Mathematically
considered, the theoretical plane represented by the impulse face of
the tooth approaches parallelism with the plane represented by the
impulse face of the pallet, arrives at parallelism and instantly passes
away from such parallelism.
TO DRAW A PALLET IN ANY POSITION.
As delineated in Fig. 92, the impulse planes of the tooth and pallet are
in contact; but we have it in our power to delineate the pallet at any
point we choose between the arcs _p s_. To describe and illustrate the
above remark, we say the lines _B e_ and _B f_ embrace five degrees of
angular motion of the pallet. Now, the impulse plane of the pallet
occupies four of these five degrees. We do not draw a radial line from
_B_ inside of the line _B e_ to show where the outer angle of the
impulse plane commences, but the reader will see that the impulse plane
is drawn one degree on the arc _p_ below the line _B e_. We continue the
line _h h_ to represent the impulse face of the tooth, and measure the
angle _B n h_ and find it to be twenty-seven degrees.
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