The above Equatorial dial is a hemisphere which has direct East, West, and North dials on the sides.
All the pictured dials were designed and constructed by my father and myself.
Usually any other lines, graphs, analemmas, mottos, and compass roses are called dial furniture.
The most common furniture is the zodiac lines, these lines (with the aid of the gnomon's nodus) show the date the Sun enters a new zodiac. These lines can be calculated for any date and therefore create an anniversary dial.
The dial above is an example of a SunTile anniversary dial. The zodiac lines on this particular dial show birthday's and other significant dates for the family. This dial also has a compass rose.
The graph of the Equation of Time. which converts Sundial time (local apparent time) to local mean time.
A compass rose (usually on a horizontal dial) shows the azimuth of the sun.
Mottos, sayings or poems included on the dial (a popular example is Tempus Fugit QuoQue Serpit).
Analemmas show the relation between the equation of time and the Suns declination.
A Sundial design contest was announced for Reutte, Austria. The closing date for an entry was 9/25/1998. The judging date was 10/3/1998.
Click here to see our entry.
Most sundials that are available (science shops, garden shops etc.) are not going to work without a little adjusting.
Many of these "popular" horizontal dials have a gnomon which is 45 degrees. As we know this means that this dial was, hopefully, designed for a latitude of 45 degrees (like Minneapolis, MN). Make sure by measuring the angle of the gnomon.
The gnomon needs to point to the North Celestial Pole (true North) so unless the angle of the gnomon is equal to the latitude the horizontal dial must be "tipped".
If the gnomon was measured to be 45 degrees, but the latitude is 30. Then there is a difference of -15 degrees between the gnomon and the latitude. So we must tip the whole dial so the the gnomon is lowered 15 degrees. If the latitude was greater than the angle of the gnomon then we would tip the whole dial so the gnomon is raised the correct amount.
These adjustments will correctly adjust for one latitude any properly constructed horizontal dial for a different latitude.
Why don't the sundials agree with the clocks? This is partly because of the Equation of Time.
Member of the North American Sundial Society