416 



INDEX 



Tungsten light, 248 

 advantage of, 248 



Underclothes, 223 

 kinds, 222 

 mesh, 223 

 uses, 223 



Vaccination, 163 



Vacuum sweeper and cleaner, 353 



system of, 354 

 Ventilation, need of, 65 



principles involved, 66 



relation to health, 65 

 Vermiform appendix, 100 

 Villi, 100 

 Vitamines, 107 

 Vitreous humor, 258 

 Vocal cords, 375 

 Voice, 375 



control, 376 

 Volt, 364 

 Voltage, 363 

 Voltmeter, 364 



Wastes or poisons, 144, 145 

 body poisons, 166 

 removal from body, 145 

 removal from home, 146 



Water, 47 



composition of, 75, 180 



Water Continued 



cycle of, 76 



hard, 86, 87 



impure, 78 



lifted by air pressure, 80 



pure, 27, 74 



purification, 87 



rain, 76 



relation to body, 48 



relation to home, 79 



relation to soil, 300 



soft, 86, 87 

 Water seal, 151, 152 

 Weighing, 336 

 Weight, 333, 335 

 Wells, 77 



artesian, 77 



deadly, 79 



pollution of, 152 



safe, 79 

 Windpipe, 60 

 Wood, cross section of, 268 



relation of markings, 270 

 Wool, description of, 226 



relation to body, 227 

 Work, unit of, 339 



Yeasts, 117 



used in bread making, 117 



Zinc rod, 361 



