11656An ESSAY
through I, and the Extremity of the propoſed
Line; and therefore the Perſpective of this Ex-
tremity is in the Line L H; which was to be
demonſtrated.
Line; and therefore the Perſpective of this Ex-
tremity is in the Line L H; which was to be
demonſtrated.
Note, if F H had been aſſumed, the one half,
or one third, & c. of what it is; then it is mani-
feſt that R Q muſt alfo have been taken 1119. to the one half, or third Part, & c. of C E.
or one third, & c. of what it is; then it is mani-
feſt that R Q muſt alfo have been taken 1119. to the one half, or third Part, & c. of C E.
Method. III.
71.
Forinclined Lines not meeting the Geometrical
Plane.
Plane.
Let A and B be the Seats of the Extremities of
22Fig. 37. the given Line. Let X repreſent a Plane paſſing
through the given Line perpendicular to the
Geometrical Plane. Likewiſe let M N in this
Plane, repreſent the Line whoſe Perſpective is re-
quir’d; and let C N and P M be perpendicular to
the Geometrical Plane: Whence P C repreſents
A B, and conſequently is equal thereto.
22Fig. 37. the given Line. Let X repreſent a Plane paſſing
through the given Line perpendicular to the
Geometrical Plane. Likewiſe let M N in this
Plane, repreſent the Line whoſe Perſpective is re-
quir’d; and let C N and P M be perpendicular to
the Geometrical Plane: Whence P C repreſents
A B, and conſequently is equal thereto.
Operation.
Find the Point I , the Perſpective of a 3350.
above the Point A, the Height of C N;
and
draw the Line B S, from the Point B, to the
Station Point I, cutting the Baſe Line in E; and
from the Point I, draw a Line to the accidental
Point F; which cut by a Perpendicular to the
Baſe Line, raiſed at the Point E; and then I T
will be the Appearance ſought.
draw the Line B S, from the Point B, to the
Station Point I, cutting the Baſe Line in E; and
from the Point I, draw a Line to the accidental
Point F; which cut by a Perpendicular to the
Baſe Line, raiſed at the Point E; and then I T
will be the Appearance ſought.
Method IV.
72.
For inclined Lines parallel to the perſpective
Plane.
Plane.
zoom in
zoom out
zoom area
full page
page width
set mark
remove mark
get reference
digilib