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 record for an A.T. Speedometer, detailing performance at various temperatures.
| Identifier | ExFiles\Box 59\2\ Scan045 | |
| Date | 9th July 1930 | |
| X4308 A.T. SPEEDOMETER TEST RECORD. Date :- 9-7-30 Speedometer :- AT. No D.668.765. 1/41. Remarks :- Gff 19 EX 47.1 Counter revolutions per mile 764.9 (Found by actual trial). Miles per hour indicated at 600 r.p.m. exactly :- Temperature (°C) | M.P.H. indicated. | Revs. per mile. of drive for correct speed reading. 20.0 | 47.7 | 754 22.0 | 47.5 | 758 24.0 | 47.3 | 761 26.0 | 47.1 | 764 28.0 | 47.0 | 766 30.0 | 46.8 | 769 32.0 | 46.7 | 771 35.0 | 46.5 | 774 Percent fall of reading between 20°C. and 30°C. : 1.9...... S.7.30. | ||