In the early 1950s, ripples began to disturb the surface of our ignorance about the world under the sea.

A small sport shop in Los Angeles had received, and sold, the first 10 Aqualungs in the United States. The shop did not renew its order. As the proprietor explained to the inventor: "Obviously, the market has now been saturated."

In New York, the inventor was showing a movie, which he had made with undersea camera equipment of his own design, to a group of potential backers of underwater missions. When the guests had gone, the filmmaker andhis bartender went on a mission of their own: to return the unopened whiskey bottles to the store, in hopes of a refund.

Elsewherei in the country, in those preamphibious days, people were reading a curious new book-Jyrical, scientific-sounding and very adventuresome-called "The Silent World." It sas a sort of book unfamiliar now-an explorer's tale of "menfish" stalking the corridors of sunken ships, and it was as full of unexpected wonder, as if unheralded astronuts had quietly returned with pictures of a buggy ride on the moon.

The inventor, moviemaker and author was the same man, of course, a skinny, unknown Frenchman named Jacques-Yves Cousteau.

He is still skinny, but the Aqualung, which he devised during World War II with engineer Emile Gagnan, is now a universal tool for recreation and investigation. He has been the co-author of a dozen books, made 25 films for theatres, and 52 television programs. Somewhere along the line he became Captain Cousteau, adopting all of us-even those who seefishes only in the market-as his crew.

The Calypso sails again tonight, at 8 o'clock (See COUSTEAU, B9, Col. 1)(COUSTEAU. From B1) on Chanel 26, this time for the Aegean to seek out the remains of the Brittanic, a sistership of the Titanic that went dowin 1916. Was she the victim of a German mine? Hit by a barrage of torpedos? Was she indeed an inocent British hospital ship, or wasit a cargo of munitions in her hold gram is the first of a new series of 12 that sealed her wartime fate? The proCoustear odysseys, four, for public television and funded by AtlanticRichfield-yes, an oil company.

Cousteau will be at the helm, mellifluous in accent as before, meting out the drama of his documentary-entertainment in what has become a classic television style.

At the moment, however, Cousteau is ensconced in a siute at the Madison Hotel. And at the moment, the televisionimage has begun a slow dissolve:

"I'm going to kill that ...."he says, naming a professional associate, eyes flashing behind the steel-rimmed glasses. "We work our-off trying to make a good film, and distribute it, and now this....." The issue is a technical one, having to do with the handling of tonight's program. "It's a scandal." he says, leaning forward in the chair.

Then the laugh. Short-lived and only slightly self-deprecating, it is a laugh one does not recall from TV. The laugh of an early-riser, a hard competitor.

And in fact, the gentle captain frequently sleeps but two hours a night and two hours during the day. That is how he gets things done. "It's true. I'm not enslaved to sleep."

The laugh has hardly faded when he is off on "Jaws." No, he hasn't seen it, wouln't waste the time. "Jaws is utterly stupid. Do you know, one of the men in it is even reading one of my books? So I am told. Ishould have sued them for that. It is all fiction, why isn't it labeled that? I think in a certain way this film is destroying what I have worked for-the reconciliation of man and nature."

The meld-mannered, somewhat neurasthenic, Professor Oceanus figure is now wholly replaced by someone else: a crusty, hyperactive, combat-ready, 67-year-old expedition leader. With 22 broken bones to his credit.

"Let's see, 11 of them at once-a car crash, what else-and then, ah, both feet, left arm, manyribs, five verteger, which I caught in a propeller."

His son Philippe, 37, whom Cousteau taught to dive as an infant and who now rates co-producer billing, is trying to catch up, he says. The son now has three broken bones, having been badly injured in the crash of an autogyro on Easter Island 13 months ago. The incident will be part of an upcoming program.

In the early days of compressed-airdiving the experiments were often done on,as well as by, the experiments were often done on, as well as by, the exCousteau and his comrades, Philippe Tailliez of the French navy and a "fabulous creature"named Frederic Dumas, systematically tested the bounds of their new world by choking, freezing and convulsing at its outer limits.

They studied the effects of nitrogen narcosis, the intoxicating by deadly "rapture of the deep,"by succumbing to it. They pushed theirprototype Aqualungs deeper and deeper, seeking the point of no return, until a companion found it-at396 feet-and died there.

Coustear took the first pictures of torpedoes being fired underwater-head on, at a range of six feet. Dumas tested the effects of explosions on swimmers-by setting off hand grenades beneath himself. They revised the decompression tables by getting the bends.

"We were the three...friends."Cousteau said, seeming to consciously avoid the word musketeers. "Yes, Dumas still lives: he is retired as soon as he got out of school. I do not see him regularly. He is an individualist."

How different these acquanauts, with their madcap, trial-and-error ways, from their space-travelling successors, the Astronauts "And you know why?" Coustear explains, "Nobody cared about us in those days."

Now many people do. He has four TV shows in the works, two more books, and a travel schedule that is zealous even by promotion-tour standards. Hebeleves nuclear waste to be the great threat to the sea, much greater than oil. That may not be much comfort to his new sponsor:

"Why worry about oil when there won't be any left in 35 years?" And he wants be the first person to make an interesting film ("youmust never preach")about pollution.

He is a good bet to do it. Tonight's program has its problems, since the Brittanic lies deep in the unphotogenic darkness, and the issue of her sinking may seem somewhat remote by now. So Cousteau found Shiela Macbeth-Mitchell,an86-year-old survivor of the disaster, and invited her to dive to the wreck with him. She did, and she steals the show.

A close one? He shrugs. Saving endangered documentaries is as much a part the game as saving endangered species of sea life.

There are no miracles. Life is a game, nothing to be concerned about. You have many projects-if they do not work out, who cares?"

The eyes are flashing again, and the laugh returns. "How could that possibly affect your happiness?" Cousteau demands. "Psychiatrists? It's nonsense. The real things are the sun, the sky, the rain in the streets."