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 use of coloured cottons to distinguish coil tappings.
| Identifier | ExFiles\Box 69\1\ scan0320 | |
| Date | 21th March 1930 | |
| X8710 To EFC. 21.3.30. EFC2/ADL1.2.30. Herewith coils as per your To distinguish the tappings I have used coloured cottons. Layer 2. 1 white cotton. " 4. 2 " " 6 3 " " 10 1 red " " 14 2 " " 18 3 " " 26 1 blue " " 34 2 " " 42 3 " " 50 4 " " 60 10/40 Flex. E.J.Brock. | ||