Plate, figure 1 showing mahogany, copper, and lead commutator by [William Thomson] Figure 1 showing a mahogany, copper, and lead commutator with bundles of copper wires soldered to it. Subject: Physics Published in Philosophical Transactions as 'The Bakerian lecture.-On the electro-dynamic qualities of metals'. Received and read by the Royal Society on 29 February 1856. [1856]