Walter Leland Cronkite sat in an office, quietly talking about pols and presidents he has dealt with over the years.Suddenly, he sat straight up in his chair and looked to the window.

I watched, puzzled, as Cronkite rushed to the sill, leaned out and stared anxiously into the street. Moments passed before I realized: he had heard a distant fire engine. He stayed at the window as the engine moved through the traffic, passed the building and disappeared down another street. Only then did he leave the window and politely ask, "Where were we?"

At the time, Cronkite was more than 60 years old, having been a newsman for more than 40 years and CBS anchorman for more than 15 years. But still, the naivete and enthusiasm he has had since covering his first stories in the late 1930s were running on virtually undiminished.

Now daily news for Walter Cronkite finally is over.

He has sat in the CBS anchor chair for 19 years. In that time, six presidents have come and five gone. One of them was murdered, one resigned in scandal, one quit in dismay after a single term and two have been voted out of office after a single term. During that time as well, four national leaders have been shot in political acts. Three died. Five years of protests swept the nation, and three years of riots burned in our cities. And more.

Cronkite has reported it all. People may not watch television news constantly, nor read newspapers and magazines every day, but television news is our only truly national journalism. It covers the great events live, as no society has ever seen them, and gives us daily bulletins in between. And Cronkite is the longest-standing, best-known figure of that national journalism.

Though it is brief, network television news has risen above the level of most local journalism in the United States. One reason for the quality of journalism on television is Walter Cronkite and the tight ship he has run at CBS News.

Intruding on what Cronkite has accomplished, and television journalism has achieved, are the illusions engendered by the show-business aspects of television. Because anchormen use makeup, because Cronkite keeps a miniature pharmacy nearby to care for his voice (he once had surgery to remove a throat polyp and at conventions has had a nurse standing by to soothe his throat), because the news is an island awash in a big-dollar entertainment medium, the quality of its journalism and its show business are often confused.

Virtually every story about Walter Cronkite written in the past decade has listed in detail reports of how he is perceived. People are convinced Cronkite it 6-foot-2 (he is shorter than 6 feet); homosexuals have said they think he is gay; a cab drive once asked him how he had enjoyed a recent Jewish holiday, and when Cronkite said, "What holiday?" the hacker decided Cronkite was passing as a gentile, which he is.

There is even a certain intimacy about the illusions connected with Walter Cronkite. Autograpoh seekers call David Brinkley, "Mr. Brinkley," but address Cronkite only as "Walter."

The intimacy that comes from having a voice and face in the living room daily is enough like relations with a real person to make some viewers uncomfortable doing private things while Cronkite is on the tube. One woman marched down to CBS, somehow found her way to the newsroom and told Cronkite she was dreadfully sorry: she promised never again to do the terrible things she had been doing in front of the television while he was on.

Cronkite is better known than John Wayne or Clark Gable, and polls have shown year after year that he is more trusted than nearly all national political leaders. In the Nixon years, his trust rating was 17 points better than the president's. When the Ladies' Home Journal polled its readers on which newsmen they most trusted, Cronkite won with 40 percent. "None" was second with 31 percent and Dan Rather rated 4 percent.

But all of this is as ephemeral as gossip. More important than being the star of TV journalism, Cronkite has been an important figure in shaping TV news, in retrieving it from what it might have been -- 30 years of Movietone newsreels.

In most ways, Cronkite has been a tough and skeptical editor. Tom Phillips, once editor of the Cbs eVening News, said that among the first things Cronkite would do when he sat down in the anchorman's chair, about two hours before air time, was ask for a briefing. Cronkite was tough in his questioning and could get abusive and angry at times. The situation, Phillips said, was like a recruit facing a drill sergeant: "There was noise and chaos around me; I had to speak in a loud, clear voice, and in about 10 words for each one, explain why each item is not in the lineup," Phillips said. It was as if the recruit saluted and repeated loudly and rythmically to the sergeant: "Sir! These are the decisions I made today and why I made them, Sir!"

