Call it the battle of the light bulbs.

Defense attorney R. Kenneth Mundy invited the jurors in D.C. Mayor Marion Barry's trial to indulge yesterday "in a moment of levity" as he produced a light bulb the size of a softball -- as big, he said, as the one that Charles Lewis had said Barry unscrewed from the bathroom mirror and stuffed in his pocket after visiting Lewis at the Ramada Inn.

Lewis, testifying early in the eight-week trial, had drawn laughter when he said Barry was afraid the bulb might be a disguise for a surveillance device.

But Mundy set out yesterday to throw doubt on that testimony. "Try to put this in your pocket," he said, chuckling as he made a comic effort to stuff the bulb in his own suit jacket. "I am not exaggerating. The bulb doesn't exaggerate."

Assistant U.S. Attorney Richard W. Roberts was not to be outdone. A few minutes into his rebuttal argument, Roberts pulled a light bulb from his own suit pocket.

"I don't know why, but the defense did not bring in a prop like this," Roberts said, holding up a bulb only slightly larger than the standard size. Again, the spectators laughed. "Frankly, I have never seen a light bulb quite that big in a bathroom before, but I have seen one about this size."

The issue was not resolved in court, so The Washington Post turned to the Ramada staff for enlightenment.

"To be honest with you, I cannot shed any light on that," said a supervisor. "In some rooms we have large globes and there are some rooms that have regular ones."

When asked if a reporter could inspect room 902 and its bathroom lights, the response was decidedly negative. "That I won't allow. We are trying to put the whole thing behind us . . . . "

A moment later, though, the supervisor acquiesced and sent someone to examine the room's lights.

Ten minutes later, the verdict was returned. "It was the softball size," said the supervisor.