Proceedings of Learned Societies. 219 



PROCEEDINGS OE LEARNED SOCIETIES. 



BY W. B. TEGETMBIER. 



MEETING OP THE BRITISH ASSOCIATION AT BATH. 



On the evening of Wednesday, September 14, Sir Charles Lyell, 

 the President of the Association, delivered his inangural address, 

 He began by reference to those thermal springs, which, from the 

 time of the Romans, have made Bath so celebrated. He then spoke 

 of the probable connection between volcanoes and hot springs ; and 

 mentioned that such springs generally occur where volcanic agency 

 has caused a "fault," and also that they are of most frequent 

 occurrence in those districts where volcanoes are either active, or 

 have been so at a very recent geologic period. The quantity of 

 solid matter contained in the water of hot springs was alluded to ; 

 and it was said, that if the mineral ingredients contained in the 

 Bath waters were solidified, they would form, in one year, a square 

 column nine feet in diameter, and no less than 140 feet in height. 

 Although the waters of hot springs are, as a rule, destitute of the 

 common metals, such as iron, etc., there is a strong presumption 

 that there exists some relationship between the action of thermal 

 waters, and the filling of rents with metallic ores. The component 

 elements of metallic ores may, in the first instance, rise from great 

 depths in a state of sublimation, or of solution in intensely heated 

 water, and may then be precipitated in the walls of a fissure, as 

 soon as the ascending vapours or fluids begin to part with some of 

 their heat. It is possible that the metamorphism of sedimentary 

 rocks may also be owing to the influence of hot springs. The 

 thermal waters of Plombieres, in the Vosges, were conveyed by the 

 Romans to baths through long aqueducts. In this case, the hot 

 water percolating through the masonry has given rise to various 

 zeolites, — to calcareous spar, arragonite, fluor spar, and even opal. 

 It is possible that the consolidation of granite may have taken place 

 at less high temperatures than were formerly supposed ; and. the 

 manner in which volcanoes have shifted their position throughout a 

 vast series of geological epochs may, perhaps, explain the increase 

 of heat as we descend to the interior of the earth, without the 

 necessity of our appealing to an original central heat, or the igneous 

 fluidity of the earth's nucleus. Great changes within comparatively 

 recent periods have taken place in the climate, not only of Britain 

 but of the whole northern hemisphere. The probable causes of the 

 refrigeration of central Europe, during the glacial period, have to 

 do with the alterations in the physical geography of the surrounding 

 countries during that period. It has been shown that during that 

 time the Sahara, '—now a burning desert, sending hot winds, whose 

 effect is to lessen the extent of the ice on the Alps, — was a 

 sea, furnishing moisture. This moisture cooled on the Alps, pro- 

 bably at that period 2000 to 3000 feet higher than they are now, 

 would in great measure account for the ancient glacier- extension in 



