Stress

Everett Garrison, in his book "A masters Guide to Building a Bamboo Fly Rod" used his knowledge as a structural engineer to mathematical produce stress curves.
Basically a stress graph shows the rod maker how close a rod is to breaking, with the length of line and weight specified.
It also shows the characteristics of the rod; fast, slow, parabolic etc.
Garrison believed 200,000 ounces per square inch was a safe level.Stress graphs show mathematically the given stresses at a location on the rod. When reading a stress graph the X axis is rod length, with the tip on the left and the handle on the right. The Y-axis is ounces per square inch a stress measurement.The higher the reading on the stress graph the more the rod will bend at this point.

Most of the stress is at the tip,this would make a tip action rod

A parabolic action there is more stress in the butt section.

A progressive taper,almost even stress.