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).
Graph plotting leakage resistance versus temperature for a new KLG 850 A spark plug, showing performance during heating and cooling cycles.
| Identifier | ExFiles\Box 150\1\ scan0192 | |
| Date | 29th August 1936 | |
| NEW PLUG (KLG 850 A) LEAKAGE (MEGOHMS) 2000 1800 1600 1400 1200 1000 800 600 400 200 0 HEATING COOLING TEMP RE °C. 100 200 300 400 500 600 700 800 29.8.36/ | ||