These strokes are no longer seen, of course, because of the limitation on ball-to-ball cannons, and the rule re touching balls.
At one time the rules stated that, if the cue-ball was touching an object ball, the player had to play at the ball which the cue-ball was not touching, or he had to play at a cushion before striking an object ball. This rule was not in force for very long, but for a time enabled some players to make very big breaks. As with all repetition strokes of this nature, after a time a groove forms in the cloth and the balls rest quite firmly in small indentations. For this reason, after a time a rocker cannon will leave the cue-ball touching the object ball (the one away from the cushion) The touching balls rule killed the rocker cannon but not before Willie Cook had made some very big breaks including a run of 400 rockers in a break of 1000 unfinished.
Considerably more difficult than the Rocker. The cue-ball is played delicately across the face of both object ball, first from one side, and then the other. Tom Reece once made 40 consecutive pendulums.
In 1891, Tom Taylor got the balls jammed in a corner pocket and scored 729 cannons in a break of 1467. The best known use of the jam was by Frank Ives in his famous match with John Roberts in 1893.(BQR. July '94.P10.) It is sometimes possible to get the position by accident. I have done this several times. In a Mini-Prix at Exeter a few years ago playing against Robby Foldvari, we both had the jam position in following visits but could manage no more than forty or so cannons between us. For two players to have the position in turn must be very unusual indeed.
Talking of Jams and Anchors reminds me of a game I played with Robby Foldvari in the Exeter Mini-Prix of November 13th, 1988.1 had started quite well with a fifty break. Robby missed and after a shot or two I played a drop cannon which left the balls quite near to the top left pocket.1 played a cannon which should have brought the white back across the table near to the spot and leave an easy pot red. That was the theory. In practice I made a total hash tangling with the pocket jaws and leaving the object balls over the lip of the pocket. One more shot fluked the Jam position. I made some twenty or so cannons before my really delicate touch sank the white leaving the red on the lower jaw and my cue ball very close. I tried to make a very gentle in-off to leave the red right over the pocket for, hopefully a few more strokes. I played the red much too thickly and, would you believe it, both balls jammed in the pocket opening. Foldvari, in hand, played a great drag stroke up the table, made the cannon, and had himself the Jam position - in one! He did not make very many cannons but there must be something unique about players both getting the position in following visits. (Snooker Scene: January 1989, P26) I also remember that game for the fact that, very soon after the incident described, Robby got the balls into the,:"Postman's Knock," position and made a break of 306.