Originally Posted by bobvenem
The pdf files at archive.org are photographic pdfs, rather than text pdfs. That is, the files are graphic images of the pages; they cannot be searched like a text file can.
This makes them less useful then they could be, but the amount of time necessary to convert them to text would be prohibitive for their organization (the work is done by volunteers).
If you can get a copy of Adobe Acrobat (not Reader), you can add your own bookmarks to their volumes, which would at least make accessing chapters and passages a little easier.
Actually many of the PDF's are text PDFs. All the ones from Google are photographic PDFs