The Soul of Golf Part 17

This problem is in any case a very interesting one, which would be even more interesting if we could accept the explanations of the behaviour of the ball given by some contributors to the very voluminous literature which has collected around the game. If this were correct, I should have to bring before you this evening a new dynamics and announce that matter when made up into golf b.a.l.l.s obeys laws of an entirely different character from those governing its action when in any other condition.

This, at the outset, is an extremely remarkable statement to come from so eminent a physicist, for I may say that Professor Thomson, after making a remark of this nature, proceeds to explain the phenomena of swerve on exactly the same links which I have set out fully and explicitly in my book _Swerve, or the Flight of the Ball_. That, however, is a matter of small importance. It may be that Professor Thomson has not had the opportunity of perusing this book. It may indeed be that Professor Thomson has been unfortunate enough only to have read articles wherein an erroneous explanation of the well-known phenomena of the flight of the ball is given. Be that as it may, there can be no doubt that the explanation which has been given of the causes of swerve has been adequate and accurate, and there would not have been any necessity whatever for Professor Thomson to bring before the learned Inst.i.tution whose fellows listened to his address "a new dynamics." It would have been sufficient if he had correctly explained the phenomena of the flight and run of a golf ball according to the well-recognised laws which govern the flight and run of all b.a.l.l.s.

This, however, he quite failed to do.

Professor Thomson says: "If we could send off the ball from the club as we might from a catapult, without spin, its behaviour would be regular, but uninteresting." It is quite possible to send a golf ball off a club without spin. It is just as possible, from a practical point of view, to send a golf ball away without spin from the face of a driver as it is from the pouch of a catapult. The catapult is a machine, and it is a certainty that it can be made to propel a golf ball without any initial spin whatever. A machine can be made to drive a golf ball with just as little spin, and as a matter of practical golf, by far the greater number of golf b.a.l.l.s are driven without appreciable spin--that is to say, without spin which has any definite action on the flight of the ball.

The learned lecturer says: "A golf ball when it leaves a club is only in rare cases devoid of spin." It is impossible to prove or disprove this statement, for practically no ball goes through the air with the same point always in front. We may see this quite clearly if we care to mark a lawn-tennis ball, and to hit it perfectly truly, and slowly, so that it goes almost as a lob across the net. We shall see even then that the marked part of the ball moves from one place to another. In fact, even if a golf ball were driven by a machine which did not impart to it any initial spin, it is almost a certainty that that ball would not have proceeded far before it had acquired sufficient motion to justify one in technically calling it spin. Spin, however, is a delightfully indefinite word, but this much one may at least say, and it is, in effect, a contradiction of Sir J. J. Thomson's a.s.sertion, namely that in the vast majority of b.a.l.l.s. .h.i.t with golf clubs, especially by skilled players, the effect of spin on the stroke _unless designedly applied_, which is comparatively rare, is practically negligible.

Professor Thomson says that

... a golf ball, when it leaves the club, is only in rare cases devoid 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 impression 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 an intelligent conscientiousness, that of always following its nose. This rule is the key to the behaviour of all b.a.l.l.s when in the air, whether they are golf b.a.l.l.s, base-b.a.l.l.s, cricket b.a.l.l.s, or tennis b.a.l.l.s.

The idea of a spherical object having a nose is so unscientific and so inexact that it is not necessary for me to dwell very strongly on it here, and I should not do so were it not that this looseness of description is of considerable importance in dealing with Professor Thomson's ideas. He continues:

Let us, before entering into the reasons for this rule, trace out some of its consequences. By the nose on the ball we mean the point on the ball furthest in front.

