Smithsonian Report, 1951.— Laufer 



Plate l 



Ultrasonic waves, coming' from the liny whistle on the end of the J-shaped tube, are re- 

 flected onto the table bv the concave metal disk. The ridges, formed in talcum powder, 

 show the standing waves formed by reflections from the table top and beaker. Courtesy 

 General Electric Co. 



