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).
Preventing pip formation in electrical contacts by reversing current.
| Identifier | ExFiles\Box 35\6\ scan 116 | |
| Date | 22th February 1924 guessed | |
| -2- P.C.20. The formation of a pip could probably be eliminated by reversing the current through the points periodically, but the trouble appears in the first place to be due to insufficient contact surface area. CAP. | ||