ne of the teeth of the escape wheel resting on the
pallet at the point _f_; and the escape wheel turning in the direction
of the arrow _j_. If we imagine a tooth as indicated at the dotted
outline at _D_, Fig. 6, pressing against a surface which coincides with
the radial line _p f_, the action would be in the direction of the line
_f h_ and at right angles to _p f_. If we reason on the action of the
tooth _D_, as it presses against a pallet placed at _f_, we see the
action is neutral.

[Illustration: Fig. 6]

ESTABLISHING THE CENTER OF PALLET STAFF.

[Illustration: Fig. 7]

With a fifteen-tooth escape wheel each tooth occupies twenty-four
degrees, and from the point _f_ to _e_ would be two and one-half
tooth-spaces. We show the dotted points of four teeth at _D D' D''D'''_.
To establish the center of the pallet staff we draw a line at
right angles to the line _p e'_ from the point _e_ so it intersects the
line _f h_ at _k_. For drawing a line at right angles to another line,
as we have just done, a hard-rubber triangle, shaped as shown at _C_,
Fig. 7, can be employed. To use such a triangle, we place it so the
right, or ninety-degrees angle, rests at _e_, as shown at the dotted
triangle _C_, Fig. 6, and the long side coincides with the radial line
_p e'_. If the short side of the hard-rubber triangle is too short, as
indicated, we place a short ruler so it rests against the edge, as shown
at the dotted line _g e_, Fig. 7, and while holding it securely down on
the drawing we remove the triangle, and with a fine-pointed pencil draw
the line _e g_, Fig. 6, by the short rule. Let us imagine a flat surface
placed at _e_ so its face was at right angles to the line _g e_, which
would arrest the tooth _D''_ after the tooth _D_ resting on _f_ had been
released and passed through an arc of twelve degrees. A tooth resting on
a flat surface, as imagined above, would also rest dead. As stated
previously, the pallets we are considering have equidistant locking
faces and correspond to the arc _l l_, Fig. 6.

In order to realize any power from our escape-wheel tooth, we must
provide an impulse face to the pallets faced at _f e_; and the problem
before us is to delineate these pallets so that the lever will be
propelled through an arc of eight and one-half degrees, while the escape
wheel is moving through an arc of ten and one-half degrees. We make the
arc of fork action eight and one-half degrees for two reasons--(1)
because mo