Washington reached a negotiated peace yesterday with visiting Soviet leader Mikhail Gorbachev, as the protectors and the protected settled with the rest of the city into a relatively good-humored, if inconvenient, routine.

On Day 3 of the Great Gorbachev Visit, police officers traded trinkets with KGB agents and the Soviet leader exchanged smiles and waves with onlookers on the street. The split-second timing of motorcades and men with radios took on the air of a ballet.

For the D.C. police department -- which is coordinating security with a half dozen federal agencies and the Soviet secret police -- the summit is a performance test, one they believe they are passing with pride as the world watches, officials said.

The city's elaborate security system got a test at 8:30 p.m. when a man called D.C. police from a Northwest pay telephone and said, "Gorbachev is a dead man."

It was the first telephone threat against either national leader since the summit began, said Capt. William White III, a D.C. police spokesman. The incident led to a police search near downtown, and four persons were taken in for questioning.

For some city leaders, the global spotlight of the summit is the first opportunity since home rule to show how well the District government really runs -- old-fashioned civic pride that, for many in this town, means racial pride as well.

"The city's leadership is providing an atmosphere of calm competence that has controlled traffic, controlled demonstrations, opened up and said, 'Welcome to Washington,' " Assistant D.C. Police Chief Isaac Fulwood said yesterday. "I'm proud of the city . . . . Everywhere I go, federal higher-ups stop me and tell me how pleased they are, and that includes the KGB."

Communists and capitalists agreed. New York developer Donald Trump, in town for yesterday's State Department luncheon with Gorbachev, said he was "impressed with the quality of the security job D.C. police have done."

Maybe it was the relief at the signing of the nuclear weapons agreement Tuesday, or maybe the sheer exhaustion after weeks of intense planning and four straight days of street demonstrations, but yesterday seemed to be the first day that this city grew accustomed to having the Gorbachevs in its midst.

Even the atmosphere around the general secretary seemed relaxed. In his first two days here, the white curtains on his colossal black ZIL limousine were drawn shut, and waving crowds along the motorcade routes couldn't catch a glimpse of him. But during several trips across town yesterday, the curtains were pulled back, and Americans caught his eye from the street.

"He waved and waved," said Jim Van Erden, 43, a federal employe from Fairfax County who was standing at 16th and L streets NW when the block-long Soviet motorcade zoomed by. "Give the guy credit: He's got PR." Added another man nearby: "He's warming up now. He's got to work the Americans."

Several blocks away, police briefly engaged in a somewhat tenser scene about 8:30 p.m. Police traced a telephone threat against Gorbachev, made to the city's 911 emergency system, to a pay phone at 1460 P St. NW. A man matching a description given by three people in a nearby van was arrested after a brief search, but White said doubts swiftly arose about whether the suspect actually had placed the call.

Jessroe Castle Martin, of 3728 Hayes St. NE, was arrested and charged with prison breach after police determined that a warrant had been issued for him in connection with a Nov. 27 escape from the D.C. Jail, police said.

Martin, who is black, was not charged with making the threat because a recording of the threat seemed to be made by a white caller, police said. White said the FBI and Secret Service had entered the investigation.

When police returned to the van, which had three white people inside, police said the occupants changed their description of the man they saw, this time saying it was a white man running from the phone booth.

Police then determined that the van was listed as stolen and all three people were taken in for questioning, White said. No charges had been filed by 11 p.m. and police declined to give the names of the people in the van.

The traffic jams that harassed motorists downtown earlier in the week eased up yesterday. Metrorail spokeswoman Marilyn Dicus said yesterday that the number of riders on Tuesday was up a "significant amount" from the previous Tuesday -- 490,000 from 475,000. But she said she didn't know whether that was because drivers have learned to avoid downtown during the summit.

White said that despite the large numbers of D.C. police officers assigned to the summit events downtown, the department's other divisions, including the city's seven police districts, are well staffed. He said the D.C. police's Operation Clean Sweep, the 15-month-old street-level crackdown on drug users and dealers, is continuing, "but not to the same level of intensity."

"Things are going as they usually would," Fulwood said. "There's no degradation of police work because of Gorbachev."

Besides the officers in the department's Special Operations Division, which handles special events such as the summit, most of the officers assigned to the detail are from administrative jobs and from such divisions as youth services, police officials said.

On Day 3 of the Gorbywatch, even the weather warmed up and the demonstrators seemed to chill out.

