| Keeping track of time | | | | short pendulums. |
| Humans have been keeping track of time throughout | | | | Grandfather clocks get taller |
| the ages using everything from hourglasses to sundials. | | | | The first grandfather clocks did not keep time well. An |
| During the second half of the 13th century, the very | | | | early grandfather clock could lose as much as ten |
| first mechanical clocks were developed. These early | | | | minutes a day. In 1670 William Clement noticed that by |
| clocks were huge contraptions made with heavy iron | | | | making the pendulum in a clock longer he could make |
| frames and large gears, usually placed in church | | | | the clock keep better time. The advancements |
| towers and striking the church bell on the top of each | | | | resulted in an increase in precision that meant the |
| hour. Later enhancements led to an hour hand and the | | | | clocks held time to within a few seconds variance per |
| ability of the clocks to strike every quarter-hour. | | | | week. This was the start of the popularity of long |
| Eventually, during the first half of the 15th century, | | | | case clocks, later renamed grandfather clocks, due to |
| personal clocks started to appear. | | | | their ability to keep time so accurately. |
| The grandfather clock gets a boost from astronomers | | | | Final improvements to grandfather clocks |
| In 1582 Galileo Galilei discovered that you could use a | | | | In 1721 George Graham noticed that temperature |
| pendulum to keep time. He studied pendulum clocks, | | | | changes in the pendulum of a grandfather clock could |
| and drew what became the first designs for a | | | | cause it run slower or faster. Graham improved the |
| grandfather clock. In 1656 Christiaan Huygens applied | | | | grandfather clock design by compensating for the |
| what Galileo had discovered and developed the first | | | | temperature changes in the pendulums. His changes |
| pendulum clock, the prototype for the grandfather | | | | led to grandfather clocks that were accurate to 1 |
| clock. These clocks hung on walls and were | | | | second a day. Current grandfather clocks have been |
| affectionately entitled "wags-on-the-wall" due to their | | | | created by this and similar designs. |