Today, let's tunnel our way through history. 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.
So much technology expresses basic human urges. We want to fly through the air, communicate with each other, travel about. And I remember, as a small boy, wanting to tunnel -- to hollow a house out of a snow bank, to dig a cavern in the back yard, to explore the huge sandstone caves down along the Mississippi River.
Sure enough, we find that tunneling has drawn one great engineer after another into startling excesses of construction. The ancients were greater tunnelers than most of us realize, and I don't mean just catacombs and crypts. In 525 BC the Greeks cut a six-foot square water supply tunnel, two-thirds of a mile long, on the island of Samos. The Romans connected two towns with the mile-long Posilipo road-tunnel in 36 BC. It was thirty feet wide.
The great civil engineers of the nineteenth century were drawn into really grand tunneling. Two new kinds of transport created a need for tunnels. Railways had to lie on almost flat ground, and so did England's huge canal system. By the early 1800s those canals had become England's primary commercial trade network. Canals and railways, like the Roman aqueducts before them, spawned heroic tunneling through obstacles.
Take Marc Brunel's tunnel under the Thames River: Brunel was first to work in the really soft soil under a river. He began the Thames Tunnel in 1825, and it opened to foot traffic in 1843. During those eighteen years Brunel, and his son Isambard Kingdom Brunel, single-handedly invented the new technology of soft-soil tunneling. They also suffered cave-ins and personal injury. Workers died. In the end, the Brunels bankrupted their company. The tunnel didn't open to train traffic until 1865, forty years after tunneling began. Yet it's still in use today.
The star-crossed Hoosac Tunnel through a mountain in western Massachusetts began as a canal tunnel in 1851. It also turned into a rail tunnel before it was finished in 1876. That 26-foot square, five-mile-long tunnel consumed 199 lives, and it almost bankrupted Massachusetts. But the effort provided all kinds of new tunneling technology. That one gave us the now-common pneumatic drill.
Today those technologies are highly refined, and remarkable tunneling goes on without fanfare. Who's heard of the 85-mile-long Delaware Aqueduct Tunnel, carrying water from the Catskill Mountains to New York City? It was finished in 1942.
Tunnels have evoked amazing engineering. But when I was a boy in cold Minnesota, my favorite tunnel was more modest. It was the one in John Greenleaf Whittier's poem, Snowbound. To get from the farmhouse to the barn after a northern blizzard, Whittier says,
We cut the solid whiteness through
And where the drift was deepest, made
A tunnel walled and overlaid
With dazzling crystal.
I'm John Lienhard, at the University of Houston, where we're interested in the way inventive minds work.
See, e.g., Bobrick, B., Labyrinths of Iron: Subways in History, Myth, Art, Technology, and War. New York: Henry Holt And Company, 1981/1986.
An extensive discussion of these matters is to be found in the Proceedings of the Smithsonian Institution's Symposium on its Tunneling Exhibition, Down Under: Tunnels Past, Present, and Future, at the National Museum of American History, Saturday, October 23, 1993. (These proceedings were still in press at this writing.)
Whittier, J. G., Snow-Bound: A Winter Idyl, New York: The Limited Editions Club, MCMXXX, see especially, pp. 9-10.
This is a revised version of Episode 51. I say more about tunneling as a metaphor in Episodes 58, 664, 849 and 855. For more technical looks at tunneling, go to the Engines SEARCH function, using the word "tunnel".
Representation of a medieval mining
tunnel in Agricola's De Re Metallica, 1556