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).
The results of retesting an A.T. Speedometer and its performance issues.
| Identifier | ExFiles\Box 50\4\ Scan168 | |
| Date | 1st March 1928 | |
| X4308 A246 To Hs {Lord Ernest Hives - Chair} /AJL. from EFC. {E. Fowler Clarke - Electrical Engineer} EFC {E. Fowler Clarke - Electrical Engineer} 4/T1.3.28. A.T. SPEEDOMETER A.246. 745. 15/52. This instrument was tested by us in August last and reported as per copy attached. We have now retested the instrument and find that at a temperature of 18.4ºC. the m.p.h. indicated at the standard speed of 600 r.p.m. are 47.6. You will note that this is in exact agreement with the previous result. It was our intention to have this machine back again after the 10,000 mile test to see if its indications alter due to loss of magnetism. You will note that this instrument is not fitted with the latest alteration to overcome the temperature error and moreover that it is reading low even at ordinary temperatures, because the correct reading at 600 r.p.m. should be 49.25 m.p.h. EFC. {E. Fowler Clarke - Electrical Engineer} | ||