HOTHOUSE FURNACES. 



257 



which escapes by the chimney. The 

 restoration of the current of air causes the 

 smoke to cease and the flame to reappear. 



In these essentials the smoke-consum- 

 ing furnaces differ widely from those in 

 common use, because, in the latter, no 

 air can possibly reach the back part of 

 the furnace at the bridge, but is admitted 

 at the front of the fire close by the door, 

 and, in consequence, passing rapidly over 

 the fire, enters the throat of the furnace at 

 the bridge in an improperly heated form, 

 and not only carries along with it a large 

 quantity of smoke, but also a great portion 

 of cold air, which, instead of heating the 

 flues, tends rather to reduce their tempera- 

 ture. In regard to that part of the furnace 

 called the bridge, Mr Ainger, in "Gar- 

 deners' Chronicle," makes the following 

 remarks: — "In ordinary boiler-setting, 

 what is called the bridge, which is in- 

 tended to direct the rising flame and 

 gases into close contact with the boiler, 

 but which, at the same time, shuts out a 

 large space from its radiation, is, I be- 

 lieve, a totally injurious contrivance. By 

 diminishing the primary radiation of the 

 boiler, we, of necessity, give a larger por- 

 tion of heat to the gases which it is suffi- 

 ciently difficult to reclaim during their 

 rapid passage through the thereby over- 

 heated flues, and which escape with an 

 unnecessary large share of heat into the 

 chimney." 



Our own opinion of the exclusion or 

 admission of atmospheric air is, that a 

 very limited quantity is all that is neces- 

 sary, both for the support of combustion 

 and also for the consumption of smoke ; 

 but that this air, whatever its amount 

 may be, should be directed to the warm- 

 est part of the furnace ; — and the warmer 

 it is before it is so applied, the better. Air- 

 tight furnaces should be first constructed ; 

 and, if provided with proper registers in 

 their frames and ash-pit doors, the neces- 

 sary quantity of air can be most readily 

 supplied. 



Fig. 343 is a longitudinal section of a 

 smoke - consuming furnace upon Mr 

 J oseph Williams' principle, and approved 

 of by the Committee of the Health of 

 Towns, &c. The cross section is the 

 same as that formerly given in fig. 90. 

 The furnace door and ash-pit are upon 

 the same principle as those there detailed, 

 as is also the fire-clay grate with its per- 



VOL. I. 



tile 



forations. The leading feature in this fur- 

 nace is the perforated fire-clay tile a, 



placed in 



^ Fig. 343. the throat 



^fe, of the fur- 



nace, and 

 sunk 3 

 inches in- 

 to the 

 groove in 

 the tile d 

 at the 

 back of 

 the grate, 

 and also 

 into the 



e in the evolving-chamber /• Air 

 is admitted, after passing through the 

 ash-pit to become heated, by the aperture 

 b, so as to act with force on the half- 

 inflamed gases and smoke after passing 

 through the perforations in the tile a; for 

 on the quantity and force of this body of 

 air, consumption of the smoke depends. 

 c is a boiler over the fire, but it has no 

 direct connection with the principle of 

 this furnace. 



JucJce's patent smoke-consuming furnace is 

 a very ingenious piece of mechanism, but 

 by far too complicated to be used for 

 ordinary purposes. A set of drawings of 

 it in detail, with description, will be 

 found in the Repertory of Patent Inventions. 



A patent has recently been taken out 

 by Mr G. Ansty of Brighton, which we 

 think worth the attention of furnace- 

 builders. The principles, so far as pub- 

 lished, are in the right direction. His 

 method for more effectually securing the 

 combustion of the smoke is by causing 

 the products of combustion to pass 

 through apertures in plates and cones, 

 and thereby to be retained longer than 

 usual in contact with the flues and heat. 

 And his invention also embraces the 

 means of regulating draught in chimneys, 

 so as to maintain an equable degree of tem- 

 perature at the upper end of the chimney, 

 by preventing any sudden influx of cold air. 



Messrs W. and J. Galloway's patent 

 boilers. — These boilers consist of a cylin- 

 drical shell or outer case containing two 

 cylindrical tubes forming the furnaces. 

 These two tubes unite behind the fire-bars 

 in a single chamber, and it is in this 

 union that their virtue as smoke-con- 

 sumers consists. The ordinary double- 



2 K 



