How to Build a Water Powered Clock

Large water powered clock with actual clock face

Water clocks are among the most ancient timekeeping devices. They were used by both the Ancient Egyptians and Greeks. The Greeks gave the water clock the name "clepsydra," or "water thief." Water drains from a vessel at a fixed rate of speed. The vessel is marked to show the hours of the day. As the vessel empties, the time is shown by the level of the water. Water powered clocks use gravity as their sole source of energy.

Things You'll Need

• 1 quart plastic container
• Plastic cocktail straw
• Small nail, same diameter as straw
• Hammer
• Scissors
• Masking tape
• Small stand or box, approx. six inches tall
• Large bowl, 1 quart or greater capacity
• Water
• Clock or watch
• Marking pen
• Ruler

Instructions

1. Lay the plastic bottle on its side. This will be the main vessel of the water powered clock. Take the small nail and place the point approximately one inch from the bottom of the bottle. Use the hammer to gently drive the nail through the side of the bottle. The nail must not go all the way through to the other side of the bottle.

2. Use the scissors to trim a piece of masking tape to the exact length of the bottle from just below the mouth to the bottom of the bottle. Attach the tape to the side of the bottle opposite the nail hole. The tape should extend as far up the bottle as it is reasonable to fill the bottle.

3. Push one end of the cocktail straw into the nail hole. The end of the straw should extend about one inch into the water clock bottle. Place the bottle upright on the small stand or box, and as close to one edge as possible. The cocktail straw will stick out a few inches over the edge of the stand. Place the bowl directly underneath the cocktail straw.

4. Fill the bottle of the water powered clock with water. Place your finger on the end of the cocktail straw to prevent water from seeping out. Keep filling until the water has reached exactly to the top of the masking tape. Remove your finger from the end of the cocktail straw.

5. Note the exact time that the water begins to flow out of the water powered clock. After exactly five minutes, use the marking pen to make a small mark on the masking tape at the current water height. Use the ruler to measure the exact distance from the top of the masking tape to the mark. Record this length of time.

6. Continue to mark the masking tape until it reaches about halfway across the width of the tape. Write the number "5" next to it on the tape. Using the ruler as a guide, make similar markings at five-minute intervals down the full length of the tape. The distance between each mark should be exactly the same as the distance between the top of the masking top and the first five-minute mark. Label each new mark sequentially as "10," "15," "20," etc.

Tips & Warnings

• The amount of time that can be recorded by the water powered clock will vary in accordance with the size of the bottle and the width of the straw. The greater the amount of time recorded by the water clock, the higher the numbers on the masking tape.

• In marking the water clock, the bottle can be emptied first, then the tape marked while the bottle is empty.

• The water powered clock bottle must not have tapering sides. The bottle must be of even shape to permit the water to flow evenly down through the bottle.

References

• A Walk Through Time: Water Clocks
• Science Net Links: Building a Water Clock
• Newton's Apple: Water Clock

Resources

• Clepsydra Water Clock