less happen at times, a piece of work gives trouble and
it is necessary to pause and consider the whole question, or if for any
other reason it is necessary to stop during the construction of a
partially finished join or other operation, great care should be taken
not to allow the work to cool. A large, brush-like flame may be produced
by increasing the amount of gas admitted to the blowpipe, and the work
should be held just in front of the current of hot air produced by such
a flame.

It will then be possible to continue work on this without causing it to
crack when further heat is applied.

As time goes on, the student will find an increasing confidence in his
ability to manipulate the soft glass, and with increasing confidence
will come rapidly increasing power of manipulation. Perhaps the greatest
obstacle to success in glass-blowing is undue haste in manipulation.

INDEX

Absorption bulbs, 21, 23.

Airtube, flexible, 8, 102.

Alarm thermometer, 45.

Annealing, 7, 60.

Bellows, adjusting pressure of, 5, 6.

Bellows, foot, 5, 6.

Bending tubes, 23.

Blackening, 58, 101.

Branching, 18, 19.

Brushes of spun glass, 53.

Blowpipe flame, quality of, 3.

Blowpipe for mouth blast, 80, 82, 84.

Blowpipe, for paraffin wax, 82, 88.

Blowpipe, Herepath's, 2.

Blowpipe jet, centring, 3, 98.

Blowpipe jet, dirt in, 3.

Blowpipe jet, multiple, 4, 40.

Blowpipe, Letcher's, change, 4.

Blowpipe, simple form of, 80.

Bulb, medially on tube, 22.

Bulbs, 19, 20, 22, 38, 98.

Bulbs, absorption, (Liebig's), 21, 23.

Bulbs, dividing, 39, 95.

Bulbs from rod, 25.

Bulbs, internal, 38.

Bulbs, thick, 21.

Cages, from glass rod, 24, 25, 27.

Calibration, 72.

Carius tubes, 16.

Condenser, Liebig's, 37.

Condensers, various, 37, 38.

Cone, carbon, 8.

Crack, leading, 30, 99.

Cracking, subversive, 103.

Cutting glass with diamond, 30.

Cutting tubes, 11, 99.

Diamond (glazier's), use of, 30.

Dissimilar glass, joining of, 22, 94.

Drilling, 61.

Electrodes, sealing in, 42, 97.

Etching glass, 70.

Extemporised appliances, 80.

Examination of apparatus, 93.

Failure, Haste chief Source of, 103.

Failures, Notes as to, 97.

File, with oblique ground edge, 7.

Filing glass, 63.

Filter pumps, 35

Foot, 25

Fuels various, 82, 86, 87, 89.

Funnel, thistle, 23.

General principles and precautions, 1, 97

Glass, varieties of, 9, 55, 91-97.

G