Even late in the day, Cronkite regularly pushed writers to make more calls, get more information, fill out details of stories. One former writer recalled his sinking feeling when a diplomatic story broke after 6 p.m. "Get the State Department reaction," Cronkite ordered. The writer made the mistake of lamely pointing out that the State Department closes at 4:30 p.m. "Goddam it! Do I have to do everythink around here?" Cronkite retorted. "You had better get something!"

As it turns out, at least three of the show's former writers -- and some say more than that -- became heavy drinkers. One executive producer said it might be more than the job alone that has caused trouble for some writers who have worked the Cronkite show: "Is it the job? Or is it pressure from Cronkite? Well, maybe the answer is that there are three writers doing at most only eight minutes of copy. All day. That's about two dozen pages, triple-spaced, in big type. But Cronkite bounces the copy back to them a lot, and often very late in the day."

And when the broadcast was finished, Cronkite was not. Daily he headed into the producer's office to watch the NBC Nightly News. Some of the loudest of Cronkite's explosions have occurred in those minutes, when he saw a story or even a single fact that CBS did not have.

One former CBS executive producer confessed, "I am not normally a fearful man, but I ended up dreading that half-hour when Walter watched the NBC News . . . Whenever he thought they did something better, he was likely to blow. Fortunately, Walter's anger is like a summer thunderstorm: it blows over quickly."

Friends say it about him, and he says it about himself: "I want to win. I not only want to win, I want to be the best. I feel very badly if I can't be."

That means at everything. When Cronkite first took up sailing, he owned a small boat called a Sunfish. Races in these boats for weekend sailors are not always taken seriously. "But if Walter didn't win those Sunfish races," said a friend, "he would come home with a stomachache."

Dan Rather, who is now in the anchorman's chair, is in many ways utterly unlike Walter Cronkite. The two have never been good friends, perhaps because their personalities are so different -- Cronkite's warm versus Rather's cool, Cronkite's openness versus Rather's reserve. Cronkite is a storyteller, a man who will sing and dance and do bad imitations at parties. He once said that if there was anything he ever wanted to be beside a reporter, it was a vaudeville performer: "One of the great things in life would be to entertain people with songs and dances and funny sayings."

But Rather is far more serious. He is deliberate and courteous to the point that he refuses to pick up a ringing telephone while he is talking to someone in his office. He is frank about his own ambitions and failings. When he learned about becoming Cronkite's heir, he said it made him think of many others at CBS who could do the job just as well; it made him reflect on the number of times he hadn't done his job as well as he might have.

Rather defines his journalism more personally than Cronkite. Searching for what makes the final best expression of his career, he did not say as Cronkite does that he simply wants to be a good workmanlike journalist. Rather said, "When I am gone, the best someone could say about me to my children would be: 'He did not buckle. Not before President Johnson, not before President Nixon.He stood his ground . . ."

When Cronkite joined CBS, TV news was no place for journalists. It was for actors, professional voices who read the news the way they read Timex commericals. The anchorman seemed to be a necessity of the stagecraft; with so many disparate bits of film and talking news, someone had to act as ringmaster.

When Cronkite first acted as a news anchorman on Channel 9 here in the early 1950s, he took over the job with instructions to turn it into a solid news program. In that first anchor job, working the late-night news on what is now WDVM, Cronkite even brought a blackboard onto the set to make his point. On it he drew diagrams and gave "chalk-talks" in the military style to make clear the events of the war in Korea.

When he eventually took over the CBS Evening News in April of 1962, he gave himself the title of managing editor to dispel the notion that he was a reader and that his news was a "show."

The same year that Cronkite became CBS anchorman, Dan Rather was a green reporter at the local CBS station in Houston who had been scouted and passed over for promotion to the network. But during Hurricane Carla in 1961, his station sent him to Galveston Island to cover the storm, where he became marooned for three days.

He did not stop broadcasting as the storm grew worse, and the network began broadcasting Rather's local coverage to the rest of the nation.

"We were impressed by his calm and physical courage during that hurricane," Cronkite said, "He was ass-deep in water maccasins." The year following the hurricane, Rather was hired by CBS and sent to cover the South, where George Wallace would soon stand in the schoolhouse door and John Kennedy would be shot.

