The North American Sundial Society (NASS) is "interested in the study, development, history, and preservation of sundials and the art of dialing throughout the continent." Users can find applets that display the daily and annual paths of the sun and moon. The NASS message board allows sundial hobbyists the chance to correspond with each other. The website provides an extensive list of the sundials...

Everyday Mysteries: Fun Facts from the Library of Congress offers an explanation for how an hourglass measures time. Learn about the careful calibration of this age-old timepiece and what factors affect the accuracy of the sand clock. The website provides links to related websites that provide a brief history of the hourglass and sell custom hourglasses. The U.S Official Time website, which is...