19296An ESSAY
ſentation of the Figure which is in the ſecond
Plane, is likewiſe ſimilar to the Figure which is
in the Geometrical Plane, and the Lines com-
poſing this Appearance to the correſpondent
Lines in the ſecond Plane, as the Eye’s Diſtance
from the perſpective Plane, is to its Diſtance
from the before ſuppoſed Plane. But by means
of the Threads faſtned in the Manner aforeſaid,
we find the Repreſentation of a Figure, whoſe
Lines are in the aforenamed Proportion: 11118. Whence this Figure is the Perſpective ſought,
and is ſituated as it ought to be, with regard to
the Repreſentations of the Figures in the Geo-
metrical Plane; becauſe theſe Figures are ſo
ſlid, that the Appearance of the Perpen-
dicular in the Point B, is only a Point. The
ſaid Appearances are alſo in their proper Poſiti-
ons, becauſe the Line B Q, is made to coincide
with O N.
Plane, is likewiſe ſimilar to the Figure which is
in the Geometrical Plane, and the Lines com-
poſing this Appearance to the correſpondent
Lines in the ſecond Plane, as the Eye’s Diſtance
from the perſpective Plane, is to its Diſtance
from the before ſuppoſed Plane. But by means
of the Threads faſtned in the Manner aforeſaid,
we find the Repreſentation of a Figure, whoſe
Lines are in the aforenamed Proportion: 11118. Whence this Figure is the Perſpective ſought,
and is ſituated as it ought to be, with regard to
the Repreſentations of the Figures in the Geo-
metrical Plane; becauſe theſe Figures are ſo
ſlid, that the Appearance of the Perpen-
dicular in the Point B, is only a Point. The
ſaid Appearances are alſo in their proper Poſiti-
ons, becauſe the Line B Q, is made to coincide
with O N.
120.
For Solar Shadows in all Situations of the Per-
ſpective Plane.
ſpective Plane.
Prob. VII.
6.
To find the Repreſentations of the Shadows of
any Number of Points, being at the ſame Height
above the Geometrical Plane.
any Number of Points, being at the ſame Height
above the Geometrical Plane.
Find a Point in the Geometrical Plane, 22103.
is the Shadow of one of the given Points:
Tranſ-
poſe the Figures in the Geometrical Plane, ſo that
the Seat of the ſaid given Point coincides with
its Shadow; and the Line drawn through the
ſaid Seat, and the Shadow of the given Point,
coincides with its Prolongation. Then if ac-
cording to the Situation of the perſpective Plane,
the Repreſentations of the Seats of the
poſe the Figures in the Geometrical Plane, ſo that
the Seat of the ſaid given Point coincides with
its Shadow; and the Line drawn through the
ſaid Seat, and the Shadow of the given Point,
coincides with its Prolongation. Then if ac-
cording to the Situation of the perſpective Plane,
the Repreſentations of the Seats of the
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