`SAHARA' FAR FROM A DRY READ.

Byline: Richard Bernstein The New York Times

Title: ``Sahara Unveiled: A Journey Across the Desert''

Author: William Langewiesche 

Data: Illustrated. 302 pages, Pantheon; $24

Our rating: Three Stars

There are two kinds of travel writing. One is based on the places that most people would like to visit - what's doing in Florence or riding the ``Iron Rooster'' with Paul Theroux in China.

The other type, of which William Langewiesche's ``Sahara Unveiled'' is an extreme example, has to do with itineraries whose interest stems from their very undesirability: defined as being extremely uncomfortable, afflicted by climatic extremes and by buses that emit oily smoke and stale smells and break down in the middle of nowhere. But Langewiesche, a former commercial pilot who has visited the countries of the Sahara often, exploits the harshness, forlornness and political hopelessness of the vast desert to fashion an entertaining and edifying tale.

Langewiesche provides an aesthetic metaphor for his own long journey through the desert in an account of Timbuktu, the city in present-day Mali ``long famous for being far away.''

Centuries ago, we learn, word filtered back to Europe that this ancient stop on the caravan route was ``a mysterious and powerful city of native palaces, where the ruling classes ate on plates of gold.''

In the 19th century, a brave but unjustifiably self-confident Scottish explorer named Gordon Laing reached Timbuktu but was murdered by a desert highwayman before he could get home. ``He may never have admitted even to himself his only important discovery: that Timbuktu was not worth the visit,'' Langewiesche writes. ``The real Timbuktu was a sleepy, sandy, inglorious place, with only the faint traces of history to recommend it.''

Still, Timbuktu is on Langewiesche's route down the Niger River toward his final destination, which is Dakar, in Senegal. The ferry docked about six miles from Timbuktu: ``I was tired. I was sick,'' he writes. ``I caught a ride to Timbuktu proper, and by the skewed yellow lights of a Peugeot saw crumbling mud walls and the closed expressions of soldiers at an army roadblock.'' But then he returned to the river and the boat, which was leaving at dawn. ``I preferred to miss Timbuktu,'' he says. ``It has an attractive name, but is now known mostly for what it is not.''

In such a way does Langewiesche perform travel writing while not actually going someplace, even while, in not going, he tells us more than he could if he had gone. The truth is, ``Sahara Unveiled'' takes us to quite a few places that are famous for being far away, even famous for not being worth the effort to get there.

Langewiesche writes about them in a pleasantly lean and mildly sardonic way. He never complains, even when we know he is suffering. He also enjoys the considerable advantage of knowing people in these exotic locales, and his portraits of them are among the highlights of his account.

There is, for example, Malika, who now lives in Algiers, Langewiesche's starting point, though she used to live with her husband, Ameur, in Ouargla in the desert. Ameur, a roguish and unfaithful man with an amazing knack for friendship, was cruelly disabled in a car accident, leaving Malika with four children and no money. Langewiesche's succinct, delicate, finely tuned family portrait tells more about Muslim life today, about the relations between men and women and about individuality among cultural stereotypes than several volumes of academic lore. ``Sahara Unveiled'' is worth its price for Malika and Ameur alone.

Then there is Aissa, a vain, deceitful and vaguely menacing gunrunner who takes Langewiesche on a 500-mile journey by truck to the Libyan border. The supposed reason for the trip is the author's interest in viewing the famous ancient rock paintings of Djanet. Again, Langewiesche mixes a deft portrait of a local figure with topographical and artistic tourism - including an account of being stranded in the desert, not knowing if he had been left behind to die - to make up a savory tale with a surprise ending.

Here and there, Langewiesche fills us in on history: the natural history of the desert; the tribal histories of the Tuaregs, the original nomads of the central desert, and of the Haratins, the descendants of the Tuaregs' slaves. Other people also appear in this account, Malians, Mauritanians and Algerians. Langewiesche's journey took place amid two sorts of political disturbances: the battle between Islamic fundamentalists and the Algerian military, and a far less well-known struggle between the Tuaregs and almost everybody living on the periphery of the desert. And there is the Sahara, which is in its way the main character of the book, the lethal, indifferent, leviathan desert. Langewiesche writes interestingly of the nature of desert sand, drawing here on the work of a British World War I veteran named Ralph A. Bagnold, who spent years writing a book wonderfully titled ``The Physics of Blown Sand and Desert Dunes.'' We learn about dehydration and the biology of thirst, about the many varieties of scorpions and their natural history, about the techniques of driving in loose sand and about the economics of cross-border smuggling.

All along, as we visit places with names like M'Zab, Tamanrasset, Tchin-Tabaradene, Gao and, of course, Timbuktu, most of us will be glad that the intrepid Langewiesche has gone there, instead of us.

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