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"Watch and Clock Escapements A Complete Study in Theory and Practice of the Lever, Cylinder and Chronometer Escapements, Together with a Brief Account of the Origin and Evolution of the Escapement in Horology"



[Illustration: Fig. 18]
The point on the arc _n_ where it intersects with the line _b'_ is
termed the point _b_. At the intersection of the radial line _a d'_ is
established the point _d_. We take ten and one-half degrees in the
dividers, and from the point _b_ establish the point _c_, which embraces
the arc of the escape wheel which is utilized by the pallet action.
Through the point _b_ the line _h' h_ is drawn at right angles to the
line _a b'_. The line _j j'_ is also drawn at right angles to the line
_a d'_ through the point _d_. We now have an intersection of the lines
just drawn in common with the line _a a'_ at the point _g_, said point
indicating the center of the pallet action.
The dividers are now set to embrace the space between the points _b_ and
_g_ on the line _h' h_, and the arc _f f_ is swept; which, in proof of
the accuracy of the work, intersects the arc _n_ at the point _d_. This
arc coincides with the locking faces of both pallets. To lay out the
entrance pallet, the dividers are set to five inches, and from _g_ as a
center the short arc _o o_ is swept.


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