Chelmsford Public Library

All about sundials, presented by J. Leon Poirier

eng

videorecording

All about sundials

Recorded at the Chelmsford Public Library on March 14, 2014

presented by J. Leon Poirier

Library hourFriday morning lecture series

Did you know that the Egyptians used sundials and French railroads set their clocks with sundials until 1920? Over the centuries, hundreds of different sundials have been made from giant dials 100 ft high to tiny ones hidden in signet rings. The most common sundials use the azimuth of the Sun to tell time while others use its altitude. We will show examples of the two types of sundials and explain how each works. You will learn how to convert sundial time to clock time and how to make your own sundial. We will also see that sundials not only keep accurate time but can also show many other important solar events including, for example, the times of sunrise and sunset, the dates of the equinoxes and solstices, the signs of the Zodiac, and even your birthday or anniversary. You will be able to examine many homemade sundials including diptych, shepherds, flag, analemma, horizontal and vertical, equatorial, cube, perforated and universal ring, and armillary sphere dials. You can even take home a handout that you can cut out to make your own equatorial sundial or armillary sphere sundial. Doctor Poirier has taught electrical engineering and physics at UMASS Lowell and Tufts University. He has published over 50 papers and reports and holds 15 patents in radar and related topics. He is a life member of the Minute Man Sail and Power Squadron where teaches piloting and celestial navigation. Among his interests are celestial navigation, 15th-18th century navigation instruments, and sundials. He and his wife enjoy traveling and have visited 45 countries

not applicable