If the
locking face of the entrance-pallet stone at _C_ was made to conform to
the radial line _A b_, the lock of the tooth _D_ at _o_ would be "dead";
that is, absolutely neutral. The tooth _D_ would press the pallet _C_ in
the direction of the arrow _x_, toward the center of the pallet staff
_B_, with no tendency on the part of the pallet to turn on its axis _B_.
Theoretically, the pallet with the locking face cut to coincide with the
line _A b_ would resist movement on the center _B_ in either direction
indicated by the double-headed arrow _y_.
A pallet at _C_ with a circular locking face made to conform to the arc
_g_, would permit movement in the direction of the double-headed arrow
_y_ with only mechanical effort enough to overcome friction. But it is
evident on inspection that a locking face on the line _A b_ would cause
a retrograde motion of the escape wheel, and consequent resistance, if
said pallet was moved in either direction indicated by the double-headed
arrow _y_.
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