with the pallet
action, we would be all right; and so we would, but frequently this
bringing of the roller and fork to agree is not so easily accomplished.

It is chiefly toward this end the Waltham fork is made adjustable, so it
can be moved to or from the roller, and also that we can allow the
pallet arms to be moved, as we will try and explain. As we set the
bankings the pallets are all right; but to test matters, let us remove
the hairspring and put the balance in place. Now, if the jewel pin
passes in and out of the fork, it is to be supposed the fork and roller
action is all right. To test the fork and roller action we close the
banking a little on one side. If the fork and jewel pin are related to
each other as they should be, the jewel pin will not pass out of the
fork, nor will the engaged tooth drop from that pallet. This condition
should obtain on both pallets, that is, if the jewel pin will not pass
out of the fork on a given bank the tooth engaged on its pallet should
not drop.

We have now come to the most intricate and important problems which
relate to the lever escapement. However, we promise our readers that if
they will take the pains to follow closely our elucidations, to make
these puzzles plain. But we warn them that they are no easy problems to
solve, but require good, hard thinking. The readiest way to master this
matter is by means of such a model escapement as we have described. With
such a model, and the pallets made to clamp with small set-screws, and
roller constructed so the jewel pin could be set to or from the staff,
this matter can be reduced to object lessons. 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.