Letters and words huddled together so that they are not readily recognized at a glance do not make easy reading. On the other hand, very wide spacing does not necessarily result in a proportionate increase of legibility; it may even produce results as confusing as very thin spacing.

A general rule affecting wide spacing is that the average distance between the words in the line should be less than the distance between the lines themselves. Notice in the above example how the words group themselves up and down the page rather than in order along the line for the eye to follow. Note also how wide spaces between the words form distinct, irregular streaks up and down the page to lead the eye away from its course along a single line at a time.

Wide spacing for easy reading has little advantage unless the lines are leaded out in equal proportion.

Double-leaded lines are well spaced with an average of an en quad. When this is used the limit of space would be the double 3-space, while the thin space would be the single 3-space.

An average spacing wider than the en quad is rarely ever necessary in roman lower-case matter even if the lines are separated with more than the double leads. The only excuse for the wider spacing is the necessity for making words and syllables fill the line.

In some kinds of composition wide spacing and wide leading are desirable. Wide measures and ample white space up and down the page naturally call for open spacing of type lines. Large advertisements, wall cards, placards, and other forms intended to be read at a distance farther away than the book or magazine in the hand, are properly wide-spaced and wide-leaded. Extremes in openness, however, are not safe to follow. A study of the work of the leading designers in typography will show a compact grouping of both words and lines which gives unity and orderliness with ample readability. In contrast with this the disconnected, patchy, scattered effects shown in commonplace type composition will prove that habitual wide-spacing is often unnecessary.