Improvements in or relating to Acoustically Operated Electric Contact actuating Mechanism and Systems employing the same

130,376. Heap, A. C., and Field, A. B. Feb. 4, 1918. Sound, controlling and actuating apparatus by; subaqueous audible signals; buoy, life-buoy, raft, and like signals; signalling proximity of land, vessels, icebergs, and the like.- Relates to electric contact devices actu. ated by sound or like waves, and consists mainly in the combination of two sets of apparatus actuated by sound waves of different strengths or character, so that one apparatus when actuated disarms or prevents the action of the other. In the form shown in Fig. 1, an acousticallyactuated contact device A provided with a floating contact 4 as described in Specification 130,375, is connected through resistances, reactances, and condensers to a battery B and to a fuse 9 for firing a mine; and another acoustically actuated contact device C is connected through a relay 16 and a thermal switch 17 to a battery B . If the device C is actuated, for example by an explosion in the neighbourhood, the relay 16 short circuits the fuse 9, thus rendering the device A ineffective; but after a given time the bi-metal coil thermal device 17 breaks the relay circuit at 18, and the fuse 9 is again rendered operative. Other combinations of circuits controlled by two acoustically-operated contact devices are described. For use on a mine, the two contact devices A, C are enclosed in one casing 1, Fig. 5, with junction boxes 67, 81 for the electric connexions. This casing 1 is inserted in a socket 90, Fig. 6, on a mine 92, and is secured by screws to a flange 94 in the socket. A suitable electric battery for use in this connexion comprises a copper band 100, Figs. 9 and 10, secured to the mine 92 but insulated therefrom. the sea water constituting the electrolyte, and the band 100 and mine 92 the electrodes, these being provided with terminals 105, 106 respectively. The copper band is fastened by rivets 101 to a strip of canvas 102, and this is secured to the mine 92 over another strip of canvas 103 by means of other rivets 104. Signals actuated by such devices may be sirens or horns arranged to give Morse code signals. Where a number of such devices are provided on buoys or in mine fields, they may be made to give different signals, which would serve for example to indicate the progress of an enemy submarine vessel through the field. The devices are actuated automatically by the approach of an enemy submarine or under control from a distance. Mines provided with such devices may be supported at a convenient dis