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).
Graph comparing the performance of four different car heaters over time.
| Identifier | ExFiles\Box 137\3\ scan0260 | |
| Date | 3rd February 1938 | |
| FIG 2 B. THERMOMETER ON FRONT FLOOR CLOSE TO DIP SWITCH. C. THERMOMETER IN CENTRE OF REAR SQUAB 1. HADEES HEATER WITH LONG SHIELD 2. HADEES HEATER WITH SHORT SHIELD 3. HADEES HEATER WITHOUT SHIELD 4. A.C. HEATER TEMPERATURE ABOVE OUTSIDE AIR IN DEGREES CENTIGRADE TIME FROM START OF TEST IN MINUTES 1B 2B 3B 4B 1C 2C 3C 4C RM{William Robotham - Chief Engineer}/Clim 3-2-38 | ||