Fortification

the art of increas: ing by engineering devices, the fighting _ of troops who occupy a position. he great improvements lately made in the construction of heavy guns have rendered it nece ary to rev is« the systems of fortification formerly in vogue. Iron and steel turrets are taking the place of masonry on low sites which are much exposed and where earth cannot be employed ad. vantageously. These turrets are re. volving cupolas, with spherical roofs: while in some instances the guns are mounted on disappearing carriages. In the United States the frontiers exposed to attack being very largely maritime the fortifications are principally bat: teries of heavy guns adapted to a contest with steel-plated ships. These are inclosed in the rear with.a land front, as protection against a land attack, but not made sufficiently strong to stand a long siege, it being taken for granted that reinforcements can quickly be provided to repel a_besieging force. It was formerly usual to mount guns in masonry casements built tier over tier, this method of building being common throughout the world. But this method has been dis earded in consequence of the modern development.in ships and guns. The system recommended by a board of military engineers, in 1886. proposed the use of steel turrets. armored casements, barbette batteries, mortar and floating batteries, and submarine mines; but so rapid has been the advance of military progre that the plan outlined by that board has been very largely modified in recent constructions, it having been found that, all things considered, earth and sand constitute the most effective defense. Iron-clad Forts.— For nearly an entire generation— ever since 1859 — the progre of fortification in Europe was in the direction of the use of some form of iron armor. In England the nece ity for using iron in fortifications was apparent just as soon as this material began to be used in ships,. 59. and in 1861 England entered upon the work of rebuilding her forts with iron. It was substantially completed in 1878, at a cost of $37,000,000, exon nine harbors, Within the ast few years have come the solid iron turrets, of enormous thickne , carrying two 80-ton guns each, which form part of the defenses of Dover, England.. While many of these forts, which were built while the contest between guns and armor was still in progre , can be pierced by the more recent guns, yet the number of large guns which they mount is far superior to the number that could be brought against them afloat, and in connection with torpedoes and ironclad ships they afford a secure defense.