Attorney Howard Boros was just going into an office to take a telephone call yesterday when he looked out his window and noticed quite a large crowd on the street below. Then he saw Tommy Martin.

Martin, 41, "was hanging on one arm" outside the Bender Building at 18th and L streets NW, where only minutes before he and another worker had been washing windows.

The scaffold on which Martin and a coworker, Anthony London, 19, were standing broke about 2 p.m. yesterday and both men were left suspended by safety belts that dangled them several stories in the air over 18th Street NW.

London was rescued by fire-fighters who rushed to the scene of the accident. Martin was aided by the mechanical talent of the Boros & Garofalo law firm.

The windows of the Bender Buiding are designed to stay closed year-round, but employes of the law firm often work on Sundays when the air conditioning is not operating and thus had learned long ago how to pry them open for ventilation.

When Boros saw Martin dangling outside his fourth floor office, he and Mark Pestronk got a screwdriver, opened the window and helped Martin climb inside to safety.

"He was terrified," Boros said. "I'd be terrified, too. He must have been hanging out there close to five minutes."

"It's just remarkable we knew how to do it," said Pestronk of the window rescue. "The building superintendent didn't believe it."

Both Martin and London were taken to Georgetown University Medical Center and treated for minor injuries. Martin suffered rope burns on his right arm, and London suffered a cut in the elbow.

Fire officials, who said they were uncertain why the scaffold broke, later removed the collapsed structure from the side of the building.