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No. 24:
The Wheel and the Crank

Today, let's reinvent the wheel. The University of Houston's College of Engineering presents this series about the machines that make our civilization run, and the people whose ingenuity created them.

As nearly as we can tell from archaeological evidence, the wheel was invented somewhere in present-day Iraq or Iran around 3500 BC. That in itself is suprising, because it's so late in human history. The other odd thing about the wheel is that it stayed within Europe and Asia as long as it did. Wheels were hardly seen in the American hemisphere until they were brought into regular use by European settlers in the 17th century. There's evidence that 11th-century Mexicans had the concept, but no evidence of its general use.

Of course, we've lived since birth with a hundred thousand different forms of the wheel. It's hard for us to imagine what a difficult concept it represents. But look at it, if you can, from the standpoint of someone who's never seen one. You understand movement in a straight line, and you understand the idea of turning things around. But can you make a connection between the two? Can you conceive of making a vehicle go forward by turning something around?

We've all played the children's game of patting our head and rubbing our stomach at the same time. It's very hard to do, because it's hard to conceptualize these two very different kinds of motion at the same time.

The conceptual difficulties of the wheel are compounded if we move to a variation of the idea -- if we move to the hand crank. The crank is another very common device that you might think had been with us since the dawn of history, but it has not. The hand crank has been in general use for only a thousand years. The Greeks didn't have it. The Egyptians didn't have it. The vaunted Romans with their much-praised technology never arrived at this seemingly simple device.

The hand crank, of course, takes the problem of converting back-and-forth motion of our upper arm into a rotational motion, and it freezes this transformation into one location. In a sense, it requires that we solve the problem of patting our head and rubbing our stomach at the same time.

Most of the important ancient inventions seem to have been made over and over -- at different times and in different places. Not so the wheel. It seems to have originated in one place and diffused to other peoples and other cultures from there. It was very likely the product of an isolated act of human ingenuity.

I'm John Lienhard at the University of Houston, where we're interested in the way inventive minds work.

(Theme music)

Childe, V. G., Rotary Motion, A History of Technology. Vol. I, (C. Singer, E. J. Holmyard, A. R. Hall, and T. I. Williams, eds.) New York: Oxford University Press, 1956, Chapter 9.

White, L., Jr., Medieval Technology and Social Change. New York: Oxford University Press, 1966, Chapter

For another look at the problems inherent in inventing the wheel, see Episode 1254.