The sound that drifts across Pennsylvania Avenue from Lafayette Park comes in quick, erratic bursts, each a high, shrill whine of protest against the labor that must be done. It is the sound of power saws held in the gloved hands of carpenters who have bundled themselves against the cold wind that sweeps across the park, slicing into the lumber that is assembled there each day now to be hammered into a recognizable form.

The carpenters, moving slowly under their heavy clothing, are painstakingly erecting the great reviewing stand in front of the White House from which Ronald Reagan, soon to be the 40th president of the United States, will watch his parade pass on his day in less than a month. From the front windows of the stately, white colonial mansion where he is spending his last few days, the 39th president can see the carpenters, measure their progress, and by it the time left to him.

This is a melancholy Christmas time for Jimmy and Rosalynn Carter. They are hard into the social obligations of the season. One afternoon last week the president shook some 1,300 hands as he said goodbye to some of the men and women who have worked for him and was photographed with each one. In the evenings, he and the First Lady have hosted the traditional Christmas parties, standing in the towering main hall of their home while a conveyor belt of anonymous faces passes by babbling the greetings of the season.

Merry Christmas, Mr. President. The temptation, just once, to reply, Bah, Humbug, must be almost irresistible.

But he hasn't given in to the temptation, not in public at least. His days remain busy, his aides insist, as he winds up work on the last budget he will submit to Congress, handles the other chores that must be faced -- including the business of the hostages in Iran that goes on and on -- and begins the preparations for his life as a former president.

Still, in the words of one official, "a kind of aimlessness" has settled on the White House, where it is no longer necessary to plot the affairs of state beyond the next four weeks. There is aimlessness for Carter's staff and an edge of sadness around him and what he touches. The sadness of the time and the man is unmistakable, and is commented on both by holiday visitors to the White House and those who know the place by now as well as their own homes.

What is really in the president's mind and heart as he comes to terms with his November defeat and contemplates his future may be known only to his wife. The loss to Reagan was a searing, personal setback for both of them -- she, even now, tends to show the scars more openly -- and to begin recovering from it in private they have spent 16 days since then at Camp David.

In the intervening weeks, he has witnessed, if he cared to notice, the brutal and public disappearance of Jimmy Carter as the country's dominating public figure. Reagan now commands the front pages of the newspapers and the largest chunks of time on the evening news, just as four years ago attention was riveted on the hamlet of Plains, Ga., while back in Washington Gerald R. Ford lingered in the twilight zone of the wrong kind of transition. Edwin Meese III, the incoming president's most important aide, commands the closest of attention from the listening media. One day last week Hamilton Jordan loaded his car with personal belongings and drove south to Atlanta for the holidays, unnoticed by the capital he left behind.

The words most often used now to describe Carter in private are "serene" or "subdued." While he remains busy, his pace, like those of others at the White House, has slackened, and so sometimes there are small, irrelevant diversions in the meetings over which he presides.

"His spirits are fine," said a senior official who sees the president daily.

"He's busy, still working a very long day. Now he gets to the office maybe around 6 in the morning instead of 5:30."

He is also spending large amounts of time thanking people for past services, making telephone calls to long-time allies, writing personal notes, sometimes seeing visitors who do not appear on his public schedule.

The president's aides remain extremely protective of him, denying the occasional suggestion that he is despondent, moping around the White House feeling sorry for himself. But they do not deny the sadness that is always around the edges of their encounters with him or the fact that recovering from only his second political defeat -- the first, in his 1966 race for governor of Georgia, by his own account almost crushed him -- will be a long, slow, painful process.

"There has been a perceptible improvement in his spirits," said one aide of the weeks since the low point immediately after the election. "Now he's developing a sense of how full his life can and will be. He's making a very natural progression from a very deep hurt to a kind of coming to grips with it."

Another aide, though, said he suspects there is some "gliding of the lily" by those who are closest to the president when they describe his spirits. "He's sad, too," he said. "He's not exactly a bundle of joy."

He is sad but not openly bitter, any more than his most senior aides are openly bitter, according to all accounts.

"Who can you feel bitter about?" one official said of the atmosphere. "If we had lost by 2 percent, there would be plenty of bitterness. But this way . . . . Bitterness needs a target. If you spread it thin enough, it comes out melancholy."

The president's men from Georgia move through these final days giving the impression that they are grimly determined above all else that they will end their stay with dignity and without rancor. One who knows them well, but is not one of them, sees in this a sign of their proud heritage.

"That's one thing the people of the Deep South know a lot about, at least in their own mythology -- how to be a gentleman when you have nothing else," he said.

So in the face of what one man called "some of these provocations," nothing has been said from the Carter White House. One of the instances he was talking about was Nancy Reagan's reported suggestion that the Carters leave the White House before Inauguration Day and move across Pennsylvania Avenue to Blair House so she could begin redecorating the family quarters. That left the White House speechless. When Nancy Reagan, on her tour of the White House, asked that the West Wing be cleared out so that she could see the working quarters without danger of bumping into a Carter aide, that brought a polite refusal from the White House.

There was also the quotation, attributed to the incoming president's son, Ron Reagan, Jr., that he would refuse to shake hands with the president because Carter "has the morals of a snake." White House press secretary Jody Powell, who is almost never at a loss for words and is a master of the cutting retort, was asked about that. But there was no retort. Instead, Powell, falling back on his quick wit and natural ability as a storyteller, replied:

"I suppose a word ought to be said in defense of snakes. I used to catch them as a kid. They're not bad animals. They're clean. They have little or no discernible odor and they almost never bother you unless you step on them."