For Cronkite, even after 30 years away from wire service reporting, colleagues instinctively think of him as essentially a wire man. "Walter has a feeling that every angle has to be covered -- every angle," said Roger Mudd, now an NBC correspondent. "He still has a lot of wire service in him. Walter has a very logical mind. You can almost hear it humming like a wire servie ticker, going dik-dik-dik-dik. In my earphone I can hear Cronkite up in the booth saying how many gallons of orange juice the delegates have drunk, dik-dik-dik-dik . . . "

Because Cronkite does not write his own copy (though he edits it ferociously), two writers and an editor put together the seven or eight minutes' worth of "Cronkite tell" stories that get on the news.

One of his writesr described the Cronkite manner of handling news: "Walter has an almost messianic turn of mind. He feels so much reponsibility; he feels that if he doesn't get it right, nobody is going to get it right. He feels everybody else is too lazy. He's right.

"Most other people will not take on the weight of the world. Because nobody else is doing it, he's got to do it all. And it p---s him off! That's kind of enderaring," the writer said. "That is Walter's main characteristic -- his obsessive idea of personal reponsibility for the world. That's what I would call messianic. And that is the reason he is number one. It comes across. People know that Walter Cronkite would never lie to them. Never. Because it is his religion. He is in charge of dispensing truth to the public. And he really believes that. In a way it's comical, in a way it's silly. But that's his genius."

Walter Cronkite has been the competitive engine of CBS news, and what shaped his attitude toward the gathering of facts, toward the necessity of completeness and accuracy, was a series of youthful blunders.

Cronkite's father and grandfather were dentists, but Walter, from age 6, wanted to be a newsman. By the time Cronkite was in college at the University of Texas and found himself flunking all his courses, he had become so interested in news and his part-time job at The Houston Press he dropped out of college altogether. He was taken on at the Press, given $15 a week and run through the usual young reporters jobs -- police stories, obits, court cases and what was called "picture chasing."

Picture-chasing was an art especially intended to turn young hearts to stone. When a man achieves some local distinction, such as getting himself murdered, the local newspaper sends the youngest reporter to the home of the very recent widow to beg the weeping woman for a picture of her late husband.

Sent to fetch a picture of a man who had just been killed, Cronkite sped to the victimhs home, pounded on the door and waited. And waited. No one was there. But Cronkite had his orders, and through the window he could see a photograph on the mantel.

Cronkite knew his duty. He broke into the house, stole the picture and raced proudly back to the office.

Cooler heads soon discovered Cronkite's mistake. He had burgled the wrong house and stolen a picture of the dead man's neighbor. Cronkite's embarrassment was bad enough, but he also had the problem of how to get the picture back without confessing burglary. In the end, the picture was put discreetly in a plain brown envelope and sent back anonyously.

After two years at The Houston Press, he took a job at KCMO radio station in Kansas City, where he faked radio broadcasts. Western Union sent reports of college games to many radio stations, giving the action after each play.

Cronkite ripped these reports off the wire and embellished them. He pretended to be at the game, in the press box watching the plays. "Now they're back in the huddle," he would say in low tones, "and they're coming out in a T . . . " The deception became elaborate. He got recordings of band songs and crowd noises, he got the names of season ticket holders, phoned wives to find out how they were dressed for the game and got charts of the card stunts the colleges would do. Peppering his monologue with such details, he earned a reputation not only in Kansas City, but elsewhere.

Cronkite was later hired by a big Midwestern radio station, WKY in Oklahoma City. "They wanted me to do the broadcast of the University of Oklahoma football games.I wouldn't have done it, but they offered me four times my salary at U.P.!" Cronkite said.

Cronkite and the Oklahoma games were sold to a cereal company as a first class sports package. But Cronkite had never broadcast a big football game. He had only faked it. To protect himself from errors, as well as from having to do a lot of hard work, Cronkite devised an elaborate plan. He hired several spotters and had the radio station build him an expensive electronic system to link him with the spotters. They would be in the stands and would punch buttons on a board for the formation, for the numbers of the ball carrier, for the tackler.

