The groundbreaking for D.C's new convention center was held in April, but the fanfare was still going on last night.

The occasion was the swearing in by Mayor Marion Barry of four members of the center's board of directors, which he recently appointed. (The fifth member was out of town yesterday and had been sworn in earlier.) About 50 people munched cheese, crackers and peanuts in a conference room at the Martin Luther King Library before the formalities began.

The mayor expressed particular pleasure at the presence of "one person who has been a steadfast supporter of the city . . . and if we ever needed him we need him now . . . Congressman William Natcher [(D-Ky.)]."

Barry said that the swearing-in was being accompanied by a reception rather than being held "quietly in an office somewhere early in the morning . . . to demonstrate very clearly that we think this convention center is very important to the city. If we are successful -- and we will be -- we're not talking about people just coming and having a good time and leaving, we're talking about jobs."

He then administered the oath to Edward A. Singletary, who will serve as chairman, and to members Marie C. Barksdale (the only one to be kissed after being sworn in), John A. Boardman and Edwin Hoffman.

The mayor called on Natcher for remarks, saying that while the congressman "wasn't expecting this, politicians are always ready to speak." And Natcher proved the truth of that by launching into a pretty speech and winding up by telling Barry, "You have some problems, but you don't have a single problem that can't be solved."

Responded Barry, "You never know how well you're off until your well runs dry."