Air journeys in Africa always have an unreal quality. One sits, encapsulated, air-conditioned, sipping cooled fruit juice, gliding over the heads of people who stare up from the shade of their mud huts and have never thought to go more than twenty miles from the place they were born. They will live and die within sight of the same mountain. This is not to say that some Africans have not been great travellers. The eighteenth-century journals of writers such as Gustavus Vassa record journeys from Africa to the West Indies, Virginia, the Mediterranean and even the Arctic. But they also bear eloquent witness to the dangers and hardships incurred by anyone so foolish as to venture too far from that tiny area where ties of kinship and blood afford some protection. Most village Africans have a geographical knowledge that rapidly becomes mythical. In my own village no one had ever seen the sea and, at night, old men sitting around the fire would ask me repeatedly whether such a thing really existed. They were horrified at the mere thought of it and, when I described waves, swore they never wished to see such a thing. One seasoned traveller claimed to have seen it at the nearest city some eighty miles away and made much of his description of it. I never had the heart to tell him that he had only seen the river in flood.

It is difficult to know which way wisdom lies. What would Humphrey have done? Planes are sometimes flagrantly overbooked, especially during the holidays when schoolteachers sell off the free air tickets they receive on the black market. It is a bold man who lightly relinquishes a seat of which he is in possession. On the other hand, the half-hour would doubtless turn out to be a Central African half-hour and last considerably longer. A wise man might be availing himself of the limited comforts of the terminal rather than be sitting cooped up in a hot plane. I decided to try for the terminal. This might be the last time I would see a ham sandwich for many months. Alas, I had left it too late. The stewardess shouted at me that I could no longer leave the plane. It was forbidden. I should return to my seat at once.

We paused at the capital, Yaounde, before flying on to the central plateau where I would try to get a lift back to my mountain people. As the plane taxied to a halt, the stewardess explained to us that we could either stay on the plane or walk over to the terminal for the half-hour we would be on the tarmac.

West African air hostesses are far from the soothing, calming apparitions that haunt cooler zones. Perhaps they undergo the same training as Russian chambermaids and French concierges. They know that their principal duty is to keep passengers in order, to observe and police them. Above all, they are to be obeyed.

On a previous flight, one of my fellow passengers had whiled away such a stop by taking photographs through the open door, possibly accustoming himself to a new camera. It seemed that he was an employee of the company that had built the airliners used on internal flights and wished proudly to display images of his work in action in torrid climes. He was swiftly detected and denounced by a stewardess. There had followed a protracted row with a policeman who accused him of photographing strategic installations and his camera had been confiscated. This flight was more calm. The only distraction was provided by a small girl who was enthusiastically sick in the gangway. The stern stewardess obliged her mother to clear it up.

About an hour later, the other passengers returned with tales of refreshment and delight. There was, of course, no rush for seats. The plane flew on nearly empty, myself chatting to a young American Peace Corps worker on his way to a posting near Ngaoundere.

The Peace Corps is an organization that seeks to promote international understanding and goodwill by sending out its young people all over the world to work closely with locals on various good works. These may range from teaching English to constructing latrines. In Cameroon a number of Vietnam veterans -- still in their twenties -- devoted themselves to developing the wildlife parks. Large, hairy, gentle giants, they ranged the savannah on motorbikes tracking and counting elephants. The lifestyle of Peace Corps members might reasonably be termed "informal". Few return to the United States as clean-cut as when they arrive. Whatever contribution they may or may not make to Third World development, they undergo rapid personal change.

The Peace Corps house in Ngaoundere was always an agreeably ramshackle establishment with all manner of itinerants passing through, to or from the outside world.

The furniture had seen hard use -- not many Peace Corps members being of an inclination to flit around with wax polish. Multiple occupancy made it a place of certain dangers. The lemonade bottle in the fridge was as likely to contain photographic fluid as lemonade, the haunch of meat as likely to be part of someone's project on rat-poisoning in the slums as to be for human consumption.

One figure, who lived there for many years, still cast a long shadow. His passage was particularly marked by a strangely raffish animal skin that served as a runner on the scarred and scuffed sideboard. Intrigued by this object, I had asked one afternoon what it was doing in a house otherwise firmly dedicated to the elimination of inessentials. It seemed an odd frippery, like flounces in a monastery.

It seems that there was a man named McTavish. Having now been firmly ingested by local mythology, he is described as implausibly large and hirsute, of vast appetite and generous sexuality. So great indeed were rumoured to be his inroads into the red-light district that he is declared to have amazed doctors by the richness and strength of venereal infection to which he became host. This proved to be his undoing. He was repatriated and became the object of a medical-research programme. In Ngaoundere, however, his influence lives on. Many a budding friendship has withered on the vine when a young lady would remark to her Peace Corps beau, "I used to have another friend in the Peace Corps. His name was McTavish."

