Build a water clock

A water clock, or a Clepsydra, is one of the oldest types of clock. It reliably measures time by making water flow at a constant rate and allowing you to measure how much water falls within a certain amount of time.

Equipment

• Plastic bottle with cap

• Water

• Timepiece (stopwatch)

Method

1. Cut the bottle into 2 parts. The top half with the lid should be slightly shorter than the bottom

2. Make a small hole in the lid

3. Put the top part of the bottle inside the bottom part with the lid facing down

4. Fill the top with water

5. Measure how much water falls through the hole in 1 minute and mark this on the side of the bottle

6. Repeat step 5 for 2 and 3 minutes

7. Once you have these markings you can add more by measuring the distance between the existing marks