Gnomon

• A Device used in the Ancient World to measure the height and angle of Celestial Objects, mainly the Sun, but also Moon and Stars.

Use as a Sundial

• The Gnomon was the Triangular blade set at a right angle on a Block of wood.
• The Blade points to the Pole Star at that Latitude, and the Sun’s shadow can be read off from a series of marks on the Block, to give the time.

Use in calculating Latitude

• A vertical stick, embedded in a block of wood, with a tiny sphere at the top.
• The stick and sphere would cast a shadow on the block of wood.
• Knowing the date and time, it is possible to calculate the elevation of the Sun and derive the Latitude from a set of tables.