It will be obvious to my readers that this description is scientifically extremely inaccurate, for if we take a line through the ball from the point of contact with the club to the point on the ball farthest in front, which Professor Thomson calls its nose, we shall find that the flight of that ball will always be in that same line produced, whereas in the spinning ball it is nothing of the sort. The whole trouble here is that Professor Thomson wants to have the "nose,"

as he calls it, of the ball, both a fixed and a moving point. This, obviously, is most unscientific. If the nose of the ball is the point that is farthest in front, I cannot say too emphatically that it stands to reason that the ball in flight will go straight out after that point, but the fact is that the point in front is continually changing; moreover, the fact that the ball goes the way it is spinning is not explained by any tendency of the ball to wander that way on account of the spin irrespective of the friction of the air.

It will thus be seen that Professor Thomson's explanation in this matter is incorrect and misleading. This is about the most unscientific explanation which could be given of this matter, and it is one which is calculated to mislead people who would otherwise understand the matter quite clearly, so we shall drop Professor Thomson's idea of giving the ball a "nose" which is always in the front of it, but which is also supposed to be continually travelling sideways. It is obvious that Professor Thomson cannot have it both ways.

It is very clear indeed that Professor Thomson is not well acquainted with the method of applying spin to b.a.l.l.s which are used in playing games. He says:

A lawn-tennis player avails himself of the effect of spin when he puts "top-spin" on his drives, _i.e._ hits the ball on the top so as to make it spin about a horizontal axis, the nose of the ball travelling downwards as in figure 4; this makes the ball fall more quickly than it otherwise would, and thus tends to prevent it going out of the court.

I have played lawn-tennis for more than twenty years, and I am the author of three books on the game, one of which is supposed to be the standard work on the subject, and I can a.s.sure Professor Thomson that no lawn-tennis player would dream of doing anything so silly as to hit a lawn-tennis ball "on the top" in an attempt to obtain "top-spin."

The scientific method of obtaining top-spin is to hit the lawn-tennis ball on what Professor Thomson, if he were driving the ball over the net to me, would call its nose--that is to say, I should hit the ball on the spot which was farthest from Professor Thomson. I should hit it there with a racket whose face was practically vertical, but I should hit it an upward, forwardly glancing blow which would impart, as Professor Thomson expresses it, "spin about a horizontal axis to the ball."

Professor Thomson goes so far as to show by diagram the travel of a ball which has been hit so as to impart top-spin to it, but even in this diagram he is absolutely wrong, for he shows that immediately the ball has been hit with top-spin it begins to fall, but this is not so.

In lawn-tennis the ball travels for a long distance before the spin begins to a.s.sert itself, and to overcome the force of the blow which set up the spin.

Professor Tait makes this same error in his article on "Long Driving,"

and it is quite evident to me that Professor Thomson is following, in many respects, the errors of his eminent predecessor.

Professor Thomson also says:

Excellent examples of the effect of spin on the flight of a ball in the air are afforded in the game of base-ball. An expert pitcher, by putting on the proper spin, can make the ball curve either to the right or the left, upwards or downwards; for the side-way curves the spin must be about a vertical axis; for the upward or downward ones, about a horizontal axis.

There are no particular laws with regard to the curves of a base-ball.

The same laws regulate the curves in the air of every ball from a ping-pong ball to a cricket ball, and Professor Thomson, in saying that "for the side-way curves the spin must be about a vertical axis,"

is absolutely wrong. Every lawn-tennis player who knows anything whatever about the American service, will know that Professor Thomson is utterly wrong in this respect, for the whole essence of the swerve and break of the American service, which has a large amount of side-swerve, is that the axis of rotation shall be approximately at an angle of fifty degrees, and any expert base-ball pitcher will know quite well that he can get his side-curve much better if he will, instead of keeping his axis of rotation perfectly vertical, tilt it a little so that it will have the a.s.sistance of gravitation at the end of its flight instead of fighting gravitation, as it must do if he trusts entirely to horizontal spin about a vertical axis for his swerve.

Professor Thomson says:

If the ball were spinning about an axis along the line of flight, the axis of spin would pa.s.s through the nose of the ball, and the spin would not affect the motion of the nose; the ball, following its nose, would thus move on without deviation.

