The Dulcian was used well into the 18th Century, but was slowly replaced by the Baroque and Classical bassoons. Two developments occurred: that of the German and French bassoons. Each model of bassoon gradually added more keys and changed details in the construction of the joints to stabilize the pitches of the instrument, and by the time Mozart wrote the Concerto in B-flat that changed the Bassoon’s place in the musical world, the German bassoon included at least 7 keys