Cool Faulk.  I still think spine testers were developed first for testing the stiffness of hickory violen bows.  Long before they were used for arrow shafts.  Someone just came up with the math to relate it to bow poundage.  Who ever he or she was, was a smart person. I'd be willing to bet the theory is a hundred years old or more(probably much more)        Thanks...Van

That should be right on.