Probably few billiard players have eyes that are in exact focus and it is necessary that due allowance should be made for this fact in striking. The first essential is that the face should be at right angles with the cue—in other words, that the eyes should look square and not in the least degree sideways at the object ball. Players who do not observe this fundamental requirement can never aim straight, even if possessing normal eyes. This can be proved in a moment. Place a ball on the table and hold your hand upright in front of your face. Now close the eyes alternately so that the ball first appears at one side of the hand and then at the other; and in both cases equally.
Next turn the face a little to one side without moving the hand, and argument on the point will be unnecessary, as the ball will appear quite wide on one side and will be obliterated by the hand on the other.
There are many players who strike with the sideways glance and a half-ball or other angle is consequently a different thing with them from what it is with other strikers.
Hence the difference of opinion as to angles that arise, as well as the unnecessary complications that are occasioned to the player himself. He will, for instance, have two distinct half-ball angles to deal with—one when looking square at the ball before getting down to the stroke, and the other when actually addressing the ball and looking at it sidewise.
But in this article I have to do with the striker whose face and arm are in proper alignment with the intended run of the cue ball, but whose eyes are not in perfect focus, and there is only one correct course for such a player to adopt.
He must always aim a trifle finer on one side of the object ball and a trifle fuller on the other. To ascertain on which side he is to do the one and on which side the other can be quickly ascertained. Let him place the red ball on the centre spot of the table and the cue ball to the left of the centre baulk spot with its edge in line with such spot.
Now let him aim at the left edge of the object ban and the red, if the aim be accurate, will disappear in the top right hand pocket If the cue ball were similarly placed on the right of the baulk central spot and accurate aim taken at the right side of the red ball the latter would disappear in the left top pocket.
The value of this experiment and practice will quickly be apparent If when aiming at one side of the red the object ball is almost invariably cut below the corner pocket, and when aiming on the other it is almost invariably cut above it, the conclusion may be accepted that one eye is somewhat at fault, and aim henceforth must be a trifle fuller or finer than hitherto according to which side of the object ball is aimed at. If on the other hand the object ball is driven as often as it is cut on both sides of the table, the cue delivery is defective and improvement and correction must be sought in this direction.
It may be thought that the error lies in the wrong cue alignment although the actual stroke may be delivered and finished in a perfectly straight line, but this is scarcely likely to be so. The cue, assuming that the forearm is hanging perpendicularly and that the eyes are square with the cue, will be guided by the eye, without conscious movement of the hand into the right alignment, and this again can be proved in an interesting way. Place two balls in the position in which a thick run-through cannon is required and take aim dead straight at the first. But when actually striking—and without shifting the aim in the slightest— glance at the second ball, instead of the first, and the run-through will be perfectly made. The same thing applies, of course, to run-throughs into pockets, and the reason is that with the movement of the eye the cue has become deflected in the exact proportion necessary for making the stroke.