Stephen Butterworth

Stephen Butterworth (1885–1958) was a British physicist who invented the Butterworth filter, a class of electrical circuits that are used to separate different frequencies of electrical signals. Stephen Butterworth was born on 11 August 1885 in Rochdale, Lancashire, England (a town located about 10 miles north of the city of Manchester). He was the son of Alexander Butterworth, a postman, and Elizabeth (maiden name unknown). He was the second of four children. In 1904, he entered the University of Manchester, from which he received, in 1907, both a Bachelor of Science degree in physics (first class) and a teacher's certificate (first class). In 1908 he received a Master of Science degree in physics. For the next 11 years he was a physics lecturer at the Manchester Municipal College of Technology. He subsequently worked for several years at the National Physical Laboratory, where he did theoretical and experimental work for the determination of standards of electrical inductance. In 1921 he joined the Admiralty's Research Laboratory. Unfortunately, the classified nature of his work prohibited the publication of much of his research there. Nevertheless, it is known that he worked in a wide range of fields. For example, he determined the electromagnetic field around submarine cables carrying alternating current, and he investigated underwater explosions and the stability of torpedoes. In 1939, he was a "Principal Scientific Officer" at the Admiralty Research Laboratory in the Admiralty's Scientific Research and Experiment Department. During World War II, he investigated both magnetic mines and the degaussing of ships (as a means of protecting them from magnetic mines). He was a first-rate applied mathematician. He often solved problems that others had regarded as insoluble. For his successes, he employed judicious approximations, penetrating physical insight, ingenious experiments, and skilful use of models. He was a quiet and unassuming man. Nevertheless, his knowledge and advice were widely sought and readily offered. He was respected by his colleagues and revered by his subordinates. In 1942 he was awarded the Order of the British Empire. In 1945 he retired from the Admiralty Research Laboratory. He died on 28 October 1958 at his home in Cowes on the Isle of Wight, England at the age of 73.