Ink and water-colour technical drawing showing a longitudinal cross-sectional elevation of the first paddlesteamer built by the Scottish engineer and inventor, William Symington, C.E., with assistance from James Taylor and others, in 1787-88. The vessel depicted is an experimental steam-powered paddleboat built for Patrick Miller Esq., a prominent Edinburgh merchant and banker.
Late in 1787, Miller commissioned Symington to build a steam engine for the experimental vessel, based on his improved atmospheric condensing engine design, patented in June 1787. The drawing shows the vertical twin-cylinder single-acting engine that was fitted into one side of the double-hulled catamaran-style vessel. The steam boiler shown behind the engine was mounted in the opposite hull, while the two paddle-wheels were mounted in tandem in the gap between the hulls. The design incorporates a system of chains and ratchets proposed in Symington’s patent, to transfer the reciprocating motion of the piston rods to a forward rotary motion of the paddle-wheels.
On 14th October 1788, a public demonstration of the vessel operating under steam was made at the country estate of Patrick Miller on Dalswinton Loch, Dumfrieshire, witnessed by Mr Miller and a party of invited guests. It is believed to have been the first demonstration of a practical steam-powered vessel in Britain, and was sufficiently promising to encourage Miller to fund the construction of a second paddleboat and further trials on the Forth and Clyde Canal the following year.