Condensation from a malfunctioning climate control system damaged several hundred rare books in Harvard Law School's Langdell Library Treasure Room yesterday morning, library officials said.

Assistant Librarian for Special Collections David R. Warrington said approximately 500 books were affected by steam pouring out onto the top shelf of the third story of bookshelves in one of the Law School's rare book collections. He said that while almost 200 books may be permanently water stained, none were destroyed.

The Treasure Room, built in 1948, houses more than 1000 of the Law Library's rarest books in three stories of stacks, including a number of European law books printed before 1601. Warrington said most of the damaged books date to the 16th and 17th centuries.

A faulty valve in the library's climate control system may have caused the problem, said Warrington. The steam set off Langdell Hall's fire alarm at 11:15 a.m. yesterday.

Preservation Librarian Willis C. Meredith said that "for some unknown reason, the system that supposedly controls the temperature and humidity started to pump steam into the stacks."

Library officials said the malfunction was particularly unexpected because the climate control system in the stacks--which monitors humidity--had been shut down Tuesday so that workers could remove asbestos from the third-floor stacks this week.

"I guess for some reason something was still on, and it was getting the messagethat we needed more humidity," said Mary Person,Treasure Room supervisor said.

Warrington said the planned asbestos removalhad nothing to do with the malfunction.

According to Person, librarians reacted quicklyto the disaster, forming a "bucket brigade" tomove books from the top stacks to tables in theLangdell Reading Room. They spent the afternoon"interleaving" the books with paper towels andmoving them to a climate-controlled room to dryout, Warrington said.

"It was kind of a shock. My first reaction wasthat all of a sudden I wanted to cry," Personsaid.

Meredith said that because all the climatesystems in the stacks have been shut down, heatand humidity may endanger the remaining books inthe Treasure Room.

"We are fighting a battle to control the heatand humidity and to keep air circulating," saidMeredith, adding that other portions of theTreasure Room collection may still have to bemoved.

Officials said that library service will not beaffected by the incident. Building Operations willcontinue to look into the malfunction of theclimate system, and Warrington said that bookswill not be returned to the Treasure Room stacksfor several weeks.

Baiba K. Ozols, a Law Library cataloguer, said,"I have seen other disasters but never to thiscrucial an area." Warrington said that"unfortunately these things happen to thelibraries occasionally, but not often to the rarebooks collection.