as observed at a Depth of 500 Yards, at Monk-Wearmouth. 449 



Each of the thermometers belonging to the party was 

 plunged in the bore-hole A, and the temperature was uni- 

 formly found about 70°, allowance being made for the differ- 

 ence of the graduation of the instruments. 



6. Mr. Wharton now caused excavations to be made in the 

 floor of the east drift to the depth of about nine inches, and 

 quickly inserted in each a minimum thermometer, previously 

 heated to about 75° — 80°, and left them for half an hour. The 

 temperature of the air near the surface of the floor at each point 

 was 62° to 63° ; that of the loose small coal on the surface 64° 

 to 67°. It was found upon two trials that at the point D, 

 nearest the pit, the temperature at this depth was 64°*5 ; 

 at C, further in, 66°*4 ; at B, six yards from the forehead, 

 69°*4 and 69°'9. We then chose a point near A, within two 

 or three yards of the forehead, and sunk the instrument 

 deeper, so that it was quickly surrounded by the gushing salt 

 water : when taken up it stood at 71°'4. 



7. We next determined to try the temperature of a fresh 

 face of coal, by picking off a few inches in depth, and placing 

 the thermometer in contact with the fresh face and its bulb 

 among the particles which had fallen. The first rough trial 

 gave 69°; the next a temperature continually rising till it 

 settled at 71i°. 



8. In trying again the temperature of the bore-hole A, we 

 observed that the thermometer fluctuated through a full de- 

 gree, being highest whenever bubbles of gas rose more rapidly 

 through the water, and lowest when these ceased for a while. 

 It was also found that this water, notwithstanding the effect of 

 human bodies, lights, &c, was continually cooling by the cur- 

 rent of air in the drift. At 2 p.m. its temperature was 69°*7 

 when air-bubbles rose in abundance, and 69°*1 when this was 

 not the case. Some time later it was again registered 69°*6 

 and 69°*3. 



Finding this to be uniformly the case, we returned to the 

 little pit near A, and found by a delicate thermometer the 

 temperature of the water when bubbles abounded to be 72°*6, 

 and 71°*6 and 72° # when they ceased. 



9. While these experiments were in progress, Mr. Whitley 

 caused a hole two feet six inches in depth, to be made in the 

 floor of the coal in the forehead of the west or rise drift F, 

 and in this he poured water at 56° Fahr., and then with parti- 

 cular precautions introduced a thermometer at 2 p.m. The 

 men were directed to abstain from entering this drift, till, on 

 Monday morning, after an interval of two days, Mr. Whitley 

 returned, and with Mr. G. Atkinson, drew out the thermo- 

 meter and found it to stand at 71°*2. As Mr. Whitley has 



Third Series. Vol.5. No. 30. Dec. 1834. SM 



