PROVIDENCE, R.I. (AP) _ Brown University has asked police to find out how a turn-of-the-century chandelier that disappeared from the school sometime in the late 1970s has reappeared in the newly renovated Providence Public Library.

The 175-pound chandelier, whose value is estimated at $15,000 to $20,000, is the centerpiece of the library's periodicals atrium, which was opened to the public with much fanfare two weeks ago.

After the ceremony, Brown officials realized the chandelier was identical to one that had hung in Alumnae Hall from 1927 until it was taken down during restoration work about 10 years ago, said university spokesman Robert Reichley.

''Someone took a photo from our archives and compared it,'' Reichley said. ''There doesn't seem to be any doubt whether it's one and the same.''

Joseph Enright, a Providence dealer in light fixtures, told The Providence Journal in a story published Monday that he bought the fixture in 1985 from a Brown maintenance man who said he would take the chandelier to the junkyard if Enright did not want it.

Enright later sold the chandelier to Arthur Groger, a Newport antiques dealer, who rented it to Trinity Repertory Theater in Providence for a production of ''All the King's Men.'' The library purchased the chandelier from Groger last year after a staffer saw it at the theater, the newspaper said.

John Kuprevich, Brown's director of police and security, said his department has asked city police to help investigate. ''It is our belief that it was not authorized to be disposed of in any way, shape or form,'' he said.

Reichley and Howard E. Walker, chairman of the library's board of directors, said it was too early to tell whether Brown would attempt to recover the chandelier.

''We're working cooperatively and amicably in trying to solve this issue,'' Reichley said.

''I think it looks splendid. We certainly think it's an ideal fixture for our location,'' Walker said.