12 FRUIT TREES IN POTS [ch. 



say 5 ft. or 5 ft. 6 ins., according to the size of the 

 house, as this will give good head space for the trees. 

 The front and top ventilators should be of the 

 same size as those of the span-roofed house, and 

 in addition to these (if it be possible) there should 

 be some ventilators in the back wall. These might 

 take the form of flaps or slides, whichever is pre- 

 ferred, and should be about 3 ft. long and 1 ft. 

 wide, and 6 ft. apart. These ventilators will be of 

 great service, as they will be the outlets for any 

 stagnant or hot air which is sure to be found in 

 the back of " lean-to houses." Below is a rough 

 diagram of the back of a lean-to house, showing 

 how the ventilators may be arranged. 



EOOF 



Floor 



It will be noticed in the diagram that there 

 are two rows of ventilators placed altex'nately, at 

 equal distances, from both roof and floor of house. 

 If the house is a small one, one row of ventilators 



