There are numerous advantages accruing from the use of platinum wire fuzes, the chief of which are here enumerated:-- _a._--Great facilities for, and entire safety whilst testing the circuit. _b._--Extreme simplicity of manufacture. _c._--Non-liability to deteriorate. _d._--Perfect insulation of the electric cables used in connection with submarine mines not necessary. _English Service Platinum Wire Fuze._--The following is a description of the platinum wire fuze of the form adopted in the English service, a section of which is shown at Fig. 24. It consists of a head of ebonite _a_, hollowed out, in which a metal mould is fixed, the wires which have been previously bared are inserted into holes in this mould, and firmly fixed thereto by means of a composition poured into the mould, whilst hot; this is shown at _b_. The two bared ends of the wires which project beyond the metal mould, as _c_, _c_, are connected by a bridge of platinum-silver wire ·0014" in diameter and weighing ·21 grs. per yard. This is effected as follows:-- A very fine shallow groove is made in the flat ends of the bare wires _c_, _c_, and the platinum-silver wire is laid across in the incisions, and fixed there by means of solder. The length of the bridge _d_ is ·25." A tube _e_, made of tin, and soldered to a brass socket _f_, is fixed by means of cement to the ebonite head _a_; in this tube is placed the fulminate of mercury, the open end of the tube _g_ being closed with a pellet of red lead and shellac varnish; around the bridge of the fuze is placed some loose gun-cotton. _McEvoy's Platinum Wire Fuze._--Another form of platinum wire fuze, which has been devised by Captain McEvoy, formerly of the Confederate Service, is shown at Fig. 25. It consists of the head _a_, formed of a mixture of ground glass, or Portland cement, worked up with sulphur as a base: this mixture when hot is poured into a mould, in which the two insulated copper wires, _b_, _b_, have been previously placed; when cold, the mixture with the wires affixed is removed from the mould, and the platinum wire bridge _c_ being secured to the bare ends of the copper wires, the whole is firmly fixed in a brass socket _d_, by means of cement; the space _e_ is filled with loose dry gun-cotton, so as to surround the bridge _c_; a copper tube _f_, closed at one end, is partly filled with fulminate of mercury, and when the fuze is required for service, this tube is secured to the brass socket _d_ by means of cement. In this form of low tension fuze there is no liability whatever of any injury being caused to the bridge by the working of the wires in the head, or by damp even after lying in the water for a month or more. One peculiarity of this fuze is that the composition is run over the insulated wires without materially softening the dielectric, or affecting in the slightest degree the insulation of the wires.