The Scoop WheeL 75 



scoop makes with the surface of the water when first it comes 

 in contact with it, the outer end of the scoop being at the 

 apex of the angle. The angle of egress is that which the back 

 of the scoop makes with the surface of the water when it 

 leaves it, the end of the scoop as before being at the apex. 

 In the diagram Plate 2, fig. 5, A B C is the angle of ingress, 

 and D E F that of egress. 



In determining the angle of the scoop the mean level of the 

 water both on the interior and exterior side of the wheel must 

 first be settled. The centre of the wheel is then fixed so as 

 to divide the head and dip in equal proportions, except where 

 the lift is great, when the dip is seldom made to exceed 

 6 feet 



Owing to the variation in both the external and internal 

 water-levels, it is impossible to fix the scoops at such an 

 angle as that they shall always enter and leave the water in 

 the way most favourable to the discharge. The larger the 

 angle which the scoop forms with the surface of the water the 

 better the scoop enters, and the better hold it gets of the 

 water ; and the larger the angle of egress the better the water 

 leaves the scoops ; consequently the more the angle of ingress 

 is improved the worse becomes the delivery. If the angle of 

 ingress be too small, too much of the scoop comes in contact 

 with the water on first entering, and instead of drawing it 

 gently forward, beats it back, causing a disturbing element 

 detrimental to the discharge. If the angle of egress be too 

 small, the water does not drip off the scoop readily, but a 

 portion is carried up with it above the level of the surface of 

 the outfall, the height to which the part of the extra water is 

 lifted in some wheels due to this cause being as much as 6 feet 

 to 8 feet, while the remainder is lifted from 2 feet to 3 feet. 

 The undue work thrown on the engine from this cause may 

 be realised when it is considered that the lift of these wheels 

 seldom exceeds 10 feet, and is frequently only half this. 

 Mr. Beijerinck, the engineer of several reclamations in 



