The Harvard Library will deposit about 200,000 public domain volumes in HathiTrust.
Here's an excerpt from the announcement:
The Harvard Library will deposit approximately 200,000 public domain volumes in HathiTrust, a shared digital repository for published materials. This follows Harvard's first deposit of approximately 53,000 volumes in HathiTrust in 2011.
"The Harvard Library is committed to collaboration and easing access to its materials. Partnerships like this create significant opportunities for research libraries to lead during a period of rapid changes in higher education and scholarship in the digital age, and for researchers to benefit from their initiative" said Mary Lee Kennedy, Harvard's senior associate provost for the Library.