Let us ſuppoſe the perſpective Plane continu-
ed, C D the Horizontal Line, and O the Eye
denoted in the Horizontal Plane. It is evi-
dent by Conſtruction, that the Line G F 1177. tinued, paſſes through the Eye O; produce the
Line G S a, until it meets the Horizontal Line
in D, and draw the Line O D. Let fall the
Perpendicular G N R, from the Point G upon
the Horizontal Line, which interſect in R, by
the Line O R, paſſing through the Eye parallel
to the Horizontal Line. Now by Conſtruction,
G M is {1/3} of M N; and conſequently it is {1/4} of
G N; M Z is likewiſe {1/4} of N R: Therefore
ed, C D the Horizontal Line, and O the Eye
denoted in the Horizontal Plane. It is evi-
dent by Conſtruction, that the Line G F 1177. tinued, paſſes through the Eye O; produce the
Line G S a, until it meets the Horizontal Line
in D, and draw the Line O D. Let fall the
Perpendicular G N R, from the Point G upon
the Horizontal Line, which interſect in R, by
the Line O R, paſſing through the Eye parallel
to the Horizontal Line. Now by Conſtruction,
G M is {1/3} of M N; and conſequently it is {1/4} of
G N; M Z is likewiſe {1/4} of N R: Therefore