How it works
From the System Library: the source's numbers, checked in this game's physics but not reviewed by a coach.
Short-long-short without side, worked by multiplying: Aim = Start × Arrival. The start is on the long rail, the aim on the short rail at that end, the arrival on the far short rail.
Each rail counts its own way: the start half a point a diamond, the aim 10 a diamond, the arrival from 10 down to 4, one every two thirds of a diamond — 7 at the middle, which gives the system its name.
Reading the numbers
Start On the long rail behind the cue ball, along the line it leaves the red on: 1.5 at the first diamond from the aim's short rail, half a point a diamond to 5 in the far corner.
Aim On the first cushion, the short rail at the start's end: 0 at the corner by the start rail, 10 a diamond to 40 in the other corner.
Arrival On the third cushion, the far short rail: 10 at the start rail's corner, one less every two thirds of a diamond — 7 at the middle — to 4 in the other corner.
Step by step
- Choose the arrival on the far short rail: where the cue ball must come to make the second object ball.
- Read the start from the line the cue ball leaves the red on, traced back to the long rail.
- Aim = Start × Arrival. Start 4 to arrive at the middle, 7: aim at 28.
- Re-read the start along the new line, work it once more, then add the table correction.
The stroke
No side, a little above centre, a soft follow stroke.