A much easier way of accomplishing what you are trying to do is use the expression editor . . . . it will be your friend if you learn it . . . . you will want to use joints to control the tail, if you are doing animation . . . . this is how I would do it . . .
Create a group of joints, for simplicity, we will say joint1, joint2, etc.
joint2.rotateY = joint1.rotateY *1.1;
joint3.rotateY = joint2.rotateY *1.1;
joint4.rotateY = joint3.rotateY *1.1;
joint5.rotateY = joint4.rotateY *1.1;
So each joint rotates a little more than the previous. When you rotate joint1, it rotates all the other joints via the MEL code.
If you open up the expression editor in the file I have attached and select joint2, then look at "rotateY", you will see the code.
This code is MUCH simpler that whoever-it-was that was trying to write a tutorial . . . and simpler is better and easier to tweak if you need different results . . .
"The Sage as an Astronomer: If you still see the stars as something above you, you lack the eye of knowledge." Friedrich Nietzsche