FOBTIFICATION 178 FORTRESS up out of the ditch in front, having the ramparts and embrasures riveted with sods of turf, fascines, gabions, and sand- bags, the terre-plein for the support of the guns and their carriages being made of pieces of thick timber strongly bolted together. The great improvements lately made in the construction of heavy guns have rendered it necessary to revise the sys- tems 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 advantageously. These turrets are revolving' cupolas, with spherical roofs; while in some instances the guns are mounted on disappearing carriages. In the United States the frontiers ex- posed to attack being very largely mari- time, the fortifications are principally batteries of heavy guns adapted to a contest with steel-plated ships. It was formerly usual to mount guns in ma- sonry casements built tier over tier, but this method has been discarded in con- sequence of the modern developments in ships and guns. It was demonstrated during the World War when the Ger- mans smashed the Belgian forts that earth and sand constitute the most effec- tive defense. Stone, concrete and steel cannot withstand modern siegeguns. Iron-clad Forts. Since 1859 the prog- ress of fortification in Europe was in the direction of the use of some form of iron ai'mor. In England the necessity for using iron in fortifications was ap- parent just as soon as this material be- gan to be used in ships, and in 1861 England entered upon the work of re- building her forts with iron. It was substantially completed in 1878, at a cost of $37,000,000, expended on nine harbors. Within comparatively recent times have come the solid iron turrets, of enormous thickness, 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 ar- mor was still in progress, 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 con- nection with torpedoes and ironclad ships they afford a secure defense. On the Continent the problem was not taken up till guns had reached a greater devel- opment, and then it was solved generally in the direction of using iron alone, in the form of turrets or domes. Some were of wrought iron, some of steel, and some of cast iron. The latter were the Gruson cupolas, of which many were constructed in various harbors of Ger- many, Austria, Belgium, Holland, and Italy. See Fort. FORT LEE, a borough of New Jersey, in Bergen co. It is connected by ferry with New York City. Several important moving picture studios are located here. It has the Institute of the Holy Angels. During the Revolutionary War one of the forts defending the Hudson was situ- ated here. Pop. (1910) 4,474; (1920) 5,761. FORT MADISON, a city of Iowa, the county-seat of Lee co. It is on the Mis- souri river, and on the Atchison, Topeka, and Santa Fe, and the Chicago, Burling- ton and Quincy railroads. Its industries include pork packing, railroad shops, grain elevators, cement works, flour and saw mills, farm-implement works, button works, etc. It is the seat of the State penitentiary and has a public library, two hospitals, and several parks. Pop. (1910) 8,900; (1920) 12,066. FORTRESS, the development of mod- ern ordnance has rendered fortification as exhibited in the construction of the fortresses of the past practically obsolete and useless. It is probable that no for- tress in the world (with the exception, perhaps, of Gibraltar) would form a serious obstacle to a modern naval or land attack, if the assailants were pro- vided with the most approved modern heavy guns. In view of this fact, the construction of fortresses has been di- rected almost entirely to enabling them to cause a ricochet of shots directed against them rather than to oppose the direct impact. Hence modern foi'tresses are usually small, and present nowhere a direct angle to the line of fire, being generally constructed on the turtle-back or spherical plan. They usually contain but few guns, and those of the heavier calibers, rendering them offensive, rather than great strongholds of defense, as formerly. Of this latter class the strong- est fortress surviving in the United States is Fortress Monroe, on Hampton Roads in Virginia, erected for the defense of Norfolk navy yard and the Virginian coast at that point. It was planned and built by a French engineer, and was an important Federal strong- hold during the Civil War. Other im- portant historical fortresses are Mc- Henry, Moultrie, Pickens, Webster, St. Augustine, and Sumter. The greatest fortress in the world, from a strategical point of view, is the stronghold of Gibraltar, on the coast of Spain. It occupies a rocky peninsula jut- ting out into the sea, about one and a half miles in length and three-quarters of a mile in width. One central rock rises to a
