the line
_c D_, say, for illustration, to correspond to the line _c c'_ (leaving
the pallet center at _D_), we would have a strong draw and also a cruel
engaging friction.

If, however, we removed the engaging tooth, which we have just conceived
to be at _c_, to the point _k_ on the arc _a' a'_, Fig. 88, the pallet
center _D_ would then represent a tangential locking, and a neutral
pallet face would coincide with the radial line _A k'_; and a locking
face with twelve degrees draw would coincide nearly with the line _l_.
Let us next analyze what the effect would be if we changed the pallet
center to _h'_, Fig. 88, leaving the engaging tooth still at _k_. In
this instance the line _l l_ would then coincide with a neutral locking
face, and to obtain the proper draw we should delineate the locking face
to correspond to the line _k n_, which we assume to be twelve degrees
from _k l_.

It is not to be understood that we insist on precisely twelve degrees
draw from a neutral plane for locking faces for lever pallets. What we
do insist upon, however, is a "safe and sure draw" for a lever pallet
which will hold a fork to the banks and will also return it to such
banks if by accident the fork is moved away. We are well aware that it
takes lots of patient, hard study to master the complications of the
club-tooth lever escapement, but it is every watchmaker's duty to
conquer the problem. The definition of "lock," in the detached lever
escapement, is the stoppage or arrest of the escape wheel of a watch
while the balance is left free or detached to perform the greater
portion of its arc of vibration. "Draw" is a function of the locking
parts to preserve the fork in the proper position to receive and act on
the jewel pin of the balance.

It should be borne in mind in connection with "lock" and "draw," that
the line of thrust as projected from the locked tooth of the escape
wheel should be as near tangential as practicable. This maxim applies
particularly to the entrance pallet. We would beg to add that
practically it will make but little odds whether we plant the center of
our pallet staff at _C_ or _h_, Fig. 87, provided we modify the locking
and impulse angles of our pallets to conform to such pallet center. But
it will not do to arrange the parts for one center and then change to
another.

PRACTICAL HINTS FOR LEVER ESCAPEMENTS.

Apparently there seems to be a belief with very many watchmakers that
there is a set of shorth