Ashworth

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Ashworth-Hepplewhite-Gray Lamps

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The Ashworth-Hepplewhite-Gray lamp, also know as the A-H-G or Gray lamp, is one of the earliest safety lamps designed for firedamp testing.  The basic design of the lamp includes hollow standards running vertically for admitting air from the top or near the base, and feeding the flame in an underdraft fashion.  Through utilizing shutters, the lamp can admit air from only the top of the lamp for testing of thin layers of gas close to the roof.  While just being used as a light source,  the top shutter would be closed while the shutters towards the bottom of the lamp would be opened. This would provide excellent illumination (about .75 candlepower) and safe in sir currents up to 6,000 feet per minute.

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The A-H-G lamp saw many years of service. There were many, many variations made.  Most have 4 standards, but some were made with 3.  Most were made of brass, some were made of aluminum, and some were brass and aluminum. The “Gray-Beard” lamp incorporated a Beard-Mackie indicator with the A-H-G design.

“Gray-Beard” Lamp. Click to enlarge.

Most of these lamps were made England by Davis of Derby, but J. Cooke, Teale, and Akroyd and Best all made them too.  In the US, American Safety Lamp & Supply and Davis of Baltimore made them.  I have not been able to identify any makers on the Continent, though I suspect that there must of been at least one maker.  Gray lamps where used from the 1880’s till the 1920’s.