Thank you very much to all those who've replied to my query with much
interesting information and some useful references. I can understand iron
ore being mined in this way as there's usually a lot of it, and prior to the
industrial revolution, bloomery sites produced only a few tons of iron a
year. One would imagine that someone would go for a few sackfulls every
month or so, and extensive workings and timbering would have been too
difficult to maintain.
In coal mines things usually seem to have been different. Observation
of some "bell pits" at Reagill near Penrith on an isolated little coal field
with a thin, poor seam but lots of lime kilns around, showed one very shallow
shaft where the outline of the workings appeared to be shown in subsidence
hollows. These appeared to showe 8 radiating passageways from the shaft,
with shallower depressions inbetween where presumably the coal had been
worked. The seam was 20-30 cm thick, the workings around about 1800, if my
local informant was correct. Shafts were in rows about 50-60m apart down the
sloping field, and 20-40m between pits in each row at the same level across
the field. Was the limit of working due to transport, poor ventilation,
drainage, or problems with working from the galleries with long tools to get
out the coal, or with propping the roof, or coping with subsidence as the
width between roadways increased? I'm pleased there is some evidence
elsewhere for radiating passages. Earlier workings on shallow but much
thicker seams may well have been worked by a series of closely spaced but
independent shafts. It would be less work to dig a new shaft than properly
support a gallery and move coal underground over ever longer distances, even
if the other problems of drainage and ventilation didn't limit activities.
Albyn Austin
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