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).
Test results on an instrument's speed reading accuracy at various temperatures.
| Identifier | ExFiles\Box 50\4\ Scan305 | |
| Date | 9th July 1929 guessed | |
| -2- The results of tests on the instrument however, show the speed reading to be considerably higher than this 44.5 miles per hour, namely 47.8 at 30°C, the actual speeds observed being in accordance with the following table - Temperature °C. M.P.H. at 600 R.P.M. Corresponding drive revs. per mile for correct reading. 20.0 48.8 738 23.0 48.3 745 26.0 47.9 752 28.0 47.8 754 30.0 47.8 754 35.0 47.6 756 775 It is therefore suggested that this instrument is reading miles per hour rather higher than is actually desired. We are obtaining a further instrument for a similar test as an indication as to whether these high readings are universal. It should be stated that in regard to the temperature variation between 35° and 20°C this only amounts to 2½% and is considered satisfactory. EFC. {E. Fowler Clarke - Electrical Engineer} | ||