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).
Page of test results with diagrams, detailing spark performance under various conditions.
| Identifier | ExFiles\Box 63\4\ scan0013 | |
| Date | 26th May 1918 guessed | |
| (13) (55) ZA2/600/5/R/A Same as for advance. (56) ZA2/600/5/R/B Ditto (57) ZA2/600/7/A/A Single spark & less arc than for 5mm. gap. (58) ZA2/600/7/A/B No spark. (59) ZA2/600/7/R/A Same as for advance. (60) ZA2/600/7/R/B No spark. | ||