Oil-lamp clocks are
clocks consisting of a graduated
glass reservoir to hold oil - usually
whale oil, which burned cleanly and evenly - supplying the fuel for a built-in lamp. As the level in the reservoir dropped, it provided a rough measure of the passage of
time.
The principle behind such a time-keeping device is that it measures a quantity that either decreases or increases at a constant rate. Lamps or candles, burning fuel at a steady pace, fit this category, and as a bonus produce useful light. Hourglasses depend on the steady draining of fine sand through a small aperture.
Water clocks
A water clock or clepsydra (; ; ) is a timepiece by which time is measured by the regulated flow of liquid into (inflow type) or out from (outflow type) a vessel, and where the amount is then measured.
Water clocks are one of the oldest time-m ...
or clepsydra measure a gain or loss of water by using drops of uniform size and frequency. The Persian fenjaan made use of the constant time it took for the sinking of a floating bowl with a hole in its underside.
It is unknown when or where the oil-lamp clock was first introduced. This clock was mainly used during the mid-18th century.
See also
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Candle clock
A candle clock is a thin candle with consistently spaced marking that, when burned, indicates the passage of periods of time. While no longer used today, candle clocks provided an effective way to tell time indoors, at night, or on a cloudy day.
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Water clock
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Hourglass
An hourglass (or sandglass, sand timer, sand clock or egg timer) is a device used to measure the passage of time. It comprises two glass bulbs connected vertically by a narrow neck that allows a regulated flow of a substance (historically sand) ...
References
Clocks
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