143. Here the line _m_ represents the locking face of the
jewel and the line _o_ the clearance to free the escaping tooth, the
angle at _n_ being about fifty-four degrees. This angle (_n_) should
leave the rounding of the stone intact, that is, the rounding of the
angle should be left and not made after the flat faces _m o_ are ground
and polished. The circular space at _I_ is filled with an aluminum
pin. The sizes shown are of about the right relative proportions; but
we feel it well to repeat the statement made previously, to the effect
that the detent to a chronometer cannot well be made too light.
[Illustration: Fig. 141]
[Illustration: Fig. 142]
[Illustration: Fig. 143]
The so-called gold spring shown at _H_, Figs. 141 and 142, should also
be as light as is consistent with due strength and can be made of the
composite metal used for gold filled goods, as the only real benefit to
be derived from employing gold is to avoid the necessity of applying oil
to any part of the escapement.
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