Lesley Stahl of CBS and Brit Hume of ABC were live on the air, trying helplessly to explain why George Bush was going to have a spur-of-the-moment midday press conference.

Stahl said she couldn't think of a reason other than new economic figures, favorable but routine."Down in front!" shouted photographers with still cameras as Bush came through the narrow door to the White House press briefing room.

"All harmony and light," said Bush, laughing at the commotion over the unusual appearance of a president in the small, crowded room. Ronald Reagan came to the room not more than a couple of times a year.

Bush's first press conference as president was a success with both reporters and the White House staff. For 42 minutes, Bush took questions, calling many of the reporters by their first names.

Saying he felt better than he sounded (a cold had made him hoarse), Bush was at ease and candid and seemed to have a good time.

At one point, as reporters were asking two and three follow-up questions, Bush said, "Stop the proceedings." Then he said the timeout would not come out of questioning time.

What he wanted to know, he said earnestly, was how he should handle reporters who won't relinquish the floor and keep asking questions.

Somebody shouted out, "Stay longer." Somebody else said, "Don't answer them." Helen Thomas of United Press International said that reporters should get one follow-up because the issue might be "left hanging out there."

With mock surprise, Bush said, "You mean my first answer is less than precise?"

Bush also made an effort to get past the first rows of seats where, by tradition, wire service and TV correspondents sit. "We have to get back to the Leubsdorf area back there," Bush said, referring to the next to the last row, where Carl Leubsdorf of The Dallas Morning News sat. Bush, who is from Texas, likes to make sure Texas reporters get taken care of.

At one point a reporter with The Boston Globe asked Bush if he would limit pay raises for White House staff members because of the budget deficit. Chief of staff John Sununu faked a frown and pretended to write down the reporter's name. Bush guffawed merrily, "He's a fair-minded guy."

At another point Bush looked down at the timer on the lectern. "It's 38:57:89. This thing is buzzing away up here. We've time for a couple more . . . I'm about to pull the ripcord on this."

Reporters, who went for months without a Reagan press conference, went away happy. So did the White House staff, especially spokesman Marlin Fitzwater. Bush's appearance meant Fitzwater didn't have to conduct a daily briefing, a chore he hates.

Fitzwater said that he, for one, hopes Bush holds more such sessions.