THROWING ROUND A CORNER. 



line to the right at C, instead of going on in 

 its original direction to D. 



If the ball receive the opposite horizontal 

 spin as at E, then its face, which is pressed 

 against the air in front, moves in the direction 

 F, and drives the air in that direction. Con- 

 sequently the ball itself, moving, as before, 

 in the opposite direction, goes to the left along 

 the dotted line to G. 



Next let the ball at the moment of being 

 thrown receive a vertical spin sideways about 

 a horizontal axis, the arrow at H showing the 

 direction of its upper surface, and that at K 

 the direction of its lower surface. 



At first this spin will not deflect the ball 

 from its line of flight H L. But when it has 

 travelled some distance, and had time to 

 acquire considerable falling movement, its lower 

 surface presses the air more forcibly than its 

 upper surface, and, pushing the air aside in 

 the direction K, is itself deflected in the oppo- 

 site direction to M, 



Similarly a spin in the opposite direction, the 

 upper surface moving as at N, and the lower as at 

 O, results in the ball being deflected towards P. 



There are yet two other chief ways in which 

 a ball may spin during its flight. In these the 

 plane of spinning is vertical and directed in 

 the line of flight. 



Q shows the upper surface of the ball spin- 

 ning forwards towards the same point S to 



45 



