FUZE  or FusE, an appliance for firing

explosives in blasting operations, military shells, &c . (see BLASTING and AMMUNITION, § Shell) . The spelling is not governed by authority, but modern convenience has dictated the adoption of the " z " by military engineers as a general rule, in order to distinguish this sense from that of melting by heat (see below) . The word, according to the New English Dictionary, is one of the forms in which the Lat. fusus, spindle, has been adapted through Romanic into English, the ordinary fuze taking the shape of a spindle-like tube . Similarly the term "fusee" (Fr. fusee, spindle full of tow, Late Lat. fusata) is applied to a coned spindle sometimes used in the wheel train of watches and spring clocks to equalize the action of the mainspring (see WATCH); and the application of the same term to a special kind of match may also be due to its resemblance to a spindle . Again, in heraldry, another form, " fusil," derived through the French from a Late Lat. diminutive (fusillus or fusellus) of this same fuses, is used of a bearing, an elongated lozenge . According to other etymological authorities, however (see Skeat, Etym . Dict., 1898), " fuze " or " fuse," and " fusee " in the sense of match, are all forms derived through the Fr. fusil, from Late Lat. focile, steel for striking fire from a flint, from Lat. focus, hearth . The Fr. fusil and English " fusil " were thus transferred to the " firelock," i.e. the light musket of the 17th century (see FUSILIER) . In electrical engineering a " fuse " (always so spelled) is a safety device, commonly consisting of a strip or wire of easily fusible metal, which melts and thus interrupts the circuit of which it forms part, whenever that circuit, through some accident or derangement, is caused to carry a current larger than that for Which it is intended . In this sense the word must be connected with fusus, the past participle of Lat. fundere, to pour, whence comes the verb " fuse," to melt by heat, often used figuratively in the sense of blend, mix .