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).
Test report comparing the audibility of Lucas High Frequency and Klaxon motor-driven horns.
| Identifier | ExFiles\Box 59\3\ Scan183 | |
| Date | 7th July 1932 | |
| COPY FOR FILES. X1069 7.7.32. TEST OF LUCAS HIGH FREQUENCY & KLAXON (MOTOR DRIVEN) HORNS. Position of Horns. Lucas on front dumb iron. Klaxon under bonnet. Both were just audible at a distance of 1.6 miles away. Audibility of Lucas improved more than the Klaxon to 1 mile away. Nearer than this there is little to choose between them except that the Lucas note is instantaneous and the Klaxon takes a little time to build up. There was no wind during this test. G.I. | ||