108, where the tooth
_D_, after dropping from the pallet _C_, is arrested at the position
shown by the dotted outline. We designate this arc by the term "fall,"
and we measure this motion by its angular extent, as shown by the dotted
radial lines _i f_ and _i g_. As we have explained, this fall should
only extend through an arc of one and a half degrees, but by close
escapement matching this arc can be reduced to one degree, or even a
trifle less.
[Illustration: Fig. 108]
We shall next describe an instrument for holding the escape wheel and
pallets while adjusting them. As shown at Fig. 107, the fork _A'_ is
banked a little close and the jewel pin as shown would, in some
portions, rub on _C'_, making a scraping sound.
HOW TO MAKE AN ESCAPEMENT MATCHING TOOL.
[Illustration: Fig. 109]
A point has now been reached where we can use an escapement matcher to
advantage. There are several good ones on the market, but we can make
one very cheaply and also add our own improvements.
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