Country Fair. It's blue-ribbon season -- a time for horse-pulling, livestock judging, strolling the midway, and a ride on the roller coaster

THERE should always be two faces to any self-respecting country fair. There's the farmers' part: the prize-winning cow or dahlia. Then there's the midway -- you know, first the fried dough, then the roller coaster. The Topsfield Fair, an hour or so north of Boston, has both.

Topsfield claims that its fair is the oldest in the country (1818). While small, as fairs go, it's by far the biggest event in Topsfield, which isn't a very big place.

Along the midway here you can win a large purple stuffed animal through games of skill, or do a solid year's worth of screaming while hanging upside down on the SuperLoop. But you get a different impression of the fair, a more interesting impression, when you wander through the farmers' tents and booths.

``Hey, we're unloading pigs, lady,'' Dan Hurld, a tall, thin man in blue jeans, explained the day before the fair opened. ``C'mon, Rosita; c'mon Rosita,'' he coaxed, as an immense black pig strolled majestically into her pen, closely attended by 14 piglets. ``We've got everything here for you, kid,'' he said generously, pouring water in the trough.

Mr. Hurld has been doing educational demonstrations featuring farm animals for the last 33 years. In addition to Rosita and his Arabian mare, Kismet, he has a dairy cow he has worked with for four years. ``She kind of looks forward to it,'' he said. Also, sheep shearing and police dogs. ``That's very popular; the place'll be so jammed you won't be able to see the pavement.''

We returned to the pig. ``They're the smartest, pigs,'' Hurld said. ``Can't train 'em -- they're smart, but they grow too fast. What are you going to do with a 1,000-pound pig? They like to play; if you're familiar enough with them, you can see them smile,'' he said, bending over a small piglet.

``She'll be the most photographed thing in the whole place.''

The day of the grand opening dawned a bit chilly: a morning of orange trees against a gray sky. A hundred people or so were waiting for the parade, which was announced first by a blare of fire engines, then a distant thumping from the band.

``They make a big whoop and holler about it every year,'' said a man who was opening up a red-striped tent selling plastic blowup Kermits and Snoopies, and fudge.

Then the parade hove itself around the corner, led by the Waltham American Legion post playing The Battle Hymn of the Republic, followed by black-haired Mrs. Essex County, Christine Mclaughlin, waving from a convertible MG.

The Future Farmers of America, in a float pulled by a front-end loader, wereknee-deep in apples and pumpkins, and a supplementary tractor behind them pulled a handsome vegetable display. Several teams of draft horses stepped briskly by; then a woman in a tiny cart.

``That's Carlene White with her donkeys; definitely a strong addition to the parade,'' the announcer declared.

The most popular event at the fair -- and deservedly so -- was the horse-pulling.

The horses, their withers higher than a man's head, were harnessed together with a hitch on the back with a hole in it; the drivers had three chances to attach it to the sled of concrete blocks. This task was made more difficult by the fact that the powerful beasts surged forward as soon as they heard the smallest clink of metal hitch on metal hook.

The sun had come pouring out; when not competing, the drivers, short, stocky, tough-looking men in baseball caps, sat relaxing in deck chairs.

``Everybody quiet; let Ronnie do the drivin','' said the announcer, as two big bays circled the ring, prancing and struggling. The hitch crashed down; the drivers leaped back, the horses surged heroically forward with wild burst of effort, and 6,000 pounds moved. . . .

``Seventy-one inches,'' said the announcer, as the ground was raked smooth for the next entry.

In the cattle exhibition area, three black-and-white cows were being walked around the ring.

You notice at this point that it's not all that easy to walk a cow; it's not like walking a dog. At the end of each round, the contestants held the cows' heads up, to look as streamlined as a cow can possibly look. The cows looked as if they were merely enduring this.

``This boy and this cow just get along real fine,'' said the judge, awarding a blue ribbon. ``You can see that they've worked together for hours and hours.''

Another blue ribbon, in the novice category, went to a tiny boy and his exquisite Bambi-like calf; the joy on his face was undiminished by having been the only contestant.

Inside, in the 4-H building, last night's empty shelves were full of crafts and baked goods, already beribboned; organizers seem to have fallen on the sensible plan of having an award for almost everything.

In the fruit and vegetable building, a family was having its picture taken in front of the 303-pound pumpkin.

Outside, in the main ring, the sheep were being judged. ``This sheep is a short-legged sheep. That's not your fault; that's what you've got,'' the announcer said, laying it on the line. ``A little trimming over the dark area would have made it look a little better.''

In the main arena, a group of senior citizens was demonstrating square-dancing steps; the women swished their red-and-black crinolines as they danced to ``There's Gonna Be a Shindig in the Barn.''

After the dancers left, Mr. Hurld started up his Infamous Topsfield Pole Contest, in which people from the audience try to climb to the top of a slick metal pole.

``You can be in a tuxedo; it doesn't make any difference -- it's a clean pole,'' he said to possible contenders. ``When you make it, you get 10 bucks cash money.''

A teen-age girl jumped at the pole, hung on, then slid down with a loud shriek. ``Girl, you've got to go the other way,'' said Hurld. ``Make believe a bear is comin' at you.''

Finally, a gym teacher from Reading, Mass., scooted agily to the top, to great applause from the crowd. Then a black-and-white cow named Marie was brought into the ring.

``She's a foster member of the human race; she's a wonderful animal,'' Hurld said.

He then selected a massive, good-natured young man in a plaid shirt to hold the cow. Had he ever milked a cow before? He couldn't say he had. The cow, after all this advance publicity, seemed a less docile creature than one might have expected, getting out of her harness twice and leading the two men in a merry dance around the ring.

``What are you doing to me, Neil?'' Hurld said to the young man.

Finally, the cow, the harness, and milkers from the audience were all assembled. Neil patted the cow on the nose and said nice things to it, while the milkers milked to comments from Hurld: ``Don't unwind it.''

``Don't stretch the equipment.'' ``Hey, you come from the middle of Boston somewhere?''

And Boston, indeed, seemed far away.