As the lamp burns, the oil level descends and passes marks on the glass reservoir. The shape of the glass container makes this timekeeping method inaccurate because the height of the burning oil does not fall at a constant speed.
As the lamp burns, the oil level descends and passes marks on the glass reservoir. The shape of the glass container makes this timekeeping method inaccurate because the height of the burning oil does not fall at a constant speed.