The South German oil lamp clock from the 18th century is a tin oil lamp with a cylindrical glass oil container. There is a pewter measuring tape with Roman numerals on the glass bulb. The time can be read by the drop in the oil level as it burns. These oil clocks were used for a long time. Even when wheel clocks had been around for a long time, the oil clock was still popular and widespread as a timepiece during the night, because you could read the time on it even in the dark.
In contrast to the candle clock, the oil lamp clocks were somewhat less precise, e.g. because of the different qualities of the oil.
