168 HEATING AS APPLIED IN HORTICULTURE. 



either be brought to play upon half 

 of the exterior surface of the boiler, by 

 being made to turn at the throat into a 

 narrow flue which encompasses the boiler; 

 or if the boiler is set on open brickwork, 

 the flame will play round a large portion 

 of its surface, while the bottom, forming 

 the top of the furnace, has the whole force 

 of the fire acting on it. 



Burbidge and Healy's boiler and fur- 

 nace. — Fig. 189 is a section of the boil- 

 er, furnace, 

 Fig. 189. and brick , 



work ; fig. 

 190, plan of 

 the same ; 

 and fig. 192, 

 elevation of 

 boiler, with 

 its ribbed 

 surface. By 

 reference 

 to these 

 figures, it 

 will be seen 

 that the 

 plan of the 

 boilers and 

 containing - 

 furnace is 

 circular — 

 the boiler 

 being com- 

 posed of 

 two trun- 

 cated cones, 

 one inserted 

 ( within the 

 other in 

 such a form 

 as to enable 

 n _H__ the fire to 

 WPact power- 

 fully upon 

 its sides, 

 and to offer 

 a most ex- 

 tensive sur- 

 face to its 



action; the whole surface of the boiler 

 being exposed to the joint action of the 

 fire and heated fluids, as well as a con- 

 siderable portion of the conducting-pipes. 

 It will also be observed that the sides 

 of the boiler are ribbed, which adds 

 greatly to the surface exposed to the fire, 

 and to the strength of the boiler. The set- 



Fig. 191. 



ting of this boiler is simple, and the soot 

 easily removed. In no place is the fuel in 

 contact with the boiler: in every case where 

 it is so, we apprehend great loss of fuel 

 from the rapid abstraction of heat, caus- 

 ing imperfect combustion. This apparatus 

 is greatly improved by having Sylvester's 

 patent fire-doors, which are fitted with 

 great accuracy, admitting of the utmost 

 precision of regulation — a point of the 

 greatest importance in arranging the 

 action of the fire. An evaporating pan 

 forms a cover to the top of the furnace, 

 easily removed and replaced, for the pur- 

 pose of cleaning the boiler. It also acts 

 as a reverberator, and should, under ordi- 

 nary circumstances, be filled with non- 

 conducting materials, such as fine sand ; 

 and in cases where the boiler is fixed inside 

 the house, it may be the means of rapidly 

 saturating the atmosphere with moisture 

 by evaporation. By placing the boiler 

 within the house in a niche in the back 

 wall, and managing the fire from without, 

 a great saving of fuel will be the result. 



Corrugated boilers, such as the above, 

 have been adopted with the view of gain- 

 ing increased heating surface by their 

 projections ; but this application has 

 been found liable to some objection, the 

 draught being sometimes impeded by 

 soot collecting in the interstices between 

 the ribs — although some are cast with 

 external ribs, of a form which obviates 

 this inconvenience. Wrought-iron boilers 

 have been constructed, by the insertion of 

 iron pins into those parts acted on by the 

 heat, and projecting into the furnace and 

 flues, so as to catch the effect of the 

 flame ; but those do not appear to stand 

 high in public estimation. 



We observe an important notice in 

 Messrs Burbidge and Healy's prospectus, 

 namely, that if a correct plan of a house 

 or pit to be heated be forwarded to them, 

 the whole apparatus will be supplied, so 

 that any intelligent labourer and brick- 

 layer can put it together without the aid 

 of any mechanic whatever. 



The following are given by Messrs Bur- 

 bidge and Healy as the powers of their 

 boilers, viz., — 



A 10-inch ribbed boiler will heat from 50 to 

 70 feet of 4-inch pipe, and from 25 to 40 feet 

 in length of a forcing pit. 



A 12-inch boiler from 80 to 125 feet of pipe, 

 and from 40 to 65 feet of pit. 



