194 report — 1877. 



Tenth Report of the Committee, consisting of Prof. Everett, Sir W. 

 Thomson, F.R. S.j Prof. J. Clerk Maxwell, F.R.S.,G. J. Symons, 

 F.M.S., Prof. Ramsay, F.R.S., Prof. A. Geikie, F.R.S., James 

 Glaisher, F.R.S., W. Pengelly, F.R.S., Prof. Hull, F.R.S., 

 Prof. Ansted, F.R.S., Prof. Prestwich, F.R.S., Dr. C. Le 

 Neve Foster, F.G.S., Prof. A. S. Herschel, F.R.A.S., G. A. 

 Lebour, F.G.S., A. B. Wynne, F.G.S., W. Galloway, and 

 Joseph Dickinson, F.G.S., appointed for the purpwse of investi- 

 gating the Rate of Increase of Underground Temperature doivn- 

 ivards in various Localities of Dry Land and under Water. 

 Drawn up by Prof. Everett, Secretary. 



Observations on a very elaborate scale have been received from the important 

 mining district of Scbemnitz, in Hungary. A request for observations was 

 sent by the Secretary in 1S73 to the Imperial School of Forests and Mines 

 at Schemnitz ; and, on the receipt of two thermometers, a Committee was 

 formed to plan and carry out observations. The leading part in the ob- 

 servations has been taken by Dr. Otto Schwartz, Professor of Physics 

 and Mathematics, who has furnished an elaborate Report of the results 

 obtained. This is accompanied by a geological Report drawn up by Pro- 

 fessor Gustav von Liszkay, and by a geological map with plans and sections 

 of the mines. 



The two thermometers sent being deemed insufficient for the numerous ob- 

 servations which were eomtemplated, 25 large thermometers were ordered 

 from a local maker (T. T. Greiner), and the 10 best of these, after being 

 minutely compared with one of the two thermometers sent (which was non- 

 registering, and had a Kew certificate), were devoted to the observations. 

 Three of them were divided to tenths, and the others to fifths of a degree 

 Centigrade, and all had bulbs of thick glass to ensure slowness of action. 

 They were found not to change their indications during tLc time requisite 

 for an observation. 



The observations were, for the most part, taken by boring a hole in the rock 

 to a depth, in the earlier observations, of -422, and in the later ones of -70 

 of a metre, then filling the hole with water, and, after leaving it, in some cases 

 for a few hours, in others for several days, to plunge a thermometer to the 

 bottom of the hole, and after 30 or 45 minutes take it out and read it. The 

 tenths of a degree were read first, and there was time for this to be done before 

 the reading changed. As a rule, three observations were taken in each 

 gallery, two of them in bore-holes to give the temperature of the rock, and 

 the third in the air of the gallery at an intermediate position. Pyrites and 

 also decaying timber were avoided, as being known to generate heat ; and, 

 as far as possible, currents of air and the neighbourhood of shafts were 

 avoided also. 



A table which forms part of Dr. Schwartz's Report contains observations 

 made in no fewer than thirty-eight galleries. Besides the temperatures, it 

 gives the depth of the place of observation beneath the shaft-mouth, and the 

 height of the latter above sea-level. Dr. Schwartz takes exception to a few 



