322 



INDEX. 



Stars, shooting, 96 _ 



oacur periodicruly, 9T 

 why not visible in the daytime, 



244 

 Starvation, process of, 239 



what is, 235 



Steam, bulk of, compared with water, 201 

 how much lighter than water, 



200 



engine, what is a, 202 

 high pressure, 202 

 how used for cookery, 202 

 invisible, 107 

 its elasticity, 201 

 lighter than air, 68 

 mechanical force of, 203 



illustrations of, 203 

 parts of a boiler where first formed, 



200 



power of, on what depends, 201 

 visible appearance how caused, 



200 



what is true, 200 

 Stems of grain -plants, why hollow tubes, 



37 



Stick immersed in water, why seems bro- 

 ken, 254 

 Still, construction of, 191 



Thunder, rolling of, cause of, 2S7 



storm", places dangerous in, 282, 



2S3 



safest in, 233 

 what is a, 2SO 

 varieties of, 2S7 

 what is, 2S6 

 why heard after the lightning 



is seen, 2S7 

 Tides, cause of, 59 



when high and low, 59, 60 

 Toes, advantage of turning out the, io 



walking, 17 

 Tornadoes, 82 



phenomena generally attend- 

 ing, 82 



Transparent bodies, what are, 260 

 Tree, centre of gravity in, 19 



how discharges a lightning cloud, 



2S2 



Trees and flowers, how purify the air, 210 

 whv covered with straw in winter, 



184 



Tropics, rainy and dry seasons of, 109 

 Troy weight, origin of, 20 

 Trumpet, ear, construction of, 127 



speaking, construction of, 127 

 Twilight, cause of~ 259 



Telegraph, influence how transmitted by, 

 to convey intelligence, 301 

 magnetic, Morse's, principle 



of, 300, 301 

 wire, why supported on glass, 



301 ' 

 Telegraphic current, what is meant by 



301 

 Telescopss, construction and use of, 252, 



253 

 why enable us to see 



objects, 253 

 Temperature, effect of the sea on the, 107 



soil on, 107 



mean daily, what is, 106 



varies with altitude, 105 



latitude, 105 



variation, examples of, 105 

 why all places have 



same, 107 

 Temples, how cooled by ether, cologne, 



water, &c., 197 

 Tenon, what is a, 43 

 Terra-cotta, what is, 39 

 Thaw, mo-e chilly than a frost, 183 

 Thermometer, centigrade, 191 



Fahrenheit's, 190 



Eeaumer's, 191 



indicates difference of heat 



only, 192 

 Thermometers and pyrometers, difference 



of, 188 



construction of, 189 

 different, 190 

 how graduated, 189 

 Thunder, cause of, 286 



Vacuum, illustration of, 213 



what is a, 71 

 Valves, pump, 93, 99 

 Vapor from damp linen, what is it, 197 

 in a room, origin of, 88 

 of the air, how condensed into rain 



91 



Vaporization, meaning of, 194 

 Vegetables, why swell in boiling water, 



distant Vegetation, why luxurious on the margin 



of a river, 66 

 Ventilation, in what situations is it perfect, 



205 



what is, 204 



Vibration, what is a, 116 

 Vibrations, sonorous, how illustrated, 116 

 Vinegar, what is, 305 

 not the Vitriol, oil of, 304 



Voice, organs of, 122 



tones of, how altered, 122 

 Volatile substances, 195 

 Volcanoes, probable cause of, 136 



Wall, a, when stands securely, 17 

 Walls, partition, construction of, to int 



cept sound, 119 

 Warming and ventilation, 204 

 Water, a bad conductor of heat, 146 



at what elevation above the earth 



remains frozen, 106 

 air in, 

 boiled, why flat and insipid, 73 



