Scale: unknown. A contemporary full hull model of HMS 'Dwarf' (1840), a single-screw sloop. The model is decked and partially equipped. Plaque inscribed ‘The first screw vessel in the British Navy "Mermaid" afterwards renamed the "Dwarf" built in 1840, purchased from C & J Rennie by the British Admiralty according to Sir George Cockburns advice on the condition she should steam 12 miles per hour (17th March 1842) Tried 15 May 1843 Mean speed of 6 runs 12.142 miles’.

Measuring 130 feet in length by 16 feet in the beam and a tonnage of 164 burden, this iron-screw vessel was eventually sold for breaking in 1853. The model is said to have been made by the shipyard of C. & J. Rennie.