Curious instrument of the harmonium or accordion family that arose in 1837. Its mechanism hides inside a box that would never be opened in order to leave doubts regarding the means of sound production. It belonged to the French musician, composer and cello professor, Jean Louis Olivier Cossoul (1800-1893), father of Guilherme Cossoul (1828-1880), musician and founder of the Lisbon Volunteer Firefighters [Bombeiros Voluntários de Lisboa].