When Georg Ohm was experimenting with electricity, he knew about the researches of Volta, Ampere, and Galvani. He knew the history of electricity back to Franklin and before. He knew that there was potential, and flow, and limits to the flow that could be detected qualitively.

But no one had standardized the units of measure, and no one had determined the relationship of those 3 quantities. Using the most primitive of handmade instruments, he set about doing so.

Ohm used a torsion galvanometer of his own design and fabrication, and I’ve looked at the diagrams. I could reproduce that, and I may still do so, but I think my first big project in this series will be to produce a more robust follow-on instrument, based on d’Arsenval’s meters.