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).
Hand-drawn graph plotting Horsepower (HP) against Revolutions Per Minute (RPM) for an 'Average 10 Engine 20HP Unit'.
| Identifier | ExFiles\Box 74\4\ scan0194 | |
| Date | 26th February 1925 guessed | |
| Average 10 Engine 20HP Unit HP 60 50 40 30 20 10 0 R.P.M. 500 1000 1500 2000 2500 3000 [Signature] B/3/W | ||