THE POINT SYSTEM
Some time prior to the year 1450 Gutenberg invented the casting of metal type in molds. As the art of printing advanced, many new sizes were cast, but no attempt was made to cast them with a uniform gradation in size and it was difficult to build up one size of body to equal another; that is, justify them.
To obviate this, Fournier, in 1737, advocated a method of casting type according to some unit. The size known as pica was in use in various countries in Europe, and was considered a standard size. Taking the pica as a basis he divided it into twelve parts, each of which he called a point. He chose one-twelfth of a pica as the unit because there existed five sizes of type between pica and nonpareil. As nonpareil was just half the size of pica, this made the succession of sizes seven, eight, nine, ten, and eleven points, any of which could be justified with another by the use of material made to the same unit.
The United States Typefounders’ Association finally adopted it in 1887. It is the only system in use in first-class offices today.
It is popularly supposed that six picas equal one inch. This is approximately so, but not absolutely, for six picas measure but .99648 of an inch. The American pica runs about three points less than 72 lines to the foot. Its actual measurement is .16608 of an inch. One-twelfth of this, or one point, is, therefore .01384 of an inch.
When calculating the amount of type contained in any piece of composed matter, it is measured up in ems, and this em, or unit, is the em of the body.
The square of each size of type is called the em of that body. Thus, the em of six-point is six points square; the em of eight-point is eight points square; and so on.