1 Discard any hammer with mushroomed or chipped face or with cracks in the claw or eye sections. 2  Wear safety glasses or goggles, or a face shield (with safety glasses or goggles).  Strike a hammer blow squarely with the striking face parallel to the surface being struck.
The first jet airplane was the Heinkel He 178 made in Germany in 1939, right before the outbreak of World War II .
In 1874, Felix du Temple made the first attempt at manned flight in a powered aircraft. Immediately after the Wright Brothers make their first powered flights in 1903, they begin to develop their experimental aircraft into a marketable product.