Engines of Our Ingenuity

No. 2154:

by John H. Lienhard

Today, we take more than salt from a mine. 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.

We/re told that salt seasons all things, that we must eat a peck of salt together before we're real friends. Salt is the stuff of tears, or of scorn. If we live good lives, we're the salt of the earth. Salt is so important. Tribes that live largely on milk and roasted meat have less need to supplement it. But, with our grain-based diets, we do need extra salt. Nobility sits "above the salt" because precious salt was served only on the upper tables. The Bible calls a serious promise "a covenant of salt."

Most salt comes from one of two sources. The ocean holds a mixture of sodium chloride and other less palatable salts. Each comes out of solution at a different stage of evaporation, so we can extract usable table salt from the ocean.

But rock salt is much purer. It's either processed from brines that form when ground water flows through underground salt, or this high-grade "salt of the earth" is mined directly.

Wieliczka salt A huge natural deposit of rock salt lies outside the old Polish capital of Krakow in the town of Wieliczka. Its name is from a Polish phrase, "The Great Salt Treasure." We know that salt was first taken out of Wieliczka's saline springs as early as 3500 BC. When Poland became a nation in the 10th century, the springs were already a major salt center. Then, in the late 13th century, the Poles began mining to get at rock salt, and its brine. For a while salt was Poland's major natural resource.

The Wieliczka mine is still in use today, and it's a marvel. It reaches a thousand feet into the earth, with nearly two hundred miles of tunnels. Those tunnels spoke to the miners' imaginations. We find statues and tableaux carved from the living salt. Kings, trolls, and saints loom out of the darkness, larger than life. Chapels, hewn in the salt, range from small prayer stations to a cathedral lit by crystal chandeliers. One great room is two hundred feet high, and its floor opens onto a lake of brine.

In 1944, the Germans used a part of the mine to assemble airplane engines [possibly for the Heinkel 162], safe from allied bombs. They dismantled that plant when the Russian army approached, and they shipped the workers off to Auschwitz. Only two young Jewish slave laborers managed to hide in the labyrinth until Poles rescued them.

A large sanatorium is now located deep in the mine. There, respiratory patients breathe in the cool salt air. Seven hundred years of technique is on display in a great museum of mining technology. The mine even has its own post office.

Wieliczka is a monument, not just to human ingenuity, but to the symbolic power of the salt of the earth. It's become a celebration of seemingly unlimited imagination. Here that imagination has been fueled by a remarkably unexpected oasis of beauty, both natural and man-made. By the time one leaves this strange fairyland, the open air seems drab by comparison.

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

(Theme music)

Wieliczka Solny Skarb, (Krakow: Krajowa Agencja Wydawnicza, 1984).

Here are some good websites dealing with the Wieliczka mine and museum:

For a geological perspective on the mine, see: D. Hallett, The Wieliczka Salt Mine. Geology Today, Vol. 18, No. 5, Sept-Oct 2003, pp. 182-185.

This is a greatly revised version of Episode 297. I also say more about tunneling and the underground in several episodes. See, e.g., Episodes 849, 850, 855, and 1388.
Wieliczka salt mine
Nineteenth-century woodcut image of the Wieliczka salt mine

The Engines of Our Ingenuity is Copyright © 1988-2006 by John H. Lienhard.