The new New York world and the old Washington world of Walter Washington mixed heartily last night as the new legal calling card of the former mayor was formally celebrated.

As 250 of the Washingtons' close associates sauntered into a two-tiered banquet room of the Madison Hotel, each geographical axis was impressed by a custom of the other. The Washingtonians marveled at the length of the spiraling receiving line, where 11 partners of Burns, Jackson, Miller Summit & Washington and their spouses lined up like the Rockettes. An hour into the party, after the receiving line was abandoned, one New Yorker said that New York business parties didn't have the looseness. "This is a simcha, a beautiful family party," she said.

Several of Bennetta and Walter Washington's worlds converged, with long-time personal friends Gladys and Todd Duncan; Washington's law school professor, James Nabrit, Jr.,; the City Hall buddies, Julian Dugas, Ben Gilbert and John Risher; local business leader Orlando Darden; Capitol Hill friend Sen. Patrick Leahy (D-Vt.) and ambassadors Guillermo Sevilla-Sacasa and Beverly Carter, all circulating. Bennetta Washington kept the guests intermingling by enbracing her old friends an then quickly introducing them to her husband's law partners.

The party was video-taped, at Washington's request, by Labero, the local firm that did his campaign commercials.

"Walter was very sympatico," said Sevilla-Sacasa. "The diplomats admired him very much and that rewpect and admiration will continue, I am sure." Arthur Burns, one of Wasgington's omnipresent establishment figures, came simply to congratulate, not to capitilize on old ties or new clout I doubt if we will have business together," said Burns, "but I will continue to like him as a great citizen."

Just the sweep of contacts, and his amiable personality, attracted the law firm of 60 lawyers, the majority based in New York, to make Washington a partner. "He's a giant and a leader. And a man of unduplicated experience," said Arnold I. Burns, a senior partner. "We do a lot of international law work-and plan toincrease it with Walter."