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).
Note about tests being made on the standard worm gear with two variations.
| Identifier | ExFiles\Box 113\1\ scan0019 | |
| Date | 28th June 1924 guessed | |
| [Crossed out text] Tests on being made on the standard worm gear. with, ① considerable positive slack, ② with altered pitch | ||