For the reason that the vest is cut off below the waist, it can be cut on the square of 20 without piecing the pattern. But on a coat this cannot be done without piecing the pattern, and in order to obtain a draft or a pattern, without lap or piecing, the square of 20 is transformed into an angle of 15 deg., which contains the square of 17½ as for a vest, to which is added one-half for one extra seam, and which one-half more causes the squares of a frock coat to be 18 and 20½. And for reasons explained further on in this article, and in Dia. [III], a three-seamed sack must have the same squares as that of a frock coat of five seams.
The following points must be well observed: Dia. [II] has a square of 18, or half an inch extra on the plumb line base, which half an inch is allowed for one extra seam. The square of 17½ would answer the same purpose if each side piece and each forepart was allowed one extra seam; but this would cause the pattern to be pieced, or allowance would have to be made for one seam, which will always be found troublesome, and for this reason the square is enlarged to 18. But, to be more definite, the square should be 17½ and half an inch for all sizes, because if ½ an inch is allowed for a seam, this seam requires the same for all sizes. Perhaps ⅜ inch will do the same, or maybe better for a snug fit, particularly for fine work, where ⅜ of an inch is amply sufficient for a seam; but I call it ½ an inch for the reason that ¼ of an inch more or less in an entire coat is nothing, particularly when we must admit that no two cutters will take the same measure, and that very few cutters are able to take the same breast measure twice with the same result, if done so in using a blank tape.
Though the square of 18 will result in a square of 20½, we find that if we observe Dia. [II] correctly, the back square, which ends at point 15, on the center of back, sinks below line 11¼ in front, and becomes larger and consequently a reduction is made at that line between the back and side piece, in order to re-establish the square of 20. Again, if we observe Dia. [III], or the combination of frock and sack (and the vest as well,) we find that by turning the sidepiece forward at the waist it will turn backward about ½ inch at the shoulder blade, and although the top of the sidepiece and back lap ½, the square remains 18 for a three-seamed sack coat, the same as for a frock. The fact that I did not observe this simple point at the beginning, but made the square of a three-seamed sack ½ less than a frock coat, caused me to devote years in making alterations.
Dia. [III] is the best combination of frock, sack and vest, which I have been able to secure in 10 years of diligent study. Though the vest is not shown on it, because too many lines spoil the illustration, but anybody may observe the sameness in Dia. [XII]. Now, supposing the vest to be put in Dia. [III], we simply reduce its square ½ under the arm to make it 17½ and place the height of back at 14. The combination places the different backs at the following height above line 9. Frocks at 14¼, vests at 14, and sacks at 13½. The squares of 18 and 20½ are, of course, for a coat, but this does not destroy the principle of cutting a vest over the same pattern, simply reducing it ½ inch in width under the arm, and cutting the top of the back ½ lower, or 3¾, as shown in the Vest Dia.
Neither the square of 20 nor the square of 17½, nor the angle of 15 deg., nor any other angle or square, will fit the body precisely, either of which must be adjusted to the requirements of the form; but when we know what a certain square or angle represents, and how they harmonize with the slopes of the body, we can very easily deduct or add to, as the case may require.
Now, although certain garments require more or less in the square, I will, in comparing, always mention the squares of 17½ and 20 as on a vest, for the reason that line 11¼ meets line 9 at its center—that is, at the center of the square of 20—from which point all calculations are made for turning or changing the lines over the back. The square of 17½, with the angle of 15 deg. attached in front, produces both squares 17½ and 20 on this particular spot, though the square of 20 is broken on line 9; and within the squares of 17½ and 20 all calculations are made in the article on “[Narrow and Broad Backs].” By the terms: square of 17½, or 18, or 20, etc., I mean to say that the distance from the centre of the back to a certain base in front is such a distance. It may be that if I should say: a right angle, so and so far from back to front, would be better grammar, but I think, a square of so and so much will be fully as well, and may be better understood by the majority of cutters and tailors.
