Show Dig mg NOise oise Finds Flaws The wide use in industry of sound waves too shrill to be heard by the human ear was recently described These high frequency sound waves are becoming increasingly im im- important important as a tool for material test test- testing testing ing and Flaws hidden deep inside structures as large as the driving wheels of a locomotive are arc readily located by scanning with ultrasonic waves to spot the offend offend- offending offending ing fault This versatile technique can also be used to measure the thickness of coatings as thin as the polish on miladys milady's nails |