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, showing readings at various temperatures.
| Identifier | ExFiles\Box 59\2\ Scan033 | |
| Date | 27th May 1930 | |
| X4308 X.4308. A.T. SPEEDOMETER TEST. 27-5-30 Speedometer No. E.187.785 1/41 Speedometer type 40/50 H.P Other particulars Taken from stock 45.8 Temperature (°C) | Miles per hour indicated at 600 R.P.M. exactly. | Revs. per mile of drive for correct speed reading. --- | --- | --- 20.0 | 45.9 | 784 22.0 | 45.8 | 786 24.0 | 45.7 | 787 26.0 | 45.5 | 791 28.0 | 45.5 | 791 30.0 | 45.4 | 793 32.0 | 45.4 | 793 35.0 | 45.4 | 793 Miles per hour at 1200 R.P.M. 3.6.29. EFC. | ||