THE 2½-FOOT MODULE (STANDARD MODULE)
Figure 59 shows a scale analysis of the southern transept
arm of the Church of the Plan of St. Gall. The surface area
covered by this part of the Church forms a square, each
side of which is equal to the width of the nave, i.e., 40 feet.
In the second and third drawing shown on this page, this
square is subdivided into sixteen strips, first from north to
south, then from east to west; in the last drawing the two
systems are combined.
The experiment proves that all the internal area divisions
of the southern transept arm are conceived as
multiples of a 2½-foot square. The passageway that gives
access to the crypt is three units wide and sixteen units long
(7½ × 40 feet), the platform on which the altar of St.
Andrew stands is three units wide and ten units long
(7½ × 25 feet). The steps and benches have a standard
width of one unit (2½ feet) and vary in length between five,
six, and ten units (12½ feet, 15 feet, and 25 feet). The
intervals between the steps and benches likewise can be
brought into a system of logical relationships, if interpreted
as multiples of a 2½-foot square.
An analysis of the adjacent area of the Dormitory of the
Monks (fig. 60.A) enables us to establish this point with
even greater persuasiveness. The complicated layout of the
beds in this building is inconceivable without the use of a
carefully constructed system of auxiliary construction lines.
It is easily understandable if it is conceived as being developed
within a grid of 2½-foot squares (demonstrated in fig.
60.C). The overall analysis of Cloister and Church suggests
that the building was meant to be sixteen 2½-foot units wide
and thirty-four 2½-foot units long (40 × 85 feet). Each bed
is one unit wide and three units long (2½ × 7½ feet), with
the exception of a small number of beds near the two gable
walls which had to be shortened to leave sufficient room for
the entrances and exits located in these walls. A glance at
the drawings shown in figure 60.B discloses that the boundaries
of the beds do not in all cases coincide with the
boundaries of the underlying squares. The beds that lie at
right angles to the long wall straddle the grid lines with
their center axis. This suggests the possibility of the use of
an even smaller module, which we shall discuss later.
The superimposition of the square grid on the original
drawing (fig. 60.B) reveals the means by which the draftsman,
in copying this building, extended its length by one
unit beyond what it was meant to be through an accumulation
of small errors. The center group of beds in the northern
half of the Dormitory has a length of twelve 2½-foot
modules. The corresponding group of beds in the southern
half of the building is thirteen 2½-foot modules long. It is
obvious that they were meant to be of identical size. Figure
60.B shows with great precision those places where the
draftsman took on these additional increments of space
(first and second transverse row in the southern half of the
building). This was probably due to two slight and almost
imperceptible shifts in the relation of the original parchment
to the tracing sheets. By the time the draftsman had
reached the end of the second row of beds, he had inadvertently
picked up an excess of an entire module. This lengthened
the Dormitory from thirty-four to thirty-five standard
modules, or from 85 feet (length of the original) to 87½ feet
(length of the copy).[364]
In analyzing the dimensional layout of this as well as any
other building of the Plan it is important that the overall
dimensions of each respective structure be ascertained by
its relation to neighboring or superordinate units before an
attempt is made to decipher its internal relationships.
