genemli^ in Use in WelbecJc Garden. 



453 



118 



and labour in the erection, by substituting stone lintels, in 

 place of " M'Phail's pigeonholes," to the north and south walls 

 which support the roof; and the suspended insulated posi- 

 tion of the pits, admits a circulation 

 of warm air, both under and all 

 round the pit of each light, where- 

 by a greater degree of surface tem- 

 perature is obtained in the absence 

 of solar rays, in the early forcing 

 season. 



Fig. 118. The ground-plan. 

 'U a a, the open-work end, and 

 the support for the north and south 

 lintels \bbb, bricks on edge, to sup- 

 port the bottom of the pits, and the surface hot air flues round 

 «ach pit. 



Mg. 119. The longitudinal sec- 

 tion, cc c c c, hot air flues, round 

 and under the bottom of the pit, 

 which are covered with a single tile. 

 When the bottom of the pit is 

 laid, the brick on edge is continued 

 up to the convenient height for the 

 surface hot air flues, which are also 

 covered with a single tile, laid the 

 reverse way to those at the bottom 

 of the pit. 



Fig.\'20. The transverse section showing the pits, an^ 

 position of the lintels, which admits the fermentative body of 

 manure to act under the north and south flues. 



120 



119 



The internal part of the pits is covered all over with a thin 

 •coat of hair-mortar, made rough by finishing it with a wood 

 float and brush ; and the tiles used here are the flat draining 

 ones, without knobs, which are free of the excise duty. 



G a 3 



