A Knob of Butter

In 1991 Jimmy Hernandez asked me how big a knob is (in relation to a microwave meal he was preparing). I opined that it was probably an isosceles right-angled tetrahedron whose adjacent is equal to half the height of the block of butter. I was wrong, and I owe Jimmy an apology for my amateur grasp of geometry at that time. I do hope it didn’t spoil his lunch.

I also wish to apologise to the Earth edition of The Hitchhiker's Guide to the Galaxy, who in 2003 accepted my inaccurate description of a knob of butter into their lexicon.

A knob of butter is, in fact, a trirectangular tetrahedron with an equilateral base whose edge lengths bounding the trihedral angle equal half the height of the butter*.

I hope that clears everything up.

This artwork is available on all the usual gear.

*Note: This is an international unit of measure. Americans may need to subtract an arbitrary number and divide by zero.