How did Thomas Johann Seebeck discover the thermoelectric effect?

In 1821, German physicist Thomas Johann Seebeck discovered the thermoelectric effect while conducting experiments on the magnetizability of various metals.12

He observed that when two dissimilar conductors—such as a copper strip and a bismuth strip—were joined to form a closed circuit, heating one of the junctions induced an electric current to flow through the circuit as long as a temperature difference existed. Seebeck initially identified this phenomenon by observing the deflection of a compass needle placed near the circuit, which led him to mistakenly interpret the discovery as a magnetic effect caused by temperature differences.132

His experiments revealed that this effect occurred with any pair of metals, and he found that even the heat from a human hand applied to one junction was sufficient to produce a measurable current. While Seebeck successfully categorized various materials into a thermoelectric series, the practical significance of his discovery as a method for generating electricity was not fully recognized at the time due to his initial misinterpretation.12