Bell’s story was that these letters were left in Miller’s hands. Bell further states that the consideration of the absurdity of writing his opinion to other countries, and not putting it into practice himself, roused him to design a steamboat for which he made various models. The result was the _Comet_, built for him by John Wood and Co. She was 40 feet on the keel, 10¹⁄₂ feet beam, and about 25 tons burden. The vessel was inferior to Symington’s. The furnace was enclosed with brickwork and the fire was not wholly surrounded by water. The boiler was placed at one side of the vessel, and the funnel, bent so as to rise from the centre, also had to do duty as a mast. Bell had previously witnessed the experiments made in 1789 at Carron with Miller’s second boat, and when Symington’s experiments came to an end in 1803 he continued to investigate on his own account. He advertised that his vessel was for passengers only, and that he had “at much expense, fitted up a handsome vessel to ply upon the River Clyde, between Glasgow and Greenock, to sail by the power of wind, air, and steam.” The vessel was to go down to Helensburgh one day and return the next, thus making three trips each way in the week. Many of the sailing-boat owners regarded the _Comet_ with undisguised hatred, and its invention as a device of the evil one. Thus, one Dougal Jamson, a Clyde skipper, whenever the steamboat passed his slow-going sloop,[30] invariably piped all hands--a man and a boy--and bade them “Kneel down and thank God that ye sail wi’ the A’michty’s ain win’, an’ no’ wi’ the deevil’s sunfire an’ brimstane, like that spluttery thing there.” [30] _The Steamship_, January 1883. [Illustration: MODEL OF THE “CHARLOTTE DUNDAS.”] The _Comet’s_ engine, which was built by John Robertson, was of four nominal horse-power with a single upright cylinder of 12¹⁄₂ inches diameter and 16 inches stroke, and drove a pair of half side-levers by means of two rods. A connecting-rod from the levers worked the crank shaft, which carried a heavy fly-wheel. The slide valve was driven by an eccentric on the main shaft through a rocking shaft, while the condenser was placed between the side-levers, which drove the vertical air-pump. Originally the engine was fitted with a smaller cylinder, but after being used for some months this was replaced by the one described. Steam was supplied by an internal flue boiler, built by David Napier. The vessel was originally propelled by two paddle-wheels on each side, driven by spur gear, with the paddles on detached arms, but this arrangement giving trouble, complete wheels were substituted, and subsequently, after the vessel had been lengthened about 20 feet, the number of wheels was reduced to two.[31] [31] “The Clyde Passenger Steamers,” by Captain Williamson, and Catalogue of the Victoria and Albert Museum, London.