102 PKACTICAL FLORICULTURE. 



first, that it saves twenty-fivo per cent, in fuel ; second, 

 that our firemen say that -the steam boilers require less 

 labor, and, third, that the steam pipes by the use of valves 

 are easier controlled than the hot water pipes. But, 

 above all, is the certainty that, on a large scale at least, 

 heating by steam must be cheaper than by hot water. 

 Leaving out the question of the cost of boilers, which ought 

 to be relatively the same for the amount of work to be 

 done, we find that a one and one-quarter inch pipe, when 

 heated by steam, does almost exactly the same amount of 

 work as a four-inch hot water pipe ; at present prices the 

 one and one-quarter inch steim pipe costs six cents per 

 foot, while the four-inch hot water pipe costs twenty 

 cents. Thus, the piping costs three times more for hot 

 water than for steam, but so far there has been compara- 

 tively little difference in estimates between the two, owing 

 probably to the steam heating of greenhouses being yet 

 in but few hands. From our experience with steam, I 

 believe that whenever greenhouses are erected to the 

 extent of 5,000 square feet of glass surface, steam should 

 be used in preference to hot water ; if for smaller areas, it 

 may be that hot water would be best. As far as the 

 health of plants is concerned, there is nothing to choose; 

 for although a steam pipe at low pressure radiates at from 

 212 and over, and a hot water pipe at about an average of 

 170 degrees, yet at six inches from either pipe the tem- 

 perature is almost identical, radiation is so rapid. Any 

 one doubting this can easily test it by the thermometer. 



