SPRINGTIME on Springer Mountain, Ga., arrived with a placid smile last year, mistiness warm on a Sunday morning at seven as I harnessed on my backpack and started north for Maine on the 2,120-mile Appalachian Trail. It would be summer, almost five months later when I reached my goal, the peak of Mount Katahdin and trail's end.

This primitive route, first blazed in 1936, is a pilgrimage along the paths of Colonial America. It strides the high spine of the Eastern Seaboard through the mountainous wilds of 13 states. It visits the deep forest haunts of our wildlife, the lofty air of hawk and eagle, the remote brush or bog of beaver, bear and moose. It often takes old Indian ways or winds along ever-reviving lanes of trillium, lily, violet and azalea. It treads softly through glades of balsam, springily along paths of age-old loam, awkwardly across stretches of cutting rubble and strenuously up stark battlements of boulders, glacial scree and granite.

Sometimes a foot wide, sometimes broad as an old wagon road, the trail traverses mountains, valleys, ridges, fields, old farmsteads, the forest and the country primeval with its ruins and rare scenery. At 59 and a portly 182 pounds, but with fair experience on a few Finger Lakes trails in upstate New York, I was happy to have a chance at this awesome but appealing trek.

The woods were old friends to me that first morning, their rugged brown face familiar and the prospect of their company inviting. Once under way, though, I panted a lot and rested frequently with a pounding heartbeat even on the easiest rises. But there were no demanding climbs, and at high noon I reached Hawk Mountain, a hike of 9.6 miles. A good beginning.

I rested, lunched lightly and drank plenty from the slim rivulet there. The atmosphere was quiet, the clouding day still accommodating. I had more than five hours of light remaining; should I try for Gooch Gap, another nine miles? From the inviting shade of a lean-to--the first of a variety of rude shelters that would become haven to me more than a hundred times--I gazed at the place I had all to myself. But then, I thought, what a shame if at the start I should waste such a fine afternoon. I never supposed it might waste me.

On the advice of Branley Owen, a Tennessee man who had marched the trail years earlier in 73 days and urged hikers to "travel light and make 10 miles before noon," I carried no tent or tarpaulin, depending on the shelters located at varying intervals along the way. Along Rock Creek about two hours later, I stopped to drink again and, from the clearing there, take a good look at the sky. Though the day was sweltering now, the sky seemed in a foul mood and, along the rocky lanes of rhododendron, it soon began to rain. I put on my pack cover and the parka of my rain suit. In a downpour 10 minutes later, I put on the pants. Now I would avoid a drenching but get thoroughly soaked in my own sweat.

By 5 o'clock the woods were dim, and the trail blazes, occasional splashes of paint to mark the way, had become indistinct. The heavy rains that puddled my glasses were making a muck of the trail. I had long since tired and was trudging laboriously, wondering how much farther I had to go.

Six o'clock: Stumbling now in the gloom, I came down a steep hill to a brook and was grateful for its cold water. Up again, a turn in the trail and then, in a few minutes, a glorious sight: A hundred yards ahead, there was Gooch Gap shelter and a roaring campfire.

The tepee of logs blazed heroically throughout the storm, but I had no one to thank. The mound of bedding in the corner barely stirred. After a hot supper and plenty of coffee, I put a note in his boots in case he left early. I was bushed and by 8 o'clock fast asleep.

That night about 11 the wind began to whine and the air to chill. Toward early morning the rain became snow. Winter had returned. At 8 a.m., as I started north again, the temperature had dropped to 20 degrees, the forest was dusted in white and the trail rimed with ice. I had dressed lightly the day before; now I wore insulated underwear, wool cap and mittens and a heavy jacket. My friend still hadn't moved.

My limbs ached but, warm and well rested, I was pleased at my 19-mile start. There would be plenty of climbing today, much of it steep. I had better settle for Blood Mountain, about 13 miles ahead. But no question about it now, I was really on my way to Maine.

Throughout the hike, I wore well broken-in boots with sturdy but resilient lug soles, and I carried a walking staff. The rest of my gear was sparse, practical: soap and a small towel, snake-bite kit, featherlight flashlight, camera, film, some yards of strong cord, a five-ounce aluminum cake-turner for a fire-grill, a bright aluminum pot that would soon be black, a two-quart water bottle, waterproof pack cover, notebook and pen.

The major weight was my foodstuff: thin spaghetti, a tin of corned beef, pound packets of oatmeal, raisins, peanut butter, block cheese, dried soups, nut chocolate, biscuit mix and--my one great luxury--real dairy butter. These staples would be duplicated in packages from home at rural post offices I reached every 10 to 15 days. I would treat myself with ice cream, pastries and chocolate milk at most every crossing near a country store.

A few days along in Georgia, I began to reach or be overtaken by nomad brothers bound north. Eventually this would make for fine times around the fire, as we traded goods and treated each other to our stories. I knew them by descriptive nicknames--Trailwalker, the Double Daves, Slackpacker, the Turtle, Dizzy and Rosebud (his banjo), Rocketman, Kelly & Borelli, Chawbrother--and they would become family to me, the Irish Goat.

Up into the Smokies on one sunny, windy day, and then on the heights, we faced the howl of the Arctic as the temperature dropped to 10. Water sources froze, and the wind scoured every ridge, toppling old trees across the trail while it staggered us with its grim force. To move in the open, we bent forward, waited for a lull and lunged. We ate snow, munched icicles and plodded on dumbly.