There was a hush. "Don't you know about McTavish's cat?" asked an incredulous voice.

McTavish's cat, the provision of food by its owner having become erratic, took to slaughtering the hens of the neighbours. They attempted to ambush it. It made large detours. They tried to snare it, it smashed their traps and continued to take their chickens. In the end, their protests and claims for compensation could no longer be ignored and McTavish promised to dispose of the cat. Tearfully, he resolved to do it with his own hands. The battle was long and vicious, the cat sneering at poison and avoiding with ease the bolts of McTavish's crossbow. It struck back, tormenting him with its cries at night. Finally, one sultry afternoon, McTavish cornered it behind the water tank. It knew its last hour had come but resolved to sell its life dear. The struggle was terrible but there could be only one outcome. The cat perished and McTavish retired to lick his wounds. The battle had, however, been observed by an employee of the electricity company. Seeing the cat was dead, he asked McTavish to allow him to eat its eyes, having been told that this would give him second sight. McTavish, never a man to turn down a new experience, allowed this. One thing led to another and a fit of utilitarianism seized McTavish. Good meat was scarce. He curried the cat and tanned the hide. It is not clear whether those who dined there that night were told what they were eating before they did so. So great was their rage at this culinary incest, however, that several were taken ill and friendships ruptured beyond repair. The remains of the curry lurked balefully in the fridge for a month, then were flung outside. Neighbours reported that they were eaten by a wild cat. Its fur had a green tinge.

Whatever may be the truth or falsehood of this view of McTavish, his presence is clearly enshrined in the cat-skin runner, now a cherished heirloom of the house. McTavish's cat -- its name is not recorded in the tale -- closely resembled its owner. The result of a cross between a wild tom and a domesticated female, it was large, evil, rapacious and lascivious. Witnesses describe it as having a faint green tinge to its fur, though this is not apparent from the runner.

The young American was not downcast at the tale of McTavish's cat, being creditably full of youthful enthusiasm and high ideals. He revealed that he had come to help construct fish-ponds on the plateau so that the protein content of the local diet could be improved. I remembered the case of another Peace Corps man who had previously worked on this project and concluded after several years that his principal achievement had been to increase the incidence of water-borne disease by some five hundred per cent.

Even on fieldwork, there are short intervals when not everything goes wrong. We arrived at Ngaoundere, said our farewells and I was able to gain the Protestant mission station without incident but with my luggage.

It is a mark of the seasoned traveller that he knows what to turn up with. In Cameroon, one does not bring a bottle of wine but a Christmas pudding and a large tinned Cheddar cheese. These assure instant welcome.

To my considerable surprise, my letter had got through to Jon and Jeannie Berg, my local missionaries in Dowayoland, and they had delayed their departure from the city of Ngaoundere to wait for me. We could leave for the mountains the next day.

As soon as we reached this point, it became clear that there had been changes. On my first trip, the road had been so full of rocks and craters that I had seriously wondered at several points whether I had turned off it in error. Now, the influence of the new sous-préfet, the representative of the central government, had made itself felt. The road was astonishing, smooth and broad as a new runway, a bright-red ribbon that cut straight through the bush. True, by the end of the rainy season it would again be rutted and eroded, but it was a shocking sign of optimism and endeavour in a town that had long reconciled itself to neglect and decay.

The drive was long and followed the usual pattern. As we got to the edge of the escarpment that divides the central plateau from the northern plain, there was the usual torrential rain and thunderstorms. As we descended the precipice, whining in bottom gear, the heat rose to a stifling hundred degrees and there followed the long drive along patched tarmac to the dirt road to Poli.

Like most West Africans, Ruben was crippled by chronic debt. This was not simply the result of shortage of cash in the face of consumer desirables. It is rather a traditional way of life. While Westerners groan beneath the burden of buying a house, Africans mortgage themselves up to the hilt to buy a wife. West African magazines are full of the misery caused to young men by the need to stump up large amounts of money and cattle before they can wed. Youth rails against the system but no one is willing to be the first to give his daughter or sister away for nothing. If he did so, how would he, in his turn, be able to buy a wife for himself or his son? And so it continues. Dowayos were always incredulous when I told them that "in my village" we gave our daughters away for nothing. One Dowayo of entrepreneurial flair but low ethnographic awareness asked if I could not have a consignment shipped over. We could marry them off and keep the bride-price for ourselves. It all seemed eminently sensible.

We pulled up at the mission station to a rapturous welcome from Barney, the Bergs' Alsatian dog, and a hardly less ecstatic greeting from Ruben the handyman.

At the end of the long haul down into Poli, there were other changes. In the market, scales were being used to weigh the produce instead of the rather impressionistic measures that had hitherto prevailed. Prices were clearly displayed. There was -- incredibly -- meat on sale. True, all this seemed to have served to depress the traders rather than raise their spirits, but there was an unaccustomed bustle about the place.

