280 Correspondence — Dr. Irving — Dr. H. J. Johndon-Lavis. 



the earth can go on for ever as it is. illuminated by the sun from 

 infinity of time past to infinity of time future, always a habitation 

 for race after race of plants and animals, built on the ruins of the 

 habitations of preceding races of plants and animals. The doctrine 

 of the 'Dissipation of Energy' forces upon us the conclusion that 

 within a finite period of time past the earth must have been, and 

 within a finite period of time to come must again be, unfit for the 

 habitation of man as at present constituted, unless operations have 

 been, and are to be, performed, which are impossible under the laws 

 governing the known operations going on at present in the material 

 world." 



There can be no necessity for pointing out the importance of this 

 dictum from the pen of Lord Kelvin ; it supports my own contention 

 in the Geological Magazine of July and October, 1891 (pp. 300 and 

 479-80). I will not intrude upon your space by reiterating what 

 I have already put into print, but I trust you will, with your usual 

 courtesy, allow me to refer the reader to such passages as are to be 

 found in my little work.' In the light of what I have quoted above 

 from Lord Kelvin it can scarcely be said that I spoke too strongly 

 in animadversion on the Huttonian School, in the concluding 

 paragraph of my "Note on the Airolo Schists Controversy" in 1890 

 (See Geol. Mag. Dec. III. Vol. VIL p. 259). 



The concluding paragraph of Sir A. Geikie's Presidential Addi-ess 

 to the Geological Society for 1892 shows how opinion is veering at 

 the present moment ; and during the present session two papers 

 of importance have appeared, one by Professor Bonney and Gen. 

 MacMahon, another by Messrs. Dakins and Teall, in which attempts 

 have been made to work out the history of the structural phenomena 

 observable in igneous masses of particular areas on principles 

 applicable to an universal magma, at a period of the Earth's history 

 when the energy since dissipated by radiation into space was con- 

 centrated in the lithosphere. A great deal of what the writers 

 referred to have now put forward was seen more than forty years 

 ago by that sagacious geologist, the late Prof. John Phillips, F.K.S., 

 as applicable to the crystalline rocks of the Malvern range (see 

 Mem. Geol. Survey, vol. ii. part 1), which he saw, with an insight 

 not befogged by the later mists of "regional metamorphism," to be 

 in the main a truly igneous series. On the Malvern Crystallines 

 I hope, after ten weeks' hammering at them, to have more to say 

 anon. A. Irving. 



Wellington College, Berks, 

 nth May, 1892. 



EARTHQUAKE SOUNDS. 



Sir, — There are one or two points in Mr. C. Davison's paper on 

 earth-quake-sounds I should like to draw attention to. 



In most Italian tectonic earthquakes, the sound phenomena pre- 

 cede the mechanical disturbances, though the former overlap the 

 latter the nearer the epicentrum is approached. This means that 



» " Metamorphism of Eocks" (London, 1889), see pp. 18, 19, 22, 23, 70, 71, 94, 

 95, and 96. 



