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).
Data log sheet recording the results from trials of a speed indicator tester.
| Identifier | ExFiles\Box 33\5\ Scan079 | |
| Date | 18th March 1926 | |
| TRIALS OF SPEED INDICATOR TESTER. & Date. | Approx. time Period. | Time under 10 mins. for 3000 counter revs. (secs). | % Fast. | Frequency. --- | --- | --- | --- | --- 5.3.26. | 3.40 to 3.50 | + 2.6 | + .43 | 50.2 5.3.26. | 3.55 to 4.5 | + 1.2 | + .20 | 50.1 " | 4.42 to 4.52 | + 1.8 | + .30 | 50.1 8.3.26. | 11.0 to 11.10 | -1.0 | - .17 | 49.9 " | 11.40 to 11.50 | + 2.2 | + .37 | 50.2 " | 1.40 to 1.50 | + 1.7 | + .28 | 50.1 " | 2.10 to 2.20 | + 2.0 | + .33 | 50.2 " | 4.35 to 4.45 | + 1.8 | + .30 | 50.1 17.3.26. | 3.30 to 3.40 | + 2.2 | + .37 | 50.18 " | 3.45 to 3.55 | + 3.0 | + .50 | 50.25 " | 4.0 to 4.10 | + 3.0 | + .50 | 50.25 " | 4.25 to 4.35 | + 3.0 | + .50 | 50.25 " | 4.45 to 4.55 | + 3.4 | + .57 | 50.28 18.3.26 | 9.45 to 9.55 | + 2.8 | + .47 | 50.23 " | 10.45 to 10.55 | + 2.2 | + .37 | 50.18 " | 11.20 to 11.30 | + 2.9 | + .48 | 50.24 " | 11.55 to 12.5 | + 2.7 | + .45 | 50.22 " | 12.15 to 12.25 | + 2.1 | + .35 | 50.17 18.3.26. | ||