Combined nocturnal, sundial and tide table.
Rare example of instrument with tide table for coastal towns on Europe on the rotatable disc.
Main disc has date scale with named months, also a lunar-age scale anticlockwise divided 1 - 30 by 1.
Rotatable disc has notches rather than teeth for hours 4 to 8 pm. Within the hour scale is a radial table for calculating the high tide in various towns around the North Sea.
Pointer is marked for Ursa Major.
Reverse carries a sundial and a compass with 16 marked points, blued arrow needle, glass cover and brass lid.
Reverse has an unequal degree scale and hour scale for latitude 53 N
Shaped and highly decorated gnomon.