The civil war in 1861 brought with it a novel and striking form of war vessel known as the “Monitor.”[4] It was built from plans of Capt. Ericsson, an engineer of the ripest experience, skill, and attainments, who had then come to make his home in the United States. He undertook to construct for the Navy Department of the United States some form of iron clad steam batteries of light draft, suitable to navigate the rivers and harbors of the Confederate States. The “Monitor” was the result. The salient features, shown in vertical cross section in Fig. 117, are a low deck projecting but a few inches above the water line, so as to present as little target as possible to the enemy, and a revolving and heavily armored turret containing the battery of guns. In 1862 the Confederate forces had reconstructed a steam vessel with a chicken-coop-shaped covering of armor, that proved a formidable engine of war, which was practically invulnerable to the attacks of ordinary war vessels, and was doing great damage to the Union vessels. In the spring of 1862 the “Monitor” met the “Merrimac” in engagement in Hampton Roads, and established the great value of the turret monitor. [4] The revolving turret was invented and patented by Theodore R. Timby, No. 35,846, July 8, 1862, and No. 36,593, September 30, 1862. [Illustration: FIG. 117.--CROSS SECTION OF “MONITOR.”] Vessels of the “Monitor” type still form useful parts of the United States Navy, in which the “Monterey” and “Monadnock” are its most representative types. The “Monadnock,” which is a double-turret coast defence monitor, is shown in Fig. 118. Although regarded by some as unseaworthy on account of the low seaboard and small buoyancy, the monitor has cleared itself of such suspicion, for in the recent war with Spain both the “Monadnock” and “Monterey” sailed across the Pacific Ocean by way of Honolulu to Manila, a distance of 7,000 miles, and joined the fleet of Admiral Dewey without mishap or delay. [Illustration: FIG. 118.--MONITOR “MONADNOCK.”]