The Iron Age was a prehistoric time when useful tools and weapons were first made from iron and steel. The dates this occurred in various parts of the world varies, with historians suggesting around 12th century BC in ancient Greece and 6th century BC in Northern Europe.
His conceptual drawings included plans for musical instruments, war machines, calculators, boats and other ideas. Many of these plans were limited by the level of technology at the time.
Tesla moved his lab to Colorado Springs in 1899 where he proved the Earth was a conductor, produced artificial lightning and became well known to his neighbors with ambitious electrical experiments that caused booming thunder, rogue sparks and the occasional power outage.
His impressive work was described in papers such as 'On Physical Lines of Force', 'A Dynamic Theory of the Electromagnetic Field' and 'A Treatise on Electricity and Magnetism'.