Irons, Electric, vii, 77 Iron Ships, floating of, iv, 104-5; magnetization of, 254 Iron Structures, magnetization of, iv, 253 Iroquois, Lake, iii, 149, 150 Iroquois Indians, and Mohawk Valley, xiv, 194; power of women among, xv, 295; union in nation, 363 Irrationality of Dispersion, ii, 101 Irrigation, development of methods, v, 239; in Egypt, 18-19, 178; electrical methods, vii, 231; in relation to critical periods, i, 250; sewage disposal by, viii, 327; snow sources, i, 118 Irritability (life), doctrine of, x, 86, 87, 88 Isallobars, i, 238 Ischia Earthquake, xiv, 339 Isinglass, iii, 334 Islands, classes, continental and oceanic, xiv, 271-9; formed on coasts, 251-2, 256, 258; historical importance, 281-2, xv, 137; new volcanic, xiv, 319; overpopulation of, 282; plants of oceanic, xiii, 348; tidal races produced by coastal, xiv, 294 Isobaric Elements, viii, 189 Isobars, i, 125, 375-6; classification, 238; spacing, 126; winds in relation to, 126 Isohyet, defined, i, 376 Isohyetal Charts, i, 206 Isomer, defined, x, 137 Isomerism, defined, viii, 378 Isomorphism, viii, 313 Isothermal, defined, iv, 382 Isothermal Changes, in gases, iv, 156, 159 Isothermal Layer (atmosphere), i, 19 Isotherms, i, 206, 207, 376; barriers to plants and animals, xiv, 364 Isotopic Elements, viii, 189 Israelites, "Cities of Refuge," xv, 369; life of, 199 Italian Honeysuckle, xiii, 142-3 Italian Language, descent from Latin, xv, 160, 162; musical terms from, 161 Italians, in Alpine group, xvi, 49 Italy, Adriatic coast, xiv, 252, 263; aeronautical weather service, i, 230, 304; Alps Mountains and, xiv, 244-5, xv, 138; "blood showers," i, 55; boric acid sources, viii, 90; brontides, i, 196; bubonic plague measures, x, 164; buffalo use in, xii, 329; earthquakes of, xiv, 332, 340-1; former connection with Tunis, 291; geographical changes in, 33; hail-shooting, i, 341, 342, 343; lakes, beauty of, xiv, 200; lakes, breezes of, i, 132; mercury production, iii, 370; meteorological observations, i, 68-9, 213; Napoleon's campaigns in, xiv, 244; paper-making, v, 290; rainfall, xiv, 358; Renaissance and science in, ii, 12-13; rice growing, xiii, 214; sea captains of, xiv, 310; volcanic power, v, 179-80; in World War, xiv, 244-5, 252-3, xv, 138; in World War, medical preparedness, x, 176 Itching, sensation of, ix, 92-3, xi, 109, 114 Ivory, elasticity of, iv, 36; sources of, xii, 302, 303 Izalco Volcano, xiv, 321, 325 Jackals, xii, 339-40; dogs and, 344; ears of, 346 Jack-in-the-Pulpit, in arum family, xiii, 188; flower, 52 (fig.); leaves, 183 (fig.); stems, 23 (fig.) Jacks, Hydraulic, v, 100, 101, 124, 260 Jackson, Dr. Charles T., x, 124, 125 Jackson, James, x, 116, xvi, 185