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).
Photographic comparison of two identical bumper springs after different test durations.
| Identifier | ExFiles\Box 95\2\ scan0037 | |
| Date | 6th June 1936 | |
| Top spring: BUMPER No.2. SPRING C.83498. 14 HOURS 25 MINS. SALTFRE. 7.2.36. Bottom spring: BUMPER No.2. SPRING C.83498. 40 HOURS 50 MINS. SALTFRE. 6.6.36. | ||