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 table for calculating the placement of divisions on a contracted scale from an original proportional scale.
| Identifier | ExFiles\Box 59\2\ Scan126 | |
| Date | 23th March 1931 guessed | |
| -6- d₀ Original reading in miles per hour on proportional scale. .00036 d₀² d divisional position on the old proportional scale at which the division corresponding to d₀ miles per hour on the new contracted scale should be placed. 0 0 0 10 .036 9.964 20 .144 19.856 30 .324 29.676 40 .576 39.424 45 .73 44.27 50 .90 49.10 60 1.30 58.70 70 1.76 68.24 80 2.30 77.70 90 2.92 87.08 | ||