I learned four different inventions this week and they are the trebuchet, distilled spirits, vertical windmill, and the stern–mounted rudder. The first invention is the trebuchet. It destroys walls and stays beyond the reach of archers. Its use was reduced through the 1400s. The next invention I learned about is the distilled spirits. Liquors, or spirits, fermented beverages that have encountered distillation. Demand for rum required greater production of sugar cane. The third invention I learned about is the Vertical windmill. It turns wind energy into power. William Kamkwamba built it from junk and became famous. The last invention I learned about is the stern–mounted rudder. It allows big ships to be steered. The rudder let ships go faster than ever before.