Improvements in or relating to Electric Lamps

19,431. Adams, F. G. W. J. Aug. 23. Miners' and like safety lamps, electric. The bulb A of an electric incandescent lamp is surrounded by an outer bulb C, enclosing air or other fluid at a higher or lower pressure than that of the atmosphere, by which a cut-out is held normally closed, so that, i the outer bulb C is broken, the lamp is disconnected. In the form shown, the lamp A is supported in the outer bulb C by a bulb B which is divided by two flexible diaphragms D, the space between these communicating with the space in the outer bulb C ; when this space is exhausted, a wire H , supported by the diaphragms, makes contact with the adjacent leading-in wire. In another form, the diaphragms D are replaced by a curved metal tube, closed at its free end and communicating at the other end with the space in the outer bulb C, so that when this is exhausted the tube bends further and makes a connection. In another form, the outer bulb C contains a glass tube, open at one end, and having two wires sealed into it. These are normally connected by a little mercury in the tube, but, if the outer bulb C is broken, the mercury moves and breaks contact.