The obvious difference between the remains you'd see for a cog and rung and a whim gin is having the horse walk around the shaft instead of to one side of it. I realise it's a long shot for survival of old stuff in the main coalfields due to re-use of sites and land improvement but you never find out unless you ask knowledgeable people! John Barnatt's been looking at the collieries of the east and west moors in the Peak (large Mining History article in preparation!), I know about Thatch Marsh through him and there's apparently another site with possible cog and rung gins at Ollerenshaw, but he's not seen any on the Eastern moors to date.
Going back to Jim Rieuwerts for a moment, he's pulled quite a few references from the Duchy and Chancery court records at the PRO to use of horse gins in the Peak around the 1630s, also to use of rag and chain pumps but irritatingly nothing that definitively states that there were horse-powered rag and chain pumps. The nearest thing is a reference to the 1630s Dovegang pumping where a witness commented "there were some that went with the power of horses". Mind you, there's also a really bizarre reference to someone trying to drain the gang mines with glass tubes at this time, which I'm sure will get a mention in vol. 4.... :blink:
Follow the horses, Johnny my laddie, follow the horses canny lad-oh!