Sun clock

Place a flowerpot with a long stick fixed into the hole at the bottom in a spot, which is sunny, all day. The sticks shadow moves along the rim of the pot as the sun moves. Each hour by the clock mark the position of the shadow on the pot. If the sun is shining, you can read off the time. Because of the rotation of the earth the sun apparently passes over us in a semi circle. In the morning and evening its shadow strikes the pot superficially, while; it midday, around 12 oclock, the light incidence is greatest. The shadow can be seen particularly clearly on the sloping wall of the pot.