Former Mayor Walter E. Washington joked ruefully a few nights ago about the limited facilities in the transition office he has occupied since Mayor Marion Barry was installed Jan. 2 in City Hall.

"Marion gave me a telephone with one line," he told the crowd Saturday night at the annual dinner of the Greater Washington Center Labor Council in the Hyatt Regency Hotel. "I gave him 12 lines, but what do you expect when you lose?"

Yesterday, Walter E. Washington, private citizen, sat in his cozily cramped transition office directly across Pennsylvania Avenue from the District Building he occupied for 11 years and pronounced himself at peace with the world.

"I just feel good," he said to a visitor. "I just feel good, that's all."

Armed with a telephone, a secretary and an oval wooden table, Washington has begun sorting through letters, memos, personal memorabilia and a mountain of other items he accumulated during his mayoral terms.

His office, borrowed space in the D.C. Office of Criminal Justice Plans and Analysis on the second floor of the Munsey Building, is his official transition office for the next three months.

In December, the City Council enacted last-minute legislation providing at least $25,000 and any necessary facilities for an "orderly transfer" of government to the Barry administration. The measure also specified a three-month phaseout period for both Washington and former City Council Chairman Sterling Tucker to wind up their affairs.

Much of the $25,000 already has been spent on the preinaugural transition activities of the Barry team. Budget office officials said yesterday they hope to stay within the $25,000 limit but may go beyond it with the Washington and Tucker phaseout costs in the next 90 days.

Yesterday, a steady stream of government employes and other wellwishers came by Washington's office, shaking his hand and chatting with him briefly.

Some still called him "mayor" and "your honor." Martin K. Schaller, Washington's former executive secretary, dropped in and joshed him lightly for not having a protocol office for handling visiting diplomatic dignitaries, as Barry has proposed for the new administration.

Wearing a smartly tailored gray pinstriped suit, Washington said he has had three separate requests for his official papers and is considering writing a book about the 1968 riot period in the city.

He said he is considering requests for his papers from the Library of Congress, the Lyndon Baines Johnson Library in Austin, Tex., and a third institution that he declined to identify.

The Library of Congress request is recent, he said, but the LBJ Library request is "long standing." President Johnson was instrumental in fashioning the District of Columbia's 1967 government reorganization act -- a precursor to the city's home rule charter granted in 1974 -- and appointed Washington as the city's first mayor in almost a century in 1967.

Asked if he plans to write a book, Washington said he is considering a book about the riots that erupted here in April 1968 with the assassination of civil rights leader Martin Luther King in Memphis.

He said records of the D.C. Office of Emergency Preparedness, which as the mayor's command center maintained detailed notes on the course of the riots, were deposited in the city library system by recently retired emergency preparedness director George Rodericks.

"I'll be looking at that material very carefully," Washington said. "It's good history... I suspect I have the makings of a book."