The next steamers built on Western waters were probably the Comet and the Vesuvius, both of which were in service some time. The Comet was finally laid aside, and the engine used to drive a mill, and the Vesuvius was destroyed by the explosion of her boilers. As early as 1813 there were two shops at Pittsburgh building steam-engines. Steamboat-building now became an important and lucrative business in the West; and it is stated that as early as 1840 there were a thousand steamers on the Mississippi and its tributaries. In the Washington, built at Wheeling, Va., in 1816, under the direction of Captain Henry M. Shreve, the boilers, which had previously been placed in the hold, were carried on the main-deck, and a "hurricane-deck" was built over them. Shreve substituted two horizontal direct-acting engines for the single upright engine used by Fulton, drove them by high-pressure steam without condensation, and attached them, one on each side the boat, to cranks placed at right angles. He adopted a cam cut-off expanding the steam considerably, and the flue-boiler of Evans. At that time the voyage from New Orleans to Louisville occupied three weeks, and Shreve was made the subject of many witticisms when he predicted that the time would ultimately be shortened to ten days. It is now made in four days. The Washington was seized at New Orleans, in 1817, by order of Livingston, who claimed that his rights included the monopoly of the navigation of the Mississippi and its tributaries. The courts decided adversely on this claim, and the release of the Washington was the act which removed every obstacle to the introduction of steam-navigation throughout the United States. The first steamer on the Great Lakes was the Ontario, built in 1816, at Sackett's Harbor. Fifteen years later, Western steamboats had taken the peculiar form which has since usually distinguished them.