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).
Table recording the results from trials of a speed indicator tester.
| Identifier | ExFiles\Box 33\5\ Scan081 | |
| Date | 17th May 1926 | |
| TRIALS OF SPEED INDICATOR TESTER. Date. | Approx. time period. | Time under 10 mins. for 3000 counter revs. (secs) | % fast. | Frequency. 8-4-26 | 2-0 to 2-10 | +1.6 | +.27 | 50.13 9-4-26 | 10-0 to 10-10 | +3.7 | +.62 | 50.31 9-4-26 | 3-0 to 3-10 | +1.8 | +.30 | 50.15 10-4-26 | 11-0 to 11-10 | +2.2 | +.27 | 50.13 14-4-26 | 10-0 to 10-10 | +3.0 | +.50 | 50.25 14-4-26 | 13-0 to 3-10 | +1.4 | +.23 | 50.11 15-4-26 | 11-0 to 11-10 | +1.7 | +.28 | 50.14 15-4-26 | 4-0 to 4-10 | +1.0 | +.14 | 50.08 16-4-26 | 12-0 to 12-10 | +1.1 | +.18 | 50.09 16-4-26 | 5-0 to 5-10 | +2.8 | +.47 | 50.23 17.5.26. | ||