15173on PERSPECTIVE.
Point in reſpect to each other, in the before ſup-
poſed Plane. Therefore the Line o F anſwers
@kewiſe to the Line in the ſaid Plane imagined
to be parallel to the propoſed Lines; and con-
ſequently the Point F, is that wherein the
ſaid Parallel meets the Perſpective Plane; and
therefore it is the accidental Point ſought.
poſed Plane. Therefore the Line o F anſwers
@kewiſe to the Line in the ſaid Plane imagined
to be parallel to the propoſed Lines; and con-
ſequently the Point F, is that wherein the
ſaid Parallel meets the Perſpective Plane; and
therefore it is the accidental Point ſought.
Note, Iſ the accidental Point T of Perpendi-
culars to the Geometrical Plane be found, the
Operation of this Problem may be ſhorten’d, in
drawing the Line T D, which will neceſſarily
paſs thro’ the Point N, and then the Point o will
be found by the Interſection of the Arc O o,
and a Semi-circle, whoſe Diameter is T D.
culars to the Geometrical Plane be found, the
Operation of this Problem may be ſhorten’d, in
drawing the Line T D, which will neceſſarily
paſs thro’ the Point N, and then the Point o will
be found by the Interſection of the Arc O o,
and a Semi-circle, whoſe Diameter is T D.
Problem VI.
89.
To find the Perſpective of one or more Lines
inclin’d to the Geometrical Plane.
inclin’d to the Geometrical Plane.
Let A be the Foot of a Line inclin’d to the
11Fig. 48. Geometrical Plane, and a its Repreſentation.
Now determine, by Means of the Triangle C P E
according to the Manner lay’d down for 2269. Perſpective Plane when ſuppoſed perpendicular,
the Length A B of the Direction of the propoſed
Line. This being done, find the Point X the 3382. ſpective of a Point above the Geometrical Plane
by the Length of P E; and then a X will be the
Perſpective ſought.
11Fig. 48. Geometrical Plane, and a its Repreſentation.
Now determine, by Means of the Triangle C P E
according to the Manner lay’d down for 2269. Perſpective Plane when ſuppoſed perpendicular,
the Length A B of the Direction of the propoſed
Line. This being done, find the Point X the 3382. ſpective of a Point above the Geometrical Plane
by the Length of P E; and then a X will be the
Perſpective ſought.
Method II.
90.
To ſolve this Problem by the Accidental Points
of inclined Lines, and their Directions.
of inclined Lines, and their Directions.
Let AB be the Direction of an inclin’d Line;
D
44Fig. 48. the Accidental Point of the Directions, & F that
44Fig. 48. the Accidental Point of the Directions, & F that
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