'voith bevelkd hollo'm Watts. 



the base (a), and 1%:. high; the back of the wall built per- 

 pendicalar {a b) with common bricks, and the inner part (c d) 



built of what are called flooring bricks, which are only about 

 2 in. thick. The cross bricks, which connect the two walls 

 together, are also built of these flooring bricks, set on edge. 

 The inner part of the wall bevels, or approaches to the outer 

 part of the wall, from the base to the height of 4 ft. {e\ where 

 it is reduced to 9 in. in thickness, at which width it is con- 

 tinued to the top. Immediately above the intended depth of 

 the soil of the pit (J") a course of bricks on edge is left out 

 both in the back and front walls of the pit, and the walls are 

 covered from one end to the other by a course of slates or 

 tiles, 9 in. wide {g). Above this the wall is continued hol- 

 low to the top, where it is furnished with a stone or wooden 

 coping in the usual way. The mould of the pit is supported 

 by cross bars of cast-iron, let into the back and front walls, on 

 which may be laid old boards, branches of fir and straw, pea- 

 sticks, or turves, as may be most convenient. The front wall 

 of the one pit {Ji) and the back wall of the other (/) are built 

 bevelling on both sides. The front wall of the second pit {k) 

 requires no description ; but it is necessary to observe, that 

 this second pit should be a foot lower in the soil than the back 

 one, in order that the latter may not be shaded by it. The 

 space between the pits (/) is for the purpose of applying a 

 lining to heat both pits ; it is covered with boards, which in- 

 cline to one side, and form a gutter at their lower angle {m), 

 for carrying off" the rain. In very severe weather linings of 

 litter {e) may i)e used to protect those parts of the walls which 

 are above ground. 



These pits are intended to be heated by dung, or any other 

 fermenting substance, introduced into the vault from doors at 

 one or both ends. While this fermenting substance supplies 

 a moist heat to the earth over it, it will also supply a dry heat 

 to the hollow side walls; which heat will enter the atmo- 



o 2 



