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 "father of seismology and magnetometry." In 1760 he was elected a Fellow of the Royal Society; two years later he became Woodwardian Professor of Geology at Cambridge. He applied statistics to astronomy and provided the earliest evidence that double stars and star clusters were physically bound, not optical illusions. He also proposed the existence of stellar bodies so massive that light could not escape them, a concept that prefigured black holes by nearly two centuries. He died on 21 April 1793, his name largely forgotten until the twentieth century rediscovered what he had