ii PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [vol. lxxix, 



Street, Elsternwick, Victoria (Australia) ; Evan Llewelyn Da vies, 

 B.Sc., Tregenna, Clvclach (Glamorgan) ; James Johnstone, B.A., 

 M.B., F.R.C.S., 90 King's Road, Richmond (Surrey) ; George 

 Mitchell, M.Inst.C.E., 41| Union Street, Aberdeen; the Rev. 

 Charles Overy, St. Frideswide's Vicarage, Oxford ; William Poxon, 

 Southgate View, Clowne, near Chesterfield ; George Norman Scott, 

 M.Sc, H.M. Inspector of Mines, 22 Richmond Road, Handsworth, 

 Birmingham ; James Clark Templeton, B.Sc, c/o the Bitumen 

 Company, Gjorgiceva Ul. 2/II, Zagreb (Yugoslavia) ; and Wilfrid 

 Seymour Walker, c/o Strick, Scott Ltd., Mohammerah (Persia), 

 were elected Fellows of the Society. 



The List of Donations to the Library was read. 



Prof. Arthur Stanley Eddington, M.A., F.R.S., Pres.R.A.S., 

 then proceeded to deliver a lecture on The Borderland of 

 Astronomy and Geology. He considered first, in reference to 

 rival hypotheses as to the origin of the Earth and the solar system, 

 the general evolution of the stellar universe. The trend of modern 

 astronomy is against the view that luminous stars are being formed 

 b3 r collisions of extinct stars (unless very exceptionally) ; the stars 

 now observed have systematic relations one to the other, apparently 

 indicating that they have been formed as the result of a single 

 evolutionary process sweeping across the primordial matter. 

 Collisions, in any case, would be extremely rare, since dynamical 

 arguments indicate that extinct stars cannot greatly outnumber 

 the observed luminous stars. Whether the original matter was 

 gaseous or meteoric, it must have become entirely gaseous at a 

 very early stage in the formation of a star : this is inferred from 

 the fact that the masses of stars differ very little one from the 

 other, and agree numerically with a certain critical mass, predicted 

 theoretically for a sphere of gas, but unexplained if the star 

 consisted of a swarm of meteorites. It is supposed that radiation- 

 pressure was instrumental in breaking up the original matter 

 into separate stars. These considerations favour the nebular 

 hypothesis ; but, if we accept Jeans's suggestion that the solar 

 system is an exceptional formation, and that undisturbed stars 

 cannot give birth to a planetary system, the argument is less 

 cogent, since it refers only to stars developing normally. .Astronomy 

 now demands a great enlargement of Lord Kelvin's time-scale for 

 the age of the sun ; the most direct evidence is obtained from 

 Cepheid variables, which are found to be developing at only 1/500 

 of the rate which Kelvin's hypothesis assumed. The sun must at 

 one time have given out from 20 to 50 times as much heat 

 as it emits now; but it is uncertain whether any geological 

 strata go back to an epoch when the sun was sensibly hotter 

 than now. Darwin's views on tidal evolution and the origin of 

 the earth-moon system seem to have held their own against 

 all criticism. The present rate of lengthening of the day (deduced 

 frorn ancient eclipses) is about 1 minute in 6 million years ; it 



