HEATING GREENHOUSES. 195 



In this wa}' he gets nearly all the good of his fire in heating water 

 in the boiler or jacket. His copper boiler is 2^ feet high b}' 16 or 

 18 inches diameter, and he heats a house 180 feet long by 15 feet 

 wide with five 2-inch pipes. 



This idea of heating water under pressure was first brought to 

 my attention by Mr. Denys Zirngiebel, who has it in successful 

 operation at his place in Needham. And now I learn that Mr. A. 

 P. Calder has adopted the same plan, and, if he is present, will tell 

 us of his success. Before I put any thought into this subject I 

 never supposed that water could be heated much hotter than the 

 steam point ; and it cannot if it is not confined ; but when you once 

 confine it and apply heat you can bring it to almost any high tem- 

 perature 3'ou desire, therefore 3-ou will readily see that large spaces 

 can be heated more quickly' when pressure is used. I know of a 

 great number of greenhouse men, who are warming their houses by 

 trying to heat from twelve hundred to fifteen hundred gallons of water 

 with a jacket boiler surrounding a fire, but with the boiler exposed 

 to the damp air of the stoking-pit. In some instances they begin 

 an intense fire at noon, and keep it up till ten o'clock at night, 

 melting the coal into clinkers, wasting great quantities of heat and 

 causing great anxiety. A gentle continuous fire under my boiler 

 will keep the water always hot, and can be kept in the proper con- 

 dition, when a cold night overtakes one, to immediately respond to 

 a good stoking, and carry the temperature to a point to allay all 

 anxiety, so that one can rest in peace. 



Heating greenhouses is very similar to heating dwelling-houses.- 

 Some people think that ii the cold air box is wide open a great 

 amount of heat is sure to enter the rooms, whereas the opposite is 

 the result; and the inmates of those houses are cold, and often re- 

 mark that the furnace is not a good one. Now, if some one would 

 kindl3- close the air-box down to a space six inches square, all the 

 air coming through such a space would be warmed, and the furnace 

 pronounced a good one. Just the same experience happens with 

 radiating pipes in the greenhouse ; two-inch pipes can be kept very 

 hot with an ordinary fire, such as would only just warm four-inch 

 pipes ; therefore I would caution horticulturists not to put in more 

 pipes than they can properly heat ver}" hot, for when we get more 

 than can be so heated we are throwing away fuel, and jeopardizing 

 our plants. 



