Level consisting of a frame to which are attached two parallel telescopes pointing in opposite directions. A plumb line housed in a miniature kiosk with windows passes in front of the eyepieces of two micrometer microscopes at right angles. These are used to verify the perfectly horizontal position of the telescopes relative to the vertical plane of the plumb line. The arrangement enabled the telescopes to align two points on the horizontal plane. The instrument, probably designed by Felice Fontana, was built in the Museo di Fisica e Storia Naturale workshop.