Inca Leapt Canyons With Fiber Bridges

MIT Students Plan to Stretch 60-Foot-Long Fiber Bridge Between Campus Buildings

Conquistadors from Spain came, they saw, and they were astonished. They had never seen anything in Europe like the bridges of Peru. Chroniclers wrote that the Spanish soldiers stood in awe and fear before the spans of braided fiber cables suspended across deep gorges in the Andes, narrow walkways sagging and swaying and looking so frail.

Yet the suspension bridges were familiar and vital links in the vast empire of the Inca, as they had been to Andean cultures for hundreds of years before the arrival of the Spanish in 1532. The people had not developed the stone arch or wheeled vehicles, but they were accomplished in the use of natural fibers for textiles, boats, sling weapons — even keeping inventories by a prewriting system of knots.

So bridges made of fiber ropes, some as thick as a man's torso, were the technological solution to the problem of road building in rugged terrain. By some estimates, at least 200 such suspension bridges spanned river gorges in the 16th century. One of the last of these, over the Apurimac River, inspired Thornton Wilder's novel "The Bridge of San Luis Rey."

Although scholars have studied the Inca road system's importance in forging and controlling the pre-Columbian empire, John A. Ochsendorf of the Massachusetts Institute of Technology here said, "Historians and archaeologists have neglected the role of bridges."

Ochsendorf's research on Inca suspension bridges, begun while he was an undergraduate at Cornell University, illustrates an engineering university's approach to archaeology, combining materials science and experimentation with the traditional fieldwork of observing and dating artifacts. Other universities conduct research in archaeological materials, but it has long been a specialty at MIT.

Students here are introduced to the multidisciplinary investigation of ancient technologies as applied in transforming resources into cultural hallmarks from household pottery to grand pyramids. In a course called "materials in human experience," students are making a 60-foot-long fiber bridge in the Peruvian style. On Saturday, they plan to stretch the bridge across a dry basin between two campus buildings.

In recent years, MIT archaeologists and scientists have joined forces in studies of early Peruvian ceramics, balsa rafts, and metal alloys; Egyptian glass and Roman concrete; and also the casting of bronze bells in Mexico. They discovered that Ecuadoreans, traveling by sea, introduced metallurgy to western Mexico. They even found how Mexicans added bits of morning-glory plants, which contain sulfur, in processing natural rubber into bouncing balls.

"Mexicans discovered vulcanization 3,500 years before Goodyear," said Dorothy Hosler, an MIT professor of archaeology and ancient technology. "The Spanish had never seen anything that bounced like the rubber balls of Mexico."

Heather Lechtman, an archaeologist of ancient technology who helped develop the MIT program, said that in learning "how objects were made, what they were made of and how they were used, we see people making decisions at various stages, and the choices involve engineering as well as culture."

From this perspective, she said, the choices are not always based only on what works well, but also are guided by ideological and aesthetic criteria. In the casting of early Mexican bells, attention was given to their ringing tone and their color; an unusually large amount of arsenic was added to copper to make the bronze shine like silver.

"If people use materials in different ways in different societies, that tells you something about those people," Lechtman said.

In the case of the Peruvian bridges, the builders relied on a technology well suited to the problem and their resources. The Spanish themselves demonstrated how appropriate the Peruvian technique was.

Ochsendorf, a specialist in early architecture and engineering, said the colonial government tried many times to erect European arch bridges across the canyons, and each attempt ended in fiasco until iron and steel were applied to bridge building. The Peruvians, knowing nothing of the arch or iron metallurgy, instead relied on what they knew best, fibers from cotton, grasses, and saplings, and llama and alpaca wool.

The Inca suspension bridges achieved clear spans of at least 150 feet, probably much greater. This was a longer span than any European masonry bridges at the time. The longest Roman bridge in Spain had a maximum span between supports of 95 feet. And none of these European bridges had to stretch across deep canyons.

The Peruvians apparently invented their fiber bridges independently of outside influences, Ochsendorf said, but these bridges were neither the first of their kind in the world nor the inspiration for the modern suspension bridge like the George Washington and Verrazano-Narrows Bridges in New York and the Golden Gate in San Francisco.

In a recent research paper, Ochsendorf wrote: "The Inca were the only ancient American civilization to develop suspension bridges. Similar bridges existed in other mountainous regions of the world, most notably in the Himalayas and in ancient China, where iron chain suspension bridges existed in the 3rd century B.C."

The first of the modern versions was erected in Britain in the late 18th century, the beginning of the Industrial Revolution. The longest one today connects two islands in Japan, with a span of more than 6,000 feet from tower to supporting tower. These bridges are really "hanging roadways," Ochsendorf said, to provide a fairly level surface for wheeled traffic.

In his authoritative 1984 book, "The Inka Road System," John Hyslop, who was an official of the Institute of Andean Research and associated with the American Museum of Natural History, compiled descriptions of the Inca bridges recorded by early travelers.

