The question is sometimes asked by beginners at billiards: How can I recognise the half-ball stroke?
Various answers have been supplied to this question and angle-sighting appliances have even been devised and supplied with the view of familiarizing the eye of the beginner with the half-ball throw-off.
To know that the half-ball angle is one of 35 degrees at the edge of the object ball and of (apparently) 45 from its centre may be a good thing and some useful practice may be obtained by the use of an angle-sighter in conjunction with a captive ball device. But the best training for the eye, after all, is to be found in the practice of fixed positioned half-ball shots, of which there are quite a number on the billiard table.
From the pyramid, centre, billiard, and baulk spots alone excellent half-ball practice is to be obtained, and we should advise some such course of practice as the following:—
(1) Place the red ball on the pyramid spot and the cue ball on an end baulk spot. This is a half-ball shot to the top pocket on the opposite side of the table and a half-ball cannon on to a ball placed well along an imaginary line from the red ball to the pocket.
(2) Place the red ball on the spot at the centre of the table and the cue ball four inches away from the end spot of baulk and towards its centre. This is a half-ball shot to the top pocket on the same side of the table and a half-ball cannon on to a ball placed well along an imaginary line from the red ball to the pocket. The cue ball must, however, be hit above the centre and the cue must be held lightly and sent nicely forward.
(3) Place the red ball at a point 24 inches above the centre baulk spot and the cue ball on an end baulk spot.
This is a half-ball stroke into either middle pocket, but again the cue must be held lightly.
(4) Place the red ball on the centre baulk spot and the cue ball exactly behind on the circumference of the half circle.
This is a half-ball stroke with too and light handling into either middle pocket, or from an end baulk spot, with similar treatment, into a baulk corner pocket.
[In Nos.1, 2, and 3 the object ball should be played with strength bringing it nicely placed for a middle pocket.]
A useful hint may be given concerning two classes of shots, which are radically distinct from each other and which have, nevertheless, one thing in common. They are almost invariably taken by beginners too fine in the one case and too full in the other. The shots are run-through follows and pots, and what has been said applies more particularly to pots when the object ball is fairly near a corner pocket and to run-throughs when the pocket or cannon ball is some distance beyond the object ball.
In the former case aim taken midway between the edge and centre of the object ball only deflects such ball a couple of inches at the end of a foot run whereas the same contact in a follow-through would deflect the cue ball a couple of feet in the length of the table. A pot, with the object ball near to a corner pocket looks more direct than it really is and at a distance less direct. Inversely a follow-through with the cannon ball near at hand looks less direct than it is and at a distance it looks more direct.
The safeguard with near pots and long follow-throughs is to aim finer in the one case and fuller in the other, and great assistance is to be gained by gauging the direction to be taken by the object ball in pot strokes and by the cue ball in run-throughs as though the objective point were about a foot beyond the cue ball.
This would mean carrying the eye beyond the pocket in some cases, but it is an excellent plan to adopt as it at once reveals the fact that the course to be taken by the red ball if the intervening shoulder of the pocket is to be avoided will have to be considerably wider than appears to be the case. This applies, of course, more to corner than it does to middle pockets.
There is a surprising affinity amongst the various strokes on the billiard table either at long, medium, or close range, and this applies to cannons as much as it does to in-offs and pots, and to nursery cannons as much as it does to round the table cannons. In cannon play, however, there are three balls to be moved instead of two, as, in pocket play, and this increases the difficulty of the cannon position game by at least the fifty per cent. represented.
It has been customary in published works upon the game of billiards to represent the cannon stroke as vastly more easy than the pocket stroke and this may be true of the stroke per se. Three billiard balls measure in their combined diameter 6¼ inches, and as the cannon ball can be hit on either of its two sides, as well as full, there is certainly more margin for error than in pocket play, as a plainly struck ball whose centre reached a 3 5/8 pocket, two inches from the centre of such pocket would obviously be prevented by the shoulder from entering.
We have thus in a cannon ball a target apparently more favourable than a pocket, but this apparent advantage is reduced when it is recollected that a centrally-struck ball often enters a pocket after actual contact with its shoulder and that, by the use of side a ball may be made to enter a pocket even when it strikes the cushion a few inches below such pocket.
Our immediate object, however, is to point out that merely making a given cannon in billiards is a very small part of the purpose of the shot. The aim should always be taken, not merely as from ball to ball, but as from (1) ball to centre of ball, (2) ball to inner edge of ball, and (3) ball to outer edge of ball.
This sort of cannon play requires even greater accuracy of aim than pocket play, but it can be done with a little thought and attention, and there are few things more paying in billiards.