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).
Scheme for a red warning light to indicate when the engine's water is nearing boiling point.
| Identifier | ExFiles\Box 175\4\ img050 | |
| Date | 20th October 1926 | |
| 43875 S/W Hs.{Lord Ernest Hives - Chair} C8/C20.10.26. Will you kindly let me know if you have been able to get through a sbheme whereby drivers are warned, by means of a red light, when the water in the car is getting near boiling point. C. | ||