Although the watermarks in An Island in the Moon have been the object of research by several scholars, thus far they have not been clearly described or, I believe, reproduced. Both Palmer Brown and Paul Miner made inquiries in the 1950s with the staff at the University of Cambridge’s Fitzwilliam Museum, where Blake’s manuscript is kept, and Miner speculated on the identity of the paper. In his 1977 Blake Books, G. E. Bentley, Jr., also noted the similarities between several Whatman watermarks and countermarks and those in Blake’s holograph. Before I describe these devices and compare them with other watermarks from the same period, a review of the basic facts about the paper in this manuscript seems in order.