How to Cut Glass Disks.
—By sawing out a round board, laying it flat on a sheet of glass and running your glass cutter around the edge of the pattern you can cut out an approximately round disk of glass.
Fig. 86. a circular glass cutter
But to cut out a perfectly round disk you must have a circular glass cutter[98a] as shown in [Fig. 86]. It has an adjustable cutter head mounted on a square rod so that the head can be turned on it. The rod is mounted on a hardwood base so that it can revolve around the latter.
[98a] You can buy one of these tools of Hammacher, Schlemmer and Co., Fourth Ave. and 13th St., New York.
After the cutter head is set on the rod for the size of the circle you intend to cut hold it down on the glass by the thumb-piece. The cutter head is then moved round in a circle and a clean cut is made after which the edge of the disk can be smoothed up.
This circular glass cutter, which is called the Little Beauty, will cut a circle 20 inches in diameter and costs about 50 cents. If you are making a frictional electric machine this is the tool you need to cut the glass plates with.
How to Bend Glass Tubing.
—It is useful to know how to bend a piece of glass tubing, especially if you are interested in chemistry and want to set up some apparatus—in fact you should know how before you ever start to experiment.