The East face of Ignazio Danti's astronomical quadrant erected in 1572 on the facade of Santa Maria Novella, Florence. Its main purpose was to observe and measure the altitude of the sun at the meridian on the Equinoxes, from which it was possible to calculate the Ecliptic Obliquity (the axial tilt of the earth). The quadrant contains 3 solar clocks which show the time in either Babilonic, Italic, or Astronomical hours. Danti's calculations of the angular distance between the Tropics and the axial tilt of the Earth in 1574 are inscribed on the bracket below. Under the inscriptions is an east-facing sundial inscribed with French hours, that is, counted from midnight.