in diameter, bent to the form shown at Fig. 67.
The ends _b b_ of the copper wire are flattened a little and recessed on
their inner faces, as shown in Fig. 70, to grasp the edges of the roller
_A_. The heat of an alcohol lamp is applied to the loop of the wire at
_g_ until the small bit of shellac placed in the hole _h_ melts. The
necessary small pieces of shellac are made by warming a bit of the gum
to near the melting point and then drawing the softened gum into a
filament the size of horse hair. A bit of this broken off and placed in
the hole _h_ supplies the cement necessary to fasten the jewel pin.
Figs. 68 and 69 will, no doubt, assist in a clear understanding of the
matter.

HOW TO MAKE AN ANGLE-MEASURING DEVICE.

We will now resume the consideration of the device for measuring the
extent of the angular motion of the fork and pallets. Now, before we
take this matter up in detail we wish to say, or rather repeat what we
have said before, which is to the effect that ten degrees of fork and
lever action is not imperative, as we can get just as sound an action
and precisely as good results with nine and a half or even nine degrees
as with ten, if other acting parts are in unison with such an arc of
angular motion. The chief use of such an angle-measuring device is to
aid in comparing the relative action of the several parts with a known
standard.

[Illustration: Fig. 71]

For use with full-plate movements about the best plan is a spring clip
or clasp to embrace the pallet staff below the pallets. We show at Fig.
71 such a device. To make it, take a rather large size of sewing
needle--the kind known as a milliner's needle is about the best. The
diameter of the needle should be about No. 2, so that at _b_ we can
drill and put in a small screw. It is important that the whole affair
should be very light. The length of the needle should be about 1-5/8",
in order that from the notch _a_ to the end of the needle _A'_ should be
11/2". The needle should be annealed and flattened a little, to give a
pretty good grasp to the notch _a_ on the pallet staff.

Good judgment is important in making this clamp, as it is nearly
impossible to give exact measurements. About 1/40" in width when seen in
the direction of the arrow _j_ will be found to be about the right
width. The spring _B_ can be made of a bit of mainspring, annealed and
filed down to agree in width with the part _A_. In connection with the
device shown at Fig. 7