keep the same number of turns, an equal number of turns may be had
with a corresponding reduction of winding space where enameled wire is
used in place of silk or cotton.

In the matter of heat-resisting properties the enameled wire possesses
a great advantage over silk and cotton. Cotton or silk insulation will
char at about 260° Fahrenheit, while good enameled wire will stand
400° to 500° Fahrenheit without deterioration of the insulation. It is
in the matter of liability to injury in rough or careless handling, or
in winding coils having irregular shapes, that enamel wire is
decidedly inferior to silk or cotton-covered wire. It is likely to be
damaged if it is allowed to strike against the sharp corners of the
magnet spool during winding, or run over the edge of a hard surface
while it is being fed on to the spool. Coils having other than round
cores, or having sharp corners on their spool heads, should not
ordinarily be wound with enamel wire.

The dielectric strength of enamel insulation is much greater than that
of either silk or cotton insulation of equal thickness. This is a
distinct advantage and frequently a combination of the two kinds of
insulation results in a superior wire. If wire insulated with enamel
is given a single wrapping of silk or of cotton, the insulating and
dielectric properties of the enamel is secured, while the presence of
the silk and cotton affords not only an additional safeguard against
bare spots in the enamel but also a certain degree of mechanical
protection to the enamel.

Winding Methods. In winding a coil, the spool, after being properly
prepared, is placed upon a spindle which may be made to revolve rapidly.
Ordinarily the wire is guided on by hand; sometimes, however, machinery