Laboratory report with two microphotographs comparing the surfaces of Woodhead's and Firth's springs.
| Identifier | ExFiles\Box 154a\4\ scan0064 | |
| Date | 7th December 1937 guessed | |
| ROLLS-ROYCE LABORATORY REPORT: M.1486/6 x 250 Upper surface of Woodhead's spring after removing .002" depth of material. M.1486/7 x 250 Upper surface of Firth's spring No.1. after removing .002" depth of material. | ||
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).