Professor Sir J. J. Thomson 



[March 18, 



angles to the direction of flight of the particles. I can do this by 

 means of the electro-magnet I will begin with a weak magnetic 

 force, representing a small spin. You see how the path differs from 

 the one when there was no magnetic force ; the path, to begin with, is 

 flatter though still concave, and the carry is greater than before— see 

 Fig. 17, a. I now increase the strength of the magnetic field, and you 

 will see that the carry is still further increased. Fig. 17, b. I increase 

 the spin still furthei, and the initial path becomes convex instead of 

 concave, with a still further increase in carry. Fig. 1.*^. Increasing the 



Fig. 19. 



force still more, you see the particle soars to a great height, then comes 

 suddenly down, the carry now being less than in the previous case 

 (Fig. 19). This is still a familiar type of the path of the golf ball. 

 I now increase the magnetic force still further, and now we get a type 

 of flight not to my knowledge ever observed in a golf ball, but which 

 would be produced if we could put on more spin than we are able to 

 do at present. You see there is a kink in the curve, and at one part 

 of the path the particle is actually travelling backwards (Fig. 20). 

 Increasing the magnetic force I get more kinks, and we have a type 



Fig. 20. 



Fig. 21. 



of drive which we have to leave to future generations of golfers to 

 realise (Fig. 21). 



By increasing the strength of the magnetic field I can make the 

 curvature so great that the particles flv back behind the tee, as in 

 Fig. 22. 



So far I have been considering under-spin. Let us now illustrate 

 slicing and pulling ; in these cases the ball is spinning about a 

 vertical axis. I must therefore move my electromagnet, and place it 

 so that it produces a vertical magnetic force (Fig. 28). I make the 

 force act one way, say downwards, and you see the particles curve 



