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 .
Quick Answer. The VS-300, the world's first functioning helicopter, was invented by Igor Sikorsky. The patent was granted to Sikorsky on March 19, 1935, following his initial application on June 27, 1931. Keep Learning.