He is apt to come whirring down the street, skating backwards, spinning in a 360-degree turn, his legs wide apart. He is off kilter, seemingly out of balance, and looks to be out of control.

Then suddenly, just before onlookers at 19th and M streets NW are about to bolt for safety, he stops instantly and skates off in another direction.

James D. (Big Jim) Allen is Washington's wizard on wheels. He is paid to please the crowd by the vendors who rent and sell skates at the popular intersection. They took one look at Allen's extraordinary ability and hired him to appear nightly.

He amazes the throngs of people of all ages and ethnic backgrounds who stroll amid the festival-like atmosphere. His acra-roller-batics, his leaps and blaring disco music add flavor to the area already known for its local restaurants.

Allen, who was hired a few weeks ago, got his reputation and his job because he makes rollerskates work for him. The 24-year-old deftly leaps, twirls and disco shuffles for the crowd. His friends say the vendors pay him because he has more "guts" than brains.

He was hospitalized a year or so age when he performed a 360-degree airborne spin and landed in the metal bars of the indoor rink where he was performing.

A maintenance worker for the General Services Administration by day, Allen appears at 19th and M between 8 p.m. and 1 a.m. six days a week, Tuesday through Sunday.

When he arrives at his four-cornered stage, he is prepared to entertain. A dazzled crowd soon gathers.

"They just like the way I skate," Allen explained in a classic understatement.

"I started skating, and people started watching and renting skates.After a while I decided to play some music, and more than 300 people were on the corner watching. The vendors had more business than they could handle on a night that was usually slow for business."

The rollerwizard, who often entertains small children-those who cannot skate-by picking them up and racing at breaknect speed down the sidewalk, is a performer at heart. "I get a real charge out of hearing the applause, and I like to make people happy," he said.

Allen said he practiced his spins and turns for nearly two years at roller rinks throughout the Washington area before he skated his way onto Washington's streetcorner rink.

He said he is often hasseled by police who see rollerskates as an accident about to happy. "They are always coming over and telling me the music is too loud or something."

As Allen performs his tricks; which often include leaps over people, motorcycles and chairs as well as riding limbo-style on one skate, he is constantly aware of other skaters, he said.

But only moments later, he was racing down the sidewalk backwards and barrelled into another skater. He was not hurt, and the other skater suffered a minor cut on his hand from a soft drink bottle which broke in the collision.

"Everybody falls when they skate," Allen explained. "Everytime I put on a different pair of skates, it takes some time to get used to them."

Allen is not always the only hotdogger on rollerskates. Just last week, Allen said, there was another skater who "tried to make a fool out of me."

"He saw me jump over one person. So he jumped over two. I jumped over four people and he quit. I knew I could jump over six people if I had to."

Allen, who describes other rollerskaters by the routines they can perform, belives he is more versatile than most other skaters who "appear" on the popular street corner.

Perhaps it is the city's evenings that contribute to a special comaraderie between skaters and pedestrians. The warm summer nights seem to entice and perhaps intoxicate pedestrians into donning skates and whirling under the moonlight.

Last week, 35-year-old Eivind Bjerke, of Bethesda, in his two-piece, plaid suit, laced a pair of skates to his feet and rumbled into the arena to the joy, amazement and laughter of the crowd. He and his daughter, who he said "dared me into it," struggled up and down the sidewalk with Bjerke falling into the crowd and laughing with them as he disco-skated the night away.

Donna Mcdonald, of Bowie, whose daughter was picked up by Allen and whizzed through the crowd of skaters said: "I came to Washington to go out to dinner, but this (the skating scene) is really neat. . .this is delightful."