To drill a hole through a sheet of glass make a layer of putty 1/2 an inch thick and as large as the sheet you are going to drill and lay the glass on it.

The idea of using the bed of putty is to allow the glass to bend a little should you press down on the drill too hard. Take a Morse twist drill and, if you know how, grind it on a grindstone to a sharper point than it has when you get it; the next best thing to do is to sharpen it on your oilstone.

The best kind of a drill stock to use is an archimed-ian, or a reciprocating one, as shown at B in Fig. II, on page 29, for then the pressure on the glass is even in every direction. Set the drill on the glass at the point where the hole is to be made; hold it with the fingers of your left hand to keep it from slipping and lubricate it well with turpentine.

Work the drill at a fairly high speed and do not put too much pressure on the drill stock or you will surely break the glass.

You will find it quite hard to drill a hole less than 1/16 inch in diameter through ordinary glass because the drills will break and when you drill a hole over 1/8 inch in diameter you will find it a slow job because of its size, but you can drill a hole up to 1/4 inch in diameter if you go slow and are careful.