But a third way is to cut the shape of each piece of glass out in cartridge-paper; and to do this you put the cut-line down over a sheet of "continuous-cartridge" or "cartoon" paper, as it is called, and press along all the lines with a style or hard pencil, so as to make a furrow on the paper beneath; then, after removing the cut-line, you place a sheet of ordinary window-glass below the paper and cut out each piece, between the "furrows" leaving a full 1/16 of an inch. This sixteenth of an inch represents the "heart" or core of the future lead; it is the distance which the actual bits of glass lie one from the other in the window. You must use a very sharp penknife, and you will find that, cutting against glass, each shape will have quite a smooth edge; and round this you can cut with your diamond.
This method, which is far the most accurate and craftsmanly way of cutting glass, is best used with the actual diamond:
in that case you feel the edge of the paper all the time with the diamond-spark; but in cutting with the wheel you must not rest against the edge of the paper; otherwise you will be sure to cut into it. Now, whichever of all these processes you employ, remember that there must be a full 1/16 of an inch left between each piece of glass and all its neighbours.
The reason why you leave this space between the pieces is that the core of the lead is about that or a little less in thickness: the closer the glass fits to this the better, but no part of the glass must go nearer to its neighbour than this, otherwise the work will be pressed outwards, and you will not be able to get the whole of the panel within its proper limits.
Fig. 34.
Fig. 34 is an illustration of various kinds and sizes of lead; showing some with the glass inserted in its place.
By all means make your leads yourself, for many of those ready made are not lead at all, or not pure lead. Get the parings of sheet lead from a source you can trust, and cast them roughly in moulds as at fig. 35. Fig. 36 is the shears by which the strips may be cut; fig. 37 is the lead-mill or "vice" by which they are milled and run into their final shape; fig. 38 the "cheeks" or blocks through
which the lead passes. The working of such an instrument is a thing that is understood in a few minutes with the instrument itself at hand, but it is cumbrous to explain in writing, and not worth while; since if you purchase such a thing, obviously the seller will be there to explain its use. Briefly,—the handle turns two wheels with milled edges 1/16 of an inch apart; which, at one motion, draw the lead between them, mill it, and force it between the two "cheeks" (fig. 38), which mould the outside of the lead in its passage. These combined movements, by a continuous pressure, squeeze out the strip of lead into about twice its length; correspondingly decreasing its thickness and finishing it as it goes.
