International Slide Rule Museum...62/6 EACH D. 1.5* Dualistic High Speed 14/- each with log-log...
9
International Slide Rule Museum...62/6 EACH D. 1.5* Dualistic High Speed 14/- each with log-log scales 9/6 each D-2.5" Dualistic High Speed D.3.lO" Dualistic High 23/- each Speed 27/6