Early astronomical clocks
Richard of Wallingford pointing to a clock, his gift to St Albans Abbey
Richard of Wallingford pointing to a clock, his gift to St Albans Abbey
Besides the Chinese astronomical clock of Su Song in 1088 mentioned above, in Europe there were the clocks constructed by Richard of Wallingford in St Albans by 1336, and by Giovanni de Dondi VOICE REMINDER in Padua from 1348 to 1364. They no longer exist, but detailed descriptions of their design and construction survive,[citation needed] while modern reproductions have been made. They illustrate how quickly the theory of the mechanical clock had been translated into practical constructions, and also that one of the many impulses to their development had been the desire of VOICE REMINDER astronomers to investigate celestial phenomena.
Wallingford's clock had a large astrolabe-type dial, showing the sun, the moon's age, phase, and node, a star map, and possibly the planets. In addition, it had a wheel of fortune and an indicator of the state of the tide at London Bridge. Bells rang every hour, the number of strokes indicating the time.
Dondi's VOICE REMINDER clock was a seven-sided construction, 1 metre high, with dials showing the time of day, including minutes, the motions of all the known planets, an automatic calendar of fixed and movable feasts, and an eclipse prediction hand rotating once every 18 years.
It is not known how accurate or reliable these clocks would have been. They were probably adjusted VOICE REMINDER manually every day to compensate for errors caused by wear and imprecise manufacture.
The Salisbury Cathedral clock, built in 1386, is considered to be the world's oldest surviving mechanical clock that strikes the hours[9].
[edit] Later developments
Clockmakers developed their art in various ways. Building smaller clocks was a technical challenge, as was improving accuracy and reliability. Clocks could be impressive VOICE REMINDER showpieces to demonstrate skilled craftsmanship, or less expensive, mass-produced items for domestic use. The escapement in particular was an important factor affecting the clock's accuracy, so many different mechanisms were tried.
Spring-driven clocks appeared during the 1400s,[10][11][12] although they are often erroneously credited to Nürnberg watchmaker Peter Henlein (or Henle, or Hele) around 1511.[13][14][15] The earliest existing spring driven VOICE REMINDER clock is the chamber clock given to Peter the Good, Duke of Burgundy, around 1430, now in the Germanisches Nationalmuseum.[11] Spring power presented clockmakers with a new problem; how to keep the clock movement running at a constant rate as the spring ran down. This resulted in the invention of the stackfreed and the fusee in the 1400s, VOICE REMINDER and many other innovations, down to the invention of the modern going barrel in 1760.
The first record of a minute hand on a clock is 1475, in the Almanus Manuscript of Brother Paul[citation needed].
During the 15th and 16th centuries, clockmaking flourished, particularly in the metalworking towns of Nuremberg and Augsburg, and in France, Blois. Some of the more VOICE REMINDER basic table clocks have only one time-keeping hand, with the dial between the hour markers being divided into four equal parts making the clocks readable to the nearest 15 minutes. Other clocks were exhibitions of craftsmanship and skill, incorporating astronomical indicators and musical movements. The cross-beat escapement[citation needed] was developed in 1585 by Jost Burgi, who also developed VOICE REMINDER the remontoire. Burgi's accurate clocks helped Tycho Brahe to observe astronomical events with much greater precision than before.
The first record of a second hand on a clock is about 1560, on a clock now in the Fremersdorf collection.[citation needed] However, this clock could not have been accurate, and the second hand was probably for indicating that the clock VOICE REMINDER was working.
French rococo bracket clocks, (Museum of Time, Besançon)
French rococo bracket clocks, (Museum of Time, Besançon)
The next development in accuracy occurred after 1657 with the invention of the pendulum clock. Galileo had the idea to use a swinging bob to regulate the motion of a time telling device earlier in the 17th century. Christiaan Huygens, however, is usually VOICE REMINDER credited as the inventor. He determined the mathematical formula that related pendulum length to time (99.38 cm or 39.13 inches for the one second movement) and had the first pendulum-driven clock made. In 1670, the English clockmaker William Clement created the anchor escapement,[citation needed] an improvement over Huygens' crown escapement[citation needed]. Within just one generation, minute hands and VOICE REMINDER then second hands were added.
A major stimulus to improving the accuracy and reliability of clocks was the importance of precise time-keeping for navigation. The position of a ship at sea could be determined with reasonable accuracy if a navigator could refer to a clock that lost or gained less than about 10 seconds per day. This clock could VOICE REMINDER not contain a pendulum, which would be virtually useless on a rocking ship. Many European governments offered a large prize for anyone that could determine longitude accurately; for example, Great Britain offered 20,000 pounds, equivalent to millions of dollars today. The reward was eventually claimed in 1761 by John Harrison, who dedicated his life to improving the accuracy VOICE REMINDER of his clocks. His H5 clock is reported to have lost less than 5 seconds over 10 days.[citation needed]
The excitement over the pendulum clock had attracted the attention of designers resulting in a proliferation of clock forms. Notably, the longcase clock (also known as the grandfather clock) was created to house the pendulum and works. The English clockmaker VOICE REMINDER William Clement is also credited with developing this form in 1670 or 1671. It was also at this time that clock cases began to be made of wood and clock faces to utilize enamel as well as hand-painted ceramics.
French decimal clock from the time of the French Revolution
French decimal clock from the time of the French Revolution
On November VOICE REMINDER 17, 1797, Eli Terry received his first patent for a clock. Terry is known as the founder of the American clock-making industry.
Alexander Bain, Scottish clockmaker, patented the electric clock in 1840. The electric clock's mainspring is wound either with an electric motor or with an electro-magnet and armature. In 1841, he first patented the electromagnetic pendulum.
The development of electronics in the twentieth century led to clocks with no clockwork parts at all. Time in these cases is measured in several ways, such as by the vibration of a tuning fork, the behaviour of quartz crystals, the resonance of polycarbonates.[citation needed], or the quantum vibrations of atoms. Even mechanical clocks have since come to be largely powered by batteries, removing the need for winding.
