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 table comparing dial RPM readings, actual drive speeds, corrected dial readings and instrument error.
| Identifier | ExFiles\Box 160\4\ scan0114 | |
| Date | 21th April 1939 | |
| 1349. 21/4/39. | Dial Reading R.P.M. | Actual Drive Speed. R.P.M. | Correct Dial Reading. R.P.M. | Instrument Error. | |---|---|---|---| | 2,000 | 494 | 1,976 | + 1.22% | | 2,500 | 620 | 2,480 | | | 3,000 | 742 | 2,968 | | | 3,500 | 862 | 3,448 | | | 4,000 | 982 | 3,928 | + 1.86% | | 4,500 | 1,102 | 4,408 | + 2.09% | B.27 LE. | ||