Army Corps

Two or more divisions. A corps is complete in itself as an army, having infantry for its main body, and such proportions of the other arms of the service as to make it It is commanded by a major-general. many, France and Ru ia. It consists of iron with steel face. Ellis (Brown) system consisted of a wrought-iron foundation (back) plate and wrought-steel (face) plate united by liquid steel; subsequently rolled to the required thickne . Tresidder substituted 2 per cent nickel steel for the face plate. Wilson (Cammell) system consisted of thin iron plates rolled together to form foundation (back) plate, which after thorough scaling receives liquid steel to form the face plate; the whole is then rolled to the required thickne . Sandwich armor was composed of alternate layers of metal and wood; not now employed for ships. The British ship Inflexible has this 26 in. thick. The severest requirements are those of the U.S., and comprise, in addition to a personal official inspection of all operations, chemical analysis, physical tests for elongation, tensile-strength and uniformity, and a ballistic test of one or more plates selected from a lot the weight of which is determined by the naval inspector. The ballistic test consists of firing a certain number of projectiles against the selected plate at determined energies for cracking and perforation.