that the fibres are all heated equally right through to the centre of
the stick. If this does not receive sufficient attention the bow can
not possibly retain its curve, for the inner fibres that have not
been affected by the heat will always be trying to resume their
original straight position, and are bound ultimately to overcome the
resistance of the heated outer fibres, with the result that the bow
either becomes straight or warped and twisted, most probably the
latter. To understand that this must be so it is only necessary to
remember that any elastic rod, a walking stick for example, can be
held so as to form a curve but as soon as the pressure is released it
immediately recovers its normal state. This is what happens with the
unheated inner fibres in an inferior bow. The constant strife of
opposing forces _must_ result in victory for the active force of the
inner fibres over the passive resistance of the heated outer fibres.

For the operation of "setting" the bow is left about half as thick
again as the finished stick is intended to be: this to allow for
scorching or burning the outer surface. When the "setting" is
satisfactorily accomplished the stick is planed up round, after which
the bottom trench is cut. This is the slot in which the screw-eye of
the nut travels. Then the hole for the screw itself is drilled out in
a lathe fitted with a "Cushman chuck." The next thing is to put on
the "black face." This is a thin slab of ebony glued on to the under
surface of the head, which helps to strengthen the head and forms a
solid bed for the ivory or metal plate which forms the outer facing
of the head. The ivory faces are cut out of the solid tusk to the
shape shown in Fig. 36. They are glued on with the very best glue
procurable and tied down with strong twine. This is another matter of
extreme difficulty and delicacy, as ivory is a very stubborn material
to work in and it is easy to crack it in forcing it down to the curve
of the face, that is if it is sufficiently thick adequately to fulfil
its original purpose as a strengthener and protector of the head. One
often sees in cheap bows faces of ivory so thin as to show the ebony
face through in a bluish tint. Such a face is of as much value to the
bow as a piece of paper, but it was easy to put on!

[Illustration: FIG. 36.]

Metal faces are growing more and more into favour but, personally, I
prefer a substantial ivory face, for though the metal may be strong