The wheel is everywhere on all our
cars, trains, planes, machines, wagons, and most factory and farm equipment.
What could we move without wheels? But as important as the wheel is as
an invention, we don't know who exactly made the first wheel. The oldest
wheel found in archeological excavations was discovered in what was Mesopotamia
and is believed to be over fifty-five hundred years old.
The following steps and developments
took place to invent a functioning wheel, more or less in this order:
Humans realized that heavy objects
could be moved easier if something round (e.g. a tree log) was placed
under it and the object rolled over it.
Humans also realized a way to move
heavy objects, with an invention archeologists call the sledge.
Logs or sticks were placed under an object and used to drag the heavy object,
like a sled and a wedge put together.
Humans thought to use the round
logs and a sledge together.
Humans used several logs or rollers
in a row, dragging the sledge over one roller to the next.
With time the sledges started to
wear grooves into the rollers and humans noticed that the grooved
rollers actually worked better, carrying the object further. This was simple
physics, if the grooves had a smaller circumference than the unworn parts
of the roller, then dragging the sledge in the grooves required less energy
to create a turning motion but created a greater distance covered when
the larger part of the log roller turned.
The log roller was becoming a wheel,
humans cut away the wood between the two inner grooves to create what is
called an axle.
Wooden pegs were used to fix the
sledge, so that when it rested on the rollers it did not move, but allowed
the axle to turn in-between the pegs, the axle and wheels now created all
the movement. These were the first carts.
Improvements to the cart
were made. The pegs were replaced with holes carved into the cart frame,
the axle was placed through the hole. This made it necessary for the larger
wheels and thinner axle to be separate pieces. The wheels were attached
to both sides of the axle.
Next. the fixed axle was
invented, where the axle does not turn but is solidly connected to the
cart frame. Only the wheels did the revolving by being fitted onto the
axle in a way that allowed the wheels to rotate. Fixed axles made for stable
carts that could turn corners better. By this time the wheel can be considered
a complete invention.
The rest is history...