A DETACHED GREENHOUSE OK GEAPEET. 93 



which, if kept painted, will last for 50 years, and is 

 equally warm as a 12-inch brick wall, and costs less than 

 half. We have had just such a structure in use for the 

 past five years as a cold vinery, that is having no heating 

 apparatus, the forwarding being done only by the action 

 of the sun on the glass, and it has proved a cheap and 

 satisfactory luxury. A conservatory or grapery of this 

 style costs from $10 to $15 per running foot, without 

 heating apparatus. Heated by hot water, it would cost 

 $20 to $30 per running foot. If heated by a horizontal flue 

 in the manner here described, the cost will be only about 

 $15 per running foot. Any good bricklayer should be able 

 to build a smoke-flue from the following instructions. Let 

 the bars for the grate be, (if for a glass surface of say 500 

 square feet), 2 feet in length and about 10 inches in 

 width ; or in the proportion of about one-half a square 

 inch of grate surface to one square foot of glass. 



Most masons of any experience know how to build a 

 greenhouse flue, but there are a few important points, the 

 knowledge of which is absolutely necessary to complete 

 success. First, the furnace pit, if not naturally dry, 

 must be made so by draining. After setting the grate- 

 bars in the usual way by resting them on an iron plate, 

 let into the brick work at front and back, the sides of 

 the furnace should be built with fire-brick and fire clay 

 if at all procurable, to the hight of from 10 to 20 inches, 

 according to size wanted. On these walls an arch is 

 turned over to cover the furnace; the "neck" of the 

 furnace rising at a sharp angle for from 2 to 4 feet until 

 it is run into the horizontal smoke-flue. The flue must 

 be raised from the ground an inch or two on bricks or 

 flagging. This costs perhaps a third more in building, 

 but it allows all sides of the flue to give off heat. The 

 cheapest and simplest form of flue is made after the bot- 

 tom is formed by bricks or flagging ; brick is best near 

 the furnace, as flagging would crack. Place two bricks 