Garcilasco de la Vega, in 1604, reported on the cable-making techniques. The fibers, he wrote, were braided into ropes of the length necessary for the bridge. Three of these ropes were woven together to make a larger rope, and three of them were again braided to make a still larger rope, and so on. The thick cables were pulled across the river with small ropes and attached to stone abutments on each side.

Did you ever come across this?

http://agutie.homestead.com/files/world_news_map/inca_ancient_calendar_andes.html

On another website I came across this paragraph:

In temples such as the one Benfer uncovered, the Andeans constructed offering chambers, used them for ceremonies and then built new chambers above the old. Benfer said this protected the Buena Vista site from looters, who came within one inch of the musician statuary while searching for gold and silver in the ancient temple. The well-preserved offering chamber holds ancient pieces of cotton and burned twigs, and Benfer’s team used the twigs to radio-carbon-date the various components of the excavation site.

http://www.newswise.com/articles/view/520388/#imagetop

“The well-preserved offering chamber holds ancient pieces of cotton and burned twigs...”

That’s exactly what was found at Caral! Methinks they were quipu - not ‘offerings’ but hidden for safekeeping.

The Quipus and The Royal Commentaries of the Inca

In 1609, the Inca Garcilaso de la Vega published the first volume of his Royal Commentaries of the Incas in Lisbon. He wrote:

The word quipu means both knot or to knot; it was also used for accounts, because they were kept by means of the knots tied in a number of cords of different thicknesses and colors, each one of which had a special significance. Thus, gold was represented by a gold cord, silver by a white one, and fighting men by a red cord.

When their accounts had to do with things that have no color - such as grain and vegetables - they were classified by categories, and, in each category, by order of diminishing size. Thus, to furnish an example, if they had had to count the various types of agricultural production in Spain, they would have started with wheat, then rye, then peas, then beans, and so forth. In the same way, in order to make an inventory of the arms of the imperial army, they first counted the arms that were considered to belong in a superior category, such as lances, then javelins, bows and arrows, hatchets and maces, and lastly, slings, an any other arms that were used. In order to ascertain the number of vassals in the Empire, they started with each village, then with each province: the firs cord showed a census of men over sixty, the second, those between fifty and sixty, the third, those from forty to fifty, and so on, by decades, down to the babes at the breast.

Occasionally other, thinner, cords of the same color, could be seen among one of these series, as though they represented an exception to the rule; thus, for instance, among the figures that concerned the men of such and such an age, all of whom were considered to be married, the thinner cords indicated the number of widowers of the same age, for the year in question: because, as I explained before, population figures, together with those of all the other resources of the Empire, were brought up to date every year.

According to their position, the knots signified units, tens, hundreds, thousands, ten thousands and, exceptionally, hundred thousands, and they were all as well aligned on their different cords as the figures that an accountant sets down, column by column, in his ledger. Indeed, those men, called quipucamayus, who were in charge of the quipus, were exactly that, imperial accountants.

The number of quipucamayus scattered throughout the Empire, was proportional to the size of each place. Thus the smallest villages numbered four, and others twenty, or even thirty. The Incas preferred this arrangement. even in places where one accountant would have sufficed, the idea being that, if several of them kept the same accounts, there was less risk that they would make mistakes.

Every year, an inventory of all the Inca’s possessions was made. Nor was there a single birth or death, a single departure or return of a soldier, in all the Empire, that was not noted on the quipus. And indeed, it may be said that everything that could be counted, was counted in this way, even to battles, diplomatic missions, and royal speeches. But since it was only possible to record numbers in this manner, and not words, the quipucamayus assigned to record ambassadorial missions and speeches, learned them by heart, at the same time that they noted down the numbers, places and dates on their quipus; and thus, from father to son, they transmitted this information to their successors. The speeches exchanged between the Incas and their vassals on important occasions, such as the surrender of a new province, were also transmitted to posterity by the amautas, or philosophers, who summarized them in simple, clear fables, in order that they might be implanted by word of mouth in the memories of all the people from those at court to the inhabitants of the most remote hamlets. The harauicus, or poets, also composed poems based on diplomatic records and royal speeches. These poems were recited for a great victory or festival, and every time a new Inca was knighted.

When the curacas and dignitaries of a province want to know some historical detail concerning their predecessors, they asked these quipucamayus, who were, in other words, not only the accountants, but also the historians of each nation. The result was that the quipucamayus never let their quipus out of their hands, and they kept passing their cords and knots through their fingers so as not to forget the tradition behind all these accounts. In fact, their responsibility was so great and so absorbing, that they were exempted from all tribute as well as from all other kinds of service.

All laws, ordinances, rites, and ceremonies throughout the Empire were recorded by these same means.

When my father’s Indians came to town on Midsummer’s Day to pay their tribute, they brought me the quipus; and the curacas asked my mother to take note of their stories, for they mistrusted the Spaniards, and feared that they would not understand them. I was able to reassure them by re-reading what I had noted down under their dictation, and they used to follow my reading, holding on to their quipus, to be certain of my exactness; this was how I succeeded in learning many things quite as perfectly as did the Indians.

http://agutie.homestead.com/files/Quipu_B.htm

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