Sorry. I just popped back onto this thread from another one, saw what jpk had written, and without checking further back, assumed that he was trying to get away with Rush's little scam (sort of "Archimedean screwing" around with displacement). I'm afraid I knee-jerked. As I said, I was just waiting for someone to try to pull that one.

I'm try not be so precipitous in the future.

Don Firth