We now set our dividers to the radius of any
convenient arc which we have divided into degrees, and from _g_ as a
center sweep the short arc _l l_, and from the intersection of this arc
with the line _g k'_ we lay off sixteen degrees on the said arc _l_ and
establish the point _n_, from _g_ as a center draw the radial line _g
n'_. Take ten degrees from the same parent arc and establish the point
_m_, then draw the line _g m'_. Now the arc on the circles _h j_ between
the lines _g n'_ and _g m_ limits the extent of the exit lip of the
cylinder and the arc between the lines _g k'_ and _g m'_ represents the
locking surface of the cylinder shell.
[Illustration: Fig. 134]
To delineate the U arms we refer to Fig. 135. Here, again, we draw the
arc _a b c_ and delineate a tooth as before. From the point _e_ located
at the heel of the tooth we draw the radial line _e e'_. From the point
_e_ we lay off on the arc _a_ five degrees and establish the point _p_;
we halve this space and draw the short radial line _p' s'_ and _p s_.
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