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).
Material specification report, number 238B, detailing valve hardness after testing.
| Identifier | ExFiles\Box 150\1\ scan0233 | |
| Date | 22th October 1936 | |
| Rm {William Robotham - Chief Engineer} /Swdl. {Len H. Swindell} 3/JH. -2- 22nd October, 1936. Specification Number 238B. Carbon .4 to .5% Silcon 3.25 to 3.75% Manganese .4 to .6% Sulphur Not more .03% Phosphours Not more than .5% Chromium 7.5 to 8.5% Nickel Not more than .5% The hardness figure of the valves after test varied from 200-400 and we are going to check this over on the remaining 6 valves which have not yet been run. Yours sincerely, | ||