Aligning a Rocky Road
The history of baselines
A friend writing about the nature of vertical type alignment and interline spacing with digital-only typesetting put me on the path to research something I’d long wondered about in the era of metal type (~1450–1980s): How could you set a line of type that mixed typefaces from the same or different foundries and keep a consistent baseline?
The baseline is the invisible horizontal line on which the bottom of the body of characters sit in the Latin alphabet and many other scripts, whether the bottom of an uppercase letter or the main body of a lowercase one. This is true for handwriting, scribal hands, and letterpress type — as well as all the phototype and digital type that followed in printing and onscreen. The baseline is one of the foundations of legibility, allowing letters to be read in a flowing fashion along a horizontal line our minds construct.
So how did type foundries keep a consistent baseline? They did not. At least for most of the first four and a half centuries of printing before industrial scale had fully set in and before standardization became keenly important as an element of efficiency and productivity.
Many printers initially made their own type or contracted or bought it from goldsmiths and others. That worked perhaps well enough within an individual press. As Talbot Baines Reed wrote in A History of the Old English Letter Foundries (1887):
Imagining, as we do, that the moulds of the first printers were of a primitive construction, and, though conceived on true principles, were adjusted to the various sizes of letter they had to cast more by eye than by rule, it is easy to understand that founts would be cast on no other principle than that of ranging in body and line and height in themselves, irrespective of the body, height and line of other founts used in the same press.
That was obviously not tenable as scale increased. Type foundries arose just decades after printing’s rise in Europe, and rapidly took on more importance as a centralized supplier of a key ingredient of printing. (Printers also worked out methods to purchase or rent some parts of type production and make their own duplicates, authorized or otherwise.)
