According to the Internet source given below, François Cosset was a French composer. Born in Picardy around 1610, Cosset first worked in Saint-Quentin and in Laon before becoming director of music at Notre-Dame Cathedral in Reims. Apparently without leaving this position, he took on a like post at Notre-Dame in Paris, succeeding Jean Veillot in 1643. However, following criticism from Queen Anne of Austria concerning two flawed performances of a Te Deum in 1646, he returned to Reims, as indicated by a deed of 1650. Cosset wrote eight masses in 4, 5 and 6 parts published as of 1649 by Robert III Ballard; the last mass was
published posthumously in 1673 under the title Missa sex vocum super flumina Babylonis. Few of these polyphonic masses were published after this date.