INTRODUCTION. V 



dark lantern with a front and a back glass O G, suspended 

 by cross-strips within a well-ventilated protecting shell, 

 where it can do most good with its light, and the least 

 harm with its heat. Other parts of the apparatus are ad 

 justed with ease and precision to this fixed centre of action, 

 by means of the outer shell and wooden base, which are 

 represented in the above illustration as mostly cut away to 

 show these internal arrangements. Thus, by allowing un- 

 obstructed draft about the heated chamber, and by avoid- 

 ing the conduction of heat by contact, the intense Sciopti- 

 con flames become available without inconvenience to the 

 operator, or harm to adjacent parts. 



2. The Lamp (/S), without deflecting cap or chimney, 

 slides horizontally into place, so that the bottom of the 

 flame chamber, with its peculiar-shaped aperture, becomes 

 the deflecting cap, the flame chamber becomes the base of 

 the chimney, and, with its continuation, is the chimney; 

 which happily supersedes the troublesome and fragile small 

 chimney, being much more than an equivalent. Be- 

 sides being thus separate from the heated chamber, direct 

 conduction of heat to the oil cup is further broken by 

 breaking the connection on each side of each tube, as at u. 

 The material is tin instead of brass, because it is not so free 

 a conductor of heat. 



3. Two Flames, starting wide apart at v v, are deflected 

 toward each other over a rising current of air which thor- 

 oughly oxygenates the inner surfaces, their cumulative heat 

 favoring perfect combustion, a free draft, and the rapid 

 escape of the residual gases up the narrow space between. 



Other dual burners (not infringements on this) either 

 throw the two flames into one and into only the efficiency 

 of one, because only the outer surfaces are oxygenated or 



