the hand _B_.

[Illustration: Fig. 105]

[Illustration: Fig. 106]

A good way to get up the parts shown in Fig. 106 is to take a disk of
thick sheet brass about 1" in diameter and insert in it a piece of brass
wire about 1/4" diameter and 3/8" long, through which drill axially a
hole to receive the wire _k_. After the jaws _B''_ are clamped on the
pallet staff, we set the index arc _C_ so the hand _B'_ will indicate
the angular motion of the pallet staff. By placing the index hand _B_
on the balance staff we can get at the exact angular duration of the
engagement of the jewel pin in the fork.

Of course, it is understood that this instrument will also measure the
angles of impulse and lock. Thus, suppose the entire angular motion of
the lever from bank to bank is ten degrees; to determine how much of
this is lock and how much impulse, we set the index arc _C_ so that the
hand _B'_ marks ten degrees for the entire motion of the fork, and when
the escapement is locked we move the fork from its bank and notice by
the arc _C_ how many degrees the hand indicated before it passed of its
own accord to the opposite bank. If we have more than one and a half
degrees of lock we have too much and should seek to remedy it. How? It
is just the answers to such questions we propose to give by the aid of
our big model.

DETERMINATION OF "RIGHT" METHODS.

"Be sure you are right, then go ahead," was the advice of the celebrated
Davie Crockett. The only trouble in applying this motto to watchmaking
is to know when you are right. We have also often heard the remark that
there was only one right way, but any number of wrong ways. Now we are
inclined to think that most of the people who hold to but one right way
are chiefly those who believe all ways but their own ways are wrong.
Iron-bound rules are seldom sound even in ethics, and are utterly
impracticable in mechanics.

We have seen many workmen who had learned to draw a lever escapement of
a given type, and lived firm in the belief that all lever escapements
were wrong which were not made so as to conform to this certain method.
One workman believes in equidistant lockings, another in circular
pallets; each strong in the idea that their particular and peculiar
method of designing a lever escapement was the only one to be tolerated.
The writer is free to confess that he has seen lever escapements of both
types, that is, circular pallets and equidistant lockings, which gave
excel