Windswept and pale, spring remained garbed in white. Not until May did we begin to enjoy its greening, its flowering and its warm sweet breath. Spring Beauties, those telling wildflowers, came into bud and into blossom on the Carolina slopes. Birds began to sing, but Chawbrother, who knew their songs, had gone on ahead, and I could only recognize the thrush.

Knowing mushrooms, though, I picked a few morsels, some early "oysters" (ostreatus pleurotus). I began to root in the trail side loam for the pungent ramp, that pearly little globe of garlic/onion that gave my common cooking a sharp lift. The mornings went by--and the miles; the long afternoon stretches and the aching succession of climbs were beginning to give me "legs."

I entered Virginia, where the trail stretches for 480 miles (longer than in any other state) and its Blue Ridge and Shenandoah pathways are almost all gradual. I covered the length in 26 days of perfect hiking weather (cool, clear, calm and sunny), averaging nearly 20 miles a day on a passage of endless delights. Bears ambled into the brush, untroublesome. Deer browsed by the shelters. The whippoorwill called in the twilight. Brooks and springs flowed with cold sweet water.

Hiking became a daily idyll. The trees were leafing, the wildflowers sprung up in fine variety, the warmed earth perfumed the air with its primitive musk, and flocks of birds and families of little animals seemed to find it as exhilarating as I did. I had worked 20 pounds of lard off my body, and oceans of fresh air had invigorated my legs and lungs. My heart no longer pounded, my pulse no longer complained.

Best of all, I was getting along.

By Harpers Ferry and the Chesapeake & Ohio Canal, I had put under my belt nearly a thousand miles of the Appalachian Trail, replacing the old belly there. Pennsylvania proved more a trial, though, than a trail. The going got tough again, all rocks, roots, rain and rattlesnakes; it was ragged, rugged going for more than 200 miles, half of it in chilling rain. My good old boots gave up, their stitching rotted and parted from the wrenching wet. The surface of my right foot, blistered then abraded from the bend and rub of the shrinking leather, became swollen and infected. I limped down into Duncannon, Pa., in pretty bad shape.

Here I had the good fortune to be "arrested" by Pat McCormick of the Harrisburg police force, who was out for a walk with his youngster, P.J. His wife Cindy soon came by, and in half an hour they had me settled in comfort at their hillside apartment where I would spend a lazy few days in well-fed and fondly doctored recovery.

Ah! the people you meet along the trail, not only fellow hikers but strangers in the towns, at campsites and out of nowhere.

Up into New Jersey now; then New York, Connecticut and Massachusetts: long, easier miles across fairly low country. Nearing the Green Mountains of Vermont, I often made 17 or 18 miles a day, getting up at 5, away at 5:30 most mornings, and hiking until the sun was low.

I had had a long vacation through the middle states. The trail would get serious, slowing me down with its long climbs. Here now was the hard work of the northern ranges. Coming down off Mount Cube in New Hampshire at eight in the morning, Jean Thomson, whose husband Meldrim governed the state for years, gave me breakfast at the roadside lodge of their maple-syrup farm.

This brisk, attractive woman, who had climbed all the mountains around, worried that I had no woolens to keep me from the coming chills of the high Presidential range and its icy monitor, Mount Washington. Leaving me in charge of the store, she went off to her home for a few minutes and returned with a roomy brown woolen sweater, the warmest garment I've ever worn. A week later in the cold and wind at Edmonds Col, between Mounts Washington and Madison, it kept me comfortable as a bun in the oven without a bit of other coatwear.

Way, way up on the map now, I was moving into Maine, into the central wilderness of its wonderful country, its cloud-making lakes, its moose and bear, its balsam air and bogs. I had managed the Green Mountains of Vermont and the White Mountains of New Hampshire. Now I crossed the Kennebec River at low water with the current swirling and rushing about me to my hips, threatening to send me and my backpack downstream to Bangor.

Soon I reached Monson, with a week to go to Mount Katahdin, the final climb of the trail. Still close were the Turtle, Trailwalker, Rocketman, Kelly & Borelli and Chawbrother, my companions all those miles. We rested, stayed, delayed, went on then as we pleased from the hostel there and host Mimi Eller, a "through" hiker herself in 1981.

Six days later, I slept at the foot of Mount Katahdin. Early in the morning, Aug. 7, after 140 days along the Appalachian Trail, I climbed its famous peak and stood in the sunny wind looking south. South to the length of earth I had come to know, to prize and to possess as my native property.

I was gaunt from my long travel and the hard life along that stretch of land. But I was elated with its loveliness, and I felt rich with the friends I had met, enjoyed and with whom I had shared. I had had the time of my life in the woods and the wilderness and the experiences of those 2,000 miles.

Deeply pleased with myself, I sat sort of dumbly on a picnic bench at Katahdin Stream Campground, sipped a beer and, in a way I cannot explain, felt close to tears. Some sadness, perhaps, that my great adventure was over, that my spirits must now return to plain life with its lack of exaltation. Some enlightenment or poignant inspiration in my life that I had been privileged to experience but now felt passing, leaving me, its compelling aim achieved.

I got a ride into Millinockett then, to the Pamola Motel, where I showered and scrubbed away the months--the sweat, the dirt, the woodsmoke, the caked mud on my boots and all my stained, worn clothing. The gracious folks there lodged me, fed me gratis and honored me with a great Moosehead beer celebration while the band, Peace of Mind, played on.

Next morning in the old world, I was homeward bound.