Place a piece of window glass flat on the table, pour a little kerosene on the spot to be bored, clasp the file near the end, press the end down hard on the spot and turn it back and forth with a gouging motion (Fig. 87). You twist the file just as you would twist an awl to force it into hard wood.

You will soon penetrate the surface; use plenty of kerosene and continue the boring until you are nearly through; then turn the plate over and start a hole on the other side to meet the one you have made.

Fig. 86. Cutting a pane of glass

Do not rush things ; it will take you ten or fifteen minutes to bore through ordinary window glass.

Bore a hole in a bottle in the same way, except that the boring is all from the outside.

If the end of the file becomes dull, break off a small piece, with a pair of pliers, to expose a fresh surface.

Boring a hole in glass