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of thin platinum wire, F, which is carefully soldered on to them. 
Finally, a metal cap, gg, is screwed on to the lower end of the 
cylinder to protect the wires and hold the priming. In the 
cap there is a small loading-hole closed by a screw, h. The 
priming may be either gunpowder, gun-cotton, or — if, as will be 
generally the case, the torpedo is loaded with gun-cotton — deto- 
nating fulminate of mercury. If the latter is used, the cap which 
holds it must be strengthened, in order to ensure detonation at 
the moment of ignition. Of the wires, one will belong to, or 
be connected by an insulated joint with, the conducting cable, 
and the other will be left uninsulated, in order to act as an 
earth-plate, and pass the current into the water and thence to 
the ground. This was the fuze used by the Confederates, and it 
was always found to act well. On account of the strength of 
the current, it can be fired even when there is a fault in the 
insulation of the cable ; and this alone is a great advantage, for 
of all the parts of the apparatus the cable is the one most liable 
to injury. 
High-tension fuzes require a more perfectly insulated cable, 
but smaller battery power. A great number of them have 
been designed, nearly all on the same principle. Baron von 
Elmer’s fuze, used by the Austrians in 1866, is one of the 
simplest. It consists of a small hollow cylinder of gutta- 
percha, A A (fig. 6), about three-fifths of which is filled with an 
insulating material, b, formed of a mixture of sulphur and 
glass ground to powder. A wire is introduced at c, passes 
through the insulator, is bent back at n, passes again through 
the insulating material, and comes out at e. The little arch at 
D is then cut through with a file, so as to leave a very small 
separation between what are now the extremities of the two wires 
CD, ED. The fuze is then primed by filling the vacant space 
around d with a highly inflammable composition, consisting of 
chlorate of potassium and sulphate of antimony, with a little 
powdered plumbago to give it a slight conducting power. This 
priming is at once ignited by the passage of a current through 
it at the little gap between the wires at d. The other ends of 
the wires are of course arranged in the same way as those of 
the platinum-wire fuze. Beardslee’s fuze, invented by Mr. 
Beardslee, of New York, is still simpler, and possesses the great 
advantage that it is always easy to procure the materials of 
which it is composed, and it can therefore be readily extem- 
porised. It is made as follows : — T^ke a small cylinder of 
light soft wood A (fig. 7), and drive two copper nails through 
it, so that their heads will be very near each other but not 
touching, and their points may project below it at some 
distance apart. Then draw a line, with a pencil, across the 
two heads and connecting them. Attach the upper ends of the 
