Laden with a library of booklets and magazines to aid me in making some sense out of the U.S. Open Championship Horse Trials. I made my way up the dusty trail to the Polo Grounds of the Myopia Hunt Club in Hamilton.

A pervading aura of manure seemed to guard the show grounds protectively, beckoning those familiar with its odor to come inside but warding off those not accustomed to it. I likened it to some delicacy peculiarly palatable to high society and rather than show my colors. I spent the day sniffing away as though I were savoring the bouquet of a fine brandy.

Still sniffing, I confidently entered the arena, and no one was the wiser as to my blissful ignorance of horses. Head down, scrupulously scouting the path before me for any deposits I could easily avoid, I ventured onward. First, a tour de stade: those continental expressions go so well with the equine scene.

"Excuse me." A chilly command from above froze me in my tracks. I had wandered smack into the path of a chestnut gelding and its charming 12-year-old rider, who was pert in her manner, precise in her dress and, in my opinion, a pain in the ass. I mustered up a feeble apology and let her trot by. The manure be damned: I raised my eyes and strode straight ahead.

Lacoste shirts and Villager dresses dominated the gallery, while riders decked out in the L.L. Bean's sporting look (or its equestrian equivalent) wore the healthy tans of leisure.

Groves of pines and evergreens outlined the expansive terrain of the polo grounds and little white picket fences defined the performing areas for the riders.

The three-day event was first introduced at the Olympics in 1912 under the name "The Military." The first day is the Dressage test which challenges the rider and horse to perform a series of some 20 tricky maneuvers, "to show the horse is calm and precise on the parade ground."

The second day is the Speed, Endurance and Cross Country event. It is defined to show "that the horse and rider could cross any terrain and surmount any obstacle to carry a message or scout a position." And while this cross-country steeplechase event is the most heavily weighted aspect of the competition, it is the final day's stadium jumping that draws the crowds.

The object of the stadium jumping is simply "to prove that on the day after a severe test of endurance, horses have retained the suppleness, energy and obedience necessary for them to continue in service."

By the time I arrived, Great Britain's Mark Phillips had already ridden. I was crushed. It was like going to a rock concert late and finding out the band had opened with one of the two songs you knew and liked. Princess Anne was to ride in another hour, though, so all was not lost.

The horse that everyone was focusing on was going through a series of trots and halts. I fumbled through my Ledyard '75 (the official name of the trials) handbook: move number 14, "serpentine three loops, the first and third true canter, the second counter-canter." Counter-canter, I thought sort of a ring to it, but what does it mean?

I continued my wanderings through a kaleidoscope of red, blue, green and black riding jackets. Exquisitely coiffured equines responded precisely to the gentle guidance of their riders' reins. Braided manes and brushed tails were only fitting for horses bearing names like Marcus Aurelius, Royal Core or Her Majesty's Arthur of Troy.

I continued past a row of concession stands run by the American Legion to the members only section of the bleachers. Here was the official luncheon spot for the habitues. Surrounding umbrella-shaded tables and a buffet line of noontime snacks such as beel bourgignon was a crescent of international flags. Ah, such tradition. I grabbed a hot dog and a beer from the American Legion and headed back to the horses.

I returned to the crowd of craning necks and clicking shutters just in time to see Princess Anne parade before the colonists. Her performance seemed relatively good with the exception of two mistakes accented by ooohs and ahhhs from the audience.

Despite what the purists may claim, the Princess and her husband, Mark Phillips, were strong crowd pleasers. Both are world class riders; Princess Anne won the European Championships in 1971, and Phillips is a goldmedal-winning Olympian. Early that morning. Phillips had marched his bay gelding, Laureat II, right into the lead of the Dressage competition.

As Arthur of Troy carried Her Royal Highness from the arena, the crowd settled back to its friendly tete-a-tetes. I proceeded to thumb through my "everything you wanted to know about the equestrian life but really didn't care to ask" handbook.

The honorary committee of Ledyard '75 was a near-exact replica of the Social Registry. From the Hon. and Mrs. Standish Bradford through the Davenports, the Hallowells, the Peabodys and Saltonstalls, to the pride and joy of Hamilton, General George S. Patton, son of Gen. Blood and Guts Patton himself. Hamilton even has a Patton Park or some such memorial complete with a bronze tank.

