By John Rogers, Jun., Esq. 



307 



The real desideratum is a furnace so constructed that it shall con- 

 tain fuel enough to supply the pipes with as much heat as they can 

 radiate during the night, and which may he depended upon for 

 burning steadily and perfectly whatever fuel is put into it. Not 

 with that accurate precision requisite where the temperature of the 

 house depends upon the exact amount of combustion per hour, but 

 sufficiently slowly to allow the water to absorb the greatest possible 

 portion of the heat generated. With such an apparatus, the fire 

 being once effectually lighted, the gardener need be under no appre- 

 hension that the heat during the night will prove insufficient, though 

 it may be several hours before the pipes attain their maximum 

 temperature. 



I have dwelt somewhat at large on this point because it is one on 

 which much mistake exists, and under this misapprehension, the best 

 apparatus may be condemned as defective, and a very imperfect 

 one preferred and adopted in its stead — that which is commonly 

 adopted as a criterion of excellence, being really a proof of de- 

 fective construction. 



There can be on the whole no doubt that three inch or four inch 

 pipes are exceedingly preferable to smaller ones, where economy of 

 fuel and uniform adjustment of the temperature for several hours, 

 are the primary objects; where ornament or great economy of 

 space is important, and economy of fuel is not much considered 

 smaller pipes may be employed ; but where rapid heating is con- 

 sidered essential, I believe it will be found best to have recourse to 

 the old expedient of brick flues ; and their attendant inconveniences 

 must be considered as the price paid for this advantage real or 

 imaginary. The most perfect construction of these has been so fully 

 canvassed in the earlier volumes of the Horticultural Transactions 

 that it is unnecessary here to enlarge upon it. 



The next point to be noticed is the absolute amount of heat 

 produced by any hot water apparatus, which depends upon the 

 proportion between the surface of pipe and surface of external glass 



