Marcia McCroeklin, age 9, of Madison, Tenn., for her question:
How do they run telephone wires over the oceans?
Everybody knows that those high wires strung along from pole to pole carry our telephone conversations. You can even call overseas and talk with a friend in France across the ocean. Fixing the lines to carry such telephone conversations overseas is a very big job.
In most places telephone wires and poles tend to spoil the beauty of the landscape but we get used to them and they become part of the scenery. They are very useful, for they carry most of our local calls to friends across town and many long distance calls to friends in other states. We can call up people in l70 other countries, and most of these places are across the ocean.
Long cables laid on the floor of the ocean carry conversations overseas. When you call up a friend in France, your voice travels 2,000 miles along a cable that stretches across the floor of the Atlantic Ocean. Your friend's voice travels back to you along another line in the cable. If you call a friend in Honolulu, your conversation is carried along 2,400 miles of cable on the floor of the Pacific Ocean.
The first telephone cable across the Atlantic was laid in l956 by the British ship Monarch and her crew of experts. The heavy copper cable was taken aboard and carefully coiled in sections. As the cable ship went ahead, the heavy cable was strung behind and allowed to sink to the ocean floor.
The seabed is always shallow near the shores, but it soon dips down two or three miles to the ocean abyss. There are many ups and downs in the deep ocean bed and the cable dips down the hollows and climbs up the humps. Deep water cable is l2 inches thick, and a mile of it weighs 24 tons.
An Overseas telephone conversation is sent through the wires by electric power. There are big electric generators on shore at each end of the cable. The sound weakens as it travels, but the cable has built in gadgets to magnify it. every 30 or 40 Miles there is a repeater that boosts the falling sounds a million times. On its way to France, your voice is boosted by 5l underwater repeaters in the cable. The words that reach your friend's ears are as loud as the Voice you used to speak into your phone at home.
There are now about 50 special cable laying ships in the world. each can carry more than 3,000 Miles of cable and lay about 200 miles a day. The many copper lines in the cable are padded and jacketed with water proof metals. The expensive repeaters have extra protection, and cable ships are ready in Case of trouble. Any part of the line can be inspected or mended but it must be hauled up to the ship, sometimes from more than three miles below the waves.