Fahr. 
136 Mr Bald on the Temperature of Ah' and Water 
Jarrow Colliery . — County of Durham- 
Air at surface, 491'' 
Water at the depth of 882 feet from the surface, 68* 
Air at same depth, 
Air at the pit bottom, 64* 
Difference betwixt tlie average temperature of v/ater at the 
surface 49°, and water at the depth of 882 feet, 19* 
The engine pit of Jarrow is the deepest perpendicular shaft 
in Great Britain, being 900 feet to the foot of the pumps. 
Killing^vortli Colliery.— -Covvoty of Northumberland. 
Air at the surface, 48* 
Air at the bottom of tlie pit, the depth being 790 feet, 51® 
Air at the depth of 900 feet from the surface, after having 
traversed li mile from the bottom of the downcast pit, 70* 
Water at the most distant forehead or mine, and at the 
great depth of 1200 feet from the surface, 74* 
Air at the same depth, 77* 
Difference betwixt the average temperature of w^ater at the 
surface 49°, and water at the depth of 1200 feet, 25* 
This mine is the deepest coal mine in Great Britain from 
X. 
the surface, although Jarrow is the deepest perpendicular 
shaft ; in this mine the temperature of distilled w^ater at 
the boiling point was 213* 
Temperature of same water at the surface, 210^* 
Prince’' s-end Pit^ near Tipton, Staffordshire. 
AVater at the bottom of the engine pit, above 400 feet deep, 47^* 
Air in the mines, 60* 
It has been found from experience, that the deeper -we perfo- 
rate the strata, they become drier, and in miany instances no water 
is to be found, so that the roads through the mines require to be 
W'atered in order to prevent the horse-drivers from being annoyed 
by the dust ; and there is reason to believe, that the high tempe- 
rature of the air in Prince’s-end pit, was occasioned by the decom- 
position of pyrites amongst the rubbish of the coal, which fre- 
quently produces actual and vehement combustion. The in- 
c*rease of temperature, as given in the preceding experiments. 
