ater and will
disfigure the final bulb. This operation of heating, blowing and pushing
together is repeated several times, until the cylinder becomes as long
as can be conveniently handled (about 1-1/4 inches to 1-1/2 inches). If
more glass is needed than is then contained in the cylinder, the latter
may now be heated as a whole, and blown and pushed gently into a shorter
cylinder of a slightly greater diameter, and more glass then added as
before.

When enough glass has been collected for the bulb, it is all well heated
and blown gently a couple of times, pushing the mass together as
required, until a thick bulb like _d_, Fig. 10, is obtained. The tail
must now be removed at the point indicated by the dotted line. To do
this, a very fine flame is directed on the point where the tail joins
the bulb, and the tube well rotated as the glass softens at that point.
When sufficiently soft, the work is raised a little, so that the flame
instead of striking the glass squarely at the point indicated passes
below and tangential to it. The tail is now drawn off slowly, continuing
the rotation, raising the work just out of the flame whenever the thread
of glass drawn off becomes too thin, and lowering it again to the point
where the flame just touches it when the glass stiffens a little. By
this means the tail may be drawn off without leaving an appreciable lump
behind, as indicated in _e_ and _f_, Fig. 10. When as much of the extra
glass has been removed as is practicable, the flame is brought to play
squarely upon the little lump left, the last of the tail removed, and
the lump heated and gently blown to a small excrescence on the main
bulb. The whole end of the latter is now heated until it begins to
shrink a little, and gently blown to make it uniform in thickness. The
whole bulb is then heated in a flame of the proper size, so that it all
may shrink to about two-thirds of its diameter. The flame must be very
carefully chosen and directed, so as to shrink all the bulb, right up to
the main tube, but not soften the latter. As soon as this stage is
reached, the bulb is removed from the flame, continuing the even
rotation, and blown to the desired size, preferably by a series of
gentle puffs following one another at very short intervals. During the
blowing, the main tube is held in a horizontal position, and any
tendency of the bulb to fall out of line is corrected by the rotation.
If the shape of the bulb or its size are not sati