The small, frail-looking woman in the black dress emerged from the limousine moments after the hearse bearing the body of her husband pulled to a stop in the eight empty lanes of Constitution Avenue.

It was 6:03 p.m., and as Nancy Reagan stood in the evening heat, the throng packed along the avenue behind the White House yesterday began to applaud and then to cheer. "We love you, Nancy!" someone hollered.

She smiled faintly and waved as she held the arm of a towering Army general, and an honor guard carried the flag-covered coffin of former president Ronald Reagan from the hearse to a four-wheeled, horse-drawn artillery caisson.

Everything was crisp and on time. A riderless horse named Sgt. York, with a pair of the president's riding boots backward in the stirrups, bobbed impatiently. The pause was brief, and the former first lady was bustled back to her car. A man in the crowd bellowed: "God bless you, Nancy!"

Then, as the procession started for the Capitol, the broad, baking avenue was filled with the mournful cadence of drums.

They beat that curious, slow, interrupted rhythm that seems stuck in the national memory, a sound that echoes over decades and generations to grand Washington farewells of the past: to the mourning of John F. Kennedy in 1963 and Lyndon B. Johnson 10 years later.

Last evening, as in times before, the quiet between the drumbeats was filled by the clip-clop of the funeral horses' hooves, the roar of jets overhead and the bang of an artillery salute.

There was, too, a reverent wave of applause from the tens of thousands of bystanders stretching to the Capitol, and Nancy Reagan's small hand waving from a back window of her limousine.

Thus, on a warm June evening before throngs of perspiring citizens, was the former president transported for the last time to Capitol Hill, along the same streets and to the same sounds as other famed figures in an exquisite American ritual of mourning.

After his death Saturday at age 93, and after ceremonies near his home in Los Angeles, his body arrived at Andrews Air Force Base at 5 p.m. yesterday aboard a blue, white and silver presidential jumbo jet for three days of Washington leave-taking.

His coffin was lowered from the airplane and carried by members of an honor guard, whose crisp pants snapped in the hot wind out on the tarmac.

After Nancy Reagan made her way down the jet's red-covered stairway, and the honor guard eased the coffin through the open back doors of the hearse, the cortege left the base in Prince George's County about 5:20 p.m. for Washington.

Following a circuitous route through Southeast Washington, over the Potomac River and across the Memorial Bridge, the cars reached the 1600 block of Constitution Avenue, where the coffin was transferred from hearse to caisson.

The crisp maneuver took place with the Washington Monument just to the south and the genteel south portico of the White House visible across the freshly mowed lawn of the Ellipse in the haze to the north.

Bystanders had grabbed spots in the shade of the avenue's elm trees as early as 10 a.m. and were jammed up to 10 deep at 6 p.m. Many suffered through a 90-plus-degree day that was relieved only by a light southerly breeze, and by street signs advising that the avenue was a snow emergency route.

The National Weather Service said the mercury peaked at 92 at Reagan National Airport at 3:44 p.m. It probably got even hotter in the city, said senior meteorologist Jim Travers.

The procession, led by blocks of marching military bands, soldiers, sailors and cadets and an arrow-shaped phalanx of motorcycle police, headed east on Constitution, past street-light standards festooned with U.S. and District of Columbia flags.

Perspiring onlookers stood quietly next to their lawn chairs, behind black metal barricades that had been decorated with screw-on, bronze-colored filigree ornaments. Cardboard red-and-white no-parking signs were filled in with black marker reading, "State Funeral."

Hundreds of police officers, and at some points white-clad sailors, stood at ease every few yards along the way.

Past the massive tan stone facade of the Commerce Department building the cortege went, past the cool outdoor fountain of the National Museum of American History, where a small sign warned, "No Skateboarding or Roller-skating" and one of the city's new panda sculptures bore a presidential motif and a portrait of President Reagan on its right thigh.

John Beatty, 51, a real estate developer from Vienna, had staked out a spot nearby with his wife, Susie, 37, and children, Courtney, 9 and Carter, 5. "It's a once-in-a-lifetime experience," Susie Beatty said, "a moment in history. We wanted to pay our respects to a great man."

The procession made its way in front of the massive buff-colored columns of the National Archives, softened by flowering magnolia trees out front, and the East Building of the National Gallery of Art, where birds perched on the curving metal of an Alexander Calder sculpture near the entrance.

To the beat of the drums, and the strains of "America the Beautiful," the procession moved briefly onto Pennsylvania Avenue, and then back onto Constitution and under the gaze of a 1927 statue of Civil War Gen. George G. Meade outside the E. Barrett Prettyman federal courthouse.

At First Street, the procession started up Capitol Hill, shaded now by the oak trees that line the last few blocks of the avenue to the Capitol and frame the cream-colored dome.

Tom Woods, 41, had come from Cedar Lake, Ind., just to see the cortege pass. "I always liked Reagan," he said. "He just was a rock. I liked the way he handled himself and how he brought the country together. . . . We got the best seat in the house. Look at the view."

He gestured toward the dome, gleaming across the street among the trees.

A block away, David Bradley, 18, of Tewksbury, Mass., was wearing a red T-shirt that read, "Viva La Reagan Revolution." Bradley, a freshman at Boston College, had driven to Washington on Tuesday night with a friend.

Reagan "had such an amazing effect on the country we live in today," Bradley said. "He was a true American statesman."

The Katulich family from St. Mary's County was among those who set up blankets on the ground near Second Street. They arrived about 3:30 p.m. and planned to view the coffin in the Capitol rotunda after the procession.

"As soon as I heard about this, I knew we had to come," said Janet Katulich, who made the trip with her husband, Steve, and two children, Stephen, 13, and Amanda, 11. "There was something special about President Reagan."

Aaron and Amy Godeaux of Manassas and their four children, ages 4 to 10, watched the procession pass with their hands over their hearts.

"We wanted the kids to be able to experience it," Amy Godeaux said. "Ronald Reagan brought our country together, and our country came together again to say goodbye."

After the procession made its way up the hill toward the Capitol, where Reagan's body will lie in state today and tonight, Nancy Reagan slowly reached the top of the steps on the arm of Maj. Gen. Galen B. Jackman.

Her hair was ruffled by the summer breeze as they turned at the top to watch the pallbearers do their duty. Her face showed the weariness of the long day as yet another band broke into yet another rendition of "Hail to the Chief" and she cocked her head to one side, as if lost in thought.

Then the third artillery salute of the day began as members of the Army's 3rd Infantry Presidential Salute Battery fired three World War II 105 mm howitzers in Upper Senate Park, across Constitution Avenue from the Capitol.

At five-second intervals, the free-standing guns, fitted with 75 mm sleeves and four-foot barrel extensions, fired a 21-gun salute.

The sound caught many people by surprise. Scores had started to drift away, having seen and heard their piece of history pass.

Nancy Reagan waited patiently as the pallbearers made their slow ascent toward her, and, as they turned to pass by, she pulled the general forward, extending her right hand to touch her husband's coffin.