88 PROCEEDIXGS OF THE CANADIAN INSTITUTE. 



all gases — and this heat radiation is what we desii-e to utilize com- 

 mercially — is increased proportionately to its absorbent power; there- 

 fore, to take all possible calorific value from the escaping gases, they 

 are after leaving the boiler flues, moistened down to dew point by 

 hot water-spray through a rose-jet, and also by admixture with the 

 exhaust steam from the fan-engine, and then passed over a sufficient 

 number of coils of metal pipe (heat absorbents) through which the 

 feed water is moving on its way to the boiler. 



It is claimed that the products of combustion, when thus satu- 

 rated, part with their heat so completely that a portion of the feed 

 water is converted into steam. 



Mr. Mallett claims that he has arranged his system to meet loco- 

 motive requirements, the exhaust steam from the main cylinders, 

 instead of educing blast, being used partially to warm fresh air for 

 coach ventilation, and partially condensed in the tender tank, thus 

 warming the feed water. We regret that experimental results can- 

 not be given showing the practical value of this novel attempt at 

 economical and smokeless combustion of soft coal. 



3rd. HowDEN. — His method, as illustrated in a boiler of the single 

 return-flue type, has the back head-sheet boxed up, forming a reser- 

 voir, through which all the air required is forced (under compression) 

 by a fan, and it is warmed in its course past the head-sheet and 

 around the smoke-flues that traverse this chamber from smoke-box 

 to chimney. From this chamber the air exit is by passages leading 

 both to the upper part of the furnace and to the ash-pit, with their 

 actual amount of opening controlled and con.stantlv varied by the 

 stoker, through the movement of levers on the outside, thus giving 

 him the independent control of the amount of compressed air sup- 

 plied, either above the solid fuel or below it ; air-tight doors prevent- 

 ing any escape from the inside except by way of the chimney, which 

 need be but of short length. 



Opening the furnace door to admit fresh coal automatically closes all 

 these plenum air passages, thus preventing the excessive inflow of 

 cold air, so destructive to seams and joints, when (as in those other- 

 wise most successful crafts, the British torpedo boats,) there is air 

 pressure in the closed boiler room. It may be well here to remark 

 that all attempts at forced combustion are with the object of burning 



