INDEX 



603 



radiant, 121; factors of heat 

 quantity, 129; sensible, 129, 167; 

 of vaporization, 129; of conden- 

 sation, 167; sun's, how it varies, 

 282; effect of sun's upon atmos- 

 phere, 205; produced by fric- 

 tion, 549; work equivalent of, 

 551; value of solid fuels, 109; 

 value of gaseous fuels, 105; 

 value of foods, 353; and tem- 

 perature, 129; of fusion of ice, 

 161. 



Heating, by stove, 120, 122; by 

 furnace, 123; by hot water, 127; 

 by steam, 131; hot water and 

 steam systems contrasted, 132; 

 vacuum system; 140: effect of 

 the sun, 281-286; of one-room 

 school, 331; of several-room 

 school, 333; plenum system of, 

 333. 



Henry's law, 480. 



Highs, described, 264; paths of, 

 268; unusual paths of, 272; of 

 the entire earth, July, 278; of 

 the entire earth, January, 279. 



Horse, work by, 552 ; cost of feed- 

 ing, 554; efficiency as a motor, 

 554. 



Horsepower, 541. 



Horsepower-day, cost by steam 

 engine, 552; cost by horse motor, 

 553; cost by human labor, 555. 



Horsepower-hour, equivalent in 

 calories, 552. 



Hot blast, on stoves and furnaces, 

 97. 



Hot water for use in country 

 homes, 479; in city residences, 

 490; in the 18th Century, 500; 

 in modern residence, 479, 490, 

 501. 



Hot water heating, 127; essential 

 features, 128; advantages of , 128, 

 contrasted with steam, 132; and 

 ventilation, 330 



Human body, temperature of, 317; 

 temperature of and metabolism, 

 318; composition of, 344; its 

 needs, 344. 



Humidity, absolute, 158; relative, 

 158; seasonal changes in relative, 

 293; maps of, relative, 294, 295, 

 296; relation to ventilation, 316; 



importance of, 321; how regu- 

 lated, 325; of schoolrooms, 327; 

 relative, Table, 218; absolute, 

 Table, 220. 



Humphrey Potter's invention, 568. 



Hydrocarbons, 87. 



Hydrogen, preparation of, 85; 

 properties of, 85; explosive mix- 

 ture of, 87. 



Hydrometer, Baume"s, 27; use in 

 testing oils, 28. 



Hydrophobia, 446. 



Hydrophytes, 466. 



Hygrometer, 216; hair, 219; use in 

 schoolroom, 325. 



Hyphae, 385. 



Hypocaust, Roman, 112. 



Ice, manufacture of, 163 ; plant, or 

 factory, 163; melting point of, 

 15; heat of fusion of, 161; cream, 

 freezing of, 170. 



Ignition, 578. 



Illuminating gas, 43; measurement 

 of, 43; cost of, 68; composition 

 of, 105; used as fuel, 101. 



Illuminating oil, 6, 25, 26; inspec- 

 tion of, 28. 



Immunity, 427; natural, 427; ac- 

 quired^ 427. 



Impulse water wheel, 558. 



Incandescent lamp, 51; gas mantle, 

 62, 68. 



Indirect radiation, 330. 



Infantile paralysis, 448. 



Infiltration galleries, 460. 



Influenza, 440. 



Jenner, Edward, 429. 



Kerosene, 6, 25, 26; vapor of, 8; 



danger of cheap, 31. 

 Kerosene lamp, 5, 33; parts of, 6; 



chimney and burner, use of, 6. 

 Kilogram, 536, 539. 

 Kindling temperature, 85. 

 Koch, Robert, 398. 



Lactose, 349. 



Lakes and rivers, origin of, 457. 



Lamp, primitive, 2; Greek and 



Roman, 2; kerosene, 5; gasoline, 



34, 36. 