Since last week, a dizzying array of organizations had taken to the streets -- from the 200,000 who rallied for Soviet Jews on Sunday to the defenders of the Ethiopians, the Ukrainians, the Afghans and so many more.

But yesterday, controversy mostly stayed home. Except for the rally led by Christian evangelist Paul Wong in Lafayette Park, the location of choice for aggrieved parties moved to Foggy Bottom. There, about 20 people held a rally near the State Department, where Gorbachev was having lunch, to protest Soviet treatment of Christians.

The demonstrators staged a bit of guerrilla theater, with some of them dressed up in prisoners' stripes and the others playing the part of KGB agents. Each time a news camera crew approached, they enacted a scene in which the KGB men trampled on flags with crosses on them. But, on the advice of D.C. police officers, the actors put aside the plastic Kalyshnikov rifles they were using on the theory that the fake guns might make the real KGB nervous.

Officials have said privately that about 9,000 officers from a variety of U.S. agencies -- plus 135 KGB agents -- are working the streets of Washington this week, amid the tightest security in the city's history.

"Things are going very smoothly," said U.S. Park Police Maj. Richard Cusick, whose agency has most of its 575 uniformed officers working 12-hour shifts. "It's due to a lot of prior planning and our experience."

Training exercises and planning sessions among the various agencies began as soon as Gorbachev agreed a month ago to come here. "It really helped because we're all under different laws. We learn whose toes not to step on," said a D.C. police officer assigned to Raisa Gorbachev's patrol. "These motorcades seem smooth, but they wouldn't be without all this planning."

Behind the police barricades in front of the State Department, a virtual open-air market sprang up as security officials from the superpowers waited for a tardy Gorbachev. Police traded U.S. dollars for Russian rubles, and dimes and quarters for kopeks, police pins for soviet trinkets called znachoki -- gold- or silver-toned, button-shaped baubles embossed in red or blue enamel with images of Lenin, planes or the Kremlin.

D.C. police coveted the navy-blue, quilted trench coats of the KGB agents, Soviet flags and fur hats. The agents, who wore soft-soled shoes for comfort and speed, wanted the motorcycle officers' knee-high, black leather boots.

"Most Americans won't ever have a chance to meet a Russian citizen. These police officers are getting a chance to get to know them, to make friends. It's something they want to commemorate with a souvenir," Fulwood said.

But there was an edge to yesterday's relaxed atmosphere.

Nearly an hour before the Gorbachev motorcade left the White House in a slight drizzle about 12:40 p.m., police officers, donning full riot gear, set up their yellow police tape and cordoned off the area, often yelling at confused joggers or spectators if they stepped over the tape or tried to cross the street.

About 12:20, police cleared 17th Street for about two blocks in both directions of the intersection. Silence fell over the crowd, except for the static of police radios and the sounds of helicopters. Police officers were stationed throughout the area -- on foot, motorcycles and horses. Several officers could be seen pacing back and forth on nearby rooftops.

The eerie silence was broken at one point when a squirrel darted into the intersection where the motorcade was expected any moment, and several spectators yelled out, "Get behind the police line, squirrel." Laughter broke out from the crowd.

But mostly for the legions of security forces swarming the city, it was hurry up and wait.

"It doesn't get boring because you're constantly on the alert for something happening," said D.C. Police Lt. William B. Sarvis Jr. "Making history is always interesting."

Short sleep and long work days were a recurring topic in the bantering that went on among D.C. and U.S. Park Police as they stood sentry to the Soviets.

"Boy, last night was the shortest of my life," a middle-aged sergeant said to a young lieutenant. "I think it has something to do with not being 28 years old anymore. I'm 29 now."

Like most officers, D.C. Police Lt. Rodney D. Monroe said he had barely seen his family since the long work days began Saturday. When he got home late Tuesday night, there was a message from his 4-year-old daughter Hollye.

"It said, 'Daddy, I miss you. Wake me up when you get home,' " Monroe said yesterday, laughing. "Written backwards, left to right. You have to hold it up to a mirror to read it."

The mood was peaceful at the Department of Commerce Auditorium yesterday, where exhibitors eagerly showed off slices of Soviet culture, science, art and life styles.

An American youngster could be heard asking a tour guide, "Does everybody, like, have a phone?"Staff writers Karlyn Barker, Lynne Duke, David Hilzenrath, Sari Horwitz, Carlos Sanchez, Saundra Saperstein Torry and Linda Wheeler contributed to this report.