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).
Typed list of dated entries from 1922-1923 with corresponding numerical values.
| Identifier | ExFiles\Box 174\5\ img236 | |
| Date | 18th June 1923 | |
| Dec. 29th 1922 7. March 2nd 1923 18. " 29th " 5. May 31st " 6. June 18th " 6. --- } 16/- | ||