For many people with bad vision, glasses or contact lenses are an essential part of daily life. Without help from these lenses, short-sighted people might be tripping over everything and […]
The helicopter was invented by the Chinese in the 4th century, more than a 1,000 years before Leonardo da Vinci. It was called the Bamboo Dragonfly and could fly 25 feet (7.6 m) up and down. The first modern helicopter was invented by the French.