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).
Blueprint detailing the specifications for a valve hole on a circular component.
| Identifier | ExFiles\Box 170\1\ img014 | |
| Date | 3rd November 1938 | |
| HOLE FOR VALVE .633" .618" DIA. 14 1/2 LB. SK. 101 A.d.S 3-11-38 | ||