The moon sets at 4 a.m. somewhere along the 17,000-foot level.

The steep, slippery trail disappears into darkness, making the invisible path more treacherous and increasingly strength-sapping.

Our guide carries no flashlight or lantern -- as we had been assured he would by the tour agent. Missteps off the narrow route become frustratingly common; to pull a tired foot back onto the trail requires a draining lurch that explodes white sparks before eyes in a body starved for oxygen.

Far above are irrelevant stars, and seven miles to the east looms the dim hulk of Mount Mawenzi. Across the night stretches the vast East African plain, a felt presence rather than a visible landscape and pierced by not a single man-made light. cm,12p Rising directly above us as a blacker shroud is Mount Kilimanjaro, the highest point on this continent and our goal in a hike that began four days ago. The summit lies tantalizingly a third of a mile from us, but our arrival there -- if we make it -- seems light years away.

From the climbers comes only the crunch and slide of boots on scree, the hoarse gasp of thin air gulped through open mouths and an occasional cough. Sometimes the guide breaks into Swahili song, and once he does a fair rendition of a Swiss yodel.

We, the foreign hikers, say nothing except to call for a halt when altitude and fatigue threaten to overcome us. Headaches, vomiting and dizziness from altitude sickness already plague some of the party while others have quit the climb altogether. When we rest briefly, we beat our arms and rub each other's backs and shoulders to fight off the wind-borne chill that settles as soon as movement stops.

During one pause our guide emerges from the night and sits by me as I fight for breath and against the cold. Below, the long, black flank of the mountainside shows the satisfying distance we have covered in the three hours since our 1 a.m. start. But a glance at the summit is repaid with despair -- we must struggle far, far higher into ever-thinning air that already exhausts me and causes minor hallucinations.

The guide leans toward my ear: "You have dollars?"

A climb up Mount Kilimanjaro is a heart-pounding, tiring trek tempered with the satisfaction of sticking it out to the summit. It also is a constant reminder that this mountain is not only a grand and challenging peak for the nonprofessional climber, but a mountain that lies in the Third World -- where black-market currency deals are as important to impoverished Tanzanians as getting the western bearers of those precious dollars to the top.

At 19,340 feet, Uhuru on Mount Kilimanjaro is the highest point in Africa. However, it can be climbed by average tourists in good physical condition who possess no special mountaineering skills or equipment.

In the global pecking order of peaks, Kilimanjaro is nearly 10,000 feet lower than the tallest -- Mount Everest at 29,028. Under Everest is a large cluster of Himalayan peaks running down to the low 20s; there's the Soviet Union's top summit, Peak of Communism -- of course -- at 24,590 , and at 22,835 feet, Anconagua in Argentina is the highest point in the Western Hemisphere. Alaska's Mount McKinley is 980 feet taller than Kilimanjaro, but after it, Kilimanjaro looks down on most of the world's other mountains, including the Alps' Matterhorn, 14,700, and Mont Blanc and such well-known continental U.S. peaks as Mount Whitney (14,495), Mount Rainier and Pikes Peak.

Geologically, Kilimanjaro is a volcanic massif that consists of three principal dormant volcanoes, with Kibo (commonly known as Mount Kilimanjaro) the youngest and highest. It is linked by a saddle to the second, Mawenzi (17,564 feet) while the third, oldest and most worn is Shira, now a ridge reaching only to 13,140 feet. The creation of this mountain system dates back about one million years and it is intimately related to the Great Rift Valley that stretches across Asia Minor and eastern Africa from the Jordan River Valley to Mozambique.

In 1848, German missionaries were the first non-Africans to discover the Kilimanjaro formations and the Kibo (Kilimanjaro) summit was first reached in 1889 by a German geographer and an Alpine mountaineer. Since then there has been a steady stream of scientists, adventurers and, increasingly, tourists, to the top.

Ernest Hemingway brought some renown to the peak with his puzzlings over an expired leopard near the top and other manly musings in the vicinity. In "The Snows of Kilimanjaro," he wrote: " . . . as wide as all the world, great, high, and unbelievably white in the sun, was the square top of Kilimanjaro."

