An area with links to facsimiles of psalmody and gallery music books. Some may be downloaded free of charge. Others cost the same as it would to photocopy them in a physical library.
Note that the facsimiles are reasonably high-resolution pdf files. As a result, each file is several megabytes in size -- something to consider if you are using a dial-up Internet connection.
The Whole Book of Psalms, Collected in English Metre, By Thomas Sternhold, John Hopkins, and Others ... London: Printed by Susanna Collins, for the Company of Stationers MDCCXX  (6.3 MB) FREE
Jonathan Gibbons His Book (Castor 1786-88) (several files between 0.5 and 1.5 MB) FREE