ich is
supposed to also pass through the center of the pallet staff. The
intersection of the line _A B_ with the arc _a_ we term the point _d_,
and from this point we lay off on said arc _a_ thirty degrees each side
of said intersection, and thus establish the points _c b_. From _A_,
through the point _c_, we draw the line _A c c'_. On the arc _a a_ and
two and a half degrees to the left of the point _c_ we establish the
point _f_, which space represents half of the thickness of the entrance
pallet. From _A_ we draw through the point _f_ the line _A f f'_. From
_f_, and at right angles to said line _A f_, we draw the line _f e_
until it crosses the line _A B_.

Now this line _f e_ is tangent to the arc _a_ from the point _f_, and
consequently a locking placed at the point _f_ is a true tangential
locking; and if the resting or locking face of a pallet was made to
coincide with the line _A f'_, such locking face would be strictly
"dead" or neutral. The intersection of the line _f e_ with the line _A
B_ we call the point _C_, and locate at this point the center of our
pallet staff. According to the method of delineating the lever
escapement by Moritz Grossmann the tangent line for locating the center
of the pallet staff is drawn from the point _c_, which would locate the
center of the pallet staff at the point _h_ on the line _A B_.

Grossmann, in delineating his locking face for the draw, shows such face
at an angle of twelve degrees to the radial line _A f'_, when he should
have drawn it twelve degrees to an imaginary line shown at _f i_, which
is at right angles to the line _f h_. To the writer's mind this is not
just as it should be, and may lead to misunderstanding and bad
construction. We should always bear in mind the fact that the basis of a
locking face is a neutral plane placed at right angles to the line of
thrust, and the "draw" comes from a locking face placed at an angle to
such neutral plane. A careful study of the diagram at Fig. 88 will give
the reader correct ideas. If a tooth locks at the point _c_, the
tangential thrust would be on the line _c h'_, and a neutral locking
face would be on the line _A c_.

NEUTRAL LOCKINGS.

To aid in explanation, let us remove the pallet center to _D_; then the
line of thrust would be _c D_ and a neutral locking face would coincide
with the line _m m_, which is at right angles to the line _c D_. If we
should now make a locking face with a "draw" and at an angle to