ce. Some gave a better light,
but it was objected that they might consume more gas. Whereupon the
chemist tore a strip from his well-worn handkerchief, and, having damped
it, wound the ribbon several times around the top of the old burner
(which had been replaced), leaving the orifice uncovered. The new burner
was screwed down over this, making a gas-tight connection. "There," said
he, "we have a gauge. The new burner will receive the same amount of gas
that the old one consumed--no more, no less--but the current is slightly
checked."

The burner gave the same amount of light as before, so far as the eye
could perceive.

"In the combustion of gas for heating purposes," continued the chemist,
"seek the burner with free, rapid delivery through small holes. For
light you want something different. Suppose you send a current of gas up
into this sewing-thimble: it can find an exit only by turning backward.
Then suppose it escapes from the thimble only to enter a larger cavity
above it, whence it must issue through a burner-tip with an orifice of
the usual size. The current, you perceive, is twice completely broken.
It will be seen that only the expansive force of the gas, together with
its buoyancy, acts upon the jets, instead of a direct current. Now, it
will always be found that the burner which best carries out the
principles just illustrated--other points being equal--will give more
light with a less quantity of gas than any other. This also exhibits
the chief principle of most of the governors or regulators.

"You will observe that this checking of the current is attained in
various ways in different burners," continued the chemist as he
unscrewed and dissected the samples before him. "In some it is done by a
perforated metal disk in the orifice; in others, by a bit of wool, which
checks slightly a slow current, and by the pressure of a strong one
becomes compacted and forms a more effective obstacle. In most cases,
however, it soon becomes solid with condensed matters from the gas.
Another form of check is a small cap having perpendicular slits at the
sides. The cylinder of the cap, being smaller than the orifice of the
burner, screws down into it; the openings being shortened or lengthened
according as the cylinder is screwed up or down. One objection to this
is the trouble required in regulating. Here is another burner, in which
the orifice ends in a cap whose sides, near the bottom, are pierced with
four pin-holes