 His next book, "Notes on recent researches in electricity and magnetism" (1893), built upon Maxwell's "Treatise upon electricity and magnetism", and was sometimes referred to as "the third volume of Maxwell".In it, Thomson emphasized physical methods and experimentation and included extensive figures and diagrams of apparatus, including a number for the passage of electricity through gases.His third book, "Elements of the mathematical theory of electricity and magnetism" (1895) was a readable introduction to a wide variety of subjects, and achieved considerable popularity as a textbook.