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Instructions for How to Make an Anemometer

An elementary anemometer is simple to make, so you can easily use your own homemade creation to measure the speed of the wind. While modern, highly calibrated anemometers may have evolved to become more accurate, the basic design is still based on the first anemometers developed in the 1840s. Spinning cups catch the wind and rotate around a stationary pole, and the number of rotations in a given time (usually 10 seconds) indicates the wind speed.

Things You'll Need

2 pieces 1/4-by-1/4-by-12 inch balsa wood
Utility knife
Glue
4 plastic 3-ounce cups
Finishing nail
Hammer
1-inch diameter dowel, 2 feet long
Washer
Marker

Instructions

- 1
  Find the center of a piece of 1/4-by-1/4-by-12 inch balsa wood and use a utility knife to cut a 1/4-inch wide and 1/8-inch deep housing in one side of the balsa wood strip. Repeat on a second piece of 1/4-by-1/4-by-12 inch balsa wood.
- 2
  Wipe a small amount of glue into each housing. Mate the housings on the two pieces of balsa wood, which will form the balsa wood into a cross. Leave to dry for 30 minutes.
- 3
  Make a 1/4-inch hole in the side of four plastic 3-ounce cups, 1/2 inch below the rim.
- 4
  Turn the cups on their sides, and slide one onto the end of each arm of the balsa wood cross, with all the mouths of the cups facing the base of the cup in front of it.
- 5
  Push the cups onto the balsa wood arms until the end of the arms touch the inside of the other side of the cups. Glue the cups in place.
- 6
  Hammer a finishing nail through the glued cross point of the balsa wood. Wriggle the nail a little so that the balsa wood cross with the cups can spin freely around the nail.
- 7
  Place a washer on the end of a 2-foot length of 1-inch diameter dowel, then hammer the end of the finishing nail into the end of the dowel. Ensure that the balsa wood cross still spins freely around the nail.
- 8
  Hold the dowel into the wind and the cups will catch the air and make the cross spin. Mark one cup to distinguish it from the others and count how many times it rotates in 10 seconds. The basic rule is that between two and four spins is 1 mph wind speed, between five and seven spins is 2 mph wind speed and so forth.

Nature