Sundial. Sundial on top of a column in sunlight. Also seen in the background is a church clock tower. The sundial measures time using a shadow formed by the spike (gnomon). This shadow moves across the face of the sundial as the Sun moves across the sky. Each of the lines which radiate out from the gnomon denote an hour of the day. The time is read by seeing which line the gnomon's shadow lies on. This particular sundial is part of a war memorial outside the church of St Mary the Virgin, Wooton, England.