Make It · Book Two

Siphon

The Roost's water ran uphill for two miles and then downhill into a tank, with no pump and no power at all — and then one morning it ran backwards. Here is the whole trick, on a table, in ten minutes.

Ink drawing of the finished build.
The finished thing, drawn the way the books draw an object.

You need

  • two jars
  • a book to stand one on
  • about two feet of clear plastic tube that has never been used for anything else
  • a tray
  • and clean water

About half an hour. Everything on that list came out of a kitchen, which is the rule these pages are written to.

Steps

  1. Put the tray down first. All of this is wet.
  2. Fill one jar three-quarters. Stand it on the book so it is higher than the other jar.
  3. Put the empty jar on the tray, lower down.
  4. Prime the tube. Hold the whole tube under the water in the full jar until every last bubble is out of it. This is the part that matters and the part everybody rushes.
  5. Pinch both ends shut with your fingers, under water.
  6. Leave one end down in the high jar. Put the other end in the low jar. Let go of the low end first.
  7. Water climbs up out of the high jar, over the lip, and pours into the low one, and keeps going by itself until the high jar is empty.
  8. Now break it on purpose. Lift the high end out of the water for one second and put it back. The water stops, and it will not start again however long you wait. That is what happened to the Roost, and it is why Nell had to walk two miles.
  9. Try it wrong. Prime it but leave one bubble in the middle, and see how far it gets. Then set the two jars almost level. Write down the smallest difference in height that still works, in fingers.

Rules — read these before step one

  • Never start a siphon with your mouth. Not once, not to see whether it works. That is what step 4 is for.
  • Clean water only. Not juice, not soap, not anything out of a bottle from under a sink, ever. If you would not drink it, it does not go in the tube.
  • Keep the tube short — under three feet — and use one that has never held anything else. Wash it afterwards and hang it up to dry.
  • Work over the tray, on a low table, nowhere near a plug, a lamp or a cord.
  • Wipe the floor when you are finished. A wet floor is the only way anybody has ever been hurt doing this, and it is worth not being the first.