An armillary sundial also called an armillary sphere is a representation of both the terrestrial globe and celestial sphere. Often highly decorated, these are beautiful sundials.
This Sundials for Starters appeared in The Compendium in March 2014
Robert L. Kellogg, Ph.D.
In 1902 Alice More Earle in her book Sun-Dials and Roses of Yesterday commented:
“Of course, there are in the United States many houses that manufacture optical and mathematical instruments and also make sun-dials. There are also those who make and sell very pretty brass dials, made to look well … regardless of the shape of the gnomon or drawing of the hour lines. I know no individual, however, save Captain Bailey, who makes accurate sun-dials for all latitudes.” [Fig. 1 of Captain John S. Bailey, 19th century dial maker - Earle].
Mechanical Dialing and a Laser Trigon
The most popular ways to lay out sundials involves computation, geometry, or a combination of both. These methods assume the dial will be created on a regular surface, such as flat horizontal or vertical dials or circularly curved equatorial dials.
A less known method is mechanically drawing dial lines using a string or laser beam to project artificial “sunbeams” to show where light and shadow fall. This technique can be used on both regular and irregular surfaces. We start by describing the principles of a trigon.
Eagle Scout Project by
Parker Middle School, Howell, MI
The "Human Sundial", technically called an analemmatic sundial, allows one's own shadow to cast the time of day. The sundial works with students of any height, where all they have to do is stand on the current day of year mark of a central walkway. The analemmatic sundial can be painted onto concrete or asphalt playgrounds or, using markers and a brick or paver-stone walkway, be designed for a flat, grassy area.
By Robert L. Kellogg, Ph. D.
Benjamin Banneker, 1731-1806 , is one of the nation's best-known African American inventors. He was born in Maryland and in 1791 played an important part in surveying the newly designed Federal Territory, now called the District of Columbia. In his youth, Banneker was inspired to build his own clock after an acquaintance gave him a watch. He took the watch apart to find out how it worked and made drawings of each component, and based on his drawings, he carved larger versions of the components out of wood and constructed a clock that kept accurate time for more than 50 years. As mathematician, he designed an Almanac that was a rival of Benjamin Franklin’s famous publication.
As astronomer, clockmaker, and mathematician, he was expected to know how to design sundials, although none exist bearing his mark. In an age before pocket calculators, how would Banneker design a sundial? The graphical method is available in modern texts such as Waugh’s 1973 classic “Sundials: Theory and Construction”. Want to lay out a horizontal sundial without sines, cosines, and tangents? Then this “Sundials for Starters” is for you.