point the radial line _A c'_. To the right of the point _a_ we lay off
five degrees and establish the point _d_. To illustrate the underlying
principle of our circular pallets: with one leg of the dividers set at
_B_ we sweep through the points _c a d_ the arcs _c'' a'' d''_.

From _B_ as a center, we continue the line _B a_ to _f_, and with the
dividers set at five inches, sweep the short arc _e e_. From the
intersection of this arc with the line _B f_ we lay off one and a half
degrees and draw the line _B g_, which establishes the extent of the
lock on the entrance pallet. It will be noticed the linear extent of
the locking face of the entrance pallet is greater than that of the
exit, although both represent an angle of one and a half degrees.
Really, in practice, this discrepancy is of little importance, as the
same side-shake in banking would secure safety in either case.

[Illustration: Fig. 19]

The fault we previously pointed out, of the generally accepted method of
delineating a detached lever escapement, is not as conspicuous here as
it is where the pallets are drawn with equidistant locking faces; that
is, the inner angle of the entrance pallet (shown at _s_) does not have
to be carried down on the arc _d'_ as far to insure a continuous pallet
action of ten degrees, as with the pallets with equidistant locking
faces. Still, even here we have carried the angle _s_ down about half a
degree on the arc _d'_, to secure a safe lock on the exit pallet.


THE AMOUNT OF LOCK.

If we study the large drawing, where we delineate the escape wheel ten