Nocturnal dials tell time by the stars. This instrument replicates an original nocturnal dial created by Girolano della Volpaia in Florence in 1569, held in the Museo Galileo in Florence. It consists of three superimposed brass disks: an outermost disk of days, divided in 360 degrees, with months and zodiac signs; a middle disk divided into 24 hours with an indicator for "Media Nox"; and a top disk with 24 numbered teeth.