Humboldt, Baron von, on civilization and climate, 214 Humidifiers, 72 Humidity, percentage expression of relative, 38, 39; absolute, 39, 68-74; tables of relative, 69-71; importance of proper, in living quarters, 72; diseases due to lack of, 73; and conservation of fuel, 73, 74; excessive, harmful to man, 216, 217; proper percentage of, 217 Huntington, Ellsworth, comparison of temperatures by, 196, 197, 215; on human energy, 217, 218; on examination of big trees in California, 236, 237 Hurricane, West Indian, 133, 134; the Galveston, 134; nature and development of, 134, 135; exposure of Atlantic coast to effects of, 135, 136 Hurricanes, general extent of, 141 Hydrogen, in earth’s atmosphere, 5, 6; nucleus of atom of, 31; and oxygen combined to form water, 32; density of, 39; combustible properties of, 39; sources of supply of, 39, 40 Hygrometer, for measuring water vapor, 39 Ice, and bacteria, 43; formation of, 43; specific heat of, 56; latent heat of melting, 57; melting of, under pressure, 60 Ice ages, 239 Ice Cap, possible return of Great, 240 Iceland, sub-permanent Highs and Lows in region of, 159 Inclosed seas, temperature of waters of, 176-178; latitude, season and depth change temperature of, 177, 178 Indian Ocean, and monsoon winds, 106, 107; temperature of waters of, 176 Industry, benefits of Weather Bureau service to, 301, 302 Instrument shelter, 66-68 Instruments, in meteorological stations, 63; for voluntary observer, 66-79 Invisible light, 52, 53 Iron, nucleus of atom of, 32 Isobars, on weather map, 115 Isothermal lines, ocean currents and changes in, 201, 202 Isothermal stratum, height of, 11; temperature of, 11, 12, 211 Jacksonville, Fla., meteorological statistics for, 263 Japan, Christmas Day in, 273 Jefferson, Thomas, on the changing climate, 227; records of readings of thermometer by, 232; barometrical records of, 233; loss of his barometer, 233; weather observations by, 296 Jupiter, atmosphere of, 3; and heat from sun, 3 Justice, weather records serve ends of, 79-83 Kansas City, Mo., climate of, 210 Kelvin, Lord, on the size of molecule of water, 30 Kites, in meteorological research, 19; use of, by Weather Bureau, 22; rectangular form of, 22; observations from, 64; construction and flying of, 64-66 Krakatoa, effects of eruption of, 43, 44 Krypton, 33 Lake Owens, Cal., waters of, have receded, 235 Lake Superior, temperature of waters of, 178 Lakes, influence of, on climate, 199, 200 Lapham, Dr. I. A., 298; urges establishment of weather service, 305 Latent heat, 56-58 Latitude, its relation to health, strength, and efficiency of man, 218 Lead, nucleus of atom of, 32