A candle clock is a thin candle with consistently spaced marking that, when burned, indicates the passage of periods of time. While no longer used today, candle clocks provided an effective way to tell time indoors, at night, or on a cloudy day.

History

It is unknown where and when candle clocks were first used. The earliest reference to their use to occurs in a Chinese poem by You Jiangu (AD 520). Here, the graduated candle supplied a means of determining time at night. Similar candles were used in

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

until the early 10th century. You Jiangu's device consisted of six candles made from 72 pennyweights (24 grains each), of wax, each being 12 inches high, of uniform thickness, and divided into 12 sections each of one inch. Each candle burned away completely in four hours, making each marking 20 minutes. The candles were placed for protection inside cases made of a wooden frame with transparent horn panels in the sides. Similar methods of measuring time were used in medieval churches. The invention of the candle clock was attributed by the

Anglo-Saxons The Anglo-Saxons, in some contexts simply called Saxons or the English, were a Cultural identity, cultural group who spoke Old English and inhabited much of what is now England and south-eastern Scotland in the Early Middle Ages. They traced t ...

Alfred the Great Alfred the Great ( ; – 26 October 899) was King of the West Saxons from 871 to 886, and King of the Anglo-Saxons from 886 until his death in 899. He was the youngest son of King Æthelwulf and his first wife Osburh, who both died when Alfr ...

, king of

Wessex The Kingdom of the West Saxons, also known as the Kingdom of Wessex, was an Anglo-Saxon Heptarchy, kingdom in the south of Great Britain, from around 519 until Alfred the Great declared himself as King of the Anglo-Saxons in 886. The Anglo-Sa ...

. The story of how the clock was created was narrated by

Asser Asser (; ; died 909) was a Welsh people, Welsh monk from St David's, Kingdom of Dyfed, Dyfed, who became Bishop of Sherborne (ancient), Bishop of Sherborne in the 890s. About 885 he was asked by Alfred the Great to leave St David's and join ...

, who lived at Alfred's court and became his close associate. Alfred used six candles, each made from 12

pennyweight A pennyweight (dwt) is a unit of mass equal to 24 grains, of a troy ounce, of a troy pound, avoirdupois ounce and exactly 1.55517384 grams. It is abbreviated dwt, ''d'' standing for ''denarius'' (an ancient Roman coin), and later ...

s of wax, and made to be high and of a uniform thickness. The candles were marked at intervals of an

inch The inch (symbol: in or prime (symbol), ) is a Units of measurement, unit of length in the imperial units, British Imperial and the United States customary units, United States customary System of measurement, systems of measurement. It is eq ...

. Once lit, they were protected from the wind by being placed in a lantern made of wood and transparent

horn Horn may refer to: Common uses * Horn (acoustic), a tapered sound guide ** Horn antenna ** Horn loudspeaker ** Vehicle horn ** Train horn *Horn (anatomy), a pointed, bony projection on the head of various animals * Horn (instrument), a family ...

. It would have taken 20 minutes to burn down to the next mark; the candles, burning one after the other, lasted for 24 hours.

Al-Jazari

Al-Jazari Badīʿ az-Zaman Abu l-ʿIzz ibn Ismāʿīl ibn ar-Razāz al-Jazarī (1136–1206, , ) was a Muslim polymath: a scholar, inventor, mechanical engineer, artisan and artist from the Artuqid Dynasty of Jazira in Mesopotamia. He is best known for ...

described a candle clock in 1206. It included a dial to display the time and, for the first time, employed a bayonet fitting, a fastening mechanism still used in modern times. The English engineer and historian

Donald Routledge Hill Donald Routledge Hill (6 August 1922 – 30 May 1994)D. A. King, “In Memoriam: Donald Routledge Hill (1922-1994)”, ''Arabic Sciences and Philosophy,'' Volume 5 / Issue 02 / September 1995, pp 297-302 was a British engineer and historian of s ...

described one of al-Jazari's candle clocks as follows:

References

Sources

* * Turner, Anthony J. The Time Museum, Volume I, Time Measuring Instruments; Part 3, Water-clocks, Sand-glasses, Fire-clocks {{DEFAULTSORT:Candle Clock Candles Chinese inventions Clocks Japanese inventions ru:Огненные часы#Свечные часы