Keuffel & Esser N4041 10 in Mannheim slide rule in a black leather on cardboard case with flap and stud fastener (c.1930). Equivalent tables on reverse. It is a generic slide rule with scales A and D on the stock and B and C on one face of the slide, with scale S,L and T on the reverse side representing cine, logarithm and tangent respectively.
The slide rule was passed down to the donor from her grandfather Alec Gilbertson FICE FIMechE who was a chartered civil and mechanical engineer with world-wide experience. To see a copy of his extensive CV click here.