My wife Beth and I first saw Kilimanjaro 70 miles in the distance as we rode a bus down from Nairobi. The brown plains undulated through the heat apparently without end. Their immensity was scored by slow-moving herds of cattle, carefully shepherded by their nomadic Masai owners. The animals were strung across the horizon, some so far off they were mere moving dots, and yet Kilimanjaro still soared behind them. And because it rises as a single peak above low plateaus, its presence is more visibly dramatic than, say, the Rockies or the Swiss Alps where many mountains crowd the skyline.

We were in a group of six that also included two 19-year-old men from Bombay, India, and a French-Canadian couple who had just completed a two-year assignment in Mozambique. Our goal was to ascend Kilimanjaro in a four-day climb that would cover about 19 miles beginning from the park headquarters. Other groups -- ranging from two climbers and one guide to 10 hikers with as many porters -- were strung out along the mountain, some only hours ahead of us while others gasped near the summit as we strode through meadows two days behind them. Ample bunk space in the huts and on the mountain's broad flanks meant there was little crowding and lots of solitude, both at camp and along the trail.

*Day One. The 5 1/2-mile walk from the park gate (elevation 6,000 feet) to Mandara Camp at 9,000 feet takes three to four hours on a trail that winds up through moss-hung rain forest in which strange birds cry. The path is easily followed and our group spreads out at our separate paces. The afternoon heat soon forces us down to light shirts and sun lotion.

The porters toil among us, each with boxes and bags balanced high on his head. For some hikers it is unsettling to have a black African carrying one's food, wood to cook it over, bedding and extra clothes while they stroll unencumbered. Some of this guilt is absolved with tips and gifts of equipment at the journey's end.

As this first walk proceeds up Kilimanjaro's lower flank the most noticeable element is something that is missing -- noise. After the raucousness of Nairobi and other African cities, the silence is a balm that makes breathing seem a brashly audible sound.

At Mandara Camp there are A-frame quarters, a dining hall for hikers, lodging and a cookhouse for guides and porters, privies and water -- but there will be no baths until the return to Moshi.

Tea is served in the afternoon and porters scavenge for firewood to cook supper. Because Tanzania is a land of chronic consumer shortages, most of the food is in bulk -- whole potatoes and vegetables, hunks of meat, bread, meal and a few canned goods. And supper is mostly what was listed above: boiled potatoes and vegetables, tough meat, bread and honey and more tea. Some hikers grouse and demand more variety and higher quality.

During the meal one of the young men from India must lie down with a dizzy spell. Both are heavy smokers of American cigarettes and small pipes of hashish, habits whose effects are exacerbated by increased elevations.

Large bottles of Tanzania's excellent Safari Lager are on sale at the camp, carried to it by a woman who comes up the mountain every morning to gather reed grasses.

*Day Two. We are up at 7 a.m. for a breakfast of melon, fried eggs with much better meat and tomatoes, hot corn porridge, bread and honey and tea. For the noon meal on the trail we are issued more bread and honey and oranges.

The day's goal, Horombo Camp, is six miles away and 3,000 feet above us on a path that leaves the rain forest and opens into alpine meadows. Behind us clouds sweep over the trail while ahead the sun warms the mountain to create an enchanting isolation at a wavering edge between sparkling light and billowy shadow.

On the same schedule as our group are three others with hikers from various places -- Scandinavians, an American couple from the U.S. Embassy in Dar es Salaam, a Japanese, Germans.

The increasing altitude causes some shortness of breath; we slow our pace accordingly to reach Horombo Camp at 12,340 feet in four hours and 45 minutes. Others take well over six hours to cover the distance; the most important ingredient in making it to the summit is a pace that allows acclimation to the altitude. The hearty young fail as often as their elders because they tend to rush up the mountain only to find themselves laid low by altitude sickness.

Andre, 29 and one of the French-Canadians, arrives last and obviously suffers from the climb. A downward-bound Swiss hiker brings disconcerting news: A few months ago on her first attempt she and companions hired a guide and two porters at the park, but one porter and all their gear he carried never arrived at the first camp. Other hikers report some thefts from huts, mostly attributed to local folk who simply enter the lower camps and pilfer whatever is unattended.

Horombo Camp has what must be the most dramatically positioned outhouse of all time -- hung on the edge of a ridge that sweeps down sharply for more than two miles. Then clouds move in below the privy and isolate it above the white silence.

Safari beer again is on sale, but its price rises commensurately with the increased elevation. The evening meal is hot soup and another hearty stew. A bee found in the can of honey diminishes few appetites.

