Dubilier capacitance electrical engineer's slide rule, designed by Philip R. Coursey and manufactured by John Davis & Son (Derby) Ltd., 1928. Used from new by Mr A.E.Bennett chief engineer at Dubliers, electrical component manufacturers at Park Royal West London. Dubilier capacitance electrical engineer's slide rule 1928
Electrical engineering slide rule, Elecktro model 1/98 by A. W. Faber-Castell, Germany in cardboard case with instructions. Electrical engineering slide rule 1960-1965
Pickett slide rule, model N-16-ES, with electronics scales designed by Chan Street, Los Angeles, in leather carry case Pickett slide rule
Nelson-Jones circuit designer's (10-inch) slide rule, designed by Key Electonics Bownment and made by Blundell Harling Limited with plastic sleeve Nelson-Jones circuit designer's (10-inch) slide rule 1970-1975