ABSTRACT
Faraday’s handwritten notebooks, which in printed transcript run to seven volumes, have long been of interest to historians and philosophers of science because of the extraordinarily direct insight they give into the way his thinking developed ‘in real time’. Laboratory notebooks often contained sketch drawings of apparatus. In the experiment he carried out on 30 May 1831 his aim was to see whether an electric current could be induced in a wire by subjecting it to a temperature gradient. Amongst the myriad phenomena that Faraday can be credited with discovering, that of semiconductivity is not mentioned very often. After discovering electromagnetic induction, Faraday devised many other arrangements of coils carrying current, but then took the further imaginative step of moving a bar magnet through a coil of wire, whereat a current also flowed. Delicate experiments with a galvanometer could be disturbed by small magnetic fields induced through surprising sources: but there was always an answer: 15766.
