Green's Functions

Green's Mill was run by the mathematician George Green. I finally understood Green's Theorem after 30 years http://wigtonphysics.blogspot.com/2018/01/greens-theorem.html and so was keen to go back to the mill. I wanted to see the Local Heroes film by Adam Hart-Davies which uses clockwork toys to explain aspects of the theorem. I looked for it on the Internet when I was trying to understand the theorem but couldn't find it. They still have it playing. But they also have this film about Green's Functions https://www.youtube.com/watch?v=ji-i6XCkgC0. No wonder I cam across them when I was working on perturbation theory in quantum mechanics. If you disturb a linear system in one place, they allow you to calculate the effect time T later in another place.