Google apparently can't be bothered to interpret those copyright laws at all; they seem only really to care about the American 'market'. Farquhar is withheld from users in the country where the book was written and published, and where it is just as much out of copyright as it is in the USA.

However, the same book (actually, it even appears to be a copy of the same file) is available via the Internet Archive: http://www.archive.org/details/popularsongssco00grahgoog. Increasingly, books withheld by Google from non-American users are being made available at the Archive. The same user-name recurs rather a lot, so I suspect some 'Robin Hood' activity there.

The Archive is, in terms of open access, a superior resource; but it doesn't have a full-text search, so Google's main use is in locating things in digitized texts rather than accessing them. A link to the Archive, unlike a link to Google Books, is a link that is sure to be available to all.