and the Economy of Fuel. 85 



the fire is let in under the grate through a register in 

 the ash-pit door. 



When the double doors which close the entrance 

 into the fire-place are shut, the flame of the burning 

 fuel first rises perpendicularly against the bottom of the 

 boiler ; it then passes along to the farther end of the 

 (middle) flue, which constitutes the fire-place, where it 

 separates, and returns in the two side flues ; it then 

 rises up into two horizontal flues (one situated over the 

 other) which go all round the boiler ; and, having made 

 the circuit of the boiler, it goes off into separate canals 

 (furnished with dampers) into the chimney. 



Though the Figures 17 and 18, Plate III., are not 

 drawings from the fire-place I am now describing, but 

 of another which I shall soon have occasion to describe, 

 yet an inspection of these figures will be found useful 

 in forming an idea of the principles on which the fire- 

 place in question was constructed, and on that account 

 I shall occasionally refer to them. 



The burning fuel being confined within a narrow 

 compass, being well supplied with fresh air, and 

 being surrounded on all sides by thin walls of brick 

 (which are non-conductors), the heat of the fire is most 

 intense, and the combustion of the fuel of course very 

 complete. The flame, which is clear and vivid in the 

 highest degree, and perfectly unmixed with smoke, runs 

 rapidly along the bottom of the boiler (which forms the 

 top of the flues), and from the resistance it meets with 

 in its passage, from friction, and from the number of 

 turns it is obliged to make, it is thrown into innumer- 

 able eddies and whirlpools, and really affords a most 

 entertaining spectacle. 



That I might be able to enjoy at my ease this amus- 



