Robson, William: Grammigraphia; or the Grammar of Drawing. (London, 1799)

11

cular Line. Then he discovers in what proportionate part
his eye is situate in the space that he intends for the Real
Perspective Plane, and marks this upon the Line, in a
corresponding proportion. In this place he draws-a
Horizontal Line, which forms the Horizontal Plane.
The intersection of these is the point of sight.

REPRESENTATION

OF THE

Perspective Plane.

3

'-3
a

P-
u

C

S

>

M
o

Eye of the observer,
or point of sight.

Height of the obsei\er/s eye, or Jl
Horizontal.

1



Foot of the observer, or Ground Line-