audience from seeing the ropes and pulleys hanging from the
gridiron--the box set more nearly mimics reality than the open
set, which calls upon the imagination of the audience to supply
the realities that are entirely lacking or only hinted at.

The painted canvas units which are assembled to make the box set
are called "flats." A flat is a wooden frame about six feet six
inches wide and from twelve to eighteen feet long, covered with
canvas and, of course, painted with any scene desired. It differs
from a wing in being only one-half the double frame; therefore it
cannot stand alone.

Upon the upper end of each flat along the unpainted outer edge
there is fastened a rope as long as the flat. Two-thirds of the
way up from the bottom of the corresponding edge of the matching
flat there is a "cleat," or metal strip, into which the rope, or
"lash-line" is snapped. The two flats are then drawn tight together
so that their edges match evenly and the lash-line is lashed through
the framework to hold the flats firmly together.

While one flat may be a painted wall, the next may contain a doorway
and door, another a part of an ornamental arch, and still another
a window, so, when the various flats are assembled and set, the
box set will have the appearance of a room containing doors and
windows and even ornamental arches. The most varied scenes can
thus be realistically set up.

In the rear of open doors there are usually wings, or perhaps
flats, [1] painted to represent the walls of hallways and adjoining
rooms and they are called "interior backings." Behind a door