Life goes on in Harlem. Even when five gray-and-silver tourist buses with window posters announcing "National Geographic's Evening in Harlem" chug from midtown Manhattan to 125th Street on a quiet Wednesday night.

No one outside the office building on the shadowy neon and iron-grilled strip of 125th Street, one of Harlem's long-standing symbols, gave the buses a second glance as they delivered a spirited and curious contingent of Madison Avenue exccutives: But those hurrying inside for the publication party - the advertising powers, the writers, the photographers, the politicians and the solid Harlem citizens - seemed to think the goings-on held historic consequences.

National Geograhic Magazine, since 1888, printed purveyor of world cultures, was again trying to shake its reputation for rarely reporting the harsher, more complex sides of life, along with its gentle beauties.

In its February issue the magazine presents a 30-page article on the History and lifestyles of Harlem. It is the magazine's first look at a black American community and a sharp departure from its old images as the schoolboy's mecca for dark-skinned erotica.

What ever the Georgraphic's motives, uptown folks basked in the attention the publication's 9.5 million readers almost certainly will provide.

"This is a rediscovery of our people and our resources. It reminds me of the past." announced the Rev. David Licorish, a past associate minister of the late Adam Clayton Powell's famed Abyssinian Baptist Church, roaring with the buoyancy and boisterousness long associated with his name.

Even the younger uptowners, like Judge Davis, a community organizers, who first name is often mistaken for a judicial title, gave the Geographic a warm welcome. "I allow them 51 per cent simply because they are trying." said Davis. As the crowd of 600 turned Vincent's Place, a restaurant housed in the world's largest black-owned office building, into a jovial steam bath, the optimism thickened.

James Van DerZee, renowed 90-year-old photgrapher of Harlem's more glamorous era, edged blues pianist Sammy Price away from the piano and toyed with "Sweet Georgia Brown." Percy Sutton, Manhatten Borough President who has announced his candidacy for mayor and a Harlem resident for 26 years, politicked aggresively. In one corner a crowd gathered to watch slides of the article's photographs, a striking collection that prompted Annette Samuels, whose Community News Service went broke, to say wisfully, "it proves what you can do with money."

Still, some guests expressed cynicism that in 1977 a group of whites would troop a Harlem for a party.This pratice, prevalant before World War II, helped give Harlem its reputation as a high-stepping section of Manhattan, injecting income into its entertainment businesses, but simulaneously glossed over the growing unmanageablility of its social ills. And though in many ways Wednesday night's affair prompted images of those bygme social safaris, everyone was too polite to categorize the Geographic's generosity in that manner.

"Harlem has almost died from its bad publicity," said Joe Kirkpatrick, owner of the landmark restaurant Jock's. "This will help revive the faith. It's just a matter of time before Harlem's day comes around again.

Another factor adding interest in the gathering was simply that the party's sponsor was the Geographic, the Washington, D.C.-based, oak-leaf-and-yellow-bordered magazine. Traditionally, several editors there said, it has treated black life as primitive and exotic. Since 1949, when the magazine published a regional article on the South that totally ignored blacks in the text and photographs, the changes have been slow and somewhat self-conscious.

In 1970 a newspaper writer looked at the magazine over the decades and concluded, "No Geographic article on any state in the Deep South in the past 50 years, for example, has mentioned segregation, malnutrition, the Ku Klux Klan, lynchings, sit-ins or freedom rides." Such old rosy interpretations have also touched upon other areas of the world; a 1937 piece on Berlin, for instance, never once mentioned anti-Semitism or Adolph Hitler's secret police, the Gestapo. Since 1970, when Gilbert Melville Grosvenor became editor - the fifth generation of the family to be associated with the Geographic - "the old theories of avoid the negative have been thrown out," he says.

At the party , Grosvenor, who would have been inconspicuous in the striped-suit crowd except for the ring of photographers around him, was quickly catching up with some of the cultural personalities long ignored by his product. Geraldine Griffin, owner of Adele's Kitchen, a popular Harlem restaurant, boasted about the collection of Geographics in her attic, and Anna Arnold Hedgeman, an educator and civil rights activist, told Grosvenor his magazine has been "a fine educational tool, despite its inconsistencies."

Explained Grosvenor, "We haven't received any outward criticism of the magazine's coverage of blacks, but no, I don't think we have been honestly responsive to black culture in America. I wouldn't call this a change of consciousness. We feel we have always managed to evolve with contemporary interests."

Partly because "all New York was just too big," according to Grosvenor, but also because Harlem provided its own cohesiveness, that neighborhood was chosen for the spotlight. And, as a result, sandwitched between an article on naturalist and bird painter John James Audubon and balloonist Ed Yost, a lyrical view of Harlem unfolds.

Photographed by LeRoy Woodson Jr., a Washington photographer who lived in Harlem for six months, the article was written by Frank Hercules, a Trinidadian-born writer who this month moved from Harlem after 25 years.

"It became difficult to go out at nights without molestations. My wife and I have both been held up in the last couple of years," said Hercules. "But no matter where I wonder my heart will always be in Harlem."

In his article Hercules uses the same intimate and fond tone, blending his emotional romanticism about the community's 564,000 inhabitants with cold facts about Harlem's catastrophic social conditions.

Though in recent years the Geographic has written about the unglamorous and sometimes horrifying plight of Americans such as migrant wheat harvesters and the displaced Cuban community in Miami, and ran an article on APpalachian residents in which black lung disease was bluntly discussed, the magazine has refrained from assuming an advocacy role.

"Basically we will continue to be fair and objectives," says Grosvenor. "If we err on the right side of life."

That nonpolitical and conservative approach should continue to please the advertisers. Last year the Geogaphic earned a gross advertising revenue of nearly $20,000,000, the only portion of its estimated $100,000 total 1976 grosses that were taxed. The Geographic Society is the world's largest scientific and educational institution and as such has a special tax status. Grosvenor says the profits are reinvested in research.

When the miniature chicken legs and meatballs disappeared (No, we are not having sould food," explained the press representative." That would be too patronizing.") the Madison Avenue crowd hustled back to the buses.

The echoes of the departing chatter seemed to indicate that the Geographic had made its point. Elliott Skinner, former ambassador and distinguished anthropologist, said, "I've regarded Geograhic as a journal that a missionary reads and can be found in a doctor's office. Good data, yes, but not very fair to blacks. But I think it has done the Harlem community a service by focussing on it."

It had also been a hit with the downtowners. "As a New Yorker, the article gave me great new insight into Harlem, said Anthony C. Chewins, president of Cunningham and Walsh Advertising. "For people who work in New York and think of Harlem only as a place to be devoutly avoide, except on the way to Connecticut, it makes it more human.