Christmas is a time of family reunions and thoughts of peace and goodwill. This is the first of two articles about a search for family roots and a happy discovery in Northern Ireland, where the violence and hate of recent years appear to be muted and tourism is increasing.

"I don't know," said the silver-thatched country gentlemean brusquely, opening his door to a cluster of strangers bearing cameras and notepads. "I don't have any," he continued, casting an austere gaze at the uninvited visitors. With barely a pause, he continued, "I don't want any."

Then he grinned, inviting an explanation.

Kathleen Neill, executive secretary of the Ulster Genealogical and Historical Guild, made the introductions. She explained that my wife and I had come to County Down in hope of tracing Ruth's Scotch-Irish ancestral roots.

We have tropped through the local churchyard, searching among the gravestones for the surname Gibson. We had found several, including one marble marker inscribed with a virtual catalog of the first names of the cast of characters mentioned in Ruth's family archives dating back to the early 1700s.

In particular, we sought clues to descendants of one William Gibson, a 19th-century justice of the peace in Ballygowan. He was listed in the family chronicles as a direct descendant of one of the original Gibson settlers from Ayreshire in Scotland, some of whose progeny reemigrated from Ireland to Canada and the newly independent United States of America.

"I'm Joe Gibson," said the occupant of the house on the outskirts of Ballygowan. "I was the J. P. here, as was my father before me.. Come along inside."

The collision of cultures in the unexpected meeting of past and present is extraordinary to observe. There is initial shock and some consternation on both sides. And finally, the tingling excitement and rewards of revelation.

"It's strange that you should come now," said Joe Gibson. "Not long ago a man came around asking about Gibsons in these parts. He talked to my housekeeper."

Score one for the tireless toil of the Ulster genalogists, who used the sketchy information provided in advance of our visit to blaze a trail to the doorstep of a family connection, separated through centuries by global hemispheres and the divergent paths of previous generations.

Kathleen Neill and her busy research staff do not give personalized guide service to seekers of ancestral links. In our case, Mrs. Neill became carried away by the enthusiasm of the hunt. She was impressed by Ruth's earlier correspondence, offering gleaning from the microfilmed records of the Mormon Church library in Salt Lake City and a family-shoebox find of a report by an Irish genalogist shortly after the turn of the century. She agreed to give up an afternoon of her annual holiday to meet us at the Guild research facilities in Belfast.

"It's much more fun to do the searching for yourself, with our help," she explained, handing over a thick sheaf of note and clues. "We can point the way, but we don't have the resources to take you to the locations."

Early next morning Mrs. Neill telephoned our comfortable farmhouse accommodations to ask how we had fared among the gravestones of coastal villages on the Irish Sea, the first targets on our list. Intrigued by a glowing report of several unexpected discoveries, she insisted, over my feeble objections, on volunteering her husband, as well as herself, for guide service.

"Don will be closing his shop at noon," she said. "When we have a free day, we usually drive into the countryside for a picnic. I'll just pack a bigger basket."

We had been braced for less than complete success in this venture a few days earlier on arrival in Belfast.

"Tracing American ancestry in most of Europe is his or miss," explained Robert Hall, chief executive of the Northern Ireland Tourist Board. "Nine out of 10 times it's a miss, and a wasted journey. But in Ulster it's more often a hit, because our public records office has done an excellent job of indexing old documents from here and also in the Republic of Ireland. Four or five visitors out of 10 actually find some kind of link," Hall said.

"The tombstone trade has come on most strongly here in recent years," he continued. "The reason is that so many of the Ulster Scots emigrated. There are 20 million people in American today whose ancestors came from Northern Ireland. And believe it or not, no less than 14 of your presidents."

American tourism to Northern Ireland this year is running at the rate of 27,000, down slightly from 1979 because of the U.S. economic recession, the tourist board official reported. Quoting from the board's annual report published this summer, he pointed out that the American figures represent a considerable comeback from the depressed decade after 1968, the start of the Ulster sectarian strife euphemistically referred to as "the troubles."

"While this is small beer in terms of numbers, in view of the bad press we've had for 10 years it's jolly good," Hall said. "Tourism is going up measurably. It's one of our few growth industries.

"Our increases were 27 percent in 1978 and 16 percent over that in 1979, both the highest recorded by any country in Europe. We recognize that any improvement over a very low base means a high percentage rate, but in fact we reached a total of 728,000 visitors last year. That is almost half of our entire population."

Hall saw benefits in addition to economic factors. "The influx of Americans, Canadians, British, Europenas and Irish from the Republic to the south brings hope. Ireland suffers from the awful curse of parochialism," he said. "As our people mix with visitors, they see that there's a lot more to the world than this small island and its troubles.

"The polarization of Catholics and Protestants was terrible a few years ago," he pointed out. "It has changed tremendously for the better. The increase in tourism helps batten things down. I haven't heard a bomb blast in three years from my office, right in the center of the city."

We had seen the residual evidence of the Ulster violence in the tight security at the Belfast railroad terminal, the street barricades in the downtown district, armored military vehicles patroling the civic center area and the electronic wand-frisking of shoppers entering the larger department stores.

But in four days of crisscrossing the city on various missions, we heard no sound of gunfire and encountered only one police roadblock, caused by a traffic accident on a heavily traveled motorway.

The only incidents of violence reported in a dozen issues of current regional and international newspapers we collected at every opportunity were of the variety common to any metropolis, including Washington, Detroit or Los Angeles.

There was evidence of another sort in the widespread demolition of the inner city. It was described as urban renewal, some of it inadvertently hastened by earlier intramural turmoil.

"Visitors get a dreadful first impression at the airport or railroad station," said Clair Metcalf, a tourist board representative. "But Belfast was never a tourist attraction. It always has been an industrial city, with all that that implies. You'll find it entirely different in the countryside." a

We did find a difference. All of the ancestral haunts we had pinpointed in advance were on the close fringes of the city. None showed even a graffiti sigh of Ulster's prime problem. The Ulster Folk Park, a reproduction of Northern Ireland structures and life styles in past centuries on the shore of Belfast Lough, not more than 10 miles from the central city, could well have been a pastoral setting from a more benign plantet.

"This is really amazing," said Kathleen Neill as we drove away from Joe Gibson's home in Ballygowan on the trail of Fort Hill Farm, Ruth's ancestral homestead in the nearby hills of Knockbreckan, a few miles south of Belfast. "To find an actual living relative is very rare. Mose people who come here searching for family ties are satisfied to find a few gravesites."

Neill smiled. "I would say you are extremely fortunate, except that you did your homework before you came. It mades quite a difference."