The Japanese hiker and the German couple have only a guide with them, so while we wait for meals to be carried in from the cookhouse they are busy with small stoves, pans of water and packets of freeze-dried food.

Andre complains of a headache -- another symptom of altitude sickness -- and goes to bed early. For urban dwellers, as most of the hikers are, the mountain's aloof stillness and lack of city activity can be as disorienting as it is soothing. Without lights, the 12 hours of darkness pass slowly with sleep using no more than half of them.

*Day Three. Andre remains ill and decides to await our return at Horombo while the rest of us push for Kibo Hut, six miles distant and 3,100 feet higher at 15,450 feet, from where we will make our final assault on the summit. We fill canteens at a spring starkly signed "Last Water"; from it porters also will carry five-gallon pails on to the hut, a waterless camp. They also must tote huge bundles of firewood as the landscape has become increasingly barren of large plants, much less trees.

We trudge past cactus-like groundsel plants and the oxygen-lacking air forces deeper breaths and a slower pace. The winding climb up the barren saddle between Kilimanjaro and Mawenzi is a solitary trek into whipping winds with the path stretching ahead to rock infinity. For breaks we take refuge from the chilling gusts behind huge boulders where there is a disappointing scatter of debris from those who have gone before. Appetites and thirst now abate, common and potentially dangerous effects of the altitude.

The steep unrelenting side of Kilimanjaro that we must yet climb gradually becomes clearer. We wheeze on toward Kibo Camp, the path appearing flat and benign in contrast to the faint trace of now-apparent trail zig-zagging up the seemingly perpendicular mountainside.

Kibo is a windswept, desolate camp of two cement block buildings and outdoor toilets. The hikers slowly arrive; a Norwegian already has thrown up; a German chatters with a chill -- both bad signs considering the heights and temperatures yet to be overcome.

Most of us zip into sleeping bags to wait out the long afternoon. The young men from India come with the news that Andre has gotten a porter to carry his pack and is heading for Kibo. He plods in late with a headache, looking even sicker, and goes directly to bed.

We get vegetable stew for supper and are urged to eat as much as possible to provide energy for the summit, but few have any desire for food. Instead we speculate about the last leg of the climb. We know many others have made it, yet as many fail. The major determiner is avoiding altitude sickness by not overexerting. "Remember the tortoise and the hare," advises the American from the embassy.

Yet the line between a normal altitude reaction and a more critical condition can be difficult to determine -- until it is too late. Even more serious than the agony of altitude illness is life-threatening pulmonary edema -- when fluid builds in the lungs -- with death likely if the victim is not rushed to lower elevations.

By early evening we all are in our bunks, but anticipation, cold and the lack of oxygen make sleep impossible. Whenever I doze off, my breathing slows from the deep gasps needed to pull air far into my lungs and I awake with a start, fighting for breath.

Andre vomits several times.

*Day Four. Our guide comes in at 12:30 a.m. with hot tea and briefly checks Andre, who huddles woefully in his sleeping bag. The rest of us stomp about, struggling to get into additional warm clothes.

At 1 a.m. five of us start out between two guides -- a second has been added for the final ascent -- on the loose, crunchy trail. A three-quarters moon glows over us, the wind is not strong and the pace is measured and slow. Suddenly, getting to the top seems within our reach.

In less than an hour one of the young men from India, cold and exhausted, quits and returns alone to the hut. His buddy then slows the group by frequent stops, so he is left behind with the second guide.

At this point, most of the enjoyment ends. For me, a pack mule mentality takes over, a process of unthinkingly putting one foot in front of the other. I recall forced marches in the Army; Beth later says POW treks came to her mind.

I stop looking at my watch, the water in our canteen begins to freeze. Our guide holds to a pace that now becomes too demanding and has too few breaks for my winded condition. We labor on, heads down -- a glance up from our dull gaze at the trail three feet ahead of us to the mountain high above brings a dizzying swoop of vertigo.

Discouragement deepens as we crawl to a halt after what seems a full night of effort -- surely the summit is just beyond the next turn of the trail. "The cave," the guide announces. Halfway.

There we catch up with earlier groups, and yet others bring up the rear. The guides share cigarettes and talk easily among themselves. As we set off again they continue to stick together, an arrangement comfortable for them but one that makes it tougher for us. Our small group of three hikers and one guide now becomes part of a string of nearly a dozen climbers and four guides. This in turn means each stumble or pause by those in front is magnified back through the rank into an agony of stop-and-start instead of an energy-sparing steady pace.

