Engineering Drawing - James Watt; General Section of Wanlockhead Engine; Sheet No.1; Jun 1785; Hand-coloured ink and watercolour drawing showing a general cross-section of an atmospheric condensing beam pumping engine designed by James Watt and supplied by the firm Bolton & Watt; of Birmingham; to the Margaret Mine; at Wanlockhead; Dumfries; Scotland; in 1785-86. Scale: 1/3 inch to 1 foot. The drawing is part of a set of technical drawings supplied by the manufacturers showing general