HEATING GREENHOUSES. 191 



can a large space be heated either by hot water or steam. This 

 point is worthy of close study and careful consideration, for the 

 end to be attained by the horticulturist is the successful growing of 

 plants, and to do this properly, in our cold winter climate, heat in 

 requisite amount must be supplied all over the greenhouse, to pro- 

 duce the teuiperature required for the crop ; and the onl}- way to 

 have at command proper temperature is to be able to heat the 

 water in the boiler quickly. 



Now, -it seems to me that, for a successful heating apparatus, the 

 water must be presented to the fire in such small, continuous 

 divisions that it will become hot in the shortest space of time pos- 

 sible ; therefore I would have m^^ boiler constructed of tubes, 

 and placed over the fire in such a manner that the greatest possible 

 surface of pipe will be exposed to the heat before the heat shall 

 pass off up the chimnej' and be lost. The construction can be 

 ver}' simple, and not expensive. For example : A bank of 1 ^-inch 

 pipe, occupying a space 5 feet long, 2 feet high, and 2 feet wide, 

 bridged in the middle b}' tiles, so that the heat from the fire built 

 under one end shall pass through the bank twice before reaching 

 the chimne}'. Let the bank of pipe be enclosed in brickwork, the 

 top of this brickwork resting on gas-pipe bearings. The whole 

 structure shouhl project into the greenhouse, thereb}' saving all 

 the heat radiated from the furnace. The feed door should be out- 

 side, to prevent coal gas from entering the greenhouse while 

 stoking. This plan will make a fire-box 2 feet wide by 2 feet 

 long, which would be sufficient for heating two greenhouses 100 

 feet long by 20 feet wide. The water is to pass in at the bottom 

 of the bank of pipe, and out at the top, thus being in oyie continu- 

 ous small stream of 100 feet long through the bank of jDipes. 



The flow of water in one stream through such a length of pipe 

 (one hundred feet), and over a live fire, ought to heat the water 

 very hot in a short space of time, there!)}' making it flow through 

 the radiating pipes with such velocity as to cause its rapid return 

 to the boiler after giving off its heat as required. This is the 

 great secret of successful heating, and I ask for it your most care- 

 ful consideration, for, with a higher initial temperature and rapid 

 circulation, we shall not require such large radiating pipes as four 

 inches to heat our greenhouses, nor so manj- of them ; for what we 

 require to properly do the work will be kept very hot, even in the 

 return section, by the constant and rapid passing of the current 

 through the fire in one continuous small stream. 



