VENTILATION 



71 



in on the windward side, behaving much as just described, 

 striking the ground and driving the upper stratum of air 

 through the leeward side of the ridge. If the incoming 

 velocity is very great the air may traverse the stable, 



Fig- 7. — Direction taken by air currents with windward and leeward 

 windows open. 



and pass out at the opposite window without mixing 

 (Fig 7.) 



A double incoming current from opposite windows may 

 frequently though often momentarily be detected (Fig. 8) ; 

 the two meet in the centre of the stable, and the ridge acts as 

 the outlet. The double current lasts but a short time, and 



Fig. 8. — Double current from opposite windows. 



is replaced by the single inlet and opposite outlet, which in 

 due time is again disturbed. 



When opposite windows are half open (Fig. 9), and thus 

 resemble Sheringham windows in construction, the chief 

 difference observable is the height to which the incoming 



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