There are several ways to search HathiTrust content.
After logging in at HathiTrust as a member of Texas Christian University, a link on the left of full view volumes allows you to download the entire volume as a PDF file. Downloading is for the entire volume and cannot be configured for single chapters or page ranges.
Without logging in, downloading (and subsequent printing) is limited to one page at a time in PDF for full view volumes (titles in the public domain and those with Creative Commons licenses).
Find out more at Help - Downloading.