Left means left of centre from line of aim.
The cue-ball is that with which the play is made.
The object-ball is the first ball struck by the cue-ball.
The carom-ball is the second ball struck by the cue-ball, completing the carom.
It is first necessary to master the centre-stroke, which is accomplished by delivering the cue at the point g, the line g, e, a, being the centre diameter of the ball.
The centre stroke imparts to the ball a natural impelling force where the strength of stroke is not in excess of “ordinary” (see Plate I). This stroke should always be used unless the player has a reason for a different delivery. Any divergence from the centre produces an effect on the ball in excess of the natural, and when applied in the smallest degree the result should be fully understood.
A centre stroke, with exceeding strength, produces an effect herein explained:
A centre stroke, slow or medium, will cause the cue-ball to rotate the instant of delivery, but in excess of medium the ball will slide a distance over the cloth before rotating, that distance being governed by the strength of stroke, and when thus sliding should contact be had with an object ball, at the slightest variation from its centre, right or left, the cue-ball will perform a right angle to either side, and the object-ball, taking up the impelling force, continues the direct right line of the cue-ball.
The Follow-Stroke.
By viewing the diagram in such way as will bring the explanation under letter A into a proper reading position, the follow shot is seen. For this stroke the cue is delivered ½ above centre, imparting two forces to the ball: impelling it forward in direction of arrow a and rotating in direction of arrow b, the entire force of the blow converging to centre of motion e. With this stroke the cue-ball, after striking the object-ball full, follows directly in its path. At the instant of impact with an object-ball, the cue-ball will, if struck with great strength, apparently stand still through the resistance of opposite forces caused by contact, but the rotating power overcoming the repelling tendency of the concussion, carries it forward on its original path.