concern. It will, perhaps, be new to many of you that blowpipes can easily
be made in a form which admits of any special shape of flame being
produced. I have made for special work--such as heating up odd shapes of
forgings, brands, etc.--blowpipes constructed of perforated tubes formed
to almost every conceivable shape; these being supplied with gas from the
ordinary main and a blast of air from a Root's or foot blower. I have here
an example of a straight-line blowpipe made for heating wire passed along
it at a high speed. The same flame, as you no doubt will readily
understand, can be made of any power and of any shape, and will work any
side up; in fact, as a rule, a downward vertical or nearly vertical
position is usually the best for any blowpipe. As an example of this class
of work, I may instance the shrinking on of collars and tires, which, with
suitable ring-burner and a Root's blower, could be equally heated in five
minutes for shrinking on; in fact, the work could be done in less time
than it would usually take to find a laborer to light a fire. When the
rings vary much in size, the burners can easily be made in segments of
circles. But then they are not nearly so handy, as each needs to be
connected up to the gas and air supply; and it is, in practice, usually
cheaper to have separate ring burners of different sizes. Of course, you
will understand that a ½-inch gas-pipe will not supply heat enough to make
a locomotive tire red hot, and that for large work a large gas supply is
necessary. Our own rule for burners of this class is that the holes in the
tube should be 1/8 to 1/10 inch in diameter, from ¼ to ½ inch pitch; and
the area of the tube must be equal to the combined area of the holes. The
gas supply-pipe must not be less than half the area of the burner-tube.
Those of you who wish to study this matter further will, I think, find
sufficient information in my paper on "The Construction of High-Power
Burners for Heating by Gas," printed in the Transactions of the Gas
Institute for 1883, and in the papers on the "Use and Construction of the
Blowpipe" and "The Use of Gas as a Workshop Tool."