Inscribed by the artist 'PROBUS', lower right. These sketches are of the 179-ton merchant brigantine 'Thirza' (official number 51924) built on Prince Edward Island (in the St Lawrence estuary, Canada) in 1865. For nearly all of her life she was registered at Faversham, Kent, but on 30 August 1915, when owned by the Whitstable Shipping Co. Ltd, she was requisitioned by the Admiralty for conversion and service as a Q-ship (submarine decoy ship), renamed 'Probus' and armed with two 12-pounder and two 6-pounder guns. As such she operated under the names 'Thirza', 'Elixir', 'Q30' and 'Ready'. She returned to commercial service on 11 November 1918 and reverted to her original name of 'Thirza', being then owned by James Livingstone & Sons Ltd. She disappears from registers in 1920,when she was probably broken up. The top right sketch is of one of her 6-pounder guns and that at bottom left one of her 12-pounders. The other three are a deck scene looking aft, under sail, and a port-broadside and port-bow view of the ship in calm conditions.