86, the draw is less even than twelve degrees. The angle _C a I_
remains constant, as shown at _C a' I'_, but the relation to the radial
_A G_ changes when the pallet moves through the angle _w C w'_, as it
must when locked. A tangential locking in the true sense of the meaning
of the phrase is a locking set so that a pallet with its face coinciding
with a radial line like _A G_ would be neutral, and the thrust of the
tooth would be tangent to the circle described by the locking angle of
the tooth. Thus the center _C_, Fig. 86, is placed on the line _w'_
which is tangent to the circle _s_; said line _w'_ also being at right
angles to the radial line _A G_.
The facts are, the problems relating to the club-tooth lever escapement
are very intricate and require very careful analysis, and without such
care the horological student can very readily be misled. Faulty
drawings, when studying such problems, lead to no end of errors, and
practical men who make imperfect drawings lead to the popular phrase,
"Oh, such a matter may be all right in theory, but will not work in
practice.
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