The water clock sits alongside the sundial in history as one of the earliest timekeeping mechanisms invented by mankind. Dating back to approximately 1500 B.C., this type of clock was used by several ancient societies including Egyptians, Greeks and Chinese. Unlike the sundial, the water clock can be used to observe time at night, indoors or in overcast conditions. The basic concept implemented by the water clock is that a set time is required for water to flow from one container to another. Most water clocks consist of a system in which water drips from one elevated container into another.
- Skill level:
- Moderately Easy
Things you need
- Clock or watch
- Paper or plastic cup(s)
- Clear jar
- Large, rectangular piece of cardboard
- Clear tape
- Rectangular strip of paper
Use the thumbtacks to punch a small hole in the bottom of each paper cup. The more paper cups used, the longer it will take for the water to filter to the bottom.
Place the jar and the cardboard on a flat, even surface. Orient the rectangular piece of cardboard so that when it stands, it is taller than it is wide. Stand the cardboard up flush against the side of the clear jar. The bottom of the cardboard should be level with the bottom of the jar. Tape the cardboard to the jar so that the cardboard will stand on its own.
Insert a thumbtack into the side of each paper cup, near the top. Pin the cups to the cardboard so that they face upward, allowing them to hold water. The cups should be aligned one above the other in a straight, vertical line along the length of the cardboard. This will allow water to drip from each cup into the one below it and eventually into the jar. Align the rectangular strip of paper on the jar so that it runs all the way from the top to the bottom. Tape the paper onto the jar.
To ensure the clock works, pour a small amount of water into the top cup and allow it to drip through the entire system. Afterward, pour the water out of the jar and cups.
Fill the top cup with water. If the cup detaches from the cardboard because of the weight of the water, use extra thumbtacks and tape to resecure it.
Use the watch or clock to measure how much time it takes for the water to filter downwards. On the strip of paper, mark the level of the water in the clear jar every minute. If using more than one paper cup, mark the level of the water in the jar every 5 minutes.
After all the water has filtered to the bottom, the clock is complete and can be used to measure short intervals of time according to the marks made on the strip of paper.
Tips and warnings
- Make sure that the hole in each cup is not too large, otherwise the water will flow quickly through the clock, preventing it from measuring any substantial amount of time.
- Because paper cups deteriorate over time, the clock will not last very long. To extend the life of the clock use plastic cups.
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