This section is from the book "The Manufacture Of Boots And Shoes: Being A Modern Treatise Of All The Processes Of Making And Manufacturing Footgear", by F. Y. Golding. Also available from Amazon: The Manufacture Of Boots And Shoes.
The adapted System is founded upon the geometrical method, but is adapted to the various trade measurements used, while it retains the regularity of appearance, and conforms to the lasts. If it be thoroughly understood, it can be used for any unit grade, English or foreign, and for sets of lasts that have breaks in them, it is a very valuable method of grading. A method of locating the positions of measurements should be adopted, such as the one described on p. 114, or, better still, a table made from the positions located from the back on the size-stick principle. This will prevent the measurement of different places on the last and on the pattern. The positions of the toes, joints, instep, heel, ankle, and leg being indicated on the standard about to be graded, then the following mode will be used: Carefully mark round the standard upon a suitable sheet of paper an outline of the pattern to be graded, making the lines across as recommended, that have been previously taken from the last. For accuracy in this method it is imperative that the positions of measurement on the pattern and the last are identical, even if it be not to a table of location-distances. Select a suitable point as centre (which is usually either the seat of the pattern or the counter-height line), and from this point draw radial lines; in Fig. 153 will be the point selected for the present description. From this point * draw the line * Aa, and from the central radial point also make the line to C. From A mark either side as many sizes as you wish to grade above or below the standard size. At right angles to the base-line * Aa make lines meeting the line terminating in C. This will determine the length of the other sized standards. In the illustration the cross lines at the toes, joints, instep, etc., have been omitted, to make the plan clearer. The positions of the other lines, toes, joints, etc., are now to be found. They are obtained in the same way as those described for the geometrical system of grading. The widths are determined by taking them direct from the lasts, or from the scale, if working to a scale. In Fig. 153 X has been measured from x on the position-line found by the geometric. Y has also been got from the last. The instep, heel, ankle, top of leg, and height of standard have also been obtained in the same way. The grading of the parts may be done on the same stencil as the standard. Thev must be graded so as to Produce the same appearance and proportion as the original boot possessed. This has been alluded to on p. 180, and also illustrated on p. 91. The grading of the vamp on this method has been demonstrated in Fig. 153, where VT is the line of the front of the vamp of the standard. Through the height of vamp (which has been obtained as recommended) a line from X is drawn parallel to the crease-line of the standard vamp. Any other parts are obtained in the same way.
Some Errors in Patterns, and how Remedied. - An error often made in the cutting of patterns is that the toe of the pattern is sprung too much for the last. This makes the front seam curve shorter than that suitable, and by some is supposed to assist the laster in producing a better draft. It is, however, a false idea. It certainly imparts in the made-up boot a tension throughout the depth of the vamp, but it adds to the troubles of the laster in dealing with the upper round the feather, and if the material lasted be something of the nature of patent, it will be a matter of extreme difficulty to get a clearly lasted feather.
If the toe of the pattern be made dead, it reverses to an extent the effect of the previous error. The front seam is lengthened, the edge of the upper along the bottom is shortened, very often made so short that the waist is tight in lasting, and the linings do not sit clear when off the last. Another error often practised is the straightening of the front curve above the vamp. This throws a strain upon the front seam, but does not increase the length of the bottom edge of the upper when lasting. If not over-done, however, it is a useful way of remedying the falling in of the vamp or the front of the golosh caused through the curve being too sharp down the front of the pattern. Blocked fronted goods are often cut too acute in the front curve of the rounding and blocking pattern, and when this is the case, it may be remedied by adopting in a moderate way this practice of straightening the front curve. Shoe patterns are often curved at the top of the back quarterseam, with the idea of assisting the clipping properties. It is liable to cause a strain on the seam and to gall the foot of the wearer. Curves for the side seams of slippers, and the seams such as those used in Wellingtons, are often spoilt by not applying the principle of rounding or curving the seams according to the nature of the material. Patterns cut to formes produced on Soules or the mitre methods are often found to be too springy at the toe, and the front seam is too short, owing to the neglect of not making allowances for the openings of the slits when on the last. For instance, in Fig. 120, VN is correct, but TV is too springy, while for patent leathers the corner of the forme would be relatively more suitable. The tongues of such designs as the "Langtries" are usually too baggy, and this should be remedied by the use of the curved seam principle. It is often termed "draft." * Strap or bar shoes are often cut to pull across the instep rather than round the foot, somewhat in the direction of the heel-line. Lining patterns are very faulty in their allowance for stiffenings. The substance of the cover, its stretchiness, and the mode of making have to be fully weighed and allowed for. In the made-up boot very often the vamps, toecaps, etc., of the larger sizes look out of all proportion to the original sized boot, and this may be prevented by remembering that the relation of the parts of the made-up boot that are measured throughout their entire length on the imaginary axial line of the boot are proportioned to the length of the boot, while the wing and other portions that are not so measured are proportioned in relation to the distance round the last.