Crisp, autumn noon on 18th Street, between K and L.

Four-month-old female tiger, leashed, strolling with girl in blue jeans.

Glued-together automobile shimmies into parking space, conks out.

Chauffeur looking like the late Sir Charles Chaplin in his worst outfit, clambers from driver's seat, hits car with out-sized red mallet, green waters flood up from under hood . Explosion.

Well-known phiz of Abe Pollin, the town's Truest Believer in the Bullets and Caps, leaps out through quizzical-faced lunchtime strollers and free hotdog munchers to carefully positioned mike.

He's talking about Christmas.

Christmas night, its owner explans, his Capital Center will be the setting for Pollin's second try at becoming, besides everything else he is, the latest successor to P. T. Barnum.

Only, Pollin's going to do the reverse of Barnum, who parlayed Ringling Brothers-Barnum and Bailey into "The Greatest Show on Earth," which once had five, but now settles for three rings.

"It's going to be a one-ring circus, Europeen style," exudes Pollin, "fairer to performers, fairer to customers, who, with one ring, can see every trick.

"Christmas," Pollin goes on, "is family time. We'll have 19 performances between Dec.25 and Jan 7, during which we'll also have our traditional New Year's Eve concert and two games by the Caps."

This renewed "Circus America" venture for Pollin is very much related to the hockey team he's confident will yet be a winner and to basketballs' Bullets, who've that experience.

Both teams' schedules conflict with the usual spring visits of the Washington Feld Family's Ringling Brothers-Barnum and Bailey Circus.

Last spring's preempted dates, postponed dates and canceled dates wreaked havoc for athletes, circus people and civilians alike. To avoid another scheduling mess, Irvin Feld has bowed RB-B&B out of the Capital Centre in favor of the Armory for his traditional springtime circus. In 1978 RB-B&B will run at the Armory April 10-22.

So, with a covery of national circus authorities to help him, Pollin is reviving "Circus America," which prompted Washington's Great Circus War of 1974.

That was Capital Centre's first year and for various reasons Pollin and the Felds couldn't get together on leasing terms. So, Ringling Brothers went to the welcoming arms of the hungry Armory and Pollin created his own. Both opened the same night and after two weeks of battling, "Circus America" retired to oblivion.

Both the Blue and the Red editions of "RB-B&B" then moved into Capital Centre fall and spring. Two visits a year undercut the spring dates, normally the Big Ones. Last spring's scheduling debacle prompted another Feld-Pollin split; this time, both agree, entirely friendly.

For months 28-year-old Barry Silberman, director of the Centre's special events, has been trooping this country and Canada looking for acts which will live up to Pollin's boast that "Circus America's single ring will become the finest circus in the land."

There's been expert help Joe Bauer, known for his family's headline swaypole act, and one-time sports writer William B. Hall, have a circus-consulting firm.

Lined up are timeless Hugo Zacchini, "The Human Cannonball," The Great Wallendas, offspring of famed old Karl; Albert Rix, and his bears; the Leigh's Giant Space Wheel, and David McMillan and his Flying Tigers, youngest of which strolled 18th Street yesterday.

What's more, the ringmaster will be a 25-year-old female, Yasmine Smart, who grew up at her father, Billy Smart's Circus HQ near England's Windsor, which traditionally puts up a Christmastide tent to entertain the castle royals. Smart's ringmastering's been on both ABC and NBC.

"That's what I mean about Christmas," said Pollin. "We'll start a new Christmas tradition and then tour Circus America for longer runs to other arenas. The Bullets are champs. The Caps are making it, you watch, and so will Circus America.