The hollow cylindrical brass base has a compass inset into the top and a horizontal dial engraved. At the South end of the compass, a rod gnomon projects at an angle. The hour angles are very inaccurately drawn (they clearly do not have a common intersection). At the other side of the plate from the gnomon, an iron pillar supports the inclined octagonal brass volvelle. This carries two rotatable discs with hour scales and poor representations of the zodiac symbols.