You started it Kid, now I'm going to slow things down a bit, so you can follow along, and maybe understand something.
The point of the cushions are at 1 7/16" of an inch high at ball contact. The object balls are 2 1/4" round, that makes it 1 1/8" of an inch to the dead center of the object ball, including the cue ball. Now, if you subtract the difference between the two, the center of the object balls is 5/16" of an inch below the point of the cushion. So, you asked the question, "How come the balls are jumping off my rails?" So, through a process of elimination, we rule out all the other possible reasons for the balls to be jumping off your rails, leaving only humidity as the reason.
First let me explain what happens when you bank the cue ball into the cushions on a normal table, in normal conditions. If you play draw english on the cue ball, it's spinning back-wards when it comes into contact with the cushion, meaning it's trying to dig under the point of the cushion, and in fact, the backward spin is trying to lift up the point of the cushion at contact. As the cue ball comes off the rail, it don't have to slide on the cloth to change direction of the spin because it's already spinning in the direction in which its traveling. Try that on your table just once. Shoot the cue ball straight into the cushion where it jumps off with draw english, and I guarantee it WON"T jump!
Next, a cue ball hit with center english is not spinning at all, it's actually sliding on the cloth without any spinning movement at all. When the cue ball slides into the cushion, it compresses the cushion rubber straight back, and rebounds off, UNLESS...the cushion rubber is lower than 1 7/16" of an inch, in which in your case, it's not! Now, a center hit cue ball, if it rolls forward before it hits the cushion, has forward spin on it because its no longer sliding.
Then, finally, top spin. With top spin, like draw english, you can change the angle of deflection coming off a cushion because as the cue ball is rebounding off the cushion, its still spinning in a forward direction, normally when a cue ball comes off a cushion, even though its traveling away from the cushion, its still spinning in the directions of the cushion until it reverses direction caused by the friction of contact between the cue ball and the cloth. This is why cleaning and waxing the balls is so important, because it helps reduce the friction build up caused by the surface of the balls, thus giving you better breaks and an increased ability to apply english/spin with the cue ball. But, in order to reduce the friction of the surface of the balls you also have to keep the surface in which the balls roll clean as well, or you're just wasting your time cleaning the balls, they're just going to pick up the dirt from the cloth right away, and go back to playing the same.
Now lets add some humidity to the table. Humidity is moisture. Moisture on the cloth creates a tremendous amount of "Friction" to the surface of the cloth and as the balls roll around on the cloth, they pick up the moisture as well on the surface of the balls. Combine humidity with dirt, and you have balls clinging on top of each other if they come in contact just right, usually that happens when the object ball is rolling in a forward direction and comes in contact with another object ball sitting still. The ball with forward momentum tries to climb up on the second ball, causing what is referred to as "Cling" and tries to hold onto it for a split second, screwing up the shot you just tried making.
Now, with the addition of humidity to the cloth and balls, when the cue ball has a humid surface, and the cloth has a humid surface, the cue ball when it comes into contact with the cushion with forward english, instead of sliding off the cushion, it actually with its forward momentum tries to climb "UP" the point of the cushion, causing it to lift off the playing surface as it tries to climb up the point of the cushion. Now, as it climbs the cushion and compresses the rail rubber at the same time, the rubber decompresses and pushes the cue ball backward but in an upward rebounding angle because the cue ball is no longer touching the playing surface of the slate/cloth
You have one of three options to stop the cue ball from jumping off the rails.
1: Remove/lower the humidity from the air in the room the table is in.
2: Dry out the cloth with heat, which will help keep the surface of the balls dry.
3: Clean the cloth and wax the balls daily, or at lease every time before you plan on playing.
At the very least, throw a heating blanket on the slate, and let it warm up the table for a few hours before you decide to start playing, that'll help dry out the cloth. Circulate the air in the room, even if its just with fans, that also helps to evaporate humidity.
Glen
