Besides the Gutenberg Bible and a priceless collection of musical instruments by Stradivari, the Library of Congress owns Abraham Lincoln's spectacles, slightly damaged but held together with a piece of string, and a $5 Confederate banknote the Great Emancipator had in his pocket on the night he was killed.

The contents of Lincoln's pockets were found by Librarian of Congress Daniel Boorstin in a small, locked closet originally used to rare books. "Boorstin explains, and there were the Lincoln memorabilia.

All these items-among many more-are examined in loving detail in a 90-minute special, "The Library of Congress: A portrait of an American Institution," which will be telecast at 9 tonight on WETA-TV, Channel 26.

Narrated by Sir Huw Wheldon, the program makdes a valiant effort to encompass the contents and activities of the library. Senator Barry Goldwater is shown seeking information on the SALT agfreements and on the feeding habits of bald eagles. Old films demonstrate special effects at the turn of the century. The Juilliard Quartet is seen in one of its regular concerts. Boorstin discusses the conflicting demands of scholarship and congressional information.

Viewers learn that besides presidential papers, the library has those of Sigmund Freud and Groucho Marx, that it receives 7,000 new books each day and subscribes to 117,000 periodicals-only a part of the information it stores. The most maddening aspect of the library-knowing that material is there somewhere and wondering how to get it-is discussed briefly.

The domentary is a varied and lively as the library itself, but it leaves a viewer with the feeling that 90 minutes are not really enough.