AUTOGRAPHS of two presidents, Harry Truman and Ulysses S. Grant, recently sold in New York for $150 and $350 respectively. At the same sale it was possible to purchase signatures of Bernard Shaw, Igor Stravinsky, P. T. Barnum and England's Queen Mary for under $200.

But an autographed photograph of Jerome Kern went for $365.

Surely this would have amused the composer of "Show Boat," one of whose several celebrated book-and-autograph collections sold for nearly $2 million 50 years ago.

"Ol' Man River" keeps rolling along (a production of "Show Boat" opens May 27 at Wolf Trap) and, if Gerald Bordman has his way, so will its creator's renown.

Bordman is the man behind "Kern: The Magic Melody," which sold out three early-May performances in the Smithsonian's Baird auditorium. He recently presented a New York "Showcase" revival of Kern's early smash, "Oh, Boy," This month the Oxford University Press publishes Obrdman's "Jerome Kern: His Life and Music," the first detailed biography of the man authoritative Stanley Green calss "the first detailed biography of the man authoritative Stanley Green calls "the recognized father of the modern musical theater."

While it took decades for Kern's rich style to develop, hi forte always seemed to be constantly renewing freshets of melody. While he was creatively ahead of what his audiences could assimilate, he worked within turn-of-the-century formats but was able, when audiences gained sophistication, to stretch from integrated stage scores to swing in Fred Astaire films.

Kern would come to recognize his successor in Richard Rodgers. And the closest to Kern now of musical show composers is the melodic Jerry Herman, whose fow unfortunately has been damned by troublesome books. But listen to recordings of "Dear World," and "Mack and Mabel" and "The Grand Tour" to hear Kern's latest echoes.

Suitable books were vital to Kern and if he didn't like a proffered libretto, he'd not compose for it. He insisted, Bordman tells us, that a successful work rested on the work of all, on compatability of each ingredient. sIt's striking that his most effective scores had such collaborators as P. G. Wodehouse, Guy Bolton, Oscar Hammerstein ii, Otto Harback and Dorothy Fields.

He shuddered, early on, at obvious song cues and tied each song carefully to the characters and incidents of play or film. Initially under the prevailing vogue for European operetta, Kern later developed a flavor so American that many assume "Ol' Man River" to be a folksong.

The "Showcase" revival of "Oh, Boy!" was presented by what Bordman and his associates, Ethel Watt and Berthe Schuchat, call the New Princess Theater Company, saluting the vanished house where Kern's earliest hits were produced. The four-week Off-Off-Broadway run was budgeted at $12,000, allowing performers $100 each for four weeks of rehearsals and four weeks of performances.

"Crazy, isn't it?" asks Bordman. "The original cost $17,000 to produce but on Broadway today that would be $800,000." He scorns revivals of old musicals that interpolate numbers not in the originals and positively loathes the use of mikes (fortunately unnecessary at the Smithsonian).

After taking a graduate degree in medieval studies at the University of Pennsylvania, Bordman had expected to run a family business. But when what he considered "impossible union conditions" arose, he simply sold out. Now on his Lancaster farm, Bordman, pursuing a hobby which became a passion, must be one of the world's most contented men.

His first venture, "American Musical Theater: A Chronicle," also published by Oxford, has been universally recognized as the most detailed and authoritative in its field. During the five years he spent compiling this remarkable volume, Bordman realized that the least documented of all American composers in Kern, who died in 1945 at the age of 60.

Unlike most of his contemporaries (including Irving Berlin, three years younger) Kern, born in 1885, came from a well-to-do Jewish family of German rather than Russian roots. Jerry saw his first musical on his tenth birthday and by the time he was a high school sophomore, was composing the Newark, N.J. school's senior play.

Father Henry planned a career for his son in a family-owned furniture store.Instructed to buy two pianos from a Bronx manufacturer, young Jerry unaccountably signed up to buy two hundred of them. "You can't imagine," he would chortle years later, "what it looks like for 200 pianos to come off moving-vans."

That effectively ended his merchandising career, but by the time he was 17 and a high school drop-out, he'd landed a job with music publisher Edward B. Marks. The next year he enrolled for courses at New York College for Music.

For would-be composers of 78 years ago, the world was complex too. One way to start was as a "song-plugger" playing piano in stores to hype sales of sheet music. He broadened his acquaintances.

In those days musical shows often hadnot one composer, but several, even many. For a decade or so, Kern would have a song in one show or another, his interpolations spreading to London, where he began a lifetime of working visits in 1903. Though programs would credit a single composer, like as not several more had contributed additional numbers. If one number clicked, the composer had likely chances for other spots. It's revealing that though the Frohmans used a good many Kern songs, they never gave him credits.

Bordman is inexhaustible, even exhausting, in his combing of old New York, London and provincial programs, feretting out long-forgotten early Kern songs. He has gone back through newspapers and magazine reviews to figure out plots and characters, to trace who sang what, when and why or whatever happened to a tune Kern might drop and pick up for use years later.

This is common custom for all composers, much as plays are evolved through various stages by their authors. A one-act Tennessee Williams often has grown into a full three acts. A disappointing long Arthur Miller play can evolve into a musical, as happened with "The Creation of the World and Other Business." The Greeks, Roman, Moliere and Shakespeare were constantly reworking material from others. Plagiarism suits arise against composers, who are generally acquitted.

The melody for "Smoke Gets in Your Eyes" was first written as a tap dance bit for "Show Boat" and subsequently dropped. Then it became a march for an NBC radio series in 1932 which never got on the air. Slowing the tempo for a "Roberta" ballad, Kern finally found a home for his haunting melody.

Reading Bordman, it's amusing to rediscover how downright wrong reviewers and critics have been as prophets over the years. They paid no attention at all to a song Helen Morgan sang atop a piano, "Bill." It originally was composed for, but then cut, from 1918's "Oh, Lady! Lady!!" Later it was turned down for Arilyn Miller to sing in "Sunny." Finally it got on stage in "Show Boat," whose other lyrics were by Hammerstein. But "Bill's" lyricist, Wodehouse, was carefully awarded program credit, a result of Kern's uncredited early years.

By the time Bordman got to his research, most of Kern's early associates had died so has had to dig hard all over America and England. The result is that the young Kern is a shadowy fellow glimpsed mostly through his comings and goings and the reflection of his music. Bordman has gone to such experts as Alfred Simon and Alec Wilder for critical anlyses of scores of songs. While many are hard to find on records or sheet music, the biographer's purpose is troutly served.

From those who knew him in his final 20 years, however, Bordman has re-created a wry, gently mocking man, addicted to practical jokes, puns and gambling.

There were unexpected sources too. Though they met only once, in 1929, when she was a musically sophisticated Philadelphia society girl, Kathleen Ritter and Kern developed "an endless correspondence," which lasted till his death, by which time she had long since become Baltimore's Mrs. Joseph Cooper.

Bordman carefully avoids fashionable probings about personal relationships. Kern fell in love with an English innkeeper's daughter in 1909, and within hours he hold her he wanted to marry her.It took him a year to get back from America to Eva Leale, but their marriage leasted the 35 years to his death.

Initially restrained in aiding the biographer, their daughter, Betty Miller from North Carolina, produced invaluable manuscripts and photographs. mThe result is the definitive work on Jerome Kern, the sort of fastidious record only the dogged author of "American Musical Theater" could compile.