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December, 1934
The New Schedule A Lamps
Under the First Schedule of the Coal Mines General Regulations (Lighting) 1934, a minimum standard of lighting for new safety lamps is laid down. Briefly, the new Regulations provide that any new lamp introduced shall give a light at the end of nine hours continuous burning of not less than 0.4 spherical candle power for cap lamps and 0.75 spherical candle power for all other types the mean candle power over the horizontal angle of distribution shall not be less than 1.5. Provision is also made that the light shall be sufficiently and suitably distributed without giving rise to glare, and as far as practicable, without marked contrasts of light and shade. Standard conditions of tests are also to be specified. We give herewith short descriptions of those lamps which appear on the first list of types approved as meeting Schedule A for use in any part of the pit
Alkaline Miners Lamps Limited
PEARSON "NIFE" No. 20. — This lamp incorporates the Nife nickel cadmium alkaline battery and is designed on what is now virtually the standard two-part principle. The main body of the lamp is an accurately machined drop forging and is provided with a square thread for attachment to the bottom part, and a smaller thread to take the screwed ring holding the contact and bulb assembly in position. The contact assembly consists of a solid ebonite moulding carrying a spring loaded contact disc underneath and a die cast bulbholder and an enamelled conical reflector above. The positive plates of the battery consist of nickel hydroxide enclosed in perforated, flattened steel tubes which are interlocked together in a steel frame. The negative plates are similarly constructed so far as the mechanical details go but are filled with the cadmium active material. These plates are grouped together to make two cell halves, adjacent plates being insulated from each other by ebonite rod separators. Each group of plates is engirdled with a close fitting and appropriately shaped steel sleeve. Solid steel terminals are provided and are foolproof as regards hanging in the charging rack is concerned since the positive and negative terminals are of different diameters. Gas release valves having a rubber sleeve release are fitted and electrolyte level indicators, the latter being of the electric circuit pattern.
PEARSON "NIFE" CAP LAMP, No. 12. — A view of the cap lamp supplied by this firm is illustrated herewith. The alkaline battery has a capacity of about 12 ampere hours and is enclosed in a welded steel case. The bakelite headpiece carries a 25 volt 1 amp. bulb and the weight of the complete lamp is 7 lb.
Drawings and Photographs accompanying the article
Article reproduced from a copy of the magazine held at National Mining Museum Scotland, Newtongrange, Midlothian.
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