3413on PERSPECTIVE.
and the Objects ſtand;
and the Perſpective
Plane, as a Window between the Spectator and
the Objects, in which the Objects are requir’d
to be repreſented. But, in Practice, this Matter
muſt be quite otherwiſe conceiv’d; which I
ſhall now endeavour to explain as clear as poſ-
ſible.
Plane, as a Window between the Spectator and
the Objects, in which the Objects are requir’d
to be repreſented. But, in Practice, this Matter
muſt be quite otherwiſe conceiv’d; which I
ſhall now endeavour to explain as clear as poſ-
ſible.
Suppoſe then, that a Painter has a mind to
draw upon his Perſpective Plane, or Picture,
(whoſe Bigneſs is as he thinks fit) a Proſpect of
a Country, wherein are Trees, Houſes, Rivers, & c.
Now, from what has been ſaid, this Country
will be his Geometrical Plane; and he ought to
conſider his Perſpective Plane as a Window, up-
on which the Points thro’ which the Rays com-
ing from all the Points of the Objects towards
the Eye, muſt be found. But theſe Interſections
of the Rays and the Window cannot be deter-
min’d, unleſs by Lines being drawn in the Geo-
metrical Plane to the Baſe Line.
draw upon his Perſpective Plane, or Picture,
(whoſe Bigneſs is as he thinks fit) a Proſpect of
a Country, wherein are Trees, Houſes, Rivers, & c.
Now, from what has been ſaid, this Country
will be his Geometrical Plane; and he ought to
conſider his Perſpective Plane as a Window, up-
on which the Points thro’ which the Rays com-
ing from all the Points of the Objects towards
the Eye, muſt be found. But theſe Interſections
of the Rays and the Window cannot be deter-
min’d, unleſs by Lines being drawn in the Geo-
metrical Plane to the Baſe Line.
Now, it is impoſſible for Painters to draw Lines
of this Nature on the Ground; wherefore they
uſe another more convenient Geometrical Plane
thus. At the Foot of their Perſpective Plane,
they place a Plane, upon which are drawn in
Minature the Baſes of Houſes and Trees, which
are in the Country to be repreſented; and the
Seats of the Points which, in the Objects, are
elevated above the Country; always obſerving,
that there be the ſame Diſpoſition between the
Objects and their different Parts, upon this new
Geometrical Plane, as the Objects truly have in
the Country to be repreſented.
of this Nature on the Ground; wherefore they
uſe another more convenient Geometrical Plane
thus. At the Foot of their Perſpective Plane,
they place a Plane, upon which are drawn in
Minature the Baſes of Houſes and Trees, which
are in the Country to be repreſented; and the
Seats of the Points which, in the Objects, are
elevated above the Country; always obſerving,
that there be the ſame Diſpoſition between the
Objects and their different Parts, upon this new
Geometrical Plane, as the Objects truly have in
the Country to be repreſented.
Now, to determine the Magnitude of the
Space the Figures muſt take up upon this Geo-
metrical Plane, a Painter muſt firſt chuſe the
Diſpoſition of his Eye in reſpect to the
Space the Figures muſt take up upon this Geo-
metrical Plane, a Painter muſt firſt chuſe the
Diſpoſition of his Eye in reſpect to the