2 3 2 THE POPULAR SCIENCE MONTHLY. 



brickwork, and so into the chimney. The greatest offenders are the 

 ordinary register grates. Iron all over, back, and sides, and roof, they 

 are usually set in a chamber open above to the chimney, and imper- 

 fectly filled in, or not filled in at all, with brickwork. The heat es- 

 capes through the iron to this chamber, and thence is lost. Another 

 fault is that the " register-opening," in other words the " throat of the 

 chimney," being immediately above the coal, submits the burning fuel 

 to the full concentrated force of the current to the chimney, convert- 

 ing the fire into a miniature blast-furnace. On this point Rum ford 

 says : " But there are, I am told, persons in this country who are so 

 fond of seeing what is called a great roaring fire, that even with its 

 attendant inconveniences, of roasting and freezing opposite sides of 

 the body at the same time, they prefer it to the genial and equable 

 warmth which a smaller fire, properly managed, may be made to pro- 

 duce, even in an open-chimney fireplace." 



The second result of faulty construction in fireplaces is "undue 

 production of smoke and soot." Smoke and soot imply imperfect 

 combustion, and to this two defects in a fire mainly contribute, one, 

 too rapid a draught through the fire which hurries away and chills 

 below burning-point the gas rising from the heated fuel. The other 

 defect is too cold a fire, i. e., too small a body of heat in and around 

 the fuel, so that the temperature of the gases is not raised to a point 

 at which they will burn. On the smoke question Rumford waxes 

 eloquent : " The enormous waste of fuel in London may be estimated 

 by the vast dark cloud which continually hangs over this great me- 

 tropolis, and frequently overshadows the whole country, far and wide ; 

 for this dense cloud is certainly composed almost entirely of uncon- 

 sumed coal, which, having stolen wings from the innumerable fires of 

 this great city, has escaped by the chimneys, and continues to sail 

 about in the air till, having lost the heat which gave it volatility, it 

 falls in a dry shower of extremely fine black dust to the ground, ob- 

 scuring the atmosphere in its descent, and frequently changing the 

 brightest day into more than Egyptian darkness." 



A few years ago the prevalence of unusually dense fogs roused the 

 metropolitan public to a sense of this great evil. The Smoke Abate- 

 ment Society was formed, and under its auspices exhibitions of smoke- 

 consuming apparatus and improved fireplaces were held in London and 

 Manchester. Beyond the fact that certain grates were pronounced to 

 be good in point of economy, and moderate in the production of smoke, 

 and that the public has been led to take an interest in and inquire into 

 the relative value and economy of various patent fireplaces, there has 

 been but little advance in the education of the public in the principles 

 which lie at the root of the whole question. 



A third result of bad construction is the " production of cinders." 

 With good coal, cinders are inexcusable. They are unconsumed car- 

 bon coke and imply a faulty fireplace. If thrown into the ash-pit, 



