But there is no sentiment in progress; its demands are practical and imperative, and the great motive power, steam, was being crowded to the front even during this the greatest development in the era of sails. Advanced ideas could not be resisted, and steam was admitted as an auxiliary; but our development in naval construction still stood us in good stead, and enabled us to supply ships with auxiliary steam-power, which continued to be prominent for many years as standards to which others found it to their advantage to conform. Before the final abandonment in the navy of sailing-ships, pure and simple, an effort at a compromise was made by limiting steam to side-wheel vessels, and a number of fine ships were built in the forties which did good service, and were a credit to the country, answering as they did the demands of the time. The _Mississippi_, _Missouri_, _Susquehanna_, _Saranac_, and _Powhatan_ carried the flag to all parts of the world for many years, some of them enduring to bear their share in the late war, while the _Powhatan_ was borne on the list of vessels of the navy until within a few months. [Illustration: U. S. SIDE-WHEEL STEAMER “POWHATAN.”] This vessel was built at Norfolk, Virginia, in the year 1850. Her length was 250 feet, beam 45 feet, draught of water 19.6 feet. She had a displacement of 3980 tons, and attained a speed of 10.6 knots per hour with an indicated horse-power of 1172. The capacity of her coal-bunkers was 630 tons. Her battery consisted of sixteen 9-inch smooth-bore guns. She was built of seasoned live-oak, and though frequently under repairs, retained so much of the strength of her original construction that she escaped the sentence of condemnation until recently. The _Princeton_, of great fame, and the _San Jacinto_, were the only ships with screw-propellers that appeared in the period under consideration, the screw then being considered of such doubtful propriety as to need the test of tentative experiments. These ships have long since disappeared, but the screw remains, and side-wheels are mainly relegated to boats for inland waters. Confidence being established in the screw-propeller, construction on the principle of auxiliary steam-power was decided on, and ships of different classes were added to the navy in such numbers as the varied duties required.