The case and the canon in laboratory life

This is a study of William Thomson (Lord Kelvin) focusing on the laboratory work that he carried out in electricity and magnetism early in his career, while reflecting on Faraday’s “lines of force”. During those years Thomson, who had been trained in Cambridge as a mathematician, was turning himself into an experimental physicist with a predilection for scientific instruments and a bent for industrial applications. The paper shows that, when trying to understand Thomson’s ambitions and demeanour, it would be pointless to put under separate rubrics what actually merged in his daily life: his passion for teaching physics and attracting crowds of students to his classes with spectacular demonstrations; his curiosity for a field theory able to explain the puzzling variety of electromagnetic phenomena with mathematical precision; his fascination with instruments and machines; and his inclination to pursue the kind of social, upward mobility that was celebrated in Victorian Britain as a key promise of industrial society