12^ 



POLMAISE MODE OF HEATING GREEN-HOUSES» 



CRECNHOUSE 30X15 



LEVEL OF FLOOR 



y /o* 



UrOKITHOLE 



LEV£L OF FLOOK OF HOT. CHAMBER 



* * The eold-air main drain would have acted equally well, 

 perhaps belter, if constructed on this plan, keeping il horizon- 

 tal, or only slightly inclined, with a sudden downward shaft to 

 the floor of Hot Chamber. This would save much excava- 

 tion. 



t \ Portion of cold-air main drain, having an opening 3 

 feet wide and 1 fool broad, at the farther end of Green-house 

 inside ; this opening is below a flat stajre for flowers. The 

 drain is 3 feet wide, 1 deep, formed at the sides of brick on 

 edge, covered over with any roogh paving tiles, elates, or 

 flagging. 



