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).
Diagram from a Mechanics Instruction Book for a Silent-Second Transmission.
| Identifier | ExFiles\Box 137\5\ scan0093 | |
| Date | 1st September 1929 | |
| MECHANICS INSTRUCTION BOOK CB7 SILENT-SECOND TRANSMISSION Held endwise G D A B C E K F I H Printed in U. S. A.{Mr Adams} September, 1929 | ||