Before the invention of electronic devices, people used to tell time using water clocks, devices consisting of containers with lines and small drainage holes.
Nowadays, keeping track of time seems obvious. People only need to glance at their watch or cell phone to know the time, even down to the second. But before the invention of such battery-powered devices, time tracking was completely different.
For example, in ancient times, sundials were commonly used. However, this method of measuring time has limitations. Sundials only work when there is sunlight and cannot maintain continuous divisions of time. To compensate for these shortcomings, water meters were invented.
There are two types of water meters: outflow and inflow. With the water meter flowing, inside the container mark the measuring lines. The tank is filled with water and gradually leaks out at a steady rate. Observers can tell the time through changing water levels. Inflow water meters operate on the same principle, that is, water drips steadily. However, the measuring lines are in the second container. Based on the amount of water dripping from the first bucket, the ancients could tell how much time had passed.
The oldest water clock with authentic evidence exists from around 1417 – 1379 BC, during the reign of pharaoh Amenhotep III, used in the temple of Amen-Re in Karnak. Meanwhile, the earliest mention of a water clock was in an inscription in the tomb of an official from the 16th century BC in Egypt.
When discovered, the Karnak water meter was broken into many pieces. This artifact is made of plaster, designed like a large flower pot, with characteristic drawings arranged in three horizontal rows on the outside and the image of King Amenhotep III. The water clock has 12 carved columns with 11 equally spaced lines, symbolizing the hours of the night. Water flows through a small hole in the middle of the bottom. To know the time, ancient people would look inside the clock, observe the water level and determine the time based on the nearest line.
However, water meters also have some disadvantages. First, a constant water pressure is needed to keep the water flowing at a constant rate. To solve this problem, the meter draws water from a large tank, in which the water is kept at a constant level.
Another problem is that the length of day and night changes with the seasons, so clocks need to be calibrated every month. The ancients applied a number of measures to solve this problem. For example, a disc with 365 holes of different sizes is used to regulate the flow of water. The largest hole corresponds to the winter solstice, when the day is shortest, and the smallest hole corresponds to the longest day of the year – the summer solstice. These two holes are located at opposite ends of the disc, the other holes are arranged in the middle with increasing or decreasing size. The holes correspond to the days of the year and will be rotated at the end of each day.
Although the basic principle of water clocks is relatively simple, ancient people still faced a number of challenges related to water pressure and changing seasons, causing this type of clock to become increasingly complex. Compared to the ease of telling the time today, it seems that humanity has come a very long way of development.