

 surface within the last 20,000 years of as much as 100^ Fahr, or 

 a greater heating all over the surface at a more remote period. 



(5) Sir William Thomson shows, in conclusion, that taking the 

 largest grant of time, and commencing with the earth at a tempe- 

 rature sufficiently high to melt its entire mass, we must admit a 

 limit of between 50 millions and 300 milhons of years, beyond 

 which our drafts on the bank of Time cannot be honoured. 



(6) The Dynamical theory of the sun's heat renders it impossible 

 that the earth's surface has been illuminated by the sun many 

 times 10 million years. (7) Finally, he concludes that the existing 

 state of things — including life on the earth — must be limited within 

 some such period of past time as 100 million years. We should 

 like to notice Messrs. James Geikie, " On Denudation in Scotland 

 since Glacial Times ;" Archibald Geikie, " On Modern Denudation," 

 and " On the Silurian Eocks of Scotland ;" Mr. Edward Hull, " On 

 the Causes which seem to have regulated the relative Distribution 

 of the Calcareous and Strata of Great Britain, with special refer- 

 ence to the Carboniferous Formation ;" besides many other excellent 

 papers, but our space does not permit. 



Ppoceedings of the Geological Society of London. 



The May number of the 'Quarterly Journal' t furnishes ua 

 with the Annual Ecport, the Anniversary Address by the President, 

 and the papers read before the Society from December 23, 1868, 



• 1868. Vol. TIL, part i. 



t Edited by Mr. W. S. L)all;i.><, tlio now assistniit-socretary. 



