The Toughest Man Who Ever Lived : DARK SAFARI; The Life Behind the Legend of Henry Morton Stanley <i> By John Bierman (Alfred A. Knopf: $24.95; 370 pp., illustrated) </i> : STANLEY; The Making of an African Explorer <i> By Frank McLynn (Scarborough House: $23.95; 411 pp., illustrated</i> )

In October of 1869, a “cruel, sexist, racist, degenerate, alcoholic” newspaper publisher--”a monster in the making”--received a young reporter in his Paris offices.

The reporter, painstakingly selected for one of the most harebrained commissions in the history of yellow journalism, has been variously described as a “half-mad, self-righteously brutal, paranoid, sado-masochistic professional liar.” On his good days.

His assignment, if he chose to accept it: to locate, in the shrouded center of an untracked continent, an itinerant, self-styled man of God, himself called “mendacious,” “violent” and “a colossal failure.”

In November of 1871, the search--perhaps the highest adventure in an age of explorer as superstar--culminated in a simple, somewhat fatuous greeting:

“Dr. Livingstone, I presume?”

The one-convert missionary, of course, was the eccentric David Livingstone.

The publisher was James Gordon Bennett of the New York Herald, a pampered, thoroughly unbalanced mogul who once terminated an engagement by urinating into the fireplace of his fiancee’s parents.

The journalist/explorer was Henry Morton Stanley, quite simply the toughest man who ever lived.

Together--and by way of wildly divergent motives--the unlikely trio engendered profound changes in the future of Africa, and indeed of the world.

Through the publicly scorned but privately scarfed pages of Bennett’s journal, Stanley relayed the “lost” missionary’s elemental message of base cruelty and bartered souls. The ensuing sensation played a major role in arresting, then eliminating the slave trade.

Conversely, Stanley’s dispatches and books led to the opening of the “Dark Continent” to the civilizing forces of 19th-Century Europe--a civilization from which Africa is only now beginning to recover.

None lived to see the mixed blessing of their collaboration. Livingstone died, kneeling, in his beloved Africa, his heart buried under a tree and his body--cured, dried and wrapped in bark--carried to the coast by two faithful servants in an astonishing nine-month trek. Bennett, having dissipated a $30 million inheritance, finally made his own obit page, to no discernible gnashing of teeth.

Stanley, whose two subsequent expeditions were perilous beyond the comprehension of our padded age, was buried in England under a headstone engraved in Swahili: Bula Matari (Smasher of Rocks).

It was Stanley’s favorite epithet--grander to him than his knighthood at the hands of Queen Victoria, grander than the medals and plaudits of a planet--but it was not enough. No honor would ever compensate for that other title, the one bestowed at birth in the registry of a Welsh village:

“John Rowlands, Bastard.”

It is the flaming rage between bastardy and burial--the combustion that fueled Stanley’s preternatural determination--that has lured biographers for more than a century. And as too many contemporaries learned at the side of Stanley, it remains a fatal attraction.

Two more authors this year, each with his own chutzpah, break their lances on the legend. Frank McLynn’s way is virtually a nonstop condemnation of the preposterous little Welshman, albeit a damnation delivered in slack-jawed wonder. John Bierman’s approach is easier on both writer and reader, a rousing narrative that makes Homer’s yarns look like spun wool.

Both authors agree in fact but differ in interpretation. The Stanley of McLynn, who finds a deviate under every hippo chip, is a latent homosexual of sado-masochistic outlet. Bierman’s explorer suffered from “innate sexual ambivalence” bordering on the prudish. While Bierman lauds Stanley’s love of literature, McLynn cavils at “a fetishist regard for books.”

Both agree, however, that Stanley’s implacable challenge to life was formed--calloused beyond balm--by a mortifying childhood, perhaps by one day in particular.

Stanley was born in 1841 to a Welsh servant girl (of “a degree of promiscuity bordering on amateur prostitution,” adds the ever-helpful McLynn). His father remains unknown, though it was certainly not John Rowlands, the town drunk who lent his name for the price of a pint.

Unwanted by any relative (least of all his mother), he was bounced among them until 1847 when the boy, barely 6, was told he was being brought to his Aunt Mary’s farm to live. Instead, he was deposited at St. Asaph’s workhouse. The iron gate clanged shut. No one ever paid him a visit. He remained there until he was 15.

If there was anything worse than being in an 1840s workhouse--with its attendant floggings, prostitution, sodomy--it was being a bastard in a workhouse. For Stanley: “Cain’s hellish mark was stamped on my forehead.”

Irrevocably scarred, permanently paranoid, terrified of women, the teen-age Stanley chose perpetual action over self-pity as his exorcist, his drug. Before he’d ever heard of Livingstone he’d packed the stuff of a dozen miniseries into his rucksack, all the while fabricating for himself not only a new name but a new history, a carapace under which his ignoble origins could cower in secrecy.

