From sundials to candle clocks to atomic watches humans have always been fascinated with telling time. There are many articles all over the internet discussing the history of telling time but three of the more interesting ways (according to the person writing this blog) are water clocks, candle clocks, and incense clocks. Each one will make you feel grateful for the modern-day clock. Remember if you never want to have to set your watches again that the way to go is with the atomic watch. To learn more about atomic clocks/watches see our previous blog entry, Atomic Clocks: What are They?
According to an article on Wikipedia, a water clock (or clepsydra) uses the flow of water to measure time. There are two types of water clocks: inflow and outflow. In an outflow water clock, a container is filled with water, and the water is drained slowly and evenly out of the container. This container has markings that are used to show the passage of time. As the water leaves the container, an observer can see where the water is level with the lines and tell how much time has passed. An inflow water clock works in basically the same way, except instead of flowing out of the container, the water is filling up the marked container. As the container fills, the observer can see where the water meets the lines and tell how much time has passed.
Water clocks are one of the oldest time-measuring instruments. The bowl-shaped outflow is the simplest form of a water clock and is known to have existed in Babylon, Egypt, and Persia around the 16th century BC. Other regions of the world, including India and China, also have early evidence of water clocks, but the earliest dates are less certain. Some authors, however, claim that water clocks appeared in China as early as 4000 BC.
Some water clock designs were developed independently, and some knowledge was transferred through the spread of trade. These early water clocks were calibrated with a sundial. While never reaching a level of accuracy comparable to today’s standards of timekeeping, the water clock was the most accurate and commonly used timekeeping device for millennia, until it was replaced by more accurate pendulum clocks in 17th-century Europe.
A candle clock is a thin candle with consistently spaced markings that when burned, indicate the passage of periods of time. The candle needs to burn steadily. If it is in a draft, it will burn more quickly so it is placed in a holder which lets you see the marks on the candle yet protects the candle from drafts. While no longer used today, candle clocks provided an effective way to tell time indoors, at night, or on a cloudy day.
The earliest known reference comes from a poem written in 520 AD by a guy named You Jiangu. His clock consisted of 6 candles: 12 inches high. Each candle was divided into 12 equal sections, with each section burning for a total of 20 minutes. The entire candle took a total of 4 hours to burn completely.
The most famous candle clock is probably the one made by the Turkish scholar and inventor, Al-Jazari (1136–1206). The Clock of the Swordsman is still the most complex candle clock ever made. In simple terms, it went like this: When an hour passed, a burning candle released a metal ball into a sling on the swordsman’s arm. The weight of it then moved the arm causing the sword to trim the wick. From there the ball dropped into a falcon at the base, which served as a gong to tell the hour.
According to Wikipedia, the incense clock is an Indian timekeeping device that was popularized by China during the Song Dynasty (960-1279) and spread to neighboring East Asian countries such as Japan and Korea. The clocks’ bodies are effectively specialized censers that hold incense sticks or powdered incense that have been manufactured and calibrated to a known rate of combustion, used to measure minutes, hours, or days.
An article from Medium states that the simplest version is nothing more than a specially prepared punk cord with knots at measured intervals. Punk, which is made from decayed wood or fungi, has a steady burning rate making it possible to evenly indicate the passage of time. The poorer classes found a unique way of turning these simple clocks into alarms. The cord was placed near the skin, usually between the toes. Obviously, when the cord burned down to the skin, it was pretty hard to sleep through.
Incense sticks could be used in the same manner. The most common was a stick of sandalwood and elm root that was ground into a powder and mixed with wood dust. This was then turned into a paste and formed into sticks six or seven inches long. Once the stick was dry, its even burning made it an excellent way to keep track of time as well as providing a nice, pleasant scent. Fancier versions of this placed the incense in the body of a dragon made of wood or bronze. If the owner needed to wake up at a specific time, he or she simply placed a thin silk string along the top of the incense. a bell or piece of metal was attached to the other end. When the incense burned down to the chosen point, the bell dropped onto a copper or brass plate. Similarly, balls could be placed at regular intervals to cause a clang every hour.