8537on PERSPECTIVE.
Point A parallel to the Baſe Line, and made e-
qual to B C. Now if from the Extremities of
the ſaid Line A L, Perpendiculars are let fall,
meeting the Baſe Line in the Points P and M,
and from theſe Points, Lines are drawn to the
Point of Sight V; then a N will likewiſe be 115, 16. the Perſpective of A L; and ſince P M is equal
to D E, a N will be likewiſe equal to G H, and
conſequently a N will be likewiſe equal to a I,
which is equal to G H.
qual to B C. Now if from the Extremities of
the ſaid Line A L, Perpendiculars are let fall,
meeting the Baſe Line in the Points P and M,
and from theſe Points, Lines are drawn to the
Point of Sight V; then a N will likewiſe be 115, 16. the Perſpective of A L; and ſince P M is equal
to D E, a N will be likewiſe equal to G H, and
conſequently a N will be likewiſe equal to a I,
which is equal to G H.
Method II.
57.
The ſame Things being given, as in the
precedent Method, about the Point A, as a
22Fig. 23. Center, and with the Radius B C, deſcribe the
Arc of a Circle L M, and draw the Line O L
from the Eye touching it; then about a, (which
is the Repreſentation of A) as a Center deſcribe
the Circular Arc G I touching the Line L O,
and cutting another Line drawn through a Per-
pendicular to the Baſe Line in the Point I: I
ſay the Point I is the Extremity of the Repre-
ſentation ſought.
precedent Method, about the Point A, as a
22Fig. 23. Center, and with the Radius B C, deſcribe the
Arc of a Circle L M, and draw the Line O L
from the Eye touching it; then about a, (which
is the Repreſentation of A) as a Center deſcribe
the Circular Arc G I touching the Line L O,
and cutting another Line drawn through a Per-
pendicular to the Baſe Line in the Point I: I
ſay the Point I is the Extremity of the Repre-
ſentation ſought.
Demonstration.
To prove this, let fall the Perpendiculars A L
and a G upon the Line O L, which will meet
the ſaid Line in the Points wherein it touches
the circular Arcs M L and G I.
and a G upon the Line O L, which will meet
the ſaid Line in the Points wherein it touches
the circular Arcs M L and G I.
Alſo aſſume D E in the Baſe Line equal to B C
or A L, and draw the Line D F; then through a,
draw a H parallel to the Baſe Line.
or A L, and draw the Line D F; then through a,
draw a H parallel to the Baſe Line.
Now let us conſider the Figure X, which re-
33Fig. 24. preſents a Plane paſſing through the Eye and
the Point A of the foregoing Figure, wherein
O f here, repreſents O F there; f e here, F
33Fig. 24. preſents a Plane paſſing through the Eye and
the Point A of the foregoing Figure, wherein
O f here, repreſents O F there; f e here, F