Crossing cones of vision with balance and angle figures

This richly illustrated leaf sets several diagrams among blocks of mirror-script, and the bundle gives no transcription, so the text is described only by what is drawn. Its central figure is two cones meeting tip to tip at a single point, an hourglass of straight lines that gather from a circle at the bottom, cross at the point, and spread again above, the pattern by which an image is inverted through an aperture or the eye. At the upper left is a wheel or balance, a circle with a central hub and two weights hung symmetrically below it, while at the right a graduated quarter-circle sector and, lower down, a circle crossed by two diameters carry angle and construction studies. Later library stamps mark the page.