Has anyone ever wondered how people in ancient times would keep a track of time, When there was no clock back in those days?
In medieval, age people used to keep track of time by using a candle. A candle is an ignitable thread embedded in wax.

This clock creation was first invented by King Alfred the Great of England in 878. He created a device that includes six candles where all were made up of wax. Each wax candle was 12 inches tall equivalent to its thickness. There were needles embedded in wax which shows the time. When a candle has burnt between the needles means an hour has passed. Keeping in mind these candles should burn steadily, if it is placed in draught then the candle will burn rapidly. So the candle needs to be placed in a holder which lets you see the marks on the candle, through this the candle remains protected from draught.
So keeping a track of time required a lot of candles, as each candle burned completely in four hours making each marking 20 minutes.
These clocks were also used as setting an alarm like a modern clock, but the only disadvantage was it did not make any noise. So people used to push nails in the candle at the desired time length, and when the candle is melted to that point the nail would fall and clank on the metal holder producing an alerting sound. There were many types of candle clocks that were made back in those days. One with the thread candle where the needles are tied with a thread and each hour is passed the needle would fall hanging along with the thread and another with needle candle was used to set an alarm.