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).
Road testing various C.A.V. head lamps and bulbs to determine the best combination for driving light.
| Identifier | ExFiles\Box 61a\1\ scan0021 | |
| Date | 23th November 1914 | |
| From Exp. Dept. Copies for: J.{Mr Johnson W.M.} R.{Sir Henry Royce} Da.{Bernard Day - Chassis Design} Na.{Mr Nadin} X.1354. Wor{Arthur Wormald - General Works Manager}/Hy{Tom Haldenby - Plant Engineer}6/L231114. November 23rd. 1914. X/1357 Re Head Lamps. X.1369 I have tried various combinations of C.A.V. head lamps and bulbs on the road and have come to the conclusion that the one which gives the best driving light is the large model F lamp fitted with a No.13 bulb, which is rated at 48 C.P. On a dark night with wet muddy roads one could see a distance of four telegraph posts ahead, which allows of quite a high speed with comparative safety. The field covered by the lamps is also quite good. It is essential that the lamps should be correctly focussed and properly set on the brackets to get the best results. The medium F type lamps such as we usually recommend do not give nearly such good results even when fitted with the same bulbs. The C.A.V. bulbs are of Ediswan make and the present type of filament is of spiral form running straight forward. The spiral is of small diameter and the source of light is very condensed thus allowing of correct focussing. The No.13 C.A.V. bulb takes 2.6 amperes. It is interesting to note that we have experienced greater reliability with Ediswan lamps recently than with | ||