460 



PITS AND FRAMES. 



would be kept up within the pit in every 

 part, and that motion would be increased 

 as the temperature is elevated, and the 

 supply of cold air increased. Atmospheric 

 heat is obtained by the two flow-pipes g g, 

 and single return-pipe k, connected to- 

 gether by a square box placed at any 

 convenient part of the end of the house 

 farthest from the boiler. The openings 

 of these three pipes being in the box, any 

 of them may be plugged to stop the cir- 

 culation in it when required. With such 

 an internal circulation, little top ventila- 

 tion, beyond that of the escape of the im- 

 pure air through the laps of the glass, will 

 be required. As the top sashes along the 

 front are movable, these may be opened, or 

 those over the passage, whichever is most 

 convenient. A shelf, i, is placed along 

 the back wall, on which French beans 

 may be cultivated. The bottom of the 



roof, both at back and front, is provided 

 with cast-iron gutters for collecting the 

 rain water for the use of the house, as 

 well as for keeping the walls dry. The 

 rain water should be conducted to the 

 cistern already noticed, and an overflow- 

 pipe led from it to an underground tank 

 either under the floor of the vault, or 

 outside the house, as may be most conve- 

 nient; or the water, as it is collected at 

 some height above the ground-level, may 

 be led into a tank above the surface, or 

 otherwise disposed of ; but by no means 

 should it be wasted by being carried into 

 a drain. 



For a very excellent cucumber-house, 

 vide Mr Moore's, fig. 359, in chapter Ven- 

 tilation. 



In such a house as that described 

 above, the cucumber vines are to be 

 trained to a trellis covering the whole roof, 



Fig. 651. 



