Sinclair Cambridge pocket calculator, by Sinclair Radionics Limited, Cambridgeshire, England, 1973 Sinclair Cambridge pocket calculator Computing & Data Processing 1973
Three Dowty Retarders, exploded to show mechanisms, 5 foot/second retarder, 4 and 12 foot/second booster retarders, in display case, British Railways, c1967, fitted to track in marshalling yard and used to speed or slow wagons during marshalling. Demonstration "Dowty" retarder Railway Infrastructure 1967