Temperature, of the isothermal stratum, 11, 12; and water vapor, 37, 38; difference between heat and, 49, 50; proper method of taking, 63; and frost, 85-97; and circulation of wind, 98-111; red lines on map indicate similarity of, 122, 123; record of, by balloons at high altitudes, 124; how amateurs may forecast, 151; with same solar heat differing, 162-166; causes of variations in, 163; of oceans, lakes, and rivers, 172, 173; extremely low, of ocean bottoms, 175, 176; of water changes with latitude, season and depth, 177; of earth at depth of 3490 feet, 179; daily range of, in free air, 185, 186; of interior of continents, 194; of coastal regions influenced by ocean in summer, 194; lowest recorded, at Weather Bureau, 195; highest, July, 195; average maximum and minimum, recorded by Weather Bureau, 195; extremes of, in Eurasian continent, 195-197; questionable effect of Gulf Stream on, 203; influence of valleys on, 203, 204; extremes of, on mountains, 204, 205; average monthly, in North America and the Old World, 207-210; at high altitudes, 210-212; effects of changes of, on man, 215; in its relation to health, strength, and efficiency, 215, 216; and mental activity, 216; proper percentage of humidity and, 217; the optimum of, for energy, 218, 219; regions of favorable, the summer, 250; author’s record of, in Bermuda, 257 Temperature inversion, 171 Temperatures, lag of earth’s, 168; annual range in air, 168, 169; highest and lowest: in North America, 275-278; in South America, 278; in Africa, 279; in Europe, 279; in Asia, 279, 280; in Australia, 280 Thermometer, Galileo’s discovery of principles of, 23; principles and discovery of, 62, 63; comparison of Fahrenheit and Centigrade scales of, 67, 68; data from, and meteorological science, 293 Thomson, Sir William. _See_ LORD KELVIN Thorium, nucleus of atom of, 32 Thunderstorms, effect of, on Lows, 132; cause, extent and movement of, 137; frequency of, 138; Highs and, 138; temperature and, 138; Lows and, 138; locale of, 138; and the formation of hail, 287 Tornadoes, 141-148; extent of, 141, 142; velocity and destructive force of, 142; locale of, 142; frequency of, 142; rate of movement and general direction of, 142; warnings of coming of, 142; seeking safety during, 142, 143; an American type of storm, 143; presence of water vapor necessary to cause, 144; use of weather map in forecasting, 144, 145; not increasing, 145; difficulty of forecasting, 146, 147; freaks of, 147, 148 Toronto, Canada, climate of, 210 Torricelli, and the barometer, 23, 292, 293 Trade winds, 101, 102 Transparency, 56 Tropical zone, cause of torrential rains in the, 100 Tropics, rain winds of the, 104, 105