In 1812 he and John Robertson built the steam-boat the "PS Comet", of 30 tons burthen, with an engine of three horsepower. The Comet, named after a great comet which had been visible for several months in 1811–12, was built by Messrs John Wood and Co., at Port Glasgow which lies 3 miles to the east of Greenock, as adjacent towns on the south bank of the River Clyde as it widens into the Firth of Clyde. The "Comet" made a delivery voyage from Port Glasgow 21 miles upriver to the Broomielaw, Glasgow, then sailed from Glasgow the 24 miles down to Greenock, making five miles an hour against a head-wind. "(some sources give a date of 18 January 1812 for a trial trip, McCrorie gives 6 August 1812 for the delivery, with the historic trip a day or so later.)" In August Bell advertised a passenger service on the "Comet" between Glasgow, Greenock and Helensburgh three times a week, returning on alternate days, "to ply upon the River Clyde from Glasgow, to sail by the power of air, wind, and steam."