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).
Test results for an A.T. Speedometer (14-EX) showing MPH readings at various temperatures.
| Identifier | ExFiles\Box 50\4\ Scan152 | |
| Date | 19th November 1927 | |
| X4308 19.11.27. X A.T. SPEEDOMETER (14-EX). 728 Temp. M.P.H. at 600 r.p.m. 18°C 45.1 18°C 44.9 20°C 44.3 22°C. 43.3 24 C. 42.1 26°C. 42.0 28°C. 41.3 30° C. 40.8 32° C. 40.3 34°C. 39.6 Initial observations taken at end of 30 mins. (for warming up of disc) At full speed of 1200 r.p.m. reading is 79.0 m.p.h. at 34°C. EFC. {E. Fowler Clarke - Electrical Engineer} EFC. {E. Fowler Clarke - Electrical Engineer} Speedometer should read 47 M.P.H at 600 R P M | ||