• Legibility and readability frequently confused and used interchangeably
• Spacing, type design, weight, set-width and x-height important factors
• Line and letting our elements that must not be treated lightly

Last month on this page, factors governing spacing were discussed, with particular emphasis on spacing between words. However, there are many other considerations which make the printed page legible and readable. Even these terms, legibility and readability, are frequently confused, and they often are used interchangeably.

By legibility we mean the rapid perception of letters or words. By readability we mean the ease with which letters or words can be read. While the type may be legible and design, its effect may be nullified by its use in badly composed lines and pages. Spacing thus becomes an important factor in the readability of type.

Other considerations concerned the design, weight, and set-width of the type, and its x-height–the relative size of the lower-case letter without ascender or descender. Links to these elements are line length and the letting, either of which should be discussed separately.

How long should a line of type be? This question is apparently as unanswerable as the old saw about the length of a piece of string (once used on so-called intelligence tests until somebody burst the bubble by saying that it was twice as long as from either and to the middle). Unfortunately, the printer’s dilemma continues. Witness the answers to this and the Composition Manual, the find text published by Printing Industry of America.

Varied Line-Lengths Suggested

In this value, no less than 11 recommendations are listed for the “ideal” line length of 10-point type, two-point lead it. The range, given by various authorities, varies from 13 to 31 picas, demonstrating clearly the lack of agreement even among experts.

Most printers have heard of one of the most common methods of determining line length, that is, to stay within the set with of an alphabetic and a half. This is a practical solution, because it takes care of the design of the type and its set-width. More recently, some typographers have extended this measure to two alphabet lengths.

Perhaps the best solution is to examine the problem itself, rather than to set up base hard-and-fast standard. In other words, the printer must consider the type in use, and the function of the individual job.

For example, if the type has a wide set-width, such as Century Expanded, the line can be wider than with Bodoni Book, which is some 20 per cent narrower. The design of the face also contributes to the selection of the length of line. Sans serifs, because they lack that prominent feature of legibility, the serifs, are less likely to be readable in long lines than standard romans. In addition they are poor risks due to their monotone strokes. Clearly then, varying factors must be considered in the apparently simple task of choosing a proper line length.

The function of the job is also of great importance, for reading habits vary under different conditions. Obviously, the termination of the line length and a placard should not be made by the same rule as that used for the measure in the pocketbook, designed to be read on a train. The printer, of course, has normal standards to depend upon in his selection, but no automatic procedure can govern all cases.

In the letting of lines, a number of variables must be reconciled. Line length both depends upon and governs a leading, paradoxical as this may seem. Here again no recognized procedure exists, although it has long been thought that 20 per cent of body size was sufficient lighting under ordinary circumstances.

The function of the job is even more important here than it is in apportioning line length. Leading can make a paragraph or page more inviting to read, but greater freedom is allowed in commercial printing or advertising typography than in the traditional book typography.

Wooing the Reader’s Attention

In commercial printing, the reader’s attention is being wooed. In a book, provided that normal principles of structure have been followed, the typographer does not have to be as concerned with attracting the reader. Normally, books are read for their subject matter and not for their appearance, although George Bernard Shaw once remarked that more costly books derived their value from the craft of the printer and not from the author’s genius.

A veritable "Father of the Waters" is this river of white space in a news story from the February 2 issue of the "Toronto Globe and Mail." Correspondent suggested, doubtfully, it may have been done to call attention of printers to event.

The design of the type also affects letting. For instance, the standard romans need less letting than the sans serifs and square serifs, normally must receive maximum leading to prevent vertical eye movement. The strong contrasts of Bodoni also give a vertical stress. Indeed, Bodoni himself used wide leading in most of his work.

The x-height of the type controls leading to an even greater degree than it controls line length, because types with long ascenders and descenders require less letting than those that are “full on the body.” In this respect the so-called legibility faces, designed primarily for newspapers and magazines, which use short measures, need a greater amount of letting an types such as Caslon, Garamond, and similar old-style faces with their roomier shoulders.

The relative weight of a type also has an effect on leading. Those faces with a light color, such as Baskerville and Cloister Light, appear at their best with less letting than type such as Bulmer, Scotch, Times Roman, and of course the bold versions of the standard faces.

Summing up, we see that many qualifying factors determine the line length and letting. Geoffrey Dowding recommends that a line of solid type contained 54 to 60 characters, which he says would be nine or ten words in English. This reasonable suggestion follows quite closely the two-alphabet length favored by some American typographers.

This article first appeared in “The Composing Room” column of the April 1955 issue of The Inland Printer.