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).
Comparing the performance and cost of Ferranti and Weston ammeters for use in Bentley vehicles.
| Identifier | ExFiles\Box 168\5\ img311 | |
| Date | 28th December 1934 | |
| Roy{Sir Henry Royce}/MS. From Ha/Wst. Ha/Wst.11/MA.28.12.34. AMMETERS. Replying to your Roy{Sir Henry Royce}/MS.11/P.27.12.34., the Ferranti ammeter with the 30 ampere range, which is the latest experimental version, is fitted to the Bentley for the 10,000 mile test which has not yet started due to hold ups on other items. Bench tests on this Ferranti ammeter are satisfactory but not superior to the Weston. With regard to the last paragraph of your memo the position regarding the Weston ammeters, we have ascertained, is not so serious as might be understood from your statement. Of all the Weston ammeters both new and fitted to Customers cars, 40/50, 20/25 and Bentley, only on the average one ammeter per week is returned for all complaints and the Weston is a considerably cheaper instrument than the Ferranti. Ha/Wst. | ||