SPEED TESTS.

Otago Daily Times, Issue 19001, 25 October 1923, Page 4

SPEED TESTS.

TENNIS, GOLF, AND CRICKET BALLS. “A most interesting series of experiments has just been carried out at Cambridge to establish with absolute scientific accuracy the initial velocity of the ball in lawn tennis, golf, and crickqt (bowling and throwing),” says Mr A. E. Crawley, m Ids recent book, “The Technique of Hawn Tennis.” “The recording instrument is the oallistic pendulum.” This is a wooden box, 3ft x Ift by Ift, with an open end. It is suspended by wires irom the ceiling, and is stuffed lightly with cotton wool. Its weight is correctly ascertained, as also that of the ball, and the time occupied by tlie swing of the pendulum. The recoil ol the box in fractions of an inch is recorded on a gauge, and a mathematical calculation transposes the result into foot-seconds hoot-seconds are more intelligible than miles an hour for the short distances ip games.

“As would have been expected the initial velocity of a driven golf ball is the greatest. The best drives of one of the best Cam bridge golfers varied between 215 and 220 feet a second- Probably the best drivers in the world would secure 250 foot-seconds Of course, tho spin and speed (with air resistance) rapidly slow down the golf nail's rate.

The cricket bowling results arc unes pected; the fastest recorded are 85 loot seconds only. Throwing the cricket oali registered 108 foot-seconds. “Again, one would have thought a fast bowler was faster than a bust server at lawn tennis. But service registered on the average 120 feet a second. On the other hand, this initial velocity is slow'ed down sooner than that of a cricket ball because the latter projectile is heavier. It is easy to calculate that the batsman playing c fast bowler lias less than one second to view the flight of the bail, ana that tile receiver in lawn tennis has less.

“In regard to the served tennis bali, the movement is that of a throw, but the resmv is faster than a throw, just because of the added resiliency—reaction between the gut strings and the rubber ball. Considered in the light of pure mathematics, Loney s example in his ‘Dynamics’ is absolutely sound. It is a very clever problem. A player at lawn tennis serves a ball roni the height of Bft, the ball bits the top of the net, which is 3ft 3in high, and (ouches tiie service line. Therefore, the mean velocity of that ball is 171 feet a second. “But Louey did not take into account air pressure. Again, if a man can serve a ball from a heiglil. of Bft bin over a 3tt net, Hie result (inathematically calculated) would nc over 700 feet a second, which, as Euclid would have observed, is absurd. Mechanical tests will always countervail theories, and there is nothing (according to (he famous phrase) so fallacious as facts, except figures."