Procedure for use:

i) Raise the latitude quadrant (the curved brass part marked 0-60) to the vertical position.

ii) Raise the gnomon (the triangular-shaped brass piece) to the vertical position.

iii) Tilt the hinged chapter ring (the circle with the Roman numerals) to your latitude.

iv) Place the instrument on the horizontal surface and orientate it so that when the compass needle comes to rest the “N” point (red) is over the North of the lower compass rose.

v) The shadow of the gnomon on the chapter ring will give you the time.