Watch and Clock Escapements | Page 8

to the spring _G_; but in case this
is done it would be better to make another spring like G without the
point j, and with the adjusting screw placed at l. In fitting pen and
pencil points to a spring like G it would probably be economical to
make them outright; that is, make the blades and screw for the ruling
pen and a spring or clamping tube for the pencil point.
CONSIDERATION OF DETACHED LEVER ESCAPEMENT
RESUMED.
We will now, with our improved drawing instruments, resume the
consideration of the ratchet-tooth lever escapement. We reproduce at
Fig. 16 a portion of diagram III, from Moritz Grossmann's "Prize Essay
on the Detached Lever Escapement," in order to point out the error in

delineating the entrance pallet to which we previously called attention.
The cut, as we give it, is not quite one-half the size of Mr. Grossmann's
original plate.
In the cut we give the letters of reference employed the same as on the
original engraving, except where we use others in explanation. The
angular motion of the lever and pallet action as shown in the cut is ten
degrees; but in our drawing, where we only use eight and one-half
degrees, the same mistake would give proportionate error if we did not
take the means to correct it. The error to which we refer lies in drawing
the impulse face of the entrance pallet. The impulse face of this pallet
as drawn by Mr. Grossmann would not, from the action of the engaging
tooth, carry this pallet through more than eight degrees of angular
motion; consequently, the tooth which should lock on the exit pallet
would fail to do so, and strike the impulse face.
We would here beg to add that nothing will so much instruct a person
desiring to acquire sound ideas on escapements as making a large
model. The writer calls to mind a wood model of a lever escapement
made by one of the "boys" in the Elgin factory about a year or two after
Mr. Grossmann's prize essay was published. It went from hand to hand
and did much toward establishing sound ideas as regards the correct
action of the lever escapement in that notable concern.
If a horological student should construct a large model on the lines laid
down in Mr. Grossmann's work, the entrance pallet would be faulty in
form and would not properly perform its functions. Why? perhaps says
our reader. In reply let us analyze the action of the tooth B as it rests on
the pallet A. Now, if we move this pallet through an angular motion of
one and one-half degrees on the center g (which also represents the
center of the pallet staff), the tooth B is disengaged from the locking
face and commences to slide along the impulse face of the pallet and
"drops," that is, falls from the pallet, when the inner angle of the pallet
is reached.
[Illustration: Fig. 16]
This inner angle, as located by Mr. Grossmann, is at the intersection of

the short arc i with the line g n, which limits the ten-degree angular
motion of the pallets. If we carefully study the drawing, we will see the
pallet has only to move through eight degrees of angular motion of the
pallet staff for the tooth to escape, because the tooth certainly must be
disengaged when the inner angle of the pallet reaches the peripheral
line a. The true way to locate the position of the inner angle of the
pallet, is to measure down on the arc i ten degrees from its intersection
with the peripheral line a and locate a point to which a line is drawn
from the intersection of the line g m with the radial line a c, thus
defining the inner angle of the entrance pallet. We will name this point
the point x.
It may not be amiss to say the arc i is swept from the center g through
the point u, said point being located ten degrees from the intersection of
the radial a c with the peripheral line a. It will be noticed that the inner
angle of the entrance pallet A seems to extend inward, beyond the radial
line a j, that is, toward the pallet center g, and gives the appearance of
being much thicker than the exit pallet _A'_; but we will see on
examination that the extreme angle x of the entrance pallet must move
on the arc i and, consequently, cross the peripheral line a at the point u.
If we measure the impulse faces of the two pallets _A A'_, we will find
them nearly alike in linear extent.
Mr. Grossmann, in delineating his exit pallet, brings the extreme angle
(shown at _4_) down to the