It was beautiful: Cronkite could sit up in the press box and hardly even look at the field. He could sit and watch his electronic board flashing, and speak on from there.

The day of the first big game, officials of the radio station invited a group of cereal executives to the game. They sat together, near the press box. But the moment the game started disaster was aparent.

The spotters hadn't done their homework. They were slow in punching buttons. When they did, they were the wrong buttons. With the play moving down the field, Cronkite sat staring at an electronic board gone mad. In desperation he tried winging it -- actually calling the game by watching the play on the field. But he had trapped himself: He hadn't done his homework either. He didn't know the players' names or positions and couldn't follow the action.

Worse still, after every play Cronkite could hear the moans from the cereal and radio executives: "'OOOh My God! Jeeeesus Christ!'

"It was really one of the lowest moments of my life," Cronkite said. "When it was over I just wanted to go out and silently slip away. But I stayed in the press box, waiting. I remember finally when there was no one there, walking slowly out . . ."

The next work moring he crept into the station and found a message that the boss wanted to see him. To his surprise, Cronkite found the boss willing to keep him on if he cleaned up his performance.

For the 23-year-old Cronkite, it was a lesson he would not forget: Do your own work; dig hard; prepare mightily. Through the rest of the season he memorized the names and numbers of every player, on both teams, the formations and the plays. He was back doing the real research he had done for those faked broadcasts that first brought him success.

The habits of research and accuracy were now burned into his mind. Years later. when Cronkite began broadcasting political conventions and spaceflights, he started weeks before the events.He searched exhaustively for details, for anecdotes, for background material. He put all of it together in huge books divided into categories. He took these on the air for reference as he spoke. But he rarely referred to them. He had committed masses of the material to memory. This is still his habitual way of covering events and has been a model for network journalism.

Rather's experience is not so heavy in print and wire service reporting as Cronkite's, but instead Rather has worked more in radio and local TV, the modern way of becoming a network reporter. The result, according to one CBS producer, is a greater command of the medium, more authority on the air, but a somewhat less-developed reportorial skill.

His continuing toughness in standing up to President Nixon won him respect at the network and eventually earned him the anchorman's chair. And the difference between Cronkite and Rather as CBS anchormen are likely to be the difference in their brashness. Rather, who recently painted his face, put on rags and sneaked into Afghanistan to cover that war, will now try to be a reporter-anchorman in a way his predecessors have not, trying to carry off more feats like his Afghan adventure.

A few years ago, Walter Cronkite sat in his office talking about his career and retirement. He reflected on some of the happiest years of his life -- the war when he was a United Press wire service correspondent -- and he bacome so enthusiastic about those memories that he said something seemingly unlikely.

"I . . . I've always . . ." He stopped and began to laugh at how funny the idea might seem. "It's very hard for anyone to accept," he said smiling. "And I don't really expect you to accept it, or anybody else to accept it. But I know in my heart it's true . . ." He said he could climb down from the money, fame and influence of his extraordinary job and go back to being a hack reporter.

"I would miss a lot of the financial emoluments. I would probably miss the fame, although the fame has probably spread to the point that I would still get a table in a restaurant . . . and probably could still get people on the telephone.

"But it's always been my feeling that if it didn't work out anytime here . . . and UP had taken me back . . . I would have been just as happy. Maybe even happier.

"I just want to do a news job. I want to be in on the big story," he said finally. "I want to be there when it happens. The role I play is not critical. I don't have to be in front of a camera . . ."

Now, leaving the anchor chair at CBS, Cronkite has in part got his wish. He has gone back to reporting -- he will be taking a trip around the world, doing stories from many countries, then when he returns he will do his weekly "Universe" science news program. There will be some news specials.

His only parting comment: "I wish I could have put it off a year. This is going to be a fascinating news year, absolutely fascinating. Reagan has got an opportunity that few men have had in recent history, not since Franklin Roosevelt, really. . . ." Dik-dik-dik-dik. You can hear the wire service ticker running.