tional strength. Heat
to a very pale red for about one-half inch from the end, and then spread
the point, as shown at _B_, Fig. 24, by a slight blow of the hammer. We
are now ready to temper our drill, and we must exercise a little care
that the steel is not burnt and that the drill is not bent or warped when
hardening. The flame of the alcohol lamp should be reduced as small as
possible, or otherwise the steel may become overheated and lose all its
good qualities. If needles are used for making drills there is a great
liability of their warping when hardening, but when a larger piece of
wire is used there is not much danger, if care is exercised in
introducing the drill that it goes into the compound straight and point
foremost. If a needle is used, it is well to construct a shield for it,
to be used when heating and hardening. This shield can be made from a
small piece of metal tubing, broached out to fit loosely over the shank
and point of the drill. The drill is introduced into this shield as shown
in Fig. 25, and a little soap may be introduced into the end _a_ before
plunging. Various hardening devices are used, but in my experience
beeswax or sealing wax will be found as good as any. Heat the drill (or
if a needle, the drill and shield both), to a pale red and plunge
straight into the wax. In the latter case, where the shield is used, the
shield, on striking the wax, will run up the shank of the drill, allowing
the point to pierce the wax. Some watchmakers introduce the extreme point
of the drill into mercury first and then plunge into the wax. This
hardens the extreme point of the drill very hard, so hard, in fact, that
it will penetrate the hardest steel, but care must be exercised with such
a drill because the mercury makes it not only very hard but very brittle.
_C_, Fig. 24, shows a drill after it has been finished on the Arkansas
stone. This shape of drill will withstand the pressure necessary to drill
into hard steel. Many watchmakers reduce the temper of every staff before
drilling. This, I think, is quite unnecessary. There are very few cases
in which it is necessary to reduce the temper of the staff, and even then
it should only be reduced as far as it is to be drilled, and then not in
excess of a good spring temper.

[Illustration: _Fig. 24._]

[Illustration: _Fig. 25._]

The centering of a staff in wax has been thoroughly described and in
pivoting the proceeding is the same as in staffing. After acc