Four writers spoke yesterday at The Washington Post Book and Author luncheon of their tributions writing, having written, and trying again to write. There is, of course, nothing more interesting to fellow sufferers.

So while there were, no doubt, a great number of uplifting facts presented by the four at the Sheraton Park Hotel yesterday, facts wrested with great labor from archives and coded diames and dusty attics from locales ranging from right here in Washington. D.C. to the fabled coast of Turkey, it was nevertheless, the pain, the agony, the ecstasy, the thrill of the case, one made note of.

Abigail McCarthy apologized "for representing a sub-class of literature, the Washington novel." She said she had sworn, in Print, in a article years ago, that a good Washington novel could not be written. She has done just that, with her book, "Circles," which at the time of its publication by Doubleday she declared would be her first, and perhaps last novel. It is not, of course. She warned her audience that if she were to be seen wandering down Connecticut Avenue mumbling, it wasn't that she had flipped her pancakes. It was just another novel aborning, she said.

Alfred Friendly, former managing editor of The Washington Post, has written "Bearfort of the Admiralty: The Life of Sir Francis Beaufort," published by Random House. Vacationing on the coast of Turkey. Friendly found a 19-century book by Beaufort, an obsessive surveyor and chart-maker, which explained the region and charmed Friendly so that he set off to research the man's life. It took him to England, and then to Pasadena, Calif., where he cracked Beaufort's "schoolboy" diary code.

Friendly, who was with U.S. Air Corps intelligence in London in World War II, found the code concealed "what Monthy Python would call 'the naughty bits'" - including a Byronic, three-year affair Beauforhad with his sister.

Chalmers M. Roberts has written "The Washington Post: The First 100 Years" (Houghton Mifflin). "Most of you probably think," said Roberts, "that Richard Nixon took more lumps from The Washington Post than any other President." Not so, said Roberts. "Rutherford B. Hayes was the first presidential reader of The Washington Post (1877) and The Post never even acknowledged his claim to the title." Hayes was refferred to in these venerable pages as "acting President," "bougs President," and, most sweetly, as "His Fraudulency." He was said to be "trying to write a veto message with a corkscrew."

Moving quickly on, Judith Waldrop Frank described how it was that 100 agree on the final text of their Bicentennial project, "The City of Washington: An Illustrated History" (Knopf). She said she volunteered to take the enormous, five-years-in-the-works manuscript to New York "because I was the only one strong enough to carry it." There, a charming young editor at Knopf helped trim it. "All 100 of us," said Frank, "were friends and devoted to each other and we couldn't say 'That is the dumbest teacup I've ever seen. Why did you bring it to be photographed for our beautiful book?'"