There are many years of the Universalist Register, the denominational directory, on either side of the turn of the twentieth century available from Google Books. But there’s a catch. The most useful part (I think) is the set of charts identifying the location of parishes and churches, their membership, minister, clerk and how often they meet for worship. These are printed at ninety degrees to the running text, and the Google’s scanning treated them like images, and lifted them out of the text. Not helpful.
I found a single issue of the Register — the 1912 edition — scanned by and from the Library of Congress. A touch of irony: the charts are printed right way up, so it wouldn’t have mattered.
Lots of fun things therein.