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).
Specification table detailing the electrical properties of various magnetos.
| Identifier | ExFiles\Box 4\5\ 05-page159 | |
| Date | 24th June 1921 guessed | |
| -3- Contd. (17) (18) (19) (20) (24) Magneto. Contact breaker ringing speed (R.P.M.). Primary resistance (ohms). Secondary resistance (ohms). Secondary m.a. on 108 volts 50~ Remarks. Hor. Vert. Eisemann .68 ohms at 17°C 2668 at 18°C. 14.5 5.9 U.S.A. Bosch DUZ.6 .40 " at 18°C 3200 at 12°C. 11.9 8.1 U.S.A. Bosch ZR.6 .345 " at 19°C 3230 at 18°C. 11.9 7.2 Watford EC6 .53 at 15°C 2800 at 16°C 15.5 10.5 Watford ELC6. .73 at 18°C 3980 at 20°C 9.9 8.2 | ||