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).
Comparison table of test results for various magnetos, including Watford, Bosch, Dixie, Conner, and B.T.H.
| Identifier | ExFiles\Box 48\3\ Scan098 | |
| Date | 1st January 1919 | |
| -3- A. {Mr Adams} Contd. Magneto. | (17) Contact breaker firing speed (R.P.M.) | (18) Primary resistance (Ohms). | (19) Secondary resistance (Ohms). | (20) Secondary m.a. on 108 volts 50~ Hor. Vert. | (24) Remarks. Watford. | | .54 at 19°C. | 3319 at 19°C. | - | - | - " | | .535 at 18°C | 3057 at 18°C. | 15.5 | 9.4 | - " | | .51 at 14°C. | 2600 at 15°C. | 20.3 | 9.6 | - " | | .49 at 16°C. | 2840 at 17°C. | 20.1 | 11.2 | - R.Bosch. | | .73 at 15°C. | 2849 at 16°C. | 9.4 | 5.3 | - U.S.A. Bosch. | | .935 at 20°E. {Mr Elliott - Chief Engineer} | 3106 at 21°C. | -8.4 | 6.7- | Low speed sparking characteristics taken before endurance test on which test magneto broke down on H.T. brush. U.S.A.Bosch. | | -- | -- | - | - | - Dixie. | | .68 at 16°C. | 3458 at 16°C. | 12.8 | 8.4 | - Conner. | | .51 at 18°C. | 2400 at 19°C. | 13.6 | 8.1 | - B.T.H. | | .76 at 14°C | 2690 at 16°C. | 22.4 | 16.3 | Gap had to be increased to obtain slow speed figures owing to distortion produced on endurance test. Handwritten text in column (17): Not observed Footer text: R.R. 43 150 1-19 S.&Co. 648-19-F6-499 | ||