If we take the "Roman" types--the letters with which we are most familiar--and draw them in single pencil strokes (as a child does when it "learns its letters"), we get a rough representation of their Essential Forms (see diagram, fig. 142).
Such letters might be scratched with a point in wax or clay, and if so used in practice would give rise to fresh and characteristic developments,[53] but if we take a "square cut" pen which will give a thin horizontal stroke and a thick vertical stroke (figs. 10 and 40), it will give us the "_straight-pen_," or simple written, essential forms of these letters (fig. 143).
These essential forms of straight-pen letters when compared with the plain line forms show a remarkable degree of interest, brought about by the introduction of the thin and thick strokes and gradated curves, characteristic of pen work.
Certain letters (A, K, M, N, V, W, X, Y, and k, v, w, x, y) in fig. 143 being composed chiefly of oblique strokes, appear rather heavy. They are lightened by using a naturally "slanted" pen which produces thin as well as thick oblique strokes. And the verticals in M and N are made thin by further slanting the pen (fig. 144).
To our eyes, accustomed to a traditional finish, all these forms--in figs. 143 and 144, but particularly the slanted pen forms--look incomplete and unfinished; and it is obvious that the thin strokes, at least, require marked terminals or _serifs_. [p242]
_Finishing-Strokes._--The pen naturally produces a variety of finishing-strokes--"heads," "feet," serifs, &c.--each type of which strongly characterises the alphabet in which it is employed.
(b) _Straight (or curved) strokes_, thick or thin according to the direction of the pen.
(c) _Triangular "heads"_ (and "feet"), straight or slanted, and more or less curved and sharpened.
(d) _Thin finishing-curves_, horizontal or oblique.
To give uniformity to the various letters of an alphabet it is necessary to treat similar parts as consistently as possible throughout (see No. 5, p. 239). And the remarkable way in which "heads" impart a "family likeness" to letters closely resembles the same phenomenon among human beings (see pp. 324, 254).
If we consider the four types of serif, _as applicable to straight-pen writing_, we find-- [p245]