The treatise may be read with one of three computer programs. The most versatile is the full version of Adobe Acrobat. This program may be purchased from http://www.adobe.com.
The other two programs are available free via the links below. I would choose first the eBook reader because it lets you annotate.
If you already have one of these programs and experience problems reading the treatise, check the version. The treatise needs version 4 or higher of Acrobat or version 2 of the eBook reader.