=Cut-out, Wedge.= A cut-out operated by a wedge, such as a spring-jack or the plugs at the end of the flexible wires on the switch-boards of telephone exchanges. D =Damper.= A frame of copper on which the wire in a galvanometer is sometimes coiled. It acts to check the needle oscillations. A brass or copper sheathing or tube placed between the primary and secondary coils of an induction-coil to cut off induction and diminish the current and potential of the secondary circuit. When the tube is drawn out gradually the induction increases. It is commonly used in medical coils to adjust their strength of action. =D-C.= An abbreviation for direct current. =Dead Earth.= A fault in telegraph and telephone lines which consists in the ground-wire being improperly grounded, or not fully connected with the earth. =Dead Turns.= A term applied to the ten to twenty per cent. of the convolutions or turns of wire on an armature which are considered to be dead. There are supposed to be about eighty per cent. of the turns on an armature that are active in magnetizing the core; the balance are outside the magnetic field and are termed dead, although they are necessary to the production of electro-motive force. =Dead Wire.= A wire in the electric circuit through which no current is passing. A disused or abandoned electric conductor, such as a telegraph wire, or a wire which may be in circuit, but through which at the time of speaking no electrical action is taking place. =Death, Electrical.= Death resulting from an electric current passing through the animal body--electrocution; accidental death by electric shock; premeditated death through bringing the body in direct contact with conductors carrying high electro-motive force. High electro-motive force is essential, and the alternating current is most fatal. =Decomposition, Electrolytic.= The decomposition or separation of a compound liquid into its constituents by electrolysis. The liquid must be a conductor or electrolyte, and the decomposition is carried on by means of electricity. The conversion of two or more chemicals into a new compound or substance. =Deflection.= In magnetism, the movement of the needle out of the plane. It is due to disturbance, or to the needle’s attraction towards a mass of iron or steel or another magnet. =Demagnetization.= The removal of magnetism from a paramagnetic substance. The process is principally in use for watches which have become magnetized by exposure to the magnetic field surrounding dynamos or motors. =Density, Electric.= The relative quantity of electricity, as a charge, upon a unit area of surface. It may be positive or negative. Surface density, as the charge of a Leyden-jar.