mining was the Dalton le Dale Pit, nine miles from Durham. On the 1st
June 1840 they pumped out 3285 gallons a minute. Engines were erected
which raised 93,000 gallons a minute from a depth of 90 fathoms or 540
feet, and this was done night and day. The amount expended to reach the
coal in this pit was £300,000. Mr. Hall estimates the capital invested
in the coal trade of the counties of Durham and Northumberland,
including private railways, waggons, and docks for loading ships, at
£13,000,000 sterling.

The great difficulty in working coal, should these upper seams fail, is
not only the increase of cost in sinking further down, but the increased
heat to be worked in. At 2000 feet the mine will increase in heat 28°,
at 4000, 57°; to this must be added the constant temperature of 50° 5',
so that at 2000 feet it would be 78° 5', and at 4000, 107° 5' Fahr. By
actual trial on July 17, 1857, in Duckingfield Pit, the temperature at
2249 feet was 75° 5'. From this it may be conceived in what great heat
the men have to work, and the work is very hard. One may fancy from this
what can be endured, but it would be next to impossible to work in a
greater temperature. I can speak upon this from actual experience, as
when down the Lady Londonderry Pit the temperature was 85°, and here the
men worked naked. Another great source of expense and anxiety lies in
keeping up the roof, as, from the excessive pressure, the roof and floor
are always inclined to come together, and props must therefore be used,
and these in some pits cost as much as £1500 a year. To digress for a
moment, an amusing story is told of Grimaldi, the celebrated clown, when
paying a visit to a coal-pit. Having gone some way through the mine, a
sudden noise, arising from the falling of coal from the roof, caused him
to ask the reason of the noise. "Hallo!" exclaimed Grimaldi, greatly
terrified, "what's that?" "Hech!" said his guide, "it's only a wee bit
of coal fallen down--we have that three or four times a day." "Then I'll