Posted by js on November 20, 2003 at 00:03:01:
In Reply to: Flat Chin? posted by dude on November 19, 2003 at 23:09:03:
The confusion arises from an attempt to describe something with words rather than pictures - or better yet, in person.
My best guess is that the book you've read warns against "bunching" the chin (still words...still inadequate communication).
Locate an old copy of Art of Brass Playing - Philip Farcas, and look at archival Chicago Symphony Orchestra members' embouchure pictures.