Édouard Branly

Édouard Eugène Désiré Branly (23 October 1844 to 24 March 1940) was a French physicist and inventor known for his early involvement in wireless telegraphy and his invention of the coherer in 1890. The coherer, which grew out of experiments with tubes of metal filings such as those reported by Temistocle Calzecchi-Onesti in 1884, was the first widely used detector for radio communication: iron filings in an insulating tube between two electrodes conduct current under an applied electrical signal because the thin oxide layers covering the filings break down, latching the device into a low-resistance state until it is tapped. In 1890 Branly demonstrated what he later called the radio-conductor, which Oliver Lodge named the coherer in 1893, the first sensitive device for detecting radio waves. Lodge made it a practical receiver by adding a decoherer, Guglielmo Marconi developed it further, and it remained in widespread use for about ten years until crystal detectors replaced it about 1907. Branly died in 1940, his funeral was held at the Notre-Dame cathedral in Paris with the president of France, Albert Lebrun, present, and he was interred in Père Lachaise Cemetery.