As most people will know, while a large number of the scans on the site have been done by me or various friends, probably the majority have just been found by trawling various sites online.  I thought it might be useful to maintain a list of the sites that are used, and if anyone has more please add them in a reply. I find new scans appear frequently, and the best way is often to search by author, or publisher. If you do come accross anything relevant, please add it to the website, using the 'Add Scan' link on the Bookshelf page, or emailing to me. Thanks.

• Google Books - www.google.com/books - items that have a front cover other than the generic brown one, but can't be downloaded, often can be using a US Proxy.
• Internet Archive - https://archive.org/
• Hathitrust - https://www.hathitrust.org/ - probably the largest collection; it is slightly tricky to download items as you need a separate program, the Hathi Download Helper - https://sourceforge.net/projects/hathidownloadhelper/ 
• University of Oxford Library - http://solo.bodleian.ox.ac.uk/primo_library/libweb/action/search.do

Some publishers that can prove userful to search for; James Nisbet, Pickering & Inglis, Marshall Morgan Scott, Loizeaux ... as well as the more common Brethren ones, such as Morrish, Broom, Rouse, etc.