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 .
The first person to make an engine-powered flight was Henri Giffard who, in 1852, flew 27 kilometres (17 mi) in a steam-powered airship. [9] Airships would develop considerably over the next two decades: In 1863, Dr. Solomon Andrews devised the first fully steerable airship, the Aereon, although it had no motor. [10]