The wheel is one of the most fundamental inventions we use in our everyday lives. Invented sometime around 3500 BCE, during the Chalcolithic era, the wheel gave rise to everything from transportation to modern-day machinery and almost everything in between.
The wheel on its own, while promising, is not very useful. Much like a doughnut, its most important feature is the hole in the center. If it wasn't suitable for attaching a stable platform by combining it with an axle, the wheel would be nothing but a cylinder rolling on its edge. By the time the wheel and axle were invented, it was the Bronze Age. Casting metal alloys, constructing canals and sailboats, and complex musical instruments such as harps all predate the wheel and axle.
The idea of adding an axle isn't a simple one
For the system to work, the wheel must rotate freely around the axle. This is achieved by fitting the axle directly in the center of the wheel to maximize continuity during motion. In addition, the axle and the whole alignment must be perpendicular, to reduce friction. Furthermore, the axle should remain as thin as possible to reduce its surface area while still being able to support the load.
From here, the only friction to overcome is that between the inner wheel and the axle. The smoother the inner surface of the wheel, and the outer surface of the axle, the less friction the system has to overcome.
The success of the whole structure was also sensitive to the size of the axle. A thick axle would generate too much friction, while a narrow one would reduce friction but would also be too weak to support a load. To solve this problem, the earliest wagons were small and narrow, so they could have short, thin axles.
Not only do all these parameters have to be met for this structure to work, but all at the same time. It may be for this reason that such a simple concept took so long to gain traction.
Archaeologists argue that another limiting factor was the need to carve wood for the wheel and axle very precisely. For this, metal tools would have been necessary — which perhaps explains why the wheel and axle were not invented until after cast copper chisels and gouges became common.
The complex number of factors that had to be overcome in order to make the wheel and axle work meant that it could not have been developed in phases. It had to come all at once. In fact, many archaeologists believe that the wheel and axle were only invented once, in one place, and spread from there.
We are not really sure when or where the wheel originated
Where the wheel and axle originated is a mystery, but its use spread throughout Eurasia and the Middle East rapidly. Some of the earliest images of wheeled carts have surfaced in Poland, suggesting the region may have seen some of its first use.
Asko Parpola, an Indologist at the University of Helsinki in Finland, suggests that the wheel originated with the Tripolye people of modern-day Ukraine. This is based on the fact that the word 'wheel' is derived from their language.
There is evidence to suggest that the earliest use of the wheel may have been in potter's wheels in Mesopotamia, 300 years before it was adapted to fit the chariot.
The wheelbarrow, however, is believed to have first appeared in ancient Greece between 600 - 400 BCE. China followed sometime later and the wheel and axle eventually found their way to medieval Europe. Although the wheelbarrow was a high-priced commodity at the time, it would pay for itself within a few days, as it greatly increased the amount of work that could be done by a single worker.
Archaeologists in Vera Cruz, Mexico, unearthed ceramic toys in the form of little animals. The animals were fitted with wheels instead of legs, so children could push them along. However, the region did not utilize the wheel for transportation until the arrival of the European settlers. This may have been to do with the terrain, however, rather than a lack of know-how.
In the Middle East and North Africa, where there are vast areas of desert, the camel was still the preferred mode of transport, right up until 600 A.D. This could be because camels tended not to sink or get stuck in the sand, while thin wooden wheels did. Richard Bulliet gives several other possible reasons in his 1975 book, The Camel and the Wheel. Middle Eastern societies did make use of wheels for practices such as irrigation, milling, and pottery.
It is not surprising that after all of this, the basic design of something as robust as the wheel and axle hasn't changed in over 6000 years.
What were the early uses of the wheel?
As we mentioned, wheels were not at first used for transportation. Early wheels consisted of a wooden disk and hole for the axle did play a vital role in early societies. They were commonly used for pottery, irrigation, and milling. It took hundreds of years for the wheel to make its way onto the first chariots.
No wheels exist in nature
When is the last time that you saw a wheel in nature? Many of the world's most life-changing inventions were directly inspired by nature. From the fork to the airplane and velcro, many technologies involve some form of biomimicry. Except for the wheel. It is one hundred percent homo sapien innovation.
However, some argue that the idea of the wheel does appear in nature. One example can be found in Dung Beetles. Dung beetles lay their eggs in dung (which serves as food for the larvae) and transport them by rolling the dung into a ball. Other potential inspirations, according to Michael LaBarbera — a professor of biology and anatomy at the University of Chicago — include “wheeled organisms” and tumbleweeds.
"Wheel of Fortune" is more than just a game show
The wheel of fortune is not just an American television game show. In fact, it is a concept in medieval philosophy that symbolizes fate. The wheel belongs to the goddess Fortuna who spins the wheel to decide the fates and misfortunes of mortals. Fortuna is often depicted as a blindfolded woman spinning a giant wheel.
The most common design for a perpetual motion device is the overbalanced wheel
The concept of perpetual motion machines has been around for centuries. It is the holy grail of science, and if it were to be achieved, it would produce free energy once it is set in motion. Perhaps the most famous example is Bhāskara's wheel. Invented in 1150 by Bhāskara II, an Indian mathematician, the wheel-machine was an attempt to create a perpetual-motion machine. The wheel consisted of curved or tilted spokes partially filled with mercury.
The mercury was intended to shift mass to a larger radius from the wheel's axle, unbalancing the wheel to sustain rotation in one direction. In the end though, friction and entropy do their work and the motion slows and then stops.
Using wheels to create optical illusions
There is a concept in film called aliasing. This is when a rotating wheel is illuminated by flickering light so that it appears to be spinning. Film cameras work by capturing a series of still images, they then play these images in sequence at roughly 50 frames per second. This is enough to fool our brains into thinking that the image is moving. However, if the wheel is moving faster than the frame rate, the rotation surpasses the image capturing frequency and the wheel appears to be moving backwards.
For example: If a spoke of the wheel is at the 12 o'clock position in the first frame, and then in the second frame that spoke moves almost a full rotation to the 11 o'clock position. Your brain will interpret that as moving anti-clockwise as it cannot determine what is happening between frames. At the right frequency, a strobe light or even a fluorescent lamp can have the same effect.
Ever wondered where the term fifth wheel comes from?
A fifth wheel was one that extended from the front axle of a carriage to prevent it from tipping over. Much like a drag racer has on its rear. Most of the time it was never used and landed up being redundant, hence, by calling someone or something 'a fifth wheel' you are referring to them as unnecessary.