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).
Scale calibration data for an A.C. Speedometer, Instrument No. II.
| Identifier | ExFiles\Box 165\2\ img106 | |
| Date | 13th July 1937 | |
| 6011 6 BIV 13.7.37. A.C. Speedometer. Scale Calibration :- Instrument No.II. Revolutions per minute of drive shaft | M.P.H. reading on dial. | Correct M.P.H. based on revs. per mile. | Percentage error. Fast | Percentage error. Slow 170 | 10 | 10.0 | - | - 350 | 20 | 20.5 | | 2.44 517 | 30 | 30.4 | | 1.32 657 | 40 | 38.6 | 3.63 | 820 | 50 | 48.2 | 3.74 | 990 | 60 | 58.2 | 3.10 | 1150 | 70 | 67.5 | 3.70 | 1320 | 80 | 77.5 | 3.23 | 1485 | 90 | 87.3 | 3.09 | 1650 | 100 | 97.0 | 3.09 | Remarks :- R.{Sir Henry Royce} = 1,022. Fitted to chassis No. | ||