John Michell

John Michell was born on 25 December 1724 in England and trained as both a natural philosopher and a clergyman, a combination that gave him the time and intellectual freedom to chase questions no one else was asking. In 1755, after the Lisbon earthquake, he became the first to propose that earthquakes travelled in waves and measured their velocity. He invented an apparatus to measure the Earth's mass — a device later used by Henry Cavendish to determine the gravitational constant — and published the first accurate statement of the law of magnetic force, work that later earned him the title "fa…