The University of Wisconsin-Madison and the Wisconsin Historical Society announced Thursday that they are making nearly 500,000 historical books and documents available for a new search engine that aims to do with books what Google has done for Web sites.

Google is to create digital copies of the texts and make them available for search and download at www.books.google.com. In exchange, the university and the historical society are to get digital copies of their own.

“We’re thrilled to be working with them,” Google spokeswoman Megan Lamb said. “We think it’s going to add a tremendous amount of historical documents and materials to Google Book Search.”

With a combined collection of 7.2 million volumes, the university and the historical society are ranked 11th in North America, according to the Association of Research Libraries. They see Google Book Search as a way to preserve and expand access to their texts, said Edward Van Gemert, interim director of the UW-Madison library system.

But in striking the agreement with Google, the university and the historical society are entering a controversial online frontier.

Major publishing companies are suing Google over the new search engine. They said the company was breaking the law by reproducing and exchanging copyrighted texts that libraries handed over.