IV
Golfers are in the way of saying that this ball “flies well” or that the other ball “does not fly well.” Sometimes it is imagination born of lack of form; but when great players concur it is not imagination. Some balls are obviously better than others—made of better material, better elastic thread, and more carefully constructed. There is an evident reason why such balls should fly better than others; that is to say, why they should go off the club more quickly, keep their place in the air longer, and travel farther. But then there are many balls of absolutely first-rate quality—and maximum price—that vary considerably in their flying properties, and it very commonly happens that even balls out of the same box, made at the same time and in the same way and of the same stuff, vary also. One frequently finds one or two “bad” balls in a box, and one or two very good ones. The excellent player very soon knows when he has come by the good ones and the bad ones. Now why, under such circumstances, should these balls vary so? What is it that makes them vary? Golfers in general do not know. Often enough they put it down to “pure cussedness”; others, to an idea that it is due to some accidental flaw in the manufacture. It is neither the one nor the other.
The scientific explanation is really a very simple one, and it was set forth very lucidly by Professor Tait. The perfect ball—using the adjective in its most absolute sense—is that which has its centre of gravity, that is to say its centre of weight, dead in the centre of the ball, the centre of measurement. It is by no means to be assumed that these two centres must necessarily coincide. For them to do so exactly is an ideal state, and while matter and man are what they are, and subject to their constant, even though slight, deviations, it is unattainable. But when a ball is properly cored and properly covered, most carefully and by the most exact machinery, the two centres come very near together, and generally, to all intents and purposes, do coincide. That they do not always do so exactly is merely because the greatest human effort is incapable of achieving the scientific ideal, and it must constantly happen that, despite all that effort, the distances between the two centres vary a little. Practically no effort can prevent it, particularly when the exigencies of circumstances demand that balls should be turned out weekly in tens of thousands, and at a price of not more than two shillings each. Now and again the separation of the centres will be greater than normal—accidental again—and then you get a really bad ball, with much bias upon it. When the centre of weight is not at centre of measurement, it means that the ball in effect is heavier on one side than the other, biassed, and that is practically equal to its being not round. Suppose you inserted a small piece of lead just inside the cover of a ball and closed it up again, shaping it as perfectly as it was before. The effect of this would be to remove the centre of weight very far towards that side, and you would have a great exaggeration of the difference between the two centres that commonly exists. If you laid that ball on a table it would promptly roll round until the weighted or biassed side were underneath. If you floated it in water it would wobble about until eventually it did the same thing; and if you floated it in air it would wobble again, and such wobbling would obviously be detrimental to its straight and even flight. There you have it. The farther the two centres are from each other—from the ideal state of absolute coincidence—the greater must be the tendency towards a wobbly or uneven flight, and diminished rotation, and consequently towards a short flight. In the case of many balls other than golf balls, these variations are very considerable. You have an extreme example when a football is out of shape, and it can be seen to make zigzags in the air. But the flight of footballs, or even cricket balls, is not such a delicate and susceptible thing as the flight of a golf ball at its far greater pace.
Professor Tait pointed out two very simple ways of finding out whether a golf ball had its two centres approximately coincident, and whether in consequence it ought to and would fly well. The first was by floating it in a bath of brine or mercury and noticing whether it wobbled or turned over. Many golfers are acquainted with this test, and employ it in a cruder and less decisive form by floating the ball in water. While a ball that had a fairly considerable separation between its two centres might not show any wobbling movement when floated in water, and consequently might not completely establish its claim to be properly centered and of good flying capacity so far as this part of its properties was concerned, the presumption would be greatly in its favour. On the other hand, that which did show any perceptible wobble in water would be self-condemned at once, and would undoubtedly be a bad flyer and a danger to the game of the good golfer.
The second test is one of comparison, and is exceedingly simple. You cannot compare the flying capacities of two or more balls by driving them with golf clubs, for however near to exact similarity you may think the strokes to have been, there is certain to have been an appreciable scientific and mathematical difference, such as would make a proper comparison impossible. But you may give practically exactly the same initial impetus in exactly the same circumstances to two or more balls by shooting them in the same direction from a crossbow, when the string is always pulled out to exactly the same point. Here you will have the balls flying under the simplest possible conditions, with no spin to complicate the flight and interfere with the comparison, and anyone who takes the trouble to make this experiment will find that some balls will regularly fly farther than others when shot forward in this manner. If the size and the weights are the same, these balls are better centered and better flyers, and it is an easy matter for any player to establish a standard by this test, and to judge of the perfection of any particular ball at a moment’s notice. Of course such a test takes no account of the resiliency of the ball; but then, as every player knows, there is a clear difference between good resiliency and good flying properties. In the old days of the gutta, when so much depended upon the even quality of the material all through the ball—and these were, of course, the days when Professor Tait made his investigations and experiments, and drew his conclusions—the variations between centres were greater than they are now, though not so great as in the early period of the rubber-core, when the winding and covering machinery were imperfect. Rubber-cored balls have lately begun to be covered by winding very thin strips of the covering material round the core in just the same way that the core itself is wound, and this should greatly conduce towards more accurate centering. An understanding of the foregoing will help the player towards an appreciation of some of the chief points of a good ball, and he will see how extreme is the necessity for perfect winding machinery and for the most careful supervision of the process. Nobody calls for a hand-made ball in these days: he wouldn’t get it if he did; and it wouldn’t be any good if he got it, for the chances would be enormously against its being so well centered as one made by machinery.