Trippel.] "lA [February. 



in the combustion flue, K. The latter has a width of 4' 2", with a 

 mean height of 1' 21", consequently a cross section of 5.3 square 

 feet, with a length of 4' 8". In commencing operations with the 

 furnace, the hot-air valve is closed, the gases pass unburned through 

 the hearth, escaping through all apertures with the blue flame of 

 carbonic oxide gas. Subsequently the air is admitted by degrees, 

 until the flames disappear, and the burnt gases, passing over the 

 hearth, appear clear, bright, and transparent. To avoid oxidation, a 

 little excess of gas is admitted. 



The furnace, L, has a length of 12', a width of 5', and a mean 

 height from hearth to arch of 1' 11". The hearth is seen in plate 

 I, Figs. 1 and 2, and is built in the usual manner, but may be made 

 as judged best by the constructor. The walls and casing are seen in 

 plate /, IV. The arch has a spring of 4 inches. 



The boiler is placed above the furnace, as in most cases, and 

 rests, together with the walls, etc., upon six large iron columns with 

 their frames, and upon two supports in the centre. The products of 

 combustion enter from the flue beneath the boiler, and pass all around 

 the hot-air pipes ; the boiler is provided with a flue, and offers a 

 total heating surface of 263 square feet, equivalent to at least 22 

 horse power. 



In the several plans, we see the arrangement to support the boiler 

 wall are rails and cast-iron plates. The clear opening of the flue 

 leading to the chimney is here only one square foot, in order to com- 

 press the gases in the combustion canal, K, but room is left to in- 

 crease the same, if found necessary, to two or three square feet. 



Calculation for the Furnace. The former consumption of an- 

 thracite for the furnace is presumed to have been 10.2 tons for 24 

 hours, or 952 lbs. per hour. 



In admitting the most advantageous mode of heating with fan 

 blast in the usual way, and estimating the temperature in the fur- 

 nace to 2912° Fahrenheit, as the extreme, we have as useful efi'ect: 



4161° initial temp, of anthracite. 

 Minus 2912° temp, of furnace. 



1249° divided by 2912°— 0.30 =30 per cent. 



The same fuel gives with gas-heating, 



4928°-2912° 



jq^q = 0.409, or 40 per cent. 



We can consequently diminish the fuel at the ratio of 40.9:30 = 

 10.2 tons: ;f = 7.4 tons, or 27.4 per cent, saving in fuel. 



