III
The designer of the book, therefore, first determines his imposition and then tackles the details of composition. The first principles of composition do not require much discussion since they necessarily follow from the conventions of alphabetical printing in the Roman letter accepted by those for whom we are printing. The matter is relatively simple. First, it is certain that the eye cannot read with ease any considerable number of words composed of letters embodying sharply contrasted thicks and thins; secondly, it is none the less certain that the eye cannot agreeably read a mass of words composed even in a rightly constructed letter, if the lines are beyond a certain length. The most expert reader's eye cannot seize more than a certain number of words in a given size except in a proportionate length of line. Thirdly, practice proves that the size of the letter must be related to the length of line. Respect for these principles will generally protect the reader from the risk of "doubling" (reading the same line twice). The average line of words which the reader's eye can conveniently seize is between ten and twelve. Nevertheless, the typographer, while exerting himself to the utmost to respect this ocular truth, is daily confronted with the fact that unavoidable conditions make it impossible for him to secure a type of the duly related size, and that he is driven to use a relatively small type. To obviate here the risk of "doubling," he consistently inserts proportionate leads through the matter, so opening the lines that the eye comfortably travels and returns from beginning to end and from end to beginning.
The practice of leading, denounced in certain quarters as essentially evil, is an inevitable necessity to a large proportion of printing; and the skilled typographer, making the best use of his material, makes in turn, wise use of leads. The orthodox high-brow view that leads produce in every instance an unhappy weak-looking effect will not survive a wide experience. On the contrary, it will be found that their absence may effectively ruin even a composition in large type, so that it is true to say that the intelligent use of leading distinguishes the expert from the inexpert printer. A slight differentiation of type-face may make the practice advisable. Clearly, while a letter of the size now under the reader's eye, with fairly long ascenders and descenders, would not require leading unless set to a measure of more than 3-1/2 in., there exist letters with short descenders designed rather to sustain leading by rule than by exception. Baskerville's is a type to which leading is invariably an advantage. The problem of determining the amount to be given is not to be settled by considering only the ascenders or the body of the type, because breadth of letter is also a factor to be reckoned with—some letters are narrow in respect to their height, while others are wide. A composition in a round, open, wide letter, chosen because it is rather loose (that is to say, the space between the letters is greater, or appears greater, by reason of the curves of the c, o, e, g), gains in consistency when there is a satisfactory lead between the lines. It is often argued that loose setting is not admirable in itself; to which it might be replied that the printer is generally bound to carry out the instructions of his customer; often to respect the wishes of an artist who may be illustrating the work; and, not seldom, committed by the publisher to a paper-size dictated by irrelevant considerations.
Further, it is obvious that the space between words composed in a condensed letter may be less than that between words in a round, wide form of letter. Where there is no leading between the lines, and the composition is, for extrinsic reasons, necessarily tight, it may be an advantage to set leads between the paragraphs, even though this result in pages with uneven tails. In paragraphing, it is important to realize that the opening sentence of a work should automatically manifest itself as such. This may be secured by the use of the large initial letter; the printing of the first word in CAPITALS, or SMALL CAPITALS; CAPITALS and SMALL CAPITALS; or by setting the first word into the margin. On no account should the opening of a chapter be indented, since indention should mark (and always mark) the subsequent sections, i.e., the paragraphs, of the text. The abolition of paragraph-indentions is plainly an undesirable practice; nor is setting the first word in capitals or small capitals an agreeable substitute for the indention. The space of the indention should be sufficient to be noticeable.
As both measures must be related, displaying a proportion pleasing to the eye, the depth of the page follows from its width. It seems that the proportions of the oblong are more pleasing than those of the square; and as a horizontal oblong drives out the line to an impossible length, and a two-column arrangement is tedious, the vertical oblong has become the normal page.
Such are the elements of typography; and a volume built up of type-pages composed in accordance with them will be generally satisfactory. There remain only the page headings and the folio. By ranging the headings inside towards the gutter, to the left and right respectively, two pages are fixed as a unity; but they can also be ranged outside to the right and left, or they may be centered. The folio may be centered at the foot, or range either way at the top or bottom (preferably, for quicker reference, on the outside), but it cannot be centered at the top without cancelling the running page headline—only to be done by exception. The running headlines may be set in capitals of the text, in upper and lower-case of the text, or in a combination of capitals. Full-sized capitals overemphasize what is, after all, a repetitive page-feature inserted chiefly for the convenience of librarians and readers interested in the identification of leaves which have worked loose. If set in upper and lower-case, the headline loses in levelness, so that it seems well to employ SMALL CAPITALS; these are best separated by hair spaces, since the unrelieved rectangular structure and perpendicularity of capitals tend to defeat instantaneous recognition. Full-sized capitals may well be used for chapter headings, with the number of the chapter in smalls; both indications being hair-spaced.
The reader, travelling from the generally invariable blank at the end of a chapter to the beginning of the next, finds a dropped chapter head an agreeably consistent feature, which saves him from feeling suffocated or overpowered by the text.