LOCATING THE OUTER ANGLE OF THE IMPULSE PLANES.
The intersection of this line with the addendum arc _l_ locates the
outer angle of the impulse planes of the teeth, and we name it the point
_x_. From the point _r_ we lay off on the arc _a_ seven degrees and
establish the point _v_, which defines the extent of the angular motion
of the escape wheel utilized by pallet. Through the point _v_, from _B_
as a center, we sweep the short arc _m_. It will be evident on a
moment's reflection that this arc _m_ must represent the path of
movement of the outer angle of the exit pallet, and if we measure down
ten degrees from the intersection of the arc _l_ with the arc _m_, the
point so established (which we name the point _s_) must be the exact
position of the outer angle of the pallet during locking. We have a
measure of ten degrees on the arc _m_, between the lines _B g_ and _B
h_, and by taking this space in the dividers and setting one leg at the
intersection of the arc _l_ with the arc _m_, and measuring down on _m_,
we establish the point _s_.
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