This counterpoise also makes up for the
passing hollow _C_ in the guard roller _B_, Fig. 80. As the piece _A_
is always in the same relation to the roller _B_, the poise of the
balance must always remain the same, no matter how the roller action is
placed on the staff. We once saw a double roller of nearly the shape
shown at Fig. 79, which had a small gold screw placed at _d_, evidently
for the purpose of poising the double rollers; but, to our thinking, it
was a sort of hairsplitting hardly worth the extra trouble. Rollers for
very fine watches should be poised on the staff before the balance is
placed upon it.
[Illustration: Fig. 80]
We shall next give detailed instructions for drawing such a double
roller as will be adapted for the large model previously described,
which, as the reader will remember, was for ten degrees of roller
action. We will also point out the necessary changes required to make it
adapted for eight degrees of fork action. We would beg to urge again the
advantages to be derived from constructing such a model, even for
workmen who have had a long experience in escapements, our word for it
they will discover a great many new wrinkles they never dreamed of
previously.
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