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 .
Introduction. On December 17, 1903, Wilbur and Orville Wright successfully flew the first heavier-than-air, powered aircraft. Although they had tested their theories about air travel with non-powered kites and gliders, this date marked the first time for an engine-powered flight.