We open the dividers a little (no special distance) and
sweep the short arcs _x'' x'''_, as shown at Fig. 91. Through the
intersection of the short arcs _x'' x'''_ and to the point _t_ we draw
the line _t y_. The reader will see from our former explanations that
the line _t y_ represents the neutral plane of the locking face, and
that to have the proper draw we must delineate the locking face of our
pallet at twelve degrees. To do this we draw the line _t x'_ at twelve
degrees to the line _t y_, and proceed to outline our pallet faces as
shown. We can now understand, after a moment's thought, that we can
delineate the impulse face of a tooth at any point or place we choose by
laying off six degrees on the arc _m_, and drawing radial lines from _A_
to embrace such arc. To illustrate, suppose we draw the radial lines
_w' w''_ to embrace six degrees on the arc _a_. We make these lines
contiguous to the entrance pallet _C_ for convenience only. To delineate
the impulse face of the tooth, we draw a line extending from the
intersection of the radial line _A' w'_ with the arc _m_ to the
intersection of the arc _a_ with the radial line _A w''_.
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