esign of diapers and
wall patterns and hangings of all kinds. Nay, the first weaver of the
wattled fence discovered the principle of extension in design, and
showed its inseparable association with construction; and the builder
with brick or stone emphasizes it, producing the elements of linear
surface pattern, from the mechanical necessity of the position of the
joints of his structure. At a German railway station waiting-room I
noticed an effective adaptation of this principle as a wall decoration
in two blues upon a stone colour (see illustration, p. 128[fig077a]). We
may build upon such emphatic structural lines, either incorporating them
with the design motive, as in all rectangular wall diapers, or we may
suppress or conceal the actual constructive lines by placing the
principal parts or connections of our pattern over them, but one cannot
construct a satisfactory pattern to repeat and extend without them; for
these constructive lines or plans give the necessary organic life and
vigour to such designs, and are as needful to them as the trellis to the
tendrils of the vine (see illustration, p. 129[f077b]).

[Illustration (f077b): Surface Extension: Repeating Patterns Built Upon
(1) Square and (2) Circular Basis.]

The same principle is true of designs upon the curvilinear plan. The
mere repetition of the circle by itself gives us a simple geometric
pattern, and we are at liberty to emphasize this circular plan as the
main motive; or, as in the case of the rectangular plans, to treat it
merely as a basis, and develop free scroll motives upon it; or follow
it through its principal variations, as in the ogee, formed by dropping
out two intermediate semicircles; or the various forms of the scale
arrangement. These simple geometric plans are the most generally useful
as plans of designs intended for repetition and extension over space,
and they are always safe and sound systems to build upon, since a
geometric plan is certain to join comfortably if our measurements are
right.

[Illustration (f078): Surface Extension: Plan of a Drop Repeat.]

We may, however, often feel that we want something bolder and freer, and
start with a motive of sweeping-curves, non-geometric, but even then a
certain geometric relation will be necessary, or an equivalent for it,
since each curve must be counterbalanced in some way, though not
necessarily symmetrically, of course; and even where a square of
pattern--say to a wall-paper repeat