J. J. Thomson was an influential physicist, both for his own research, for which he won the Nobel Prize, and for the work he did to establish the Cavendish Laboratory at Cambridge as a major research school. He began his career studying the theory of electricity which built on the work of James Clerk Maxwell. In 1897 he discovered the particle later named the electron, the existence of which was first announced at a Friday Evening Discourse at the Royal Institution (Ri). Thereafter he worked on developing a theory of matter. Thomson won the Nobel Prize in 1906 for his studies of electrical conduction through gases, which he began following Wilhelm Roentgen's discovery of X-rays in 1895. Thomson was appointed a Professor of the Royal Institution in 1905 and remained associated with the Ri for the rest of his life.