Figs. 6 and 7.
Fig. 8.
How to Cut Glass.—Hold the cutter as shown in the illustration (fig. 5), a little
sloping towards you, but perfectly upright laterally; draw it towards you, hard enough to make it just bite the glass. If it leaves a mark you can hardly see it is a good cut (fig. 10b), but if it scratches a white line, throwing up glass-dust as it goes, either the tool is faulty, or you are pressing too hard, or you are applying the pressure to the wheel unevenly and at an angle to the direction of the cut (fig. 10a). Not that you can make the wheel move sideways in the cut actually;
it will keep itself straight as a ploughshare keeps in its furrow, but it will press sideways, and so break down the edges of the furrow, while if you exaggerate this enough it will actually leave the furrow, and, ceasing to cut, will "skid" aside over the glass. As to pressure, all cutters begin by pressing much too hard; the tool having started biting, it should be kept only just biting while drawn along. The cut should be
almost noiseless. You think you're not cutting because you don't hear it grate, but hold the glass sideways to the light and you will see the silver line quite continuous.
Having made your cut, take the glass up; hold it as in fig. 11, press downward with the thumbs and upward with the fingers, and the glass will come apart.
Fig. 9.