and the Economy of Fuel. 33 



This fact, however extraordinary and incredible it 

 may appear, I have proved by the most unexception- 

 able and conclusive experiments. 



Fire-places may be so constructed that the fire may 

 be made to blow itself, or which is the same thing 

 to cause a current of air to flow into the fire ; and this 

 is an object to which the greatest attention ought to 

 be paid in the construction of all fire-places where it is 

 not intended to make use of an artificial blast from 

 bellows for blowing the fire. Furnaces constructed 

 upon this principle have been called air-furnaces ; but 

 every fire-place, and particularly every closed fire-place, 

 ought to be an air-furnace, and that even were it in- 

 tended to serve only for the smallest saucepan, other- 

 wise it cannot be perfect. 



An Argand's lamp is a fire-place upon this construc- 

 tion ; for the glass tube which surrounds the wick (and 

 which distinguishes this lamp from all others) serves 

 merely as a blower. The circular form of the wick is 

 not essential ; for by applying a flatted glass tube as a 

 blower to a lamp with a flat or riband wick, it may be 

 made to give as much light as an Argand's lamp, or at 

 least quite as much in proportion to the size of the 

 wick, and to the quantity of oil consumed, as I have 

 found by actual experiment. 



But it is not the light alone that is increased in con- 

 sequence of the application of these blowers : the heat 

 also is rendered much more intense ; and as the heat 

 of any fire may be increased by a similar contrivance, 

 on that account it is that I have had recourse to these 

 lamps to assist me in explaining the subject under con- 

 sideration. In these lamps the fire-place is closed on 

 all sides, and the current of air which feeds the fire 



