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MIT Students Show How the Inca Leapt Canyons
PCOL writes "When Conquistadors came to Peru from Spain in 1532, they were astonished to see Inca suspension bridges achieve clear spans of at least 150 feet at a time when the longest Roman bridge in Spain had a maximum span of 95 feet. The bridges swayed under the weight of traffic terrifying the Spanish and their horses, even though, as one Spaniard observed, they were almost as "sturdy as the street of Seville." To build the bridges, thick cables were pulled across a river with small ropes and attached to stone abutments on each side. Three of the big cables served as the floor of the bridge, two others served as handrails and pieces of wood were tied to the cable floor before the floor was strewn with branches to give firm footing for beasts of burden. Earlier this year students at MIT built a 70-foot fiber bridge in the style of the Incan Empire. The project used sisal twine from the Yucatan Peninsula and anchored it by wrapping it around massive concrete blocks. The weekend's burst of activity was preceded by 360 hours of rope-twisting as the 50 miles of sisal twine was turned into rope. Working together as a group was part of the exercise. "A third of the time was spent learning to work together," one of the students said. "But after a while, we were banging those cables out.""
People here seem to be missing the point - it isn't that this stuff isn't trivial compared to todays engineering, it is. But it's more revealing about the fact that non-western civilizations had an advanced grasp of the physics/science behind this stuff. They knew how to take advantage of rope tension. A bridge like this isn't so impressive today. It's easy to build. But to come up with the design is the hard part.
Oh man, it wasn't pretty. My hands are pretty worn in from working on cars and in machine shops a lot of the time but they were always sore and red after a night of twisting. Sometimes I wore my mechanix gloves, but they don't give the feel really needed to work it fast.
You gotta find first gear in your giant robot car
Not on purpose as far as I remember, but when the rope reached a certain size it couldn't just be reeled up by hand anymore and we had to have two people act as a reel, twisting the rope around themselves as they walked down the hall. Eventually they'd be tied right up against each other with something like 70lb of rope around them.
You gotta find first gear in your giant robot car
The Aztecs were in and around the region of Mexico, the Incas were in South America roughly where Peru is today. The ones who had died out were the Maya, although there were several small tribes in Central America (Chorotega, Guatuso, etc) between the two mighty empires.
Seven puppies were harmed during the making of this post.
1) Aztec Empire, Mexico, Cortez, 1519-1521.
2) Incan Empire, Peru, Pizarro, 1532-1535 (occasional resistance until 1570 or so)
3) Mayan Empire, Mexico, was more of a federation of cities, First contact in 1517, a couple failed expeditions 1527-1535, success in 1540-1546 (last city only conquered in 1697 though)
The descendants of the original bridge builders still do this each year at one of the original sites, using techniques handed down by previous generations. Photos here:
http://en.wikipedia.org/wiki/Inca_rope_bridge#Renewing_the_last_bridge
The deal with the concrete blocks was that they were provided to us quite cheaply by one of the companies doing construction at Sloan. They brought them in, put them where we told them to, and took them back when we were done so we couldn't do much to them. Without them stacked up like that it would have been horribly difficult to get the normal force required on the brick surrounding the Stata center (which of course we couldn't even think about touching).
About the sign, we assumed it would be wholly ignored. We needed it to satisfy the safety office I think (I wasn't involved with that end of the planning much).
You gotta find first gear in your giant robot car
Because the higher, the fewer.
Slashdot gets worse every day... Pipedot: News for nerds, without the corporate slant
Maybe describing it in a context that any Slashdotter would understand might help.
Aztecs:
I, for one, welcome our Mesoamerican, Cortez-hating, Virgin of Guadalupe-worshiping, human-sacrificing, maize-and-bean-growing, empire-building Mexica overlords.
Incas:
I, for one, welcome our pre-Columbian, sun-loving-with-bare-titicas, Conquistador-fighting, Machu-Picchu coca leaf-chewing, Andean-whistling and bridge-building overlords.
Back in 1997 NOVA did an episode, "Secrets of Lost Empires: Inca", where they went to Peru and filmed the natives building a grass suspension bridge in the traditional style. I'd recommend watching it if you want to see one of these things under construction, it really it amazing how they go from dry grass to a sturdy rope bridge.
These aren't suspension bridges, as the comparison to the George Washington bridge in the article clearly shows. They are rope bridges.
The difference is that the walking surface is not suspended from the overhead cables. It is instead supported by tension in the ropes that compose it.
The critical difference from the MIT bridge and the monkey bridges many of us made in the scouts is that it was supported by concrete blocks instead of lashed wooden A-frames and stakes. And that the MIT students put a rather impressive number of hours into making and thoroughly vetting their own rope and design.
Can you be Even More Awesome?!
The Maya hadn't died out. Quite the contrary, there were (and are) huge populations of Mayan people in Yucatan and Guatemala. They just weren't the dominant civilization at the time the Spanish arrived. There were probably about a million "Mayans" (exact numbers being impossible to come by for many reasons) while Central Mexico may have had as many as 25 million people (most estimates put it in the 10-15 million range).