11)10] The Dynamics of a Golf Ball. 795 



AVEEKLY EVENING MEETING, 



Friday, March l.s. 1910. 



Sir James Crichtox-Browne, M.D. LL.D. D.Sc. F.R.S., 

 Treasurer and Vice-President, in tlie Chair. 



Professor Sir J. J. Thomson, M.xl. LL.D. D.Sc. F.R.S. M.R.I., 

 Professor of Natural Philosophy, Royal Institution. 



The Dynamics of a Golf Ball. 



There are so many dynamical problems connected with golf that a 

 discussion of the whole of them would occupy far more time than is 

 at my disposal this evening. I shall not attempt to deal with the 

 many important questions which arise when we consider the impact 

 of the club with the ball, but confine myself to the consideration of 

 the flight of the baU after it has left the club. This problem is in 

 any case a very interesting one, it w^ould be even more interesting if 

 we could accept the explanations of the behaviour of the ball given 

 by many contributors to the very voluminous literature which has 

 collected round the game ; if these were correct, I should have to 

 bring before you this evening a new dynamics, and announce that 

 matter when made up into golf balls obeys laws of an entirely differ- 

 ent character from those governing its action when in any other 

 condition. 



If we could send off the ball from the club, as we might from a 

 catapult, without spin, its behaviour would be regular, but uninterest- 

 ing ; in the absence of wind its path would keep in a vertical plane, 

 it would not deviate either to the right or to the left, and would fall 

 to the ground after a comparatively short carry. 



But a golf ball when it leaves -the club is only in rare cases de- 

 void of spin, and it is spin which gives the interest, variety, and 

 vivacity to the flight of the ball. It is spin which accounts for the 

 behaviour of a sliced or pulled ball, it is spin which makes the ball 

 soar or " douk," or execute those wild flourishes which give the im- 

 pression that the ball is endowed with an artistic temperament, and 

 performs these eccentricities as an acrobat might throw in an extra 

 somersault or two for the fun of the thing. This view, however, 

 gives an entirely wrong impression of the temperament of a golf ball, 

 which is in reality the most prosaic of things, knowing while in the air 

 only one rule of conduct, which it obeys with unintelligent conscien- 

 tiousness, that of always following its nose. This rule is the key to 

 the behaviour of all balls when in the air, whether they are golf balls, 

 base balls, cricket baUs, or tennis balls. Let us, before entering into 



