INDEX. 



323 



Water, composition of, 54 I Wheels, carriage, why sometimes take 



declivity sufficient to give fanning lire, 189 



motion to, 50 fore, of carriages, why smaller 



of, why rolls upon hot iron, than the hind, 44 



of carriages, utility of greasing, 



water, different kinds, 34 

 Whitewash, what is, 38 

 Wick of a candle, why not consumed, 



233 

 Windpipe, what is the, 122 



194 



expands when freezing, 181 

 force of expansion in freezing, 179 

 hard, what is, 54 



difficult to wash in, 56 

 bow extinguishes a fire, 229 

 hoAV heated, 153 



hot, why hreaks glass, or earthen Windows, why blaze p.t sunset, 249 



vessels, 185 

 in freezing, cracks earthen ves- 

 sels, 180 



images in, appear inverted, 246 

 power, 33, 34 

 pressure of. 53 



how exerted, 53 

 of mineral matter con- 



tained in, 55 

 running, Avhy slow to freeze, 182 

 scalds at what temperature, 176 

 surface of, always level, 49 

 swells in boiling, 156 

 temperature ol'boiling, 135 

 what is the purest natural, 55 

 when affects lead pipes, 310 

 why a fluid, 54 



why dissolves sugar and salt, 57 

 why freezes first at the surface, 



182 



why rises in a pump, 101 

 why sparkles, 56 

 why will not dissolve iron, 193 



Waters, relative purity of, 55 



Waterspout, what is a, 83 



Waves, cause of, 60 

 spray of, 61 

 velocity of storm, 61 



Well, ordinary, why water collects, 57 



Wells, artesian, 52 



why often covered with mist, 



87 



Wind, cause of, 75 

 Winds, force of, how measured, 78 



high, difficult to walk against, 9 



always blow, 76 



effects of mountains, on the couira 

 of, 76 



land, generally dry, 76 



north, why cold, 79 



south, why Avarm, 79 



regular, 77 



on" the direction of, 78 



trade, 77 



velocity of, 77 

 Wine, why sours on exposure to air, 305 

 Wood, constituents of, 224 



green, unprofitable to burn, 227 



hard and soft, 227 



how preserved from decay, 811 



"; profitable for f;i 

 kinds of, which impart the least 



kinds most profitable for fuel, 227 



heat in burning, 227 

 weight of a cord of, 227 

 why does not melt, 194 

 why generally cut in the winter, 



why snaps when burning, 7 

 Wooden handles, why applied to cooking 

 vessels, 145 



Winter, dark dresses most suitable for, Woollen kettle-holders, utility of, 145 



172 



Teast, what is, 305 



Yellow, the color most visible, 272 



Weather, action or. building materials, 



48 

 Weather, animals foretell changes in, 113 



moon's influence on, ill 

 Weight, how varies, 19, 20 



proportional to what, 19 



what is, 19 



where a body has the greatest, 



and least, 20 

 Weights and measures, English system of, 



21 Zenith, what is the, 269 



Weights and measures. French system of, Zero point of thermometer, how dele* 



21 i mined, 190 



Wheel, centre of gravity of, 18 ^Zodiacal light, 97 



dished, or arched, stronger than a 

 flat, 44 i 



Woollens, utility of as protectors against 

 cold, 147 



