The literary works of mid-Victorian explorers managed to make heroism monotonous. Between 1828 and 1880 at least 200 European travelers tried to cross the Sahara Desert, for example, to reach the then-unknown city of Timbuktu. Only one made it, and 165 died or were killed on the way; but their reports and diaries express a calm unconcern. They "were constantly thanking God for His mercies," says James Wellard in The Great Sahara (Dutton, $6.95), "never railing against Him, or anybody else."

They included people like the gallant Major Alexander Gordon Laing, who reached Timbuktu in 1826 despite 24 wounds and was murdered as he started home; Dr. Henry Barth, who spent five years in the deepest desert collecting scientific data; and Dr. Walter Oudney, a 32-year-old physician who died after (hiding the Roman ruins of Germa, lost for 12 centuries, "the richest archaeological zone in the Sahara."

Alexandrine Petronella Francesca Tinne, an immensely wealthy, beautiful, high-spirited girl of 17, fell in love with an English diplomat at The Hague, not knowing the scoundrel was married. Betrayed, she became a Sahara explorer. At 23 her scientific expedition into unknown land ended when her two German scientists died, along with her secretary, her two Italian maids and her mother and her aunt, both baronesses. Between expeditions she lived on her steam yacht, the only vestige of Europe she would have around her. Once she set out for Timbuktu with a personal caravan of 50 people and 70 camels. She was killed in 1869 at the age of 29 in a fight between quarreling tribes.

Wellard attributes the calmness with which people faced dangers to unquestioning religious faith profoundly stimulated by some mystical influence of the desert itself. Awesome antiquity is evoked by his account of the ruins of Carthage, where as many as 200 children at a time were sacrificed for victory in battle; or by Tassali frescoes, huge hillside paintings of men with mushroom heads and long gowns; or by the lunar desolation of land where wells were 200 miles apart and slave routes were lined with skeletons. Since Wellard alternates his evocations of the desert with his sketches of the people who braved it, The Great Sahara is inevitably a little diffuse, but it is made memorable by its startling facts, even more so by its unforgettable characters. And Wellard proves his case that the heroes were really indifferent to danger; the Sahara gave them that "sense of timelessness which transcends even the sense of mortality."