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From Sundials to Watches and Beyond:
The History of Telling Time

Telling time has always been important. For example, farmers need to know when to plant their crops to expect the best results. Today there is a clock on your phone, in your car, on your computer screen and in all likelihood, on the wall of the room you’re in right now. However, it hasn’t always been that way. It is said that people first realized they could tell time by the shadows that objects cast when touched by sunlight. Before any such object was invented for this task specifically, people likely used trees, poles and even large manmade structures such as pyramids.

  • The Story of Time Measurement: The clock and watch collection of St. Edmundsbury’s Faces of Time gallery.
  • The History of Time: Where did the concept of time and day come from?
  • Time History: Some facts about the development of clocks and other timepieces.
  • The Lunar Clock: There is a way to determine about what time it is just by looking at the moon.
  • Brief History of Time Measurement: Learn about and look at some early timepieces that preceded the mechanical clock.
  • The Earliest Clock: Read about how ancient people used the sun to determine what time it was.
  • Telling Time without a Clock: Before clocks were invented, how did people know it was time to wake up, work, shop or go to bed?
  • History of Watches: Take a look at a timeline that covers watches from 3500 BC (long before they existed as we know them today) all the way to 2008.
  • Aztec Calendar Wheels: See how the Aztec tribes determined the time and observe the similarities and differences between their wheels and our modern calendar.

Sundials & Water Clocks

In ancient Egypt, people used shadow clocks to keep track of the hours. Using the shadows that the sun creates, the Egyptians were the first to divide the day into twenty-four hours. Meanwhile, other cultures were developing time-telling devices of their own. All of these devices were versions of sundials – circular timepieces with evenly-spaced lines and a gnomon that casts a shadow when the sun shines on it. Sundials were the first reliable timepieces. However, since sundials work by casting a shadow in a particular direction, they do not work at night. To fix this issue, Prince Amenemhet invented a water clock. This early version of an hour glass was simply a water bucket with a small hole. Amenemhet measured how much water would leak out in an hour’s time and then mark the bucket accordingly. Water clocks were not without error, however. The main issue with water clocks is that there are variable factors. For example, temperature can affect the speed of water flow.

Mechanical Clocks

The first mechanical clock was invented during the 1200s. It is unknown who the original pioneer was, but we can determine the approximate date based on their appearance in historical records. Most of the clocks invented throughout the Thirteenth and Fourteenth Centuries were inaccurate, though there were rare gems among the rest. A clock built in 1386 is still running in Salisbury, England today! There were a number of inventors who are responsible for improving the reliability of mechanical clocks. One is Christiaan Huygens who, in the 1650s, designed the pendulum clock. Based on Galileo’s hypotheses earlier that century, the pendulum clock used a swinging bob to regulate the motion of the hands. Huygens was also a knowledgeable astronomer who discovered Saturn’s rings.

John Harrison

After a tragedy in 1707 that destroyed four British fleet ships and killed two thousand soldiers, the British government challenged anyone to invent a clock that was accurate to the second and could be used at sea to determine longitude. John Harrison rose to the occasion, inventing the marine chronometer. His fourth design for the device was tested at sea in 1761 and proved to be only five seconds off. Nearly thirty-five years after he had invented the first model, Harrison was awarded the prize money for the challenge.

Eli Terry

A third inventor who impacted the history and development of timepieces dramatically was Eli Terry. This Connecticut-born clockmaker was significant because he developed a way to mass produce clocks, thus reducing the work required and the sale price. Prior to Terry, clocks were a luxury item found in the homes of the well-to-do. After Terry’s 4000 clock project in 1810, they could be found all across America.  

  • Terry Timeline: What were the major events in Eli Terry’s life?
  • Inventor Profile: Who was Eli Terry and how has his greatest invention impacted the world?
  • Eli Terry: A brief biography of Eli Terry.

Telling Time during the Twentieth Century

In the Twentieth Century, there was certainly no shortage of clocks. However, people began developing smaller, portable and even digital clocks. Portable clocks were no new concept; spring-loaded pocket watches had been around since the 1600s. However, there was a new fad underway: wristwatches. The concept of wristwatches dates back to the 1880s – but back then they were simply pocket watches attached to homemade bands. In the early Twentieth Century, some manufacturers began to develop “bracelet watches” or “wristlets,” but they were primarily thought of as feminine jewelry. The attitude toward wristwatches changed gradually with time, but the gender discrepancy is said to have been killed in 1970 with the invention of the electric wristwatch. Men attracted to high-tech gadgetry bought them up, and continued to do so as companies added more and more features. By the end of the 1980s, there were watches with built-in alarms, stop clocks, calculators and even TVs.  

Atomic Clocks

Atomic clocks are hyper-accurate clocks that use electronic transition frequency to keep time. They work by exposing certain atoms to certain signals, changing their levels of energy. The two most common elements used are cesium and rubidium. Though the technology has been experimented with since the 1800s, the first atomic clock was officially invented in 1949. Atomic clocks are not practical and are generally not found in the home; however they serve a greater importance: the time determined by atomic clocks is that which we use to go about our day-to-day activities. Though a few minutes is not often critical, the time displayed on your car stereo is considered inaccurate if it does not match the official time determined by atomic clocks.

  • Atomic Clocks: What are atomic clocks and how do they work?
  • Clockworks: Britannica presents a beautiful exhibit on telling time using sundials, clocks and even shows how to measure to the atomic second.
  • A Walk Through Time: The National Institute of Standards and Technology walks you through the evolution of time measurement from ancient calendars to today.