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).
Hand-drawn electrical connection diagram for a dual ignition system.
| Identifier | WestWitteringFiles\N\2October1925-December1925\ Scan121 | |
| Date | 4th November 1925 guessed | |
| CONNECTION DIAGRAM. SW₂ SW₁ HT₁ S₁ P₁ C₁ CB₁ CB₂ P₂ S₂ C₂ HT₂ | ||