Candle

A candle was a stick of wax with a wick that was lit. The flame would gradually use up the wax as it burned, shortening the candle.

Mandrel marked a level on a candle he owned and told the Fourth Doctor he must return from the Consum Bank before it burned that low or he would kill Leela. (DW: The Sun Makers)

Due to the plant's sensitivity, West Yorkshire rhubarb had to have a carefully controlled light source. For this reason, Martin Chisom used candles in his rhubard forcing shed. (ST: Lost in the Wakefield Triangle)