Washington ? The lifework of the late legendary American folklorist Alan Lomax has been acquired by the American Folklife Center in the Library of Congress.

“I think it’s the jewel in the crown of the collections here,” says Peggy A. Bulger, director of the folklife center, “because it spans 70 years. It’s almost an entire century of documentation by one person who was an incredible collector and who had an ear for excellence.”

The Lomax collection, she says, offers a vast sampler of “the very best music, dance and stories from 1930s to present day.” The library expects scholars to benefit from it for eons to come.

The purchase of the research material was made possible by the gift of an anonymous donor; the library was close-lipped about the actual cost. To hear folklorists talk, however, whatever the library paid is a bargain: The collection is considered to be priceless.

Lomax, who took his first folkloric steps at the library in the 1930s, recorded and collected indigenous music, dances and stories from this country and others. He was especially fascinated by the idea that a culture’s music or way of dancing speaks to its very core.

He marveled at the relationship of one people’s music to another’s, and he tried to break down musical expression into what he called “cantometrics,” a quantifiable set of attributes such as tones, beats, phrasings. He conducted similar deconstructions of dance and storytelling.

When he was felled by a stroke in 1996, he was attempting to assemble a worldwide multimedia database that he called the Global Jukebox. He died in 2002.

Some academics and melody lovers saw madness in Lomax’s obsessive methodology, but no one questioned the ambition and grandeur of his quest. “It’s a beautiful idea,” says the collection’s curator, Todd Harvey.

He’s the guy who will be dealing with more than 5,000 hours of sound recordings, 400,000 feet of movie film and 2,450 videotapes. The library is also receiving 2,000 scholarly books and journals from Lomax’s personal shelves, scads of photographs, letters, manuscripts, lectures and ephemera of all sorts.

With such a multimedia trove, the library could well become the cosmic carousel inside Lomax’s Global Jukebox.

Harvey is only beginning to appreciate the mother lode. He opens one of the boxes, labeled 27-9, and pulls out a copy of “A Treasury of New England Folklore” by B.A. Botkin. The book was inscribed to Lomax “in the vanguard and in the traditions.” Botkin, Harvey says, succeeded Lomax as the library’s primary folklorist. Beside it he finds a rare first-edition history book.

The relationship between Lomax and the library goes way back. From a very early age, Alan Lomax — sometimes working with his folklorist father, John Lomax — collected examples of music and folkways from around the world. Father and son made their first recordings for the library in the summer of 1933. Alan was 18. The two traveled around their native Texas, recording ballads, reels, work chants, blues and hymns. John Lomax became an honorary consultant to the library’s archive of the American folk song. Alan was named the archive’s assistant in 1937.

While working for the library, Alan Lomax became the first musicologist to record the uniquely American music of Huddie “Leadbelly” Ledbetter and McKinley “Muddy Waters” Morganfield.

He sat down with jazzman Ferdinand “Jelly Roll” Morton at the library’s state-of-the-art recording studio in 1938 and taped eight hours of Morton singing, playing and reminiscing. He cajoled folksinger Woody Guthrie into sitting still for four hours of singing and playing in 1940. Lomax was at the library for 10 years before lighting out on his own.

The library has always owned the work that Lomax did while working there. Now it possesses his whole kit-and-kaboodle.