The situation on Pennsylvania Avenue had been serious as a tractor parade snarled traffic well beyond rush hour Friday night. But by 10:30 that problem had evaporated. The weather, of course, remained hopeless in the true sense of the word -- nothing could be done about it.

All things considered, there couldn't have been a better time for a waltz.

That's just what the Smithsonian and Austrian Ambassador and Mrs. Karl Herbert Schober gave in the Grand Salon of the Renwick Gallery, the second annual fete in honor of the 200 Donor Members of the Smithsonian National Associate Program (those who had given the Institution $100 or more).

Rain pounded the top-hatted and caped guests as they scurried toward the etched-glass doors of the gallery foyer.

The red-carpeted stairway leading to the salon was banked with flowers and twined with ivy in approximation of the floral arrangements at the gallery's 1871 opening. Two liveried and bewigged greeters posted on the first landing delivered trumpet fanfare.

The first guests who tripped and drifted up the steep incline encountered strains of the Emperor Waltz, written by Strauss the younger to commemorate Emperor Franz Josef's first 40 years on the throne.

And oh, how they danced in the softly glowing salon: some swirling and dipping, satin and floating chiffon; others, not so daring or adept, relentlessly one-two-threeing around the floor to the tunes of the Gene Donati orchestra.

Evangeline Bruce, who had been dancing with Laughlin Phillips, pointed out to staff members that they should have more lights. "They've turned the lights way down, but in Vienna the lights would be blazing. We say there should be more lights." And there were more lights.

Frank and Jayne Ikard trailed Puffies as they waltzed around the floor. The silver helium-filled balloons had been the favors at Amie and Huntington Bloch's pre-ball dinner, one of 13 parties preceding the dance.

If there was some straying from the original waltz motif as the evening flowed on, it was recouped in the final cadence. As "The Merry Widow" shimmered through the gallery guests prepared to face the briefly forgotten rain that had been pelting the world outside all the time.