EVERY WEEKEND this spring vast public picnics will be held in the countryside within easy driving distance of Washington.

These movable feasts usually take place on very rich persons' very nice estates, thrown open for the day to all comers who can come up with a couple of dollars for parking.

People gorge on elaborate lunches from the tailgates of stationwagons or simply spread a blanket for "dinner on the ground." Beer and wine and bourbon and branch water pass round.Wiffle balls and Frisbees wiffle and fris in the sunshine, and children pick up playmates the way a washed dog draws fresh fleas.

Also, they race horses from time to time during the afternoons, but the Maryland and Virginia point-to-point steeplechase circuit, which is what is under discussion here, seems as much an excuse as the reason for the outings.

This is not to say that the racing is not serious.

The riders take it seriously.

The owners take it seriously.

The knowledgeable spectators, most of whom are members of what is called the "horsey set," take it very seriously indeed.

A lot of the folks who park outside the ropes that separate the patrons' cars from those of the frolicking masses also take it seriously.

The point is that you don't have to give a damn about horses to have a good time. (If you take horse racing really seriously, there probably will be some discreet and illegal but honest bookies in the crowd, offering what are said to be very fair odds.)

This is the way it went at the Warrenton Hunt last Saturday, which is very much how it is likely to go this weekend at Potomac and Upperville and so on into summer:

A very presentable gentleman in a sweater coat stood at the entrance to the Clarke-Schlusemeyer estate, saluting the arriving patrons and relieving the casual spectators of $2. A little farther along stood an even more presentable gentleman in a red riding coat, whose function it was to separate the chic from the goats: straight ahead on the graveled road to patron parking, a right turn into a grease-slick pasture for the rest.

The cowpasture customers all immediately got stuck, but not to worry, two somewhat less presentable but very nice men on farm tractors casually dragged the cars into downhill getaway positions.

Within the pale where the patrons parked the ground was just as slick; the difference was that when the rear wheels of Mrs. W.H. duPont's Caddy began to spin, a veritable host of excellently presentable gentlemen leapt to her service: Full 15 yards of fine English tweed stood shoulder to shoulder along her front bumper to manhandle the car into place.

It's about time to stop making fun of the upper classes, because the point-to-point people have greatly improved their manners over the past decade. They still put "Mr." before the names in the race programs - even when the persons listed style themselves by nickname - but they're nothing like so snooty as they used to be.

In fact, they may now de described as friendly and generous to a fault: your correspondent could not ask a question without being offered something palatable to eat and something potent to wash it down. As the afternoon wore on, the scene began to take on a dreamlike quality, and no responsibility will be assumed here for correct spelling of names or accurate results of the races.

Oh yes. The races.

"Oh yes, there will be racing," said announcer Clay T. Brittle Jr. after the scheduled 1:30 starting time had come and long gone. "They tend to dawdle out there in the van area, but we nearly always get most of them to the starting line." He bent to the microphone and sent another gently phrased admonition racketing out over the loudspeakers.

Meanwhile, on the trophy platform on the second level of the grand grandstand, Mrs. John P. Cutting and Effi Fox and a nice young girl who got away nameless were arranging and polishing and rearranging a dozen silver loving cups and larger perpetual trophies and wondering what had become of The Beauregard Place.

"The winners get to keep the perpetual trophies for a year, but they are supposed to return them to us before race day, "Mrs. Cutting said with a severity softened by the knowledge of how hard it is to give up the symbol of such sweat and success.

"The horses are at the starting line, the flag is up," boomed Brittle, surprising everyone, for it was not yet sundown. "And they're off. . ."

All races had been cut by half a mile because of the sloppy going over just-thawed ground, but the five horses that went off in the First Colony Hurdle Series looked lathered and spent by their first pass before the grandstand.

"Damned weather," observed one railbird to another, "they just haven't been trained sufficiently."

"Could have done," rejoined his fellow. "I offered all of them my place down on The Coast."

Coast unspecified, but it sounded swell the way he said it.

At the finish it was Blue Nearco, Mr. Wm. Chewing up outlasting a game second effort by Second Call, with Sagitta fading badly and trailed by Kool Kake and Rector-Rue (whose name the cognoscenti pronounced Reeter-Rue).

Or so it seemed to your correspondent. "I thought that race was rather badly paced, didn't you?" he commented to a person who appeared to know what was going on. "They seemed full spent early on."

"I don't suppose you come to these affairs with any regularity, do you?' the person responded, leading y.c. to retire from the pontification business for the nonce.

The awarding of prizes was a perfunctory affair immediately following each event. There were no congratulatory remarks and no modest replies, just a hug and, maybe, a quick pop on the cheek, and the kudos had been kudoed. It was as though it were bad form to savor victory.

Five of the eight listed horses scratched from the second race, an open event for lady riders, which must have been some comfort to Liz Pearce, whose mount Sun Sign seemed in serious danger of being lapped in the 2 1/2-mile test.

Patricia A. Cassell's Never Delay, which she owns, trains and rides herself, lived up to its name, turning a 6:19 3/5 that was pronounced very fair considering the course conditions. Indian Act, which appeared to at least one pair of untrained - and increasingly unfocused - eyes to be the better-schooled mount, couldn't get it together in time to carry Betty Hughes to triumph.

Before and between the races y.c. fell into the charming and hospitable clutches of such patrons as, among others, as Mrs. J.A. Fernan, her friend whose name is irrecoverable from wavering notes, and a man who may have been Ernest M. Oare.

Each of these people was amply supplied with fine food and drink,which they were handing out as though we were left behind on the Titanic after the last lifeboat had pulled away. The racing continued through the afternoon, somebody said.