In a slurred voice on the night of the speech, Mr. Nixon tells Mr. Haldeman how much he regretted having to seek his resignation. He says: ''I love you. I love you like a brother. Keep the faith.'' The next day he is heard complaining profanely that Mr. Haldeman did not have the strength to submit his resignation and had to be asked for it.

While the newly released recordings provide little startling news, they add what historians describe as texture and heft to the record of Watergate and the Presidency.

''This is the transition between Watergate as a story for journalists to one for historians,'' Stanley I. Kutler, a professor of history, law and American institutions at the University of Wisconsin, said today. It was Professor Kutler's 1992 lawsuit seeking disclosure of the tapes that led to an agreement on today's release.

Visitors to the National Archives's modern annex in nearby College Park will now be able to hear what no one but the participants and a few archivists who logged the tapes have heard. Much of it will be familiar in substance, if not in precise detail: Mr. Nixon's use of swear words, often awkwardly inserted in conversations; his evaluation of aides, measured almost exclusively by their degree of loyalty to him, and the steady stream of bad news as Watergate looms ever larger. The Archives has not made transcripts, and the tapes are not available to be played by broadcast outlets.

Even if there are few surprises, the tapes provide a rich lode of information for both historians and anyone fascinated by the workings of the highest levels of the American Government during a crisis.

The taping system was installed in the White House in February 1971. At Mr. Nixon's request, the Secret Service put seven microphones in the Oval Office, five in the President's desk and one on each side of the fireplace. Two other recording devices were placed near the President's chair in the Cabinet room. A few months later, Mr. Nixon had more microphones installed, including one that recorded all his telephone conversations.

In his memoirs, Mr. Nixon said he had installed the system so his Administration would be ''the best chronicled in history.'' Many of his supporters regretted that he did not destroy the tapes once their existence became known.