I reverently returned my handbook to my camera pack and decided to track down someone who could enlighten me as to what was going on. I corraled Paul D. Weaver, Assistant Director and Controller, who put the Dressage in layman's terms. "It's basically equivalent to the compulsaries in figure skating," Weaver said. "Sort of a cross between gymnastics and ballet that incurs negative points. The least amount of penalties amassed at the end of the three days will be your winner."

As a grey horse reared and refused in the center ring, the crowd groaned its disappointment: again it happened, and again the accompanying condolence. The horse obviously had no intentions of cooperating, for a third display of stubborness resulted in its early elimination. Polite applause and master and mare exeunt.

I felt obliged to pursue a course of royal inquiries with Weaver. The previous day the good Princes, and her husband had stormed out of a news conference, angered by a question as to whether "the accident of her birth" made her majesty feel different from her fellow British teammates.

Weaver said he felt the princess was not considerably different--"She's just regular folks," he said. "But she feels the spotlight to be an invasion of her personal life." He added that at a party earlier in the week in which almost all of the 300 people in attendance were thrown into a pool, the Princess was included.

A British voice booming over the loudspeaker cautioned the spectators to be quiet while the horse in the ring was performing so as not to disturb it. At the sound of his voice a number of horses behind us started up. I shook my head at the Catch-22-ness of it all.

The Dressage ended in a whimper and a whinney and I quickly headed for the Pintos and Mustangs in the parking lot and an escape from the overwhelming bouquet of the manure: bring on those gas fumes.

The next day was the meat and potatoes of the competition, approximately 16 miles of speed work, jumping and endurance. Dr. Dennis O'Keefe, mastermind of the stadium jumping course, explained some of the thought behind the design of a jumping course. "We're not out to get the riders but instead to present them with imposing inviting and jumpable obstacles," he said.

"The rider can go over the course alone prior to the competition, but the horse is seeing the jumps for the first time. Much of the success of the horse in jumping relies on the judgement of the rider as to the speed of the mount, the angle of approach and so on."

The cross-country obstacles were like a glorified miniature golf course. The jumps ranged from the traditional rail sense and stone wall to the dragon's mustache. Mark Phillips came to an unhappy end when his gelding three refused to clear the obstacle appropriately named the coffin. I stationed myself next to jump number 20, the swimming pool, and waited for the merry-go-round of horses to go by.

Pounding hoofs and the echoing of English accents filled the air of the Ledyard farm. Announcements traced the horses through the course for the gallery, and as one lady put it. "It's something like a golf match-you must be still near the jumps but otherwise you can wander at will."

The spectators were a bit startled to hear that "Better and Better had cleared the Normandy Bank (jump no. 16) and was travelling like a bat out of hell." But generally propriety ruled the day.

After a poor showing in the Dressage arena Princess Anne moved up to the eighth spot in the two-day standings. Another woman. American Beth Perkins, held the lead at the end of Saturday's gruelling event. Perkins, who early in the month had set a record low score for the Dressage, was riding high in the saddle going into the stadium jumping, and since she had been training for nearly a year in Hamilton, the local folk were mumbling much about Beth.

There are few sports in which women can so successfully compete against men on an international level, and so I asked Weaver what kind of qualities a competitive rider should have. "These riders are as solid as any athlete in any sport," he said, "You won't find any soft people pooping around on a horse. Riders engage in a good deal of running and they go out daily on anywhere from two to four horses to train. Oftentimes in the steeplechase a rider will dismount and run beside his or her horse. There is no sport I know of which demands as much presence of mind as in the horse trials."

Sunday there were some turnabouts, though, as Perkins fell from her mount just seconds from the finish of her show, dropping to eleventh place. Leading U.S. equestrian Bruce Davidson turned in a marvellous performance riding two steeds to top finishes. Davidson on Golden Griffen won the first place Atlantic Bowl, and also rode Royal Core to the third position in the standings. Only last year's winner Sue Hatherly from Great Britain prevented a one-two Davidson sweep. As for the Princess, she captured the last slot in the top ten standings.

After the last jump had been cleared and Sunday's addition to the 35,000 people turnout began filtering out of the polo grounds, I noticed the previously repugnant odor was not nearly as noticeable. Nor did I look with disdain at the gentleman, who with a most affected-sounding English accent said, "Say that was jolly good fun now, wasn't it?" Jolly good indeed.