“You will find, if you try, that you can with difficulty push through that hole a hair from your beard.  But, small as it is, it must be perfectly smooth, and of an accurate gauge.  I do not any longer myself set the stones in the brass, as I am not so strong as I once was.  My son does that for me.  But neither he nor my daughter, nor anybody else in this country, I believe, can bore the holes so well as I can even yet.  ’How long does a draw 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