Discussion on “self-contained portable electric mine lamps” (Swoboda), Pittsburgh, Pa., April 9, 1914. (see proceedings for April, 1914)

H. H. Clark: The first requirements of portable electric lamps are safety, and the capacity for uninterrupted production of a sufficient amount of light. I wish to emphasize, however, that from the viewpoint of the mine operator, a lamp to be successful must be able to operate day after day with a reasonable amount of repairs and replacement. If this is to be accomplished the lamp battery must be a very sturdy affair. Failure of the battery plates will result in annoying delays and expensive repairs. A dependable battery is indispensable to satisfactory performance.