Heating Grccn-hoiiscs. 9 



and throughout the long nights they are a minus quantity. We may 

 get some help from the heat of fermentation ; yet its power is so lim- 

 ited, and its expense is so greatly above that of fire heat, that " hot- 

 beds " will, in the future, be more and more strictly confined to small 

 efforts and special purposes. At present we are almost limited to the 

 heat of combustion for the purpose of keeping up a night temperature 

 for plants during winter. It is a most important question how we can 

 best apply our fire heat. 



We place a lamp in the green-house, and a considerable amount of 

 heat is given off, the total of which is retained, absolutely none going 

 off in a smoke flue. This is perfect economy of heat. But the small 

 amount of smoke and gas from the lamp is injurious ; and when we 

 use other materials, such as wood or coal, as a fuel, the case becomes 

 much worse. We are compelled to provide an escape for the smoke 

 and gas. Hence we build furnaces and chimneys. But the chimneys, 

 if they run up perpendicularly, carry oft' a large percentage of the heat. 

 In order, therefore, that more and better radiating surfoce may be ob- 

 tained, as well as for more equal distribution of'heat. we run horizontal 

 flues once or twice the length of the house. This is a gain in both di- 

 rections ; yet it is very far from perfection. It also wastes a large per- 

 centage of heat, and what it docs radiate is mainly at the fire end of 

 the house. To remedy the last objection was suggested the Polinaise 

 system of leading a column of air from the cold end of the house, 

 through a subterranean drain, under and around the furnace, and out 

 into the house — a simple and a wise plan of putting the air of the 

 house in circulation, leading it from the cold end up to the fire to be 

 warmed, and then to flow back leisurely to fill up the vacuum. It is a 

 modification of the hot-air furnace system, by which a majority of our 

 dwellings are now heated. But still the apparatus is very imperfect, 

 especially as ordinarily constructed. Not to dwell upon the evil of the 

 flow of the hot air to the top of the house, let us consider the heavy 

 stack of brick around the furnace, and the usual heavy flue and chim- 

 ney. Through such a thick covering the caloric is not freely radiated, 

 and consequently it is, to a very serious extent, retained, and communi- 

 cated to the smoke column passing up the chimney. In other words, 

 the heat is smothered under a mass of brick, and finds an escape 

 through the flue. 



Now the water S3'stem comes in, to our great relief. It is a perfect 

 relief on the point of distribution of heat ; a^pd in respect to economy 

 of fuel it has been a help, for the water in the boiler absorbs the caloric 



