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).
The creation of a reference sheet for the properties and faults of resistance wires made from various alloys.
| Identifier | WestWitteringFiles\D\May1920\ Scan6 | |
| Date | 17th May 1920 | |
| To EFC. from R.{Sir Henry Royce} Copy to CJ. ORIGINAL RECEIVED X.1623 RE RESISTANCE WIRES OF VARIOUS MATERIALS To enable us to judge the value of received alloys, I suggest you make a large reference sheet shewing - (1) The specific resistance in ohms per one-thousandth of a square inch area (not circular) per inch of length (single unit system) (2) X time copper (for which we have various tables) (3) Current carrying capacity at redness. (4) and when it droops, relative stiffness at a red heat or judging by extra temperature it will bear without drooping. These wires have three faults which should be watched for. The first is a tendency to disintegrate if repeatedly heated or maintained at a high temperature, and exposed to air. The third rusting. (5) Also give the temperature coefficient, it is needed occasionally to be high, but mostly nil or negative. (6) A note might be added of the special virtue or use of each alloy. For instance, one thinks manganim excellent for silk covered resistance coils, but not high temperature imperfectly supported resistance coils. R.{Sir Henry Royce} | ||