page_title: Clock face
section_title: Historical development
hierarchical_section_title: Clock face / Historical development
caption_attribution_description: Polski: Fragment zegara astronomicznego, w: pl:Kościół Mariacki w Gdańsku English: Part of the astronomical clock in the w: en:St. Mary's Church, Gdańsk
context_page_description: A clock face is the part of an analog clock that displays time through the use of a flat surface with referencing markings — called a dial, and revolving pointer rods — called hands. In its most basic, globally recognized form, the periphery of the dial is numbered 1 through 12 indicating the hours in a 12-hour cycle, and a short hour hand makes two revolutions in a day. A long minute hand makes one revolution every hour. The face may also include a second hand, which makes one revolution per minute. The term is less commonly used for the time display on digital clocks and watches.
  A second type of clock face is the 24-hour analog dial, widely used in military and other organizations that use 24-hour time. This is similar to the 12-hour dial above, except it has hours numbered 1–24 around the outside, and the hour hand makes only one revolution per day. Some special-purpose clocks, such as timers and sporting event clocks, are designed for measuring periods less than one hour. Clocks can indicate the hour with Roman numerals or Hindu–Arabic numerals, or with non-numeric indicator marks.
context_section_description: The word clock derives from the medieval Latin word for "bell"; clogga, and has cognates in many European languages.  Clocks spread to England from the Low Countries, so the English word came from the Middle Low German and Middle Dutch Klocke.   The first mechanical clocks, built in 13th-century Europe, were striking clocks: their purpose was to ring bells upon the canonical hours, to call the local community to prayer.  These were tower clocks installed in bell towers in public places, to ensure that the bells were audible over a wide area.  Soon after these first mechanical clocks were in place people realized that their wheels could be used to drive an indicator on a dial on the outside of the tower, where it could be widely seen.
  Before the late 14th century, a fixed hand (often a carving literally shaped like a hand) indicated the hour by pointing to numbers on a rotating dial; after this time, the current convention of a rotating hand on a fixed dial was adopted. Minute hands (so named because they indicated the small, or minute, divisions of the hour) only came into regular use around 1690, after the invention of the pendulum and anchor escapement increased the precision of time-telling enough to justify it. In some precision clocks, a third hand, which rotated once a minute, was added in a separate subdial. This was called the "second-minute" hand (because it measured the secondary minute divisions of the hour), which was shortened to "second" hand. The convention of the hands moving clockwise evolved in imitation of the sundial. In the Northern hemisphere, where the clock face originated, the shadow of the gnomon on a horizontal sundial moves clockwise during the day.
caption: 15th-century rotating dial clock face, St. Mary's Church, Gdańsk, Poland.
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