Today, America shies away from a strange prison reform. 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.

P risons are strange places. Are they meant to punish? Are they meant to reform? Or are they merely meant to keep criminals out of our hair for a season? That question rides upon a curious 19th-century machine, the prison treadmill.

Treadmills have been around since antiquity. They let us use our lower body muscles to power pumps and mills. Treadmills came into English jails following a 1779 prison reform act. That act said that prisoners should be given

... labor of the hardest and most servile kind in which drudgery is chiefly required and where the work is little liable to be spoiled by ignorance, neglect, or obstinacy ...

Then Sir William Cubitt, a noted 19th-century civil engineer, offered a solution. He designed a treadmill for English prisons. It's aim was to generate power for mills. It looked like a very wide paddle wheel. Workers held on to a bar and climbed the paddle blades. It was like walking upstairs for hours on end. They had to keep lifting their legs. Gravity gave them no choice.

A typical treadmill shift lasted eight hours. Workers spent 40 percent of that time resting. That's a lot worse than it sounds. It meant raising the lower half of their bodies 11,000 feet per day. And yet, hard as it was, 200 men and women could hardly match the output of one water wheel.

The English put vertical separators between prisoners in 1838. Each was to labor in isolation, repenting his crimes and purifying himself through toil. Those treadmills were still operating in this century. Oscar Wilde, sent to prison for gross indecency in 1895, worked on one. When he came out, he wrote about it in the Ballad of Reading Gaol .

We banged the tins, and bawled the hymns

And sweated on the mill,

But in the heart of every man

Terror was lying still.

Cubitt's treadmill may have originally had a productive purpose. But a pound of coal could soon do the work of five men working all day on a treadmill. And labor-wasting was a serious crime in its own right, in the mind of 19th-century America.

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

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