By the King's letters patent : Royal filtering vessel for supplying ships with pure & wholesome water.

Leaflet advertising the 'Cygnet Filtering Vessel'. The Cygnet was a ship moored off Wapping docks, London. Includes a testimonial from J.W.B Leeson (lecturer on chemistry, assistant physician to St. Thomas's Hospital) to Mr. W. Raymond, dated 31st January 1842, as to the purity of water obtained. An illustration of a barge-like ship is at the top above a royal crest incorporating a lion and a unicorn.