Candle clock
Encyclopedia
A candle clock is a thin candle
with consistently spaced markings (usually with numbers), that when burned, indicate 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. A candle clock could be easily transformed into a timer by sticking a heavy nail into the candle at the mark indicating the desired interval. When the wax surrounding the nail melts, the nail clatters onto a plate below.
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 (520 AD). Here, the graduated candle supplied a means of determining time at night. Similar candles were used in Japan
until the early 10th century.
His device consisted of six candles made from 72 pennyweights 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 and earlier, famously by King Alfred the Great of England, first by counting the number of candles of a specific size burnt, and later by use of a graduated candle.
The most sophisticated candle clocks known to date, however, were those 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
described one of al-Jazari's candle clocks as follows:
Candle
A candle is a solid block or cylinder of wax with an embedded wick, which is lit to provide light, and sometimes heat.Today, most candles are made from paraffin. Candles can also be made from beeswax, soy, other plant waxes, and tallow...
with consistently spaced markings (usually with numbers), that when burned, indicate 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. A candle clock could be easily transformed into a timer by sticking a heavy nail into the candle at the mark indicating the desired interval. When the wax surrounding the nail melts, the nail clatters onto a plate below.
Chinese poetry
Chinese poetry is poetry written, spoken, or chanted in the Chinese language, which includes various versions of Chinese language, including Classical Chinese, Standard Chinese, Mandarin Chinese, Cantonese, Yue Chinese, as well as many other historical and vernacular varieties of the Chinese language...
by You Jiangu (520 AD). Here, the graduated candle supplied a means of determining time at night. Similar candles were used in Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
until the early 10th century.
His device consisted of six candles made from 72 pennyweights 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 and earlier, famously by King Alfred the Great of England, first by counting the number of candles of a specific size burnt, and later by use of a graduated candle.
Al-Jazari
Abū al-'Iz Ibn Ismā'īl ibn al-Razāz al-Jazarī was a Muslim polymath: a scholar, inventor, mechanical engineer, craftsman, artist, mathematician and astronomer from Al-Jazira, Mesopotamia, who lived during the Islamic Golden Age...
in 1206. It included a dial
Dial (measurement)
A dial is generally a flat surface, circular or rectangular, with numbers or similar markings on it, used for displaying the setting or output of a timepiece, radio, clock, watch, or measuring instrument...
to display the time and, for the first time, employed a bayonet fitting
Bayonet mount
A bayonet mount or bayonet connector is a fastening mechanism consisting of a male side with one or more pins, and a female receptor with matching L slots and spring to keep the two parts locked together....
, a fastening mechanism
Fastener
A fastener is a hardware device that mechanically joins or affixes two or more objects together.Fasteners can also be used to close a container such as a bag, a box, or an envelope; or they may involve keeping together the sides of an opening of flexible material, attaching a lid to a container,...
still used in modern times. Donald Routledge Hill
Donald Routledge Hill
Donald Routledge Hill was an English engineer and historian of science and technology.Alongside more general works on the history of technology, he wrote works on the history of medieval Arabic science and technology, and translated The Book of Knowledge of Ingenious Mechanical Devices of the...
described one of al-Jazari's candle clocks as follows:
The candle, whose rate of burning was known, bore against the underside of the cap, and its wick passed through the hole. Wax collected in the indentation and could be removed periodically so that it did not interfere with steady burning. The bottom of the candle rested in a shallow dish that had a ring on its side connected through pulleys to a counterweight. As the candle burned away, the weight pushed it upward at a constant speed. The automata were operated from the dish at the bottom of the candle.