on 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
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.

##
74.
Method
II.

57. The ſame Things being given, as in the

precedent Method, about the Point A, as a

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.

##
75.
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.

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.

Now let us conſider the Figure X, which re-

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 E