The tradition of Friday evening discourses at the Royal Institution was started by Michael Faraday in 1825. Since that time most major scientific figures have spoken in the famous Lecture Theatre at the heart of the Ri building at 21 Albemarle Street. Notable talks include Faraday announcing the existence of the technology of photography in 1839 and J.J. Thomson announcing the existence of the fundamental particle later called the electron in 1897.