Sundial compasses are used to tell the time, using the shadow cast by an indicator, also known as a gnomon, onto a surface marked in hours. The origins of sundial compasses are the Nuremberg ivory sundials and the French Butterfield Dials. The gnomon has to be aligned with the earth’s polar axis and this requires both the Latitude and the direction to be known. This is why Sundial compasses are fitted with a compasses and why they are either marked for a specific latitude or have an adjustable gnomon.
In the 18th/19th C the basic design evolved with both fixed and adjustable gnomons mounted on chapter rings.
The design evolved into the 20th C with companies like Silva producing a very compact Sun Watch.
Suncompasses are also used for specific purposes such as photography where it is useful to know where the sun will be during the course of the day.
There is a lot of scope for being creative with the design and this is an example of a French Sundial compass, probably mid 20th C.
