Both sides were satisfied with their ends of the bargain. The Potomac Appalachian Trail Club earned hiking privileges on a sprawling patch of wilderness near Gainesville, Va. in exchange for clearing three miles of nature trail there for use by Arlington County students.

The trail blazing, a public service project of the Potomac Appalachian Trial Club, began early on a recent Saturday morning at Phoebe Knipling's outdoor laboratory for Arlington schools.

Knipling, a retired science supervisor for Arlington schools, found and arranged purchase of the 200-acre Fauquier County site as a nature retreat and study area for Arlington students in 1967. Because the land is used frequently by Arlington students, Knipling decided trails were needed "to keep kids from getting lost and to preserve some of the natural vegetation," she said.

About 20 PATC members brought saws, clippers and weeders to the outdoor lab located just west of Gainesville. The PATC people called the clearing chore "recreational work." Anybody else would call it just plain work.

It had stormed the night before. The floor of the woods was lined with a thick carpter, of wet leaves. Humidity hung in the air so heavily the forest was like a greenhouse.

The PATC men and women sweated for about five hours as they cleared trails up and down ravines and around ridges beore returning to the lodge at noon for lunch.

"It's fun. Believe me, when you sit behind a desk fro five days a week, it's fun," said one new PATC member out on his first trail, blazing adventure.

They carefully cut switchback trails in sloping areas to minimize erosion, left leaves in their path and often cut around larger trees. The best indication to an outsider that a trial had been cut through the relatively open forest were the orange ties wrapped around the trees, tracing the trail that looped around the three-mile perimeter of the nature reserve.

"We try to leave things like they were as much as possible," said Tom Floyd, PATC supervisor trails, who has led trial building of crews on about 110 miles of trail in the Appalachian mountains. "This kind of trial is meant for nature study. It doesn't have to be as wide or straight as a trail meant for being distance hiking."

Besides, nobody wanted to alter very much the almost picture-perfect piece of property. The nature reserve contains meadows, forest, a fresh water spring, a lake and rustic cottages that make comfortable accomodations. There is a wide variety of plant and animal wildlife, and several Civil War landmarks.

"There's enough here to keep kids busy as long as they like," said Knipling, 67, who hiked the uphill route marked by the trailblazers. She said she wants to convert some of the trails into special routes for the deaf and blind and children confined to wheelchairs.

"There are different ways you can design these trails so that no child has to miss the performance of nature that goes on here every day," Knipling explained. "The PATC people have the know-how to build these trails, and we have the kids to use them."

As for the PATC members, building the trail was what they came for, and that was what they got. A whole day of "playing in the woods," as one member put it. A day of people meeting other people they never would have met ordinarily. Among the 20 trailblazers Saturday were a cab driver, a college economics professor, a physicist, a government administrator, a free lance writer, a librarian and a computer programmer.

"So it sounds a little crazy," said Jed Tucker of Arlington, a longtime PATC member who cleaned up extra brush at the tail end of the trail blazing column. "But for us this work is recreation; a welcome chance to get out in the woods. We accomplish another public service project, the kids get some trails. We have a good deal going as far as I'm concerned."