ON UNDERGROUND TEMPERATURE. 17 



Temperatures Fahrenheit. 



NameofColHery. ^2tt S^^- ^J^. ''^ 



Marie 232 59° 78° 77° 



Do 310 .56 77 78 



Henri Guillaume 505 45 77^ 87 



The site of the two coUieries in question is on the banks of the Mouse. The 

 observations were made at the bottom of holes 5 centimetres in diameter and 

 5 metres deep, bored at the ends of galleries 6 feet high and G feet wide, 

 the material of the rock being coal-schist (des schistes houillers). The ther- 

 mometer remained in each hole twenty hours. The holes at the depths of 

 232 metres and 310 metres are almost vertically beneath the bed of the 

 river. The hole at the depth of 505 metres is about 900 metres from the 

 river. The coal-bearing strata are covered with 8 or 10 metres of gravel, in 

 which the bed of the river is contained. 



Comparing the first and last of the above observations, we have an 

 increase of 10° Fahi-. in 273 metres, which is at the rate of 1° Fahr. in 

 27-3 metres, or in 90 feet. 



The temperature of the ground near the surface can be approximately 

 inferred from Quetelet's observations at Brussels, which is about 50 miles 

 distant from Seraing, and about 10 miles further north. Quetelet found the 

 ground, both at the depth of 12 feet and of 24 feet, to have a mean annual 

 temperature of 12° Cent., or 53°-6 Fahr. If we accordingly assume at 

 Seraing a temperature 54° Fahr. at the depth of 5 metres, we have, by com- 

 parison with the temperature 87° at 505 metres, an increase of 33° in 500 

 metres, which is at the rate of 1° Fahr. in 15-2 metres, or in 50 feet. 



It was mentioned in the 1872 Report that four thermometers had been 

 sent to the School of Mines at BaUarat, Australia. A communication has 

 recently been received from the Vice-President (his Honour Judge llogers), 

 enclosing a report of observations taken at Clunes, in the mine of the IS^ew 

 North Clunes Company, by Mr. John Lewis (the Company's general manager), 

 and promising a report of observations from the Stawell Mine by an early 

 mail. Both mines are about 1000 feet deep. 



Mr. Lewis's observations were taken in twelve bore-holes, each 3 feet 

 deep, which were fiUed with water four or five hours previousl)'^, aud the 

 thermometer (a large non-registering mercury thermometer) was allowed to 

 remain in the hole for thirty minutes before reading. The depths from the 

 surface of the ground vary from 160 feet to 1015 feet. It appears that 

 sufficient precautions were not taken to exclude atmospheric influences, by 

 plugging the holes aud avoiding places where the currents of ventilation were 

 strong. The temperatures recorded in all the bores, except one, aj^pcar to 

 be thus vitiated, and are very variable from time to time. 



The one bore to which these remarks do not apply is designated " bore 

 No. 10," is at a depth of 790 feet from the surface, and is described as 

 " being in a cross cut without any circulation of air." The temperatures 

 observed in it, in the four observations recorded, were 72°-6, 72°-5, 72°-5, 

 and 72°-5, the temperature of the air in its vicinity being 73°- 6, 73°, 73°, 

 and 73°. 



Mr. Symons has furnished additional observations made at the depth of 

 1000 feet in the Kentish-Town well, but recommends that their publication 

 be deferred for the present, as better observations are expected during the 

 ensuing year. The hut which covers the well has been repaired, and the 

 1875. c 



