The candle alarm clock is a specific form of the fire watch. Candle clocks were mentioned in Islamic sources of the 10th and 11th centuries, but were probably known far earlier. The candle has hour markers. The time is displayed by the even burning. This clock can also be used as an alarm clock or timer by dropping small weights attached to chains at scheduled times when the candle has burned out accordingly. They fall on a small bell that is part of the candlestick. The sound signals that a certain point in time has been reached.
The time is displayed by the even burning. A calibrated brass plate with an engraved dial is attached parallel to the candle.
There is a small metal plate between the candle and the brass plate, which casts a shadow when the candle is lit. If the candle is lit at a certain evening hour, which corresponds to the time of day, the time can be read on the metal sheet while the shadow moves upwards.
This candle from the Saarland Clock Museum can be purchased at the cash register. In a quiet place with no draft, it is quite accurate.