The advantage of steam navigation for channel service was at once recognised. A Parliamentary return issued in 1815 showed that for the space of nine days in the previous year only one mail packet could sail between Holyhead and Dublin owing to adverse winds, and even then the average passage was twenty-four hours. Lord Kelvin, in his memorable Address as Chancellor of the University of Glasgow, in 1905, recalled the fact that early in the century his father often took three or four days to cross from Belfast to Greenock in a smack, as she was frequently becalmed. With favourable winds, rapid passages were made, a revenue cutter occasionally doing the Belfast and Greenock run in ten hours. The Greenock and Belfast route was among the first around the coast to come under the influence of the mechanical system of propulsion. The _Rob Roy_, which was the outcome, so far as form of hull was concerned, of probably the first model experiments ever made--undertaken by David Napier in the Canal at Camlachie[22]--was in 1818 the pioneer in the Glasgow and Belfast steam service, and later in the Dover and Calais steam service. There followed in 1819 three notable vessels from Scotts' Works: the _Waterloo_,[23] the _Robert Bruce_, and the _Sir William Wallace_. The particulars and performances of these vessels, taken from contemporary records, principally the "Greenock Advertiser," which faithfully reported each incident in the development of the steamship, are especially interesting as illustrative of early work. The _Waterloo_, which, as we have already said, was the largest steamer of her year (1819), had a beam equal to one-fifth of her length, the measurement between perpendiculars being 98 ft. 8 in. In addition to a large number of passengers, she carried under ordinary conditions a cargo of 100 tons, on a draught of 8 ft. 6 in. against 7 ft. 3 in. without cargo. Three months were required, between the launch of the ship and her trials, for the fitting on board of engines each of 30 nominal horse-power, which gave her a speed of between 8 and 9 miles per hour. Sails, however, were still carried to assist in driving the ship, and this vessel was of schooner rig. She inaugurated the steam service between Belfast and Liverpool.