Hop back in time and visit the Ri froggery.
How do you measure electricity before you’ve invented the voltammeter? This was the problem facing Michael Faraday and Humphry Davy, working on early experiments with electricity in the labs of the Royal Institution.
The solution was to use frogs. Luigi Galvani had famously discovered that passing a current through a frog’s leg muscles would cause them to twitch. For a long time, this was the only reliable and economical way of testing whether electric current was flowing, so the Ri kept an active froggery, jumping with live frogs. These frogs, unfortunately, reached an abrupt end when their services were required for an experiment.
Fortunately, it didn’t take long for technology to catch up, and soon the frogs were replaced with something a little more humane.