TENNIS BALLS

Hokitika Guardian, 9 November 1929, Page 3

TENNIS BALLS

TESTING OPERATIONS. A recent visitor from New Zealand while in England was shown through a large ball manufacturing factory in Birmingham. The test to which every one of the thousands of balls made in this factory is subjected is a most remarkable one. . "j Each ball when made is put on a long moving tray and the happenings on the way oi its journey are most interestmgA little distance along is stationed a girl. She examines each ball as it gets to her. Those she rejects are placed in a chute which carries them off to a place where they are destroyed. Those she passes she places again on the moving tray where they, are carried on to a second girl who also .subjects them to'examination rejecting in., the same way as the first girl balls' she thinks are imperfect in make. Further along still is a third girl who makes a final examination. These three, .tests - are known as the compression' tests. Those balls she passes are still carried on the tray up «a height of TOO inches for the bounce test. The balls fall from this height on to a polished surface which slants slightly outward. This slight slant makes the ball bounce up and forward. This forward bounce is necessary because the ball has to clear a hurdle 53 inches high. Five inches above this (making 58 inches from the polish surface) is a bar. If the ball fails to clear the 53-inch hurdle it is immediately rejected. If it strikes above the bar 58 inches from the surface it is also rejected. If it clears the hurdle and goes through the opening between the top’of the hurdle and the bar it is fit to go on to the next test .which is well-named the destruction test.

This test is a most ingenious one. The ball falls into a basement affair in which there are four rackets fixed to a very fast revolving wheel, and wonderfully timed for the purpose they are meant for. As each ball comes into this basement is a smashed by these rackets thirty times. The principle employed is the same as is frequently seen being indulged in by some players at a club when practising against a volley board. The ball is hit by one of the rackets on to a polished surface floor that slants away. The ball bounces off this surface against the volleying wall and so up high towards another revolving racket which smashes the hall down again and so on until thirty times. At the thirthieth time the volley wall automatically drops and the ball is thrown out to repeat in its entirety the process already described before going through the final test. This last test is one of size. The rules provide that a ball shall be more than two and a half inches and less than two and five-eights inches in diameter. The balls are brought to a place where there are three holes of different sizes, but within the limits of the international test for size. The balls as they fall through one of these holes are collected in separate baskets ready to lie placed in boxes to be marketed. A box is filled only with balls that have fallen through the same hole so that players may be assured that balls from the same box are in all res-