Once locked into his unholy alliance with Bennett, Stanley at last lit upon his raison d’etre : to out-explore any dandified candy-fanny who ever tracked a river.

For naked horror--clothed in suitably Victorian prose: “ . . . up to his neck in the Stygian ooze of the dreaded Makata swamp”--McLynn’s book is the chosen trail to Livingstone. Life on the road is enlivened by reptiles (“15-foot boas in the trees above, puff-adders and cobras on the ground below”), marauding cats, insinuating vermin, exotic disease, starvation. Stanley’s donkeys are eaten by crocodiles; tse-tse flies wipe out the caravan’s horses. (Stanley, typically, allows the flies to bite him to gauge their effect; typically, it’s the tse-tses that back off.)

Customarily hospitable tribes, rendered feral by Arab slaver raids, demand hongo (tribute), then attack anyway; Stanley’s “firesticks” exact tribute of their own.

At length, the party pauses on a hill above Lake Tanganyika, overlooking the sleepy village of Ujiji--to which Livingstone had repaired a scant fortnight earlier.

Historians continue to quibble over whether the good doctor needed to be “found” at all. Indeed he did, writes Bierman. While probing both the mystery of the Lualaba River (“the headwater of the Nile?”) and the location of local slaving depots, Livingston had been stranded in cannibal country. (“They eat only those killed in war . . . or bought for the purpose of a feast,” explained the missionary.)

The doctor was “a mere ruckle of bones . . . immobilized by foot ulcers, tended only by three servants” after the death or desertion of his party. Back in Ujiji, Livingstone had found his food and medical supplies looted. He always insisted that Stanley saved his life.

For his part, Stanley--after his painfully stilted salutation (always uncomfortable with his perceived superiors, “I couldn’t think what else to say”)--had finally found his “father.”

A transcendent intermission: Rations have been broken out, as well as Champagne hauled all the way from coastal Bagamoyo and uncorked in front of Livingston’s crude hut. The rough-hewn scalawags, as odd a pair of prickly, opinionated loners as ever trod God’s green footstool--swap jungle whoppers and literary quotes until the last bubble salutes a friendship forged in dreams.

Both got what he had sought and never really hoped to attain. Livingstone, who too often “had seen the long lines of men, women and children, chained together at the neck, on their Via Dolorosa to the coast,” had found a popular and influential pulpit for his anti-slavery gospel.

Stanley, tongue-tied and withdrawn when beyond his bailiwick of derring-do, was overwhelmed by Livingstone’s simple kindness, “though I don’t know much about tenderness . . . The consequence is that I have come to entertain an immense respect for myself . . . “

Stanley’s second expedition proves the Livingstone caper to be but a taste of on-the-job-training. Determined to complete the missionary’s attempt to trace the Lualaba, he steps smartly over the precipice of uncharted territory. The river, he finds, flows into the 1,000-mile Congo, a vast territory whose legends on ancient maps read only, “Here there be tygers.”

No tygers; only 56 miles of pulverizing waterfalls; mazes of flesh-rending thorns; flotillas of 80-oar war canoes; and always, day and night, the banks of the river ominous with the drum-drum-drum of manic bowmen and the cries of “Niama!” (“Meat!”)

Nearly three years later, a handful of tattered, bleeding survivors staggers into coastal Boma on the point of starvation, Stanley at their head. “Skeletal, hollow-eyed and with his hair turned white,” writes Bierman, Bula Matari nevertheless “found the energy to compose an article promoting the Congo River as ‘the great highway of commerce to broad Africa.’ ”

At this point, author McLynn abandons the narrative, himself exhausted by his considerable research; “Stanley” boasts more footnotes than a can of Dr. Scholl’s.

Bierman snatches up the standard, marching with Stanley on his third expedition, with its sordid side trips into insanity, hangings, cannibalism (one aide dispatches to Britain a pickled human head, to be mounted in his trophy case) . . .

The explorer who had almost single-handedly pried Africa open through force of will lives to deplore colonialism as “moral malaria.” Ever under the spell of Livingstone, he had come not only to love “his” Africans but to respect them as well.

Left sealed, however, is Stanley’s psyche, an enigma even--especially--to himself.

Richard Hall, in his “Stanley: An Adventurer Explored” (1970), claims, “This book destroys forever the image of Stanley as a ruthless conquistador.”

McLynn, calling Stanley “truly Napoleonic,” concludes that “to run such risks argues for a kind of madness.”

Bierman, who has written the best-balanced biography to date, claims to have found “the key to this complex, widely admired, little loved and deeply misunderstood man whose deeds transformed the face of a continent.”

The key to Stanley? Not yet. Not ever.