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).
Table of compression and permanent set measurements for a split type piston under varying weights.
| Identifier | ExFiles\Box 77\3\ scan0044 | |
| Date | 22th November 1919 guessed | |
| SPLIT TYPE PISTON. X3/82 WEIGHT IN LBS | COMPRESSION. | PERMANENT SET 26 | .00425 | nil 36 | .0055 | — 46 | .007 | — 56 | .009 | — 66 | .011 | .001 76 | .0115 | .001 86 | .013 | .001 96 | .014 | .001 106 | .015 | .001 116 | .016 | .001 126 | .017 | .001 136 | .018 | .001 146 | .019 | .0015 156 | .020 | .002 166 | .021 | .002 176 | .022 | .0025 186 | .024 | .0025 196 | .025 | .003 206 | .024 | .00325 | ||