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 these matters of illusion, for they are vital to the success of his labor. (See [¶ 116].)
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. (See exceptions, [¶ 119].)
These straight lines may be used where extremes are needed. (See pages [61] and [63].)
A short doorway, for instance, looks higher where the portière is hung in straight folds; so also with a cottage window.
