Clay, composition and properties, viii, 90, 282; composition, origin and uses, iii, 25, 372-3; elasticity of, iv, 36; imperviousness to water, xiv, 137; in soils, iii, 27-8; red, on sea bottom, 54; residue of primary rock, viii, 195; rock formed from, iii, 13 (see Shale) Clay Worm, xii, 54 Cleanliness, bathing for, ix, 313; health and, x, 311; in war against tuberculosis, 290; ventilation factor, ix, 270 Cleansing, action of soap in, viii, 141-2; chemicals used in, 135, 141, 146, 147, 208-9 Cleavage, of crystals, iii, 318, viii, 202; of various minerals, iii, 321-41 Cleistogamous Flowers, xiii, 120 Clematis, as index plant, i, 255; family of, xiii, 196 "Clermont," steamboat, v, 192, 377 Cleveland, Ohio, water supply system, v, 260-1; water supplies and typhoid rate, viii, 322 Cliffs, formed by faulting, iii, 87-8, xiv, 38; in inclined strata, xiv, 84-5, 88; loess, iii, 74; of jointed rocks, xiv, 133; sea, 251; undercut by wind, iii, 73 Climate, Climates, i, 197-211; altitude effects, xiv, 220, 223; carbon dioxide effects, viii, 49; changes of, i, 199-202, xiv, 29-30, 360-2, xv, 72, 73, 74; changes affecting drainage systems, xiv, 188; changes, artificial, i, 345; changes, extinction of races by, xv, 99; changes in relation to plant distribution, xiii, 320, 321; civilization, and, xiv, 344, 357-62, xv, 123-7, 383; classification, i, 208; data and statistics, 202-8, 214; definitions, 199; determining elements of, xiv, 344-56; earth's internal heat and, 13; effects, historical and biological, xvi, 141-2; forest and prairie types, xiii, 348-9; forest effects on, xiv, 379; Gulf Stream effects, viii, 37; hot, unhealthfulness of, x, 251; human effects of, i, 316, 323-4, 327, 331; human efficiency and, xiv, 357; of past ages, iii, 172-4, 178, 184-5, 202, 203, 204, 220, 241, 246-8, xiii, 307-8, xv, 72, 73, 74, 76; of plateaus, xiv, 222-4; plant societies determined by, xiii, 381-2; rugged, effects on circulation, x, 238-9; therapeutic value of, 383; topographical effects of, xiv, 41-2, 51-2, 124; vegetation determined by, 363-79, 380-1; zones of, (see Zones) Climatic Charts, i, 206-8, 212-13 Climatography, i, 208, 369 Climatology, in therapeutics, x, 383; present state, i, 211, 369 Climbing Plants, xiii, 27, 65; in tropical forests, xiv, 368 Climographs, i, 324, 369 Clinton Iron Deposits, iii, 358 Clione, xii, 19 Clippers, old Atlantic, v, 188 Clocks, balance wheels of, v, 68; Chaldean, xvi, 58; electric regulation, v, 74; first conceived in cathedral, 109; historical development, 58-65; Jerome's standardized, 50-1; pendulum escapement, 73-4 Closed Circuits, defined, vii, 364 Cloth, making of, v, 268-83 (see also Weaving)