Cross-reference note for further information on the 40/50 switchbox.
| Identifier | ExFiles\Box 65\2\ scan0063 | |
| Date | 31th December 1930 | |
| X.7730 31.12.30. For further matter relating to 40/50 switchbox (general) see X.6070. | ||
From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).