﻿Reports and Proceedings — Geological Society. 571 



temperature that could be produced on Mallet's hypothesis. He 

 calculates that a mass 100 square miles in area, sinking 1 metre, on 

 the assumption that half the heat developed was produced by 

 friction, and that its effect extended to a distance of one metre on 

 each side of the surface of rupture, could not produce along this 

 surface a rise in temperature of more than 54-7° Centigrade. 



In Appendix II. (pp. 20-24) he cites many observations vphich 

 show that molten metals contain considerable quantities of different 

 gases, and disengage them in cooling and solidifying. 



In Appendix III. (pp. 24-26) he shows that on the supposition 

 of a large number of assumptions the amount of gas developed from 

 the earth would be more than sufficient to account for the volcanic 

 activity we see. His assumptions are, Poisson's calculation of the 

 heat lost annually by radiation : that the additional amount lost by 

 hot springs, lava vents, etc., is one-tenth more : that the latent heat 

 of consolidation is that of iron (which he estimates ingeniously) : 

 that the molten materials at great depths disengage in solidifying 50 

 times their volume of gas : and that the velocity of eruption of gas 

 from a volcanic vent is fifteen metres per second. His result is that 

 the gas disengaged would be sufficient to keep in vigorous activity 

 20,000 volcanic vents, each one square metre in area. 



Though the author's theory is open to some of the objections 

 which he urges against other hypotheses, and though his calcula- 

 tions, as is apt to be the case with such estimates, are of little im- 

 portance, yet it does seem likely to be a partial cause of terrestrial 

 volcanic activity, perhaps the whole cause of solar eruptions ; and 

 the paper, as a clear statement of the theory, is a valuable one. 



E. H. 



i2,s:poiaTS -A-D^HD :PI^oGE:EX)II^^C3-s. 



I. — Geological Society of London. — November 7th, 1877. — 

 Prof. P. Martin Duncan, M.B., F.R.S., President, in the Chair. 



The President announced that M^^ Frederick L. Woodward had 

 been appointed Junior Assistant in the Library and Museum. 



The following communications were read : — 



1. A letter dated Foreign Office. September 14, 1877. 



" Sir, — I am directed by the Earl of Derby to state to you, for the 

 information of the Geological Society, that his Lordship has received 

 a despatch from Her Majesty's Minister at Teheran, reporting that 

 a mining engineer had arrived there from Berlin, who, at the re- 

 quest of the Persian Government, had been selected by Messrs. 

 Siemens to ascertain what foundation there was for the reported 

 existence of a rich vein of gold in the vicinity of Zengan ; that he 

 had visited the locality, and reported that auriferous quartz does 

 exist, but that he had not yet succeeded in finding any vein or de- 

 posit of the metal. — I am. Sir, your most obedient, humble Servant, 

 " The Secretary, Geological Society, etc. JuLlAN Pauncefote." 



2. " Notes on Fossil Plants discovered in Grinnell Land by Capt. 

 H. W. Feilden, Naturalist to the English North Polar Expedition." 

 By Prof. Oswald Heer, F.M.G.S. 



