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).
Calibration figures for A.T. Speedometer No. 527.
| Identifier | ExFiles\Box 59\2\ Scan142 | |
| Date | 23th March 1932 guessed | |
| CALIBRATION FIGURES OF A.T. SPEEDOMETER No. 527. | Speed Indication on Dial. | Revolutions per min. of shaft. | Correct M.P.H. | Percentage Correction. | |-----------------------------|--------------------------------|----------------|------------------------| | 10 | 137 | 10.5 | 5% fast. | | 20 | 274 | 21.00 | 5% fast. | | 30 | 396 | 30.39 | 1.3% fast. | | 40 | 525 | 40.25 | 1.1% fast. | | 50 | 646 | 49.50 | 1.0% slow. | | 60 | 770 | 59.00 | 1.6% slow. | | 70 | 897 | 68.90 | 1.6% slow. | | 80 | 1016 | 77.89 | 2.6% slow. | | 90 | 1147 | 87.87 | 2.4% slow. | | 100 | 1260 | 96.50 | 3.5% slow. | 784 revs per mile according to our calibration. | ||