the Dead Escapement for Clocks. 339 
shape correctly in hardening, and to retain the acting part of the 
pallet perfectly hard. To obviate this difficulty, the pallet has 
sometimes been made a separate piece, with a short arm, by 
which it is fixed with two screws to the arm of the frame; but 
this is only to exchange one evil for another, for, independent 
of other disadvantages, which it is unnecessary to enumerate, it 
is very uncertain, with the pallets fixed in this manner, whether 
or not the rests of the pallets are concentric with the centre of the 
axis of the verge. The slightest deviation from its original direc- 
tion in the arm of the pallet, by hardening or any other cause, has 
the effect of removing the centre of the circle, forming the rests 
of the pallets, from the centre of the axis of the verge to some 
other place, the consequence of which is to render the escape- 
ment a recoil escapement. 4th, That the mode here recom- 
mended of constructing the pallets, offers a great facility for 
making the inclined planes of the pallets equal to one another, 
or of altering them as may be required ; and consequently the 
angle which the pendulum is led by one pallet, will be equal to 
the angle it is led by the other. 
Figs. 14 and 15, as before mentioned, represent the jointed 
pallet-frame in profile and in front, with all its parts complete, 
attached to the verge, and the pallets in their places. To Fig. 15 
is added the scape-wheel, and the pallets are represented in the 
situation in which they will appear, when the wheel has led the 
pallet to the extremity of the lead. The angles of lead (more par- 
ticularly noticed hereafter,) of the pallets being each supposed 
equal to an angle of 2°, it follows that the pendulum is led 1° on 
each side of the perpendicular line O P, by the action of the 
escapement, and that the wheel will escape when the pendulum 
vibrates the smallest quantity more than 1° on each side of the 
line it subtends when at rest. Now, supposing the total are of 
vibration of the pendulum to be 5°, that is, 2° 30’ on each side 
of the perpendicular, and the angle of lead of the pallets 2°; 
the tooth of the scape-wheel rests 3° on the rests of the pallets, 
1° 30' on each rest, during each vibration of the pendulum. the 
pendulum vibrating an angle of 5°. From the above, the great 
importance of the rests of the pallets being concentric to the 
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