Aberdeen Harbour Board: Photograph of a page of a book showing a photograph of a piece of scientific equipment Equipment stored in wood and class case. Clock (marked "Harrison & Son Darlington") and thermometer at left end of case, larger piece of machinery - possibly water level recorder - on centre/right. Annotations around the image: "Dulton Lock", "Automatic water level recorder for both ends of lock" and "[illegible], 33 feet long self ruling". nd