Easytorecall Science Activities at Home: Hero's Fountain
What is Hero's Fountain?
Hero's Fountain is a machine, or apparatus, which produces a jet of water (the fountain) and is powered by compressed air. It was invented by Hero, or Heron, a first century engineer and mathematician from Alexandria.
How to make Hero's Fountain
What you need:
3 2lt pop bottles, clear
Look carefully at the diagram. The cup, or top of the apparatus, is made by cutting the top from one from one of the plastic bottles. The other 2 bottles are left intact.
You need to connect the bottles and the cup with tubing. One way of doing this is to make holes in the tops of the plastic bottles and push the tube through the holes. It is vitally important that no air can leak through any of the connections, so you must make sure that all connections are air tight. This is where the sealant comes in.
An alternative, and probably less messy, solution is to use rubber stoppers. Unless you buy stoppers with holes already in, you will have to drill holes to allow the tubing to go through. The stoppers you can buy are usually tapered from top to bottom, so measure the diameter of the opening on the bottle to give you an idea of size of stopper you need.
Once you have made all the connections, you need to put water into both the upper and lower bottles. If you have used the bottle caps, you can unscrew them. To get the water flowing, put water into the cup at the top until it covers the tube leading down to the bottom bottle.
What happens next is that water will flow from the cup down to the lower bottle. This has the effect of increasing air pressure in the lower bottle. In order to equalise the pressure, air is pushed from the lower bottle to the upper bottle. This in turn increase the pressure in the upper bottle. The pressure is equalised here by water flowing up the copper tube to form the fountain. (see picture). The process will continue until the water in the upper bottle has been transferred to the lower bottle.
For younger children, this activity demonstrates that air exists and can exert a pressure enough to cause water to flow out of the tube. Also that pressure can be tranmitted through fluids.
If you would like a detailed explanation of Hero's Fountain in relation to these principles, there is a pdf document entitled Magic Fountain from Cornell University Library which you can download.
(If you do not have a pdf reader, we recommend Foxit Reader, a free pdf reader which runs on most Windows platforms and which is very fast. Alternatively you can download Adobe Reader, also free, which will run on Windows, Mac, Linux, Palm and mobiles.)
Hero's Fountain Links
There are other ways to set up Hero's Fountain. Here are links to some of them.
See a demo at the University of Monnesota School of Physicas and Astronomy
Early apparatus at Kenyon College