On Friday night, the end of Lewis Dalton's first week of work at the President's Commission on Mental Health, the 27-year-old Capitol Hill resident and his housemate James Harper were walking from a friend's house at 127 10th St. NE.

Near the corner of 10th and Massachusetts, the two passed a man sitting on a brick wall in front of a row house. Harper muttered a quiet hello, and Dalton, new to the neighborhood, assumed that his friend knew the man.

But after they had walked several yards farther, Dalton recalled yesterday, the man yelled, "OK, you dudes, stop right there. Stop right there or I'll shoot you."

Harper jumped over the hood of a nearby car and sprinted across the street. But Dalton stood still. "I didn't know what was happening at first. So I stopped right there and then I saw the gun, and I said. "Oh, come on now, this is ridiculous, this is absurd." And I thought I could talk him out of it.

"I thought he was going to ask for money, but he never did. Then he said again, "I'm going to shoot you right now. I'm going to kill you."

The assailant pulled the trigger twice, but his gun failed to fire, Dalton said. On his third try the gun did fire and a small-caliber bullet struck Dalton in his chest, exited near his breastbone, striking his left hand and leaving three flesh wounds.

The assailant disappeared, and Harper rushed back to his friend, who was too stunned to realize at first that he had been wounded, Harper said. The two then walked several blocks to Capitol Hill Hospital, where Dalton was reported yesterday to be in satisfactory condition.

No one knows what to make of the incident which occurred at 10:45 p.m. Friday. "I just find it all rather strange, the fact that he didn't ask for money," Dalton said. "I had never seen him before. I had no explation, no real rationalization for what happened."

Dalton is not planning to leave the city, where he has lived for the last three years. "So far I can't see that I think I will consider not going out alone at night and probably look forward to putting a parking place in my backyard," he says, adding, jokingly, that he might build a tunnel between the garage and his house.

Harper found the incident "very bizarre." "You walk out of a friend's house and you walk down the street and someone says stop and you're shot at."

City police are baffled. "You usually don't just go up to a guy and say you'll kill him . . . it doesn't make sense," said police Sgt. Mike Kolonich.

Only Dr. Joseph R. Young, the senior attending surgeon at Capitol Hill Hospital, has found something certain in the shooting, nominating Dalton as "the luckiest man in Washington last night."