Corollary II.
Theorem III.
12.
If a Line parallel to the Perſpective Plane, be
view’d by two Eyes, both being in a Plane, parallel
to the perſpective Plane, the Repreſentations of the
ſaid Line will be equal.
view’d by two Eyes, both being in a Plane, parallel
to the perſpective Plane, the Repreſentations of the
ſaid Line will be equal.
If we ſuppoſe a Plane, parallel to the Per-
ſpective Plane, to paſs through the propoſed
Line, this Proportion will be had; viz. As 119. Diſtance of the Eyes from this Plane, is to their
Diſtance from the Perſpective Plane, ſo is the
given Line to the Repreſentation thereof. But
the three firſt Terms of this Proportion are
the ſame for each of the Eyes, which are
in one and the ſame Plane parallel to the Per-
ſpective Plane: Therefore, the fourth Term of
the Proportion will likewiſe be the ſame in both
Caſes: Which was to be demonſtrated.
ſpective Plane, to paſs through the propoſed
Line, this Proportion will be had; viz. As 119. Diſtance of the Eyes from this Plane, is to their
Diſtance from the Perſpective Plane, ſo is the
given Line to the Repreſentation thereof. But
the three firſt Terms of this Proportion are
the ſame for each of the Eyes, which are
in one and the ſame Plane parallel to the Per-
ſpective Plane: Therefore, the fourth Term of
the Proportion will likewiſe be the ſame in both
Caſes: Which was to be demonſtrated.