Fig. 10, a and b
Fig. 11.
But you want to cut shaped pieces as
well as straight. You cannot break these directly the cut is made, but, holding the glass as in fig. 12, and pressing it firmly with the left thumb, jerk the tool up by little, sharp jerks of the fingers only, so as to tap along the underside of your cut. You will see a little silver line spring along the cut, showing that the glass is dividing; and when that silver line has sprung from end to end, a gentle pressure will bring the glass apart.
Fig. 12.
This upward jerk must be sharp and swift, but must be calculated so as only just to reach the glass, being checked just at the right point, as one hammers a nail when one does not want to stir the work into which the nail is driven. A pushing stroke, a blow that would go much further if the glass were not there, is no use; and for this reason neither the elbow nor the hand must move; the knuckles are the hinge upon which the stroke revolves.
| Fig. 13. | Fig. 14. |