By John Rogers, Jim., Esq. 



309 



England ; the only possible exception is in the case of forcing 

 houses for very early grapes, and it is very doubtful whether even 

 here any good would be attained by greater power. I am aware 

 that it is urged that it is always easy to work an apparatus below 

 its power, and that such an arrangement is economical of fuel, and 

 within certain limits this is undoubtedly true ; but if the quantity of 

 pipe materially exceeds what is necessary, the only means of 

 keeping the house at a moderate temperature is by leaving the fur- 

 nace door open, and a very great waste, instead of any economy of 

 fuel, necessarily results. The simplest remedy for this defect is to 

 encase some portion of the pipes either with sand or sawdust, 

 which prevents the heat from escaping into the house by diminish- 

 ing the radiating surface. 



The next point which requires notice is the expediency of heating 

 several houses from the same boiler ; now to this arrangement there 

 is not the slightest objection, provided the same number or extent 

 of houses are always to be heated at the same time, that is to say 

 several hothouses all which require permanent heat but different 

 temperatures may be advantageously heated from one boiler. In 

 like manner a range of greenhouses always requiring heat at the 

 same time, to exclude part, may be worked from one boiler, though 

 different degrees of heat are required in them, and even if one of 

 these sometimes requires, as it probably would, a slight degree of 

 heat when the others need none, this may be arranged without 

 difficulty or inconvenience; but serious inconvenience will arise 

 from any attempt to heat two buildings, in one of which occasional 

 and in the other permanent heat is required, and this inconvenience 

 will be great in proportion to the size of the buildings, especially, 

 if as is generally the case, the hothouse is small and the green- 

 houses or pits more extensive. The same inconvenience will also 

 be felt if two vineries, one to be forced at a later period than the 

 other be heated from one boiler ; the reason is briefly this, that the 

 capacity of the furnace for fuel, the area of its bars or its consuming 



