 In the 1830s, navies experimented with large paddle steamers equipped with large guns mounted on one deck, which were termed "paddle frigates".From the mid-1840s on, frigates which more closely resembled the traditional sailing frigate were built with steam engines and screw propellers.These "screw frigates", built first of wood and later of iron, continued to perform the traditional role of the frigate until late in the 19th century.