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.

V

Now, however good the ball might be, the chances would be against a

perfect stillness upon any axis during flight; that is, of course, when

no initial spin was imparted to it by the way in which the stroke was

played. It would very likely turn just a little upon an axis, and that

little would unsteady and injure its flight, inasmuch as the wobble

would be from side to side alternately. This difficulty can be got over

by imparting an initial spin to the ball which will always be the same

all through its flight, and which will thus stop the wobbling. In a

word, rotation will steady the flight. This idea was originally at the

bottom of the rifling of the barrel through which a bullet is projected;

certainly it was the fundamental principle of the rifling of the old

32-pounders. Better to make the ball rotate on an axis that you know

about than that it should wobble on one you do not know about, they

said; and so the tubes were rifled inside, the balls were made to

rotate, and their flight was made steadier and therefore longer.

In the very earliest days of his investigations upon the flight of the

golf ball, Professor Tait thought of the application of this idea to the

game. A rotation should be given to the ball to steady its flight and

make it longer. A moment’s thought on the part of those whose

rudimentary scientific knowledge is a little rusty, will indicate that

there are three definite and clearly distinguished axes of rotation. One

is a vertical one, and it is chiefly upon that axis that the golf ball

rotates when it is pulled or sliced, or upon an axis that has something

of the vertical element in it. Then there is the horizontal axis, which

is at right angles to the line of flight; and this is the axis upon

which it rotates when either under-spin or top has been applied to it.

And, thirdly, there is the horizontal axis, which is parallel with the

line of flight. This is the axis upon which the rifle bullet spins. At

first Professor Tait was inclined to the idea that the last-named would

be the ideal axis for the rotation of the golf ball, but it happens to

be the one upon which it is impossible to make it rotate when struck by

a golf club. However, in this detail of his preliminary theorising he

was wrong, due entirely to his not having then investigated the virtues

of under-spin as always given to a ball when well driven, and not having

come by the great discovery that this under-spin helped the ball to

resist gravity and prolong its flight as nothing else could. How exactly

under-spin does this, we have just seen, and readers will now have a

very definite perception of the qualities of a ball and the importance

of rotation, and though the chief advantage of rotation is in resisting

gravity, it is an incidental advantage of it, as will now be understood,

that the flight of the ball is thereby steadied, and a very slight

inaccuracy in centering made of less consequence than it would otherwise

be. But remember that a considerable inaccuracy in centering will

interfere with the rotation, and therefore the bad flying ball can

still be distinguished, because it will fly badly.