The Lyman Briggs dial is an important American polar dial that indicates standard time. It is located on the campus of the National Institute of Standards and Technology at Gaithersburg Maryland where it commemorates Lyman James Briggs who was the Director of NIST, which was then The Bureau of Standards, from 1933 to 1945.

The dial has three faces on one planar surface. The upper and lower faces utilize half-analemmas as hour lines to indicate standard time corrected for the longitude. Each is used for half the year. The time shown in the photograph of the dial face is about 10:30 AM on a date when the sun's declination was a few degrees north of the equator.

The sunburst at the top of the dial surrounds the aperture through which the sun falls on an analemma, which is located behind the dial. The third face is in the center, and indicates local solar time.The dial was designed by R. Newton Mayall, the author of Sundials, How to Know, Use, and Make Them. I was pleased to be able to recreate Mayall's inspired design and produce a drawing of the dial face using DesignCAD 2D and its internal programming language. The drawing shows more detail than the photograph.

A photograph of the side of the dial shows the shape of the gnomons, and the position and shape of the analemma receiving surface behind the dial face.

Since the analemma is projected on a semi-cylindrical surface, it is somewhat more compressed north to south than we are used to seeing. Mayall has included the Time Zone offset on the analemma as well as the declination and the meridian altitude.