WASHINGTON (AP) _ To the relief of scholars, the Library of Congress' Main Reading Room reopens June 3, restored to its 19th century stateliness but with some of the latest 20th-century apparatus under its vast dome.

The circular reading room, the starting point for gaining access to 15 million books, has been closed since September, 1986, as part of a seven-year, $81.5 million renovation of two of the library's three main buildings. The room has often been called one of the most handsome in America.

The library was originally built in 1897, finished in 20 months for $6,032,000. The builder returned an unspent $150,000 to Congress.

Researchers - the library is open to all over high-school age and is busiest during the spring and fall term paper seasons - have been forced to use the cramped Social Sciences Research Room.

The library's often-photographed features - a soaring 160-foot arching dome, encircled by 11-foot statues and paintings and quotations - are back. So are the 1940s reading lamps and the original terra cotta color of the walls, rediscovered by scraping away years of paint.

But gone is the card catalog and its 22,265 drawers of 3-by-5 cards. It has been replaced by a computer.

Visitors can sit at 60 terminals and by touching questions on the screen get the same information about books the card catalog used to provide. The push of a button prints it out and the visitor can then go to the chief reference desk to ask a librarian for his books.

Computer-unfriendly users can still rely on the card catalog, in an adjacent room, but it is out of date. No new cards have been added since 1980, said Suzanne Thorin, chief of the general reading rooms division, during a press tour last week.

In the card catalog's space, 44 reader desks were added, allowing the reading room to accommodate 226 researchers. Wiring now allows them to plug in laptop computers. Four miles of data cable was installed so that researchers ultimately may be able to hook into the library's own computer system.

Ms. Thorin said researchers will be separated - those who take notes on computers seated on one side, those who can't abide the click-click-click of the keys on the other.

In the renovation, the room was carpeted for the first time, a fire sprinkler system was added, windows that had been covered over were restored and balcony alcoves were glassed in to become carrels for visiting scholars.