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).
Comparison of two B coils, testing for spark length, high-speed sparking, and insulation.
| Identifier | ExFiles\Box 45\4\ Scan024 | |
| Date | 14th September 1922 | |
| EFC. PB.52. X4079 Sept. 14th. 1922. X.4079" - COMPARISON OF B COILS Of the two B coils we now have, the one recently obtained, by comparison with our experimental coil on spark length, sparking at high speeds and coil quantities, appears to be the better of the two. It has also been run with secondary open circuited to make sure that it is sound as regards insulation. CAP. | ||