They say a ghost walks National Theatre.

He dresses like Hamlet, appears at the prompter's table on opening nights and, says one who saw him, is " very peaceful." But, like most ghosts, he doesn't stay around long enough to identify himself.

What more likely place a ghost than a theater that, through it burned to the ground four times; has been same site 142 years? It knew Lincoln in its audience and Jenny Lind on its stage. On a night that changed history, C.D. Hess, then manager of the National, wired the owner in New York: "Lincoln shot at Ford's Threatre. Thank God it wasn't ours."

Actually, somebody was shot in the National Theatre once, and about a hundred years later I went to learn what I could about it. Richard Schneider, who's the manager there now, sat on a chair arm in the orchestra section one afternoon and gave an oral history of the theatre. He used a notebook to remind him of facts: how, in 1881, a drunk fell out of the balcony and into the orchestra, surprising only himself - he was sleeping it off all night in a locked theatre - and breaking a few chairs.

Of course, that was before the murder in the basement, and before the ghost.

In those days, the old Tiber Greek ran through the basement. (In recentthe old Tiber Creek ran through the basement. (In recentDistrict's sewage system.) Always, Schneider said, the acoustics on the stage have been perfect, and some think the creek and a cavernous opening under the stage floor make it that way.

The creek and the cavernous opening are related in another way. One day, in the late 1800s, a bit-part actor was washing his clothes in the creek. Another actor came looking for him in the basement, shot him and buried him in some dirt under the stage. They'd been feuding on their tour, over a woman.There were no witnesses, and the murderer confessed.

According to a former manager of the National, Scott Kirkpatrick, the police called the murder solved, and since no one came asking about the poor bit-part actor, the theatre became his final resting place.

Schneider led me down from the stage to the basement, where water still trickles and gurgles - not through a creek any more, but through pipes.

In the high-ceilinged basement a stage carpenter was sawing two-by-fours and nailing them together. Among the props, we passed a xylophone and, against the wall, a number of black cases, bulbous liknesses of the instruments inside them.

And there, in the corner of the room, behind some plywood, I saw it. I stood on a rolled-up rug and peered past the remaining foundation of a former, pre-fire incarnation of the theater, to the present foundation, built in 1885. In between, I saw a dank, unexcavated area, eight feet wide and 25 feet long. Somewhere in that dirt rests the actor.

Now before the days of Schneider, and before Kirkpatrick became manager 20 years ago, Edmund Plohn ran the place. And it bothered that the body was there. "So," Kirkpatrick says, "he sent me over to the District Building where you get the burial permits. He was going to have him buried where they bury people who don't have any family. At the District Building they were so surprised - "What? Somebody buried in the National Theater?" I ran into a lot of red tape.

"At the same time, the actors heard about it. They didn't want him taken away. They felt an actor would be happier there. We would've gone through with it if the actors hadn't protested. They didn't want him buried in a strange place."

There wasn't much else to see in the basement then, so Schneider led me up the backstairs to stage right. We walked across the stage, past where Dolly sits while the men sing Hello to her. At stage left, and electrician fiddling with the lights turned around, slightly startled, and said, "You hear footsteps - " chuckle - "could be anybody."

Which brought me to a few unanswered questions. Who is buried in the basement, anyway? Schneider said the man's name is John McCullough, and he died around 1885.The body hasn't been turned up yet, not that anyone wants to turn up. But a couple of years ago when stagehand was digging around down in the carven, he found the remains of a very old gun. Schneider took it to the Smithsonian for dating, and they told him it was a Springfield miltary musket predominantly used in the Civil War. Corpus delecti , almost. But it's really too old to tell if it's ever been fired. The hammer and flintlock are corroded and sealed with rust; the wooden parts must've gone to the worms 75 years ago.

It was also about two years ago when "the ghost" was last seen. Schneider said his previous doorman saw it. "But he didn't tell me about it right away. I was unhappy about that." Like Kirkpatrick before him, Schneider has put the word out: "I have instructed the whole staff to buzz me on the intercom if they see him.

"Various watchmen report they have seen somebody - dressed like Hamlet. You spend a few long nights here slaving over payroll, and you begin to wonder, too."

They haven't seen him lately. "But there's a big cast in "Hello Dolly!," and he might have gotten lost in the crowd," said Schnieder.

