plate last?' Ah! Practically forever. Except by clumsy handling or
accident, it does not need to be replaced, at least in one lifetime. And
there is another reason why I sell so few now. Those who require them are
supplied. 'Watch jewels?' Yes, I used to make them, but do so no longer.
They can be imported from Europe at the price of $1 a dozen, and at such a
figure one could not earn bread in making them here."--_Manuf. Gazette._

* * * * *

BAYLE'S LAMP CHIMNEY.

The different types of lamps used in domestic lighting present several
imperfections, and daily experience shows too often how difficult it is,
even with the most careful and best studied models, to have a perfect
combustion of the usual liquids--oil, kerosene, etc.

[Illustration: BAYLE'S NEW LAMP CHIMNEY.]

Mr. P. Bayle has endeavored to remedy this state of things by experiments
upon the chimney, inasmuch as he could not think of modifying the
arrangements of the lamps of commerce "without injury to man" interests,
and encountering material difficulties.

The chimney is not only an apparatus designed to carry off the smoke and
gases due to combustion, for its principal role is to break the
equilibrium of the atmospheric air, which is the great reservoir of
oxygen, and to suck into the flame, through the difference of densities,
this indispensable agent to combustion. The lamps which we now use are
provided with cylindrical chimneys either with or without a shoulder at
the base. The shouldered chimney would be sufficient to suck in the
quantity of air necessary for a good combustion if we could at will
increase its dimensions in the direction of the diameter or height. But,
on account of the fragile nature of the material of which it consists, as
also because of the arrangement of the lighting apparatus, we are forced
lo give the chimney limited dimensions. The result is an insufficient
draught, and consequently an imperfect combustion. It became a question,
then, of finding a chimney which, with small dimensions, should have great
suctional power. Mr. Bayle has taken advantage of the properties of
convergent-divergent ajutages, and of the discovery of Mr. Romilly that a
current of gas directed into the axis and toward the small base of a
truncated cone, at a definite distance therefrom, has the property of
drawing along with it a quantity of air nearly double that which this same
current could carry along if it