Safety lamp, Davy, maker: J. Mills, Newcastle-on-Tyne, marking: makers name, 1828-65

This resembles Inv. No. 1895-101 in construction, and was for a long time the standard form of Davy lamp, but is no longer used in this simple form, as it ceases to afford protection in an explosive mixture when its velocity reaches 400 ft. per min.; also its illuminating power - 0.07 to 0.22 candlepower - is too low for modern needs, A screw lock is fitted.