enable the workman to follow our instructions much more readily.


MAKING THE BRIDGES.

In case the reader makes the bridges _C_ and _F_, as shown in Fig. 27,
he should locate small circles on them to indicate the position of the
screws for securing these bridges to the pillars which support them, and
also other small circles to indicate the position of the pivot holes _d b_
for the escape wheel and pallet staff. In practice it will be well to
draw the line _a a_ through the center of the main plate _A_, as
previously directed, and also establish the point _d_ as therein
directed.

The pivot hole _d'_ for the escape wheel, and also the holes at _e e_
and _b_, are now drilled in the bridge _F_. These holes should be about
1/16" in diameter. The same sized hole is also drilled in the main plate
_A_ at _d_. We now place a nicely-fitting steel pin in the hole _d'_ in
the bridge _F_ and let it extend into the hole _d_ in the main plate. We
clamp the bridge _F_ to _A_ so the hole _b_ comes central on the line
_a_, and using the holes _e e_ in _F_ as guides, drill or mark the
corresponding holes _e' e'_ and _b_ in the main plate for the pillars
_E E'_ and the pallet staff.

[Illustration: Fig. 27]

This plan will insure the escape wheel and pallet staff being perfectly
upright. The same course pursued with the plate _C_ will insure the
balance being upright. The pillars which support the bridges are shaped
as shown at Fig. 28, which shows a side view of one of the pillars which