92 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



UNDERGROUND TEMPERATURE. 



The report of the British Association Committee on Under- 

 ground Temperature, by Professor Everett (Nature, vol. 

 xvii., p. 470 ; American Journal of Science and Arts, III., 

 xvi., p. 134), gives results of observations, on a very elaborate 

 scale, at Schemnitz, in Hungary, and also in England and in 

 India. The former series was undertaken ill response to a 

 request from the Secretary, in 1873, to the Imperial School 

 of Forests and Mines at Schemnitz, and was carried out by 

 Dr. Otto Schwartz. It consisted of observations in no less 

 than thirty-eight galleries connected with six shafts of the 

 mines. Comparisons were made between the temperature of 

 the deepest gallery of each shaft and the assumed mean an- 

 nual temperature of the ground at the shaft-mouth, and also 

 between the deepest and the shallowest observation in each 

 mine. The result of the former was an average increase of 1C. 

 for 41.4 meters, or 1 Fahr. for 75.5 feet; of the latter 1 C. 

 for 39.8 meters, or 1 Fahr. for 72.5 feet. The mean of these 

 two would be 1 Fahr. in 74 feet. The report brings out inci- 

 dentally the important variations of rock temperature, which 

 may arise from the decomposition of metallic sulphides as 

 pyrites, the disturbing effect of which needs to be guarded 

 against. The English observations were made at Boldon 

 Collierv, between Newcastle and Sunderland, in two holes 

 bored upward to a distance of 10 feet from some of the deep- 

 est seams. The results indicated, for the interval between 

 the two holes, a rate of increase of 1 Fahr. in 3 7 feet; and for 

 the whole depth from the surface a rate of 1 Fahr. in 49 feet. 

 The Indian observations, published in the JRecords of the Ge- 

 ological Survey of India, vol. x., part i., were made in 1875, 

 under very satisfactory conditions, in a bore 310 feet deep, 

 at a place named Manegaon. The results indicate an average 

 increase of 1 Fahr. for G8 feet. 



Professor Everett has suggested a method of observing 

 temperature in filled-up bores by a sort of modified thermo- 

 pile. Two wires of different metals as iron and copper hav- 

 ing been joined at both ends and covered with gutta-percha, 

 except at the junctions, were to be placed with one junction 

 buried in the bore, and the other above ground. Then a gal- 

 vanic current would be generated in the wire whenever the 



