VENTILATION 113 



in its action that considerable diffusion takes place through lum- 

 ber and ordinary brick, and other building materials. 



Air Currents 



An entering current of air has the effect of inducing other 

 currents within the stable, tlie induced currents setting in at 

 right angles to the inlet current. 



With AvhidoAVs wide open to windward, and openings on the 

 other side of the stable closed, and with ridge ventilation, it is 

 found ^ that the current of air rushes in, strikes tlie floor at a 

 variable distance after spreading out somewhat, then rises and 

 most of it passes out at the ridge. A current decreases rapidly 

 in velocity after the first five or six feet from the inlet. The 

 atmosphere immediately under the inlet is l)ut moderately dis- 

 turbed. 



When opposite windows are open, the air comes in from the 

 windward side, strikes the ground, rises again, and a consider- 

 able portion passes directly out at the opposite side. But a sud- 

 den change in the outside currents may temporarily reverse 

 this series. 



The exact movement of air within the stable is varied, of 

 course, by stall partitions and other obstructions. 



A strong wind passing over a stable provided with ventilating 

 shaft has an outward suction effect, and this is increased by a 

 properly constructed cap which does not permit the entrance 

 of outside air from below. 



' Paige. 



