Charles Wheatstone

Sir Charles Wheatstone (; 6 February 1802 – 19 October 1875) was an English physicist and inventor best known for his contributions to the development of the Wheatstone bridge, originally invented by Samuel Hunter Christie, which is used to measure an unknown electrical resistance, and as a major figure in the development of telegraphy. His other contributions include the English concertina, the stereoscope (a device for displaying three-dimensional images) and the Playfair cipher (an encryption technique). Provided by Wikipedia