INDEX 



553 



Ventilation, best method, 178, 179 



by windows, 174, 175, 176 



difficulty of, 175 



experiment on, 179, 180 



laws of, 174 



method of, 174 



need of, 173 



of lungs, 180 

 Venus, 471 



Vibrations of sound waves, 412 

 Vinegar, 243 



test for, 243 

 Violin, 340 

 Virgo, 485 

 Vitamines, use of, 200, 201, 204 



where found, 200, 201, 204 

 Voice, human, 427 

 Volcanoes, 135 

 Volts, 386 

 Von Guericke, Otto, 56 



Washing machine, 497 

 Water, 257 



ammonia in, 277 



amount used, 265 



boiled in paper bag, 140 



composition of, 257 



condensing from vapor, 21 



electrolysis of, 257 



facts about, 257 



hard and soft, 278 



hydrants, 266 



lead in, 277 



loss by leaks, 275 



measurement of, 273 



meter, 273 



organic matter in, 277 



pressure, 261 



purification, 279 



salt in, 278 



Water, as a solvent, 268 



supply, 273 



systems, 265 



test, 277, 278 

 Watt, 386 



kilowatt, 386 



meter, 386 



watthour, 386 

 Weather chart, 78 



instruments, 78 



observations and predictions of, 77 



special observation on, 79, 80, 81 

 Weather lore, 80 

 Wells, artesian, 266 



water in, 284 

 Wheel and axle, 492 

 Window space, 372- 



shaded, 373 

 Winds, 62 



and barometer, 71, 72 



directions, 68 



pressure of, 66 



prevailing westerlies, 73 



table of, 65, 66 



trade, 73 



velocity, 65 



weather, 67 



world, 72 

 Windlass, 495 

 Wireless alphabet, 407 

 Wood cells in musical instruments, 421 

 Work, 491, 499 



of horse, 500 

 Wounds, care of, 322 



X-ray, 384 

 Xylophone, 442 



Year, length of, 469 

 Yeast, in making bread, 235 



