SMITHSONIAN CONTRIBUTIONS TO KNOWLEDGE, 



CONTRIBUTIONS 



TO 



THE PHYSICAL GEOGRAPHY OF THE UNITED STATES 



PART I. 

 OF THE PHYSICAL GEOGRAPHY OF THE MISSISSIPPI VALLEY, 



WITH SUGGESTIONS FOKTHE IMPKOVEMENT OF THE 



NAVIGATION OF THE OHIO AND OTHER RIVERS: 

 By CHARLES ELLET, Jr., CIVIL ENGINEER 



[ Received, September 17, 1849. ] 



ART. 4. 



