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).
The wear and performance of iridium-platinum versus tungsten ignition points on experimental cars.
| Identifier | ExFiles\Box 35\6\ scan 087 | |
| Date | 4th January 1922 | |
| Mr. Clark. ---------- X2894 4.1.22 X.3656 X.2894.. 25% iridium platinum points fitted to 4 EX appear to be burning. A good surface is maintained. No. of Miles run up to date is 1,415. Tungsten points fitted to 1 EX. Pip formed on screw point after 2,561 miles. Was then reset - another pip has formed after a further 2,778 miles. (Sgd) G.W.H. | ||