AiR-TIGHT STOVES. 45 



products of combtistion imparting it to the interposed hentiug body, 

 from which it is, as before, distributed. 



Ill the case of open fires and FrankUn stoves, the heat, which is ef- 

 fective, is scarcely more than that which is radiated from the burning 

 mass into the room, whilst that portion, which is due to the heated air 

 and gaseous products of the combustion, is carried oft' without produ- 

 cing any useful effect. In this way perhaps nine-tenths of the whole 

 heat evolved is lost. Many indeed are the praises bestowed upon an 

 open blazing fire. There is no doubt something cheerful in being seated 

 by its side, in looking upon the curling flames and the glowing embers, 

 and in receiving the grateful warmth which emanates from them, whilst 

 time is beguiled in conversation with a friend, or the winter evening is 

 spent in the happy family circle. But there is no doubt more poetry 

 and sentimentalism in the idea, than real benet^it derived. It cannot es- 

 cape the most careless observer that there is not much economy, or, in 

 cold weather, much comfort in such a fire ; or that the quantity requisite 

 to produce comfort is enormously great, comiiared with other means of 

 producing the same result. 



In the case of the ordinary close stoves, the eftective heat is much 

 greater than in the case just noticed. Both the radiant heat from the 

 buining mass, and a part of that of the gaseous products are received by 

 the parts of the stove and the pipe which surround them on all sides, 

 and radiated by them to the diflerent objects in the room. Hence the 

 close-stove is a great improvement upon the open fire or the Franklin 

 stove. But even here, a loss of perhaps nearly three-fourths of all the 

 heat generated is sustained, in consequence of the imperfect joinings of 

 the different parts, on account of which, to prevent smoking, a strong 

 draught is always rendered necessary. Through the large opening at 

 the bottom of the front door and the large pipe a strong current is estab- 

 lished, carrying up with it the heated products of combustion, &c., be- 

 fore tliey can impart their caloric to any of the heating surfaces. This 

 is evident to any one who remembers, tliat an upper room is often com- 

 fortably heated by a part of this waste heat by means of a drum. The 

 waste is just in proportion to the strength of the draught. The ten 

 plate stove, ichcn the side doors ichich enclose the ovc7i are kcjii open, is 

 more effective in throwing off heat than the eight plate stove, because 

 then a greater heating surface is exposed. 



It would obviously be a great gain if the heat of the heated air and 

 gaseous products, which is lost in the ordinary stove, could be econo- 

 mized, or made to add its influence to that which is radiated from the 

 fuel. If, for instance, a valve or damper were inserted in the pipe, the 



