Page:The American Cyclopædia (1879) Volume IX.djvu/390

 376 IRON IRON-CLAD SHIPS KINDS. Ultimata breaking strain in 11*. per >q. inch. Elonga- tion for cent. Strain applied in lb. per ]. inch. Difference in maximum and minimum. No. of applications before fracture. Orlg. rt. Fract'd are*. Maximum. Minimum.

21.400 25,080

37.450

Wroapht iron, Phoenix company, I Ih37 f 47,080 109,675 66,126 135,997 H-8-j 12-1- 51,360 88,520 47,030 47,080 85,600 49.220 85,600 17,050 10,700 51, SCO 88.520 25,680 21,400 65.600 49,220 48.150 17.050 10,700 800 480,852 2,373,424 4,000,000 not broken. 18,741 13.200.000 not broken. 12,000.000 not broken. 8,140 7,600,000 not broken. Piece of cast-Jron cylinder, Stettin. The effect of vibration on fibrous iron, it has been generally supposed, is to make it crystal- line. Experimental evidence is however lack- ing on this point. Iron subjected to vibratory shocks may become weak and break from " fa- tigue," or by reason of poor material or bad working ; but there are no facts to prove that weakening is the result of a passage from the fibrous to the crystalline condition. Prof. Robert H. Thurston has investigated the effect of unintermitted static stress on wrought iron and steel strained beyond the limit of elastici- ty, and has found that they do not lose their power of resistance or yield in the slightest de- gree. He has further determined that iron and steel, if strained beyond the limit of elas- ticity, and left under the action of the distort- ing force which has been found just capable of equilibrating their power of resistance, gain resisting power to a degree which has a limit in amount approximating closely, if not coin- ciding with, the ultimate resistance of the ma- terial, and which had a limit as to time in ex- periments hitherto made of three or four days. Releasing the piece entirely and again submit- ting it to the same force immediately does not produce this strengthening effect. The pro- duction of iron and steel in the United States in 1872 was as follows, in tons of 2,000 Ibs. : Iron and steel rails 941,992 Other rolled and hammered iron 1,000,000 Forges and bloomaries 58,000 Cast Bteel 82,000 Bessemer steel 110,500 Martin steel 8,000 Tig iron 2,830,070 The following is the production of England. Prussia, and Sweden for 1871, and France for 1872: COUNTRIES. Fig iron. Wrought Iron. Steel. 6,627,179 1,827.934 1,299,890 292,850 5,56< 897,273 971,889 188,989 >,175 211,867 152.409 84,388 Prussia IRON. I. A S. E. county of Missouri, drain- ed by affluents of the St. Francois and Big Black rivers; area, about 500 sq. m. ; pop. in 1870, 6,278, of whom 352 were colored. Iron moun- tain arid Pilot Knob are on the N. E. border. The surface is hilly and mountainous. There are large forests of oak, hickory, pine, and ce- dar. Iron ore is abundant, and other metals are found. The St. Louis and Iron Mountain railroad crosses the county. The chief produc- tions in 1870 were 12,221 bushels of wheat, 90,385 of Indian corn, and 28,141 of oats. There were 690 horses, 919 milch cows, 1,703 other cattle, 3,178 sheep, and 4,714 swine; 5 manufactories of carriages, 1 of charcoal, 1 of pig iron, and 5 saw mills. Capital, Ironton. II. A S. county of Utah, extending from Col- orado on the E. to Nevada on the W. ; area, 9,200 sq. m. ; pop. in 1870, 2,277. It is inter- sected in the E. by the Colorado river, and crossed in the W. by the Wasatch mountains. Iron ore is found in this range, and at its base is some land suitable for agriculture, but much of the county is unavailable. The chief pro- ductions in 1870 were 8,917 bushels of wheat, 2,857 of Indian corn, 21,276 of potatoes, 17,968 Ibs. of wool, 21,355 of butter, and 736 tons of hay. There were 732 horses, 2,114cattle, 4,502 sheep, and 3 saw mills. Capital, Parowan. IRON-CLAD SHIPS, or Armored Ships, vessels covered or plated with iron for the purpose of rendering them impenetrable to the fire of ar- tillery. The idea of strengthening the sides of ships so as to enable them to resist attack is nearly as old as the art of navigation itself. From the time of the Norman freebooters, who protected themselves by ranging their bucklers along the sides of their vessels, down to the battle between the Kearsarge and the Alabama in 1864, in which the sides of the former were protected by hanging chains over the bulwarks, and from the time of the Ro- mans, who built their triremes with castellated prows, to the English, who have covered their frigates with plates of solid iron, all nations have sought by means more or less perfect to make their ships impenetrable, and to render them invincible in battle. The first attempts at making iron-clad vessels were made by the Normans in the 12th century, who put an ar- mature or belt of iron around their vessels, just above the water line ; this belt terminated in front by a spur. In some instances this ar- mature was converted into a curtain of iron or brass reaching above the bulwarks for the pro- tection of the combatants. The crusaders of the 12th and 13th centuries protected their ships in a similar manner. Pedro of Aragon in 1354 ordered the sides of his ships to be covered with leather or raw hide to protect them against incendiary compounds. Andrea Doria, who commanded in the expedition