LANGLEY— LEFFMANK. 167 



replaced by an 80-horsepower Curtiss motor, and direct-connected 

 tractor propellers. In the absence of Mr. Curtiss, a pupil of his 

 school, Mr. Doherty, took the wheel. Beginning September 17, a 

 number of flights were made, which demonstrated that the general 

 principles of Langley's construction were perfectly sound, and to him 

 must be given the credit of being the pioneer in practical aviation, 

 and of having, by his devotion and persistence, helped to bring into 

 a field of scientific inquiry what had been previously almost entirely 

 in the possession of visionaries or charlatans. In this connection 

 we must not overlook the services of Manly, to whom is due largely 

 the construction of a satisfactory gasoline engine, then first used in 

 an aeroplane, and who twice risked his life in trials of the large 

 machine. 



The following paragraphs are copied verbatim from the article 

 indicated in the footnote on page 160 : 



Dr. Langley's aerotechnic work may be briefly summarized ns follows: 



1. His aerodynamic experiments, some published and some as yet unpublished, 

 were complete enough to form a basis for practical pioneer aviation. 



2. He built and launched, in 1S96, the first steam model aeroplane capable 

 of prolonged free flight and possessing good inherent stability. 



3. He built the first internal-combustion motor suitable for a practical man- 

 carrying aeroplane. 



4. He developed and successfully launched the first gasoline model aeroplane 

 capable of sustained free flight. 



5. He developed and built the first man-carrying aeroplane capable of sus- 

 tained free flight. 



