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).
Results of a lamp failure test under specific vibration and voltage conditions.
| Identifier | WestWitteringFiles\F\January1921\ Scan39 | |
| Date | 25th January 1912 | |
| 21 EFC1/T25.1.12. -2- Contd. The conditions of the test were as follows :- Volts 13.0 to 14.0 Vibrations = 100 per minute. Drop 1/16" on to rubber pad. The results of this test were as follows :- Failure No. | Lamp Failing. | No. of hrs. run. | Nature of failure. ---|---|---|--- 1 | Head Osram. | 1 | Lamp worked loose in cap. 2 | Mazda head. | 8.5 | Failure of holder which led to lamp falling out. 3 | Osram head. | 16.5 | Lamp worked loose in cap. 4 | Mazda head. | 20 | Solder melted away from lamp cap breaking connection, due to faulty holder causing heat development. 5 | R.E. Head. | 29 | Ditto. 6 | R.E. Head. | 60.5 | Filament burnt out. 7 | Osram side. | 64.5 | Lamp worked loose in cap. 8 | Osram side | 94.5 | Lamp filament fell away. 9 | R.E. Side. | 96.0 | Filament burnt out. 10 | Mazda side. | 99.5 | Filament burnt out. 11 | Mazda side, | 104.0 | Failure of holder which led to lamp falling out. 12 | R.E. Side. | 112.0 | Failure burnt out. | ||