The spin which Professor Thomson is describing here is that which a rifle bullet has during its flight, for it is obvious that the rifle bullet is spinning "about an axis along the line of flight," and that the axis of spin does pa.s.s through the nose of the bullet, but we know quite well that in the flight of a rifle bullet there is a very considerable amount of what is called drift. It is, of course, an impossibility to impart to a golf ball during the drive any such spin as that of the rifle bullet, although in cut mashie strokes, and in cutting round a stymie, we do produce a spin which is, in effect, the same spin, but this is the question which Professor Thomson should set himself to answer. He states distinctly that a ball with this spin would not swerve. If this is so, can Professor Thomson explain to us why the rifle bullet drifts? As a matter of fact, a ball with this spin _would_ swerve, but not to anything like the same extent as would a ball with one of the well-recognised spins which are used for the purpose of obtaining swerve.

[Ill.u.s.tration: PLATE XI. JAMES BRAID

Finish of drive, showing clearly how Braid's weight goes on to the left leg.]

Professor Thomson proceeded to prove by the most elaborate experiments the truth of those matters stated by Newton centuries ago, but it will not be necessary for me to follow him in these, because these principles have been recognised for ages past.

It is curious to note that in the reference to Newton, who was aware of this principle of swerve so long ago, we are shown that Newton himself did not quite grasp the method of production of the stroke, although he a.n.a.lysed the result in a perfectly sound manner. Writing to Oldenburg in 1671 about the Dispersion of Light, he said in the course of his letter: "I remembered that I had often seen a tennis ball struck with an oblique racket describe such a curved line." The effect of striking a tennis ball with an oblique racket is, generally speaking, to push it away to one side. The curve, to be of a sufficiently p.r.o.nounced nature to be visible, must be produced by the pa.s.sage of the racket across the intended line of flight of the ball.

This matter of the different pressure on one side of the ball from that on the other is very simple when one thoroughly grasps it.

Professor Thomson gives in his paper an ill.u.s.tration which may perhaps make the matter clearer to some people than the explanation which is generally given. He says:

It may perhaps make the explanation of this difference of pressure easier if we take a somewhat commonplace example of a similar fact. Instead of a golf ball let us consider the case of an Atlantic liner, and, to imitate the rotation of the ball, let us suppose that the pa.s.sengers are taking their morning walk on the promenade deck, all circulating round the same way. When they are on one side of the boat they have to face the wind, on the other side they have the wind at their backs. Now, when they face the wind, the pressure of the wind against them is greater than if they were at rest, and this increased pressure is exerted in all directions and so acts against the part of the ship adjacent to the deck; when they are moving with their backs to the wind, the pressure against their backs is not so great as when they were still, so the pressure acting against this side of the ship will not be so great. Thus the rotation of the pa.s.sengers will increase the pressure on the side of the ship when they are facing the wind, and diminish it on the other side. This case is quite a.n.a.logous to that of the golf ball.

Even in this simple ill.u.s.tration it seems to me that Professor Thomson is wrong, for he is pre-supposing that which he does not state--a head wind. It is quite obvious that these pa.s.sengers might have to face a wind coming from the stern of the ship, and in this case the a.n.a.logy between the pa.s.sengers circulating round the deck of a ship, and his golf ball would receive a serious blow. In stating a matter which is of sufficient importance to be dealt with before such a learned body as the Royal Inst.i.tution of Great Britain, it is well to be accurate.

If Professor Thomson had stated that his Atlantic liner was going into a head wind, or, for the matter of that, even proceeding in a dead calm, his a.n.a.logy might have been correct, but it is obvious that he has left out of consideration a following wind of greater speed than that at which the liner is travelling.

Professor Thomson has not added anything to the information which we already possessed with regard to the effect of back-spin on a ball; rather has he, as I shall show when dealing with the question of impact with the ball, clouded the issue. At page 12 of his remarkable lecture he says: "So far I have been considering under-spin. Let us now ill.u.s.trate slicing and pulling; in these cases the ball is spinning about a vertical axis." We here have a very definite statement that in slicing and pulling the ball is spinning about a vertical axis, but it is not doing so.

