OLASS STRUCTURES 99 



the crops grow. Ten-inch terra cotta or glazed drain tile 

 is a cheap material for the flue, or brick may be used for this 

 purpose. The furnace and the first eight or ten feet of the 

 flue should be made of common hard brick and have a lining 

 of fire brick set in fire clay. 



If the pit is not over thirty feet long the fire box should 

 be at one end and the chimney at the other; but if much 

 longer it is better to have the chimney over the fire box and 

 to run the tile to the end of the house and return back to the 

 chimney. This chimney should have dampers so arranged 

 that when kindling the fire a direct draft may be had into 

 it, and after starting the 

 fire the heat and smoke 

 can then be forced to go 

 through the whole length 

 of the pipe. This ar- 

 rangement is desirable 

 on account of the diffi- 

 culty in getting a draft 

 through a long, flat, cold 

 flue. In laying such a flue, it should rise slightly through- 

 out its whole length from fire box to chimney. 



The furnace should vary in size according to whether 

 coal or wood is to be used for fuel. For wood the furnace 

 should be 18 inches wide and be arched over the required 

 length, generally 4J/2 feet, with cast-iron grate bars set in 

 the walls. There should be an ash pit of suitable size, and 

 both it and the fire box should have suitable iron doors set 

 in brick. The accompanying illustrations show the general 

 arrangement of such a house. It is a good plan to build a 

 low shed for fuel on the end where the furnace is located. 



The heat from a flue is very dry, and much more water 



