On Underground Temperatures. 



13 



in the npcast shaft, 7^ feet in diameter, of another pit, 150,000 cubic 

 feet of air passed per minute. 



At the Hetton Colliery (No. 116), Durham, the dependence of the 

 temperature of the strata upon distance from the shaft, in connexion 

 with ventilation, is well shown in a table by Mr. Wood, of which the 

 following is an abstract. 



Surface temperature at date = 36°. Holes in coal 3 feet deep. 



Depth 

 from sur- 

 face. 



Distance 

 from shaft. 



Cubic feet 



of air 

 per minute. 



Temp, 

 of coal. 



Temp, 

 in current 

 of air. 



Rate of 

 increase in 

 depth for 

 1° F. 



1100 feet 



312 yards 



104,000 



60° 



50° 



100 feet 



1270 „ 



915 „ 



50,000 



63 



58| 



91 „ 



1360 „ 



1640 „ 



18,600 



66 



62 



80 „ 



1354 „ 



3664 „ 



3,200 



68 



68^ 



67 „ 



1400 „ 



3550 „ 



4,972 



70^ 



72 



64 „ 



1395 „ 



4332 „ 



5,000 



71 



73 



63| „ 



In this case we have four observations made nearly at the same 

 depth, and yet showing a rate of increase with depth varying from 

 80 feet to feet for 1° Fahr. 



In the Seaham (Durham) Colliery the circulation of air is very 

 large, — 193,346 cubic feet per minute. At a depth of 1524 feet and 

 1642 yards distant from shaft, the temperature of the air was found 

 to be 61° : at 2726 yards distant and at the same depth it was 67°; and 

 at the face of the coal 82°. The temperature of the return air=76^-°. 



At the Eppleton Colliery, Durham, in October (?) the temperature 

 of the air at the intake at a depth of 850 feet and 110 yards distant 

 from shaft was 44°, and after circulating 1960 yards, 59J°, or an 

 increase of 15-^°. 



Some joint observations by Mr. Wood and Mr. Dickinson in the 

 Monkwearmouth Colliery (No. 30), Sunderland, gave the following 

 results. 29th March, 1870. Temperature of surface = 42°. 



Depth. Distance from shaft. Temp, of the air. 



1676 feet Bottom of down shaft 50° F. 



1676 „ .... 2134 yards .... 66 „ 



1638 „ 2850 „ 74 „ 



1646 „ .... 3112 „ .... 81 „ 



1640 „ .... 4030 „ .... 82 „ 



This pit is so dry that it requires water to lay the dust. 



Mr. Dickinson found that at a depth of 2088 feet iu one of the 

 Pendleton pits the temperature at 500 yards from the engine brow 

 was 78°, and at 1000 yards distant 82°. In the same pit at a depth 

 of 2214 feet and distant 200 yards from the engine brow, the coal in 



