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).
The magnetic screening of ammeters and petrol gauges.
| Identifier | ExFiles\Box 59\2\ Scan383 | |
| Date | 12th January 1934 | |
| will affect any instrument which is not magnetically screened when six inches away. The screening of the ammeter and petrol gauge will affect the calibration slightly. | ||