Garden sundials are used as a clock that works via sun time, not clock time. Mathmeticians and historians love the concept of sundials and sun time. Positioning a Garden Sundial to read the time of day as accurately as possible requires some research and study. To make it easier for our customers, we've done all the research.
There are two different types of garden sundials. Horizontal Garden Sundials which lay flat on the ground or can be placed on a pedestal and Armillary sundials that are a bit more detailed in design and have a larger Gnomon.
Sundials need to point in the direction of True North, and the style (either a sharp straight edge or thin rod, often located at the edge or tip of the gnomon) must be aligned with the Earth's rotational axis. The direction of True North is not the same as the north magnetic pole, but instead is marked by the north celestial pole.
The sun will appear at times to be faster and slower than our watches read, again because sun time and clock time are not the same. The sun appears "fast" from mid-April through mid-June, and early September through late December. When the sun appears "fast" it will reach sun-noon (be directly overhead) not at 12:00:00 by your watch, but a few minutes earlier. When you are setting up your horizontal sundial, you want to know the time the sun is directly overhead. There are certainly more advanced methods of determining True North, and setting sundials for accuracy, but our horizontal garden sundials can be set using the methods above. You will enjoy watching how the shadows on your sundial change through the seasons and how sun time really works.
Garden and Armillary Sundials are often bought as gifts, and when traveling. Bringing home a sundial that was produced outside of your area of longitude will require that you check the angle of the gnomon. The gnomon is a bar or stretched wire parallel to the celestial axis, and the face is a semi-circle. A sundial made for the south of Spain will have an angle of 37 and will not tell the correct time if it is set up with the horizontal dial plate in Birmingham, Alabama where latitude is 52.5N. You should check the angle of your gnomon regardless of where it was purchased and is set up, just to be certain your sundial is ready to tell sun-time.
The research above should be able to set up a garden sundial as accurately as possible. Enjoying the beauty and function of your sundial will be a different kind of experience after learning about sun time vs. clock time, the direction of true north, and how to angle your gnomon correctly.