With the dividers set at five inches we sweep the short arc _m_ from
_B_ as a center. From the intersection of the line _h B h'_ with the
arc _m_ we lay off on said arc and above the line _h'_ four and a half
degrees, and through the point so established draw the line _B j_.
We next set the dividers so they embrace the space on the radial line _A b_
between its intersection with the line _B j_ and the center _A_, and
from _A_ as a center sweep the arc _i_, said arc defining the _addendum_
of the escape-wheel teeth. We draw a line from the intersection of the
radial line _A f_ with the arc _i_ to the intersection of the radial
line _A g_ with the arc _a_, and thus define the impulse face of the
escape-wheel tooth _D_. For defining the locking face of the tooth we
draw a line at an angle of twenty-four degrees to the line _A g_, as
previously described. The back of the tooth is defined with a curve
swept from some point on the addendum circle _i_, such as our judgment
will dictate.
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