Submarine Plow

The first international underwater telegraph cable was laid in 1850 across 25 miles of English Channel from Dover to Cape Gris Nez, France. The first transatlantic cable was opened by Queen Victoria and President Buchanan in 1858. Since then, in all parts of the world, some 3,500 cables, totaling 300,000 miles in length, have been put in operation. They lie flat and tensionless on the floor of the ocean, avoid undersea peaks and canyons, go no deeper than about three miles, cost around $2,000 a mile. Inside each cable a copper conducting wire, 1 in. thick, is protected by layers of guttapercha, brass tape, jute yarn, galvanized iron.

The thickness of cable covering depends on location. Near shore, insulation is heaviest, up to 4 1/2 in. thick; in midocean, a cable is just over one inch in diameter. Though no cables have worn out their hazards are many--earthquakes, marine worms, icebergs, anchors, wars, fishermen. Finding damaged cables, picking them up is a comparatively simple matter for modern instruments. To keep cables in repair, 30 maintenance ships, strategically placed around the seven seas, go on trouble location at a cost of $1,000 a day, help bring the average yearly cost of upkeep to $300 per mile of cable.

Most troublesome single spot on Western Union's ten lines to Europe is on the Atlantic shelf, 500 feet to 2,000 feet down, off the west coast of Eire. There, halibut-fishers drag heavy iron-weighted nets over the ocean's floor, frequently break cables, sometimes hoist them to the surface, cut them with an ax. To stop this Irish interference, the 2,641-ton, Canadian-manned cable ship. Lord Kelvin, put out last week from Manhattan. Aboard was three-quarters of a mile of nickel steel chain, longest ever forged, to drag a submarine plow Western Union has been developing for the past three years. The steel "plow" weighs ten tons, is ten feet long, four feet wide, three feet high, resembles a gigantic stone boat. Beneath its rear end a keel furrows 16 inches deep in the ocean floor, feeds a cable over a wheel into the trench. The churning wheel and sea's action quickly refill the furrow. Submarine plows can bury 15 miles of cable a day, may be able to save cable companies $500,000 a year.

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