We went into a long routine of, "Is the sky clear for you?" "The sky is clear for me. Is it clear for you?" and more in like vein, the normal greeting formulae. But Ruben's heart was not in it, his eyes kept sliding to the rear of the truck where lay a brand new Nigerian bicycle, still in its wrappings.

As a result of marriage payments, Dowayoland is in a constant state of litigation. Payments are spread over many years and all a man's kin will be expected to help. Almost inevitably, at some time a man's wife will run away even if only to frighten him into submission on some matter of domestic strife. He will try to get back the bride-price already paid. His wife's kin will try to get him to complete payments. His own kin will ask politely what has become of their contribution, until he sees no way out. Unsettled debts will be remembered for several generations and inherited. Dowayos intrigue endlessly over these old scores. Like chess players, they have the ability to plan several moves in advance. The ultimate coup is to collect on a debt that was thought unenforceable. Thus, if A owes a cow to B who owes one to A's friend C, A may well give the cow to C and allow him to collect on an old debt that everyone else would have given up as a lost cause. B should have foreseen the danger of course and disposed his debts with greater skill.

It is impossible to live long in such a climate of raging debt without getting sucked into the system. I ended up in the debt of the mission. The chief was in debt to me but my assistant owed his wife money which she had lent to the rain-chief. All this made buying or selling anything fraught with difficulties as the money of the transaction was likely to disappear somewhere along the chain in liquidation of some quite different debt, incurred perhaps years before.

Ruben's own finances were as complex as those of a Swiss multinational corporation but yet he pined desperately for a bicycle. There was no way in which he could ever hope to save up enough to buy one as everyone knew exactly how much he earned and had allocated it in advance. So Ruben had come to a secret accord that instead of being given a rise in recognition of good service, he should be "given" a bicycle and his rise be withheld until it was paid for. This, of course, constituted a considerable interest-free loan but it also opened up whole new areas of debt and obligation that had not been foreseen -- at least not by anyone but Ruben.

Whenever Ruben's machine demonstrated temperament, he looked sad, sighed greatly and dramatically all over the house, generally transforming the atmosphere into that of a funeral parlour. Finally, it could be borne no longer and new parts would be supplied on credit, at which he would smile dazzlingly and fill the house with song. Somehow, he always managed to create a lingering feeling of guilt that he had been supplied with such an inadequate machine.

The chief quality of this particular model of bicycle, apart from its enormous weight, was the incorporation of a special sort of bolt. These were made of a curious alloy, possibly devised specially for this purpose. Be that as it may, they had the infuriating habit of simply twisting apart when anyone attempted to remove or tighten them. The result was a heavy trade in spares with the city some hundred miles away. Myself, the missionaries, the doctor and schoolteachers, in fact anyone who travelled, would be expected to act as a buying agency for spares. The model had been much altered over the years, the size of the bolts had changed, one could never be sure that any part would fit. Naturally the intermediary was held responsible for any inadequacies of parts provided.

It was only a matter of weeks before a Dowayo came to me in the village asking for a loan because Ruben had a way of getting spares but insisted on cash on the nail. I never enquired too closely into it, but I suspect that, for a consideration, parts could be exchanged between the clients' and Ruben's bicycle. The defective part was then displayed by Ruben as evidence of the unworthiness of the machine Jon had purchased. A replacement would then be rapidly supplied on credit by Jon, while Ruben enjoyed immediate payment and charged for the service. He had converted his bicycle into a bank.

But Jon's own concerns were far from Ruben's financial speculations. Undeterred by my own catastrophic attempts to coax the local soil to bear fruit, he had constructed a garden on the hill beneath his house. A system of barricades and entanglements had been erected to keep out marauding cattle whose tendency to "ravage" was proverbial. There sprouted melons, beans, peas, all manner of exotic plants beneath the passing gaze of wayfarers. Each paused to give his word of advice. Most predicted doom after the fashion of farmers the world over. But Jon soldiered on and the watering of the crops was an evening ritual that brought him deep satisfaction as well as blisters. As I had before him, he doubtless feasted in his mind on huge sweet peas and succulent squashes, and slavered as he laboured.

The sun sets swiftly in the tropics, giving way to deep darkness after a short period of twilight. A gibbous moon rose with indecent speed over the jagged granite peaks. Away in the hills, bright-red dots marked the places of bush-fires burning away the rank grasses so that fresh growth would follow. The heat, the susurration of a million crickets, the gentle moonlight, all made the verandah a good place to doze off. From the garden came the sound of Jon chortling gently over his swelling melons; from the backyard, the delighted chuckles of Ruben as he stroked the glossy black paint of his gleaming new bicycle, the first totally new thing he had ever possessed. In the kitchen, Marcel, the cook, wrestled despairingly in French with an English Christmas pudding and prayed for rain. It all seemed totally normal.