Deliberation, after contact and distance sensations, ix, 95, 121, 140; nervous delays in, 140, 141, xi, 20, 21; value of, 139 Delirium, Brown on, x, 89; hot baths in, 311 Delta Connections (electric), vi, 210-11, 318, 325 Delphi, Oracle of, xv, 351-2 Deltas, iii, 32, xiv, 53; alluvial soil of, 70; coasts formed by, 53, 263; in lakes, 202, 210-11; lakes formed by, 203; rivers joined by, 185 Delusions, x, 358-9 Demagnetization, vi, 37-8, 117, vii, 366; by heat, iv, 253; test, vi, 43 Dementia Precox, x, 237 Democritus, on knowledge, xvi, 87; on matter, 83; on origin of earth, ii, 366-7 Demosthenes, timed speeches, v, 62 Denatured Alcohol, viii, 250 Dendrites, xi, 18, 19; receptors for pain, 117 Denmark, antiquity of man in, xv, 86-7; föhrden of, xiv, 259; forests and peat bogs, xv, 86-7 Density, absolute, iv, 110-11; methods of determining, 111-12; of liquids, how measured, 113, vi, 147; of various substances, iv, 113; specific, 111; standard of, 149 Densmore, James, v, 312 Dental Arches, xv, 98 (fig.) Dentistry, hypnosis in, xi, 316; protection against pain, 121 Denudation (see Erosion) Denver, boiling temperature in, iv, 170 Deodorants, inhibition in, xi, 81 Department Stores, Christmas lighting, vii, 342; pneumatic tubes in, iv, 130; rain and business, i, 265 Deperditometer, i, 319, 371 Depolarization, of electric cells, vi, 137, 139, vii, 366 Depression, of land and sea areas, (see Subsidence) Depressions, (geological) in land, xiv, 204-5; in ocean floor, 286 Depressions (meteorological), i, 135, 371 (see Lows) Depth, perception of, ix, 119-20, xi, 173-85 Derborence, lakes of, xiv, 202 Derived Proteins, viii, 352-3 Derived Units, iv, 46, xvi, 131 Dermographism, xi, 317 Dermoid Cysts, x, 120 Desault, Pierre, x, 91-2 Descartes, influence of, x, 67; mathematical and scientific work, ii, 15, xvi, 113-14, 118-19; theory of vortices, ii, 60 Descriptive Astronomy, development of, ii, 15-16, 113-14, 119, 139 Deserts, density of air over, i, 171; dust whirls, 60; evaporation in, 323; in trade wind belts, xiv, 355-6, 380; irrigation by sun-power, v, 178; lizards of, xii, 206; mirages, i, 172-3, 174, iv, 328-9; rainfall, i, 112; rainfall and plants, xiii, 377-81; rock weathering in, iii, 23, 71-3, xiv, 42, 77, 79; salt deposits, viii, 197; "stretching" of, xi, 173; water-storing plants, xiii, 28, 30, 41-2, 104, 106-7, 336 (illus.); wind action in, iii, 71-5 (see also Arid Regions) Desert Sounds, i, 196, 371 Desert Topography, xiv, 41-2 Design, elements of (prehistoric), xv, 299 Designs, enlargement of by lanterns, iv, 342 Desires, suppression of, xi, 140-2 (see also Suppressions) Despondency, indigestion and, xi, 370 (see also Dejection)