The artists repository and drawing magazine: exhibiting the principles of the polite arts in their various branches (3.1789)

[ 53 ]
formed without the geometrical figure, by given mea-
sares, and angles.
PLATE V.
No. I. This example shews the method os putting in-
to perspebtive a right line, as A B ; or part of a right
line, as H I; or a simple point, as A. Having placed
(H L) the horizontal line, and determined the center
(C) and the distarice (Cl) I is the transposed place
of the natural eye. If A be considered as a point, unite
it to the ground line, by a right line in any direction at
pleasure (as at B) ] rule from I a line, parallel to this
line, towards H L (as near H) ; then is the point
where it slrikes H L the vanishing point to A B:
unite B to this point by a line, in some part of which
line will the representation os A be found. To ascer-
tain its exact place, unite A to I, the intersedtion of the
two lines marks the spot as at A. It is evident, that the
line A I may be determined by treating the point i as
we have already treated the point A ; which will give its
seat on the line B H at i. The representation of the whole
line A B is equally readily found, as appears-by the
figure
The direction of the original line is of no conse-
quence, or effedt; in every direction its parallel from I
mud be drawn to H L.
No. II. Is a variation from the former example, by
supposing the original line to be perpendicular to the
picture. The principal systematic lines are as before.
In this case, as the line A B or D E would naturally
vanish in C (which is its parallel), we are concerned
only to determine its length ; this is obtained in A B*
by