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 testing of HF.728 and WT.13/WT.23 Mellotone horns.
| Identifier | ExFiles\Box 167\1\ img303 | |
| Date | 19th December 1938 guessed | |
| -6- HORNS. A sample of HF.{H. W. Frost - Coachwork Inspector}728 Horns were left for us to test, these having been reduced to 100 phons, the maximum permissible for this type of horn. However, since the alteration to the date on which this revision must take place, our interest in this item has diminished, and it is unlikely that we shall do anything further, beyond giving them a brief noise test. We have received a pair of WT.13 Mellotone Horns, limited to 105 phons, the maximum permissible for this horn, illustrating what our future production will be, and also a pair of WT.23 Mellotone Horns with a cheaper interior which represents a saving of 1s. 0d. per horn, and these will be put on test. BY/ [Signature] | ||