In making this drawing we proceed as with Fig. 132 by establishing a
center for our radius of 10" outside of our drawing paper and drawing
the line _A A_ to such center and sweeping the arcs _a b c_. We
establish the point _e_, which represents the center of our cylinder, as
before. We take the space to represent the radial extent of the outside
of our cylinder in our dividers and from _e_ as a center sweep a fine
pencil line, represented by the dotted line _t_ in our drawing; and
where this circle intersects the arc _a_ we name it the point _s_; and
it is at this point the heel of our escape-wheel tooth must part with
the exit lip of the cylinder. From _e_ as a center and through the point
_s_ we draw the line _e l''_. With our dividers set to the radius of any
convenient arc which we have divided into degrees, we sweep the short
arc _d'_. The intersection of this arc with the line _e l''_ we name the
point _u_; and from _e_ as a center we draw the radial line _e u f'_. We
place the letter _f''_ in connection with this line because it (the
line) bears the same relations to the half shell of the cylinder shown
in Fig.
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