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 .
On December 17, 1903, Wilbur and Orville Wright made the first sustained, controlled flights in a powered aircraft. Back in Dayton, Ohio, the brothers found they had much to do to perfect their invention. While the 1903 Wright Flyer did indeed fly, it was underpowered and difficult to control.