Into the Sea Age?

THE SILENT WORLD (266 pp.) -- Captain J. Y. Cousteau -- Harper ($4).

When the French Poet Gerard de Nerval was asked why he walked a lobster on a leash down a Paris boulevard one day in the 1840s, he replied: "He knows the secrets of the sea." Until very modern times, most of the sea's secrets have been known only to the sea's inhabitants, and they never tell. In the last two decades, however, a new species has joined the finny tribe: the men-fish, who, with flippers on their feet and an air tank on their backs, go down into the waters and come back to tell what they have seen.

In The Silent World, a French navy captain named Jacques-Yves Cousteau, inventor of the "aqualung," describes his underwater adventures with a scientist's care and a poet's feeling.

Rapture of the Depths. Cousteau perfected his seagoing lung in 1945. The key to its operation is an automatic compensating valve that adjusts the air supply to the diver's demand and the water pressure. The outfit weighs about 45 lbs. above water; submerged, the man and the machine when properly ballasted weigh hardly a pound.

A diver, merely by filling or emptying his lungs, can change his waterborne weight by as much as 12 lbs. Let a diver deflate his lungs and he sinks like a stone; inflate them, he pops up like a cork; intermediate effects are easily learned. But descent below 300 ft. becomes increasingly dangerous. One reason for this is something Author Cousteau calls, from experience, the "rapture of the great depths."

The rapture, which comes on at about 200 ft., is apparently caused by the oversaturation of the nervous system with nitrogen or carbon dioxide under the increased pressure. "The first stage," writes Cousteau, "is a mild anesthesia, after Which the diver becomes a god. If a passing fish seems to require air, the crazed diver may tear out his air pipe or mouth grip [and offer it to the fish] as a sublime gift."

Cousteau describes one attack in detail: "My mind was jammed with conceited thoughts and antic joy. I struggled to fix my brain on reality, to attempt to name the color of the sea about me ... navy blue, aquamarine and Prussian blue. The debate would not resolve. The sole fact I could grasp was that there was no roof and no floor in the blue room . . .

"Childhood nightmares overruled my mind. I was ill in bed, terrorized with the realization that everything in the world was thick. My fingers were sausages. My tongue was a tennis ball. My lips swelled grotesquely on the mouth grip. The air was syrup. The water jelled around me as though I were smothered in aspic. I hung witless on the rope. Standing aside was a smiling, jaunty man, my second self, perfectly self-contained, grinning sardonically at the wretched diver. [He] ordered that I unloose the rope and go on down . . .

"I went to the last [depth-marker], 297 feet down ... In my bisected brain the satisfaction was balanced by satirical self-contempt. . . [Back] at 264 feet, the rapture vanished suddenly, inexplicably and entirely."

Where Blood Is Green. The underwater world is a silent world, Cousteau testifies. "Hydrophones have recorded clamors that have been sold as phonographic curiosa, but . . . it is not the reality of the sea . . ." As for most of the conventional perils of the deep, the men-fish call them just fish stories. Cousteau says that he has never been attacked by an octopus--in fact, he has actually waltzed with them dozens of times on the sea floor, and he has movies to prove it. Only once was Cousteau in danger from a shark; and that was when the blood-spoor of a dying whale was near, and the sharks were half-crazy with hunger and excitement. Cousteau scared the beast away by banging him on the nose with his underwater camera. A far greater nuisance, he says, is fire coral, which on contact produces a severe burning rash.

Among the richest and strangest of the sea changes are those that afflict the colors. At 15 ft., red turns pink; at 40 ft., it becomes black. Orange disappears at the same depth. Yellow lasts until about 120 ft., where it begins to turn green. Below 25 ft. color loses about half its value. Once, at 150 ft., Cousteau cut his hand. The blood spurted out--green. At 55 ft. the blood turned dark brown, and back at the surface it was red. Cousteau has included more than 100 excellent underwater photos in the book, about 20 of them in color.

Cousteau's basic message: an appeal for an organized attempt by modern science and industry to conquer the sea as they have conquered the land and the air. He calls for better diving equipment, the ultimate systematic farming and mining of the sea to increase the world supply of food and raw materials. Assures Cousteau: "The sea age is soon to come."

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