An Analysis of the Lever Escapement | Page 2

mm., which is
equal to the breadth of an ordinary human hair; it is a degree in both
cases, but the difference is very great, therefore a degree cannot be
associated with any actual measurement until the radius of the circle is
known. Degrees are generated from the center of the circle, and should
be thought of as to ascension or direction and relative value. Circles
contain four right angles of 90° each. Degrees are commonly measured
by means of the protractor, although the ordinary instruments of this
kind leave very much to be desired. The lines can be verified by means
of the compass, which is a good practical method.
It may also be well to give an explanation of some of the terms used.
Drop equals the amount of freedom which is allowed for the action of
pallets and wheel. See Z, Fig. 1.
Primitive or Geometrical Diameter.--In the ratchet tooth or English
wheel, the primitive and real diameter are equal; in the club tooth wheel
it means across the locking corners of the teeth; in such a wheel,
therefore, the primitive is less than the real diameter by the height of
two impulse planes.
Lock equals the depth of locking, measured from the locking corner of
the pallet at the moment the drop has occurred.

Run equals the amount of angular motion of pallets and fork to the
bankings after the drop has taken place.
Total Lock equals lock plus run.
A Tangent is a line which touches a curve, but does not intersect it. AC
and AD, Figs. 2 and 3, are tangents to the primitive circle GH at the
points of intersection of EB, AC, and GH and FB, AD and GH.
Impulse Angle equals the angular connection of the impulse or ruby pin
with the lever fork; or in other words, of the balance with the
escapement.
Impulse Radius.--From the face of the impulse jewel to the center of
motion, which is in the balance staff, most writers assume the impulse
angle and radius to be equal, and it is true that they must conform with
one another. We have made a radical change in the radius and one
which does not affect the angle. We shall prove this in due time, and
also that the wider the impulse pin the greater must the impulse radius
be, although the angle will remain unchanged.
Right here we wish to put in a word of advice to all young men, and
that is to learn to draw. No one can be a thorough watchmaker unless
he can draw, because he cannot comprehend his trade unless he can do
so.
We know what it has done for us, and we have noticed the same results
with others, therefore we speak from personal experience. Attend night
schools and mechanic's institutes and improve yourselves.
The young workmen of Toronto have a great advantage in the Toronto
Technical School, but we are sorry to see that out of some 600 students,
only five watchmakers attended last year. We can account for the
majority of them, so it would seem as if the young men of the trade
were not much interested, or thought they could not apply the
knowledge to be gained there. This is a great mistake; we might almost
say that knowledge of any kind can be applied to horology. The young
men who take up these studies, will see the great advantage of them

later on; one workman will labor intelligently and the other do blind
"guess" work.
We are now about to enter upon our subject and deem it well to say, we
have endeavored to make it as plain as possible. It is a deep subject and
is difficult to treat lightly; we will treat it in our own way, paying
special attention to all these points which bothered us during the many
years of painstaking study which we gave to the subject. We especially
endeavor to point out how theory can be applied to practice; while we
cannot expect that everyone will understand the subject without study,
we think we have made it comparatively easy of comprehension.
We will give our method of drafting the escapement, which happens in
some respects to differ from others. We believe in making a drawing
which we can reproduce in a watch.

AN ANALYSIS OF THE LEVER ESCAPEMENT.
The lever escapement is derived from Graham's dead-beat escapement
for clocks. Thomas Mudge was the first horologist who successfully
applied it to watches in the detached form, about 1750. The locking
faces of the pallets were arcs of circles struck from the pallet centers.
Many improvements were made upon it until to-day it is the best form
of escapement for a general purpose watch, and when made on
mechanical principles is