Making a plea for peace that was both colorful and somber, several hundred opponents of nuclear weapons marched from Lafayette Square to the Lincoln Memorial last night for a candlelight ceremony marking the 40th anniversary of the atomic bombings of Hiroshima and Nagasaki.

The marchers, in a demonstration timed to coincide with similar ceremonies being held in Japan, floated candles in the Reflecting Pool in honor of those who died in the Aug. 6 and Aug. 9, 1945, bombings. But the concerns of the demonstrators were very much about human survival in today's nuclear age.

"Disarm, disarm, disarm," Louise Franklin-Ramirez, a spokeswoman for the Hiroshima/Nagasaki Peace Coalition, which sponsored the march and commemorative services, shouted to the crowd gathered on the Reflecting Pool steps.

Many of the marchers had participated in a weekend of peace demonstrations, including a ribbon-tying ceremony Sunday that encircled much of official Washington with homemade banners depicting things their makers said they could not bear to lose in a nuclear war.

"We came with a busload of 49 for The Ribbon," said Kathryn Wisdom, 73, of Des Moines. "We want to stop the arms race -- eventually it will lead to a nuclear explosion, either on purpose or by accident."

Tim Yeaney, 26, a District resident who works for a consulting firm, said the weekend and last night's activities were the first demonstrations he had ever joined.

"I wanted to remember some of the lives lost . . . and I wanted to celebrate the life that is still with us," he said.

Stefania Sani, 32, of Kensington, carried her son, Ian, 2, along the march route and said she is a veteran of several nuclear protests. "I oppose nuclear war; the more [demonstrations], the better," she said.

At 7:15 p.m., 40 years to the minute since Hiroshima was bombed, the marchers observed a moment of silence in Lafayette Square and then heard an appeal for peace from Hiroshima Mayor Takeshi Araki, which was broadcast live from ceremonies in Japan.

"Humankind continues to face the threat of nuclear annihilation," Araki said through a translator. "Today's hesitation leads to tomorrow's destruction."

The United States dropped the first atomic bomb on Hiroshima Aug. 6, at 8:15 a.m. Japanese time. More than 200,000 people died in the bombings of Hiroshima and Nagasaki.

A highlight of the ceremonies was "The Adoration of Hiroshima," a carnival march staged by members of Project Mas, a group of performers from Trinidad and Tobago. Wearing skeleton masks and marching to drums and cymbals, the group led the procession to the Reflecting Pool.

The central focus of the carnival presentation was an 18-foot-high, white-plumed creation called Madame Hiroshima, which was meant to symbolize the bomb's mushroom cloud, and both the power and the horror of nuclear weapons.

Earlier yesterday, two members of the antinuclear group Greenpeace scaled a 125-foot construction crane on the west side of the U.S. Capitol and unfurled a 30-foot banner proclaiming: "A journey of a thousand miles begins with just one step. Stop nuclear testing."

The two protesters, who began the climb about 4:30 and came down shortly before 8 p.m., were taken into custody by Capitol Police and charged with unlawful entry.