Wheels

                  
Besides fire, many people claim that the biggest invention of mankind was the wheel. Imagine how many trillions of miles are made every hour on four wheels in cars all over the world. Imagine how useful the wheel was when the prehistoric people moved obelisks and huge stones to build massive structures by means of the humble wheel. Just consider the Egyptians building the pyramids with the use of wheels to move huge boulders needed to construct some of the wonders of the world. Wheels are needed when airplanes use the runway to take off to cross from continent to continent, from one airport to another, even from aircraft-carrier to heliports to attack, to fight, but also to bring much needed medicine to poor countries. The wheel-and-axle combination was invented around 4500 BC in Mesopotamia, and was probably first used for a potter’s wheel. Foot-powered spinning wheels appeared around 500 BC, water-wheels in the first century BC and windmills in the seventh century AD. For centuries, waterwheels and windmills helped irrigate fields or remove water from flooded areas; they drove grinding machines to produce flour; they powered bellows and hammers in metal workshops.  During the 17th and 18th centuries, water-wheels powered huge machines in cotton mills. Eventually, the steam engine became the preferred source of power to turn the wheels of industry. Wheels are indispensable to have roller-skates, bicycles, trains, and so much more. This photo was taken when I was in John Day, Oregon, where an antique store had a maintenance facility to fix wheels of old carriages, which are nowadays used only for ceremonial occasions.