British Guiana - 1853-1859 1d ship issue, negative glass support cliché in black, image reversed, with a manuscript production notation along the right side, indicating an exposure time of 2 minutes and 30 seconds, information necessary for refining the quality of the impression through different exposure times. No mention is found in the literature dedicated to Sperati or on Richard Frajola’s online database of British Guiana, which makes this lot of the highest importance considering the significance of this territory in classic philately. About 15 items in existence. (Image)