PERSPECTIVE. 
so represented in perspective, provided 
they do not extend beyond 60” ; also, that 
in every instance perpendiculars in nature 
are so delineated in perspective. 
The reader will have seen, that the base- 
line, and the depth below it, give the mea- 
sure of the figure when obliqued. To 
render this more perfectly intelligible, let 
us say that it were necessary to place the 
sqtiare W, V, 13, T in perspective between 
W, V and X (fig. 4). This being a square 
is readily done ; the more so, as it is proxi- 
mate to the line ; because the quadrant TAV 
i.s so readily acted upon ; AV V being equal to 
V T. But say that it were needful to place 
the line T K (fig. 4) in perspective on the 
line V X. Diaw the quadrant T, AT; and 
the quadrant K, 10; the line AT, 1, drawn 
to 4>, will shew the place of T, and the line 
8, 2, will shew the place of K ; therefore 
the line T K will be found in perspective 
between the points 1 and 2 on the line 
A' X. Thus any line or object may be re- 
presented ; observing that the distance at 
which it stands below the base-line must be 
measured on the base-line; when, by draw- 
ing rays to the horizontal line, (whereon all 
the vanishing points must rest) its place on 
the oblique line, or scite, will be determin- 
ed. Some authors on this subject have di- 
reeled that the back ground should be li- 
mited by a semicircle, describing the half- 
horizon, and that all the vanishing points 
ought to be placed thereon. This, however 
well it may answer in a panoramic point of 
view, can never be so appropriate, as the 
horizontal line, in a picture which includes 
only the sixth part of a circle. 
AThat has been said relates entirely to 
mathematical perspective, and forms the 
basis of architectural design, and governs 
(though rather occultly) every kind of land- 
scape painting; with regard to the perspec- 
tive of living objects, and of varied nature, 
that can only be acquired by attention to 
models, and to the real figures. 
Perspective, aerial, is the art of giving 
a due diminution or degradation to the 
strength of the light, shade, and colours of 
objects, according to their different dis- 
tances, the quantity of light which falls on 
them, tind the medium through which they 
are seen. 
As the eye does not judge of the distance 
of objects entirely by their apparent size, 
but also by their strength of colours, and 
distinction of parts ; so it is not sufficient 
to give an object its due apparent bulk 
according to the rules of stereography, un- 
less at the same time it be expressed with 
that proper faintness and degradation of 
colour which the distance requires. Thus 
if the figure of a man, at a distance, were 
painted of a proper magnitude for the 
place, but with too great a distimdion of 
parts, or too strong colours, it would appear 
to stand forward, and seem proportionally 
less, so as to represent a dwarf situated 
nearer the eye, and out of the plane on 
which the painter intended it should stand. 
By the original colour of an object is 
meant that colour which it exhibits to the 
eye when duly exposed to it in a full open 
uniform light, at such a moderate distance 
as to be clearly and distinctly seen. This 
colour receives an alteration from many 
causes, the principal of which are the fol- 
lowing. 
1. From the objects being removed to a 
greater distance from the eye, whereby the 
rays of light which it reflects are less 
vivid, and the colour becomes more diluted 
and tinged, in some measure, by the faint 
bluish cast, or with the dimness or haziness 
of the body of air through which the rays 
pass. 
2. From the greater or less degree of 
light with which the object is enlightened ; 
the same original colour having a different 
appearance in the shades, trom what it has 
in the light, although at an equal distance 
from the eye, and teo in proportion to the 
strength of the light or shade. 
3. From the colour of the light itself 
which falls upon it, whether it be from the 
reflection of coloured light from any adja- 
cent object, or by its passage through a co- 
loured medium, which will exhibit a colour 
compounded of the original colour of the 
object, and the other accidental colours 
which the light brings with it. 
4. From the position of the surface of 
the object, or of its several parts with re- 
spect to the eye ; such parts of it appearing 
more lively and distinct than those which 
are seen obliquely. 
5. From the closeness or openness of the 
place where the object is situated ; the 
light being much more variously directed 
and reflected within a room, than in the 
open air. 
6. Some original colours naturally reflect 
light in a greater proportion than others, 
though equally exposed to the same degrees 
of it ; whereby their degradation at several 
distances will be different from tliat of other 
colours which reflect less liglit. 
From these several causes it happens that 
