adius 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 90deg. 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