Clock face

A clock face is the part of an analog clock (or watch) that shows time using a flat surface with numbers and moving pointers called hands. The most common clock face has numbers from 1 to 12 around the edge, showing the hours. A shorter hour hand moves slowly around the face, making two full circles in one day. A longer minute hand moves faster, completing one circle every hour. Some clock faces also have a small second hand that moves even quicker, finishing a circle each minute.

Another type of clock face uses a 24-hour analog dial, often found in places like the military. Instead of numbers 1 to 12, it shows hours from 1 to 24 (or 0 to 23), and the hour hand makes just one circle in a full day. Some special clocks, like timers for sports, are made to count time in smaller pieces, such as minutes instead of hours.

Clock faces can show hours using different kinds of numbers, like Roman numerals or Hindu–Arabic numerals. Sometimes, clocks use both kinds together, with Roman numbers for hours and Arabic numbers for minutes. In watches and some clocks, the numbers might be removed completely, and instead, small marks or lines are used to show the time by the position of the hands.

Reading a modern clock face

Most modern clocks have numbers from 1 to 12 around the edge, with 12 at the top. These numbers show us the hour. Some clocks also have small lines or dots around the outside to help show minutes and seconds. To read the time, we look at the hands — the pointers — coming out from the center:

• A short, thick hand that shows the hour.
• A long, thin hand that shows the minutes.
• On some clocks, a very thin hand that shows the seconds.

All the hands move in a circle in a clockwise direction, following the numbers.

The seconds hand moves quickly, completing a full circle every minute. For each circle it makes, the minute hand moves to the next number. The minute hand moves slower, taking an hour to go around once. For each circle it makes, the hour hand moves to the next number. The hour hand moves the slowest, taking twelve hours to go around once, starting at 12 when the day begins and coming back to 12 when the day ends.

Historical development

The word clock comes from a medieval Latin word for "bell," clocca. Clocks first appeared in 13th-century Europe. These early clocks rang bells at certain times to call people to prayer. They were placed in tall towers so everyone could hear them.

Over time, clockmakers added a dial to show the time between bell rings. At first, a fixed hand pointed to numbers on a rotating dial. Later, the design changed so the hand moved around a fixed dial, which we still use today. Minute hands appeared around 1690 when clocks became more precise. Some precise clocks even added a third hand to show seconds. The hands move clockwise because this matches how shadows move on sundials.

French decimal time

Main article: Decimal time

During the French Revolution in 1793, France tried a new way of measuring time called decimal time. This system had 10 hours in a day, 100 minutes in an hour, and 100 seconds in a minute. Although some clocks were made with this system, people did not like it. France stopped using decimal time on 7 April 1795.

Stylistic development

Long ago, people marked the hours on clocks by carving them into metal and filling the spaces with black wax. Later, they used white enamel with black numbers, making it easier to read the time. At first, the numbers were painted on small pieces and placed on a metal base because they couldn’t make big pieces of enamel yet. Over time, they began making whole clock faces out of a single piece of enamel around the year 1735.

Today, many ads show clocks and watches set to about 10:10 or 1:50. This position looks like a smiling face or a person with their arms up, and it also keeps the company’s logo clear and easy to see. In the 1970s, a designer in Germany created a special watch called the Chromachron. Instead of numbers, it had a rotating disc with colors to show the time.

Technological obsolescence

In the 2010s, some schools in the United Kingdom started using digital clocks instead of analogue clocks in exam rooms. This change happened because many students found it difficult to read analogue clocks. Most smartphone and computer clocks are digital now, so some people think analogue clocks are not needed anymore. However, learning to read analogue clocks is still part of school lessons in the United States. Supporters believe this helps students practice basic math skills.