198 THE POPULAR SCIENCE MONTHLY 



against it horizontally from left to right. Evidently, however, in this 

 case the ball would tend to roll up the face, and would thus get spin 

 about a horizontal axis in the direction shown in the figure; this is 

 underspin, and produces the upward force which tends to increase the 

 carry of the ball. 



Suppose, now, the face of the club is not square to its direction of 

 motion, but that looking down on the club its line of motion when 

 it strikes the ball is along PQ (Fig. 28), such a motion as would be 

 produced if the arms were pulled in at the end of the stroke, the effect 

 of the impact now will be the same as if the club were at rest and the 

 ball projected along RS, the ball will endeavor to roll along the face 

 away from the striker ; it will spin in the direction shown in the figure 

 about a vertical axis. This, as we have seen, is the spin which produces 

 a slice. The same spin would be produced if the motion of the club 

 were along LM and the face turned so as to be in the position shown 

 in Fig. 29, i. e., with the heel in front of the toe. 



If the motion and position of the club were as in Figs. 30 and 31, 

 instead of as in Figs. 28 and 29, the same consideration would show 

 that the spin would be that possessed by a pulled ball. 



