420 FORCING DEPARTMENT. 



HOT WALL. 



The accompanying Plate, No. 26, represents the 

 Ground Plan of a wall, heated by Hot- water ; the 

 pipes are introduced along a cavity, that commences 

 within a few inches of the bottom of the wall, and is 

 continued to the top, but is connected by piers, that 

 are carried up about four feet apart, which unite 

 the back and front of the wall together, and render 

 it, although hollow, equal to a solid one in strength ; 

 they are also found more economical in erection, as 

 there is a considerable saving of materials. 



In this structure, the boiler is also placed in the 

 shed behind, where the fire is attended to, and the 

 two pipes proceed one directly under the other, 

 along the cavity to the extremity of the wall, where 

 they are connected to an oblong square box, into 

 which the water flows from the upper pipe, and 

 returns to the boiler by the under one ; and whilst 

 any heat is continued in the furnace, the water will 

 flow and circulate from one extremity of the wall to 

 the other. The caloric given out from the pipes, 

 produces a gentle heat in the brick wall against 

 which the trees are planted, and the warmth given 

 out from the bricks protects the blossoms from 

 being injured by the frosts. It is, however, neces- 

 sary to have a strong fire applied under the boiler 

 from the time the blossoms begin to expand, until 

 the fruit is set, and beginning to swell off, as the 



