Mike, although I don't know figures, a lot of the mines in Cornwall had drys a long time ago. Two of the most well known ones were Dolcoath, which was actually heated with the condensate from the man engine on Harriett shaft, part of the pipe is still in existance, tho other is bottalack where the bath is still in situ. Croftys old dry was pulled down last year to make way for the heartlands project. Its hard to believe any large mine in the last 100 years wouldn't have had a dry, as the benefit to the mines themselves from improved health of the miners would have been huge.