Professor Thomson has "an electromagnet and a red hot piece of platinum with a spot of barium oxide upon it. The platinum is connected with an electric battery which causes negatively electrified particles to fly off the barium and travel down the gla.s.s tube in which the platinum strip is contained; nearly all the air has been exhausted from this tube. These particles are luminous, so that the path they take is very easily observed."

These particles, I may explain, take, in Professor Thomson's mind, the place of golf b.a.l.l.s, and by an electromagnet he shows us exactly what golf b.a.l.l.s do, but it seems to me that if Professor Thomson is not absolutely clear what is happening to the sliced ball and the pulled ball, there is a very great chance that, like Professor Tait, he may induce his particles to do the thing that he wishes them to do, and not the thing that a real golf ball with a real pull or a real slice would do. This, as a matter of fact, is exactly what Professor Thomson does, for, as I shall show quite simply and in such a manner as absolutely to convince the merest tyro at golf, Professor Thomson is utterly wrong when he states that in the slice and the pull the ball is spinning about a vertical axis.

I shall not need any diagrams or figures to bring this home to anyone who is possessed of the most rudimentary knowledge of mechanics. It should be quite evident to anyone that to produce spin about a vertical axis it would be necessary to have a club with a vertical face, or to strike a blow with the face of the club so held that at the moment of impact the face of the club was vertical. Now this does not happen with the slice at golf, for the very good reason that if one so applied one's club, the ball would not rise from the earth. The club which produces the slice is always lofted in a greater or less degree, and quite often the natural loft is increased by the player designedly laying the face back during the stroke. It is evident that in the impact with the driver or bra.s.sy, the ball, especially the modern rubber-cored ball, flattens on to the face of the club and remains there whilst the club is travelling across the line of flight.

This naturally imparts to the ball a roll--in other words, as the club cuts across the ball it rolls it for a short distance on its face.

It is obvious that this rolling process will, to a greater or less extent, give to the ball a spin about an axis which is approximately the same as that of the loft on the face of the club. Therefore, it is clear that in all sliced b.a.l.l.s the axis of spin will be inclined backward. It seems likely, also, that as the axis of spin is inclined backward and the ball is rising, there will be some additional friction at the bottom of it which would not be there in the case of a ball without spin. This probably helps to produce the sudden rise of the slice. In all good cut shots with lofted clubs, the angle of the axis of spin is to a very great extent regulated by the amount of loft on the face of the club.

Professor Thomson's error with regard to the slice being about a vertical axis is beyond question, but his error in saying that the axis of rotation of the pull and the slice is identical, is, from a golfing point of view, simply irretrievable. Print is a very awkward thing--_it stays_. The merest tyro at golf knows quite well that the pulled ball and the sliced ball behave during flight and after landing on the ground in a totally different manner from each other. If Professor Thomson knows so much, it should unquestionably be evident to so distinguished a scientist that there must be a very considerable difference in the rotation of these b.a.l.l.s. The slice, as is well known, rises quickly from the ground, flies high, and is not, generally speaking, a good runner. The pull, on the other hand, flies low and runs well on landing.

It is not merely sufficient to contradict Professor Sir J. J. Thomson in these matters, so I shall explain fully the reason for the difference in the flight and run of the slice and the pull. The slice is played as the club head is returning across the line of flight, and therefore is more in the nature of a chop than is the pull. Frequently the spin that is imparted to the ball is the resultant of the downward and inwardly glancing blow. This not only leaves the axis of rotation inclined backward, but sometimes inclined also slightly away from the player, but it is obvious that even if the ball had, as Professor Thomson thinks it has, rotation about a vertical axis, which is the rotation of a top, such rotation would, on landing, tend to prevent the ball running, for, as is well known, every spinning thing strives hard to remain in the plane of its rotation, but the slice is more obstinate still than this, for the axis of rotation being inclined backward, frequently at the end of the flight, coincides with the line of flight of the ball, so that the ball is spinning about an axis which, to adopt Professor Thomson's term, runs through its "nose."

