RETROSPECT String Theory By George Dyson

High-tensile fastenings stand the test of time.

Lashing and sewing, among the oldest of technologies, remain competitive with the best. String was not invented — it was discovered: as vines hanging in the tropical jungle, sinews exposed when carcasses were scavenged in the savannah, tendons and baleen fibers appropriated by arctic hunters who took sea mammals apart. Net making is even older: witness the highly evolved spider’s web.

The puzzle is not why did human beings start lashing things together, but why did they stop? We still sew our clothing, sails, and tents, and our surgeons still sew us, but we no longer sew or lash much else. The few exceptions — like the carbon-fiber skeleton of the Gossamer Albatross, Paul MacCready’s human-powered aircraft that crossed the English Channel in 1979 — are rare. Ironworkers still assemble the steel backbone of our reinforced-concrete-based civilization with tie-wire, but these temporary lashings are quickly covered by cement. Anything that is lashed together is dismissed as jury-rigged or haywire, makeshift at best. We only tie things together after they break. Lashing survives on the front line of emergency repairs, not because it is primitive, but because it handles loads — especially the sudden loads that break things — so well.

“In pure strength, apart from their flexibility, the lashings, sewings, and bindings used by primitive peoples, and by seamen down to recent times, are more efficient than metal fastenings,” argued James E. Gordon in The New Science of Strong Materials, the best study ever written on why some things hold together and why other things fall apart.

When Thor Heyerdahl built the Kon-Tiki for a voyage across the Pacific, its structure was lashed together, not only to prove a historical point, but because this was the only method of fastening that held any hope of keeping the soft Peruvian balsa logs from falling apart. When Fridjtof Nansen and Hjalmar Johansen left their ship, the Fram, frozen in the polar ice at 84°N in March of 1895, to see if they could reach the pole on their own, they took lashed-together sledges and bamboo kayaks, and made it back to Franz Josef Land — 15 months later — alive. Their survival hung by a thread. “When, for instance, a rib had to be re-lashed,” explained Nansen, “we could not rip up the old lashing, but had to unwind it

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carefully in order not to destroy the line.”

When I built a treehouse 95 feet up in a Douglas fir on the coast of British Columbia (see MAKE, Volume 05, page 190), I used #15 tarred nylon seine twine to tie the framework to 14 different branches, not because I had any objections to pounding nails or driving lag bolts into living wood (working around logging camps had cured me of that), but because I wanted to be sure that house and tree remained attached. The entire structure had to be able to flex wildly in 60-knot winds, and no mechanical fasteners were flexible enough.

The puzzle is not why did human beings start lashing things together, but why did they stop?

I adopted lashings when I began constructing aluminum-skeleton kayaks, not for historical authenticity — or I would not have used aluminum — but because tensile fasteners made practical sense. When two pieces of high-tempered, thin-wall aluminum tubing are attached with eight turns of 60-pound test twine, you can be sure that it will take something close to 8× 4× 60, or 1,800 lbs., to pull them apart. There is no risk of metal fatigue, and the joint will flex elastically (and repeatedly) long before it breaks. Shock absorption is built into every joint.

If you sew two pieces of tempered aluminum plate together, there is no loss of temper as in a weld, and none of the corrosion that affects metal fasteners

Photograph by Beverly Dobbs, ca. 1906, courtesy Baidarka Historical Society