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 standardization of Ferranti Ammeters following test results.
| Identifier | ExFiles\Box 168\5\ img192 | |
| Date | 22th July 1930 | |
| X3498. To BY/Cgh.{W Clough} from EFC. EPC1/BE22.7.30. X.3498. Ferranti Ammeters. Answering your BY/Cgh{W Clough}16/G17.7.30. the Ferranti Instruments Nos. 32352-6, upon the results of tests of which these ammeters have been standardised, were ordered to our Drawing No. P.75652 in our standard patch finish and supplied with metal covers. EFC. | ||