This means that the slice frequently pitches in the same manner as might a rifle bullet if falling on its "nose," and the effect is, to a very great extent, the same. The ball tries to stay where it lands.

Let us now consider the flight and run of the pull. The pull is played by an upward, outward, glancing blow. The ball is. .h.i.t by the club as it is going across the line of flight away from the player and this imparts to the ball a spin around an axis which lies inward towards the player. This means that the pull goes away to the right, and then swerves back again towards the middle of the course if properly played, and upon landing runs very freely. The reason for this run has not been clearly understood by many, and it is quite evident that Professor Thomson does not know of it, so I shall give an extremely plain ill.u.s.tration.

Nearly every boy has at some time played with a chameleon top, or some other top of the same species, that is to say, a disc top. Every boy who has played with such a top will be familiar with the fact that when the spin is dying away from the top, it rolls about until one edge of it touches the earth or whatever it is spinning on.

Immediately this happens the top runs away as carried by the spin.

That is about the simplest ill.u.s.tration which it is possible to give of the plane of spin of the pulled ball during its flight and of its run after it has touched the earth, but from this very simple explanation it will be perfectly obvious to anyone who gives the matter the least consideration that not only is the axis of rotation of the pull and the slice dissimilar, but as a matter of fact the rotation of the pull and the slice is almost diametrically opposed the one to the other.

Professor Thomson says:

Let us now consider the effect of a cross wind. Suppose the wind is blowing from left to right, then, if the ball is pulled, it will be rotating in the direction shown in figure 26 (from right to left); the rules we found for the effect of rotation on the difference of pressure on the two sides of a ball in a blast of air show that in this case the pressure on the front half of the ball will be greater than that on the rear half, and thus tend to stop the flight of the ball. If, however, the spin was that for a slice, the pressure on the rear half would be greater than the pressure in front, so that the difference in pressure would tend to push on the ball and make it travel further than it otherwise would.

I have not given this aspect of the question a great amount of thought, but it seems obvious that in playing for a slice in the circ.u.mstances mentioned by Professor Thomson, it is extremely unlikely that the greater pressure would be, as he says, on the rear half. If, indeed, this were so the slice would, in my opinion, not take effect; also on account of the tremendous speed of the golf ball it seems to me utterly improbable that in any ordinary wind which one encounters on a golf links it would be possible to obtain on the rear half of a golf ball a greater pressure than that on the forward spinning half, or, to be more accurate, quarter of the ball. I cannot help thinking that Professor Thomson in saying that in such a case as this the greater pressure would be on the rear half of the ball is falling into an error, for it seems to me that he is overlooking the tendency of the ball to set up for itself something in the nature of a vacuum which will undoubtedly tend to protect the rear portion of the ball from the force which must a.s.sail it in front during its pa.s.sage through the air.

Professor Thomson says that "the moral of this is that if the wind is coming from the left we should play up into the wind and slice the ball, while if it is coming from the right we should play up into it and pull the ball."

That is Professor Thomson's theory. I shall give my readers the benefit of my practice, which is that whenever there is a cross wind of any description whatever, hit the ball as straight as it is possible for you to do it, right down the middle of the course from the tee to the hole, and forget all about pulls or slices. On a windy day avoid anything whatever in the nature of side-spin because once you have applied it to a ball you never know where that ball is going to end, and if you want any confirmation for this practice you may get it from Harry Vardon in _The Complete Golfer_, for there can be very little doubt that a side wind has nothing like the effect on the ball that golfers seem to imagine, provided always, of course, that the ball be hit cleanly and without appreciable spin. It is not given to one golfer in a thousand to know how to use the pull and slice to obtain a.s.sistance from the wind and also to be capable of executing the strokes. As a matter of practical golf these strokes should, for at least ninety-five per cent of golfers, be rigidly eschewed.