VEGETABLE PLANTS. I I 



at the sides of the trench should be entirely 

 filled with dry forest-leaves or some other good 

 non-conductor. Common 3 by 6 feet sashes 

 are used crosswise of the bed, precisely as on a 

 manure-bed. Perhaps the only part that needs 

 further description is the furnace. Ours have 

 been constructed, in the simplest manner, of 

 common brick, but, of course, fire-brick would 

 be more lasting. The height of the fireplace 

 is two feet, ten inches of this being below the 

 grate-bars for an ash-pit, and fourteen above 

 the grate for fire. The width necessary for the 

 fireplace of a bed of the above size is twelve 

 inches. 



The grate-bars are each cast separately, and 

 are about thirty inches in length, which form 

 the depth of the furnace from front to rear. 

 Eight of these bars are required, each occupy- 

 ing a space of one and a half inches. Imme- 

 diately back of the furnace there should be 

 a rise of six or eight inches, to prevent ashes 

 and cinders from being drawn up into the pipes. 

 The best article for pipes is the common terra- 

 cotta, which is manufactured and used exten- 

 sively as a substitute for brick chimneys in 

 dwellings. We have found it necessary to con- 

 struct the first ten feet of the flue of brick, as 



