Diagrams and photographs, experimental equipment and results by Frank Clowes Three photographs, labelled figure 1, showing several views of Clowes' portable safety-lamp; nine ink diagrams, labelled figures 2-10, showing observations and results of Clowes' investigations into exact measurements of flame-cap indications. Subject: Scientific apparatus and instruments Prints of these diagrams and photographs were published in volume 52 of the Proceedings of the Royal Society alongside the paper 'A new portable miner's safety-lamp, with hydrogen attachment for delicate gas-testing; with exact measurements of flame-cap indications furnished by this and other testing lamps'. 1893