208 FIXED STRUCTURES FOR GROWING 



breadth ; and the coals which are placed on this blank part of the furnace, 

 in consequence of receiving no air from below will burn very slowly, and 

 will only enter into complete combustion when the coal which lies directly 

 on the bars has burnt away." (p. 80.) 



504. Rogers s Conical Boiler and Hot-water Apparatus is believed to be 

 the most perfect and generally applicable in the case of houses of moderate 

 dimensions that has yet been invented, and as such we shall describe it 

 somewhat in detail. It is the result of a series of experiments made by 

 John Rogers, jun. Esq., F.R.S., &c., with the assistance of Mr. Shewin, iron- 

 monger, Sevenoaks, Kent, who manufactures the apparatus for sale. The 

 boiler was originally formed of tinned iron, afterwards of copper, and lastly 

 it was cast in iron in one piece. 



Fig. 147 is a front view of the boiler as at present constructed in cast-iron. 

 The interior, a sugarloaf-shaped cone (indi- 

 cated by the dotted lines), being the furnace, 

 which is filled with fuel through its upper 

 orifice, a. A circular fire-grate is fixed just 

 within the bottom of the boiler ; and the 

 aperture &, seen in front, is intended solely 

 to remove clinkers which may form, or fuel 

 when the fire is extinguished ; at other times 

 it is closed with a fire-brick plug, and should 

 never be opened except when absolutely ne- 

 cessary. For a side view of the boiler see 

 fig. 150, where it is represented as attached 

 to a range of pipe ; / and r are the flow and 

 return pipes, and d a flange for examining 

 and cleaning the boiler when necessary. 

 Into this flange is fixed a small pipe, which, 

 being connected upwards with the supply 

 cistern e, and downwards with the cock or 

 tap A, serves to fill and empty the apparatus. 

 The supply cistern e acts also as an expansion cistern, to receive the volume 

 of water increased by heat. 



Fig. 148 shows the most convenient mode of setting the above, exhibited by 



r- 



Fig. 147. Rogers'* conical boile 



Fig. 148. Mode of setting Rogers'* conical toiler. 



a front view. A solid base being built with an aperture in its centre open to 



