John Theophilus Desaguliers (12.03.1683-29.02.1744) was an English natural philosopher and a Fellow of the Royal Society (1714). He was born in La Rochelle (France). In 1685 he moved to England. He graduated from the University of Oxford (1709), where he also worked.
His research was in the field of optics, mechanics, electricity and heat. He continued S. Gray's experiments on electrical phenomena and introduced the concepts of a conductor and a non-conductor of electricity and the term “conductor” (1742). He tried to prove experimentally the relation between kinetic energy and speed. In 1718 he introduced a safety valve into Papin's steam boiler. He played an important part in spreading Newton's teaching in Europe. He invented the planetarium.
A member of the Paris Academy of Sciences. The Copley Medal (three times).