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David Thanks for the reply. It tends to confirm my view that Shrewsbury Colliery Company, Limited was not all it should have been, they were offering shares for sale in mid September 1874 and in voluntary liquidation by the end of that year. They held a lease at Asterley for 183 acres with a further 75 available, they also said that they might acquire 170 acres of land at Nobold . The land in Asterley had had a series of mines active since the early 18th century, the land at Nobold had been considered worked out by 1840 there would not have been much coal left under either. Seasons greetings to all Mike Shaw ----- Original Message ----- From: "David Williams" <[log in to unmask]> To: <[log in to unmask]> Sent: Sunday, December 18, 2011 6:51 PM Subject: Re: [mining-history] coal > My Guess > > According to the Internet unbroken bituminous coal has a weight of 84lbs > per > cubic foot. > > This is more or less one ton per cubic yard > > Therefore we are looking at 2,280,000 cubic yards. > > At 4ft 6ins thick we are looking at 1,520,000 square yards of solid coal. > > One acre is 4840 square yards. > > Therefore a solid area of coal weighing 2,280,000 tons at 4ft 6ins thick, > would occupy 314 acres. > > You would now have to factor in what the extraction rate is? I suspect > that > 30% would be something like. This would give around 1050 acres. There are > 640 acres in a square mile - giving an area of 1.64 square miles. > > At the end of the day it all depends on extraction rates - losses due to > faulting, bad coal, pillars etc. > > Hope this helps. > > Dave. > > -----Original Message----- > From: mining-history [mailto:[log in to unmask]] On Behalf Of M > J > Shaw > Sent: 18 December 2011 18:28 > To: [log in to unmask] > Subject: coal > > The Hanwood coalfield around Shrewsbury had three seams of coal, the Yard, > Half Yard and Thin whose total thickness rarely achieved 6 foot. Is anyone > willing to hazard a guess as to how many acres (square miles?) would need > to > be mined in the late 19th century, assuming uniform seam thickness, to > extract 2,280,000 tons from just the first two of these seams, four feet > six > inches max in total, over 21 years. > Michael Shaw