The Boy Who Harnessed the Wind: Chapter 12 Summary & Analysis

The windmill only works when the wind is blowing, so William begins searching for a battery to save up power. Meanwhile, he puts the windmill to new uses by helping his cousin Ruth charge her cell phone. Ruth is from the larger town of Mzuzu and always bothers William to take her phone to the trading center to charge while she is visiting her father Socrates. Men in the trading center have charging stations with high rates for charging phones, or even using phones, photocopiers, or electric typewriters on the street. However, William needs to force his windmill to produce more power to charge a phone than he usually needs to power a lightbulb.

William needs a step-up transformer to create more energy from the electricity his windmill creates, like those that are used in power companies all over America and Europe. A step-up transformer passes a current between two wire coils until the current is much stronger than it was originally. Using a diagram from Explaining Physics, William makes his own step-up transformer by wrapping wire around an iron sheet with E-shaped prongs, and he is able to boost his windmill enough to charge Ruth’s phone. William also makes electrical sockets for his walls out of old radio plugs and sets up a small business charging phones for others in the village.

After two months, William finally buys a car battery from Charity, who says it “fell off a truck.” To charge the battery, William has to convert his windmill’s AC power to DC power by using a diode from an old radio. With the battery working, William can light his whole house using parallel circuits after he finds lightbulbs that can run using DC power. William even creates light switches out of PVC pipe and circles of material from a flip-flop. Trywell is incredibly proud of the Kamkwambas’ house powered by free electricity, and even prouder that his son built it all.

Having light in the house is definitely a benefit for the Kamkwambas, but it comes with risks. William was forced to use wire he found in the trash or the scrap yard, meaning that most had lost their plastic insulation and could potentially start a fire. Worse, the Kamkwambas’ roof is infested with termites whose chewing might cause all the wires to come crashing down on the Kamkwambas’ heads. One afternoon, termites do break through the roof in William’s room and William has to call in the chickens to eat all the squirming bugs. In all the commotion, William doesn’t notice that the wires cross and spark, but luckily the wires are so cheap that they simply melt and break instead of starting a fire.

William starts to build a proper wiring system using diagrams from Explaining Physics. He needs a circuit breaker that will stop the power if too much current comes at once so that the wires in the house don’t melt. With no way to make normal circuit breaker fuses, William makes an electric bell system using nails and a bar magnet that would cut off the power to the house if the current was ever too large. Two weeks later, William’s circuit breaker is tested by a cyclone. The huge winds overload the windmill, but the circuit breaker trips and keeps the power from reaching the wires in the house. William is happy his invention worked, but Geoffrey tells him he should fix his roof.

Another problem with William’s windmill is the small bike chain that often snaps when the wind blows too hard. William has to go up the tower and fix it, risking injury to his hands from the sharp tractor fan and spinning metal blades. He uses a small piece of rubber bicycle tire to grab the jagged bicycle sprocket and stop the blades from spinning while he fixes the chain, but the sprocket often slices William’s hands.

During this time, Geoffrey continues to work with Uncle Musaiwale in a maize mill the next town over. Geoffrey advises William to get a rubber belt like the ones used in the maize mill to replace the troublesome bicycle chain on the windmill. William finds pulleys in the scrap yard and asks Mister Godsten to weld them to the windmill’s shock absorber (as well as grind down the sharp teeth of the sprocket) so that they can hold the belt in place. But William still needs a real rubber belt. William uses various problematic fixes until Geoffrey brings back a real belt from the maize mill. Finally, William can leave his windmill to do its job without his constant work troubleshooting the various jury-rigged pieces.