In 1927, at the age of 22, John Hay Whitney became fabulously rich. His father had died, leaving the largest estate that had ever been appraised in America: $179 million. In today's inflated dollars, it is a stupefying sum. In the '20s, it was nearly unthinkable.

How does that weight of fortune press upon the human soul? What rigors of expectation and quandaries of conscience would beset a young man, especially one who, we are told, "was persistently nagged by a sense of owing some debt to society, by a search for the true dimensions of that obligation, and, above all, for a constant pursuit of what, for want of a better word, could be called excellence"?

These and a score of other crucial questions go resolutely unanswered in this large and lighthearted biography of Jock Whitney, celebrated horseman and intrepid bird hunter, former ambassador to England and last owner of The New York Herald Tribune.

Not that author E.J. Kahn Jr., a prolific veteran of The New Yorker, has been stinting in his research. Quite the opposite: Thousands of words are lavished on Whitney's possessions and parties, on the naming of his race horses, on his myriad and generous benefactions. We discover the shop where he buys his grouse-shooting shoes; the joys of his 18,000-acre estate in Georgia; the outlines of his acquaintance with Rockefellers and Vanderbilts, Robert Benchley, Joan Crawford and Tallulah Bankhead, William Paley and Walter Cronkite; the allure of his 76-room mansion on Long Island with its staff of 129; the substitute menu he provided for Queen Elizabeth when he found she disliked oysters.

Not that Whitney's life has lacked scope. He is the man who persuaded a reluctant David O. Selznick to buy the rights to "Gone With the Wind," helped Paul Mellon create the East Building of the National Gallery, hunted and dined with Dwight Eisenhower, sacrificed $40 million to save a dying newspaper and moved with ease in the most recondite conclaves of politics, industry and entertainment. Kahn recounts hundreds of such anecdotes with brisk and gentle irony.

Yet the man escapes us. The effect is akin to Giotto's frescoes -- a busy sweep and brilliant accumulation of detail, but lacking perspective. Kahn writes that he had "ready firsthand access" to Whitney, 77, whom he has known for 30 years. But at every significant juncture, Whitney's personality -- the character that it is the mandate of every biographer to convey -- remains nearly invisible, submerged in the welter of surface information.

To Kahn's credit, that surface shines. Jock Whitney's grandfathers had both been Cabinet officers; his father was an avid sportsman and exuberant materialist (he had a half-dozen homes and 28 cars, including four Rolls Royces); his mother, a legendary horse breeder, "the first lady of the American turf." From infancy, Jock was awash in a superfluity of privilege, with no obligations but to decide what to make of himself.

It proved a recurring problem. Throughout his life, he seems not to have been overburdened with strong opinions. He was an indifferent student and zealous athlete (as an oarsman at Yale, his hair style is said to have coined the term "crew cut") who during a year at Oxford danced the Black Bottom for the prince of Wales at his friend Fred Astaire's behest, "and -- 'to deafening cheers,' Astaire would subsequently recount -- fell flat on his face." He spent the bulk of his twenties and thirties toying with new companies such as Pan American Airways and Technicolor, backing Broadway shows, amassing a priceless art collection, disporting himself in "cafe' society," becoming an excellent polo player and courting Mary Altemus, a noted beauty. That marriage lasted 10 years, until 1940, when he wed Betsey Cushing, former wife of James Roosevelt, FDR's son.

There are hints, amid this socio-industrial dither, that Whitney had complex and peculiar feelings. Complex: When he proposed to Cushing, Whitney asked her if she wouldn't mind his first announcing a bogus engagement to another woman, a former girlfriend, because he felt it would help her in her dress business. Cushing indignantly refused. Peculiar: At the age of 34, we hear that Whitney " . . . his eyes filled with appreciative tears, put his head down on the back of the seat in front of him and murmured, 'Thank God.' " The occasion? He has just seen a few minutes of Vivien Leigh's raw screen test for "Gone With the Wind." And he seems to have been profoundly moved by the death in 1948 of his little Jones terrier, Chillie. He had the deceased canine memorialized in bronze, "and for the rest of his life had just two portraits on his office desk -- a photograph of his father and a statue of his dog."

But in general, Whitney's motives seem to have been rather pedestrian. He entered military service in 1942 because being a civilian "made him uncomfortable . . . almost a show of bad manners." On his first mission in the field, as a colonel on an OSS investigation, he was obliged to surrender and was held prisoner by the Germans in France for several weeks. Later, his amorphous altruism supported the humanities through the Whitney Foundation, aided the disadvantaged with fellowships for minority applicants and encouraged the postwar economy by a venture capital company. Meanwhile he reveled in his racing stables and determined to take charge of his life. But the major events of his next two decades were initiated by others: He was urged to become ambassador in 1956 after his superb fund-raising for the Eisenhower campaign; and the Herald Tribune came to him at the prompting of the financially pressed Reid family, which owned the paper. His ambitions for the Trib seem as vague as they were optimistic. Several years after buying the paper, and shortly before it folded, he was still writing memoranda asking "What is our basic editorial goal?"

The same question might be asked of this volume. After more than 300 pages of dense type, Whitney's character and apparent charisma remain a mystery. And of his putative pursuit of excellence, even Kahn is obliged to conclude: "He had not been an especially inventive or creative man . . . it seemed likely that he might best be remembered . . . as a symbol. He had epitomized, in a world of increasing egalitarianism, the vanishing patrician."