He was kidding, but the falbed Phantom of the Opera was very big on wearing his death's head in theater crowds.

Well, that was it for the theater, but not for me. I had a name, now, John McCullough, and a year, 1885. I was determined to find out just what happened, and took a cab to the Library of Congress to read it on microfilm.

I think it's called the scattergun approach.

The microfilm for the old Washington Post doesn't start neatly at Jan. 1, 1885. It starts in 1884 somewhere, and in the reading room, I would have to spin the film through the viewer 'til my year came up. I put the film in, klutzed around getting the spool on the spindle, and turned the viewer on. Light showed through in unfocused smudges. I adjusted the focus to clear up the smallest lines in an illustration on the page. The date was Oct. 3, 1884. The illustration turned out to be an old etching of a man's face, and above it, shortened so it would fit the space, was a name: "JOHN M'CULLOUGH."

"It is probable," said the story, "that Mr. John McCullough, whose striking and familiar features are expressively reproduced in the above engraving, will repair at an early day to his home in Philadelphia for the rest he so greatly needs, and the care that he is certain to have from his wife and children at home.

"It has been stated that his domestic relations have not been of a pleasant character, but the Philadelphia Press says quite to the contrary, and intimates that Mrs. McCullough is an amiable and well-bred lady, whose only difference with her husband was his early inclination to the stage."

The front-page story continued, illuminating his illustrious career and describing the paronia that was debilitating him.The message - if there was one, and I think there was - was clear: John McCullough, was no bit-part actor.

"He has long imagined," his most intimate friend told the newspaper, "that the public was tired of his acting . . . His nights have often been spent in walking the floors of hotel bedrooms in vain endeavors to woo sleep. Quite as unaccountable as the impression that his acting was not appreciated is his firm belief that no one likes him, although no man in the profession has wider circles of friends."

I turned to The New York Times index, thinking I would learn, under McCullough's name, the exact date of the murder in the National. Instead, among the 1885 entries for him were these: Jan. 3, accident escaped; Apr. 22, falls in street; June 28, removal to Bloomingdale asylum; Nov. 9, death; Nov. 12, funeral (private).

So, McCullough may have been accident-prone in his declining days, but the accidents were not in the National Theater, and further research uncovered that the funeral (private) was in Philadelphia.

But the National was his favourite theater, and even though he wasn't buried there he turned 11 years later, in 1896, according to an actor named Fred Bond, and a front-page newspaper story.

"McCullough made his last appearance in Washington in 1884. At this time, his mental impairment had begun and his Virginius was a pitiable exhibition of his failing powers. He would repeat himself over and over again and became very moody and preoccupied. Perhaps it is the knowledge that his last performances here were so imperfect that makes his spirit so uneasy. He acts the parts over again, untiring in his exertions to do himself justice.

"His apparition has been observed and recognized over and over again by his personal friends in the theatrical profession. It was seen so recently as one day week before last, by Frederic Bond, the well -known comedy actor. He was sitting, after the performance, at the prompter's table . . . when suddenly he heard a slight noise, and looked up . . . After he had sat there awhile longer he felt convinced that he was not alone on the stage . . . he saw a man walk across the stage, and Bond jumped to his feet and cried "John McCullough!"" Then it vanished in the wings. "McCullough's spook had hardly gone when that of his admirer, who followed him in death as in life, entered. It came from the same spot and walked in McCullough's footsteps, finally melting away in a similar manner. The comedian recognized it as Eddie Specht in the instant it had remained."

Eddie Specht was an ambitious property boy who had recently died, by means undisclosed in the story.

A former stage doorman at the National said he never heard of John McCullough. But, he said, during his 15 years there, he saw the ghost several times. "I just saw a figure of a man. An outline of a man. He walks on the stage looking over a set, usually when a new show opens up."

Was he scared to see him? "No, he was very peaceful. He was just kind of floating."

He said others have seen it, too, "a janitor and a nightwatchman. It's been years ago, and they're long gone, dead."

Is the ghost the person who's buried in the basement? "Well, that's how the old story goes," he said.

"I don't want to be connected with any story," he said. "Last time they used my name, they made me look like a fool.

"When I told anybody about it, they thought I was crazy. The actors are very superstitious and believe in such stuff. They believed it."

Does he believe in things supernatural? "Sure. You would never be able to see them unless you believe in them."

Sure. But whoooo?