of a second clip. In
this way we easily get a sort of windlass quite strong enough for our
purpose.

Fig. 35.

Provide a large blow-pipe, such as the blow-pipe of a Fletcher
crucible furnace, Select a length of tubing and clean it. Lash one
end to the cylinder by means of a bit of wire, and hold the other end
out nearly horizontally. Then start the blow-pipe to play on the tube
just where it runs on to the asbestos cylinder, and at first right up
to the lashing. Get an attendant to assist in turning the handle of
the windlass, always keeping his eye on the tube, and never turning so
fast as to tilt the tube upwards. By means of the blow-pipe, which
may be moved round the tubing, heat the latter continuously as it is
drawn through the flame, and lay it on the cylinder in even spirals.

If the tubing is thin, a good deal of care will have to be exercised
in order to prevent a collapse. A better arrangement, which, however,
I have not yet tried, would, I think, be to replace the blow-pipe by
two bats-wing burners, permanently fastened to a stand, one of them
playing its flame downwards on to the top of the flame of the other.
The angle between the directions of the jets might be, say, 130 deg., or
whatever is found convenient. In this way the glass would not be so
likely to get overheated in spots, and better work would doubtless
result. However, I have made numbers of perfectly satisfactory
spirals as described. Three or four turns only make a sufficiently
springy connection for nearly all purposes.

Sec. 37. On Auxiliary Operations on Glass:-

Boring Holes through Glass:- This is much more easily done than is
generally supposed. The best mode of procedure depends on the
circumstances. The following three cases will be considered:-

1. Boring holes up to one-quarter inch diameter through thick glass
(say over one-eighth inch), or rather larger holes through thin glass.

2. Boring holes of any size through thick glass.

3. Boring round holes through ordinary window glass.

Sec. 38. Boring small Holes.

Take a three-cornered file of appropriate dimensions, and snip the
point off by means of a hammer; grind out most of the file marks to
get sharp corners. Dip the file in kerosene, and have plenty of
kerosene at hand in a small pot. Place the broken end of the file
against the glass, and with considerable pressure begin to rotate it
(the file) backwards and forwards with the fingers, very mu