INDEX 



433 



Voice, 301 



Volt, 251, 252, 423 



Washing soda, 20 



Water, 6, 19, 20, 82, 92, 121, 134, 310; 



power, 199; pressure, 230; supply, 



225 



Water and disease, 226 

 Water and forests, 233 

 Waterfall, value of, 203 

 Watt, unit of power, 198 

 Weather Bureau, 160; maps, 160 

 Wedge, 1 88 

 Wells, 224 



Wheat, 361; rust, 373 

 Wheel-and-axle, 194 

 Wind, 99 

 Windlass, 194 

 Windmills, 204 

 Wireless apparatus, 265 

 Wood alcohol, 89 

 Work, denned, 178 

 Worms, 384 



Yeast, 24, 27, 28, 371 

 Yellow fever, 400 



Zygospore, 369 



