50G PROF. TAIT ON THE PATH OF A ROTATING SPHERICAL PROJECTILE. 



coefficient of resistance from the range, the time of flight, and the initial speed. But, 

 at present, I have no means of obtaining a more accurate approximation. 



25. The whole of this inquiry has been of a somewhat vague character, but its 

 value is probably enhanced, rather than lessened, in consequence. For the circum- 

 stances can never be the same in any two drives, even if they are essentially good ones, 

 and made by the same player. To give only an instance or two of reasons for this : — 

 Two balls of equal mass may have considerably different coefficients of resistance in 

 consequence of an apparently trifling difference of diameters, or of the amount or 

 character of the hammering : — or they may have very different amounts of resilience, due 

 to comparatively slight differences of temperature or pressure during their treatment in 

 the mould. The pace which the player can give the club-head at the moment of 

 impact depends to a very considerable extent on the relative motion of his two hands 

 (to which is due the " nip ") during the immediately preceding two-hundredth of a 

 second, while the amount of beneficial spin is seriously diminished by even a trifling 

 upward concavity of the path of the head during the ten-thousandth of a second 

 occupied by the blow. It is mainly in apparently trivial matters like these, which are 

 placidly spoken of by the mass of golfers under the general title of " knack," that lie 

 the very great differences in drives effected, under precisely similar external conditions, 

 by players equal in strength, agility, and (except to an extremely well-trained and 

 critical eye) even in style. 



[Oct. 5, 1898. — The printing of this paper has been postponed for nearly three 

 years in the hope, not as yet realised, that I might be able to determine accurately by 

 experiment the terminal speed of an average golf-ball, as well as the average value of k, 

 when (as in § 5) katv represents the transverse acceleration, in terms of the rates of spin 

 and translation. Another object has been to measure the effect of rapid rotation upon 

 the coefficient of resistance to translatory motion. These experiments, in various forms, 

 are still being carried out by means of various modes of propulsion, from a cross-bow to 

 a harpoon-gun. I hope also to procure data, for speed and resistance, applicable to 

 various other projectiles such as cricket- balls, arrows, bird-bolts, etc.] 



PRE^TTED 



17 MAR. 1899 



