"Phil. The NT is a little different because we are closing our feet, but we don't close our feet very often when we dance. The heal does come up off the floor more on the second step when our weight is over the ball. I think I should have said there is no leg rise on the second step and not foot rise. The point is we are up at the end of one and any further rise is through body swing and not from straightening the knee on the second step."
Actually it is not a function of foot closure, but of the desired action for the person on the inside of the turn. If that person is going to do a lady's heel turn (foxtrot natural turn) then the leg will already be essentially straight during step two, as the rise must be completed on step 1. But for waltz rise, the leg remains more flexed as in step two and straightens during step two.
This gets somewhat confusing in that the legs may still be straight in the waltz action when the feet are apart, it is having the leg more or less straight when the body is over that foot that develops later in the case of waltz rise than it does in foxtrot rise.
One thing the book does not handle so well is that there are really at least three kinds of rise, which it attempts to reduce to two: the foot closure waltz, the open turn, and the heel turn.
The book would give the rise for an open turn in foxtrot as the same as for a lady's heel turn, which abstracts out a critical difference. This may go back to what was said the other day about the book rise and fall being primarily foot action, with the inclusion of body action the result of an incomplete revision. And of course there is also the man's heel turn and heel pull where there is not rise until the second step.