Athletics of To-Day 1929

Throwing the Discus 295 distant from the centre of gravity. Consequently these missiles must always travel with an even centre and with no force reacting through their shape to make them eccentric in flight. The discus, on the contrary, is so shaped that it has every tendency towards eccentricity, and it must be thrown truly and made to spin fast if it is to travel gyroscopically fiat; and, of course, the more body extension force and arm swing, polished off with wrist-flick and finger-pull, that is put into the throw, the faster will the discus rotate. A strong throw without wrist-flick and finger-pull will not enable the discus to revolve fast enough round its centre of gravity, and consequently it will change its rate of rotation, and so wobble in flight, until its horizontal rotation fades right out and the discus rotates vertically. The following diagram (Fig. 42) shows three positions of a poorly thrown discus, with its centres of rotation along the line AB and not corresponding with the centre of gravity, which passes through the centre screw whereby the discus is fastened together. The constant changing of the centre of rotation and its non-coincidence with the centre of gravity make the FIG. 42 discus unstable in flight, and an undue amount of air resistance is created, whereas a discus correctly delivered at an angle of 30 degr es and given plenty of spin will cut through the air edge on and slightly up-tilted, so that the air is forced to bear a good deal of the weight of the missile. The thumb should be used to correct the angle of delivery, for if this be too high the discus will fly face on to the wind and lose distance. Points to note are : (r) The turn is smooth, like a waltz step, and must not be a jump round. (2) Let the arms hang out loosely when turning and keep the throwing arm back until it is ready to strike when the right shoulder is well forward.