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 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 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 were a Cultural identity, cultural group who inhabited England in the Early Middle Ages. They traced their origins to settlers who came to Britain from mainland Europe in the 5th century. However, the ethnogenesis of the Anglo- ...
to
Alfred the Great, king of
Wessex
la, Regnum Occidentalium Saxonum
, conventional_long_name = Kingdom of the West Saxons
, common_name = Wessex
, image_map = Southern British Isles 9th century.svg
, map_caption = S ...
. The story of how the clock was created was narrated by
Asser
Asser (; ; died 909) was a Welsh monk from St David's, Dyfed, who became Bishop of Sherborne in the 890s. About 885 he was asked by Alfred the Great to leave St David's and join the circle of learned men whom Alfred was recruiting for his ...
, 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, approximately 0.054857 avoirdupois ounce and exactly 1.55517384 grams. It is abbreviated dwt, ''d'' standing for ''denarius'' (an ancien ...
s of wax, and made to be high and of a uniform thickness. The candles were marked at intervals of an
inch. Once lit, they were protected from the wind by being placed in a lantern made of wood and transparent
horn. 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
The most sophisticated candle clock known to date, however, was that of
Al-Jazari 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.]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 sc ...
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