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).
Descriptive leaflet for the Stelmar Patent Fog Lamp.
| Identifier | ExFiles\Box 61a\2\ scan0422 | |
| Date | 7th December 1934 guessed | |
| THE STELMAR PATENT FOG LAMP All motorists will remember the inconveniences and dangers experienced during the winter 1933-34 whilst driving through the frequent fogs even with a fog lamp placed low down on the near side of the car for kerb illumination. All drivers appreciate that ordinary head lamps are useless in a fog and actually diminish forward vision. This is due to the short scattered and unfocused rays emitted from the head lamp reflectors, which beat back into the line of vision and blank out objects in front of the car. This precludes entirely the use of ordinary head lamps in fog, and the small fog lamp with yellow glass situated low down on the chassis to illuminate the kerb can obviously throw no appreciable light in a forward direction. The perfect fog lamp must possess the following characteristics :— (a) Elimination of ALL light rays above the horizontal line of the lamp. (b) Intensive light penetration in front of the car. (c) Intensive local illumination of the kerb or the near side. The new Stelmar patent fog lamp which is now on the market is revolutionary in optical design and possesses the following distinctive features, embodying these characteristics in a single unit :— (1) The lamp projects a focused beam (similar to that of a searchlight) with intensive forward penetrating power. The beam is sharply cut off on its upper horizontal boundary, where the light intensity is at its maximum. The lamp is so constructed and the beam so focused that all rays above the horizontal line are entirely eliminated. This intensive light is projected for a considerable and safe distance in front of the car without any back glare or reflection, which is the all important point to the driver. (2) In addition to the projected beam, the lamp has an auxiliary attachment which reflects a diffused beam to the near side kerb. Both sections of this combined beam are derived from a single optical unit of high illuminating power. The Stelmar patent lamp has been developed to meet the requirements of motorists. It is eminently suitable as a head light for motor boats, landing light for aeroplanes in fog, and generally for all those requirements which demand the greatest possible surface illumination without obscuring or otherwise affecting the vision of drivers or pilots. The lamp as constructed can be easily fitted to motor cars, and heavy delivery vans, motor buses and charabancs. THE STELMAR FOG LAMP AND ALL PARTICULARS CAN BE OBTAINED From BANTING & TRESILIAN, LTD., ENGINEERS, 64, VICTORIA STREET, WESTMINSTER, LONDON, S.W.1. | ||