The Face-Gage is a Square Notch cut with a File into the edge of a thin Plate of Steel, Iron, or Brass, the thickness of a piece of common Latton, and the Notch about an English deep. There be three of these Gages made, for the Letters to be cut on one Body; but they may be all made upon one thin Plate, the readier to be found, as at D. As first, for the Long Letters; Secondly, for the Assending Letters; And Thirdly, for the Short-Letters. The Length of these several Notches, or Gages, have their Proportions to the Body they are cut to, and are as follows. We shall imagine (for in Practice it cannot well be perform’d, unless in very large Bodies) that the Length of the whole Body is divided into forty and two equal Parts.
The Gage for the Long-Letters are the length of the whole Body, viz. forty and two equal Parts. The Gage for the Assending Letters, Roman and Italica, are five Seventh Parts of the Body, viz. thirty Parts of forty-two, and thirty and three Parts for English Face. The Gage for the Short-Letters are three Seventh Parts of the whole Body, viz. eighteen Parts of forty-two for the Roman and Italica, and twenty two Parts for the English Face.
It may indeed be thought impossible to divide a Body into seven equal Parts, and much more difficult to divide each of those seven equal Parts into six equal Parts, which are forty-two, as aforesaid, especially if the Body be but small; but yet it is possible with curious Working: For seven thin Spaces may be Cast and Rubb’d to do it. And for dividing each of the thin Spaces into six equal Parts, you may Cast and Rub Full Point . to be of the thickness of one thin Space, and one sixth part of a thin Space: And you may Cast and Rub : to be the thickness of one thin Space, and two sixth parts of a thin Space: And you may Cast and Rub , to be the thickness of one thin Space, and three sixth parts of a thin Space: And you may Cast and Rub - to be the thickness of one thin Space, and four sixth parts of a thin Space: And you may Cast and Rub ; to be the thickness of one thin Space, and five sixth parts of a thin Space.
The reason why I propose . to be Cast and Rubb’d one sixth part thicker than a thin Space, is only that it may be readily distinguished from : , - ; which are two sixth parts, three sixth parts, four sixth parts, five sixth parts thicker than a thin Space. And for six sixth parts thicker than a thin Space, two thin Spaces does it.
The manner of adjusting these several Sixth Parts of Thicknesses is as follows. You may try if six . exactly agree, and be even with seven thin Spaces; (or, which is all one, a Body) for then is each of those six . one sixth part thicker than a thin Space, because it drives out a thin Space in six thin Spaces. And you may try if six : be equal to a Body and one thin Space; for then is each : two sixth parts thicker than a thin Space. If six , be equal to nine thin Spaces, then each , is three sixth parts of a thin Space thicker than a thin Space. If six - be equal to ten thin Spaces, then each - is four sixth parts of a thin Space thicker than a thin Space. If six ; be equal to eleven thin Spaces, then each ; is five sixth parts of a thin Space thicker than a thin Space.
Now, as aforesaid, a thin Space being one seventh part of the Body, and the thin Space thus divided, you have the whole Body actually divided into forty and two equal parts, as I have divided them in my Drafts of Letters down the Sides, and in the Bottom-Line.
Though I have thus shewed how to divide a thin Space into six equal Parts, yet when the Letter to be Cut proves of a small Body, the thin Space divided into two equal Parts may serve: If it prove bigger, into three or four equal Parts: And of the largest Bodies, they may be divided into six, as aforesaid.
If now you would make a Gage for any number of thin Spaces and Sixth Parts of a thin Space, you must take one thin Space less than the number of thin Spaces proposed, and add . : , - ; according as the number of sixth Parts of a thin Space require; and to those complicated Thicknesses you may file a square Notch on the edge of the thin Plate aforesaid, which shall be a standing Gage or Measure for that number of thin Spaces and sixth Parts of a thin Space.
All the Exception against this way of Measuring is, that thin Spaces cast in Metal may be subject to bow, and so their Thicknesses may prove deceitful. But, in Answer to that, I say, you may, if you will, Cast I for two thin Spaces thick, e for three thin Spaces thick, S for four thin Spaces thick, L for five thin Spaces thick, D for six thin Spaces thick, or any other Letters near these several Thicknesses, as you think fit; only remember, or rather, make a Table of the number of thin Spaces that each Letter on the Shank is Cast for. And by complicating the Letters and Points, as aforesaid, you will have any Thickness, either to make a Gage by, or to use otherwise.
On the other Edge of the Face-Gage you may file three other Notches, of the same Width with those on the former Edge, for the Long, the Assending, and Short-Letters. But though the two sides of each of these Notches are parallel to each other, yet is not the third side square to them, but hath the same Slope the Italick hath from the Roman; as you may see in the Figure at b b b.