[Yoda]

My next question was going to be, can I substitute perpendicular for vertical?

thanks everybody- I am not giving up on this hinge concept.

No problem, Jerry.

In fact, when I choose to discuss these things with students . . .

I use the term perpendicular (relationship of the Flat Left Wrist to one of the Three Associated Planes) all the time. But, only after I've used the term Vertical, and then only because students relate more easily to perpendicular than to vertical. And then I explain the difference.

Now, why all the bother?

Assuming an intelligent golfer who wants to know -- indeed needs to know -- the answer is simple . . .

In the constructive vocabularly of The Golfing Machine, the term Perpendicular relates to the Wrists' overall up-and-down plane of Motion (Level, Cocked and Uncocked). The term Vertical relates to the mid-condition of the side-to-side Rotational Motion (Vertical, Turned and Rolled).

Then, answering your question here, when we relate the Left Wrist to a given Plane of Motion -- Horizontal, Vertical or Angled -- we can do so in its Rotational frame of reference. Namely, Vertical, i.e., neither Turned nor Rolled.

Hence, Vertical to the Ground (a Horizontal Plane) describes the mid-condition of a Rotational Motion, not Level, the mid-condition of a Perpendicular Motion.

Screwy stuff, I know. But when you're a teacher helping your student get results . . .

Precision matters.

The Wrists have Three Planes of Motion (Horizontal, Perpendicuar and Rotational). Within these are three sets of three -- Flat, Bent and Arched; Level, Cocked and Uncocked; Vertical, Turned and Rolled -- with the first term indicating the mid-condition within each Plane.

Most of the time, except as he needs to on this particular day, the student never knows.

But, the teacher knows.

And, so does the Ball.

That's a good thing!