British engineer who developed (1801) a successful steam-driven paddle wheel and used it the following year to propel one of the first practical steamboats, the Charlotte Dundas.

Although Symington was educated for the ministry at Glasgow and Edinburgh, his inclinations led him to become a civil engineer. His working model of a steam-driven road carriage generated much enthusiasm in 1786, and within a few years he had patented several improved steam engines. His use of chains and ratchet wheels to provide rotary motion allowed far more economical operation than Watt's design. His first use of steam for marine purposes in 1787 was followed by larger experiments. In 1789 a boat propelled by an engine of his design achieved a speed of 7 mph.

In 1801 he patented a new engine utilizing a connecting rod and crank, a system that proved superior for paddle-wheel operation. This engine was used in 1802 to propel the Charlotte Dundas on the Forth and Clyde Canal, thus launching the first steamboat fitted for practical operations. Cautious managers caused the project to be abandoned in 1803.