TIME KEEPING

It is not known specifically where and when candle clocks were first used; however, their earliest mention comes from a Chinese poem, written in 520 by You Jianfu. According to the poem, the graduated candle was a means of determining time at night. Similar candles were used in Japan until the early 10th century.

Although candles could not be used to find a specific time they were instrumental in able to indicate passage of predetermined periods of time. For example the Anglo-Saxon king Alfred the Great (c. 849 - 899) used graduated candles also known as candle-clocks. He used this candle to divide up his day into equal periods of study and prayer, royal duties, and rest. There were lines around the side to show the passing of each hour.

Later, 24-hour candles were invented based on the same concept. During the Sung dynasty in China (960–1279) calibrated candles and sticks of incense measured time. The concept of this clock utilized six different threads with weights on the end. These were draped over an incense stick at regular intervals and as the incense burned, the threads simultaneously burned one by one and the weights dropped onto a sounding plate below. Sometimes the sticks of incense had varying so that hours were marked by a change in fragrance.

Oil-lamp clocks, these early timekeeping devices consisted of a graduated glass reservoir to hold oil — usually whale oil, which burned cleanly and evenly — supplying the fuel for a built-in lamp. As the level in the reservoir dropped, it provided a rough measure of the passage of time.

The candle clock was also used as a timer. A heavy nail inserted onto the candle at the indicted mark would fall down onto a hard surface after the wax surrounding the nail melted

In the days leading to Christmas some people burn a candle a set amount to represent each day, as marked on the candle. The type of candle used in this way is called the Advent candle, although this term is also used to refer to a candle that decorates an Advent wreath.