Andre Blondel

Andre Blondel was a French engineer and physicist, born August 28, 1863 in Chaumont and active for most of his career in Paris, where he worked on the instruments and theory that power engineers needed to understand alternating current. He invented the electromechanical oscillograph, an instrument for recording rapidly changing electrical signals, and his improved bifilar and soft-iron versions won the grand prize at the 1904 St. Louis Exposition and remained the standard tool for recording high-speed electrical phenomena for more than forty years. In 1899 he published the basic theory of the two armature reactions, direct and transverse, in alternating-current generators, work that became part of the standard analysis engineers used to design and couple synchronous machines. He contributed to one of the era's largest long-distance power transmission projects in 1909, which carried some 300,000 horsepower of electricity from the Genissiat dam to Paris over more than 350 kilometers of 120,000-volt polyphase line. Blondel also founded much of the vocabulary of photometry, proposing the lumen and related units in 1894 and later coining the phot and the stilb, and was elected to the French Academy of Sciences in 1913 and awarded the Faraday Medal in 1937.