To speak precisely, she was begun in 1839, and launched in 1841, at Philadelphia. She was of 1692 tons burthen, and 225 feet long. She carried two ten-inch, and eight eight-inch guns, and a crew of 525 men. Her cost was $567,408. The cost of the iron-clad “Steven’s Battery,” as limited by Congress, was not to exceed that of the twin wooden steamers. Hence, its construction languished, while the _Mississippi_ and _Missouri_ were soon built. Perry, from the first, strenuously urged that the greatest care should be used, the best materials selected, and the most trustworthy contractors be chosen. “In the first ocean steamers to be put forth by the government, no cost should be spared to make them perfect in all respects.” As there was then no lack of harmony and union among the bureaus, there was no danger of constructing different parts of the ship on incompatible plans, with the consequent peril of failure of the whole. The various constructive departments wrought in unison. These two steam war vessels were built before naval architecture and the sea alike were robbed of their poetry. The _Missouri_ beside her machinery, carried 19,000 square feet of canvass, and the _Mississippi_ about as much, so that they looked beautiful to the eye as well as excelled in power. On her trip of March 5, starting at eight pounds pressure and rising to sixteen, the _Missouri_ made twelve and a half statute miles per hour. Her motion was quiet and graceful, the tremor slight, while at her bow, above the cutwater, rose a _boa_ of water five feet high. A trial at sea with her heavy spars was made on the 24th of March. In pointing out her merits and the defects, Perry emphasized the necessity of having in the persons, in charge of the equipment of war steamers, a combined knowledge of engineering and seamanship. In the men who presided over the machinery, this was noticeably lacking. Most engine-builders and engineers in 1841 had never been at sea; hence a knowledge of all the details necessary for safety and efficiency was not common. [Illustration: THE UNITED STATES STEAM FRIGATE MISSISSIPPI.] During the month of October, the twin vessels were made ready, and on the 9th of November, proceeded to Washington. On her return, the _Mississippi_ made the time from the Potomac Navy Yard to the Wallabout in fifty-one hours.