Many modifications of it have been from time to time devised by Mr. Abel; a section and elevation of the more recent form of his fuze is shown at Fig. 29. It consists of _b_, _b_, a body of beech wood, hollowed for half its length, in which space the priming charge is placed; it is also perforated by three holes, one vertical for the reception of the capsule of sensitive mixture, the other two horizontal, in which the conducting wires are placed; _a_, _a_ are two insulated copper wires, passing into the vertical hole, and resting on the sensitive mixture; in a cavity, _d_, of the body of the fuze is placed some mealed powder, which is fired by the ignition of the sensitive mixture on the passage of the electrical current. The insulated wires used in connection with this fuze consist of two copper wires, about 2 inches long, and ·022 inch in diameter, enclosed in a covering of gutta percha ·13 inch in diameter, and separated about ·06 inch from each other. At one end the wires are bared to 1·25 inch, at the other they are merely cut across by a very sharp pair of scissors. This end of the double covered wire is inserted into a paper cylinder _c_, _c_, which holds a small quantity of the priming mixture. This capped end of the wires is inserted into the wooden body of the fuze through the vertical hole _i_, and projects ·15 inch into the cavity _d_. The bare ends of the double covered wires are pressed into small grooves in the head of the cylinder _e e_, and each extremity is bent into one of the small channels _d' d'_, which are at right angles to the vertical perforation. _d' d'_ are two small copper tubes driven into these channels over the wire ends, to keep the wires in position, and to form the opening into which the conducting wires _f_ are inserted and bent round, as at _e'_. The priming mixture of Abel's original fuze, which was the one used by the Confederates, was composed of 10 parts of subphosphide of copper, 45 parts of subsulphide of copper, and 15 parts of chlorate of potash. These ingredients reduced to a very fine state of division, and intimately mixed, in a mortar, with the addition of a little alcohol, are dried at a low temperature and preserved in bottles until required for use. The sensitive mixture used by Mr. Abel more recently for his submarine electrical high tension fuzes, is composed of an intimate mixture of graphite and fulminate of mercury. By the process of ramming, the electrical resistance of the fuze is regulated. _Extempore Fuzes._--It may be necessary in some cases, when a specially manufactured fuze is not attainable, to make a fuze on the spot. The following is a neat and simple method of constructing an extempore high tension fuze.