Scale 1:96. Drawing showing the barque-rig sail plan, and dimensions of masts and spars for four wooden three-masted paddle steamers of the same class for Cunard (The British & North American Royal Mail Steam Packet Company, Glasgow). These were Britannia (1840), built by Robert Duncan, Greenock; Acadia (1840), built by John Wood & Co, Port Glasgow; Caledonia (1840), built by Charles Wood, Dumbarton; and Columbia (1840), built by Robert Steele & Co, Greenock. The plan also includes the sail plan for Centaur (unknown date), a three-masted barque-rigged sailing (or paddle) vessel. The identity of Centaur is unknown. The 1841 Lloyd's Register of Shipping lists one - a schooner-rigged ship built by Wood & Co in 1839.

The plan includes the Admiralty Letter Book Number S4197 indicating that these were drawn for, and sent to, the Admiralty. William Blessley was a draughtsman at Portsmouth Dockyard in 1836.