DOI Seite / Zitierlink:
https://doi.org/10.11588/diglit.18826#0107
lect ii.]
on perspective.
75
PLATE XXVI.
Suppofing thefe examples fufficient to explain the
manner of treating folid bodies, &c. we proceed now
to fhew the nature of other objects. It has already
been obferved in Lecture II. that all rotatory ob-
jects form a circle at their circumference, of which
the hinge is the center: on this principle are the
doors in this example put into perspective.
Fig. 1. C is the center, H L the horizontal line;
the breadth of the door is marked on the ground line,
as AB; and AD is the depth it muft be in the room.
Draw D H, cutting A C in E; draw from E, a line
parallel to the ground line, as EF; which is cut by
B C in F, and determines the width of the door at
that part (if half open); F ruled to H will give e for
the edge of the door, if fuppofed fhut: the femi-
circle on the floor is formed by the ordinary methods.
From the bottom of the door E, to the circumference
of the circle, gives the (ituation of the door: the
fame line continued to H L gives its vanifhing point,
as at I: perpendiculars from the bottom of the door,
and its edge, are cut by a line from I, to determine
its height. In Fig. 2. the door is feen open fome-
what differently: the fame procefs gives K for its
vanifhing point ; as is clear by the figure.
Fig. 3. Is a reprefentation of a trap-door in the
floor: A B its breadth; which of courfe is the front
of the aperture. The door C, and its hinge D, are
found exactly as the fame parts in the foregoing
figures; g is one vanifhing point for the quarter of
a circle, correfponding to the fquare A, D, e, f.
If this figure, and thofe of the former numbers
are turned, and viewed fideways, they mutually ii*
luftrate each other.
PLATE
on perspective.
75
PLATE XXVI.
Suppofing thefe examples fufficient to explain the
manner of treating folid bodies, &c. we proceed now
to fhew the nature of other objects. It has already
been obferved in Lecture II. that all rotatory ob-
jects form a circle at their circumference, of which
the hinge is the center: on this principle are the
doors in this example put into perspective.
Fig. 1. C is the center, H L the horizontal line;
the breadth of the door is marked on the ground line,
as AB; and AD is the depth it muft be in the room.
Draw D H, cutting A C in E; draw from E, a line
parallel to the ground line, as EF; which is cut by
B C in F, and determines the width of the door at
that part (if half open); F ruled to H will give e for
the edge of the door, if fuppofed fhut: the femi-
circle on the floor is formed by the ordinary methods.
From the bottom of the door E, to the circumference
of the circle, gives the (ituation of the door: the
fame line continued to H L gives its vanifhing point,
as at I: perpendiculars from the bottom of the door,
and its edge, are cut by a line from I, to determine
its height. In Fig. 2. the door is feen open fome-
what differently: the fame procefs gives K for its
vanifhing point ; as is clear by the figure.
Fig. 3. Is a reprefentation of a trap-door in the
floor: A B its breadth; which of courfe is the front
of the aperture. The door C, and its hinge D, are
found exactly as the fame parts in the foregoing
figures; g is one vanifhing point for the quarter of
a circle, correfponding to the fquare A, D, e, f.
If this figure, and thofe of the former numbers
are turned, and viewed fideways, they mutually ii*
luftrate each other.
PLATE