Diagram, section of an improved apparatus for ascertaining the sensitiveness of safety-lamps when used for gas-testing by Frank Clowes A schematic diagram, labelled figure 2, showing 'a large cubical wooden box or chamber, into the upper part of which the requisite measured volume of methane or firedamp can be introduced, the complete admixture of this gas with the air of the chamber being then secured by swinging up and down a broad wooden flap, the area of which is nearly equal to the square section of the chamber.' Subject: Scientific apparatus and instruments A print of this diagram was published in volume 51 of the Proceedings of the Royal Society alongside the paper 'An improved apparatus for ascertaining the sensitiveness of safety-lamps when used for gas-testing'. 1892