Energy, conservation of, iv, 40-1 (see Conservation of Energy); defined, 13-14, 37-9; equation of, 78; force contrasted with, 41; forms and transformations, 81-8; future sources of, v, 171-81; heat equivalent (see Mechanical Equivalent of Heat); kinetic and potential, iv, 79, 81-5, vii, 368; matter and, iv, 13-14; of plants and animals, viii, 334, 335, 336, 347, 349, 350 (see also Human Energy); physics as science of, iv, 12, 13-14, 50; power differentiated from, 80; radiant (see Radiant Energy); sources in nature, viii, 267-8, ix, 25-6, xiv, 31-2; sun as source of, v, 177, viii, 267, 334, 350, ix, 25-6, xiv, 32; transference and transformation of, iv, 37-41, 81-88, vi, 128-9; units of, iv, 79-80, ix, 295; unit equivalents table, vii, 382; universality of, iv, 13-14; work and, 37-40, 78-88; (see also Atomic E., Chemical E., Electrical E., Human E., Molecular E., Power) Engines, air and water cooled, v, 160-1; Clausius's principle, xvi, 135; heat, efficiency of, iv, 192; reciprocating and rotary, v, 148; two-cycle and four-cycle, 157-9; (see also Gas Engines, Gasoline Engines, Internal Combustion Engines, Steam Engines, etc.) Engines of Destruction, v, 359-75 England, Alpine Invasion, xvi, 49; beet cultivation in, xiii, 216; "Blackthorn winter," i, 363; chalk deposits, iii, 266; climate of, xiv, 345; coal supply, v, 172; coast destruction, iii, 56, xiv, 47, 301; coffee consumption, xiii, 232; early criminal justice in, xv, 372; first recorded eclipse, ii, 210; former connections with Europe, xiv, 271-3, xv, 76; grass snake of, xii, 217-18; insular position and results, xiv, 279-81, xv, 137; iron industry, v, 316; jute manufacture, xii, 243; lakes of, xiv, 200; landscape gardening, xiii, 267, 268; maritime supremacy, xiv, 262, 280-1, 307-8, 310; oak-hazel copses, xiii, 369-70; primitive inhabitants, xv, 83, 92-3; rainfall and verdure, xiv, 352; recent restrictions on power vehicles, v, 212-13; smallpox inoculation in, x, 207; sugar in, xiii, 215; surgery made a profession, x, 105; tea in, xiii, 228-9; tobacco introduction, 256; trees in, xiv, 375 English Alphabet, xv, 176 English Channel, first aeroplane flight, i, 43; historical importance, xiv, 279-80, xv, 137; impassable to quadrupeds, xiv, 273; tidal power system, v, 175-6; tides of, xiv, 294 English Language, changes in, xv, 156-7; double meanings of words, 158-9; foreign words in, 161; imitative words in, 153-4; origin of various words, 157, 161; relationships, 160, 162; spelling and pronunciation, 176-8 English People, characteristics, xiii, 172; insularity of, xiv, 280 English Sparrow, increase in U. S., xv, 21 Entada Scandens, xiii, 347-8 Enterokinase, x, 326