Ms, [4] leaves on one sheet. 'On the Washing of Lead Ore' / Lead Mining, Alston Moor, Northumberland, early 19th century. unsigned. no watermark. 25 x 38cm folded to 25cm x 19cm. In the same hand as titles to watercolours and sketches. Contemporary account of practice and the potential of a machine, based on personal survey 'I collected and determined....'; proposes a vessel for the washing and removal of lead ore from water with control over velocity; refers to figurations in accompanying sheet (No. 67).