President's Address. 



117 



small streams disappeared and afterwards burst out afresh 

 during the shock from an earthquake, forming springs 

 whose temperature in 1803 was 158° Fahr. It is worthy of 

 remark that in 1832 Mr Bullock found the heat of these 

 springs to be only a little above the temperature of the 

 climate. The hottest springs in South America were found 

 by Humboldt to contain the smallest amount of mineral 

 matters in solution. Their temperature, however, would 

 appear to be less constant than those of Europe, with a 

 temperature ranging from 122° to 165° Fahr., which have 

 undergone no change during the present century — that is 

 to say, since the application of scientific research by means 

 of the thermometer and by chemical analysis; whereas 

 Humboldt found those of Las Trincheras to increase 12° 

 in twenty-three years. Hot springs, then, show that a 

 heating cause does exist deep in the earth's crust ; and 

 their wide distribution tends to prove the wide distribution 

 of that cause, whatever it may be. 



V. The Increase of Temperature in Mines in 'proportion 

 to their Depth, and in the Water flowing from Borings made 

 for Artesian Wells,— This argument is of modern date, and 

 has a much higher scientific value than any of the others. 

 It seems to have originated with Gensanne, who first 

 applied the thermometer to this investigation, and ascer- 

 tained the important fact that the temperature really in- 

 creases with the depth. His experiments began in 1740, 

 and were carried on in the lead mines of Giromagny, 

 near Befort, to a depth of 1420 feet. Subsequent observa- 

 tions were made by Saussure in the deserted galleries 

 of an excavation which had been made at the salt-works 

 of Bex, in Switzerland. Humboldt and Freiesleben made 

 numerous experiments in 1791, in the Freiberg mines ; 

 and the former observer, during his travels in South America, 

 experimented on the temperature of mines to the depth of 

 1713 feet. Similar observations were made in Saxony by 

 Daubuisson and Trebra, and in the lead and silver mines of 

 Brittany ; and in our own country by Messrs Bald, Dunn, 

 and Fenwick, in the coal mines of the north of England, 



