Details
An ebony and ivory roller rule,
by L. Barbe & Co 60 Regent Street London -- 12¼in. (31cm.) wide; and ivory-mounted slide rule, by L.P. Casella; an electrum-mounted folding ivory two foot rule with extending gauge, by Millward Birmingham, engraved on the hinge plate A.H. Bampton Plymouth; another slide rule; and five ivory scale rules (A Lot)
by L. Barbe & Co 60 Regent Street London -- 12¼in. (31cm.) wide; and ivory-mounted slide rule, by L.P. Casella; an electrum-mounted folding ivory two foot rule with extending gauge, by Millward Birmingham, engraved on the hinge plate A.H. Bampton Plymouth; another slide rule; and five ivory scale rules (A Lot)