Today is Pi Day apparently. I have never really understood this for three reasons: (a) Pi is an irrational number and therefore is not 3.14 but rather 3.14159235… ad infinitum; (b) because of point (a) we were always taught to use 22/7 for the value of Pi at school in the days of mental mathematics; and (c) in the vast majority of the world where the date format is dd-mmm-yyyy not mm-dd-yy, the fractional number for Pi of 22/7 would be the 22nd day in July Therefore that would make much more sense to me to be Pi Day, but I guess pinning it to 14th of March just proves how much sway the US has in the world!

That being said, I looked to see if I had any pi-related imagery (or even pie-related, for comic effect) but as I didn’t I decided to use this one I took several years go which demonstrates the relationship between the radius of a circle and its circumference. If the length of the wire with the sparking basket is r then the circumference of the circle being traced is 2πr, although as you can see here it’s difficult to keep that thing spinning at a fixed distance from the camera!

~Richard