Billiards

by William Broadfoot

The consideration of regulated screw leads to the insertion of fig. 5, in which a class of strokes of common enough occurrence, but little relished by players whether amateur or professional, is illustrated. They are intermediate between the path of a forcing stroke and that of the right-angle screw. Now the latter, though decidedly difficult when the balls are far apart, say 2 ft. or so, yet admits of some certainty in playing, for it represents about the maximum of most men’s power; but the intermediate strokes, though they require less execution, are yet oftener missed, because the player has no definite measure of them, no guide or clue to which he can trust.

If the paths represented from ball 1 to ball 2 and then to ball 3 be those of a hard forcing stroke, and the paths 1 to 2 and 2 to 3A those of a right-angle screw, the strokes referred to lie between the two, and may be represented by the dotted lines from 2 to 3B, 3C, &c. The balls may be set up as shown; ball 1 on the right spot of the Ｄ; ball 2 at the same distance from the side cushion line and opposite the centre of the middle pocket; ball 3 anywhere between the pocket and the limit of a forcing stroke in the positions marked 3B, 3C, &c.; or ball 1 may be advanced nearer to ball 2, in which case the strokes are easier. In either case practice at these intermediate angles will not have been thrown away if the remarks and advice respecting screw be appreciated and followed. Do not forget that when played with strength ball 1 will pass beyond ball 2 before the screw takes effect.

In practising the straight screw back it is advantageous to keep the cue exactly in position after the stroke, which, if true, will result in bringing ball 1 back to the tip. Also the behaviour of ball 2 after each stroke should be noted, in order that when playing in a game its position may be approximately foreseen. Always chalk the cue before attempting a screw.

Rotation round a horizontal axis having been considered, it is necessary now to examine side, or rotation round a vertical axis. This is communicated by every stroke of the cue which is not delivered precisely on the vertical line H B (fig. 6), and is, as may readily be conceived, generally applied unintentionally. In fact, much of the preliminary practice has been recommended in order that the power of striking a ball without side might be acquired. Still, when intelligently used, side gives great additional scope to a player and will well repay attention and study. To discuss right side and left side separately is unnecessary, for the one is simply and solely the reverse of the other.

Side, or rotation round the vertical axis, does not convey to a ball a movement of displacement or translation; on the contrary, its tendency is to bring the ball to rest, precisely as a top when thrown with heavy spin at first gyrates or travels a little, but soon comes to rest, or sleeps, whilst revolving at a great rate. Hence it follows that some compensating strength has to be used when playing with side.

Now, the student cannot have got so far, supposing that the various strokes have been practised, without having acquired some knowledge of the effect of side. He has learnt, for example, that the more out of the centre his ball was struck, the more did the angle of reflexion vary from the angle of incidence; if struck on one side, the angle of reflexion was enlarged; if struck on the other side, it was diminished. Side also makes some, though less evident, modification in the angle of deviation after impact with another ball. The proper mode of communicating side to a ball by means of a cue must now be considered, G H D B is a ball standing on the table T T; H B is its vertical axis, C its centre, E and F represent the cue-tips at the moment of striking the ball: E for right side, or side which tends to take the ball towards the right, and F for left side, which will carry the ball to the left. It will be observed that the cue is delivered on the central horizontal line, for on it the maximum of rotation round the axis H B can be given; in other words, the height of the stroke is precisely the same as that for a plain or true centre stroke, and is equal to half the height of the ball.

Fig. 6

The next point is the proper alignment of the cue. In a plain stroke it has been shown that the path of ball 1 previous to impact is the prolongation of the line of the cue’s axis. For a side stroke, the point of aim being the same, the only difference is that ball 1 must be struck on the side instead of in the centre. Hence, to preserve the same path, the cue’s axis must be parallel to that in the plain stroke and distant from it in proportion to the amount of side to be given.

Fig. 7 illustrates the chief points connected with side strokes, and admits of comparison between them and an ordinary plain stroke. Ball 1 played half-ball plain on ball 2 travels the path shown by the continuous line 1 1′ 1″ and 1‴, and the angle at which it comes off the cushion is nearly equal to that of approach. The position of the cue is the central one on the prolongation of the path 1 1′. The same stroke played with right side is thus effected: the cue is moved to the right, its new axis being parallel to the original axis. The stroke is delivered in precisely the same way and in the same direction, save that the point of ball 1 struck by the cue is to the right of the centre. Ball 1, if struck with the strength of a full No. 1 or more, travels practically the same path until it strikes ball 2, after which it deviates slightly to the right, following the path marked by dot and dash alternately, and reaches the cushion at R, whence it flies off at an enlarged angle in the direction of R′. Right side for the stroke figured increases the velocity of ball 1 after impact with the cushion, from which it shoots perceptibly faster than does a ball plainly played. Hence, this side is termed direct, being given in the direction that the ball is intended to travel.