Miller was born in Glasgow, the third son of William Miller of Glenlee, and his wife, Janet Hamilton. After attending the University of Glasgow, he decided to take up banking as his trade, since the Scottish economy was growing. By November 1760 Miller became partners with William Ramsay of Barnton, merchants and bankers, in Edinburgh. In 1767 he was elected to the court of the Bank of Scotland where he implemented a number of reforms, particularly the introduction of note exchange, whereby the bank agreed to accept notes of its competitors. Thanks to his improvements, the bank successfully endured a banking crisis in 1772. In his final years he served as Deputy Governor of the Bank of Scotland, being succeeded by Adam Rolland of Gask FRSE upon his death.
Invention and naval pursuits
While looking after shipping interests overseas, Miller experienced firsthand the dangers of piracy on his ocean voyages. These brushes with privateers combined with his time on the ocean sparked a lifelong interest in ordnance and naval architecture.
Warship
He attempted to interest various European navies in his design for a super warship, but only Sweden showed any notable interest; their great naval architectChapman called it the "English sea-spook". The Swedish kingGustav III, as thanks for the actual vessel, Experiment of Leith, that Miller sent him, despatched Miller seeds of the swede in a magnificent snuff-box, featuring marine illustrations, now in the collection of the Victoria & Albert Museum, London.
Pleasure boats
Miller was particularly interested in multiple-hulled pleasure boats propelled by cranked paddle wheels placed between the hulls. On seeing a steam-carriage model made by the engineer William Symington, he got Symington to build his patented steam engine with its drive into a twin-hulled pleasure boat. This was successfully tried out on Dalswinton Loch near Miller's house on 14 October 1788. The next year a larger engine was fitted to a long twin-hull paddle boat and tried on the Forth and Clyde Canal. After initial problems of paddle wheels breaking up on 2 December, the vessel travelled some distance along the canal on 26 December and 27 December 1789. Miller abandoned the project due to the rising expenses of the venture.
