Just for the record, yes, you need both wires. That's true for ANY electrical circuit: it needs to be closed loop.

First: Please don't perpetuate the myth that blade grinders can scorch beans (or even warm them appreciably). That's nonsense.

Second: Zassenhaus!

This is so pickayunish that I hesitated to say it at all, but: Centigrade was replaced by Celsius in the late 1940s or so. Amazing how long these things stick around, eh? People still say "Palm Pilot" too...

A very minor point, but Tim Lindemann is not a glass blower, he is a lampworker or flameworker. There are major differences in the 2 arts, though of course both involve hot glass.

Nice lionfish in any case :-)