Dr M'Kendrick showed an extremely sensitive flame made by Dr R. Koenig. It is constructed on the type of the sensitive flame apparatus devised by Barrett and improved by Govi. A Lecomte burner directs the gas towards a fine wire gauze screen, and when the gas is lit above the screen the flame is very sensitive at ordinary pressures. The special part of the apparatus now shown consisted of a funnel or resonator placed at right angles to the Lecomte gas-jet and opening into the space below the gauze screen. To ensure success a fine stop-cock or clip must be used for the regulation of the quantity of gas. Dr M‘Kendrick showed also that by placing a glass tube 460 mm. in length by 40 mm. in diameter over the flame, and about 4 mm. above the level of the gauze, as first suggested by Geyer, a musical note was heard which was disturbed by vibrations acting on the flame. The apparatus not only showed the ticking of a watch, placed in the resonator, by the movements of the flame, but with each “tic” the tube sounded slightly. The slightest movement in the vicinity of the apparatus agitated the flame; and as the latter was arranged so as to be near the point when it evoked the tone of the tube, now and again the tube gave forth a strong tone as a vibration acted on the mass of gas below the gauze.