Timeline of time measurement technology
270 BCE - Ctesibius builds a popular water clock, called a clepsydra
46 BCE - Julius Caesar and Sosigenes develop a solar calendar with leap years
11th century - Sets of hourglasses were maintained by ship's pages to mark the progress of a ship during its voyage
11th century - Large town clocks were used in Europe to display local time, maintained by hand
1335 - First known mechanical clock, in Milan
1502 - Peter Henlein builds the first pocketwatch
1582 - Pope Gregory XIII, Aloysius Lilius, and Christopher Clavius introduce a Gregorian calendar with an improved leap year system
1655 - Cassini builds the heliometer of San Petronio in Bologna, to standardise Solar noon.
1656 - Christiaan Huygens builds the first accurate pendulum clock
1676 - Motion works and minute hand introduced by Daniel Quare
1680 - Second hand introduced
1737 - John Harrison presents the first stable marine chronometer, thereby allowing for precise longitude determination while at sea
1850 - Aaron Lufkin Dennison starts in Roxbury, Mass.U.S.A. the Waltham Watch Company and develops the American System of Watch Manufacturing.
1884 - International Meridian Conference adopts Greenwich Mean Time for consistency with Nevil Maskelyne's 18th century observations for the Method of Lunar Distances
1893 - Introduction by Webb C. Ball of the General Railroad Timepiece Standards in North America: Railroad chronometers
1928 - Joseph Horton and Warren Morrison build the first quartz crystal oscillator clock
1946 - Felix Bloch and Edward Purcell develop nuclear magnetic resonance
1949 - Harold Lyons develops an atomic clock based on the quantum mechanical vibrations of the ammonia molecule
1982 - The Federation of the Swiss Watch Industry FH is founded by the merger of two previous organisations
1983 - Radio-controlled clocks become common place in Europe
1994 - Radio-controlled clocks become common place in USA
