21st Century - Located on the 6th-tallest tower in the world, the Makkah royal clock face is 43m across, 35 times the size of 'Big Ben' clockface and can be see from 25km away.
20th Century - A 1999 article about the timepiece in Grand Central mentioned its opal faces. An anonymous wikipedia contibutor then claimed that each face was made of opal, & the clock was worth $10-20 million. Though this entry was quickly deleted for being unsubstantiated, a tourist guide added the 'fact' to his information, and an urban legend was born. The clock was designed by Henry Edward Bedford & cast in Waterbury, Connecticut. Its mechanism was designed by the Self Winding Co.
19th Century - Though Big Ben was originally the nickname of the biggest bell, the entire clock tower has become known by the name. It was designed by Augustus Pugin in a neo-Gothic style. When completed in 1859, its clock was the largest and most accurate four-faced striking and chiming clock in the world.
18th Century - Now known as 'H1', the timekeeper is unaffected by the motion of a ship owing to its two interconnected swinging balances. It compensates for changes in temperature &, thanks to extensive anti-friction devices, runs without any lubrication. It was the first relatively successful marine timekeeper of any kind and was the toast of London when Harrison unveiled it in 1735. It is one of the great milestones in clock-making history.
17th Century - Johannes Van Ceulen made this bracket clock in The Hague, Holland, in collaboration with Christiaan Huygens. Huygens (1629-1693) patented the design for the first practical pendulum clock in 1657. Smithsonian.
16th Century - The Münster astronomical clock was built between 1540 and 1542, is one of the most significant monumental clocks in the German-speaking world. It belongs to the so-called 'Family of Hanseatic Clocks', of which other examples survive in Gdańsk, Rostock, Stralsund & Stendal in near-original condition. Situated in a vault between the high choir & the south arm of the ambulatory it is one of the few existing monumental clocks that turns anti-clockwise.
15th Century - The Prague Astronomical Clock or Prague Orloj (Czech: Pražský orloj [praʃskiː orloj]) is a medieval astronomical clock attached to the Old Town Hall in Prague, the capital of the Czech Republic. It was first installed in 1410, making it the third-oldest astronomical clock in the world & the oldest clock still in operation. It was created by clockmaker Mikuláš of Kadaň & Charles University professor of mathematics & astronomy, Jan Šindel.
14th Century - The Wells Cathedral clock is an astronomical clock in the north transept of Wells Cathedral, England. The surviving mechanism, dated to between 1386 and 1392, was replaced in the 19th century, and was eventually moved to the Science Museum in London, where it continues to operate. The dial represents the geocentric view of the universe, with Sun and Moon revolving round a central fixed Earth. It may be unique in showing a philosophical model of the pre-Copernican universe.
13th Century - A 1240 statue of a youth with a sundial of the canonical hours; the divisions of the day in terms of fixed times of prayer - matins & lauds (usually counted as a single hour), in the middle of the night; prime, at sunrise; terce, 9 a.m.; sext, noon; none, 3 p.m.; vespers, sunset; & compline, bedtime. It is now in the Musee de l'Oeuvre Notre Dame, Strasbourg, France
12th Century - From Studenica Monastery, Serbia. The semi-circle hour plate (r=21cm) is divided into 12 equal hour sectors. In Byzantine fashion, the sectors are numerated by letters A, B, G, D, E, S , Z, H in the Cyrillic alphabet. The last quadrant of the sundial is missing (the one with Q, I, IA, IB). The gnomon is missing too, and it must have been fixed perpendicularly on the wall, in the center of the semi-circle shaped hour plate.
11th Century - In 1086 the Song Emperor commissioned Chinese polymath Su Song's greatest project - the 40-foot-tall, water-powered astronomical clock-tower constructed in Kaifeng. The wooden pilot model completed in 1088, the bronze components cast by 1090, while the wholly finished work was completed by 1094, during the reign of Emperor Zhezong. Destroyed in 1127, a scale model was made in the Science Museum, London, 1965.
9th Century - This sundial is located in the central courtyard of the Sidi Okba Mosque, Kairouan, Tunisia. It is situated on a raised platform & is unique for the role it plays: recording the 5 times a Muslim must pray: Half an hour before sunrise ('asr'), at sunrise ('fajr'), at noon when the sun is at its zenith ('dhuhr'), the afternoon ('maghrib'), & an hour and a half after sunset ('isha').