The naval machine consists obviously of two parts, the personnel and the material; these two parts being independent, and yet mutually dependent, like the parts of any other organism.  Obviously, the parts are mutually dependent not only in the quantitative sense that the more numerous the material parts the more numerous must be the personnel to operate them, but also in the qualitative sense that the various kinds of material determine the various kinds of personnel that must be provided to operate them with success.  Gunners are needed to handle guns, and engineers to handle engines.

In this respect, personnel follows material.  In the galley days only two kinds of personnel were needed—­sailors to handle the galleys (most of these being men merely to pull on oars)—­and soldiers to fight, when the galleys got alongside of the enemy.  Ship organization remained in a condition of great simplicity until our Civil War; for the main effort was to handle the ships by means of their sails, the handling of the simple battery being a very easy matter.  Every ship was much like every other ship, except in size; and in every ship the organization was simple and based mostly on the necessities of handling the ship by sails.

The first important change from this condition followed the departure of the Confederate ironclad Virginia (Merrimac) carrying 10 guns and 300 men from the Norfolk Navy Yard on the 8th of March, 1862, and her sinking hardly two hours afterward the Union sloop of war Cumberland, carrying 24 guns and 376 men; and then destroying by fire the Union frigate Congress, carrying 50 guns and 434 men.  The second step was taken on the following day, when the Union Monitor, 2 guns and 49 men, defeated the Merrimac.  These two actions on two successive days are the most memorable naval actions in history from the standpoint of naval construction and naval ordnance, and perhaps of naval strategy; because they instituted a new era—­the era of mechanism in naval war.

The next step was the successful attack by the Confederate “fish-torpedo boat” David, on the Union ironclad Housatonic in Charleston harbor on February 17, 1864; and the next was the sinking of the Confederate ironclad Albemarle by a spar torpedo carried on a little steam-launch commanded by Lieutenant W. B. Cushing, U. S. N., on October 27, 1864.

These four epochal events in our Civil War demonstrated the possibilities of mechanism in naval warfare, and led the way to the use of the highly specialized and scientific instruments that have played so important a part in the present war.  During the half-century that has intervened since the Monitor and Merrimac ushered in the modern era, since the five brave crews of the David lost their lives, and since Cushing made his amazing victory, a contest between the sailor and the scientist has been going on, as to which shall