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).
List of standard temperatures for sentinels in degrees Celsius.
| Identifier | ExFiles\Box 45\4\ Scan195 | |
| Date | 3rd September 1923 | |
| X. 4079 3.9.23. STANDARD TEMPERATURES FOR SENTINELS. 65° C 69° C 73° C 77° C 82° C 87° C | ||