Gilt metal square; Paris, 19th century. Gilt metal. With workshop marks. Measurements: 11,2 x 15,5 cm (open). This piece belongs to the personal collection of Don Juan José Ontalva (Chinchón, 1930- Madrid, 2019), a famous watchmaker from Madrid, descendant of several family generations dedicated to the world of watches. During his career he achieved a high degree of precision and skill, becoming the master of other watchmakers. He is currently recognised for numerous works, including the commissioning and restoration of the Billeter astronomical clock, located in the Congreso de los Diputados (Congress of Deputies).