111. A doorway looks wider that has at the top a drapery which crosses in one complete curved sweep. A side-wall is larger apparently if along the frieze line long, wide loops or festoons are arranged. The same wall is more contracted and higher if treated in arrow-point forms of design.
The decorator should study
112. Perpendicular lines contract the wall space and extend the apparent height of a room; horizontal lines shorten the apparent height of the ceiling and lengthen the width of the room.
These straight lines may be used where extremes are needed.
A short doorway, for instance, looks higher where the portière is hung in straight folds; so also with a cottage window.
113. Every decorator who handles fabrics, every cabinetmaker who lays out the woodwork of a room, every stained glass window maker, should appreciate one fact: A line which is finished at the top or bottom, or both, with acute angles appears longer than the line that is finished top and bottom with an obtuse or right angle. It is the same with the finish of a wall frieze.
If the wall frieze ends abruptly, it is foreshortened; if it is finished by angles, the height of the room is apparently greater.
114. It is the same way with curves; given two lines of equal length and enclose one with convex and the other with concave curves, and the line enclosed convex will appear longer.
115. In dress a collar brought down to an acute angle in the front of the waist gives height effect, whereas a perfectly straight collar around the neck reduces the apparent height and gives width effect.
116. The use of arches should be studied. A space that is arched looks wider than it actually is, for the eye unconsciously follows the lines of the arch, and a distance or width effect is the result. The same space treated with a straight line is quickly bridged. The same space treated with lines that come to an angle looks narrower, for the reason that the eye becomes focused by the apex of the angle, and a height effect, not a breadth effect, is the result.
117. This illusion is best shown in the illustrations of the parallel lines that are crossed diagonally, with the result that the lines no longer look parallel because of the angles. Nevertheless, they are parallel, and the lines running diagonally at the bottom of this page are also parallel.
We present two practical illustrations of illusion in the use of lines. They represent the side-walls of two rooms of the same dimensions, but showing apparently different proportions, the perpendicular lines making the side-wall look higher and the horizontal lines making the side-wall look lower.
The length of the wall space is shortened, moreover, by the perpendicular lines and lengthened by the horizontal lines.
118. No period expresses more clearly the joy of curves as opposed to the severity of straight lines than that voluptuous period of Louis XV known as Rococo. It was a profligate era, an era of pleasure, and the appended illustration of part of a frieze is in no way exaggerated, but a true example of a common expression.
119. Distinct perpendicular lines give height effect, but they also narrow the apparent width of a wall space. It is best to have such line effects indistinct unless they they are intended to reduce the breadth effect of the pattern and neutralize a squat tendency.
Indistinct perpendiculars give height effect, and do not reduce the wall width.