141. Wire drawing. The metal to be converted into wire is
made of a cylindrical form, and drawn forcibly through circular
holes in plates of steel: at each passage it becomes smaller.
and, when finished, its section at any point is a precise copy of
the last hole through which it passed. Upon the larger kinds of
wire, fine lines may sometimes be traced, running longitudinally.
these arise from slight imperfections in the holes of the
draw-plates. For many purposes of the arts, wire, the section of
which is square or half round, is required: the same method of
making it is pursued, except that the holes through which it is
drawn are in such cases themselves square, or half-round, or of
whatever other form the wire is required to be. A species of wire
is made, the section of which resembles a star with from six to
twelve rays; this is called pinion wire, and is used by the
clockmakers. They file away all the rays from a short piece,
except from about half an inch near one end: this becomes a
pinion for a clock; and the leaves or teeth are already burnished
and finished, from having passed through the draw-plate.
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