Hemorrhages, blood transfusion in, x, 338; low blood pressure in, 336; prevention of, in surgery, 14, 148; stopping of, ix, 179-81 Hemostat, x, 148 Hemp cellulose composition, viii, 254; sources, xiii, 238 Hemp Plant, xiii, 238-9 Henna Dye, of Amatus, x, 58 Henry, induction unit, iv, 285 Henry, Prof. Joseph, i, 189, vi, 24, xvi, 191; induction unit named for, iv, 285 Henry I, (England), arm's length of, iv, 45 Henry the Navigator, xiv, 309 Henry Mountains, iii, 139, xiv, 109, 227 Hens, language methods of, xv, 141 Heraclitus, on change, xvi, 79 Herbivora, xii, 300-31; intestine length in, ix, 246 Herbs, antiquity, xiii, 319, 310; in American summer forests, 368, 369; as class of plants, 175; fossil and existing species, 324; garden, 289; hairy covering, 104-5; none among gymnosperms, 175; planting table of annuals and perennials, 290-7; stems, 23; in temperate forests, 366 Hercules (constellation), star clusters in, ii, 336, 340; stars moving from, 305 Herd-Instinct, x, 9 Hereafter, primitive conceptions of, xv, 332-6, 339, 340, 345 Heredity, x, 227-8; diseases and, ix, 103, 181, 304, x, 234-5, 292, 303; importance in human evolution, xvi, 47; importance of knowledge of, x, 236; laws and facts of, ix, 325-44, x, 228-34, xiii, 326-7, 331-4, xv, 22-3, 24, 27, xvi, 153-8; social, xv, 30-1 Hering, Prof. D. W., author PHYSICS, Vol. iv Hering's Illusion, xi, 189 Hermit Crab, xii, 85 Hernia, operations for, x, 14, 41, 57 Hero, Greek scientist, inventions, xvi, 91, 92, 93; mathematical work, 95; steam turbine, v, 142-4, 148, xvi, 92, 93 Herodotus, Barton on, x, 20; on fossil shells, iii, 14; on Egyptian geometry, xvi, 68; on Nile River, xiv, 71 Heroism, in crowds, xi, 326-7, 330 Herons, xii, 254-5 Herophilus, x, 23-4 Herring, xii, 154, 156; limacina and, 19 Herschel, Caroline, ii, 104 Herschel, Sir William, astronomical work, ii, 15-16, xvi, 124-5; discovery of Uranus, ii, 267; father of descriptive astronomy, 139; ideas of nebulæ, 368-9, 380; knighting of, 254; on habitability of sun, 252; on proper motion of stars, 305; picture of solar system, 162-3; reflectors of, 103, 104; studies of Galaxy, 352; studies of Mars, 227; studies of nebulæ, 358 Herschel, Sir John, dismantling of telescope by, ii, 104; on spectrum lines, 112; on Galaxy, 352; studies of nebulæ, 358-9; studies of star clusters, 336-7 Hertz, Heinrich, vi, 25, vii, 258, xvi, 191 Hesperornis, xii, 242 Hesperus, ancient name of Venus, ii, 191 Hessian Fly, i, 256 Hetchy-Hetchy Canyon, iii, 225 Heterodyne Receivers, vii, 278-9 Heterogeneous Rivers, xiv, 154-5 Heteromecic Numbers, xvi, 80 Hevelius, astronomer, ii, 57, 85; telescopes of, 48, 99; halo of, i, 374 Hewson, William, x, 88, xvi, 179