But study of the due
relation of the parts in good drawings will also master the situation.
A FEW EXPERIMENTS WITH OUR ANGLE-MEASURING DEVICE.
In using the little instrument for determining angular motion that we
have just described, care must be taken that the spring clamp which
embraces the pallet staff does not slip. In order to thoroughly
understand the methods of using this angle-measuring device, let us take
a further lesson or two.
We considered measuring the amount of lock on each pallet, and advised
the removal of the balance, because if we left the balance in we could
not readily tell exactly when the tooth passed on to the impulse plane;
but if we touch the fork lightly with an oiling tool or a hair broach,
moving it (the fork) carefully away from the bank and watching the arc
indicated by the hand _A_, Fig. 72, we can determine with great
exactness the angular extent of lock. The diagram at Fig. 75 illustrates
how this experiment is conducted. We apply the hair broach to the end of
the fork _M_, as shown at _L_, and gently move the fork in the direction
of the arrow _i_, watching the hand _A_ and note the number of degrees,
or parts of degrees, indicated by the hand as passed over before the
tooth is unlocked and passes on to the impulse plane and the fork flies
forward to the opposite bank.
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