Smithsonian Report, 1913. — Devaux. 



Plate 1, 



Boat en route in Black Tray on Water Powdered with Talc. 



A large wake of camphorert water free from talc is very visible at the rear of the boat. The 

 operator contracts or expan<l.s the free surface by changing the position of the strip of 

 paper placed across the tray. 



