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).
Telegram confirmation regarding the failure of mica spark plugs compared to porcelain ones.
| Identifier | ExFiles\Box 33\3\ Scan032 | |
| Date | 4th November 1919 | |
| X.1812. b. CONFIRMATION OF TELEGRAM. X 3413 4th November, 1919. ROYCAR DERBY. BARRINGTON HIVES OUR EXPERIENCE INDICATES THAT MICA PLUGS ARE A FAILURE THROUGH LIABILITY TO SOOT UP AND NOT BURN THEMSELVES CLEAN AS PORCELAIN ONES DO UNDER EXACTLY SIMILAR CONDITION. ROYCE. | ||