*Project Gutenberg*. Public domain.

We have previously given instructions for drawing
the pallet locked; and to delineate the pallet after
five degrees of angular motion, we have only to conceive
that we substitute the line *s’* for the
line *b’*. All angular motions and
measurements for pallet actions are from the center
of the pallet staff at *B*. As we desire
to now delineate the entrance pallet, it has passed
through five degrees of angular motion and the inner
angle *s* now lies on the pitch circle of the
escape wheel, the angular space between the lines
*b’ s’* being five degrees, the line
*b’’* reducing the impulse face to
four degrees.

DRAWING AN ESCAPEMENT TO SHOW ANGULAR MOTION.

To delineate our locking face we draw a line at right
angles to the line *B b’’* from the
point *t*, said point being located at the intersection
of the arc *o* with the line *B b’’*.
To draw a line perpendicular to *B b’’*
from the point *t*, we take a convenient space
in our dividers and establish on the line *B b’’*
the points *x x’* at equal distances from
the point *t*. We open the dividers a little
(no special distance) and sweep the short arcs *x’’
x’’’*, as shown at Fig. 91.
Through the intersection of the short arcs *x’’
x’’’* and to the point *t*
we draw the line *t y*. The reader will
see from our former explanations that the line *t
y* represents the neutral plane of the locking face,
and that to have the proper draw we must delineate
the locking face of our pallet at twelve degrees.
To do this we draw the line *t x’* at twelve
degrees to the line *t y*, and proceed to outline
our pallet faces as shown. We can now understand,
after a moment’s thought, that we can delineate
the impulse face of a tooth at any point or place we
choose by laying off six degrees on the arc *m*,
and drawing radial lines from *A* to embrace
such arc. To illustrate, suppose we draw the radial
lines *w’ w’’* to embrace six
degrees on the arc *a*. We make these lines
contiguous to the entrance pallet *C* for convenience
only. To delineate the impulse face of the tooth,
we draw a line extending from the intersection of
the radial line *A’ w’* with the arc
*m* to the intersection of the arc *a* with
the radial line *A w’’*.

[Illustration: Fig. 91]

We next desire to know where contact will take place
between the wheel-tooth *D* and pallet *C*.
To determine this we sweep, with our dividers set
so one leg rests at the escape-wheel center *A*
and the other at the outer angle *t* of the entrance
pallet, the short arc *t’ w*. Where
this arc intersects the line *w* (which represents
the impulse face of the tooth) is where the outer
angle *t* of the entrance pallet *C* will
touch the impulse face of the tooth. To prove