A balance with all of
its weight as near the periphery as is consistent with strength, is what
is to be desired for best results. It is the moving matter composing the
balance, pitted against the elastic force of the hairspring, which we
have to depend upon for the regularity of the timekeeping of a watch,
and if we can take two grains' weight of matter from our roller table
and place them in the rim or screws of the balance, so as to act to
better advantage against the hairspring, we have disposed of these two
grains so as to increase the efficiency of the controlling power and not
increase the stress on the pivots.
[Illustration: Fig. 79]
We have deduced from the facts set forth, two axioms: (_a_) That we
should keep the weight of our balance as much in the periphery as
possible, consistent with due strength; (_b_) avoid excessive size from
the disturbing effect of the air. We show at _A_, Fig. 79, the shape of
the piece which carries the jewel pin. As shown, it consists of three
parts: (1) The socket _A_, which receives the jewel pin _a_; (2) the
part _A''_ and hole _b_, which goes on the balance staff; (3) the
counterpoise _A'''_, which makes up for the weight of the jewel socket
_A_, neck _A'_ and jewel pin.
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