red to reduce it to a systematic
operation.

A sheet of cardboard, about two feet square, is painted dead black and
suspended horizontally, painted side downwards (Fig. 70, A), at a
height of about two feet above the blow-pipe flame. The latter is
adjusted so as to point almost vertically upwards and towards the
centre of the cardboard. A few half-inch pins are thrust through the
card from the upper surface and pushed home; about one dozen pins
scattered over the surface will be sufficient. Their object is to
prevent the threads being carried away round the edge of the screen.

The flame from the jet described so often is fed from gas bags
weighted to about eighty pounds per square foot of (one) surface,
i.e. "4-foot" bags require from three to four hundredweight to give
an advantageous pressure. [Footnote: The resulting threads were really
too fine for convenient manipulation, so that unless extremely fine
threads are required it will be better to reduce the pressure of the
gases considerably.]

Two sticks of quartz are introduced and caused to meet just in front
of the inner cone--the hottest part of the flame. They are then
drawn apart so as to form a fine neck, which softens and is bent in
the direction of motion of the flame gases. When fusion is complete
the neck separates into two parts, and a thread is drawn from each of
them. By alternately lightly touching the rods together, and drawing
them apart, quite a mass of threads may be obtained in two or three
minutes, when the process should be stopped. If too many threads get
entangled in the pins, one gives one's self the unnecessary trouble of
separating them. On taking down the card it will be found that the
threads have been caught by the pins; but the card now being laid
black side upwards, the former easily slip off the points.

Threads at least a foot long, and perhaps vastly longer, may be
obtained by this method, and are extraordinarily fine. When I first
read Professor Nichols' statement (Electric Power, 1894) as to the
value of these fibres for galvanometer purposes, I was rather
sceptical on the ground that the threads would tend to get annealed by
being drawn gradually, instead of suddenly, from a place of intense
heat to regions of lower temperature.

Now annealing threads by a Bunsen makes them rotten. The threads
being immersed in the hot flame gases could only cool at the same rate
as the gas, and it was not--and is not--clear to