It is very easy indeed to test the rubber-cored balls as regards the correctness of their centre of gravity. Sir Ralph Payne-Gallwey found that none of the rubber-cored balls was correct as to its centre of gravity, though some were much more incorrect than others, and he found that not one of them was truly spherical in shape. I may say that in a large number of cases I have verified his experiments. Sir Ralph Payne-Gallwey's method of testing them for correctness of centre of gravity is so simple that I may give it here for the benefit of any player who desires to see that he is getting a ball which will serve him truly in so far as regards this important particular.

Sir Ralph placed the ball which he desired to test in a basin of water and waited until it came to rest. When the ball had come to rest, there was naturally a small portion of it protruding from the water. Sir Ralph marked the centre of this spot with a pencil dot and he found that however carelessly he put the same ball into the water, however much it was rolled about, that the portion of the ball marked with the pencil dot always came upwards out of the water again, and that the actual spot with the pencil mark on it always came to exactly the same place. It was evident from this that the centre of gravity of the balls tested in this manner was considerably untrue.

Sir Ralph found, as might be expected, that the old guttie ball was much truer as regards its centre of gravity than the rubber-cored balls. He tested the gutta-percha ball and the miniature ball which would not float in plain water, in a solution of salt and water.

The experiments which he conducted in connection with these balls were really quite exhaustive. He found that with some of the balls, especially the smaller ones, the dot appeared in two seconds, while some of the others took from four to six seconds to come upward. He arrived at a comparative idea of the error in centre of gravity by placing the dot downwards in the water, and then noting with a stop-watch the time occupied by it in appearing out of the water on top of the ball. He thus took the time in each case from the moment of release to the moment that the pencil dot again came uppermost, and by these means he obtained as accurately as he could with a stop-watch the comparative error of one ball with another in regard to its centre of gravity.

The testing of the balls for true spherical shape was, of course, easy, and was done by means of callipers. It can be done either by callipers or by a parallel vice which may be opened just wide enough to allow a ball to be passed between its jaws. If one has not a vice or callipers available, it is, of course, easy to cut a circle in a piece of cardboard and gradually increase the size of the circle until a ball will just get through. The circle, of course, must be made truly, but this can easily be done by a pin and a string if compasses are not available.

Of course, it would be advisable in testing a golf ball through a ring such as this to obtain in the first case a ball which is as near a true sphere as any rubber-cored ball can be. This may be done by fixing any two objects in a similar position to that suggested for the jaws of a vice, as for instance the opening of a drawer. One may open a drawer and fix the drawer firmly so that the ball can just pass in at the opening. Once this is done, it is almost as effectual as either callipers or the jaws of a vice.

Sir Ralph found that the gutties were as near true spheres as possible, and also that these balls showed very slight error in centre of gravity. This, of course, from the solidity of the matter and their original formation in the mould might naturally have been expected, for in the nature of the modern ball it stands to reason that its centre of gravity could never be so consistent as that of a ball which is made entirely in the one piece as was the old gutta-percha ball.

Sir Ralph has some remarkable projectile engines which gave him exceptional facilities for testing the flight of the golf balls which I sent him. He has one engine which weighs about two tons and is capable of casting a stone ball of twelve pounds a distance of a quarter of a mile. The catapult which he used for the purpose is a small reproduction of this big engine. His small model of this engine weighs about forty pounds and will pitch a golf ball from 180 to 200 yards, the distance of course depending upon the amount of tension used and the angle of elevation.

The power of the engine is obtained from twisted cord, and the arm of the machine used by Sir Ralph is two feet eight inches long, and is provided with a cup at its upper end to hold the ball. It is so arranged that the balls can be thrown any intermediate distance required up to 200 yards, and at any elevation. Sir Ralph conducted experiments with balls thrown by the catapult, and also with balls hit away by it in a manner similar to a golf club, and, as might be expected, no spin whatever was imparted to the ball. It was thrown in a straight line every time with unvarying accuracy, and there was not the slightest sign whatever of slice, pull, or cut. This, of course, is exactly what one who knows the principle of the catapult would expect.

Sir Ralph found, however, that the accuracy of flight of the ball was very remarkable, and he gives as an instance the fact that a ball which had been marked as having a particularly accurate flight was pitched twenty times in succession within a few feet of a stick stuck in the ground 180 yards from the machine.

It is interesting to note the weights of the balls used in these experiments. They varied from 22 drachms to 23 drachms avoirdupois, and their diameters from 53 to 54 thirty-seconds of an inch. The guttie ball used by Sir Ralph weighed 24 1/2 drachms, and one of the miniature balls 24 drachms 6 grains. Sir Ralph threw a dozen balls of various makes from his small engine at a mark 160 yards distant, and he threw each ball twenty times before another was tried. He employed a fore-caddie to mark the indentations each ball made where it fell. A peg was put in at the spot where each ball landed, and these distances were all subsequently measured, and the records kept for purposes of comparison.