

EFFLUX FROM LATERAL ORIFICES. 



199 



right ; and if the vessel is easily moveable, the excess 

 of pressure on the left wall would move the vessel 

 towards the left. In a similar manner, whenever liquid 

 is discharged from an aperture, the side opposite to it 

 is pressed in a direction contrary to that of the 

 issuing jet; this pressure may be called the reaction of 

 efflux. 



FIG. 143 (A, an. proj. ~ real size, B \ real size), 



Motion may be produced by this reaction by means 

 of an apparatus usually called Barker's wheel, the form 

 of which is shown in fig. 143 A, while fig. 143 B is a 

 section of the lower part. The efflux takes place 

 through the orifices a and 6, and its reaction causes a 

 rotation in the direction of the arrow r. The effect of 

 this reaction has been actually employed on a large 

 scale for moving machinery by means of water; such 



