Chapter V

Fig. 6 ]

From the strokes recommended in Chapter III. for practice it will have been learnt that in a general way a ball played against a cushion will return therefrom, so that the angle of reflexion shall be nearly equal to the angle of incidence. A useful two-ball practice based on this is to place balls 1 and 2 on the table and endeavour to play on 2, having first struck a cushion. The difficulty is to determine the point on the cushion on which 1 must impinge so as to rebound on 2.

The solution is approximately:—From ball 1 let fall 1 A perpendicular to the cushion A C D; produce 1 A to B, making A B = 1 A. Join B with the centre of 2; where that line cuts the cushion at C is the point required. Play 1 so that it shall strike C and it will rebound on 2. Similarly, if the second ball occupy the position 2′ the line from B to its centre intersects the cushion at D; ball 1 played to touch the cushion at D will travel to 2′. In a game of course the cushion must not be marked, but in practice it will at first be found advantageous to mark the spot sufficiently to guide the stroke and educate the eye. This is easily done by placing a piece of chalk on the wooden frame of the cushion just behind the spot to be hit, thus doing away with the need of marking the cushion with chalk, which it is well to avoid. When it is necessary to mark the cloth of bed or cushion, pipeclay such as tailors use is preferable to chalk. Special attention is necessary to two facts: first, the angle of reflexion varies with the strength; that is, a soft stroke will come off very nearly at the same angle as that of incidence, whilst with a hard stroke there is a perceptible difference; second, the point on the cushion which should be hit must not be aimed at. This is merely a modification of what has already been explained with reference to the points of aim and of impact. Fig. 7 shows how very far a ball on the line 1 P played, _i.e._ aimed at P, is from hitting that point; instead of doing so it strikes the cushion at T; hence allowance must be made in aiming, the length allowed on the cushion diminishing as the angle approaches a right angle. When the stroke is at a right angle to the cushion the points P and T coincide and no allowance is required.

One reason why the angle of reflexion varies with the strength is that, on impact with the cushion, the ball, being harder than the rubber, indents it—makes a sort of cup, in fact, deeper as the stroke is stronger. Friction with the cloth of the cushion has also some effect on the angle, and there may be other causes at work; fortunately, it is probable that one to some extent counteracts another. This practice from a cushion is interesting as well as useful; at first the beginner will be satisfied if he hits ball 2 anywhere and anyhow; but soon he will be able to hit it on one side or the other, as he may wish, when the distance ball 1 has to travel is not very great. Hereafter both cannons and hazards will be mentioned, which must be played _bricole_, or off a cushion before ball 2 is struck, and the practice proposed will make their execution fairly easy and certain. We conclude this chapter, which has covered important ground, with four illustrations of the division of ball 2 at the moment of impact. A shows ball 1 applied to 2 for a quarter-ball stroke, B for a half-ball, C for a three-quarter-ball, and D for a full ball stroke; the phases varying between partial and total eclipse.

Fig. 7
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Fig. 8
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