I have questioned the bell pit theory for some time, particularly  since I
studied the Brampton Coalfield in East Cumberland. I was fortunate enough to
dig up quite a few early 18th cent engineers reports on these pits which
helped explain many things, as they usually included (rudimentary) plans.

Records existed of mining during the second decade of the 17th cent, though
no plans of these were found, the areas worked could be located on plans of
collieries reworking the ground during the 19th cent.

The usual method of working in these parts was to sink an engine shaft for
water drawing, around 1725-30 the max depth they could drain with the bob gin
was 8 fathoms. 2 levels were taken; the water level from the bottom of the
engine shaft with a coal drawing level driven parallel, 5-10 yards to the
rise. Coal drawing shafts were driven along this level. As the workings
advanced the cost of haulage (draggage) got to high  (see complete collier
for more detailed account of distances/prices ect) so another shaft was sunk.
The amount of coal and life span which could be worked via any given pit was
calculated by the engineers; During 1871 at Blenkinsopp colliery, the shaft
to supersede the John pit was calculated to last 5 years. The expense to sink
this shaft over 360 feet was deemed non viable so a whole new colliery was
set out near Angerton.

All of this research and visiting sites full of what would be termed 'bell
pits' brought the theory into doubt, as did reading of 14th and 15th cent
mining on the continent. If one thinks also of the practicalities of mining
in conjunction with this bell pit method we also have to question it's so
much described wide spread adoption;

 Relatively shallow reserves worked (re practicality of Blenkinsopp shaft for
5 years, and not a few months as in a bell pit). Depending on types of rock
which forms roof of coal seam sandstones obviously excepted; In shales the
roof conditions at shallow depths are usually bad and anything but self
supporting. In an average seam of say 4'6" the average daily advance by a
hewer is normally at least 1 yard forwards on a face of 2 yards width thus in
a 6 day week giving an advance of at least 6 yards in one direction.

Taking the fact that there is only one hewer in a month he would have
extracted 6 yards in 4 directions from the bottom of the shaft.Even if he
spent a further week on each of the pillars he would have extracted a 'ball
room' within 2 months which in my opinion would have collapsed in normal
shales well before he had time to do even this. Even using timber supports
great weights would soon be encountered by this total extraction. The only
solution would be to work away from the pit bottom leaving pillars to support
the shaft bottom, and then the roadways.....Conventional working and not bell
pit theory.

When pillaring and working in broken roof with great weights working on the
strata, a collier has little time to decide when it is time to abandon the
bord and get back bye before the lot comes in. If the shaft was also in
danger of collapse his opportunity for escape would be non existent, either
that or he would be up and down the shaft like a yoe yoe every time the roof
was working and making a noise. Also with complete collapse all the gear
would be lost... Not practical and even during medieval times you couldn't
kill miners en mass...they would all take up baking or some other safe
operation.

My conclusions were the practicalities of this method of working were non
existent. Not that I am saying it never took place, rather if it did it was
not because mining had not evolved beyond this practice, rather for other
reasons and I believe the practice could only be isolate,certainly amongst
shales at any rate.

Clive Seal