THE LIBRARY OF CONGRESS' Prints and Photographs Division is 12 million images strong and growing. "New For You," an exhibit in the Madison Building, showcases 290 new acquisitions or discoveries that have been catalogued within the past five years.

Yes, discoveries. It's understandable that the largest library in the world could overlook a few things. For example, William Henry Jackson's photographs of the American west. Broad vistas from the turn of the century, 700 of his glass-plate negatives were recovered from storage last year. The 22 unmarked wooden crates that contained them had been unopened since the State Historical Society of Colorado donated them to the library in 1949. The edges of the plates do look a little the worse for wear.

Within the Red Cross Collection, researchers have now identified photographer Lewis Hine's work. He was known for his photographic survey of American child labor, but not for his part in the American Red Cross Balkan survey during World War I.

And then there's the 1816 wallpaper, among the earliest produced in this country, that turned up when Prints and Photographs was moving to the Madison building in 1982.

But most of this treasure trove has been recently purchased, rather than found.

In developing its Master Photographs collection, the Library has been choosing contemporary photographers, to join the files with Steiglitz and Steichen: Bruce Davidson, Arnold Newman, Lisette Model, Rosalind Solomon. Documentary photographs include the recently catalogued work of Toni Frissell -- fashion shots of models draped on monuments and unpublished photos of the only all-black squadron of World War II pilots.

The photos are immediate, accessible. But there are also delightful posters here, recent buys, from the earliest Flying Wallendas poster to a David Hockney design. And fine prints -- an Italian chiaroscuro woodcut, late 16th century, and an abstract color woodcut monotype by Sam Francis, late 20th century.

From the Architecture, Design and Engineering Collections, you will also find Maya Lin's original design for the Vietnam Veterans' Memorial. She was an architecture student at Yale when her controversial design won the competition, and here is her moving hand-written description, misspellings and all.

But no need to catalogue them further. That's already been done.

NEW FOR YOU -- In the Madison Building at the Library of Congress through October.