FUSE, or FUZE (ante), for firing shells, torpedoes, blasts, etc. A time F. is regulated to burn for a given time and then communicate fire to the exploding charge. Another time P. is known as the Borneman, and is regulated to a quarter of a second. A per cussion F. is ready for action on discharge:and takes effect after striking any solid object. Care is necessary in making them so that they may not be likely to explode in handling or in ordinary transportation. The form used in the U.S. navy consists of a metal fuse stock inelosing a Movable core-piece or.plunger of steel bearing a musket-cap. When the shell strikes.. the loose-fitting plunger continuing its motion explodes the cap and fires the charge. There are three or four kinds of percussion fuses. The concus sion F. is put in'action by the discharge, but the action is restrained until striking the object. Such fuses are made of high explosive fulminates, and are very danerous to handle. For•mining, electric fuses are used, called also exploders. They are of
two classes: those in which the beat is obtained by the passage of the electric spark over a break in the circuit.; and those in which the heat is 'obtained by the passage of the current. over a conductor of great resistance. The first are tension fuses, and may be used with any static electric machine. There should he a very small break in the circuit, not greater than the spark can be made easily to pass over, and between the points of th6 break should be some substance that will he ignited by the passage of the spark. The second class embrace those in which, by the passage of the current, a portion of the circuit having it great resistance becomes sufficiently heated to ignite some explosive or inflammable substance in contact with it. Such fuses are used with the voltaic bat tery and the various dynamo-electric•machines.