The president is known to have reacted only once to all the Reagan hoopla that has overtaken Washington, and then in a fashion so typical of his presidency. It was after Reagan's initial "triumphal tour" of the Capitol, one official said sarcastically, when much was made in the media about Reagan's courtship of congressional leaders, how he was not about to repeat the mistakes of his predecessor in congressional relations. Reading and hearing that, Carter ordered his congressional relations chief, Frank Moore, to compile a record of all of his contacts with members of Congress, beginning with his transition four years ago. Moore's report is at the White House but not much in demand.

There was one other "provocation," but it did not come from the Reagan camp and it did produce a violent reaction. This was a newspaper column, written by Hugh Sidey of Time magazine, that began, "This time around let's have a little class," and went on to discuss the reappearance of "silver trumpets" and "white-tie-and-tails evenings" and "good Kentucky bourbon" in a Reagan White House.

Linda Peek, who was the press secretary of Carter's reelection campaign and is from Alabama, admitted later that the column sent her into a violent rage, provoking her to throw things against her apartment walls. Her reaction was perhaps extreme but not atypical. The Sidey column was the perfect climax to the four-year cultural war between long-established Washington and the Carter crowd, each smug and arrogant in its own way but now one clearly the victor and not afraid to crow about it. It was, said one southerner in the White House who spoke contemptuously of "Sidey and his ilk," part of that overall sense that may have gone out across the country that Carter had been "presiding over an administration of hillbillies."

And the column, for all it said about how one element of established Washington had really taken to its 39th president, enraged more than the Carter inner circle. Shortly after it was printed, the president hosted at the White House a reception for ministers to mark National Bible Week. He had arranged, as the afternoon's entertainment, an appearance by Clamma Dale of the Metropolitan Opera. Accompanied by a pianist attired in black tie, Dale transfixed the audience in the East Room that day with a stunning rendition of "America the Beautiful."

One of those who was present in the half-empty section set aside for the press was a reporter who also grew up in the South. He had long ago become disillusioned with Carter and the Carter presidency, and for much of the past four years had fought aseries of raging, screaming battles with Powell and many of the others. When Dale was finished and the applause had died down, he turned to a colleague and said, "I don't suppose Hugh Sidey would consider that class."

At some of the most poignant times, Carter has tried to handle the transition with humor, never his strong point in public.

"Welcome to the Blair House Annex," he said as he rose Monday night at the start of a private dinner for his senior staff and the members of the Cabinet.

The entertainment this night was a portion of Charles Dickens' A Christmas Carol, now playing at Ford's Theater, and Carter picked up the theme. Donning his glasses, which he wears only in private, he lifted an aging, leatherbound book and began to read. It was an excerpt from Dickens' American Notes, the author's account of his visit to America in 1842 and, more particularly, his tour of the White House when John Tyler, who would serve only one term, was its occupant:

"We entered a large hall, and walked through the rooms on the ground floor, as diverse other gentlemen (mostly with their hats on, and their hands in their pockets) were doing very leisurely. Some of these had ladies with them, to whom they were showing the premises; others were lounging on the chairs and sofas; others, in a perfect state of exhaustion from listlessness, were yawning drearily. The greater portion of this assemblage were rather asserting their supremecy than doing anything else, as they had no particular business there that anybody knew of. A few were closely eyeing the moveables, as if to make quite sure that the president (who was far from popular) had not made away with any of the furniture, or sold the fuxtures for his private benefit. "

Carter said he chose the excerpt to show that nothing much had changed inside the White House in the last 140 years. Secretary of State Edmund S. Muskie responded later with an eloquent tribute to him, ending with the traditional presentation to the outgoing chief executive of his chair from the Cabinet Room.

"We are giving you one of the moveables," Muskie said.

Monday night the president had read a second excerpt from Dickens about the White House:

"The suite of rooms on the ground floor, were lighted up, and the military band was playing in the hall. The great drawing room and the other chambers on the ground floor were crowded to excess. The company was not, in our sense of the term, select, for it comprehended persons of very many grades and classes; nor was there any great display of costly attire. But the decorum and propriety of behavior which prevailed were unbroken by any rude or disagreeable incident; and every man appeared to feel that he was part of the institution, and was responsible for its preserving a becoming character and appearing to the best advantage.

Dickens could have been describing the White House Wednesday night. The public rooms on the state floor were crowded, the music filtering out of the East Room, where the orchestra played light and gay. The occasion was the annual White House Christmas party for Washington reporters, not a constitutional obligation of the presidency but a tradition and expected nonetheless. So the Carters dutifully stood in the main hall shaking hands as the conveyor belt of guests passed them by.

It is said that in this process of coming to terms with his new reality the president has his natural ups and downs, his good days and bad. This was perhaps one of the latter. He looked to many tired and drawn, his eyes hollow, and when the obligation of the receiving line was over he and his wife disappeared to the privacy of the family quarters upstairs.

Comparisons and recollections ere inevitable, and many recalled an earlier Christmas party in the great colonial mansion. That night, the handshaking over, the Carters had drifted into the East Room and begun to dance among their guests. Soon they separated to dance with others, and the president was quickly surrounded by an excited circle of women who impatiently cut in on each other, seizing their chance to dance with him. Elsewhere on the East Room floor, Rosalynn Carter was twirled about by a succession of male partners.

No one complained that night that the Carters served only wine and egg nog. But that was a long time ago, in December 1977, when the shah was still in power in Iran and the prime rate stood at less than 8 percent. The president and his lady never danced again at their Christmas parties for the press.