Hispano-Moresque ware was distinguished from the pottery of Christendom by the Islamic character of its decoration.[133] Polar-axis sundial: Early sundials were nodus-based with straight hour-lines, indicating unequal hours (also called temporary hours) that varied with the seasons, since every day was divided into twelve equal segments; thus, hours were shorter in winter and longer in summer. The idea of using hours of equal time length throughout the year was the innovation of Abu'l-Hasan Ibn al-Shatir in 1371, based on earlier developments in trigonometry by Muhammad ibn Jābir al-Harrānī al-Battānī (Albategni). Ibn al-Shatir was aware that "using a gnomon that is parallel to the Earth's axis will produce sundials whose hour lines indicate equal hours on any day of the year."