The Excavation of a Bell Pit
The miners chose a place where the coal seam was near the surface. This was probably located from the previous excavation of a surface coal seam. A vertical shaft was dug from the surface until it reached the seam with the soil encountered during the fist few feet being held back with wooden boards. The shaft was just large enough for a person to be lowered and for material to be hauled out.
Once the seam was reached, miners dug horizontally outward in all directions, forming a bell-shaped cavity. The shape was widest at the bottom and narrower at the top, like an upside-down bell – hence the name bell pit. The cavity was unsupported, so miners could only dig as far as the ground above remained stable.
Extracted material was lifted up using buckets and ropes, often by hand or with a basic winch.
Once the roof became unstable the pit was abandoned. A new bell pit would be excavated nearby, sometimes just a few meters away with the rubble from the second pit being dumped into the first. This often leaves the landscape dotted with shallow depressions the remnants of former pits which show, on the surface, the direction of the underground coal seam.
Cross Section of a Bell Pit
The depression left in a field after the Bell Pit has been backfilled
Photograph – Alan Gray (2005).
Mining before 1754
Source – A Brief History of Coal Mining in Clutton by L. J. Cunningham. Published by the Clutton History Group.
"It is most likely that bell pits were used extensively in Clutton before the 1610 mines. Indeed there are numerous mounds in the fields around Clutton and old workings have been found in Greyfield Wood, in Coalpit Field at Frys Bottom and behind Maypole Farm. The bell pits would have worked the coal seams that outcropped near to the surface. scale of production of the 1610 pits was small. Pits worked two at a time and employed two or three men underground, four or five carting boys and two or three men to wind up the coals using a simple windlass and bucket. The mines probably served a very limited local market.
Wages in 1610 were 14s. a week for a hewer and 1s 6d. a week for carting boys. Coal was sold for 3d per horse load which gave a pithead price of 1- 1½id. per bushel. Total costs, including candles, rope, timber and wages came to £3 per week. The net gain was £4 10s. , three quarters of which went to the lord.
Mining continued during this period for there are coal pit accounts dated 1663 – 1671 and 1681 – 1691 in the Earl of Warwick's estate records. There are also mining leases dated 1688 –1694, 1739 and 1752. The 1663 – 1671 accounts are mainly about money but it is possible to obtain some general information from them. This period appears to have been one of quite intense activity for there were 37 pits sunk. The field evidence for many of these pits must have disappeared many years ago, but it is most likely that the shafts in the Pennyquick, North End and Nap Hill areas date from this
era. The number of men employed varied between 10 and 16 each week and different men worked on successive weeks. Wages varied on a weekly basis, for example Thomas Naish Snr. was paid 10s 8d, 7s, 4s 8d, 5s 8d and 2s 10d for five different weeks in November and December of 1669. Probably the techniques used in these mines were very similar to those used in the 1610 mines."
While walking in Greyfield Wood, after the Woodland Trust had undertaken a large tree felling exercise, approximately 80 Bell Pits were identified in the wood and adjacent field
Lidar scan showing the Bell Pits on Greyfield Wood and surrounding fields as shadows (about 150 pits)
The Bell Pits but with an over lay showing the underground coal seams
Light Detection and Ranging (LIDAR)
The Lidar signal can be used to detect features buried under flat vegetated surfaces especially when mapping using the infrared spectrum. Lidar scanning units fire hundreds of thousands of laser pulses per second, from an aeroplane. The sensor uses the time it takes for each pulse to return to calculate distance. Each of these measurements, can be processed into a 3D visualisation.