Then the moon sets and even senior guides -- ours has been to the top 500 times in the last 21 years -- pause to pick up the trail that merges into the dark mountain. Several times we are mistakenly led off the path and stumble and slide in the untrod scree before we gasp with roaring lungs back onto the route.

More and more frequently I ask our guide to slow down or stop; I complain about the lack of light that further slows our ascent. Beth, who has little difficulty with the altitude or the climb, points out that dispirited carping will not create illumination.

The slight-built French-Canadian woman has a cough and her light clothes and tennis shoes are unsuitable for the cold and the terrain, but she forges ahead with a faster group; the original group of six is down to Beth and me.

The final assault is a combination of unceasing scree and rocks to scramble over. Night slowly lightens, and over the clouds below and to the east a pink glow spreads and reddens. Dawn.

The jagged bulk of Mawenzi that for days reared above us is 1,076 feet below. We have staggered to the summit in the allotted five hours: Gillman's Point at 18,640 feet.

Others before us huddle and crouch in a wind-chill temperature well below zero. When I remove gloves to take photographs, my fingers go numb and one of the cameras freezes up.

We ask the guide about the final climb to Uhuru. I had expected a gradual hike along a well-defined crater rim for those final 700 feet. But we face more hard rock scrabbling for another two hours -- one up and one back.

Beth and I shudder in the wind; I have skewed depth perception and off-and-on hallucinations that alter the color and texture of the surrounding rocks. I think of hypothermia and pulmonary edema, both real possibilities and -- when suffered on the summit, as they are -- necessitating rescue by a team hours below at Kibo Camp.

In an instant Beth and I shiveringly opt for discretion and scrap one of the major goals of our African trip. We stop the ascent and turn back. We are joined by others who barely pause to look at Kibo's crater, glaciers and ice packs.

Others, though, continue to Uhuru, including the French-Canadian woman who later says she used her yoga training to convince herself that her numb feet were warm. She does not suffer frostbite.

The descent of Kilimanjaro is as unorthodox as the climb up was old-fashioned hard work.

Instead of zig-zagging down the trail we labored up on, most hikers "ski" directly down the slope, leaning back in their hiking boots and sliding toward Kibo Camp in a cloud of dust and rattle of rocks. Many make it in an hour -- an eroding practice that could become a serious environmental problem as more climbers come to Kilimanjaro.

We use the trail and pause often to take in the view across the top of Africa -- mostly clouds below us -- and to lessen the risk of a head-over-heels downward plummet. Not 500 feet below the summit the sun warms us, I'm breathing better and begin wishing I'd made a try at Uhuru.

Back at Kibo, Andre looks bad and is worse. With rattling breath, blue skin, lips and fingernails, he has become another victim of pulmonary edema. The rescue team is called; they give Andre bottled oxygen and soon they start the grueling job that is the only remedy -- hurrying him to a lower altitude. Andre is strapped into a heavy metal stretcher that has one rubber-tired wheel centered under it. A man at each end balances the cumbersome load and they start down the mountain at a trot -- passing jarringly but swiftly over trails intended for lone walkers instead of the rescue cart.

For the rest of us, a final reward is the descent from Kibo Camp. Beth and I leave at 10 a.m. with all day to reach Horombo Hut, where we will stay overnight. The pleasing difference is that we are now going down, and the air slowly becomes more supportive. More importantly, we can examine plant life, rock formations and long vistas unencumbered by the tunnel-visioning effort of climbing ever higher.

*Day Five. The final day is an 11 1/2-mile walk all the way back to park headquarters, but again with ample time to appreciate the varied climatic zones.

At the park gate we are given certificates that vouch for the elevation we attained. Although I did not reach Uhuru, I note with some smugness in the sign-in log that few persons older than my 41 years make the trek and not many that do get beyond Kibo Camp.

Without baths, and after much exertion in the same clothes for five days, Beth and I look forward to hot tubs at the Moshi Hotel, the only major hostelry still operating in town. Unfortunately, we have no reservations, and the official word we receive is that no rooms are available. We trudge back to the YMCA and its cold showers.

But from our window there is a view that reminds us our adventure was a privilege -- the broad, green start of Kilimanjaro's lower slopes, with the summit enveloped by clouds. Although now hidden from our view, Kilimanjaro's heights remain an indelible image.