A thin piece of glass was the only barrier between three-year-old Patrick Johnson and 10,000 honeybees, buzzing industriously over their honeycomb. Undaunted by the milling mass, Patrick pulled his thumb from his mouth long enough to touch the glass, slip the thumb back in and scoot behind his mother's skirt.

Boy meets bee, just the way it's supposed to be at the county fair.

But the Arlington County Fair, held last weekend at the Thomas Jefferson Community Center, wasn't a great place to meet farm animals. The bees, eight two-day-old chicks, a couple of rabbits, a Sicilian donkey, a pig and a llama were there for petting, rather than the typical fair menagerie of horses, cattle and other barnyard denizens. Instead of tractors pulling blocks of concrete, politicians pulled for votes.

But it's an "urban fair," anyway, explained fair board member William Steel.

"The county is completely urban now, and that's why it was so hard to start this fair," he said of the five-year-old event. "But we had an excellent crowd this afternoon and we're doing just fine."

The fair was organized in 1976 by a nonprofit group called Arlington County Fair Inc., and the first one was held in 1977. Begun as a showcase for 4-H and Extension Service projects, this year's fair was overflowing with exhibits by craftsmen, citizens and civic groups.

As an urban fair, the three-day event drew an eclectic assortment of hawkers and displays. It was a good place to have your blood pressure checked, or to paint your face, buy a computer portrait, register to vote, chart your emotions and pick up free bumper stickers, buttons or pamphlets from a choice of about 80 civic or service organizations.

All 193 booths at the fair were taken, according to Steel, and filled with potters and police, rug dealers and Realtors, women's groups and woodworkers.

Kenneth Rosenberg, field training officer for the Arlington County Police Department, drew a steady stream of queries about his exhibit of locks.

John Caskey, an energy conservation specialist for the county, told people about the "one-stop energy center" set to open Sept. 14. But his red, white and blue "Energy Man" getup, complete with cape, obviously convinced the younger set that Superman was at the fair, and Caskey spent a good part of the afternoon explaining to kids why he couldn't fly.

The arrangement of booths made for some interesting next-door neighbors.

The Arlington chapter of the National Organization for Women, pushing ERA buttons and "Equal Pay for Equal Work" bumper stickers, had a booth next to the Ladies Auxiliary United Pentecostal Church display, where two young women were selling cookies, a leather-bound Bible and registration for a home-study Bible course.

A man in front of a booth advertising Dianetics, a psychological self-imrprovment method associated with Scientology, was hawking a "free emotional tone scale test." Next door, the Saint Coletta School was raffling off a seven-piece, white porcelain nativity set.

Overshadowed in the din and flashy booths was a line of tables and displays with baked goods and canned vegetables, fruits and jellies -- one of the few vestiges of more traditional county fairs. Red, green, blue, yellow and purple award ribbons decorated Mason jars of home-canned vegetables and fruit, slices of blueberry pie and flower arrangements.

Kathy Holt, who organized the competitive exhibits, said 400 participants entered in 500 available competitive categories, ranging from food to fabrics and photography to needlework. That left some categories without entrants. Holt said the most popular categories were horticulture -- including vegetables, fruits and flowers -- followed by baked and canned goods.

"We had a good percentage of first-timers, and that's very encouraging," said Holt. The best two entries in each category received awards worth $10 to $15, she said, and the two people who won the most points in the overall competition came away with pewter mugs.

Craftsmen and businessmen who came to sell their wares met with mixed results. Susie Reed, 33, selling macaroons, cookies and bread just outside the main entrance, couldn't keep up with hungry children crowding around her booth. But Barbara Prignano, sitting by the Grey House Potters small exhibit, wasn't selling much.

"We're mostly interested in adverstising, not selling," she said.

Meanwhile, anyone who couldn't find amusement amid the booths and exhibits could wander over to a constant flow of entertainment both inside and outside the community center.

At one point Saturday afternoon, four teen-agers in black, sequin-studded costumes tap-danced at one end of the hall, while the U.S. Army drill team twirled fixed bayonets outside on the concrete and The Kingsmen, a 12-man big band orchestra, played "In The Mood" out on the stage behind the center.

Fair board chairman William G. Malone said police estimates put attendance at the three-day event at about 45,000. Revenues from booth rentals amounted to some $8,000, Malone said. And while the sale of ads in the fair booklet took in roughly another $2,000, renting the community center and other expenses will leave between $200 and $700 to be used for next year's fair.

One of the few busts of the weekend fair was the hot air balloon. Frank Gallegos, who brought the balloon from Oakton, said there was plenty of hot air, but the tropical storm passing off the East Coast stirred winds over Arlington so much the air wasn't safe for balloons.

"I'll be back next year," he said.