SMITHSONIAN MISCELLANEOUS COLLECTIONS 

 VOLUME 140, NUMBER 3 



DOCTOR LANGLEY'S PARADOX: TWO 



LETTERS SUGGESTING THE 



DEVELOPMENT OF ROCKETS 



(With Three Plates) 



By 

 RUSSELL J. PARKINSON 



Museum Aide, National Air Museum, Smithsonian Institution; and 

 Instructor of History, Duke University 



(Publication 4424) 



CITY OF WASHINGTON 



PUBLISHED BY THE SMITHSONIAN INSTITUTION 



AUGUST 31, 1960 



