BESIDES ODYSSEUS has anyone ever led a more exciting life than Henry Morton Stanley, the English orphan who grew up to fight in the Battle of Shiloh, presume Dr. Livingstone, and discover the source of the Nile? Daniel Cohen's stellar biography suggests that the answer is a handsdown NO.

Even as a young man Stanley exerted a magnetic pull on close calls. He came down with fever upon fever while trekking through Central Africa but always insisted the worst case he ever caught was the Arkansas ague while still in his teens. Once on a riverboat he had to rescue his adoptive father from a knife-wielding intruder. He swam ashore from a shipwreck in Spain. One night in a Brooklyn boardinghouse he had to straddle a man all night long to keep him from killing his wife with a hatchet.

All of this, of course, was only prelude: Stanley's African adventures are sagastuff. On his greatest expedition, the one to confirm the Nile's origins, the figures alone establish the degree of difficulty. "Of the 359 people who had started with (him)," Cohen writes, "only 82 returned."

Stanley's celebrity will always rest principally on the famous greeting, "Dr. Livingstone, I presume," that he gave the long-lost missionary. No other remark in history so epitomizes British unflappability -- which was precisely why Stanley delivered it. Having spent many years in the United States, he was self-conscious about his lack of Englishness. He uttered the immortal anticlimax because he presumed it was what a proper Englishman would say. In later years he "could never fathom why others found the remark funny."

As depicted by Keith Ferrell, Ernest Hemingway is nearly as astounding a figure as Cohen's Stanley. What sets them apart from each other, however, is that the writer courted danger to prove himself and to write about it, whereas the explorer simply encountered it in the course of pursuing other goals. As a result Hemingway's bravery has something of the crass and artificial about it; his countless gashes, broken bones, and ruptured organs seem like backfiring play. Ferrell points out, however, that on several occasions Hemingway was spontaneously and genuinely brave, as when he rescued one of his sons from a shark.

AS AN ARTIST Hemingway prided himself on his integrity, by which he meant mainly his refusal to write commercialized stories and Hollywood screenplays like his friend Scott Fitzgerald. Yet the writer who smashes his path through Ferrell's book seems to have dissipated his independence in another, equally sinister way: by reducing literature to a contest with others and even with himself. Toward the end of his life, he was obsessed with writing a greater book than any of his previous ones.

The last part of Ferrell's book seems rushed. The author skimps on the post-Nobel Prize period and fails to cover the collective depression that afflicted that segment of the population which is fixated on its blood's redness when the nature of Hemingway's death -- suicide by shotgun blast -- became clear. But these are minor blemishes on a work that can hold its own with any introduction to Papa's life and writings.

Ferrell's Orwell biography is equally well- done, which is to say first-rate and up to the intelligence of anyone who ups age 11. And, indeed, Orwell lived a zesty life -- serving as a British police officer in Burma, fighting in the Spanish Civil War, scrounging around the slums of Paris and London. He managed the then-difficult intellectual feat of opposing both capitalism and Soviet-style communism. Just when, in 1950, his two great political novels, Animal Farm and Nineteen Eighty- Four, were making him a reputation as the modern Swift, his chronically weak lungs gave out, and he died at age 46. It's only in comparison with risk-devourers like Stanley and Hemingway that Orwell looks a bit pallid.